Merge tag 'sound-fix-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai...

[mirror_ubuntu-jammy-kernel.git] / include / linux / lsm_hooks.h

/*
 * Linux Security Module interfaces
 *
 * Copyright (C) 2001 WireX Communications, Inc <chris@wirex.com>
 * Copyright (C) 2001 Greg Kroah-Hartman <greg@kroah.com>
 * Copyright (C) 2001 Networks Associates Technology, Inc <ssmalley@nai.com>
 * Copyright (C) 2001 James Morris <jmorris@intercode.com.au>
 * Copyright (C) 2001 Silicon Graphics, Inc. (Trust Technology Group)
 * Copyright (C) 2015 Intel Corporation.
 * Copyright (C) 2015 Casey Schaufler <casey@schaufler-ca.com>
 * Copyright (C) 2016 Mellanox Techonologies
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 *      Due to this file being licensed under the GPL there is controversy over
 *      whether this permits you to write a module that #includes this file
 *      without placing your module under the GPL.  Please consult a lawyer for
 *      advice before doing this.
 *
 */

#ifndef __LINUX_LSM_HOOKS_H
#define __LINUX_LSM_HOOKS_H

#include <linux/security.h>
#include <linux/init.h>
#include <linux/rculist.h>

/**
 * union security_list_options - Linux Security Module hook function list
 *
 * Security hooks for program execution operations.
 *
 * @bprm_creds_for_exec:
 *      If the setup in prepare_exec_creds did not setup @bprm->cred->security
 *      properly for executing @bprm->file, update the LSM's portion of
 *      @bprm->cred->security to be what commit_creds needs to install for the
 *      new program.  This hook may also optionally check permissions
 *      (e.g. for transitions between security domains).
 *      The hook must set @bprm->secureexec to 1 if AT_SECURE should be set to
 *      request libc enable secure mode.
 *      @bprm contains the linux_binprm structure.
 *      Return 0 if the hook is successful and permission is granted.
 * @bprm_creds_from_file:
 *      If @file is setpcap, suid, sgid or otherwise marked to change
 *      privilege upon exec, update @bprm->cred to reflect that change.
 *      This is called after finding the binary that will be executed.
 *      without an interpreter.  This ensures that the credentials will not
 *      be derived from a script that the binary will need to reopen, which
 *      when reopend may end up being a completely different file.  This
 *      hook may also optionally check permissions (e.g. for transitions
 *      between security domains).
 *      The hook must set @bprm->secureexec to 1 if AT_SECURE should be set to
 *      request libc enable secure mode.
 *      The hook must add to @bprm->per_clear any personality flags that
 *      should be cleared from current->personality.
 *      @bprm contains the linux_binprm structure.
 *      Return 0 if the hook is successful and permission is granted.
 * @bprm_check_security:
 *      This hook mediates the point when a search for a binary handler will
 *      begin.  It allows a check against the @bprm->cred->security value
 *      which was set in the preceding creds_for_exec call.  The argv list and
 *      envp list are reliably available in @bprm.  This hook may be called
 *      multiple times during a single execve.
 *      @bprm contains the linux_binprm structure.
 *      Return 0 if the hook is successful and permission is granted.
 * @bprm_committing_creds:
 *      Prepare to install the new security attributes of a process being
 *      transformed by an execve operation, based on the old credentials
 *      pointed to by @current->cred and the information set in @bprm->cred by
 *      the bprm_creds_for_exec hook.  @bprm points to the linux_binprm
 *      structure.  This hook is a good place to perform state changes on the
 *      process such as closing open file descriptors to which access will no
 *      longer be granted when the attributes are changed.  This is called
 *      immediately before commit_creds().
 * @bprm_committed_creds:
 *      Tidy up after the installation of the new security attributes of a
 *      process being transformed by an execve operation.  The new credentials
 *      have, by this point, been set to @current->cred.  @bprm points to the
 *      linux_binprm structure.  This hook is a good place to perform state
 *      changes on the process such as clearing out non-inheritable signal
 *      state.  This is called immediately after commit_creds().
 *
 * Security hooks for mount using fs_context.
 *      [See also Documentation/filesystems/mount_api.rst]
 *
 * @fs_context_dup:
 *      Allocate and attach a security structure to sc->security.  This pointer
 *      is initialised to NULL by the caller.
 *      @fc indicates the new filesystem context.
 *      @src_fc indicates the original filesystem context.
 * @fs_context_parse_param:
 *      Userspace provided a parameter to configure a superblock.  The LSM may
 *      reject it with an error and may use it for itself, in which case it
 *      should return 0; otherwise it should return -ENOPARAM to pass it on to
 *      the filesystem.
 *      @fc indicates the filesystem context.
 *      @param The parameter
 *
 * Security hooks for filesystem operations.
 *
 * @sb_alloc_security:
 *      Allocate and attach a security structure to the sb->s_security field.
 *      The s_security field is initialized to NULL when the structure is
 *      allocated.
 *      @sb contains the super_block structure to be modified.
 *      Return 0 if operation was successful.
 * @sb_delete:
 *      Release objects tied to a superblock (e.g. inodes).
 *      @sb contains the super_block structure being released.
 * @sb_free_security:
 *      Deallocate and clear the sb->s_security field.
 *      @sb contains the super_block structure to be modified.
 * @sb_free_mnt_opts:
 *      Free memory associated with @mnt_ops.
 * @sb_eat_lsm_opts:
 *      Eat (scan @orig options) and save them in @mnt_opts.
 * @sb_statfs:
 *      Check permission before obtaining filesystem statistics for the @mnt
 *      mountpoint.
 *      @dentry is a handle on the superblock for the filesystem.
 *      Return 0 if permission is granted.
 * @sb_mount:
 *      Check permission before an object specified by @dev_name is mounted on
 *      the mount point named by @nd.  For an ordinary mount, @dev_name
 *      identifies a device if the file system type requires a device.  For a
 *      remount (@flags & MS_REMOUNT), @dev_name is irrelevant.  For a
 *      loopback/bind mount (@flags & MS_BIND), @dev_name identifies the
 *      pathname of the object being mounted.
 *      @dev_name contains the name for object being mounted.
 *      @path contains the path for mount point object.
 *      @type contains the filesystem type.
 *      @flags contains the mount flags.
 *      @data contains the filesystem-specific data.
 *      Return 0 if permission is granted.
 * @sb_copy_data:
 *      Allow mount option data to be copied prior to parsing by the filesystem,
 *      so that the security module can extract security-specific mount
 *      options cleanly (a filesystem may modify the data e.g. with strsep()).
 *      This also allows the original mount data to be stripped of security-
 *      specific options to avoid having to make filesystems aware of them.
 *      @orig the original mount data copied from userspace.
 *      @copy copied data which will be passed to the security module.
 *      Returns 0 if the copy was successful.
 * @sb_mnt_opts_compat:
 *      Determine if the new mount options in @mnt_opts are allowed given
 *      the existing mounted filesystem at @sb.
 *      @sb superblock being compared
 *      @mnt_opts new mount options
 *      Return 0 if options are compatible.
 * @sb_remount:
 *      Extracts security system specific mount options and verifies no changes
 *      are being made to those options.
 *      @sb superblock being remounted
 *      @data contains the filesystem-specific data.
 *      Return 0 if permission is granted.
 * @sb_kern_mount:
 *      Mount this @sb if allowed by permissions.
 * @sb_show_options:
 *      Show (print on @m) mount options for this @sb.
 * @sb_umount:
 *      Check permission before the @mnt file system is unmounted.
 *      @mnt contains the mounted file system.
 *      @flags contains the unmount flags, e.g. MNT_FORCE.
 *      Return 0 if permission is granted.
 * @sb_pivotroot:
 *      Check permission before pivoting the root filesystem.
 *      @old_path contains the path for the new location of the
 *      current root (put_old).
 *      @new_path contains the path for the new root (new_root).
 *      Return 0 if permission is granted.
 * @sb_set_mnt_opts:
 *      Set the security relevant mount options used for a superblock
 *      @sb the superblock to set security mount options for
 *      @opts binary data structure containing all lsm mount data
 * @sb_clone_mnt_opts:
 *      Copy all security options from a given superblock to another
 *      @oldsb old superblock which contain information to clone
 *      @newsb new superblock which needs filled in
 * @sb_add_mnt_opt:
 *      Add one mount @option to @mnt_opts.
 * @sb_parse_opts_str:
 *      Parse a string of security data filling in the opts structure
 *      @options string containing all mount options known by the LSM
 *      @opts binary data structure usable by the LSM
 * @move_mount:
 *      Check permission before a mount is moved.
 *      @from_path indicates the mount that is going to be moved.
 *      @to_path indicates the mountpoint that will be mounted upon.
 * @dentry_init_security:
 *      Compute a context for a dentry as the inode is not yet available
 *      since NFSv4 has no label backed by an EA anyway.
 *      @dentry dentry to use in calculating the context.
 *      @mode mode used to determine resource type.
 *      @name name of the last path component used to create file
 *      @ctx pointer to place the pointer to the resulting context in.
 *      @ctxlen point to place the length of the resulting context.
 * @dentry_create_files_as:
 *      Compute a context for a dentry as the inode is not yet available
 *      and set that context in passed in creds so that new files are
 *      created using that context. Context is calculated using the
 *      passed in creds and not the creds of the caller.
 *      @dentry dentry to use in calculating the context.
 *      @mode mode used to determine resource type.
 *      @name name of the last path component used to create file
 *      @old creds which should be used for context calculation
 *      @new creds to modify
 *
 *
 * Security hooks for inode operations.
 *
 * @inode_alloc_security:
 *      Allocate and attach a security structure to @inode->i_security.  The
 *      i_security field is initialized to NULL when the inode structure is
 *      allocated.
 *      @inode contains the inode structure.
 *      Return 0 if operation was successful.
 * @inode_free_security:
 *      @inode contains the inode structure.
 *      Deallocate the inode security structure and set @inode->i_security to
 *      NULL.
 * @inode_init_security:
 *      Obtain the security attribute name suffix and value to set on a newly
 *      created inode and set up the incore security field for the new inode.
 *      This hook is called by the fs code as part of the inode creation
 *      transaction and provides for atomic labeling of the inode, unlike
 *      the post_create/mkdir/... hooks called by the VFS.  The hook function
 *      is expected to allocate the name and value via kmalloc, with the caller
 *      being responsible for calling kfree after using them.
 *      If the security module does not use security attributes or does
 *      not wish to put a security attribute on this particular inode,
 *      then it should return -EOPNOTSUPP to skip this processing.
 *      @inode contains the inode structure of the newly created inode.
 *      @dir contains the inode structure of the parent directory.
 *      @qstr contains the last path component of the new object
 *      @name will be set to the allocated name suffix (e.g. selinux).
 *      @value will be set to the allocated attribute value.
 *      @len will be set to the length of the value.
 *      Returns 0 if @name and @value have been successfully set,
 *      -EOPNOTSUPP if no security attribute is needed, or
 *      -ENOMEM on memory allocation failure.
 * @inode_init_security_anon:
 *      Set up the incore security field for the new anonymous inode
 *      and return whether the inode creation is permitted by the security
 *      module or not.
 *      @inode contains the inode structure
 *      @name name of the anonymous inode class
 *      @context_inode optional related inode
 *      Returns 0 on success, -EACCES if the security module denies the
 *      creation of this inode, or another -errno upon other errors.
 * @inode_create:
 *      Check permission to create a regular file.
 *      @dir contains inode structure of the parent of the new file.
 *      @dentry contains the dentry structure for the file to be created.
 *      @mode contains the file mode of the file to be created.
 *      Return 0 if permission is granted.
 * @inode_link:
 *      Check permission before creating a new hard link to a file.
 *      @old_dentry contains the dentry structure for an existing
 *      link to the file.
 *      @dir contains the inode structure of the parent directory
 *      of the new link.
 *      @new_dentry contains the dentry structure for the new link.
 *      Return 0 if permission is granted.
 * @path_link:
 *      Check permission before creating a new hard link to a file.
 *      @old_dentry contains the dentry structure for an existing link
 *      to the file.
 *      @new_dir contains the path structure of the parent directory of
 *      the new link.
 *      @new_dentry contains the dentry structure for the new link.
 *      Return 0 if permission is granted.
 * @inode_unlink:
 *      Check the permission to remove a hard link to a file.
 *      @dir contains the inode structure of parent directory of the file.
 *      @dentry contains the dentry structure for file to be unlinked.
 *      Return 0 if permission is granted.
 * @path_unlink:
 *      Check the permission to remove a hard link to a file.
 *      @dir contains the path structure of parent directory of the file.
 *      @dentry contains the dentry structure for file to be unlinked.
 *      Return 0 if permission is granted.
 * @inode_symlink:
 *      Check the permission to create a symbolic link to a file.
 *      @dir contains the inode structure of parent directory of
 *      the symbolic link.
 *      @dentry contains the dentry structure of the symbolic link.
 *      @old_name contains the pathname of file.
 *      Return 0 if permission is granted.
 * @path_symlink:
 *      Check the permission to create a symbolic link to a file.
 *      @dir contains the path structure of parent directory of
 *      the symbolic link.
 *      @dentry contains the dentry structure of the symbolic link.
 *      @old_name contains the pathname of file.
 *      Return 0 if permission is granted.
 * @inode_mkdir:
 *      Check permissions to create a new directory in the existing directory
 *      associated with inode structure @dir.
 *      @dir contains the inode structure of parent of the directory
 *      to be created.
 *      @dentry contains the dentry structure of new directory.
 *      @mode contains the mode of new directory.
 *      Return 0 if permission is granted.
 * @path_mkdir:
 *      Check permissions to create a new directory in the existing directory
 *      associated with path structure @path.
 *      @dir contains the path structure of parent of the directory
 *      to be created.
 *      @dentry contains the dentry structure of new directory.
 *      @mode contains the mode of new directory.
 *      Return 0 if permission is granted.
 * @inode_rmdir:
 *      Check the permission to remove a directory.
 *      @dir contains the inode structure of parent of the directory
 *      to be removed.
 *      @dentry contains the dentry structure of directory to be removed.
 *      Return 0 if permission is granted.
 * @path_rmdir:
 *      Check the permission to remove a directory.
 *      @dir contains the path structure of parent of the directory to be
 *      removed.
 *      @dentry contains the dentry structure of directory to be removed.
 *      Return 0 if permission is granted.
 * @inode_mknod:
 *      Check permissions when creating a special file (or a socket or a fifo
 *      file created via the mknod system call).  Note that if mknod operation
 *      is being done for a regular file, then the create hook will be called
 *      and not this hook.
 *      @dir contains the inode structure of parent of the new file.
 *      @dentry contains the dentry structure of the new file.
 *      @mode contains the mode of the new file.
 *      @dev contains the device number.
 *      Return 0 if permission is granted.
 * @path_mknod:
 *      Check permissions when creating a file. Note that this hook is called
 *      even if mknod operation is being done for a regular file.
 *      @dir contains the path structure of parent of the new file.
 *      @dentry contains the dentry structure of the new file.
 *      @mode contains the mode of the new file.
 *      @dev contains the undecoded device number. Use new_decode_dev() to get
 *      the decoded device number.
 *      Return 0 if permission is granted.
 * @inode_rename:
 *      Check for permission to rename a file or directory.
 *      @old_dir contains the inode structure for parent of the old link.
 *      @old_dentry contains the dentry structure of the old link.
 *      @new_dir contains the inode structure for parent of the new link.
 *      @new_dentry contains the dentry structure of the new link.
 *      Return 0 if permission is granted.
 * @path_rename:
 *      Check for permission to rename a file or directory.
 *      @old_dir contains the path structure for parent of the old link.
 *      @old_dentry contains the dentry structure of the old link.
 *      @new_dir contains the path structure for parent of the new link.
 *      @new_dentry contains the dentry structure of the new link.
 *      Return 0 if permission is granted.
 * @path_chmod:
 *      Check for permission to change a mode of the file @path. The new
 *      mode is specified in @mode.
 *      @path contains the path structure of the file to change the mode.
 *      @mode contains the new DAC's permission, which is a bitmask of
 *      constants from <include/uapi/linux/stat.h>
 *      Return 0 if permission is granted.
 * @path_chown:
 *      Check for permission to change owner/group of a file or directory.
 *      @path contains the path structure.
 *      @uid contains new owner's ID.
 *      @gid contains new group's ID.
 *      Return 0 if permission is granted.
 * @path_chroot:
 *      Check for permission to change root directory.
 *      @path contains the path structure.
 *      Return 0 if permission is granted.
 * @path_notify:
 *      Check permissions before setting a watch on events as defined by @mask,
 *      on an object at @path, whose type is defined by @obj_type.
 * @inode_readlink:
 *      Check the permission to read the symbolic link.
 *      @dentry contains the dentry structure for the file link.
 *      Return 0 if permission is granted.
 * @inode_follow_link:
 *      Check permission to follow a symbolic link when looking up a pathname.
 *      @dentry contains the dentry structure for the link.
 *      @inode contains the inode, which itself is not stable in RCU-walk
 *      @rcu indicates whether we are in RCU-walk mode.
 *      Return 0 if permission is granted.
 * @inode_permission:
 *      Check permission before accessing an inode.  This hook is called by the
 *      existing Linux permission function, so a security module can use it to
 *      provide additional checking for existing Linux permission checks.
 *      Notice that this hook is called when a file is opened (as well as many
 *      other operations), whereas the file_security_ops permission hook is
 *      called when the actual read/write operations are performed.
 *      @inode contains the inode structure to check.
 *      @mask contains the permission mask.
 *      Return 0 if permission is granted.
 * @inode_setattr:
 *      Check permission before setting file attributes.  Note that the kernel
 *      call to notify_change is performed from several locations, whenever
 *      file attributes change (such as when a file is truncated, chown/chmod
 *      operations, transferring disk quotas, etc).
 *      @dentry contains the dentry structure for the file.
 *      @attr is the iattr structure containing the new file attributes.
 *      Return 0 if permission is granted.
 * @path_truncate:
 *      Check permission before truncating a file.
 *      @path contains the path structure for the file.
 *      Return 0 if permission is granted.
 * @inode_getattr:
 *      Check permission before obtaining file attributes.
 *      @path contains the path structure for the file.
 *      Return 0 if permission is granted.
 * @inode_setxattr:
 *      Check permission before setting the extended attributes
 *      @value identified by @name for @dentry.
 *      Return 0 if permission is granted.
 * @inode_post_setxattr:
 *      Update inode security field after successful setxattr operation.
 *      @value identified by @name for @dentry.
 * @inode_getxattr:
 *      Check permission before obtaining the extended attributes
 *      identified by @name for @dentry.
 *      Return 0 if permission is granted.
 * @inode_listxattr:
 *      Check permission before obtaining the list of extended attribute
 *      names for @dentry.
 *      Return 0 if permission is granted.
 * @inode_removexattr:
 *      Check permission before removing the extended attribute
 *      identified by @name for @dentry.
 *      Return 0 if permission is granted.
 * @inode_getsecurity:
 *      Retrieve a copy of the extended attribute representation of the
 *      security label associated with @name for @inode via @buffer.  Note that
 *      @name is the remainder of the attribute name after the security prefix
 *      has been removed. @alloc is used to specify of the call should return a
 *      value via the buffer or just the value length Return size of buffer on
 *      success.
 * @inode_setsecurity:
 *      Set the security label associated with @name for @inode from the
 *      extended attribute value @value.  @size indicates the size of the
 *      @value in bytes.  @flags may be XATTR_CREATE, XATTR_REPLACE, or 0.
 *      Note that @name is the remainder of the attribute name after the
 *      security. prefix has been removed.
 *      Return 0 on success.
 * @inode_listsecurity:
 *      Copy the extended attribute names for the security labels
 *      associated with @inode into @buffer.  The maximum size of @buffer
 *      is specified by @buffer_size.  @buffer may be NULL to request
 *      the size of the buffer required.
 *      Returns number of bytes used/required on success.
 * @inode_need_killpriv:
 *      Called when an inode has been changed.
 *      @dentry is the dentry being changed.
 *      Return <0 on error to abort the inode change operation.
 *      Return 0 if inode_killpriv does not need to be called.
 *      Return >0 if inode_killpriv does need to be called.
 * @inode_killpriv:
 *      The setuid bit is being removed.  Remove similar security labels.
 *      Called with the dentry->d_inode->i_mutex held.
 *      @mnt_userns: user namespace of the mount
 *      @dentry is the dentry being changed.
 *      Return 0 on success.  If error is returned, then the operation
 *      causing setuid bit removal is failed.
 * @inode_getsecid:
 *      Get the secid associated with the node.
 *      @inode contains a pointer to the inode.
 *      @secid contains a pointer to the location where result will be saved.
 *      In case of failure, @secid will be set to zero.
 * @inode_copy_up:
 *      A file is about to be copied up from lower layer to upper layer of
 *      overlay filesystem. Security module can prepare a set of new creds
 *      and modify as need be and return new creds. Caller will switch to
 *      new creds temporarily to create new file and release newly allocated
 *      creds.
 *      @src indicates the union dentry of file that is being copied up.
 *      @new pointer to pointer to return newly allocated creds.
 *      Returns 0 on success or a negative error code on error.
 * @inode_copy_up_xattr:
 *      Filter the xattrs being copied up when a unioned file is copied
 *      up from a lower layer to the union/overlay layer.
 *      @name indicates the name of the xattr.
 *      Returns 0 to accept the xattr, 1 to discard the xattr, -EOPNOTSUPP if
 *      security module does not know about attribute or a negative error code
 *      to abort the copy up. Note that the caller is responsible for reading
 *      and writing the xattrs as this hook is merely a filter.
 * @d_instantiate:
 *      Fill in @inode security information for a @dentry if allowed.
 * @getprocattr:
 *      Read attribute @name for process @p and store it into @value if allowed.
 * @setprocattr:
 *      Write (set) attribute @name to @value, size @size if allowed.
 *
 * Security hooks for kernfs node operations
 *
 * @kernfs_init_security:
 *      Initialize the security context of a newly created kernfs node based
 *      on its own and its parent's attributes.
 *
 *      @kn_dir the parent kernfs node
 *      @kn the new child kernfs node
 *
 * Security hooks for file operations
 *
 * @file_permission:
 *      Check file permissions before accessing an open file.  This hook is
 *      called by various operations that read or write files.  A security
 *      module can use this hook to perform additional checking on these
 *      operations, e.g.  to revalidate permissions on use to support privilege
 *      bracketing or policy changes.  Notice that this hook is used when the
 *      actual read/write operations are performed, whereas the
 *      inode_security_ops hook is called when a file is opened (as well as
 *      many other operations).
 *      Caveat:  Although this hook can be used to revalidate permissions for
 *      various system call operations that read or write files, it does not
 *      address the revalidation of permissions for memory-mapped files.
 *      Security modules must handle this separately if they need such
 *      revalidation.
 *      @file contains the file structure being accessed.
 *      @mask contains the requested permissions.
 *      Return 0 if permission is granted.
 * @file_alloc_security:
 *      Allocate and attach a security structure to the file->f_security field.
 *      The security field is initialized to NULL when the structure is first
 *      created.
 *      @file contains the file structure to secure.
 *      Return 0 if the hook is successful and permission is granted.
 * @file_free_security:
 *      Deallocate and free any security structures stored in file->f_security.
 *      @file contains the file structure being modified.
 * @file_ioctl:
 *      @file contains the file structure.
 *      @cmd contains the operation to perform.
 *      @arg contains the operational arguments.
 *      Check permission for an ioctl operation on @file.  Note that @arg
 *      sometimes represents a user space pointer; in other cases, it may be a
 *      simple integer value.  When @arg represents a user space pointer, it
 *      should never be used by the security module.
 *      Return 0 if permission is granted.
 * @mmap_addr :
 *      Check permissions for a mmap operation at @addr.
 *      @addr contains virtual address that will be used for the operation.
 *      Return 0 if permission is granted.
 * @mmap_file :
 *      Check permissions for a mmap operation.  The @file may be NULL, e.g.
 *      if mapping anonymous memory.
 *      @file contains the file structure for file to map (may be NULL).
 *      @reqprot contains the protection requested by the application.
 *      @prot contains the protection that will be applied by the kernel.
 *      @flags contains the operational flags.
 *      Return 0 if permission is granted.
 * @file_mprotect:
 *      Check permissions before changing memory access permissions.
 *      @vma contains the memory region to modify.
 *      @reqprot contains the protection requested by the application.
 *      @prot contains the protection that will be applied by the kernel.
 *      Return 0 if permission is granted.
 * @file_lock:
 *      Check permission before performing file locking operations.
 *      Note the hook mediates both flock and fcntl style locks.
 *      @file contains the file structure.
 *      @cmd contains the posix-translated lock operation to perform
 *      (e.g. F_RDLCK, F_WRLCK).
 *      Return 0 if permission is granted.
 * @file_fcntl:
 *      Check permission before allowing the file operation specified by @cmd
 *      from being performed on the file @file.  Note that @arg sometimes
 *      represents a user space pointer; in other cases, it may be a simple
 *      integer value.  When @arg represents a user space pointer, it should
 *      never be used by the security module.
 *      @file contains the file structure.
 *      @cmd contains the operation to be performed.
 *      @arg contains the operational arguments.
 *      Return 0 if permission is granted.
 * @file_set_fowner:
 *      Save owner security information (typically from current->security) in
 *      file->f_security for later use by the send_sigiotask hook.
 *      @file contains the file structure to update.
 *      Return 0 on success.
 * @file_send_sigiotask:
 *      Check permission for the file owner @fown to send SIGIO or SIGURG to the
 *      process @tsk.  Note that this hook is sometimes called from interrupt.
 *      Note that the fown_struct, @fown, is never outside the context of a
 *      struct file, so the file structure (and associated security information)
 *      can always be obtained: container_of(fown, struct file, f_owner)
 *      @tsk contains the structure of task receiving signal.
 *      @fown contains the file owner information.
 *      @sig is the signal that will be sent.  When 0, kernel sends SIGIO.
 *      Return 0 if permission is granted.
 * @file_receive:
 *      This hook allows security modules to control the ability of a process
 *      to receive an open file descriptor via socket IPC.
 *      @file contains the file structure being received.
 *      Return 0 if permission is granted.
 * @file_open:
 *      Save open-time permission checking state for later use upon
 *      file_permission, and recheck access if anything has changed
 *      since inode_permission.
 *
 * Security hooks for task operations.
 *
 * @task_alloc:
 *      @task task being allocated.
 *      @clone_flags contains the flags indicating what should be shared.
 *      Handle allocation of task-related resources.
 *      Returns a zero on success, negative values on failure.
 * @task_free:
 *      @task task about to be freed.
 *      Handle release of task-related resources. (Note that this can be called
 *      from interrupt context.)
 * @cred_alloc_blank:
 *      @cred points to the credentials.
 *      @gfp indicates the atomicity of any memory allocations.
 *      Only allocate sufficient memory and attach to @cred such that
 *      cred_transfer() will not get ENOMEM.
 * @cred_free:
 *      @cred points to the credentials.
 *      Deallocate and clear the cred->security field in a set of credentials.
 * @cred_prepare:
 *      @new points to the new credentials.
 *      @old points to the original credentials.
 *      @gfp indicates the atomicity of any memory allocations.
 *      Prepare a new set of credentials by copying the data from the old set.
 * @cred_transfer:
 *      @new points to the new credentials.
 *      @old points to the original credentials.
 *      Transfer data from original creds to new creds
 * @cred_getsecid:
 *      Retrieve the security identifier of the cred structure @c
 *      @c contains the credentials, secid will be placed into @secid.
 *      In case of failure, @secid will be set to zero.
 * @kernel_act_as:
 *      Set the credentials for a kernel service to act as (subjective context).
 *      @new points to the credentials to be modified.
 *      @secid specifies the security ID to be set
 *      The current task must be the one that nominated @secid.
 *      Return 0 if successful.
 * @kernel_create_files_as:
 *      Set the file creation context in a set of credentials to be the same as
 *      the objective context of the specified inode.
 *      @new points to the credentials to be modified.
 *      @inode points to the inode to use as a reference.
 *      The current task must be the one that nominated @inode.
 *      Return 0 if successful.
 * @kernel_module_request:
 *      Ability to trigger the kernel to automatically upcall to userspace for
 *      userspace to load a kernel module with the given name.
 *      @kmod_name name of the module requested by the kernel
 *      Return 0 if successful.
 * @kernel_load_data:
 *      Load data provided by userspace.
 *      @id kernel load data identifier
 *      @contents if a subsequent @kernel_post_load_data will be called.
 *      Return 0 if permission is granted.
 * @kernel_post_load_data:
 *      Load data provided by a non-file source (usually userspace buffer).
 *      @buf pointer to buffer containing the data contents.
 *      @size length of the data contents.
 *      @id kernel load data identifier
 *      @description a text description of what was loaded, @id-specific
 *      Return 0 if permission is granted.
 *      This must be paired with a prior @kernel_load_data call that had
 *      @contents set to true.
 * @kernel_read_file:
 *      Read a file specified by userspace.
 *      @file contains the file structure pointing to the file being read
 *      by the kernel.
 *      @id kernel read file identifier
 *      @contents if a subsequent @kernel_post_read_file will be called.
 *      Return 0 if permission is granted.
 * @kernel_post_read_file:
 *      Read a file specified by userspace.
 *      @file contains the file structure pointing to the file being read
 *      by the kernel.
 *      @buf pointer to buffer containing the file contents.
 *      @size length of the file contents.
 *      @id kernel read file identifier
 *      This must be paired with a prior @kernel_read_file call that had
 *      @contents set to true.
 *      Return 0 if permission is granted.
 * @task_fix_setuid:
 *      Update the module's state after setting one or more of the user
 *      identity attributes of the current process.  The @flags parameter
 *      indicates which of the set*uid system calls invoked this hook.  If
 *      @new is the set of credentials that will be installed.  Modifications
 *      should be made to this rather than to @current->cred.
 *      @old is the set of credentials that are being replaces
 *      @flags contains one of the LSM_SETID_* values.
 *      Return 0 on success.
 * @task_fix_setgid:
 *      Update the module's state after setting one or more of the group
 *      identity attributes of the current process.  The @flags parameter
 *      indicates which of the set*gid system calls invoked this hook.
 *      @new is the set of credentials that will be installed.  Modifications
 *      should be made to this rather than to @current->cred.
 *      @old is the set of credentials that are being replaced.
 *      @flags contains one of the LSM_SETID_* values.
 *      Return 0 on success.
 * @task_setpgid:
 *      Check permission before setting the process group identifier of the
 *      process @p to @pgid.
 *      @p contains the task_struct for process being modified.
 *      @pgid contains the new pgid.
 *      Return 0 if permission is granted.
 * @task_getpgid:
 *      Check permission before getting the process group identifier of the
 *      process @p.
 *      @p contains the task_struct for the process.
 *      Return 0 if permission is granted.
 * @task_getsid:
 *      Check permission before getting the session identifier of the process
 *      @p.
 *      @p contains the task_struct for the process.
 *      Return 0 if permission is granted.
 * @task_getsecid_subj:
 *      Retrieve the subjective security identifier of the task_struct in @p
 *      and return it in @secid.  Special care must be taken to ensure that @p
 *      is the either the "current" task, or the caller has exclusive access
 *      to @p.
 *      In case of failure, @secid will be set to zero.
 * @task_getsecid_obj:
 *      Retrieve the objective security identifier of the task_struct in @p
 *      and return it in @secid.
 *      In case of failure, @secid will be set to zero.
 *
 * @task_setnice:
 *      Check permission before setting the nice value of @p to @nice.
 *      @p contains the task_struct of process.
 *      @nice contains the new nice value.
 *      Return 0 if permission is granted.
 * @task_setioprio:
 *      Check permission before setting the ioprio value of @p to @ioprio.
 *      @p contains the task_struct of process.
 *      @ioprio contains the new ioprio value
 *      Return 0 if permission is granted.
 * @task_getioprio:
 *      Check permission before getting the ioprio value of @p.
 *      @p contains the task_struct of process.
 *      Return 0 if permission is granted.
 * @task_prlimit:
 *      Check permission before getting and/or setting the resource limits of
 *      another task.
 *      @cred points to the cred structure for the current task.
 *      @tcred points to the cred structure for the target task.
 *      @flags contains the LSM_PRLIMIT_* flag bits indicating whether the
 *      resource limits are being read, modified, or both.
 *      Return 0 if permission is granted.
 * @task_setrlimit:
 *      Check permission before setting the resource limits of process @p
 *      for @resource to @new_rlim.  The old resource limit values can
 *      be examined by dereferencing (p->signal->rlim + resource).
 *      @p points to the task_struct for the target task's group leader.
 *      @resource contains the resource whose limit is being set.
 *      @new_rlim contains the new limits for @resource.
 *      Return 0 if permission is granted.
 * @task_setscheduler:
 *      Check permission before setting scheduling policy and/or parameters of
 *      process @p.
 *      @p contains the task_struct for process.
 *      Return 0 if permission is granted.
 * @task_getscheduler:
 *      Check permission before obtaining scheduling information for process
 *      @p.
 *      @p contains the task_struct for process.
 *      Return 0 if permission is granted.
 * @task_movememory:
 *      Check permission before moving memory owned by process @p.
 *      @p contains the task_struct for process.
 *      Return 0 if permission is granted.
 * @task_kill:
 *      Check permission before sending signal @sig to @p.  @info can be NULL,
 *      the constant 1, or a pointer to a kernel_siginfo structure.  If @info is 1 or
 *      SI_FROMKERNEL(info) is true, then the signal should be viewed as coming
 *      from the kernel and should typically be permitted.
 *      SIGIO signals are handled separately by the send_sigiotask hook in
 *      file_security_ops.
 *      @p contains the task_struct for process.
 *      @info contains the signal information.
 *      @sig contains the signal value.
 *      @cred contains the cred of the process where the signal originated, or
 *      NULL if the current task is the originator.
 *      Return 0 if permission is granted.
 * @task_prctl:
 *      Check permission before performing a process control operation on the
 *      current process.
 *      @option contains the operation.
 *      @arg2 contains a argument.
 *      @arg3 contains a argument.
 *      @arg4 contains a argument.
 *      @arg5 contains a argument.
 *      Return -ENOSYS if no-one wanted to handle this op, any other value to
 *      cause prctl() to return immediately with that value.
 * @task_to_inode:
 *      Set the security attributes for an inode based on an associated task's
 *      security attributes, e.g. for /proc/pid inodes.
 *      @p contains the task_struct for the task.
 *      @inode contains the inode structure for the inode.
 *
 * Security hooks for Netlink messaging.
 *
 * @netlink_send:
 *      Save security information for a netlink message so that permission
 *      checking can be performed when the message is processed.  The security
 *      information can be saved using the eff_cap field of the
 *      netlink_skb_parms structure.  Also may be used to provide fine
 *      grained control over message transmission.
 *      @sk associated sock of task sending the message.
 *      @skb contains the sk_buff structure for the netlink message.
 *      Return 0 if the information was successfully saved and message
 *      is allowed to be transmitted.
 *
 * Security hooks for Unix domain networking.
 *
 * @unix_stream_connect:
 *      Check permissions before establishing a Unix domain stream connection
 *      between @sock and @other.
 *      @sock contains the sock structure.
 *      @other contains the peer sock structure.
 *      @newsk contains the new sock structure.
 *      Return 0 if permission is granted.
 * @unix_may_send:
 *      Check permissions before connecting or sending datagrams from @sock to
 *      @other.
 *      @sock contains the socket structure.
 *      @other contains the peer socket structure.
 *      Return 0 if permission is granted.
 *
 * The @unix_stream_connect and @unix_may_send hooks were necessary because
 * Linux provides an alternative to the conventional file name space for Unix
 * domain sockets.  Whereas binding and connecting to sockets in the file name
 * space is mediated by the typical file permissions (and caught by the mknod
 * and permission hooks in inode_security_ops), binding and connecting to
 * sockets in the abstract name space is completely unmediated.  Sufficient
 * control of Unix domain sockets in the abstract name space isn't possible
 * using only the socket layer hooks, since we need to know the actual target
 * socket, which is not looked up until we are inside the af_unix code.
 *
 * Security hooks for socket operations.
 *
 * @socket_create:
 *      Check permissions prior to creating a new socket.
 *      @family contains the requested protocol family.
 *      @type contains the requested communications type.
 *      @protocol contains the requested protocol.
 *      @kern set to 1 if a kernel socket.
 *      Return 0 if permission is granted.
 * @socket_post_create:
 *      This hook allows a module to update or allocate a per-socket security
 *      structure. Note that the security field was not added directly to the
 *      socket structure, but rather, the socket security information is stored
 *      in the associated inode.  Typically, the inode alloc_security hook will
 *      allocate and attach security information to
 *      SOCK_INODE(sock)->i_security.  This hook may be used to update the
 *      SOCK_INODE(sock)->i_security field with additional information that
 *      wasn't available when the inode was allocated.
 *      @sock contains the newly created socket structure.
 *      @family contains the requested protocol family.
 *      @type contains the requested communications type.
 *      @protocol contains the requested protocol.
 *      @kern set to 1 if a kernel socket.
 * @socket_socketpair:
 *      Check permissions before creating a fresh pair of sockets.
 *      @socka contains the first socket structure.
 *      @sockb contains the second socket structure.
 *      Return 0 if permission is granted and the connection was established.
 * @socket_bind:
 *      Check permission before socket protocol layer bind operation is
 *      performed and the socket @sock is bound to the address specified in the
 *      @address parameter.
 *      @sock contains the socket structure.
 *      @address contains the address to bind to.
 *      @addrlen contains the length of address.
 *      Return 0 if permission is granted.
 * @socket_connect:
 *      Check permission before socket protocol layer connect operation
 *      attempts to connect socket @sock to a remote address, @address.
 *      @sock contains the socket structure.
 *      @address contains the address of remote endpoint.
 *      @addrlen contains the length of address.
 *      Return 0 if permission is granted.
 * @socket_listen:
 *      Check permission before socket protocol layer listen operation.
 *      @sock contains the socket structure.
 *      @backlog contains the maximum length for the pending connection queue.
 *      Return 0 if permission is granted.
 * @socket_accept:
 *      Check permission before accepting a new connection.  Note that the new
 *      socket, @newsock, has been created and some information copied to it,
 *      but the accept operation has not actually been performed.
 *      @sock contains the listening socket structure.
 *      @newsock contains the newly created server socket for connection.
 *      Return 0 if permission is granted.
 * @socket_sendmsg:
 *      Check permission before transmitting a message to another socket.
 *      @sock contains the socket structure.
 *      @msg contains the message to be transmitted.
 *      @size contains the size of message.
 *      Return 0 if permission is granted.
 * @socket_recvmsg:
 *      Check permission before receiving a message from a socket.
 *      @sock contains the socket structure.
 *      @msg contains the message structure.
 *      @size contains the size of message structure.
 *      @flags contains the operational flags.
 *      Return 0 if permission is granted.
 * @socket_getsockname:
 *      Check permission before the local address (name) of the socket object
 *      @sock is retrieved.
 *      @sock contains the socket structure.
 *      Return 0 if permission is granted.
 * @socket_getpeername:
 *      Check permission before the remote address (name) of a socket object
 *      @sock is retrieved.
 *      @sock contains the socket structure.
 *      Return 0 if permission is granted.
 * @socket_getsockopt:
 *      Check permissions before retrieving the options associated with socket
 *      @sock.
 *      @sock contains the socket structure.
 *      @level contains the protocol level to retrieve option from.
 *      @optname contains the name of option to retrieve.
 *      Return 0 if permission is granted.
 * @socket_setsockopt:
 *      Check permissions before setting the options associated with socket
 *      @sock.
 *      @sock contains the socket structure.
 *      @level contains the protocol level to set options for.
 *      @optname contains the name of the option to set.
 *      Return 0 if permission is granted.
 * @socket_shutdown:
 *      Checks permission before all or part of a connection on the socket
 *      @sock is shut down.
 *      @sock contains the socket structure.
 *      @how contains the flag indicating how future sends and receives
 *      are handled.
 *      Return 0 if permission is granted.
 * @socket_sock_rcv_skb:
 *      Check permissions on incoming network packets.  This hook is distinct
 *      from Netfilter's IP input hooks since it is the first time that the
 *      incoming sk_buff @skb has been associated with a particular socket, @sk.
 *      Must not sleep inside this hook because some callers hold spinlocks.
 *      @sk contains the sock (not socket) associated with the incoming sk_buff.
 *      @skb contains the incoming network data.
 * @socket_getpeersec_stream:
 *      This hook allows the security module to provide peer socket security
 *      state for unix or connected tcp sockets to userspace via getsockopt
 *      SO_GETPEERSEC.  For tcp sockets this can be meaningful if the
 *      socket is associated with an ipsec SA.
 *      @sock is the local socket.
 *      @optval userspace memory where the security state is to be copied.
 *      @optlen userspace int where the module should copy the actual length
 *      of the security state.
 *      @len as input is the maximum length to copy to userspace provided
 *      by the caller.
 *      Return 0 if all is well, otherwise, typical getsockopt return
 *      values.
 * @socket_getpeersec_dgram:
 *      This hook allows the security module to provide peer socket security
 *      state for udp sockets on a per-packet basis to userspace via
 *      getsockopt SO_GETPEERSEC. The application must first have indicated
 *      the IP_PASSSEC option via getsockopt. It can then retrieve the
 *      security state returned by this hook for a packet via the SCM_SECURITY
 *      ancillary message type.
 *      @sock contains the peer socket. May be NULL.
 *      @skb is the sk_buff for the packet being queried. May be NULL.
 *      @secid pointer to store the secid of the packet.
 *      Return 0 on success, error on failure.
 * @sk_alloc_security:
 *      Allocate and attach a security structure to the sk->sk_security field,
 *      which is used to copy security attributes between local stream sockets.
 * @sk_free_security:
 *      Deallocate security structure.
 * @sk_clone_security:
 *      Clone/copy security structure.
 * @sk_getsecid:
 *      Retrieve the LSM-specific secid for the sock to enable caching
 *      of network authorizations.
 * @sock_graft:
 *      Sets the socket's isec sid to the sock's sid.
 * @inet_conn_request:
 *      Sets the openreq's sid to socket's sid with MLS portion taken
 *      from peer sid.
 * @inet_csk_clone:
 *      Sets the new child socket's sid to the openreq sid.
 * @inet_conn_established:
 *      Sets the connection's peersid to the secmark on skb.
 * @secmark_relabel_packet:
 *      check if the process should be allowed to relabel packets to
 *      the given secid
 * @secmark_refcount_inc:
 *      tells the LSM to increment the number of secmark labeling rules loaded
 * @secmark_refcount_dec:
 *      tells the LSM to decrement the number of secmark labeling rules loaded
 * @req_classify_flow:
 *      Sets the flow's sid to the openreq sid.
 * @tun_dev_alloc_security:
 *      This hook allows a module to allocate a security structure for a TUN
 *      device.
 *      @security pointer to a security structure pointer.
 *      Returns a zero on success, negative values on failure.
 * @tun_dev_free_security:
 *      This hook allows a module to free the security structure for a TUN
 *      device.
 *      @security pointer to the TUN device's security structure
 * @tun_dev_create:
 *      Check permissions prior to creating a new TUN device.
 * @tun_dev_attach_queue:
 *      Check permissions prior to attaching to a TUN device queue.
 *      @security pointer to the TUN device's security structure.
 * @tun_dev_attach:
 *      This hook can be used by the module to update any security state
 *      associated with the TUN device's sock structure.
 *      @sk contains the existing sock structure.
 *      @security pointer to the TUN device's security structure.
 * @tun_dev_open:
 *      This hook can be used by the module to update any security state
 *      associated with the TUN device's security structure.
 *      @security pointer to the TUN devices's security structure.
 *
 * Security hooks for SCTP
 *
 * @sctp_assoc_request:
 *      Passes the @ep and @chunk->skb of the association INIT packet to
 *      the security module.
 *      @ep pointer to sctp endpoint structure.
 *      @skb pointer to skbuff of association packet.
 *      Return 0 on success, error on failure.
 * @sctp_bind_connect:
 *      Validiate permissions required for each address associated with sock
 *      @sk. Depending on @optname, the addresses will be treated as either
 *      for a connect or bind service. The @addrlen is calculated on each
 *      ipv4 and ipv6 address using sizeof(struct sockaddr_in) or
 *      sizeof(struct sockaddr_in6).
 *      @sk pointer to sock structure.
 *      @optname name of the option to validate.
 *      @address list containing one or more ipv4/ipv6 addresses.
 *      @addrlen total length of address(s).
 *      Return 0 on success, error on failure.
 * @sctp_sk_clone:
 *      Called whenever a new socket is created by accept(2) (i.e. a TCP
 *      style socket) or when a socket is 'peeled off' e.g userspace
 *      calls sctp_peeloff(3).
 *      @ep pointer to current sctp endpoint structure.
 *      @sk pointer to current sock structure.
 *      @sk pointer to new sock structure.
 *
 * Security hooks for Infiniband
 *
 * @ib_pkey_access:
 *      Check permission to access a pkey when modifing a QP.
 *      @subnet_prefix the subnet prefix of the port being used.
 *      @pkey the pkey to be accessed.
 *      @sec pointer to a security structure.
 * @ib_endport_manage_subnet:
 *      Check permissions to send and receive SMPs on a end port.
 *      @dev_name the IB device name (i.e. mlx4_0).
 *      @port_num the port number.
 *      @sec pointer to a security structure.
 * @ib_alloc_security:
 *      Allocate a security structure for Infiniband objects.
 *      @sec pointer to a security structure pointer.
 *      Returns 0 on success, non-zero on failure
 * @ib_free_security:
 *      Deallocate an Infiniband security structure.
 *      @sec contains the security structure to be freed.
 *
 * Security hooks for XFRM operations.
 *
 * @xfrm_policy_alloc_security:
 *      @ctxp is a pointer to the xfrm_sec_ctx being added to Security Policy
 *      Database used by the XFRM system.
 *      @sec_ctx contains the security context information being provided by
 *      the user-level policy update program (e.g., setkey).
 *      Allocate a security structure to the xp->security field; the security
 *      field is initialized to NULL when the xfrm_policy is allocated.
 *      Return 0 if operation was successful (memory to allocate, legal context)
 *      @gfp is to specify the context for the allocation
 * @xfrm_policy_clone_security:
 *      @old_ctx contains an existing xfrm_sec_ctx.
 *      @new_ctxp contains a new xfrm_sec_ctx being cloned from old.
 *      Allocate a security structure in new_ctxp that contains the
 *      information from the old_ctx structure.
 *      Return 0 if operation was successful (memory to allocate).
 * @xfrm_policy_free_security:
 *      @ctx contains the xfrm_sec_ctx
 *      Deallocate xp->security.
 * @xfrm_policy_delete_security:
 *      @ctx contains the xfrm_sec_ctx.
 *      Authorize deletion of xp->security.
 * @xfrm_state_alloc:
 *      @x contains the xfrm_state being added to the Security Association
 *      Database by the XFRM system.
 *      @sec_ctx contains the security context information being provided by
 *      the user-level SA generation program (e.g., setkey or racoon).
 *      Allocate a security structure to the x->security field; the security
 *      field is initialized to NULL when the xfrm_state is allocated. Set the
 *      context to correspond to sec_ctx. Return 0 if operation was successful
 *      (memory to allocate, legal context).
 * @xfrm_state_alloc_acquire:
 *      @x contains the xfrm_state being added to the Security Association
 *      Database by the XFRM system.
 *      @polsec contains the policy's security context.
 *      @secid contains the secid from which to take the mls portion of the
 *      context.
 *      Allocate a security structure to the x->security field; the security
 *      field is initialized to NULL when the xfrm_state is allocated. Set the
 *      context to correspond to secid. Return 0 if operation was successful
 *      (memory to allocate, legal context).
 * @xfrm_state_free_security:
 *      @x contains the xfrm_state.
 *      Deallocate x->security.
 * @xfrm_state_delete_security:
 *      @x contains the xfrm_state.
 *      Authorize deletion of x->security.
 * @xfrm_policy_lookup:
 *      @ctx contains the xfrm_sec_ctx for which the access control is being
 *      checked.
 *      @fl_secid contains the flow security label that is used to authorize
 *      access to the policy xp.
 *      @dir contains the direction of the flow (input or output).
 *      Check permission when a flow selects a xfrm_policy for processing
 *      XFRMs on a packet.  The hook is called when selecting either a
 *      per-socket policy or a generic xfrm policy.
 *      Return 0 if permission is granted, -ESRCH otherwise, or -errno
 *      on other errors.
 * @xfrm_state_pol_flow_match:
 *      @x contains the state to match.
 *      @xp contains the policy to check for a match.
 *      @flic contains the flowi_common struct to check for a match.
 *      Return 1 if there is a match.
 * @xfrm_decode_session:
 *      @skb points to skb to decode.
 *      @secid points to the flow key secid to set.
 *      @ckall says if all xfrms used should be checked for same secid.
 *      Return 0 if ckall is zero or all xfrms used have the same secid.
 *
 * Security hooks affecting all Key Management operations
 *
 * @key_alloc:
 *      Permit allocation of a key and assign security data. Note that key does
 *      not have a serial number assigned at this point.
 *      @key points to the key.
 *      @flags is the allocation flags
 *      Return 0 if permission is granted, -ve error otherwise.
 * @key_free:
 *      Notification of destruction; free security data.
 *      @key points to the key.
 *      No return value.
 * @key_permission:
 *      See whether a specific operational right is granted to a process on a
 *      key.
 *      @key_ref refers to the key (key pointer + possession attribute bit).
 *      @cred points to the credentials to provide the context against which to
 *      evaluate the security data on the key.
 *      @perm describes the combination of permissions required of this key.
 *      Return 0 if permission is granted, -ve error otherwise.
 * @key_getsecurity:
 *      Get a textual representation of the security context attached to a key
 *      for the purposes of honouring KEYCTL_GETSECURITY.  This function
 *      allocates the storage for the NUL-terminated string and the caller
 *      should free it.
 *      @key points to the key to be queried.
 *      @_buffer points to a pointer that should be set to point to the
 *      resulting string (if no label or an error occurs).
 *      Return the length of the string (including terminating NUL) or -ve if
 *      an error.
 *      May also return 0 (and a NULL buffer pointer) if there is no label.
 *
 * Security hooks affecting all System V IPC operations.
 *
 * @ipc_permission:
 *      Check permissions for access to IPC
 *      @ipcp contains the kernel IPC permission structure
 *      @flag contains the desired (requested) permission set
 *      Return 0 if permission is granted.
 * @ipc_getsecid:
 *      Get the secid associated with the ipc object.
 *      @ipcp contains the kernel IPC permission structure.
 *      @secid contains a pointer to the location where result will be saved.
 *      In case of failure, @secid will be set to zero.
 *
 * Security hooks for individual messages held in System V IPC message queues
 *
 * @msg_msg_alloc_security:
 *      Allocate and attach a security structure to the msg->security field.
 *      The security field is initialized to NULL when the structure is first
 *      created.
 *      @msg contains the message structure to be modified.
 *      Return 0 if operation was successful and permission is granted.
 * @msg_msg_free_security:
 *      Deallocate the security structure for this message.
 *      @msg contains the message structure to be modified.
 *
 * Security hooks for System V IPC Message Queues
 *
 * @msg_queue_alloc_security:
 *      Allocate and attach a security structure to the
 *      @perm->security field. The security field is initialized to
 *      NULL when the structure is first created.
 *      @perm contains the IPC permissions of the message queue.
 *      Return 0 if operation was successful and permission is granted.
 * @msg_queue_free_security:
 *      Deallocate security field @perm->security for the message queue.
 *      @perm contains the IPC permissions of the message queue.
 * @msg_queue_associate:
 *      Check permission when a message queue is requested through the
 *      msgget system call. This hook is only called when returning the
 *      message queue identifier for an existing message queue, not when a
 *      new message queue is created.
 *      @perm contains the IPC permissions of the message queue.
 *      @msqflg contains the operation control flags.
 *      Return 0 if permission is granted.
 * @msg_queue_msgctl:
 *      Check permission when a message control operation specified by @cmd
 *      is to be performed on the message queue with permissions @perm.
 *      The @perm may be NULL, e.g. for IPC_INFO or MSG_INFO.
 *      @perm contains the IPC permissions of the msg queue. May be NULL.
 *      @cmd contains the operation to be performed.
 *      Return 0 if permission is granted.
 * @msg_queue_msgsnd:
 *      Check permission before a message, @msg, is enqueued on the message
 *      queue with permissions @perm.
 *      @perm contains the IPC permissions of the message queue.
 *      @msg contains the message to be enqueued.
 *      @msqflg contains operational flags.
 *      Return 0 if permission is granted.
 * @msg_queue_msgrcv:
 *      Check permission before a message, @msg, is removed from the message
 *      queue. The @target task structure contains a pointer to the
 *      process that will be receiving the message (not equal to the current
 *      process when inline receives are being performed).
 *      @perm contains the IPC permissions of the message queue.
 *      @msg contains the message destination.
 *      @target contains the task structure for recipient process.
 *      @type contains the type of message requested.
 *      @mode contains the operational flags.
 *      Return 0 if permission is granted.
 *
 * Security hooks for System V Shared Memory Segments
 *
 * @shm_alloc_security:
 *      Allocate and attach a security structure to the @perm->security
 *      field. The security field is initialized to NULL when the structure is
 *      first created.
 *      @perm contains the IPC permissions of the shared memory structure.
 *      Return 0 if operation was successful and permission is granted.
 * @shm_free_security:
 *      Deallocate the security structure @perm->security for the memory segment.
 *      @perm contains the IPC permissions of the shared memory structure.
 * @shm_associate:
 *      Check permission when a shared memory region is requested through the
 *      shmget system call. This hook is only called when returning the shared
 *      memory region identifier for an existing region, not when a new shared
 *      memory region is created.
 *      @perm contains the IPC permissions of the shared memory structure.
 *      @shmflg contains the operation control flags.
 *      Return 0 if permission is granted.
 * @shm_shmctl:
 *      Check permission when a shared memory control operation specified by
 *      @cmd is to be performed on the shared memory region with permissions @perm.
 *      The @perm may be NULL, e.g. for IPC_INFO or SHM_INFO.
 *      @perm contains the IPC permissions of the shared memory structure.
 *      @cmd contains the operation to be performed.
 *      Return 0 if permission is granted.
 * @shm_shmat:
 *      Check permissions prior to allowing the shmat system call to attach the
 *      shared memory segment with permissions @perm to the data segment of the
 *      calling process. The attaching address is specified by @shmaddr.
 *      @perm contains the IPC permissions of the shared memory structure.
 *      @shmaddr contains the address to attach memory region to.
 *      @shmflg contains the operational flags.
 *      Return 0 if permission is granted.
 *
 * Security hooks for System V Semaphores
 *
 * @sem_alloc_security:
 *      Allocate and attach a security structure to the @perm->security
 *      field. The security field is initialized to NULL when the structure is
 *      first created.
 *      @perm contains the IPC permissions of the semaphore.
 *      Return 0 if operation was successful and permission is granted.
 * @sem_free_security:
 *      Deallocate security structure @perm->security for the semaphore.
 *      @perm contains the IPC permissions of the semaphore.
 * @sem_associate:
 *      Check permission when a semaphore is requested through the semget
 *      system call. This hook is only called when returning the semaphore
 *      identifier for an existing semaphore, not when a new one must be
 *      created.
 *      @perm contains the IPC permissions of the semaphore.
 *      @semflg contains the operation control flags.
 *      Return 0 if permission is granted.
 * @sem_semctl:
 *      Check permission when a semaphore operation specified by @cmd is to be
 *      performed on the semaphore. The @perm may be NULL, e.g. for
 *      IPC_INFO or SEM_INFO.
 *      @perm contains the IPC permissions of the semaphore. May be NULL.
 *      @cmd contains the operation to be performed.
 *      Return 0 if permission is granted.
 * @sem_semop:
 *      Check permissions before performing operations on members of the
 *      semaphore set. If the @alter flag is nonzero, the semaphore set
 *      may be modified.
 *      @perm contains the IPC permissions of the semaphore.
 *      @sops contains the operations to perform.
 *      @nsops contains the number of operations to perform.
 *      @alter contains the flag indicating whether changes are to be made.
 *      Return 0 if permission is granted.
 *
 * @binder_set_context_mgr:
 *      Check whether @mgr is allowed to be the binder context manager.
 *      @mgr contains the task_struct for the task being registered.
 *      Return 0 if permission is granted.
 * @binder_transaction:
 *      Check whether @from is allowed to invoke a binder transaction call
 *      to @to.
 *      @from contains the task_struct for the sending task.
 *      @to contains the task_struct for the receiving task.
 * @binder_transfer_binder:
 *      Check whether @from is allowed to transfer a binder reference to @to.
 *      @from contains the task_struct for the sending task.
 *      @to contains the task_struct for the receiving task.
 * @binder_transfer_file:
 *      Check whether @from is allowed to transfer @file to @to.
 *      @from contains the task_struct for the sending task.
 *      @file contains the struct file being transferred.
 *      @to contains the task_struct for the receiving task.
 *
 * @ptrace_access_check:
 *      Check permission before allowing the current process to trace the
 *      @child process.
 *      Security modules may also want to perform a process tracing check
 *      during an execve in the set_security or apply_creds hooks of
 *      tracing check during an execve in the bprm_set_creds hook of
 *      binprm_security_ops if the process is being traced and its security
 *      attributes would be changed by the execve.
 *      @child contains the task_struct structure for the target process.
 *      @mode contains the PTRACE_MODE flags indicating the form of access.
 *      Return 0 if permission is granted.
 * @ptrace_traceme:
 *      Check that the @parent process has sufficient permission to trace the
 *      current process before allowing the current process to present itself
 *      to the @parent process for tracing.
 *      @parent contains the task_struct structure for debugger process.
 *      Return 0 if permission is granted.
 * @capget:
 *      Get the @effective, @inheritable, and @permitted capability sets for
 *      the @target process.  The hook may also perform permission checking to
 *      determine if the current process is allowed to see the capability sets
 *      of the @target process.
 *      @target contains the task_struct structure for target process.
 *      @effective contains the effective capability set.
 *      @inheritable contains the inheritable capability set.
 *      @permitted contains the permitted capability set.
 *      Return 0 if the capability sets were successfully obtained.
 * @capset:
 *      Set the @effective, @inheritable, and @permitted capability sets for
 *      the current process.
 *      @new contains the new credentials structure for target process.
 *      @old contains the current credentials structure for target process.
 *      @effective contains the effective capability set.
 *      @inheritable contains the inheritable capability set.
 *      @permitted contains the permitted capability set.
 *      Return 0 and update @new if permission is granted.
 * @capable:
 *      Check whether the @tsk process has the @cap capability in the indicated
 *      credentials.
 *      @cred contains the credentials to use.
 *      @ns contains the user namespace we want the capability in
 *      @cap contains the capability <include/linux/capability.h>.
 *      @opts contains options for the capable check <include/linux/security.h>
 *      Return 0 if the capability is granted for @tsk.
 * @quotactl:
 *      Check whether the quotactl syscall is allowed for this @sb.
 * @quota_on:
 *      Check whether QUOTAON is allowed for this @dentry.
 * @syslog:
 *      Check permission before accessing the kernel message ring or changing
 *      logging to the console.
 *      See the syslog(2) manual page for an explanation of the @type values.
 *      @type contains the SYSLOG_ACTION_* constant from <include/linux/syslog.h>
 *      Return 0 if permission is granted.
 * @settime:
 *      Check permission to change the system time.
 *      struct timespec64 is defined in <include/linux/time64.h> and timezone
 *      is defined in <include/linux/time.h>
 *      @ts contains new time
 *      @tz contains new timezone
 *      Return 0 if permission is granted.
 * @vm_enough_memory:
 *      Check permissions for allocating a new virtual mapping.
 *      @mm contains the mm struct it is being added to.
 *      @pages contains the number of pages.
 *      Return 0 if permission is granted.
 *
 * @ismaclabel:
 *      Check if the extended attribute specified by @name
 *      represents a MAC label. Returns 1 if name is a MAC
 *      attribute otherwise returns 0.
 *      @name full extended attribute name to check against
 *      LSM as a MAC label.
 *
 * @secid_to_secctx:
 *      Convert secid to security context.  If secdata is NULL the length of
 *      the result will be returned in seclen, but no secdata will be returned.
 *      This does mean that the length could change between calls to check the
 *      length and the next call which actually allocates and returns the
 *      secdata.
 *      @secid contains the security ID.
 *      @secdata contains the pointer that stores the converted security
 *      context.
 *      @seclen pointer which contains the length of the data
 * @secctx_to_secid:
 *      Convert security context to secid.
 *      @secid contains the pointer to the generated security ID.
 *      @secdata contains the security context.
 *
 * @release_secctx:
 *      Release the security context.
 *      @secdata contains the security context.
 *      @seclen contains the length of the security context.
 *
 * Security hooks for Audit
 *
 * @audit_rule_init:
 *      Allocate and initialize an LSM audit rule structure.
 *      @field contains the required Audit action.
 *      Fields flags are defined in <include/linux/audit.h>
 *      @op contains the operator the rule uses.
 *      @rulestr contains the context where the rule will be applied to.
 *      @lsmrule contains a pointer to receive the result.
 *      Return 0 if @lsmrule has been successfully set,
 *      -EINVAL in case of an invalid rule.
 *
 * @audit_rule_known:
 *      Specifies whether given @krule contains any fields related to
 *      current LSM.
 *      @krule contains the audit rule of interest.
 *      Return 1 in case of relation found, 0 otherwise.
 *
 * @audit_rule_match:
 *      Determine if given @secid matches a rule previously approved
 *      by @audit_rule_known.
 *      @secid contains the security id in question.
 *      @field contains the field which relates to current LSM.
 *      @op contains the operator that will be used for matching.
 *      @lrule points to the audit rule that will be checked against.
 *      Return 1 if secid matches the rule, 0 if it does not, -ERRNO on failure.
 *
 * @audit_rule_free:
 *      Deallocate the LSM audit rule structure previously allocated by
 *      audit_rule_init.
 *      @lsmrule contains the allocated rule
 *
 * @inode_invalidate_secctx:
 *      Notify the security module that it must revalidate the security context
 *      of an inode.
 *
 * @inode_notifysecctx:
 *      Notify the security module of what the security context of an inode
 *      should be.  Initializes the incore security context managed by the
 *      security module for this inode.  Example usage:  NFS client invokes
 *      this hook to initialize the security context in its incore inode to the
 *      value provided by the server for the file when the server returned the
 *      file's attributes to the client.
 *      Must be called with inode->i_mutex locked.
 *      @inode we wish to set the security context of.
 *      @ctx contains the string which we wish to set in the inode.
 *      @ctxlen contains the length of @ctx.
 *
 * @inode_setsecctx:
 *      Change the security context of an inode.  Updates the
 *      incore security context managed by the security module and invokes the
 *      fs code as needed (via __vfs_setxattr_noperm) to update any backing
 *      xattrs that represent the context.  Example usage:  NFS server invokes
 *      this hook to change the security context in its incore inode and on the
 *      backing filesystem to a value provided by the client on a SETATTR
 *      operation.
 *      Must be called with inode->i_mutex locked.
 *      @dentry contains the inode we wish to set the security context of.
 *      @ctx contains the string which we wish to set in the inode.
 *      @ctxlen contains the length of @ctx.
 *
 * @inode_getsecctx:
 *      On success, returns 0 and fills out @ctx and @ctxlen with the security
 *      context for the given @inode.
 *      @inode we wish to get the security context of.
 *      @ctx is a pointer in which to place the allocated security context.
 *      @ctxlen points to the place to put the length of @ctx.
 *
 * Security hooks for the general notification queue:
 *
 * @post_notification:
 *      Check to see if a watch notification can be posted to a particular
 *      queue.
 *      @w_cred: The credentials of the whoever set the watch.
 *      @cred: The event-triggerer's credentials
 *      @n: The notification being posted
 *
 * @watch_key:
 *      Check to see if a process is allowed to watch for event notifications
 *      from a key or keyring.
 *      @key: The key to watch.
 *
 * Security hooks for using the eBPF maps and programs functionalities through
 * eBPF syscalls.
 *
 * @bpf:
 *      Do a initial check for all bpf syscalls after the attribute is copied
 *      into the kernel. The actual security module can implement their own
 *      rules to check the specific cmd they need.
 *
 * @bpf_map:
 *      Do a check when the kernel generate and return a file descriptor for
 *      eBPF maps.
 *
 *      @map: bpf map that we want to access
 *      @mask: the access flags
 *
 * @bpf_prog:
 *      Do a check when the kernel generate and return a file descriptor for
 *      eBPF programs.
 *
 *      @prog: bpf prog that userspace want to use.
 *
 * @bpf_map_alloc_security:
 *      Initialize the security field inside bpf map.
 *
 * @bpf_map_free_security:
 *      Clean up the security information stored inside bpf map.
 *
 * @bpf_prog_alloc_security:
 *      Initialize the security field inside bpf program.
 *
 * @bpf_prog_free_security:
 *      Clean up the security information stored inside bpf prog.
 *
 * @locked_down:
 *     Determine whether a kernel feature that potentially enables arbitrary
 *     code execution in kernel space should be permitted.
 *
 *     @what: kernel feature being accessed
 *
 * Security hooks for perf events
 *
 * @perf_event_open:
 *      Check whether the @type of perf_event_open syscall is allowed.
 * @perf_event_alloc:
 *      Allocate and save perf_event security info.
 * @perf_event_free:
 *      Release (free) perf_event security info.
 * @perf_event_read:
 *      Read perf_event security info if allowed.
 * @perf_event_write:
 *      Write perf_event security info if allowed.
 */
union security_list_options {
        #define LSM_HOOK(RET, DEFAULT, NAME, ...) RET (*NAME)(__VA_ARGS__);
        #include "lsm_hook_defs.h"
        #undef LSM_HOOK
};

struct security_hook_heads {
        #define LSM_HOOK(RET, DEFAULT, NAME, ...) struct hlist_head NAME;
        #include "lsm_hook_defs.h"
        #undef LSM_HOOK
} __randomize_layout;

/*
 * Security module hook list structure.
 * For use with generic list macros for common operations.
 */
struct security_hook_list {
        struct hlist_node               list;
        struct hlist_head               *head;
        union security_list_options     hook;
        char                            *lsm;
} __randomize_layout;

/*
 * Security blob size or offset data.
 */
struct lsm_blob_sizes {
        int     lbs_cred;
        int     lbs_file;
        int     lbs_inode;
        int     lbs_superblock;
        int     lbs_ipc;
        int     lbs_msg_msg;
        int     lbs_task;
};

/*
 * LSM_RET_VOID is used as the default value in LSM_HOOK definitions for void
 * LSM hooks (in include/linux/lsm_hook_defs.h).
 */
#define LSM_RET_VOID ((void) 0)

/*
 * Initializing a security_hook_list structure takes
 * up a lot of space in a source file. This macro takes
 * care of the common case and reduces the amount of
 * text involved.
 */
#define LSM_HOOK_INIT(HEAD, HOOK) \
        { .head = &security_hook_heads.HEAD, .hook = { .HEAD = HOOK } }

extern struct security_hook_heads security_hook_heads;
extern char *lsm_names;

extern void security_add_hooks(struct security_hook_list *hooks, int count,
                                char *lsm);

#define LSM_FLAG_LEGACY_MAJOR   BIT(0)
#define LSM_FLAG_EXCLUSIVE      BIT(1)

enum lsm_order {
        LSM_ORDER_FIRST = -1,   /* This is only for capabilities. */
        LSM_ORDER_MUTABLE = 0,
};

struct lsm_info {
        const char *name;       /* Required. */
        enum lsm_order order;   /* Optional: default is LSM_ORDER_MUTABLE */
        unsigned long flags;    /* Optional: flags describing LSM */
        int *enabled;           /* Optional: controlled by CONFIG_LSM */
        int (*init)(void);      /* Required. */
        struct lsm_blob_sizes *blobs; /* Optional: for blob sharing. */
};

extern struct lsm_info __start_lsm_info[], __end_lsm_info[];
extern struct lsm_info __start_early_lsm_info[], __end_early_lsm_info[];

#define DEFINE_LSM(lsm)                                                 \
        static struct lsm_info __lsm_##lsm                              \
                __used __section(".lsm_info.init")                      \
                __aligned(sizeof(unsigned long))

#define DEFINE_EARLY_LSM(lsm)                                           \
        static struct lsm_info __early_lsm_##lsm                        \
                __used __section(".early_lsm_info.init")                \
                __aligned(sizeof(unsigned long))

#ifdef CONFIG_SECURITY_SELINUX_DISABLE
/*
 * Assuring the safety of deleting a security module is up to
 * the security module involved. This may entail ordering the
 * module's hook list in a particular way, refusing to disable
 * the module once a policy is loaded or any number of other
 * actions better imagined than described.
 *
 * The name of the configuration option reflects the only module
 * that currently uses the mechanism. Any developer who thinks
 * disabling their module is a good idea needs to be at least as
 * careful as the SELinux team.
 */
static inline void security_delete_hooks(struct security_hook_list *hooks,
                                                int count)
{
        int i;

        for (i = 0; i < count; i++)
                hlist_del_rcu(&hooks[i].list);
}
#endif /* CONFIG_SECURITY_SELINUX_DISABLE */

/* Currently required to handle SELinux runtime hook disable. */
#ifdef CONFIG_SECURITY_WRITABLE_HOOKS
#define __lsm_ro_after_init
#else
#define __lsm_ro_after_init     __ro_after_init
#endif /* CONFIG_SECURITY_WRITABLE_HOOKS */

extern int lsm_inode_alloc(struct inode *inode);

#endif /* ! __LINUX_LSM_HOOKS_H */