apparmor: refactor path name lookup and permission checks around labels

[mirror_ubuntu-bionic-kernel.git] / security / apparmor / include / file.h

/*
 * AppArmor security module
 *
 * This file contains AppArmor file mediation function definitions.
 *
 * Copyright (C) 1998-2008 Novell/SUSE
 * Copyright 2009-2010 Canonical Ltd.
 *
 * 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, version 2 of the
 * License.
 */

#ifndef __AA_FILE_H
#define __AA_FILE_H

#include <linux/spinlock.h>

#include "domain.h"
#include "match.h"
#include "perms.h"

struct aa_profile;
struct path;

#define mask_mode_t(X) (X & (MAY_EXEC | MAY_WRITE | MAY_READ | MAY_APPEND))

#define AA_AUDIT_FILE_MASK	(MAY_READ | MAY_WRITE | MAY_EXEC | MAY_APPEND |\
				 AA_MAY_CREATE | AA_MAY_DELETE |	\
				 AA_MAY_GETATTR | AA_MAY_SETATTR | \
				 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_LOCK | \
				 AA_EXEC_MMAP | AA_MAY_LINK)

#define file_ctx(X) ((struct aa_file_ctx *)(X)->f_security)

/* struct aa_file_ctx - the AppArmor context the file was opened in
 * @lock: lock to update the ctx
 * @label: label currently cached on the ctx
 * @perms: the permission the file was opened with
 */
struct aa_file_ctx {
	spinlock_t lock;
	struct aa_label __rcu *label;
	u32 allow;
};

/**
 * aa_alloc_file_ctx - allocate file_ctx
 * @label: initial label of task creating the file
 * @gfp: gfp flags for allocation
 *
 * Returns: file_ctx or NULL on failure
 */
static inline struct aa_file_ctx *aa_alloc_file_ctx(struct aa_label *label,
						    gfp_t gfp)
{
	struct aa_file_ctx *ctx;

	ctx = kzalloc(sizeof(struct aa_file_ctx), gfp);
	if (ctx) {
		spin_lock_init(&ctx->lock);
		rcu_assign_pointer(ctx->label, aa_get_label(label));
	}
	return ctx;
}

/**
 * aa_free_file_ctx - free a file_ctx
 * @ctx: file_ctx to free  (MAYBE_NULL)
 */
static inline void aa_free_file_ctx(struct aa_file_ctx *ctx)
{
	if (ctx) {
		aa_put_label(rcu_access_pointer(ctx->label));
		kzfree(ctx);
	}
}

static inline struct aa_label *aa_get_file_label(struct aa_file_ctx *ctx)
{
	return aa_get_label_rcu(&ctx->label);
}

/*
 * The xindex is broken into 3 parts
 * - index - an index into either the exec name table or the variable table
 * - exec type - which determines how the executable name and index are used
 * - flags - which modify how the destination name is applied
 */
#define AA_X_INDEX_MASK		0x03ff

#define AA_X_TYPE_MASK		0x0c00
#define AA_X_TYPE_SHIFT		10
#define AA_X_NONE		0x0000
#define AA_X_NAME		0x0400	/* use executable name px */
#define AA_X_TABLE		0x0800	/* use a specified name ->n# */

#define AA_X_UNSAFE		0x1000
#define AA_X_CHILD		0x2000	/* make >AA_X_NONE apply to children */
#define AA_X_INHERIT		0x4000
#define AA_X_UNCONFINED		0x8000

/* AA_SECURE_X_NEEDED - is passed in the bprm->unsafe field */
#define AA_SECURE_X_NEEDED	0x8000

/* need to make conditional which ones are being set */
struct path_cond {
	kuid_t uid;
	umode_t mode;
};

#define COMBINED_PERM_MASK(X) ((X).allow | (X).audit | (X).quiet | (X).kill)

/* FIXME: split perms from dfa and match this to description
 *        also add delegation info.
 */
static inline u16 dfa_map_xindex(u16 mask)
{
	u16 old_index = (mask >> 10) & 0xf;
	u16 index = 0;

	if (mask & 0x100)
		index |= AA_X_UNSAFE;
	if (mask & 0x200)
		index |= AA_X_INHERIT;
	if (mask & 0x80)
		index |= AA_X_UNCONFINED;

	if (old_index == 1) {
		index |= AA_X_UNCONFINED;
	} else if (old_index == 2) {
		index |= AA_X_NAME;
	} else if (old_index == 3) {
		index |= AA_X_NAME | AA_X_CHILD;
	} else if (old_index) {
		index |= AA_X_TABLE;
		index |= old_index - 4;
	}

	return index;
}

/*
 * map old dfa inline permissions to new format
 */
#define dfa_user_allow(dfa, state) (((ACCEPT_TABLE(dfa)[state]) & 0x7f) | \
				    ((ACCEPT_TABLE(dfa)[state]) & 0x80000000))
#define dfa_user_audit(dfa, state) ((ACCEPT_TABLE2(dfa)[state]) & 0x7f)
#define dfa_user_quiet(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 7) & 0x7f)
#define dfa_user_xindex(dfa, state) \
	(dfa_map_xindex(ACCEPT_TABLE(dfa)[state] & 0x3fff))

#define dfa_other_allow(dfa, state) ((((ACCEPT_TABLE(dfa)[state]) >> 14) & \
				      0x7f) |				\
				     ((ACCEPT_TABLE(dfa)[state]) & 0x80000000))
#define dfa_other_audit(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 14) & 0x7f)
#define dfa_other_quiet(dfa, state) \
	((((ACCEPT_TABLE2(dfa)[state]) >> 7) >> 14) & 0x7f)
#define dfa_other_xindex(dfa, state) \
	dfa_map_xindex((ACCEPT_TABLE(dfa)[state] >> 14) & 0x3fff)

int aa_audit_file(struct aa_profile *profile, struct aa_perms *perms,
		  const char *op, u32 request, const char *name,
		  const char *target, struct aa_label *tlabel, kuid_t ouid,
		  const char *info, int error);

/**
 * struct aa_file_rules - components used for file rule permissions
 * @dfa: dfa to match path names and conditionals against
 * @perms: permission table indexed by the matched state accept entry of @dfa
 * @trans: transition table for indexed by named x transitions
 *
 * File permission are determined by matching a path against @dfa and then
 * then using the value of the accept entry for the matching state as
 * an index into @perms.  If a named exec transition is required it is
 * looked up in the transition table.
 */
struct aa_file_rules {
	unsigned int start;
	struct aa_dfa *dfa;
	/* struct perms perms; */
	struct aa_domain trans;
	/* TODO: add delegate table */
};

struct aa_perms aa_compute_fperms(struct aa_dfa *dfa, unsigned int state,
				    struct path_cond *cond);
unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
			  const char *name, struct path_cond *cond,
			  struct aa_perms *perms);

int __aa_path_perm(const char *op, struct aa_profile *profile,
		   const char *name, u32 request, struct path_cond *cond,
		   int flags, struct aa_perms *perms);
int aa_path_perm(const char *op, struct aa_label *label,
		 const struct path *path, int flags, u32 request,
		 struct path_cond *cond);

int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry,
		 const struct path *new_dir, struct dentry *new_dentry);

int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
		 u32 request);

void aa_inherit_files(const struct cred *cred, struct files_struct *files);

static inline void aa_free_file_rules(struct aa_file_rules *rules)
{
	aa_put_dfa(rules->dfa);
	aa_free_domain_entries(&rules->trans);
}

/**
 * aa_map_file_perms - map file flags to AppArmor permissions
 * @file: open file to map flags to AppArmor permissions
 *
 * Returns: apparmor permission set for the file
 */
static inline u32 aa_map_file_to_perms(struct file *file)
{
	int flags = file->f_flags;
	u32 perms = 0;

	if (file->f_mode & FMODE_WRITE)
		perms |= MAY_WRITE;
	if (file->f_mode & FMODE_READ)
		perms |= MAY_READ;

	if ((flags & O_APPEND) && (perms & MAY_WRITE))
		perms = (perms & ~MAY_WRITE) | MAY_APPEND;
	/* trunc implies write permission */
	if (flags & O_TRUNC)
		perms |= MAY_WRITE;
	if (flags & O_CREAT)
		perms |= AA_MAY_CREATE;

	return perms;
}

#endif /* __AA_FILE_H */