Security: Add Hook to test if the particular xattr is part of a MAC model.

[mirror_ubuntu-bionic-kernel.git] / security / selinux / hooks.c

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index bf889ee51509654f1ac6550a54eec7cfa6be861d..bbf219a494d0eb7c031a37dc13a0412b27274a48 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -751,7 +751,37 @@ out_double_mount:
        goto out;
 }
 
-static void selinux_sb_clone_mnt_opts(const struct super_block *oldsb,
+static int selinux_cmp_sb_context(const struct super_block *oldsb,
+                                   const struct super_block *newsb)
+{
+       struct superblock_security_struct *old = oldsb->s_security;
+       struct superblock_security_struct *new = newsb->s_security;
+       char oldflags = old->flags & SE_MNTMASK;
+       char newflags = new->flags & SE_MNTMASK;
+
+       if (oldflags != newflags)
+               goto mismatch;
+       if ((oldflags & FSCONTEXT_MNT) && old->sid != new->sid)
+               goto mismatch;
+       if ((oldflags & CONTEXT_MNT) && old->mntpoint_sid != new->mntpoint_sid)
+               goto mismatch;
+       if ((oldflags & DEFCONTEXT_MNT) && old->def_sid != new->def_sid)
+               goto mismatch;
+       if (oldflags & ROOTCONTEXT_MNT) {
+               struct inode_security_struct *oldroot = oldsb->s_root->d_inode->i_security;
+               struct inode_security_struct *newroot = newsb->s_root->d_inode->i_security;
+               if (oldroot->sid != newroot->sid)
+                       goto mismatch;
+       }
+       return 0;
+mismatch:
+       printk(KERN_WARNING "SELinux: mount invalid.  Same superblock, "
+                           "different security settings for (dev %s, "
+                           "type %s)\n", newsb->s_id, newsb->s_type->name);
+       return -EBUSY;
+}
+
+static int selinux_sb_clone_mnt_opts(const struct super_block *oldsb,
                                        struct super_block *newsb)
 {
        const struct superblock_security_struct *oldsbsec = oldsb->s_security;
@@ -766,14 +796,14 @@ static void selinux_sb_clone_mnt_opts(const struct super_block *oldsb,
         * mount options.  thus we can safely deal with this superblock later
         */
        if (!ss_initialized)
-               return;
+               return 0;
 
        /* how can we clone if the old one wasn't set up?? */
        BUG_ON(!(oldsbsec->flags & SE_SBINITIALIZED));
 
-       /* if fs is reusing a sb, just let its options stand... */
+       /* if fs is reusing a sb, make sure that the contexts match */
        if (newsbsec->flags & SE_SBINITIALIZED)
-               return;
+               return selinux_cmp_sb_context(oldsb, newsb);
 
        mutex_lock(&newsbsec->lock);
 
@@ -806,6 +836,7 @@ static void selinux_sb_clone_mnt_opts(const struct super_block *oldsb,
 
        sb_finish_set_opts(newsb);
        mutex_unlock(&newsbsec->lock);
+       return 0;
 }
 
 static int selinux_parse_opts_str(char *options,
@@ -2484,6 +2515,40 @@ static void selinux_inode_free_security(struct inode *inode)
        inode_free_security(inode);
 }
 
+static int selinux_dentry_init_security(struct dentry *dentry, int mode,
+                                       struct qstr *name, void **ctx,
+                                       u32 *ctxlen)
+{
+       const struct cred *cred = current_cred();
+       struct task_security_struct *tsec;
+       struct inode_security_struct *dsec;
+       struct superblock_security_struct *sbsec;
+       struct inode *dir = dentry->d_parent->d_inode;
+       u32 newsid;
+       int rc;
+
+       tsec = cred->security;
+       dsec = dir->i_security;
+       sbsec = dir->i_sb->s_security;
+
+       if (tsec->create_sid && sbsec->behavior != SECURITY_FS_USE_MNTPOINT) {
+               newsid = tsec->create_sid;
+       } else {
+               rc = security_transition_sid(tsec->sid, dsec->sid,
+                                            inode_mode_to_security_class(mode),
+                                            name,
+                                            &newsid);
+               if (rc) {
+                       printk(KERN_WARNING
+                               "%s: security_transition_sid failed, rc=%d\n",
+                              __func__, -rc);
+                       return rc;
+               }
+       }
+
+       return security_sid_to_context(newsid, (char **)ctx, ctxlen);
+}
+
 static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
                                       const struct qstr *qstr, char **name,
                                       void **value, size_t *len)
@@ -5389,6 +5454,11 @@ abort_change:
        return error;
 }
 
+static int selinux_ismaclabel(const char *name)
+{
+       return (strcmp(name, XATTR_SELINUX_SUFFIX) == 0);
+}
+
 static int selinux_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
 {
        return security_sid_to_context(secid, secdata, seclen);
@@ -5531,6 +5601,7 @@ static struct security_operations selinux_ops = {
        .sb_clone_mnt_opts =            selinux_sb_clone_mnt_opts,
        .sb_parse_opts_str =            selinux_parse_opts_str,
 
+       .dentry_init_security =         selinux_dentry_init_security,
 
        .inode_alloc_security =         selinux_inode_alloc_security,
        .inode_free_security =          selinux_inode_free_security,
@@ -5626,6 +5697,7 @@ static struct security_operations selinux_ops = {
        .getprocattr =                  selinux_getprocattr,
        .setprocattr =                  selinux_setprocattr,
 
+       .ismaclabel =                   selinux_ismaclabel,
        .secid_to_secctx =              selinux_secid_to_secctx,
        .secctx_to_secid =              selinux_secctx_to_secid,
        .release_secctx =               selinux_release_secctx,