selinux: consider filesystem subtype in policies
authorAnand Avati <avati@redhat.com>
Tue, 16 Apr 2013 22:56:19 +0000 (18:56 -0400)
committerEric Paris <eparis@redhat.com>
Wed, 28 Aug 2013 18:44:52 +0000 (14:44 -0400)
Not considering sub filesystem has the following limitation. Support
for SELinux in FUSE is dependent on the particular userspace
filesystem, which is identified by the subtype. For e.g, GlusterFS,
a FUSE based filesystem supports SELinux (by mounting and processing
FUSE requests in different threads, avoiding the mount time
deadlock), whereas other FUSE based filesystems (identified by a
different subtype) have the mount time deadlock.

By considering the subtype of the filesytem in the SELinux policies,
allows us to specify a filesystem subtype, in the following way:

fs_use_xattr fuse.glusterfs gen_context(system_u:object_r:fs_t,s0);

This way not all FUSE filesystems are put in the same bucket and
subjected to the limitations of the other subtypes.

Signed-off-by: Anand Avati <avati@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
security/selinux/hooks.c
security/selinux/ss/services.c

index 4fbf2c5f26ce5f3abccf283b108d62f6bdc778a8..0d4408debb457e684b44fb54f41d1eb60d879004 100644 (file)
 #include "audit.h"
 #include "avc_ss.h"
 
+#define SB_TYPE_FMT "%s%s%s"
+#define SB_SUBTYPE(sb) (sb->s_subtype && sb->s_subtype[0])
+#define SB_TYPE_ARGS(sb) sb->s_type->name, SB_SUBTYPE(sb) ? "." : "", SB_SUBTYPE(sb) ? sb->s_subtype : ""
+
 extern struct security_operations *security_ops;
 
 /* SECMARK reference count */
@@ -407,8 +411,8 @@ static int sb_finish_set_opts(struct super_block *sb)
                   the first boot of the SELinux kernel before we have
                   assigned xattr values to the filesystem. */
                if (!root_inode->i_op->getxattr) {
-                       printk(KERN_WARNING "SELinux: (dev %s, type %s) has no "
-                              "xattr support\n", sb->s_id, sb->s_type->name);
+                       printk(KERN_WARNING "SELinux: (dev %s, type "SB_TYPE_FMT") has no "
+                              "xattr support\n", sb->s_id, SB_TYPE_ARGS(sb));
                        rc = -EOPNOTSUPP;
                        goto out;
                }
@@ -416,22 +420,22 @@ static int sb_finish_set_opts(struct super_block *sb)
                if (rc < 0 && rc != -ENODATA) {
                        if (rc == -EOPNOTSUPP)
                                printk(KERN_WARNING "SELinux: (dev %s, type "
-                                      "%s) has no security xattr handler\n",
-                                      sb->s_id, sb->s_type->name);
+                                      SB_TYPE_FMT") has no security xattr handler\n",
+                                      sb->s_id, SB_TYPE_ARGS(sb));
                        else
                                printk(KERN_WARNING "SELinux: (dev %s, type "
-                                      "%s) getxattr errno %d\n", sb->s_id,
-                                      sb->s_type->name, -rc);
+                                      SB_TYPE_FMT") getxattr errno %d\n", sb->s_id,
+                                      SB_TYPE_ARGS(sb), -rc);
                        goto out;
                }
        }
 
        if (sbsec->behavior > ARRAY_SIZE(labeling_behaviors))
-               printk(KERN_ERR "SELinux: initialized (dev %s, type %s), unknown behavior\n",
-                      sb->s_id, sb->s_type->name);
+               printk(KERN_ERR "SELinux: initialized (dev %s, type "SB_TYPE_FMT"), unknown behavior\n",
+                      sb->s_id, SB_TYPE_ARGS(sb));
        else
-               printk(KERN_DEBUG "SELinux: initialized (dev %s, type %s), %s\n",
-                      sb->s_id, sb->s_type->name,
+               printk(KERN_DEBUG "SELinux: initialized (dev %s, type "SB_TYPE_FMT"), %s\n",
+                      sb->s_id, SB_TYPE_ARGS(sb),
                       labeling_behaviors[sbsec->behavior-1]);
 
        sbsec->flags |= SE_SBINITIALIZED;
@@ -589,7 +593,6 @@ static int selinux_set_mnt_opts(struct super_block *sb,
        const struct cred *cred = current_cred();
        int rc = 0, i;
        struct superblock_security_struct *sbsec = sb->s_security;
-       const char *name = sb->s_type->name;
        struct inode *inode = sbsec->sb->s_root->d_inode;
        struct inode_security_struct *root_isec = inode->i_security;
        u32 fscontext_sid = 0, context_sid = 0, rootcontext_sid = 0;
@@ -642,8 +645,8 @@ static int selinux_set_mnt_opts(struct super_block *sb,
                                             strlen(mount_options[i]), &sid);
                if (rc) {
                        printk(KERN_WARNING "SELinux: security_context_to_sid"
-                              "(%s) failed for (dev %s, type %s) errno=%d\n",
-                              mount_options[i], sb->s_id, name, rc);
+                              "(%s) failed for (dev %s, type "SB_TYPE_FMT") errno=%d\n",
+                              mount_options[i], sb->s_id, SB_TYPE_ARGS(sb), rc);
                        goto out;
                }
                switch (flags[i]) {
@@ -779,7 +782,8 @@ out:
 out_double_mount:
        rc = -EINVAL;
        printk(KERN_WARNING "SELinux: mount invalid.  Same superblock, different "
-              "security settings for (dev %s, type %s)\n", sb->s_id, name);
+              "security settings for (dev %s, type "SB_TYPE_FMT")\n", sb->s_id,
+              SB_TYPE_ARGS(sb));
        goto out;
 }
 
@@ -2439,8 +2443,8 @@ static int selinux_sb_remount(struct super_block *sb, void *data)
                rc = security_context_to_sid(mount_options[i], len, &sid);
                if (rc) {
                        printk(KERN_WARNING "SELinux: security_context_to_sid"
-                              "(%s) failed for (dev %s, type %s) errno=%d\n",
-                              mount_options[i], sb->s_id, sb->s_type->name, rc);
+                              "(%s) failed for (dev %s, type "SB_TYPE_FMT") errno=%d\n",
+                              mount_options[i], sb->s_id, SB_TYPE_ARGS(sb), rc);
                        goto out_free_opts;
                }
                rc = -EINVAL;
@@ -2478,8 +2482,8 @@ out_free_secdata:
        return rc;
 out_bad_option:
        printk(KERN_WARNING "SELinux: unable to change security options "
-              "during remount (dev %s, type=%s)\n", sb->s_id,
-              sb->s_type->name);
+              "during remount (dev %s, type "SB_TYPE_FMT")\n", sb->s_id,
+              SB_TYPE_ARGS(sb));
        goto out_free_opts;
 }
 
index d106733ad9878d6ee7543ff31c05a51f2c74b523..ee470a0b5c27fdad95a59b258792b6182435b999 100644 (file)
@@ -2334,16 +2334,50 @@ int security_fs_use(struct super_block *sb)
        struct ocontext *c;
        struct superblock_security_struct *sbsec = sb->s_security;
        const char *fstype = sb->s_type->name;
+       const char *subtype = (sb->s_subtype && sb->s_subtype[0]) ? sb->s_subtype : NULL;
+       struct ocontext *base = NULL;
 
        read_lock(&policy_rwlock);
 
-       c = policydb.ocontexts[OCON_FSUSE];
-       while (c) {
-               if (strcmp(fstype, c->u.name) == 0)
+       for (c = policydb.ocontexts[OCON_FSUSE]; c; c = c->next) {
+               char *sub;
+               int baselen;
+
+               baselen = strlen(fstype);
+
+               /* if base does not match, this is not the one */
+               if (strncmp(fstype, c->u.name, baselen))
+                       continue;
+
+               /* if there is no subtype, this is the one! */
+               if (!subtype)
+                       break;
+
+               /* skip past the base in this entry */
+               sub = c->u.name + baselen;
+
+               /* entry is only a base. save it. keep looking for subtype */
+               if (sub[0] == '\0') {
+                       base = c;
+                       continue;
+               }
+
+               /* entry is not followed by a subtype, so it is not a match */
+               if (sub[0] != '.')
+                       continue;
+
+               /* whew, we found a subtype of this fstype */
+               sub++; /* move past '.' */
+
+               /* exact match of fstype AND subtype */
+               if (!strcmp(subtype, sub))
                        break;
-               c = c->next;
        }
 
+       /* in case we had found an fstype match but no subtype match */
+       if (!c)
+               c = base;
+
        if (c) {
                sbsec->behavior = c->v.behavior;
                if (!c->sid[0]) {