1 files changed, 57 insertions, 9 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 7e101dbea4cb..2e8b4dfcbc74 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -320,12 +320,14 @@ enum {
         Opt_context = 1,
         Opt_fscontext = 2,
         Opt_defcontext = 4,
+        Opt_rootcontext = 8,
 };
 
 static match_table_t tokens = {
         {Opt_context, "context=%s"},
         {Opt_fscontext, "fscontext=%s"},
         {Opt_defcontext, "defcontext=%s"},
+        {Opt_rootcontext, "rootcontext=%s"},
 };
 
 #define SEL_MOUNT_FAIL_MSG "SELinux:  duplicate or incompatible mount options\n"
@@ -346,10 +348,25 @@ static int may_context_mount_sb_relabel(u32 sid,
         return rc;
 }
 
+static int may_context_mount_inode_relabel(u32 sid,
+                        struct superblock_security_struct *sbsec,
+                        struct task_security_struct *tsec)
+{
+        int rc;
+        rc = avc_has_perm(tsec->sid, sbsec->sid, SECCLASS_FILESYSTEM,
+                          FILESYSTEM__RELABELFROM, NULL);
+        if (rc)
+                return rc;
+
+        rc = avc_has_perm(sid, sbsec->sid, SECCLASS_FILESYSTEM,
+                          FILESYSTEM__ASSOCIATE, NULL);
+        return rc;
+}
+
 static int try_context_mount(struct super_block *sb, void *data)
 {
         char *context = NULL, *defcontext = NULL;
-        char *fscontext = NULL;
+        char *fscontext = NULL, *rootcontext = NULL;
         const char *name;
         u32 sid;
         int alloc = 0, rc = 0, seen = 0;
@@ -423,6 +440,22 @@ static int try_context_mount(struct super_block *sb, void *data)
                                 seen |= Opt_fscontext;
                                 break;
 
+                        case Opt_rootcontext:
+                                if (seen & Opt_rootcontext) {
+                                        rc = -EINVAL;
+                                        printk(KERN_WARNING SEL_MOUNT_FAIL_MSG);
+                                        goto out_free;
+                                }
+                                rootcontext = match_strdup(&args[0]);
+                                if (!rootcontext) {
+                                        rc = -ENOMEM;
+                                        goto out_free;
+                                }
+                                if (!alloc)
+                                        alloc = 1;
+                                seen |= Opt_rootcontext;
+                                break;
+
                         case Opt_defcontext:
                                 if (sbsec->behavior != SECURITY_FS_USE_XATTR) {
                                         rc = -EINVAL;
@@ -501,6 +534,25 @@ static int try_context_mount(struct super_block *sb, void *data)
                 sbsec->behavior = SECURITY_FS_USE_MNTPOINT;
         }
 
+        if (rootcontext) {
+                struct inode *inode = sb->s_root->d_inode;
+                struct inode_security_struct *isec = inode->i_security;
+                rc = security_context_to_sid(rootcontext, strlen(rootcontext), &sid);
+                if (rc) {
+                        printk(KERN_WARNING "SELinux: security_context_to_sid"
+                               "(%s) failed for (dev %s, type %s) errno=%d\n",
+                               rootcontext, sb->s_id, name, rc);
+                        goto out_free;
+                }
+
+                rc = may_context_mount_inode_relabel(sid, sbsec, tsec);
+                if (rc)
+                        goto out_free;
+
+                isec->sid = sid;
+                isec->initialized = 1;
+        }
+
         if (defcontext) {
                 rc = security_context_to_sid(defcontext, strlen(defcontext), &sid);
                 if (rc) {
@@ -513,13 +565,7 @@ static int try_context_mount(struct super_block *sb, void *data)
                 if (sid == sbsec->def_sid)
                         goto out_free;
 
-                rc = avc_has_perm(tsec->sid, sbsec->sid, SECCLASS_FILESYSTEM,
-                                  FILESYSTEM__RELABELFROM, NULL);
-                if (rc)
-                        goto out_free;
-
-                rc = avc_has_perm(sid, sbsec->sid, SECCLASS_FILESYSTEM,
-                                  FILESYSTEM__ASSOCIATE, NULL);
+                rc = may_context_mount_inode_relabel(sid, sbsec, tsec);
                 if (rc)
                         goto out_free;
 
@@ -531,6 +577,7 @@ out_free:
                 kfree(context);
                 kfree(defcontext);
                 kfree(fscontext);
+                kfree(rootcontext);
         }
 out:
         return rc;
@@ -1882,7 +1929,8 @@ static inline int selinux_option(char *option, int len)
 {
         return (match_prefix("context=", sizeof("context=")-1, option, len) ||
                 match_prefix("fscontext=", sizeof("fscontext=")-1, option, len) ||
-                match_prefix("defcontext=", sizeof("defcontext=")-1, option, len));
+                match_prefix("defcontext=", sizeof("defcontext=")-1, option, len) ||
+                match_prefix("rootcontext=", sizeof("rootcontext=")-1, option, len));
 }
 
 static inline void take_option(char **to, char *from, int *first, int len)