lsm,selinux: add new hook to compare new mount to an existing mount

[sfrench/cifs-2.6.git] / security / selinux / hooks.c

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index eca9fc0ba764607b596fb73247c60c7525a284a2..07ca2ebf979eccfcc0585169c6d53f18ffc94d2c 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2685,6 +2685,61 @@ free_opt:
        return rc;
 }
 
+static int selinux_sb_mnt_opts_compat(struct super_block *sb, void *mnt_opts)
+{
+       struct selinux_mnt_opts *opts = mnt_opts;
+       struct superblock_security_struct *sbsec = sb->s_security;
+       u32 sid;
+       int rc;
+
+       /*
+        * Superblock not initialized (i.e. no options) - reject if any
+        * options specified, otherwise accept.
+        */
+       if (!(sbsec->flags & SE_SBINITIALIZED))
+               return opts ? 1 : 0;
+
+       /*
+        * Superblock initialized and no options specified - reject if
+        * superblock has any options set, otherwise accept.
+        */
+       if (!opts)
+               return (sbsec->flags & SE_MNTMASK) ? 1 : 0;
+
+       if (opts->fscontext) {
+               rc = parse_sid(sb, opts->fscontext, &sid);
+               if (rc)
+                       return 1;
+               if (bad_option(sbsec, FSCONTEXT_MNT, sbsec->sid, sid))
+                       return 1;
+       }
+       if (opts->context) {
+               rc = parse_sid(sb, opts->context, &sid);
+               if (rc)
+                       return 1;
+               if (bad_option(sbsec, CONTEXT_MNT, sbsec->mntpoint_sid, sid))
+                       return 1;
+       }
+       if (opts->rootcontext) {
+               struct inode_security_struct *root_isec;
+
+               root_isec = backing_inode_security(sb->s_root);
+               rc = parse_sid(sb, opts->rootcontext, &sid);
+               if (rc)
+                       return 1;
+               if (bad_option(sbsec, ROOTCONTEXT_MNT, root_isec->sid, sid))
+                       return 1;
+       }
+       if (opts->defcontext) {
+               rc = parse_sid(sb, opts->defcontext, &sid);
+               if (rc)
+                       return 1;
+               if (bad_option(sbsec, DEFCONTEXT_MNT, sbsec->def_sid, sid))
+                       return 1;
+       }
+       return 0;
+}
+
 static int selinux_sb_remount(struct super_block *sb, void *mnt_opts)
 {
        struct selinux_mnt_opts *opts = mnt_opts;
@@ -7078,6 +7133,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 
        LSM_HOOK_INIT(sb_free_security, selinux_sb_free_security),
        LSM_HOOK_INIT(sb_free_mnt_opts, selinux_free_mnt_opts),
+       LSM_HOOK_INIT(sb_mnt_opts_compat, selinux_sb_mnt_opts_compat),
        LSM_HOOK_INIT(sb_remount, selinux_sb_remount),
        LSM_HOOK_INIT(sb_kern_mount, selinux_sb_kern_mount),
        LSM_HOOK_INIT(sb_show_options, selinux_sb_show_options),