smack: rewrite smack_sb_eat_lsm_opts()

make it use smack_add_opt() and avoid separate copies - gather
non-LSM options by memmove() in place

Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 23 insertions, 85 deletions

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index d479def4d6a0..24a00d93d8c3 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -599,53 +599,6 @@ static void smack_free_mnt_opts(void *mnt_opts)
         kfree(opts);
 }
 
-/**
- * smack_sb_copy_data - copy mount options data for processing
- * @orig: where to start
- * @smackopts: mount options string
- *
- * Returns 0 on success or -ENOMEM on error.
- *
- * Copy the Smack specific mount options out of the mount
- * options list.
- */
-static int smack_sb_copy_data(char *orig, char *smackopts)
-{
-        char *cp, *commap, *otheropts, *dp;
-
-        otheropts = (char *)get_zeroed_page(GFP_KERNEL);
-        if (otheropts == NULL)
-                return -ENOMEM;
-
-        for (cp = orig, commap = orig; commap != NULL; cp = commap + 1) {
-                if (strstr(cp, SMK_FSDEFAULT) == cp)
-                        dp = smackopts;
-                else if (strstr(cp, SMK_FSFLOOR) == cp)
-                        dp = smackopts;
-                else if (strstr(cp, SMK_FSHAT) == cp)
-                        dp = smackopts;
-                else if (strstr(cp, SMK_FSROOT) == cp)
-                        dp = smackopts;
-                else if (strstr(cp, SMK_FSTRANS) == cp)
-                        dp = smackopts;
-                else
-                        dp = otheropts;
-
-                commap = strchr(cp, ',');
-                if (commap != NULL)
-                        *commap = '\0';
-
-                if (*dp != '\0')
-                        strcat(dp, ",");
-                strcat(dp, cp);
-        }
-
-        strcpy(orig, otheropts);
-        free_page((unsigned long)otheropts);
-
-        return 0;
-}
-
 static int smack_add_opt(int token, const char *s, void **mnt_opts)
 {
         struct smack_mnt_opts *opts = *mnt_opts;
@@ -656,7 +609,6 @@ static int smack_add_opt(int token, const char *s, void **mnt_opts)
                         return -ENOMEM;
                 *mnt_opts = opts;
         }
-
         if (!s)
                 return -ENOMEM;
 
@@ -694,22 +646,10 @@ out_opt_err:
         return -EINVAL;
 }
 
-/**
- * smack_parse_opts_str - parse Smack specific mount options
- * @options: mount options string
- * @opts: where to store converted mount opts
- *
- * Returns 0 on success or -ENOMEM on error.
- *
- * converts Smack specific mount options to generic security option format
- */
-static int smack_parse_opts_str(char *options,
-                void **mnt_opts)
+static int smack_sb_eat_lsm_opts(char *options, void **mnt_opts)
 {
-        char *from = options;
-
-        if (!options)
-                return 0;
+        char *from = options, *to = options;
+        bool first = true;
 
         while (1) {
                 char *next = strchr(from, ',');
@@ -722,36 +662,34 @@ static int smack_parse_opts_str(char *options,
                         len = strlen(from);
 
                 token = match_opt_prefix(from, len, &arg);
-                arg = kmemdup_nul(arg, from + len - arg, GFP_KERNEL);
-                rc = smack_add_opt(token, arg, mnt_opts);
-                if (unlikely(rc)) {
-                        kfree(arg);
-                        if (*mnt_opts)
-                                smack_free_mnt_opts(*mnt_opts);
-                        *mnt_opts = NULL;
-                        return rc;
+                if (token != Opt_error) {
+                        arg = kmemdup_nul(arg, from + len - arg, GFP_KERNEL);
+                        rc = smack_add_opt(token, arg, mnt_opts);
+                        if (unlikely(rc)) {
+                                kfree(arg);
+                                if (*mnt_opts)
+                                        smack_free_mnt_opts(*mnt_opts);
+                                *mnt_opts = NULL;
+                                return rc;
+                        }
+                } else {
+                        if (!first) {   // copy with preceding comma
+                                from--;
+                                len++;
+                        }
+                        if (to != from)
+                                memmove(to, from, len);
+                        to += len;
+                        first = false;
                 }
                 if (!from[len])
                         break;
                 from += len + 1;
         }
+        *to = '\0';
         return 0;
 }
 
-static int smack_sb_eat_lsm_opts(char *options, void **mnt_opts)
-{
-        char *s = (char *)get_zeroed_page(GFP_KERNEL);
-        int err;
-
-        if (!s)
-                return -ENOMEM;
-        err = smack_sb_copy_data(options, s);
-        if (!err)
-                err = smack_parse_opts_str(s, mnt_opts);
-        free_page((unsigned long)s);
-        return err;
-}
-
 /**
  * smack_set_mnt_opts - set Smack specific mount options
  * @sb: the file system superblock