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>

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index d479def..24a00d9 100644 (file)
--- 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