selinux: rewrite selinux_sb_eat_lsm_opts()

make it use selinux_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, 54 insertions, 92 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 9b350070ed9e..5336d6671c5c 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2606,109 +2606,71 @@ static void selinux_sb_free_security(struct super_block *sb)
         superblock_free_security(sb);
 }
 
-static inline int match_prefix(char *prefix, int plen, char *option, int olen)
+static inline int opt_len(const char *s)
 {
-        if (plen > olen)
-                return 0;
-
-        return !memcmp(prefix, option, plen);
-}
-
-static inline int selinux_option(char *option, int len)
-{
-        return (match_prefix(CONTEXT_STR, sizeof(CONTEXT_STR)-1, option, len) ||
-                match_prefix(FSCONTEXT_STR, sizeof(FSCONTEXT_STR)-1, option, len) ||
-                match_prefix(DEFCONTEXT_STR, sizeof(DEFCONTEXT_STR)-1, option, len) ||
-                match_prefix(ROOTCONTEXT_STR, sizeof(ROOTCONTEXT_STR)-1, option, len) ||
-                match_prefix(LABELSUPP_STR, sizeof(LABELSUPP_STR)-1, option, len));
-}
-
-static inline void take_option(char **to, char *from, int *first, int len)
-{
-        if (!*first) {
-                **to = ',';
-                *to += 1;
-        } else
-                *first = 0;
-        memcpy(*to, from, len);
-        *to += len;
-}
-
-static inline void take_selinux_option(char **to, char *from, int *first,
-                                       int len)
-{
-        int current_size = 0;
-
-        if (!*first) {
-                **to = '|';
-                *to += 1;
-        } else
-                *first = 0;
+        bool open_quote = false;
+        int len;
+        char c;
 
-        while (current_size < len) {
-                if (*from != '"') {
-                        **to = *from;
-                        *to += 1;
-                }
-                from += 1;
-                current_size += 1;
+        for (len = 0; (c = s[len]) != '\0'; len++) {
+                if (c == '"')
+                        open_quote = !open_quote;
+                if (c == ',' && !open_quote)
+                        break;
         }
+        return len;
 }
 
-static int selinux_sb_copy_data(char *orig, char *copy)
+static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts)
 {
-        int fnosec, fsec, rc = 0;
-        char *in_save, *in_curr, *in_end;
-        char *sec_curr, *nosec_save, *nosec;
-        int open_quote = 0;
+        char *from = options;
+        char *to = options;
+        bool first = true;
 
-        in_curr = orig;
-        sec_curr = copy;
+        while (1) {
+                int len = opt_len(from);
+                int token, rc;
+                char *arg = NULL;
 
-        nosec = (char *)get_zeroed_page(GFP_KERNEL);
-        if (!nosec) {
-                rc = -ENOMEM;
-                goto out;
-        }
+                token = match_opt_prefix(from, len, &arg);
 
-        nosec_save = nosec;
-        fnosec = fsec = 1;
-        in_save = in_end = orig;
+                if (token != Opt_error) {
+                        char *p, *q;
 
-        do {
-                if (*in_end == '"')
-                        open_quote = !open_quote;
-                if ((*in_end == ',' && open_quote == 0) ||
-                                *in_end == '\0') {
-                        int len = in_end - in_curr;
-
-                        if (selinux_option(in_curr, len))
-                                take_selinux_option(&sec_curr, in_curr, &fsec, len);
-                        else
-                                take_option(&nosec, in_curr, &fnosec, len);
-
-                        in_curr = in_end + 1;
+                        /* strip quotes */
+                        if (arg) {
+                                for (p = q = arg; p < from + len; p++) {
+                                        char c = *p;
+                                        if (c != '"')
+                                                *q++ = c;
+                                }
+                                arg = kmemdup_nul(arg, q - arg, GFP_KERNEL);
+                        }
+                        rc = selinux_add_opt(token, arg, mnt_opts);
+                        if (unlikely(rc)) {
+                                kfree(arg);
+                                if (*mnt_opts) {
+                                        selinux_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;
                 }
-        } while (*in_end++);
-
-        strcpy(in_save, nosec_save);
-        free_page((unsigned long)nosec_save);
-out:
-        return rc;
-}
-
-static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts)
-{
-        char *s = (char *)get_zeroed_page(GFP_KERNEL);
-        int err;
-
-        if (!s)
-                return -ENOMEM;
-        err = selinux_sb_copy_data(options, s);
-        if (!err)
-                err = selinux_parse_opts_str(s, mnt_opts);
-        free_page((unsigned long)s);
-        return err;
+                if (!from[len])
+                        break;
+                from += len + 1;
+        }
+        *to = '\0';
+        return 0;
 }
 
 static int selinux_sb_remount(struct super_block *sb, void *mnt_opts)