selinux: switch away from match_token()

It's not a good fit, unfortunately, and the next step will make it
even less so.  Open-code what we need here.

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

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 26ec7d6..8f2285c 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -459,19 +459,41 @@ enum {
        Opt_defcontext = 3,
        Opt_rootcontext = 4,
        Opt_labelsupport = 5,
-       Opt_nextmntopt = 6,
 };
 
-#define NUM_SEL_MNT_OPTS       (Opt_nextmntopt - 1)
-
-static const match_table_t tokens = {
-       {Opt_context, CONTEXT_STR "%s"},
-       {Opt_fscontext, FSCONTEXT_STR "%s"},
-       {Opt_defcontext, DEFCONTEXT_STR "%s"},
-       {Opt_rootcontext, ROOTCONTEXT_STR "%s"},
-       {Opt_labelsupport, LABELSUPP_STR},
-       {Opt_error, NULL},
+#define A(s, opt, has_arg) {s, sizeof(s) - 1, opt, has_arg}
+static struct {
+       const char *name;
+       int len;
+       int opt;
+       bool has_arg;
+} tokens[] = {
+       A("context", Opt_context, true),
+       A("fscontext", Opt_fscontext, true),
+       A("defcontext", Opt_defcontext, true),
+       A("rootcontext", Opt_rootcontext, true),
+       A("seclabel", Opt_labelsupport, false),
 };
+#undef A
+
+static int match_opt_prefix(char *s, int l, char **arg)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(tokens); i++) {
+               size_t len = tokens[i].len;
+               if (len > l || memcmp(s, tokens[i].name, len))
+                       continue;
+               if (tokens[i].has_arg) {
+                       if (len == l || s[len] != '=')
+                               continue;
+                       *arg = s + len + 1;
+               } else if (len != l)
+                       continue;
+               return tokens[i].opt;
+       }
+       return Opt_error;
+}
 
 #define SEL_MOUNT_FAIL_MSG "SELinux:  duplicate or incompatible mount options\n"
 
@@ -988,6 +1010,9 @@ static int selinux_add_opt(int token, const char *s, void **mnt_opts)
 {
        struct selinux_mnt_opts *opts = *mnt_opts;
 
+       if (token == Opt_labelsupport)  /* eaten and completely ignored */
+               return 0;
+
        if (!opts) {
                opts = kzalloc(sizeof(struct selinux_mnt_opts), GFP_KERNEL);
                if (!opts)
@@ -1021,36 +1046,39 @@ static int selinux_add_opt(int token, const char *s, void **mnt_opts)
        return 0;
 Einval:
        pr_warn(SEL_MOUNT_FAIL_MSG);
-       kfree(s);
        return -EINVAL;
 }
 
 static int selinux_parse_opts_str(char *options,
                                  void **mnt_opts)
 {
-       char *p;
+       char *p = options, *next;
+       int rc;
 
        /* Standard string-based options. */
-       while ((p = strsep(&options, "|")) != NULL) {
-               int token, rc;
-               substring_t args[MAX_OPT_ARGS];
-               const char *arg;
+       for (p = options; *p; p = next) {
+               int token, len;
+               char *arg = NULL;
 
-               if (!*p)
-                       continue;
-
-               token = match_token(p, tokens, args);
+               next = strchr(p, '|');
+               if (next) {
+                       len = next++ - p;
+               } else {
+                       len = strlen(p);
+                       next = p + len;
+               }
 
-               if (token == Opt_labelsupport)  /* eaten and completely ignored */
+               if (!len)
                        continue;
-               arg = match_strdup(&args[0]);
+
+               token = match_opt_prefix(p, len, &arg);
+               if (arg)
+                       arg = kmemdup_nul(arg, p + len - arg, GFP_KERNEL);
                rc = selinux_add_opt(token, arg, mnt_opts);
-               if (unlikely(rc)) {
+               if (rc) {
                        kfree(arg);
-                       if (*mnt_opts) {
-                               selinux_free_mnt_opts(*mnt_opts);
-                               *mnt_opts = NULL;
-                       }
+                       selinux_free_mnt_opts(*mnt_opts);
+                       *mnt_opts = NULL;
                        return rc;
                }
        }