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>

1 files changed, 55 insertions, 27 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 26ec7d67e15d..8f2285cb9029 100644
--- 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;
                 }
         }