selinux: new helper - selinux_add_opt()

the guts of the loop in selinux_parse_opts_str() - takes one
(already recognized) option and adds it to growing selinux_mnt_opts.

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

1 files changed, 53 insertions, 73 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 238907d69e8b..26ec7d67e15d 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -984,97 +984,77 @@ out:
         return rc;
 }
 
+static int selinux_add_opt(int token, const char *s, void **mnt_opts)
+{
+        struct selinux_mnt_opts *opts = *mnt_opts;
+
+        if (!opts) {
+                opts = kzalloc(sizeof(struct selinux_mnt_opts), GFP_KERNEL);
+                if (!opts)
+                        return -ENOMEM;
+                *mnt_opts = opts;
+        }
+        if (!s)
+                return -ENOMEM;
+        switch (token) {
+        case Opt_context:
+                if (opts->context || opts->defcontext)
+                        goto Einval;
+                opts->context = s;
+                break;
+        case Opt_fscontext:
+                if (opts->fscontext)
+                        goto Einval;
+                opts->fscontext = s;
+                break;
+        case Opt_rootcontext:
+                if (opts->rootcontext)
+                        goto Einval;
+                opts->rootcontext = s;
+                break;
+        case Opt_defcontext:
+                if (opts->context || opts->defcontext)
+                        goto Einval;
+                opts->defcontext = s;
+                break;
+        }
+        return 0;
+Einval:
+        pr_warn(SEL_MOUNT_FAIL_MSG);
+        kfree(s);
+        return -EINVAL;
+}
+
 static int selinux_parse_opts_str(char *options,
                                   void **mnt_opts)
 {
-        struct selinux_mnt_opts *opts = *mnt_opts;
         char *p;
-        int rc;
 
         /* Standard string-based options. */
         while ((p = strsep(&options, "|")) != NULL) {
-                int token;
+                int token, rc;
                 substring_t args[MAX_OPT_ARGS];
+                const char *arg;
 
                 if (!*p)
                         continue;
 
                 token = match_token(p, tokens, args);
 
-                if (!opts) {
-                        opts = kzalloc(sizeof(struct selinux_mnt_opts), GFP_KERNEL);
-                        if (!opts)
-                                return -ENOMEM;
-                }
-
-                switch (token) {
-                case Opt_context:
-                        if (opts->context || opts->defcontext) {
-                                rc = -EINVAL;
-                                pr_warn(SEL_MOUNT_FAIL_MSG);
-                                goto out_err;
-                        }
-                        opts->context = match_strdup(&args[0]);
-                        if (!opts->context) {
-                                rc = -ENOMEM;
-                                goto out_err;
-                        }
-                        break;
-
-                case Opt_fscontext:
-                        if (opts->fscontext) {
-                                rc = -EINVAL;
-                                pr_warn(SEL_MOUNT_FAIL_MSG);
-                                goto out_err;
-                        }
-                        opts->fscontext = match_strdup(&args[0]);
-                        if (!opts->fscontext) {
-                                rc = -ENOMEM;
-                                goto out_err;
-                        }
-                        break;
-
-                case Opt_rootcontext:
-                        if (opts->rootcontext) {
-                                rc = -EINVAL;
-                                pr_warn(SEL_MOUNT_FAIL_MSG);
-                                goto out_err;
-                        }
-                        opts->rootcontext = match_strdup(&args[0]);
-                        if (!opts->rootcontext) {
-                                rc = -ENOMEM;
-                                goto out_err;
-                        }
-                        break;
-
-                case Opt_defcontext:
-                        if (opts->context || opts->defcontext) {
-                                rc = -EINVAL;
-                                pr_warn(SEL_MOUNT_FAIL_MSG);
-                                goto out_err;
-                        }
-                        opts->defcontext = match_strdup(&args[0]);
-                        if (!opts->defcontext) {
-                                rc = -ENOMEM;
-                                goto out_err;
+                if (token == Opt_labelsupport)  /* eaten and completely ignored */
+                        continue;
+                arg = match_strdup(&args[0]);
+                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;
                         }
-                        break;
-                case Opt_labelsupport:
-                        break;
-                default:
-                        rc = -EINVAL;
-                        pr_warn("SELinux:  unknown mount option\n");
-                        goto out_err;
-
+                        return rc;
                 }
         }
-        *mnt_opts = opts;
         return 0;
-
-out_err:
-        if (opts)
-                selinux_free_mnt_opts(opts);
-        return rc;
 }
 
 static int show_sid(struct seq_file *m, u32 sid)