dm verity: separate function for parsing opt args

Move optional argument parsing into a separate function to make it
easier to add more of them without making verity_ctr even longer.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c
index 2451705..b0a53c3 100644 (file)
--- a/drivers/md/dm-verity.c
+++ b/drivers/md/dm-verity.c
@@ -34,6 +34,8 @@
 #define DM_VERITY_OPT_LOGGING          "ignore_corruption"
 #define DM_VERITY_OPT_RESTART          "restart_on_corruption"
 
+#define DM_VERITY_OPTS_MAX             1
+
 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
 
 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
@@ -721,6 +723,44 @@ static void verity_dtr(struct dm_target *ti)
        kfree(v);
 }
 
+static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
+{
+       int r;
+       unsigned argc;
+       struct dm_target *ti = v->ti;
+       const char *arg_name;
+
+       static struct dm_arg _args[] = {
+               {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
+       };
+
+       r = dm_read_arg_group(_args, as, &argc, &ti->error);
+       if (r)
+               return -EINVAL;
+
+       if (!argc)
+               return 0;
+
+       do {
+               arg_name = dm_shift_arg(as);
+               argc--;
+
+               if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
+                       v->mode = DM_VERITY_MODE_LOGGING;
+                       continue;
+
+               } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
+                       v->mode = DM_VERITY_MODE_RESTART;
+                       continue;
+               }
+
+               ti->error = "Unrecognized verity feature request";
+               return -EINVAL;
+       } while (argc && !r);
+
+       return r;
+}
+
 /*
  * Target parameters:
  *     <version>       The current format is version 1.
@@ -739,18 +779,13 @@ static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 {
        struct dm_verity *v;
        struct dm_arg_set as;
-       const char *opt_string;
-       unsigned int num, opt_params;
+       unsigned int num;
        unsigned long long num_ll;
        int r;
        int i;
        sector_t hash_position;
        char dummy;
 
-       static struct dm_arg _args[] = {
-               {0, 1, "Invalid number of feature args"},
-       };
-
        v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
        if (!v) {
                ti->error = "Cannot allocate verity structure";
@@ -895,29 +930,9 @@ static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
                as.argc = argc;
                as.argv = argv;
 
-               r = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
-               if (r)
+               r = verity_parse_opt_args(&as, v);
+               if (r < 0)
                        goto bad;
-
-               while (opt_params) {
-                       opt_params--;
-                       opt_string = dm_shift_arg(&as);
-                       if (!opt_string) {
-                               ti->error = "Not enough feature arguments";
-                               r = -EINVAL;
-                               goto bad;
-                       }
-
-                       if (!strcasecmp(opt_string, DM_VERITY_OPT_LOGGING))
-                               v->mode = DM_VERITY_MODE_LOGGING;
-                       else if (!strcasecmp(opt_string, DM_VERITY_OPT_RESTART))
-                               v->mode = DM_VERITY_MODE_RESTART;
-                       else {
-                               ti->error = "Invalid feature arguments";
-                               r = -EINVAL;
-                               goto bad;
-                       }
-               }
        }
 
        v->hash_per_block_bits =