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>

1 files changed, 43 insertions, 28 deletions

diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c
index 24517055bd8e..b0a53c3b926d 100644
--- 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 =