KEYS: DNS: Use key preparsing

Make use of key preparsing in the DNS resolver so that quota size determination
can take place prior to keyring locking when a key is being added.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>

1 files changed, 25 insertions, 18 deletions

diff --git a/net/dns_resolver/dns_key.c b/net/dns_resolver/dns_key.c
index bf8584339048..f380b2c58178 100644
--- a/net/dns_resolver/dns_key.c
+++ b/net/dns_resolver/dns_key.c
@@ -46,7 +46,7 @@ const struct cred *dns_resolver_cache;
 #define DNS_ERRORNO_OPTION      "dnserror"
 
 /*
- * Instantiate a user defined key for dns_resolver.
+ * Preparse instantiation data for a dns_resolver key.
  *
  * The data must be a NUL-terminated string, with the NUL char accounted in
  * datalen.
@@ -58,17 +58,15 @@ const struct cred *dns_resolver_cache;
  *        "ip1,ip2,...#foo=bar"
  */
 static int
-dns_resolver_instantiate(struct key *key, struct key_preparsed_payload *prep)
+dns_resolver_preparse(struct key_preparsed_payload *prep)
 {
         struct user_key_payload *upayload;
         unsigned long derrno;
         int ret;
-        size_t datalen = prep->datalen, result_len = 0;
+        int datalen = prep->datalen, result_len = 0;
         const char *data = prep->data, *end, *opt;
 
-        kenter("%%%d,%s,'%*.*s',%zu",
-               key->serial, key->description,
-               (int)datalen, (int)datalen, data, datalen);
+        kenter("'%*.*s',%u", datalen, datalen, data, datalen);
 
         if (datalen <= 1 || !data || data[datalen - 1] != '\0')
                 return -EINVAL;
@@ -95,8 +93,7 @@ dns_resolver_instantiate(struct key *key, struct key_preparsed_payload *prep)
                         opt_len = next_opt - opt;
                         if (!opt_len) {
                                 printk(KERN_WARNING
-                                       "Empty option to dns_resolver key %d\n",
-                                       key->serial);
+                                       "Empty option to dns_resolver key\n");
                                 return -EINVAL;
                         }
 
@@ -125,30 +122,28 @@ dns_resolver_instantiate(struct key *key, struct key_preparsed_payload *prep)
                                         goto bad_option_value;
 
                                 kdebug("dns error no. = %lu", derrno);
-                                key->type_data.x[0] = -derrno;
+                                prep->type_data[0] = ERR_PTR(-derrno);
                                 continue;
                         }
 
                 bad_option_value:
                         printk(KERN_WARNING
-                               "Option '%*.*s' to dns_resolver key %d:"
+                               "Option '%*.*s' to dns_resolver key:"
                                " bad/missing value\n",
-                               opt_nlen, opt_nlen, opt, key->serial);
+                               opt_nlen, opt_nlen, opt);
                         return -EINVAL;
                 } while (opt = next_opt + 1, opt < end);
         }
 
         /* don't cache the result if we're caching an error saying there's no
          * result */
-        if (key->type_data.x[0]) {
-                kleave(" = 0 [h_error %ld]", key->type_data.x[0]);
+        if (prep->type_data[0]) {
+                kleave(" = 0 [h_error %ld]", PTR_ERR(prep->type_data[0]));
                 return 0;
         }
 
         kdebug("store result");
-        ret = key_payload_reserve(key, result_len);
-        if (ret < 0)
-                return -EINVAL;
+        prep->quotalen = result_len;
 
         upayload = kmalloc(sizeof(*upayload) + result_len + 1, GFP_KERNEL);
         if (!upayload) {
@@ -159,13 +154,23 @@ dns_resolver_instantiate(struct key *key, struct key_preparsed_payload *prep)
         upayload->datalen = result_len;
         memcpy(upayload->data, data, result_len);
         upayload->data[result_len] = '\0';
-        rcu_assign_pointer(key->payload.data, upayload);
 
+        prep->payload[0] = upayload;
         kleave(" = 0");
         return 0;
 }
 
 /*
+ * Clean up the preparse data
+ */
+static void dns_resolver_free_preparse(struct key_preparsed_payload *prep)
+{
+        pr_devel("==>%s()\n", __func__);
+
+        kfree(prep->payload[0]);
+}
+
+/*
  * The description is of the form "[<type>:]<domain_name>"
  *
  * The domain name may be a simple name or an absolute domain name (which
@@ -234,7 +239,9 @@ static long dns_resolver_read(const struct key *key,
 
 struct key_type key_type_dns_resolver = {
         .name           = "dns_resolver",
-        .instantiate    = dns_resolver_instantiate,
+        .preparse       = dns_resolver_preparse,
+        .free_preparse  = dns_resolver_free_preparse,
+        .instantiate    = generic_key_instantiate,
         .match          = dns_resolver_match,
         .revoke         = user_revoke,
         .destroy        = user_destroy,