[NETLINK]: introduce NLA_BINARY type

This patch introduces a new NLA_BINARY attribute policy type with the
verification of simply checking the maximum length of the payload.

It also fixes a small typo in the example.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 8 insertions, 1 deletions

diff --git a/include/net/netlink.h b/include/net/netlink.h
index 1c11518fc822..2e4c90a98a7f 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -171,6 +171,7 @@ enum {
         NLA_MSECS,
         NLA_NESTED,
         NLA_NUL_STRING,
+        NLA_BINARY,
         __NLA_TYPE_MAX,
 };
 
@@ -188,12 +189,13 @@ enum {
  *    NLA_STRING           Maximum length of string
  *    NLA_NUL_STRING       Maximum length of string (excluding NUL)
  *    NLA_FLAG             Unused
+ *    NLA_BINARY           Maximum length of attribute payload
  *    All other            Exact length of attribute payload
  *
  * Example:
  * static struct nla_policy my_policy[ATTR_MAX+1] __read_mostly = {
  *      [ATTR_FOO] = { .type = NLA_U16 },
- *      [ATTR_BAR] = { .type = NLA_STRING, len = BARSIZ },
+ *      [ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ },
  *      [ATTR_BAZ] = { .len = sizeof(struct mystruct) },
  * };
  */
diff --git a/net/netlink/attr.c b/net/netlink/attr.c
index 004139557e09..df5f820a4c32 100644
--- a/net/netlink/attr.c
+++ b/net/netlink/attr.c
@@ -67,6 +67,11 @@ static int validate_nla(struct nlattr *nla, int maxtype,
                 }
                 break;
 
+        case NLA_BINARY:
+                if (pt->len && attrlen > pt->len)
+                        return -ERANGE;
+                break;
+
         default:
                 if (pt->len)
                         minlen = pt->len;