[PATCH net] packet: validate msg_namelen in send directly

[Willem de Bruijn]

From: Willem de Bruijn <will...@google.com>

Packet sockets in datagram mode take a destination address. Verify its
length before passing to dev_hard_header.

Prior to 2.6.14-rc3, the send code ignored sll_halen. This is
established behavior. Directly compare msg_namelen to dev->addr_len.

Fixes: 6b8d95f1795c4 ("packet: validate address length if non-zero")
Suggested-by: David Laight <david.lai...@aculab.com>
Signed-off-by: Willem de Bruijn <will...@google.com>
---
 net/packet/af_packet.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 9419c5cf4de5e..13301e36b4a28 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2624,10 +2624,13 @@ static int tpacket_snd(struct packet_sock *po, struct 
msghdr *msg)
                                                sll_addr)))
                        goto out;
                proto   = saddr->sll_protocol;
-               addr    = saddr->sll_halen ? saddr->sll_addr : NULL;
                dev = dev_get_by_index(sock_net(&po->sk), saddr->sll_ifindex);
-               if (addr && dev && saddr->sll_halen < dev->addr_len)
-                       goto out_put;
+               if (po->sk.sk_socket->type == SOCK_DGRAM) {
+                       addr = saddr->sll_addr;
+                       if (dev && msg->msg_namelen < dev->addr_len +
+                                       offsetof(struct sockaddr_ll, sll_addr))
+                               goto out_put;
+               }
        }
 
        err = -ENXIO;
@@ -2824,10 +2827,13 @@ static int packet_snd(struct socket *sock, struct 
msghdr *msg, size_t len)
                if (msg->msg_namelen < (saddr->sll_halen + offsetof(struct 
sockaddr_ll, sll_addr)))
                        goto out;
                proto   = saddr->sll_protocol;
-               addr    = saddr->sll_halen ? saddr->sll_addr : NULL;
                dev = dev_get_by_index(sock_net(sk), saddr->sll_ifindex);
-               if (addr && dev && saddr->sll_halen < dev->addr_len)
-                       goto out_unlock;
+               if (sock->type == SOCK_DGRAM) {
+                       addr = saddr->sll_addr;
+                       if (dev && msg->msg_namelen < dev->addr_len +
+                                       offsetof(struct sockaddr_ll, sll_addr))
+                               goto out_unlock;
+               }
        }
 
        err = -ENXIO;
-- 
2.21.0.593.g511ec345e18-goog