inet: fix addr_len/msg->msg_namelen assignment in recv_error and rxpmtu functions

Commit bceaa90240b6019ed73b49965eac7d167610be69 ("inet: prevent leakage
of uninitialized memory to user in recv syscalls") conditionally updated
addr_len if the msg_name is written to. The recv_error and rxpmtu
functions relied on the recvmsg functions to set up addr_len before.

As this does not happen any more we have to pass addr_len to those
functions as well and set it to the size of the corresponding sockaddr
length.

This broke traceroute and such.

Fixes: bceaa90240b6 ("inet: prevent leakage of uninitialized memory to user in recv syscalls")
Reported-by: Brad Spengler <spender@grsecurity.net>
Reported-by: Tom Labanowski
Cc: mpb <mpb.mail@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 7 insertions, 5 deletions

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 3f858266fa7e..ddf32a6bc415 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -386,7 +386,7 @@ void ip_local_error(struct sock *sk, int err, __be32 daddr, __be16 port, u32 inf
 /*
  *      Handle MSG_ERRQUEUE
  */
-int ip_recv_error(struct sock *sk, struct msghdr *msg, int len)
+int ip_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
 {
         struct sock_exterr_skb *serr;
         struct sk_buff *skb, *skb2;
@@ -423,6 +423,7 @@ int ip_recv_error(struct sock *sk, struct msghdr *msg, int len)
                                                    serr->addr_offset);
                 sin->sin_port = serr->port;
                 memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
+                *addr_len = sizeof(*sin);
         }
 
         memcpy(&errhdr.ee, &serr->ee, sizeof(struct sock_extended_err));
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 876c6ca2d8f9..840cf1b9e6ee 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -841,10 +841,11 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
         if (flags & MSG_ERRQUEUE) {
                 if (family == AF_INET) {
-                        return ip_recv_error(sk, msg, len);
+                        return ip_recv_error(sk, msg, len, addr_len);
 #if IS_ENABLED(CONFIG_IPV6)
                 } else if (family == AF_INET6) {
-                        return pingv6_ops.ipv6_recv_error(sk, msg, len);
+                        return pingv6_ops.ipv6_recv_error(sk, msg, len,
+                                                          addr_len);
 #endif
                 }
         }
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 5cb8ddb505ee..23c3e5b5bb53 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -697,7 +697,7 @@ static int raw_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 goto out;
 
         if (flags & MSG_ERRQUEUE) {
-                err = ip_recv_error(sk, msg, len);
+                err = ip_recv_error(sk, msg, len, addr_len);
                 goto out;
         }
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 5944d7d668dd..44dfaa09b584 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1236,7 +1236,7 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
         bool slow;
 
         if (flags & MSG_ERRQUEUE)
-                return ip_recv_error(sk, msg, len);
+                return ip_recv_error(sk, msg, len, addr_len);
 
 try_again:
         skb = __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),