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>

12 files changed, 26 insertions, 17 deletions

diff --git a/include/net/ip.h b/include/net/ip.h
index 217bc5bfc6c6..5a25f36fe3a7 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -473,7 +473,7 @@ int compat_ip_getsockopt(struct sock *sk, int level, int optname,
 int ip_ra_control(struct sock *sk, unsigned char on,
                   void (*destructor)(struct sock *));
 
-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);
 void ip_icmp_error(struct sock *sk, struct sk_buff *skb, int err, __be16 port,
                    u32 info, u8 *payload);
 void ip_local_error(struct sock *sk, int err, __be32 daddr, __be16 dport,
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 2a5f668cd683..eb198acaac1d 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -776,8 +776,10 @@ int compat_ipv6_getsockopt(struct sock *sk, int level, int optname,
 
 int ip6_datagram_connect(struct sock *sk, struct sockaddr *addr, int addr_len);
 
-int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len);
-int ipv6_recv_rxpmtu(struct sock *sk, struct msghdr *msg, int len);
+int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len,
+                    int *addr_len);
+int ipv6_recv_rxpmtu(struct sock *sk, struct msghdr *msg, int len,
+                     int *addr_len);
 void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err, __be16 port,
                      u32 info, u8 *payload);
 void ipv6_local_error(struct sock *sk, int err, struct flowi6 *fl6, u32 info);
diff --git a/include/net/ping.h b/include/net/ping.h
index 3f67704f3747..90f48417b03d 100644
--- a/include/net/ping.h
+++ b/include/net/ping.h
@@ -31,7 +31,8 @@
 
 /* Compatibility glue so we can support IPv6 when it's compiled as a module */
 struct pingv6_ops {
-        int (*ipv6_recv_error)(struct sock *sk, struct msghdr *msg, int len);
+        int (*ipv6_recv_error)(struct sock *sk, struct msghdr *msg, int len,
+                               int *addr_len);
         int (*ip6_datagram_recv_ctl)(struct sock *sk, struct msghdr *msg,
                                      struct sk_buff *skb);
         int (*icmpv6_err_convert)(u8 type, u8 code, int *err);
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),
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index a454b0ff57c7..d690204a0275 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -318,7 +318,7 @@ void ipv6_local_rxpmtu(struct sock *sk, struct flowi6 *fl6, u32 mtu)
 /*
  *      Handle MSG_ERRQUEUE
  */
-int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len)
+int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
 {
         struct ipv6_pinfo *np = inet6_sk(sk);
         struct sock_exterr_skb *serr;
@@ -369,6 +369,7 @@ int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len)
                                                &sin->sin6_addr);
                         sin->sin6_scope_id = 0;
                 }
+                *addr_len = sizeof(*sin);
         }
 
         memcpy(&errhdr.ee, &serr->ee, sizeof(struct sock_extended_err));
@@ -423,7 +424,8 @@ EXPORT_SYMBOL_GPL(ipv6_recv_error);
 /*
  *      Handle IPV6_RECVPATHMTU
  */
-int ipv6_recv_rxpmtu(struct sock *sk, struct msghdr *msg, int len)
+int ipv6_recv_rxpmtu(struct sock *sk, struct msghdr *msg, int len,
+                     int *addr_len)
 {
         struct ipv6_pinfo *np = inet6_sk(sk);
         struct sk_buff *skb;
@@ -457,6 +459,7 @@ int ipv6_recv_rxpmtu(struct sock *sk, struct msghdr *msg, int len)
                 sin->sin6_port = 0;
                 sin->sin6_scope_id = mtu_info.ip6m_addr.sin6_scope_id;
                 sin->sin6_addr = mtu_info.ip6m_addr.sin6_addr;
+                *addr_len = sizeof(*sin);
         }
 
         put_cmsg(msg, SOL_IPV6, IPV6_PATHMTU, sizeof(mtu_info), &mtu_info);
diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index 8815e31a87fe..a83243c3d656 100644
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -57,7 +57,8 @@ static struct inet_protosw pingv6_protosw = {
 
 
 /* Compatibility glue so we can support IPv6 when it's compiled as a module */
-static int dummy_ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len)
+static int dummy_ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len,
+                                 int *addr_len)
 {
         return -EAFNOSUPPORT;
 }
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index e24ff1df0401..7fb4e14c467f 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -466,10 +466,10 @@ static int rawv6_recvmsg(struct kiocb *iocb, struct sock *sk,
                 return -EOPNOTSUPP;
 
         if (flags & MSG_ERRQUEUE)
-                return ipv6_recv_error(sk, msg, len);
+                return ipv6_recv_error(sk, msg, len, addr_len);
 
         if (np->rxpmtu && np->rxopt.bits.rxpmtu)
-                return ipv6_recv_rxpmtu(sk, msg, len);
+                return ipv6_recv_rxpmtu(sk, msg, len, addr_len);
 
         skb = skb_recv_datagram(sk, flags, noblock, &err);
         if (!skb)
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 81eb8cf8389b..bcd5699313c3 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -393,10 +393,10 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
         bool slow;
 
         if (flags & MSG_ERRQUEUE)
-                return ipv6_recv_error(sk, msg, len);
+                return ipv6_recv_error(sk, msg, len, addr_len);
 
         if (np->rxpmtu && np->rxopt.bits.rxpmtu)
-                return ipv6_recv_rxpmtu(sk, msg, len);
+                return ipv6_recv_rxpmtu(sk, msg, len, addr_len);
 
 try_again:
         skb = __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index cfd65304be60..d9b437e55007 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -665,7 +665,7 @@ static int l2tp_ip6_recvmsg(struct kiocb *iocb, struct sock *sk,
                 *addr_len = sizeof(*lsa);
 
         if (flags & MSG_ERRQUEUE)
-                return ipv6_recv_error(sk, msg, len);
+                return ipv6_recv_error(sk, msg, len, addr_len);
 
         skb = skb_recv_datagram(sk, flags, noblock, &err);
         if (!skb)