inet: stop leaking jiffies on the wire

[ Upstream commit a904a0693c189691eeee64f6c6b188bd7dc244e9 ]

Historically linux tried to stick to RFC 791, 1122, 2003
for IPv4 ID field generation.

RFC 6864 made clear that no matter how hard we try,
we can not ensure unicity of IP ID within maximum
lifetime for all datagrams with a given source
address/destination address/protocol tuple.

Linux uses a per socket inet generator (inet_id), initialized
at connection startup with a XOR of 'jiffies' and other
fields that appear clear on the wire.

Thiemo Nagel pointed that this strategy is a privacy
concern as this provides 16 bits of entropy to fingerprint
devices.

Let's switch to a random starting point, this is just as
good as far as RFC 6864 is concerned and does not leak
anything critical.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Thiemo Nagel <tnagel@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index bdf90838b83f874b0673965dcead40bd74c25bd1..322268b88fec39b1ba793d500d9d923d4503a077 100644 (file)
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -121,7 +121,7 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
                                                    inet->inet_daddr,
                                                    inet->inet_sport,
                                                    inet->inet_dport);
-       inet->inet_id = dp->dccps_iss ^ jiffies;
+       inet->inet_id = prandom_u32();
 
        err = dccp_connect(sk);
        rt = NULL;

diff --git a/net/ipv4/datagram.c b/net/ipv4/datagram.c
index f915abff1350a86af8d5bb89725b751c061b0fb5..d3eddfd138753615623418b80345d2d9b397cb36 100644 (file)
--- a/net/ipv4/datagram.c
+++ b/net/ipv4/datagram.c
@@ -75,7 +75,7 @@ int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len
        inet->inet_dport = usin->sin_port;
        sk->sk_state = TCP_ESTABLISHED;
        sk_set_txhash(sk);
-       inet->inet_id = jiffies;
+       inet->inet_id = prandom_u32();
 
        sk_dst_set(sk, &rt->dst);
        err = 0;

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 848f2c1da8a5f4a38c22e1f46649df89d7117957..cced424e11765a04e5fbdf234e834c9fed57eb65 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -239,7 +239,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
                                                           inet->inet_sport,
                                                           usin->sin_port);
 
-       inet->inet_id = tp->write_seq ^ jiffies;
+       inet->inet_id = prandom_u32();
 
        err = tcp_connect(sk);
 
@@ -1307,7 +1307,7 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
        inet_csk(newsk)->icsk_ext_hdr_len = 0;
        if (inet_opt)
                inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
-       newinet->inet_id = newtp->write_seq ^ jiffies;
+       newinet->inet_id = prandom_u32();
 
        if (!dst) {
                dst = inet_csk_route_child_sock(sk, newsk, req);

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index c952abf2253567d710f35e7b0c20a6c1b7aaf073..21ec92011585ad820f6aca60bb9c3993bd879d38 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -7734,7 +7734,7 @@ void sctp_copy_sock(struct sock *newsk, struct sock *sk,
        newinet->inet_rcv_saddr = inet->inet_rcv_saddr;
        newinet->inet_dport = htons(asoc->peer.port);
        newinet->pmtudisc = inet->pmtudisc;
-       newinet->inet_id = asoc->next_tsn ^ jiffies;
+       newinet->inet_id = prandom_u32();
 
        newinet->uc_ttl = inet->uc_ttl;
        newinet->mc_loop = 1;