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 55a3af8348969214976649922586b128b03e9d27..ef4c44d462935adcd9182c299a477f809ae99ccc 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 744afb4fbf84f3bb2ac6fb5641f33105ba0d04bf..12d4d2758cafc7a7d603e081ddf0a4807bdb2833 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -241,7 +241,7 @@ 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);
 
@@ -1302,7 +1302,7 @@ 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 7add261dd626b90844df54c70ca85767b39ade01..2b6c88b9a038e47d840d8b17544116084ce0c4b3 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -7267,7 +7267,7 @@ 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;