inet: stop leaking jiffies on the wire

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>

diff --git a/drivers/crypto/chelsio/chtls/chtls_cm.c b/drivers/crypto/chelsio/chtls/chtls_cm.c
index 774d991d7cca49011016d41c00914ad84059ccb8..aca75237bbcf83eb1d440bcdf1e4d3b702cff0a1 100644 (file)
--- a/drivers/crypto/chelsio/chtls/chtls_cm.c
+++ b/drivers/crypto/chelsio/chtls/chtls_cm.c
@@ -1297,7 +1297,7 @@ static void make_established(struct sock *sk, u32 snd_isn, unsigned int opt)
        tp->write_seq = snd_isn;
        tp->snd_nxt = snd_isn;
        tp->snd_una = snd_isn;
-       inet_sk(sk)->inet_id = tp->write_seq ^ jiffies;
+       inet_sk(sk)->inet_id = prandom_u32();
        assign_rxopt(sk, opt);
 
        if (tp->rcv_wnd > (RCV_BUFSIZ_M << 10))

diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index d9b4200ed12df8ecc7ff7de26827207c5a290e37..0d8f782c25ccc031e5322beccb0242ee42b032b9 100644 (file)
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -117,7 +117,7 @@ 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 9a0fe0c2fa02c9707e6fc8c02529a48e84f7d680..4a8550c49202db13b17d5cf4ed1e44dd8852c212 100644 (file)
--- a/net/ipv4/datagram.c
+++ b/net/ipv4/datagram.c
@@ -73,7 +73,7 @@ int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len
        reuseport_has_conns(sk, true);
        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 b7419269595591d7055a4a032580e115fd7fd72b..67b2dc7a17274bd4cdadd01c45a9afdc66dc01d3 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -303,7 +303,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
                                                 inet->inet_daddr);
        }
 
-       inet->inet_id = tp->write_seq ^ jiffies;
+       inet->inet_id = prandom_u32();
 
        if (tcp_fastopen_defer_connect(sk, &err))
                return err;
@@ -1450,7 +1450,7 @@ 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 ca81e06df1651f16ab332cd9fc880c21b89a5c6d..ffd3262b7a41eac2e3d825c3f0665066f376ea3c 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -9306,7 +9306,7 @@ 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;