From 33cf7c90fe2f97afb1cadaa0cfb782cb9d1b9ee2 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 11 Mar 2015 18:53:14 -0700 Subject: net: add real socket cookies A long standing problem in netlink socket dumps is the use of kernel socket addresses as cookies. 1) It is a security concern. 2) Sockets can be reused quite quickly, so there is no guarantee a cookie is used once and identify a flow. 3) request sock, establish sock, and timewait socks for a given flow have different cookies. Part of our effort to bring better TCP statistics requires to switch to a different allocator. In this patch, I chose to use a per network namespace 64bit generator, and to use it only in the case a socket needs to be dumped to netlink. (This might be refined later if needed) Note that I tried to carry cookies from request sock, to establish sock, then timewait sockets. Signed-off-by: Eric Dumazet Cc: Eric Salo Signed-off-by: David S. Miller --- net/core/sock.c | 1 + net/core/sock_diag.c | 37 +++++++++++++++++++++++++++---------- net/dccp/ipv4.c | 2 ++ net/ipv4/inet_connection_sock.c | 2 ++ net/ipv4/inet_diag.c | 14 +++++++++----- net/ipv4/inet_timewait_sock.c | 1 + net/ipv4/syncookies.c | 1 + net/ipv4/tcp_input.c | 2 ++ 8 files changed, 45 insertions(+), 15 deletions(-) (limited to 'net') diff --git a/net/core/sock.c b/net/core/sock.c index 726e1f99aa8d..a9a9c2ff9260 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1538,6 +1538,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority) newsk->sk_err = 0; newsk->sk_priority = 0; newsk->sk_incoming_cpu = raw_smp_processor_id(); + atomic64_set(&newsk->sk_cookie, 0); /* * Before updating sk_refcnt, we must commit prior changes to memory * (Documentation/RCU/rculist_nulls.txt for details) diff --git a/net/core/sock_diag.c b/net/core/sock_diag.c index 96e70ee05a8d..74dddf84adcd 100644 --- a/net/core/sock_diag.c +++ b/net/core/sock_diag.c @@ -13,22 +13,39 @@ static const struct sock_diag_handler *sock_diag_handlers[AF_MAX]; static int (*inet_rcv_compat)(struct sk_buff *skb, struct nlmsghdr *nlh); static DEFINE_MUTEX(sock_diag_table_mutex); -int sock_diag_check_cookie(void *sk, const __u32 *cookie) +static u64 sock_gen_cookie(struct sock *sk) { - if ((cookie[0] != INET_DIAG_NOCOOKIE || - cookie[1] != INET_DIAG_NOCOOKIE) && - ((u32)(unsigned long)sk != cookie[0] || - (u32)((((unsigned long)sk) >> 31) >> 1) != cookie[1])) - return -ESTALE; - else + while (1) { + u64 res = atomic64_read(&sk->sk_cookie); + + if (res) + return res; + res = atomic64_inc_return(&sock_net(sk)->cookie_gen); + atomic64_cmpxchg(&sk->sk_cookie, 0, res); + } +} + +int sock_diag_check_cookie(struct sock *sk, const __u32 *cookie) +{ + u64 res; + + if (cookie[0] == INET_DIAG_NOCOOKIE && cookie[1] == INET_DIAG_NOCOOKIE) return 0; + + res = sock_gen_cookie(sk); + if ((u32)res != cookie[0] || (u32)(res >> 32) != cookie[1]) + return -ESTALE; + + return 0; } EXPORT_SYMBOL_GPL(sock_diag_check_cookie); -void sock_diag_save_cookie(void *sk, __u32 *cookie) +void sock_diag_save_cookie(struct sock *sk, __u32 *cookie) { - cookie[0] = (u32)(unsigned long)sk; - cookie[1] = (u32)(((unsigned long)sk >> 31) >> 1); + u64 res = sock_gen_cookie(sk); + + cookie[0] = (u32)res; + cookie[1] = (u32)(res >> 32); } EXPORT_SYMBOL_GPL(sock_diag_save_cookie); diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c index e45b968613a4..207281ae3536 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -641,6 +641,8 @@ int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) ireq = inet_rsk(req); ireq->ir_loc_addr = ip_hdr(skb)->daddr; ireq->ir_rmt_addr = ip_hdr(skb)->saddr; + ireq->ireq_net = sock_net(sk); + atomic64_set(&ireq->ir_cookie, 0); /* * Step 3: Process LISTEN state diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 14d02ea905b6..34581f928afa 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -678,6 +678,8 @@ struct sock *inet_csk_clone_lock(const struct sock *sk, newsk->sk_write_space = sk_stream_write_space; newsk->sk_mark = inet_rsk(req)->ir_mark; + atomic64_set(&newsk->sk_cookie, + atomic64_read(&inet_rsk(req)->ir_cookie)); newicsk->icsk_retransmits = 0; newicsk->icsk_backoff = 0; diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c index ac3bfb458afd..29317ff4a007 100644 --- a/net/ipv4/inet_diag.c +++ b/net/ipv4/inet_diag.c @@ -221,12 +221,13 @@ static int inet_csk_diag_fill(struct sock *sk, user_ns, portid, seq, nlmsg_flags, unlh); } -static int inet_twsk_diag_fill(struct inet_timewait_sock *tw, +static int inet_twsk_diag_fill(struct sock *sk, struct sk_buff *skb, const struct inet_diag_req_v2 *req, u32 portid, u32 seq, u16 nlmsg_flags, const struct nlmsghdr *unlh) { + struct inet_timewait_sock *tw = inet_twsk(sk); struct inet_diag_msg *r; struct nlmsghdr *nlh; s32 tmo; @@ -247,7 +248,7 @@ static int inet_twsk_diag_fill(struct inet_timewait_sock *tw, r->idiag_retrans = 0; r->id.idiag_if = tw->tw_bound_dev_if; - sock_diag_save_cookie(tw, r->id.idiag_cookie); + sock_diag_save_cookie(sk, r->id.idiag_cookie); r->id.idiag_sport = tw->tw_sport; r->id.idiag_dport = tw->tw_dport; @@ -283,7 +284,7 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, const struct nlmsghdr *unlh) { if (sk->sk_state == TCP_TIME_WAIT) - return inet_twsk_diag_fill(inet_twsk(sk), skb, r, portid, seq, + return inet_twsk_diag_fill(sk, skb, r, portid, seq, nlmsg_flags, unlh); return inet_csk_diag_fill(sk, skb, r, user_ns, portid, seq, @@ -675,7 +676,7 @@ static int inet_twsk_diag_dump(struct sock *sk, if (!inet_diag_bc_sk(bc, sk)) return 0; - return inet_twsk_diag_fill(inet_twsk(sk), skb, r, + return inet_twsk_diag_fill(sk, skb, r, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq, NLM_F_MULTI, cb->nlh); } @@ -734,7 +735,10 @@ static int inet_diag_fill_req(struct sk_buff *skb, struct sock *sk, r->idiag_retrans = req->num_retrans; r->id.idiag_if = sk->sk_bound_dev_if; - sock_diag_save_cookie(req, r->id.idiag_cookie); + + BUILD_BUG_ON(offsetof(struct inet_request_sock, ir_cookie) != + offsetof(struct sock, sk_cookie)); + sock_diag_save_cookie((struct sock *)ireq, r->id.idiag_cookie); tmo = req->expires - jiffies; if (tmo < 0) diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c index 6d592f8555fb..2bd980526631 100644 --- a/net/ipv4/inet_timewait_sock.c +++ b/net/ipv4/inet_timewait_sock.c @@ -195,6 +195,7 @@ struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int stat tw->tw_ipv6only = 0; tw->tw_transparent = inet->transparent; tw->tw_prot = sk->sk_prot_creator; + atomic64_set(&tw->tw_cookie, atomic64_read(&sk->sk_cookie)); twsk_net_set(tw, hold_net(sock_net(sk))); /* * Because we use RCU lookups, we should not set tw_refcnt diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c index 45fe60c5238e..ece31b426013 100644 --- a/net/ipv4/syncookies.c +++ b/net/ipv4/syncookies.c @@ -346,6 +346,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb) req->ts_recent = tcp_opt.saw_tstamp ? tcp_opt.rcv_tsval : 0; treq->snt_synack = tcp_opt.saw_tstamp ? tcp_opt.rcv_tsecr : 0; treq->listener = NULL; + ireq->ireq_net = sock_net(sk); /* We throwed the options of the initial SYN away, so we hope * the ACK carries the same options again (see RFC1122 4.2.3.8) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index fb4cf8b8e121..d7045f5f6ebf 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5965,6 +5965,8 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, tmp_opt.tstamp_ok = tmp_opt.saw_tstamp; tcp_openreq_init(req, &tmp_opt, skb, sk); + inet_rsk(req)->ireq_net = sock_net(sk); + atomic64_set(&inet_rsk(req)->ir_cookie, 0); af_ops->init_req(req, sk, skb); -- cgit v1.2.3-59-g8ed1b