From f6d8bd051c391c1c0458a30b2a7abcd939329259 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 21 Apr 2011 09:45:37 +0000 Subject: inet: add RCU protection to inet->opt We lack proper synchronization to manipulate inet->opt ip_options Problem is ip_make_skb() calls ip_setup_cork() and ip_setup_cork() possibly makes a copy of ipc->opt (struct ip_options), without any protection against another thread manipulating inet->opt. Another thread can change inet->opt pointer and free old one under us. Use RCU to protect inet->opt (changed to inet->inet_opt). Instead of handling atomic refcounts, just copy ip_options when necessary, to avoid cache line dirtying. We cant insert an rcu_head in struct ip_options since its included in skb->cb[], so this patch is large because I had to introduce a new ip_options_rcu structure. Signed-off-by: Eric Dumazet Cc: Herbert Xu Signed-off-by: David S. Miller --- net/ipv4/cipso_ipv4.c | 113 ++++++++++++++++++++++++++++---------------------- 1 file changed, 63 insertions(+), 50 deletions(-) (limited to 'net/ipv4/cipso_ipv4.c') diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c index a0af7ea87870..2b3c23c287cd 100644 --- a/net/ipv4/cipso_ipv4.c +++ b/net/ipv4/cipso_ipv4.c @@ -1857,6 +1857,11 @@ static int cipso_v4_genopt(unsigned char *buf, u32 buf_len, return CIPSO_V4_HDR_LEN + ret_val; } +static void opt_kfree_rcu(struct rcu_head *head) +{ + kfree(container_of(head, struct ip_options_rcu, rcu)); +} + /** * cipso_v4_sock_setattr - Add a CIPSO option to a socket * @sk: the socket @@ -1879,7 +1884,7 @@ int cipso_v4_sock_setattr(struct sock *sk, unsigned char *buf = NULL; u32 buf_len; u32 opt_len; - struct ip_options *opt = NULL; + struct ip_options_rcu *old, *opt = NULL; struct inet_sock *sk_inet; struct inet_connection_sock *sk_conn; @@ -1915,22 +1920,25 @@ int cipso_v4_sock_setattr(struct sock *sk, ret_val = -ENOMEM; goto socket_setattr_failure; } - memcpy(opt->__data, buf, buf_len); - opt->optlen = opt_len; - opt->cipso = sizeof(struct iphdr); + memcpy(opt->opt.__data, buf, buf_len); + opt->opt.optlen = opt_len; + opt->opt.cipso = sizeof(struct iphdr); kfree(buf); buf = NULL; sk_inet = inet_sk(sk); + + old = rcu_dereference_protected(sk_inet->inet_opt, sock_owned_by_user(sk)); if (sk_inet->is_icsk) { sk_conn = inet_csk(sk); - if (sk_inet->opt) - sk_conn->icsk_ext_hdr_len -= sk_inet->opt->optlen; - sk_conn->icsk_ext_hdr_len += opt->optlen; + if (old) + sk_conn->icsk_ext_hdr_len -= old->opt.optlen; + sk_conn->icsk_ext_hdr_len += opt->opt.optlen; sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie); } - opt = xchg(&sk_inet->opt, opt); - kfree(opt); + rcu_assign_pointer(sk_inet->inet_opt, opt); + if (old) + call_rcu(&old->rcu, opt_kfree_rcu); return 0; @@ -1960,7 +1968,7 @@ int cipso_v4_req_setattr(struct request_sock *req, unsigned char *buf = NULL; u32 buf_len; u32 opt_len; - struct ip_options *opt = NULL; + struct ip_options_rcu *opt = NULL; struct inet_request_sock *req_inet; /* We allocate the maximum CIPSO option size here so we are probably @@ -1988,15 +1996,16 @@ int cipso_v4_req_setattr(struct request_sock *req, ret_val = -ENOMEM; goto req_setattr_failure; } - memcpy(opt->__data, buf, buf_len); - opt->optlen = opt_len; - opt->cipso = sizeof(struct iphdr); + memcpy(opt->opt.__data, buf, buf_len); + opt->opt.optlen = opt_len; + opt->opt.cipso = sizeof(struct iphdr); kfree(buf); buf = NULL; req_inet = inet_rsk(req); opt = xchg(&req_inet->opt, opt); - kfree(opt); + if (opt) + call_rcu(&opt->rcu, opt_kfree_rcu); return 0; @@ -2016,34 +2025,34 @@ req_setattr_failure: * values on failure. * */ -static int cipso_v4_delopt(struct ip_options **opt_ptr) +static int cipso_v4_delopt(struct ip_options_rcu **opt_ptr) { int hdr_delta = 0; - struct ip_options *opt = *opt_ptr; + struct ip_options_rcu *opt = *opt_ptr; - if (opt->srr || opt->rr || opt->ts || opt->router_alert) { + if (opt->opt.srr || opt->opt.rr || opt->opt.ts || opt->opt.router_alert) { u8 cipso_len; u8 cipso_off; unsigned char *cipso_ptr; int iter; int optlen_new; - cipso_off = opt->cipso - sizeof(struct iphdr); - cipso_ptr = &opt->__data[cipso_off]; + cipso_off = opt->opt.cipso - sizeof(struct iphdr); + cipso_ptr = &opt->opt.__data[cipso_off]; cipso_len = cipso_ptr[1]; - if (opt->srr > opt->cipso) - opt->srr -= cipso_len; - if (opt->rr > opt->cipso) - opt->rr -= cipso_len; - if (opt->ts > opt->cipso) - opt->ts -= cipso_len; - if (opt->router_alert > opt->cipso) - opt->router_alert -= cipso_len; - opt->cipso = 0; + if (opt->opt.srr > opt->opt.cipso) + opt->opt.srr -= cipso_len; + if (opt->opt.rr > opt->opt.cipso) + opt->opt.rr -= cipso_len; + if (opt->opt.ts > opt->opt.cipso) + opt->opt.ts -= cipso_len; + if (opt->opt.router_alert > opt->opt.cipso) + opt->opt.router_alert -= cipso_len; + opt->opt.cipso = 0; memmove(cipso_ptr, cipso_ptr + cipso_len, - opt->optlen - cipso_off - cipso_len); + opt->opt.optlen - cipso_off - cipso_len); /* determining the new total option length is tricky because of * the padding necessary, the only thing i can think to do at @@ -2052,21 +2061,21 @@ static int cipso_v4_delopt(struct ip_options **opt_ptr) * from there we can determine the new total option length */ iter = 0; optlen_new = 0; - while (iter < opt->optlen) - if (opt->__data[iter] != IPOPT_NOP) { - iter += opt->__data[iter + 1]; + while (iter < opt->opt.optlen) + if (opt->opt.__data[iter] != IPOPT_NOP) { + iter += opt->opt.__data[iter + 1]; optlen_new = iter; } else iter++; - hdr_delta = opt->optlen; - opt->optlen = (optlen_new + 3) & ~3; - hdr_delta -= opt->optlen; + hdr_delta = opt->opt.optlen; + opt->opt.optlen = (optlen_new + 3) & ~3; + hdr_delta -= opt->opt.optlen; } else { /* only the cipso option was present on the socket so we can * remove the entire option struct */ *opt_ptr = NULL; - hdr_delta = opt->optlen; - kfree(opt); + hdr_delta = opt->opt.optlen; + call_rcu(&opt->rcu, opt_kfree_rcu); } return hdr_delta; @@ -2083,15 +2092,15 @@ static int cipso_v4_delopt(struct ip_options **opt_ptr) void cipso_v4_sock_delattr(struct sock *sk) { int hdr_delta; - struct ip_options *opt; + struct ip_options_rcu *opt; struct inet_sock *sk_inet; sk_inet = inet_sk(sk); - opt = sk_inet->opt; - if (opt == NULL || opt->cipso == 0) + opt = rcu_dereference_protected(sk_inet->inet_opt, 1); + if (opt == NULL || opt->opt.cipso == 0) return; - hdr_delta = cipso_v4_delopt(&sk_inet->opt); + hdr_delta = cipso_v4_delopt(&sk_inet->inet_opt); if (sk_inet->is_icsk && hdr_delta > 0) { struct inet_connection_sock *sk_conn = inet_csk(sk); sk_conn->icsk_ext_hdr_len -= hdr_delta; @@ -2109,12 +2118,12 @@ void cipso_v4_sock_delattr(struct sock *sk) */ void cipso_v4_req_delattr(struct request_sock *req) { - struct ip_options *opt; + struct ip_options_rcu *opt; struct inet_request_sock *req_inet; req_inet = inet_rsk(req); opt = req_inet->opt; - if (opt == NULL || opt->cipso == 0) + if (opt == NULL || opt->opt.cipso == 0) return; cipso_v4_delopt(&req_inet->opt); @@ -2184,14 +2193,18 @@ getattr_return: */ int cipso_v4_sock_getattr(struct sock *sk, struct netlbl_lsm_secattr *secattr) { - struct ip_options *opt; + struct ip_options_rcu *opt; + int res = -ENOMSG; - opt = inet_sk(sk)->opt; - if (opt == NULL || opt->cipso == 0) - return -ENOMSG; - - return cipso_v4_getattr(opt->__data + opt->cipso - sizeof(struct iphdr), - secattr); + rcu_read_lock(); + opt = rcu_dereference(inet_sk(sk)->inet_opt); + if (opt && opt->opt.cipso) + res = cipso_v4_getattr(opt->opt.__data + + opt->opt.cipso - + sizeof(struct iphdr), + secattr); + rcu_read_unlock(); + return res; } /** -- cgit v1.2.3-59-g8ed1b