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Date: Thu, 30 Jul 2020 13:57:23 -0700
From: Martin KaFai Lau <kafai@...com>
To: <bpf@...r.kernel.org>
CC: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Eric Dumazet <edumazet@...gle.com>, <kernel-team@...com>,
Lawrence Brakmo <brakmo@...com>,
Neal Cardwell <ncardwell@...gle.com>, <netdev@...r.kernel.org>,
Yuchung Cheng <ycheng@...gle.com>
Subject: [PATCH v3 bpf-next 4/9] tcp: Add unknown_opt arg to tcp_parse_options
In the latter patch, the bpf prog only wants to be called to handle
a header option if that particular header option cannot be handled by
the kernel. This unknown option could be written by the peer's bpf-prog.
It could also be a new standard option that the running kernel does not
support it while a bpf-prog can handle it.
In a latter patch, the bpf prog will be called from tcp_validate_incoming()
if there is unknown option and a flag is set in tp->bpf_sock_ops_cb_flags.
Instead of using skb->cb[] in an earlier attempt, this patch
adds an optional arg "bool *unknown_opt" to tcp_parse_options().
The bool will be set to true if it has encountered an option
that the kernel does not recognize.
Signed-off-by: Martin KaFai Lau <kafai@...com>
---
drivers/infiniband/hw/cxgb4/cm.c | 2 +-
include/net/tcp.h | 3 ++-
net/ipv4/syncookies.c | 2 +-
net/ipv4/tcp_input.c | 40 +++++++++++++++++++++-----------
net/ipv4/tcp_minisocks.c | 4 ++--
net/ipv6/syncookies.c | 2 +-
6 files changed, 34 insertions(+), 19 deletions(-)
diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index 30e08bcc9afb..dedca6576bb9 100644
--- a/drivers/infiniband/hw/cxgb4/cm.c
+++ b/drivers/infiniband/hw/cxgb4/cm.c
@@ -3949,7 +3949,7 @@ static void build_cpl_pass_accept_req(struct sk_buff *skb, int stid , u8 tos)
*/
memset(&tmp_opt, 0, sizeof(tmp_opt));
tcp_clear_options(&tmp_opt);
- tcp_parse_options(&init_net, skb, &tmp_opt, 0, NULL);
+ tcp_parse_options(&init_net, skb, &tmp_opt, 0, NULL, NULL);
req = __skb_push(skb, sizeof(*req));
memset(req, 0, sizeof(*req));
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 895e7aabf136..d49d8f1c961a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -413,7 +413,8 @@ int tcp_mmap(struct file *file, struct socket *sock,
#endif
void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
struct tcp_options_received *opt_rx,
- int estab, struct tcp_fastopen_cookie *foc);
+ int estab, struct tcp_fastopen_cookie *foc,
+ bool *unknown_opt);
const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
/*
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 9a4f6b16c9bc..fd39aed4fcd3 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -313,7 +313,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
/* check for timestamp cookie support */
memset(&tcp_opt, 0, sizeof(tcp_opt));
- tcp_parse_options(sock_net(sk), skb, &tcp_opt, 0, NULL);
+ tcp_parse_options(sock_net(sk), skb, &tcp_opt, 0, NULL, NULL);
if (tcp_opt.saw_tstamp && tcp_opt.rcv_tsecr) {
tsoff = secure_tcp_ts_off(sock_net(sk),
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 6c38ca9de17e..d9c878001be2 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3799,7 +3799,7 @@ static void tcp_parse_fastopen_option(int len, const unsigned char *cookie,
foc->exp = exp_opt;
}
-static void smc_parse_options(const struct tcphdr *th,
+static bool smc_parse_options(const struct tcphdr *th,
struct tcp_options_received *opt_rx,
const unsigned char *ptr,
int opsize)
@@ -3808,10 +3808,13 @@ static void smc_parse_options(const struct tcphdr *th,
if (static_branch_unlikely(&tcp_have_smc)) {
if (th->syn && !(opsize & 1) &&
opsize >= TCPOLEN_EXP_SMC_BASE &&
- get_unaligned_be32(ptr) == TCPOPT_SMC_MAGIC)
+ get_unaligned_be32(ptr) == TCPOPT_SMC_MAGIC) {
opt_rx->smc_ok = 1;
+ return true;
+ }
}
#endif
+ return false;
}
/* Try to parse the MSS option from the TCP header. Return 0 on failure, clamped
@@ -3864,7 +3867,8 @@ static u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss)
void tcp_parse_options(const struct net *net,
const struct sk_buff *skb,
struct tcp_options_received *opt_rx, int estab,
- struct tcp_fastopen_cookie *foc)
+ struct tcp_fastopen_cookie *foc,
+ bool *unknown_opt)
{
const unsigned char *ptr;
const struct tcphdr *th = tcp_hdr(skb);
@@ -3962,15 +3966,23 @@ void tcp_parse_options(const struct net *net,
*/
if (opsize >= TCPOLEN_EXP_FASTOPEN_BASE &&
get_unaligned_be16(ptr) ==
- TCPOPT_FASTOPEN_MAGIC)
+ TCPOPT_FASTOPEN_MAGIC) {
tcp_parse_fastopen_option(opsize -
TCPOLEN_EXP_FASTOPEN_BASE,
ptr + 2, th->syn, foc, true);
- else
- smc_parse_options(th, opt_rx, ptr,
- opsize);
+ break;
+ }
+
+ if (smc_parse_options(th, opt_rx, ptr, opsize))
+ break;
+
+ if (unknown_opt)
+ *unknown_opt = true;
break;
+ default:
+ if (unknown_opt)
+ *unknown_opt = true;
}
ptr += opsize-2;
length -= opsize;
@@ -4003,7 +4015,8 @@ static bool tcp_parse_aligned_timestamp(struct tcp_sock *tp, const struct tcphdr
*/
static bool tcp_fast_parse_options(const struct net *net,
const struct sk_buff *skb,
- const struct tcphdr *th, struct tcp_sock *tp)
+ const struct tcphdr *th, struct tcp_sock *tp,
+ bool *unknown_opt)
{
/* In the spirit of fast parsing, compare doff directly to constant
* values. Because equality is used, short doff can be ignored here.
@@ -4017,7 +4030,7 @@ static bool tcp_fast_parse_options(const struct net *net,
return true;
}
- tcp_parse_options(net, skb, &tp->rx_opt, 1, NULL);
+ tcp_parse_options(net, skb, &tp->rx_opt, 1, NULL, unknown_opt);
if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
tp->rx_opt.rcv_tsecr -= tp->tsoffset;
@@ -5492,9 +5505,10 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
{
struct tcp_sock *tp = tcp_sk(sk);
bool rst_seq_match = false;
+ bool unknown_opt = false;
/* RFC1323: H1. Apply PAWS check first. */
- if (tcp_fast_parse_options(sock_net(sk), skb, th, tp) &&
+ if (tcp_fast_parse_options(sock_net(sk), skb, th, tp, &unknown_opt) &&
tp->rx_opt.saw_tstamp &&
tcp_paws_discard(sk, skb)) {
if (!th->rst) {
@@ -5866,7 +5880,7 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
/* Get original SYNACK MSS value if user MSS sets mss_clamp */
tcp_clear_options(&opt);
opt.user_mss = opt.mss_clamp = 0;
- tcp_parse_options(sock_net(sk), synack, &opt, 0, NULL);
+ tcp_parse_options(sock_net(sk), synack, &opt, 0, NULL, NULL);
mss = opt.mss_clamp;
}
@@ -5951,7 +5965,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
int saved_clamp = tp->rx_opt.mss_clamp;
bool fastopen_fail;
- tcp_parse_options(sock_net(sk), skb, &tp->rx_opt, 0, &foc);
+ tcp_parse_options(sock_net(sk), skb, &tp->rx_opt, 0, &foc, NULL);
if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
tp->rx_opt.rcv_tsecr -= tp->tsoffset;
@@ -6685,7 +6699,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
tmp_opt.mss_clamp = af_ops->mss_clamp;
tmp_opt.user_mss = tp->rx_opt.user_mss;
tcp_parse_options(sock_net(sk), skb, &tmp_opt, 0,
- want_cookie ? NULL : &foc);
+ want_cookie ? NULL : &foc, NULL);
if (want_cookie && !tmp_opt.saw_tstamp)
tcp_clear_options(&tmp_opt);
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 495dda2449fe..61f9194802c4 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -98,7 +98,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
tmp_opt.saw_tstamp = 0;
if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) {
- tcp_parse_options(twsk_net(tw), skb, &tmp_opt, 0, NULL);
+ tcp_parse_options(twsk_net(tw), skb, &tmp_opt, 0, NULL, NULL);
if (tmp_opt.saw_tstamp) {
if (tmp_opt.rcv_tsecr)
@@ -580,7 +580,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
tmp_opt.saw_tstamp = 0;
if (th->doff > (sizeof(struct tcphdr)>>2)) {
- tcp_parse_options(sock_net(sk), skb, &tmp_opt, 0, NULL);
+ tcp_parse_options(sock_net(sk), skb, &tmp_opt, 0, NULL, NULL);
if (tmp_opt.saw_tstamp) {
tmp_opt.ts_recent = req->ts_recent;
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 13235a012388..f22961a73c2b 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -157,7 +157,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
/* check for timestamp cookie support */
memset(&tcp_opt, 0, sizeof(tcp_opt));
- tcp_parse_options(sock_net(sk), skb, &tcp_opt, 0, NULL);
+ tcp_parse_options(sock_net(sk), skb, &tcp_opt, 0, NULL, NULL);
if (tcp_opt.saw_tstamp && tcp_opt.rcv_tsecr) {
tsoff = secure_tcpv6_ts_off(sock_net(sk),
--
2.24.1
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