diff mbox series

[net-next,5/5] tcp: handle rstreason in tcp_check_req()

Message ID 20240509131306.92931-6-kerneljasonxing@gmail.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series tcp: support rstreasons in the passive logic | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 2950 this patch: 2950
netdev/build_tools success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers success CCed 5 of 5 maintainers
netdev/build_clang success Errors and warnings before: 979 this patch: 979
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 3141 this patch: 3141
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 28 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 1 this patch: 1
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-05-10--00-00 (tests: 1009)

Commit Message

Jason Xing May 9, 2024, 1:13 p.m. UTC 
From: Jason Xing <kernelxing@tencent.com>

We're going to send an RST due to invalid syn packet which is already
checked whether 1) it is in sequence, 2) it is a retransmitted skb.

As RFC 793 says, if the state of socket is not CLOSED/LISTEN/SYN-SENT,
then we should send an RST when receiving bad syn packet:
"fourth, check the SYN bit,...If the SYN is in the window it is an
error, send a reset"

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 include/net/rstreason.h  | 8 ++++++++
 net/ipv4/tcp_minisocks.c | 2 +-
 2 files changed, 9 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/include/net/rstreason.h b/include/net/rstreason.h
index 62e869089da4..bfea05ff8d88 100644
--- a/include/net/rstreason.h
+++ b/include/net/rstreason.h
@@ -16,6 +16,7 @@ 
 	FN(TCP_OLD_ACK)			\
 	FN(TCP_ABORT_ON_DATA)		\
 	FN(TCP_TIMEWAIT_SOCKET)		\
+	FN(INVALID_SYN)			\
 	FN(MPTCP_RST_EUNSPEC)		\
 	FN(MPTCP_RST_EMPTCP)		\
 	FN(MPTCP_RST_ERESOURCE)		\
@@ -73,6 +74,13 @@  enum sk_rst_reason {
 	/* Here start with the independent reasons */
 	/** @SK_RST_REASON_TCP_TIMEWAIT_SOCKET: happen on the timewait socket */
 	SK_RST_REASON_TCP_TIMEWAIT_SOCKET,
+	/**
+	 * @SK_RST_REASON_INVALID_SYN: receive bad syn packet
+	 * RFC 793 says if the state is not CLOSED/LISTEN/SYN-SENT then
+	 * "fourth, check the SYN bit,...If the SYN is in the window it is
+	 * an error, send a reset"
+	 */
+	SK_RST_REASON_INVALID_SYN,
 
 	/* Copy from include/uapi/linux/mptcp.h.
 	 * These reset fields will not be changed since they adhere to
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 7d543569a180..b93619b2384b 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -879,7 +879,7 @@  struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 		 * avoid becoming vulnerable to outside attack aiming at
 		 * resetting legit local connections.
 		 */
-		req->rsk_ops->send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
+		req->rsk_ops->send_reset(sk, skb, SK_RST_REASON_INVALID_SYN);
 	} else if (fastopen) { /* received a valid RST pkt */
 		reqsk_fastopen_remove(sk, req, true);
 		tcp_reset(sk, skb);