[PATCH net-next v4 7/8] net: tcp: add skb drop reasons to route_req()

menglong8.dong
2022-06-17T10:07:01Z

Add skb drop reasons to the route_req() in struct tcp_request_sock_ops.
Following functions are involved:

tcp_v4_route_req()
tcp_v6_route_req()
subflow_v4_route_req()
subflow_v6_route_req()

And the new reason SKB_DROP_REASON_LSM is added, which is used when
skb is dropped by LSM.

Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
include/net/dropreason.h | 2 ++
include/net/tcp.h | 3 ++-
net/ipv4/tcp_input.c | 2 +-
net/ipv4/tcp_ipv4.c | 14 +++++++++++---
net/ipv6/tcp_ipv6.c | 14 +++++++++++---
net/mptcp/subflow.c | 10 ++++++----
6 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/include/net/dropreason.h b/include/net/dropreason.h
index 90cdb7321926..d3143598125e 100644
--- a/include/net/dropreason.h
+++ b/include/net/dropreason.h
@@ -252,6 +252,8 @@ enum skb_drop_reason {
* 'SYN' packet
*/
SKB_DROP_REASON_TIMEWAIT,
+ /** @SKB_DROP_REASON_LSM: dropped by LSM */
+ SKB_DROP_REASON_LSM,
/**
* @SKB_DROP_REASON_MAX: the maximum of drop reason, which shouldn't be
* used as a real 'reason'
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 1a88fabf0cce..d8895076d448 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2073,7 +2073,8 @@ struct tcp_request_sock_ops {
struct dst_entry *(*route_req)(const struct sock *sk,
struct sk_buff *skb,
struct flowi *fl,
- struct request_sock *req);
+ struct request_sock *req,
+ enum skb_drop_reason *reason);
u32 (*init_seq)(const struct sk_buff *skb);
u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 8617e7a8f841..ed55616bc2a0 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6945,7 +6945,7 @@ enum skb_drop_reason tcp_conn_request(struct request_sock_ops *rsk_ops,
/* Note: tcp_v6_init_req() might override ir_iif for link locals */
inet_rsk(req)->ir_iif = inet_request_bound_dev_if(sk, skb);

- dst = af_ops->route_req(sk, skb, &fl, req);
+ dst = af_ops->route_req(sk, skb, &fl, req, &reason);
if (!dst)
goto drop_and_free;

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index f2ed9763d504..8accb49f3808 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1423,14 +1423,22 @@ static void tcp_v4_init_req(struct request_sock *req,
static struct dst_entry *tcp_v4_route_req(const struct sock *sk,
struct sk_buff *skb,
struct flowi *fl,
- struct request_sock *req)
+ struct request_sock *req,
+ enum skb_drop_reason *reason)
{
+ struct dst_entry *dst;
+
tcp_v4_init_req(req, sk, skb);

- if (security_inet_conn_request(sk, skb, req))
+ if (security_inet_conn_request(sk, skb, req)) {
+ SKB_DR_SET(*reason, LSM);
return NULL;
+ }

- return inet_csk_route_req(sk, &fl->u.ip4, req);
+ dst = inet_csk_route_req(sk, &fl->u.ip4, req);
+ if (!dst)
+ SKB_DR_SET(*reason, IP_OUTNOROUTES);
+ return dst;
}

struct request_sock_ops tcp_request_sock_ops __read_mostly = {
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 9aeb0a7b7c12..fbe37f4a73ee 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -802,14 +802,22 @@ static void tcp_v6_init_req(struct request_sock *req,
static struct dst_entry *tcp_v6_route_req(const struct sock *sk,
struct sk_buff *skb,
struct flowi *fl,
- struct request_sock *req)
+ struct request_sock *req,
+ enum skb_drop_reason *reason)
{
+ struct dst_entry *dst;
+
tcp_v6_init_req(req, sk, skb);

- if (security_inet_conn_request(sk, skb, req))
+ if (security_inet_conn_request(sk, skb, req)) {
+ SKB_DR_SET(*reason, LSM);
return NULL;
+ }

- return inet6_csk_route_req(sk, &fl->u.ip6, req, IPPROTO_TCP);
+ dst = inet6_csk_route_req(sk, &fl->u.ip6, req, IPPROTO_TCP);
+ if (!dst)
+ SKB_DR_SET(*reason, IP_OUTNOROUTES);
+ return dst;
}

struct request_sock_ops tcp6_request_sock_ops __read_mostly = {
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 5a1d05c3a1ef..654cc602ff2c 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -285,7 +285,8 @@ EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
struct sk_buff *skb,
struct flowi *fl,
- struct request_sock *req)
+ struct request_sock *req,
+ enum skb_drop_reason *reason)
{
struct dst_entry *dst;
int err;
@@ -293,7 +294,7 @@ static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
tcp_rsk(req)->is_mptcp = 1;
subflow_init_req(req, sk);

- dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req);
+ dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req, reason);
if (!dst)
return NULL;

@@ -311,7 +312,8 @@ static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
struct sk_buff *skb,
struct flowi *fl,
- struct request_sock *req)
+ struct request_sock *req,
+ enum skb_drop_reason *reason)
{
struct dst_entry *dst;
int err;
@@ -319,7 +321,7 @@ static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
tcp_rsk(req)->is_mptcp = 1;
subflow_init_req(req, sk);

- dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req);
+ dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req, reason);
if (!dst)
return NULL;

--
2.36.1