[PATCH net-next 9/9] net: tcp: add skb drop reasons to route_req()

menglong8.dong
2022-05-16T03:47:23Z

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/linux/skbuff.h | 4 ++++
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, 35 insertions(+), 12 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 8d18fc5a5af6..fdfe54dc5ae4 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -564,6 +564,9 @@ struct sk_buff;
* SKB_DROP_REASON_TIMEWAIT
* socket is in time-wait state and all packet that received will
* be treated as 'drop', except a good 'SYN' packet
+ *
+ * SKB_DROP_REASON_LSM
+ * dropped by LSM
*/
#define __DEFINE_SKB_DROP_REASON(FN) \
FN(NOT_SPECIFIED) \
@@ -636,6 +639,7 @@ struct sk_buff;
FN(LISTENOVERFLOWS) \
FN(TCP_REQQFULLDROP) \
FN(TIMEWAIT) \
+ FN(LSM) \
FN(MAX)

/* The reason of skb drop, which is used in kfree_skb_reason().
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 88217b8d95ac..ed57c331fdeb 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2075,7 +2075,8 @@ 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 be6275c56b59..146d22b05186 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6950,7 +6950,7 @@ 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 9174ee162633..510664ec2a06 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 5c777006de3d..7292f60e668a 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 267f4e47236a..8661d314ec12 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