[PATCH 5.15 560/917] skmsg: Lose offset info in sk_psock_skb_ingress

Greg Kroah-Hartman
2021-11-15T23:51:20Z

From: Liu Jian <liujian56@huawei.com>

[ Upstream commit 7303524e04af49a47991e19f895c3b8cdc3796c7 ]

If sockmap enable strparser, there are lose offset info in
sk_psock_skb_ingress(). If the length determined by parse_msg function is not
skb->len, the skb will be converted to sk_msg multiple times, and userspace
app will get the data multiple times.

Fix this by get the offset and length from strp_msg. And as Cong suggested,
add one bit in skb->_sk_redir to distinguish enable or disable strparser.

Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Cong Wang <cong.wang@bytedance.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20211029141216.211899-1-liujian56@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/skmsg.h | 18 ++++++++++++++++--
net/core/skmsg.c | 43 +++++++++++++++++++++++++++++++++----------
2 files changed, 49 insertions(+), 12 deletions(-)

diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
index 1ce9a9eb223b6..b4256847c7079 100644
--- a/include/linux/skmsg.h
+++ b/include/linux/skmsg.h
@@ -509,8 +509,22 @@ static inline bool sk_psock_strp_enabled(struct sk_psock *psock)

#if IS_ENABLED(CONFIG_NET_SOCK_MSG)

-/* We only have one bit so far. */
-#define BPF_F_PTR_MASK ~(BPF_F_INGRESS)
+#define BPF_F_STRPARSER (1UL << 1)
+
+/* We only have two bits so far. */
+#define BPF_F_PTR_MASK ~(BPF_F_INGRESS | BPF_F_STRPARSER)
+
+static inline bool skb_bpf_strparser(const struct sk_buff *skb)
+{
+ unsigned long sk_redir = skb->_sk_redir;
+
+ return sk_redir & BPF_F_STRPARSER;
+}
+
+static inline void skb_bpf_set_strparser(struct sk_buff *skb)
+{
+ skb->_sk_redir |= BPF_F_STRPARSER;
+}

static inline bool skb_bpf_ingress(const struct sk_buff *skb)
{
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index a86ef7e844f8c..1ae52ac943f62 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -508,6 +508,7 @@ static struct sk_msg *sk_psock_create_ingress_msg(struct sock *sk,
}

static int sk_psock_skb_ingress_enqueue(struct sk_buff *skb,
+ u32 off, u32 len,
struct sk_psock *psock,
struct sock *sk,
struct sk_msg *msg)
@@ -521,11 +522,11 @@ static int sk_psock_skb_ingress_enqueue(struct sk_buff *skb,
*/
if (skb_linearize(skb))
return -EAGAIN;
- num_sge = skb_to_sgvec(skb, msg->sg.data, 0, skb->len);
+ num_sge = skb_to_sgvec(skb, msg->sg.data, off, len);
if (unlikely(num_sge < 0))
return num_sge;

- copied = skb->len;
+ copied = len;
msg->sg.start = 0;
msg->sg.size = copied;
msg->sg.end = num_sge;
@@ -536,9 +537,11 @@ static int sk_psock_skb_ingress_enqueue(struct sk_buff *skb,
return copied;
}

-static int sk_psock_skb_ingress_self(struct sk_psock *psock, struct sk_buff *skb);
+static int sk_psock_skb_ingress_self(struct sk_psock *psock, struct sk_buff *skb,
+ u32 off, u32 len);

-static int sk_psock_skb_ingress(struct sk_psock *psock, struct sk_buff *skb)
+static int sk_psock_skb_ingress(struct sk_psock *psock, struct sk_buff *skb,
+ u32 off, u32 len)
{
struct sock *sk = psock->sk;
struct sk_msg *msg;
@@ -549,7 +552,7 @@ static int sk_psock_skb_ingress(struct sk_psock *psock, struct sk_buff *skb)
* correctly.
*/
if (unlikely(skb->sk == sk))
- return sk_psock_skb_ingress_self(psock, skb);
+ return sk_psock_skb_ingress_self(psock, skb, off, len);
msg = sk_psock_create_ingress_msg(sk, skb);
if (!msg)
return -EAGAIN;
@@ -561,7 +564,7 @@ static int sk_psock_skb_ingress(struct sk_psock *psock, struct sk_buff *skb)
* into user buffers.
*/
skb_set_owner_r(skb, sk);
- err = sk_psock_skb_ingress_enqueue(skb, psock, sk, msg);
+ err = sk_psock_skb_ingress_enqueue(skb, off, len, psock, sk, msg);
if (err < 0)
kfree(msg);
return err;
@@ -571,7 +574,8 @@ static int sk_psock_skb_ingress(struct sk_psock *psock, struct sk_buff *skb)
* skb. In this case we do not need to check memory limits or skb_set_owner_r
* because the skb is already accounted for here.
*/
-static int sk_psock_skb_ingress_self(struct sk_psock *psock, struct sk_buff *skb)
+static int sk_psock_skb_ingress_self(struct sk_psock *psock, struct sk_buff *skb,
+ u32 off, u32 len)
{
struct sk_msg *msg = kzalloc(sizeof(*msg), __GFP_NOWARN | GFP_ATOMIC);
struct sock *sk = psock->sk;
@@ -581,7 +585,7 @@ static int sk_psock_skb_ingress_self(struct sk_psock *psock, struct sk_buff *skb
return -EAGAIN;
sk_msg_init(msg);
skb_set_owner_r(skb, sk);
- err = sk_psock_skb_ingress_enqueue(skb, psock, sk, msg);
+ err = sk_psock_skb_ingress_enqueue(skb, off, len, psock, sk, msg);
if (err < 0)
kfree(msg);
return err;
@@ -595,7 +599,7 @@ static int sk_psock_handle_skb(struct sk_psock *psock, struct sk_buff *skb,
return -EAGAIN;
return skb_send_sock(psock->sk, skb, off, len);
}
- return sk_psock_skb_ingress(psock, skb);
+ return sk_psock_skb_ingress(psock, skb, off, len);
}

static void sk_psock_skb_state(struct sk_psock *psock,
@@ -638,6 +642,12 @@ static void sk_psock_backlog(struct work_struct *work)
while ((skb = skb_dequeue(&psock->ingress_skb))) {
len = skb->len;
off = 0;
+ if (skb_bpf_strparser(skb)) {
+ struct strp_msg *stm = strp_msg(skb);
+
+ off = stm->offset;
+ len = stm->full_len;
+ }
start:
ingress = skb_bpf_ingress(skb);
skb_bpf_redirect_clear(skb);
@@ -877,6 +887,7 @@ static int sk_psock_skb_redirect(struct sk_psock *from, struct sk_buff *skb)
* return code, but then didn't set a redirect interface.
*/
if (unlikely(!sk_other)) {
+ skb_bpf_redirect_clear(skb);
sock_drop(from->sk, skb);
return -EIO;
}
@@ -944,6 +955,7 @@ static int sk_psock_verdict_apply(struct sk_psock *psock, struct sk_buff *skb,
{
struct sock *sk_other;
int err = 0;
+ u32 len, off;

switch (verdict) {
case __SK_PASS:
@@ -951,6 +963,7 @@ static int sk_psock_verdict_apply(struct sk_psock *psock, struct sk_buff *skb,
sk_other = psock->sk;
if (sock_flag(sk_other, SOCK_DEAD) ||
!sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)) {
+ skb_bpf_redirect_clear(skb);
goto out_free;
}

@@ -963,7 +976,15 @@ static int sk_psock_verdict_apply(struct sk_psock *psock, struct sk_buff *skb,
* retrying later from workqueue.
*/
if (skb_queue_empty(&psock->ingress_skb)) {
- err = sk_psock_skb_ingress_self(psock, skb);
+ len = skb->len;
+ off = 0;
+ if (skb_bpf_strparser(skb)) {
+ struct strp_msg *stm = strp_msg(skb);
+
+ off = stm->offset;
+ len = stm->full_len;
+ }
+ err = sk_psock_skb_ingress_self(psock, skb, off, len);
}
if (err < 0) {
spin_lock_bh(&psock->ingress_lock);
@@ -1029,6 +1050,8 @@ static void sk_psock_strp_read(struct strparser *strp, struct sk_buff *skb)
skb_dst_drop(skb);
skb_bpf_redirect_clear(skb);
ret = bpf_prog_run_pin_on_cpu(prog, skb);
+ if (ret == SK_PASS)
+ skb_bpf_set_strparser(skb);
ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
skb->sk = NULL;
}
--
2.33.0