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Date: Tue, 12 Oct 2021 14:57:03 +0800
From: Liu Jian <liujian56@...wei.com>
To: <john.fastabend@...il.com>, <daniel@...earbox.net>,
<jakub@...udflare.com>, <lmb@...udflare.com>,
<davem@...emloft.net>, <kuba@...nel.org>, <ast@...nel.org>,
<andrii@...nel.org>, <kafai@...com>, <songliubraving@...com>,
<yhs@...com>, <kpsingh@...nel.org>, <netdev@...r.kernel.org>,
<bpf@...r.kernel.org>, <xiyou.wangcong@...il.com>
CC: <liujian56@...wei.com>
Subject: [PATHC bpf v5 1/3] skmsg: lose offset info in sk_psock_skb_ingress
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 suggestion, 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@...wei.com>
Reviewed-by: Cong Wang <cong.wang@...edance.com>
Acked-by: John Fastabend <john.fastabend@...il.com>
---
v1->v2: fix build error when disable CONFIG_BPF_STREAM_PARSER
v2->v3: Add one bit in skb->_sk_redir to distinguish enable or disable strparser
v3->v4: Remove "#if IS_ENABLED(CONFIG_BPF_STREAM_PARSER)" code;
and let "stm" have a more precise scope.
v4->v5: Add fix tag.
include/linux/skmsg.h | 18 ++++++++++++++++--
net/core/skmsg.c | 40 ++++++++++++++++++++++++++++++----------
2 files changed, 46 insertions(+), 12 deletions(-)
diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
index 14ab0c0bc924..94e2a1f6e58d 100644
--- a/include/linux/skmsg.h
+++ b/include/linux/skmsg.h
@@ -508,8 +508,22 @@ 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 2d6249b28928..e85b7f8491b9 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -494,6 +494,7 @@ 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)
@@ -507,11 +508,11 @@ 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;
@@ -522,9 +523,11 @@ 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;
@@ -535,7 +538,7 @@ 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;
@@ -547,7 +550,7 @@ 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;
@@ -557,7 +560,8 @@ 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;
@@ -567,7 +571,7 @@ 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;
@@ -581,7 +585,7 @@ 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,
@@ -624,6 +628,12 @@ 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);
@@ -930,6 +940,7 @@ 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:
@@ -949,7 +960,15 @@ 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);
@@ -1018,6 +1037,7 @@ static void sk_psock_strp_read(struct strparser *strp, struct sk_buff *skb)
ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
skb->sk = NULL;
}
+ skb_bpf_set_strparser(skb);
sk_psock_verdict_apply(psock, skb, ret);
out:
rcu_read_unlock();
--
2.17.1
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