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Message-ID: <20240703122758.i6lt_jii@linutronix.de>
Date: Wed, 3 Jul 2024 14:27:58 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Jakub Kicinski <kuba@...nel.org>
Cc: syzbot <syzbot+08811615f0e17bc6708b@...kaller.appspotmail.com>,
andrii@...nel.org, ast@...nel.org, bpf@...r.kernel.org,
daniel@...earbox.net, davem@...emloft.net, eddyz87@...il.com,
haoluo@...gle.com, hawk@...nel.org, john.fastabend@...il.com,
jolsa@...nel.org, kpsingh@...nel.org, linux-kernel@...r.kernel.org,
martin.lau@...ux.dev, netdev@...r.kernel.org, sdf@...ichev.me,
song@...nel.org, syzkaller-bugs@...glegroups.com,
yonghong.song@...ux.dev
Subject: [PATCH net-net] tun: Assign missing bpf_net_context.
During the introduction of struct bpf_net_context handling for
XDP-redirect, the tun driver has been missed.
Set the bpf_net_context before invoking BPF XDP program within the TUN
driver.
Reported-by: syzbot+0b5c75599f1d872bea6f@...kaller.appspotmail.com
Reported-by: syzbot+5ae46b237278e2369cac@...kaller.appspotmail.com
Reported-by: syzbot+c1e04a422bbc0f0f2921@...kaller.appspotmail.com
Fixes: 401cb7dae8130 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
drivers/net/tun.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 9254bca2813dc..df4dd6b7479e1 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1661,6 +1661,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
int len, int *skb_xdp)
{
struct page_frag *alloc_frag = ¤t->task_frag;
+ struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
struct bpf_prog *xdp_prog;
int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
char *buf;
@@ -1700,6 +1701,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
local_bh_disable();
rcu_read_lock();
+ bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
xdp_prog = rcu_dereference(tun->xdp_prog);
if (xdp_prog) {
struct xdp_buff xdp;
@@ -1728,12 +1730,14 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
pad = xdp.data - xdp.data_hard_start;
len = xdp.data_end - xdp.data;
}
+ bpf_net_ctx_clear(bpf_net_ctx);
rcu_read_unlock();
local_bh_enable();
return __tun_build_skb(tfile, alloc_frag, buf, buflen, len, pad);
out:
+ bpf_net_ctx_clear(bpf_net_ctx);
rcu_read_unlock();
local_bh_enable();
return NULL;
@@ -1914,20 +1918,24 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
skb_record_rx_queue(skb, tfile->queue_index);
if (skb_xdp) {
+ struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
struct bpf_prog *xdp_prog;
int ret;
local_bh_disable();
rcu_read_lock();
+ bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
xdp_prog = rcu_dereference(tun->xdp_prog);
if (xdp_prog) {
ret = do_xdp_generic(xdp_prog, &skb);
if (ret != XDP_PASS) {
+ bpf_net_ctx_clear(bpf_net_ctx);
rcu_read_unlock();
local_bh_enable();
goto unlock_frags;
}
}
+ bpf_net_ctx_clear(bpf_net_ctx);
rcu_read_unlock();
local_bh_enable();
}
@@ -2566,6 +2574,7 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
ctl && ctl->type == TUN_MSG_PTR) {
+ struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
struct tun_page tpage;
int n = ctl->num;
int flush = 0, queued = 0;
@@ -2574,6 +2583,7 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
local_bh_disable();
rcu_read_lock();
+ bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
for (i = 0; i < n; i++) {
xdp = &((struct xdp_buff *)ctl->ptr)[i];
@@ -2588,6 +2598,7 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
if (tfile->napi_enabled && queued > 0)
napi_schedule(&tfile->napi);
+ bpf_net_ctx_clear(bpf_net_ctx);
rcu_read_unlock();
local_bh_enable();
--
2.45.2
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