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authorMartin KaFai Lau <kafai@fb.com>2020-07-08 23:11:04 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2020-07-09 22:03:31 +0200
commitf3dda7a679df183e798b86e7b6ec05ab35476de3 (patch)
tree5546f846bf465d85da12656e19b9fa40d20c180b /kernel/bpf
parent365f9ae4ee36037e2a9268fe7296065356840b4c (diff)
bpf: net: Avoid copying sk_user_data of reuseport_array during sk_clone
It makes little sense for copying sk_user_data of reuseport_array during sk_clone_lock(). This patch reuses the SK_USER_DATA_NOCOPY bit introduced in commit f1ff5ce2cd5e ("net, sk_msg: Clear sk_user_data pointer on clone if tagged"). It is used to mark the sk_user_data is not supposed to be copied to its clone. Although the cloned sk's sk_user_data will not be used/freed in bpf_sk_reuseport_detach(), this change can still allow the cloned sk's sk_user_data to be used by some other means. Freeing the reuseport_array's sk_user_data does not require a rcu grace period. Thus, the existing rcu_assign_sk_user_data_nocopy() is not used. Fixes: 5dc4c4b7d4e8 ("bpf: Introduce BPF_MAP_TYPE_REUSEPORT_SOCKARRAY") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com> Link: https://lore.kernel.org/bpf/20200709061104.4018798-1-kafai@fb.com
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/reuseport_array.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/kernel/bpf/reuseport_array.c b/kernel/bpf/reuseport_array.c
index 21cde24386db..a95bc8d7e812 100644
--- a/kernel/bpf/reuseport_array.c
+++ b/kernel/bpf/reuseport_array.c
@@ -20,11 +20,14 @@ static struct reuseport_array *reuseport_array(struct bpf_map *map)
/* The caller must hold the reuseport_lock */
void bpf_sk_reuseport_detach(struct sock *sk)
{
- struct sock __rcu **socks;
+ uintptr_t sk_user_data;
write_lock_bh(&sk->sk_callback_lock);
- socks = sk->sk_user_data;
- if (socks) {
+ sk_user_data = (uintptr_t)sk->sk_user_data;
+ if (sk_user_data) {
+ struct sock __rcu **socks;
+
+ socks = (void *)(sk_user_data & SK_USER_DATA_PTRMASK);
WRITE_ONCE(sk->sk_user_data, NULL);
/*
* Do not move this NULL assignment outside of
@@ -252,6 +255,7 @@ int bpf_fd_reuseport_array_update_elem(struct bpf_map *map, void *key,
struct sock *free_osk = NULL, *osk, *nsk;
struct sock_reuseport *reuse;
u32 index = *(u32 *)key;
+ uintptr_t sk_user_data;
struct socket *socket;
int err, fd;
@@ -305,7 +309,8 @@ int bpf_fd_reuseport_array_update_elem(struct bpf_map *map, void *key,
if (err)
goto put_file_unlock;
- WRITE_ONCE(nsk->sk_user_data, &array->ptrs[index]);
+ sk_user_data = (uintptr_t)&array->ptrs[index] | SK_USER_DATA_NOCOPY;
+ WRITE_ONCE(nsk->sk_user_data, (void *)sk_user_data);
rcu_assign_pointer(array->ptrs[index], nsk);
free_osk = osk;
err = 0;