[PATCH v2 bpf] bpf: sock recvbuff must be limited by rmem_max in bpf_setsockopt()

[Yafang Shao]

When sock recvbuff is set by bpf_setsockopt(), the value must by limited
by rmem_max.
It is the same with sendbuff.

Fixes: 8c4b4c7e9ff0 ("bpf: Add setsockopt helper function to bpf")
Acked-by: Martin KaFai Lau <ka...@fb.com>
Acked-by: Lawrence Brakmo <bra...@fb.com>
Signed-off-by: Yafang Shao <laoar.s...@gmail.com>
---
 net/core/filter.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index 7559d68..7a54dc1 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4112,10 +4112,12 @@ static unsigned long bpf_xdp_copy(void *dst_buff, const 
void *src_buff,
                /* Only some socketops are supported */
                switch (optname) {
                case SO_RCVBUF:
+                       val = min_t(u32, val, sysctl_rmem_max);
                        sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
                        sk->sk_rcvbuf = max_t(int, val * 2, SOCK_MIN_RCVBUF);
                        break;
                case SO_SNDBUF:
+                       val = min_t(u32, val, sysctl_wmem_max);
                        sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
                        sk->sk_sndbuf = max_t(int, val * 2, SOCK_MIN_SNDBUF);
                        break;
-- 
1.8.3.1