Re: [PATCH bpf-next 07/11] bpf: make sure to clear unused fields in tunnel/xfrm state fetch
From: Song Liu <hidden>
Date: 2018-05-30 17:15:35
On Sun, May 27, 2018 at 5:43 PM, Daniel Borkmann [off-list ref] wrote:
Since the remaining bits are not filled in struct bpf_tunnel_key
resp. struct bpf_xfrm_state and originate from uninitialized stack
space, we should make sure to clear them before handing control
back to the program.
Also add a padding element to struct bpf_xfrm_state for future use
similar as we have in struct bpf_tunnel_key and clear it as well.
struct bpf_xfrm_state {
__u32 reqid; /* 0 4 */
__u32 spi; /* 4 4 */
__u16 family; /* 8 2 */
/* XXX 2 bytes hole, try to pack */
union {
__u32 remote_ipv4; /* 4 */
__u32 remote_ipv6[4]; /* 16 */
}; /* 12 16 */
/* size: 28, cachelines: 1, members: 4 */
/* sum members: 26, holes: 1, sum holes: 2 */
/* last cacheline: 28 bytes */
};
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>Acked-by: Song Liu <redacted>
quoted hunk ↗ jump to hunk
--- include/uapi/linux/bpf.h | 3 ++- net/core/filter.c | 6 ++++++ 2 files changed, 8 insertions(+), 1 deletion(-)diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index e2853aa..7108711 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h@@ -2214,7 +2214,7 @@ struct bpf_tunnel_key { }; __u8 tunnel_tos; __u8 tunnel_ttl; - __u16 tunnel_ext; + __u16 tunnel_ext; /* Padding, future use. */ __u32 tunnel_label; };@@ -2225,6 +2225,7 @@ struct bpf_xfrm_state { __u32 reqid; __u32 spi; /* Stored in network byte order */ __u16 family; + __u16 ext; /* Padding, future use. */ union { __u32 remote_ipv4; /* Stored in network byte order */ __u32 remote_ipv6[4]; /* Stored in network byte order */diff --git a/net/core/filter.c b/net/core/filter.c index 717c740..5ceb5e6 100644 --- a/net/core/filter.c +++ b/net/core/filter.c@@ -3445,6 +3445,7 @@ BPF_CALL_4(bpf_skb_get_tunnel_key, struct sk_buff *, skb, struct bpf_tunnel_key to->tunnel_id = be64_to_cpu(info->key.tun_id); to->tunnel_tos = info->key.tos; to->tunnel_ttl = info->key.ttl; + to->tunnel_ext = 0; if (flags & BPF_F_TUNINFO_IPV6) { memcpy(to->remote_ipv6, &info->key.u.ipv6.src,@@ -3452,6 +3453,8 @@ BPF_CALL_4(bpf_skb_get_tunnel_key, struct sk_buff *, skb, struct bpf_tunnel_key to->tunnel_label = be32_to_cpu(info->key.label); } else { to->remote_ipv4 = be32_to_cpu(info->key.u.ipv4.src); + memset(&to->remote_ipv6[1], 0, sizeof(__u32) * 3); + to->tunnel_label = 0; } if (unlikely(size != sizeof(struct bpf_tunnel_key)))@@ -4047,11 +4050,14 @@ BPF_CALL_5(bpf_skb_get_xfrm_state, struct sk_buff *, skb, u32, index, to->reqid = x->props.reqid; to->spi = x->id.spi; to->family = x->props.family; + to->ext = 0; + if (to->family == AF_INET6) { memcpy(to->remote_ipv6, x->props.saddr.a6, sizeof(to->remote_ipv6)); } else { to->remote_ipv4 = x->props.saddr.a4; + memset(&to->remote_ipv6[1], 0, sizeof(__u32) * 3); } return 0; --2.9.5