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bpf: make sure to clear unused fields in tunnel/xfrm state fetch 

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 <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel Borkmann 2018-06-02 23:06:37 +02:00 committed by Alexei Starovoitov
parent cb20b08ead
commit 1fbc2e0cfc
2 changed files with 8 additions and 1 deletions
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3
include/uapi/linux/bpf.h
View File

@ -2268,7 +2268,7 @@ struct bpf_tunnel_key {
};
__u8 tunnel_tos;
__u8 tunnel_ttl;
__u16 tunnel_ext;
__u16 tunnel_ext; /* Padding, future use. */
__u32 tunnel_label;
};
@ -2279,6 +2279,7 @@ 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 */

6
net/core/filter.c
View File

@ -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;