diff options
| author | Alexei Starovoitov <ast@plumgrid.com> | 2015-10-07 20:55:41 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-10-11 14:40:05 +0300 |
| commit | ff936a04e5f28b7e0455be0e7fa91334f89e4b44 (patch) | |
| tree | f23b1f44945600ce2631560eb1f93364606b62b6 /net/core | |
| parent | d49ae37c613f7cc1f4c1fd6ef073d60c32e000dd (diff) | |
| download | linux-ff936a04e5f28b7e0455be0e7fa91334f89e4b44.tar.xz | |
bpf: fix cb access in socket filter programs
eBPF socket filter programs may see junk in 'u32 cb[5]' area,
since it could have been used by protocol layers earlier.
For socket filter programs used in af_packet we need to clean
20 bytes of skb->cb area if it could be used by the program.
For programs attached to TCP/UDP sockets we need to save/restore
these 20 bytes, since it's used by protocol layers.
Remove SK_RUN_FILTER macro, since it's no longer used.
Long term we may move this bpf cb area to per-cpu scratch, but that
requires addition of new 'per-cpu load/store' instructions,
so not suitable as a short term fix.
Fixes: d691f9e8d440 ("bpf: allow programs to write to certain skb fields")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/filter.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 342e6c8fc415..5f4cf1cffed3 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -56,10 +56,10 @@ * @sk: sock associated with &sk_buff * @skb: buffer to filter * - * Run the filter code and then cut skb->data to correct size returned by - * SK_RUN_FILTER. If pkt_len is 0 we toss packet. If skb->len is smaller + * Run the eBPF program and then cut skb->data to correct size returned by + * the program. If pkt_len is 0 we toss packet. If skb->len is smaller * than pkt_len we keep whole skb->data. This is the socket level - * wrapper to SK_RUN_FILTER. It returns 0 if the packet should + * wrapper to BPF_PROG_RUN. It returns 0 if the packet should * be accepted or -EPERM if the packet should be tossed. * */ @@ -83,7 +83,7 @@ int sk_filter(struct sock *sk, struct sk_buff *skb) rcu_read_lock(); filter = rcu_dereference(sk->sk_filter); if (filter) { - unsigned int pkt_len = SK_RUN_FILTER(filter, skb); + unsigned int pkt_len = bpf_prog_run_save_cb(filter->prog, skb); err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM; } @@ -1736,7 +1736,8 @@ static bool tc_cls_act_is_valid_access(int off, int size, static u32 bpf_net_convert_ctx_access(enum bpf_access_type type, int dst_reg, int src_reg, int ctx_off, - struct bpf_insn *insn_buf) + struct bpf_insn *insn_buf, + struct bpf_prog *prog) { struct bpf_insn *insn = insn_buf; @@ -1827,6 +1828,7 @@ static u32 bpf_net_convert_ctx_access(enum bpf_access_type type, int dst_reg, offsetof(struct __sk_buff, cb[4]): BUILD_BUG_ON(FIELD_SIZEOF(struct qdisc_skb_cb, data) < 20); + prog->cb_access = 1; ctx_off -= offsetof(struct __sk_buff, cb[0]); ctx_off += offsetof(struct sk_buff, cb); ctx_off += offsetof(struct qdisc_skb_cb, data); |