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| author | Daniel Borkmann <daniel@iogearbox.net> | 2016-03-16 01:42:49 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-03-18 19:38:46 -0400 |
| commit | 09c37a2c5bbc28b5fbc07a01db4bccdbd0a5d8a2 (patch) | |
| tree | 22860981936d3b36e2cae1bdf22a46c996958bb2 /net/core | |
| parent | 019ded3aa7c9799fbe6533baeac9aafc7063bd39 (diff) | |
| download | lwn-09c37a2c5bbc28b5fbc07a01db4bccdbd0a5d8a2.tar.gz lwn-09c37a2c5bbc28b5fbc07a01db4bccdbd0a5d8a2.zip | |
bpf: make skb->tc_classid also readable
Currently, the tc_classid from eBPF skb context is write-only, but there's
no good reason for tc programs to limit it to write-only. For example,
it can be used to transfer its state via tail calls where the resulting
tc_classid gets filled gradually.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
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, 6 insertions, 6 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 6fc3893a6170..69c7b2fecf44 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2069,16 +2069,14 @@ static bool sk_filter_is_valid_access(int off, int size, static bool tc_cls_act_is_valid_access(int off, int size, enum bpf_access_type type) { - if (off == offsetof(struct __sk_buff, tc_classid)) - return type == BPF_WRITE ? true : false; - if (type == BPF_WRITE) { switch (off) { case offsetof(struct __sk_buff, mark): case offsetof(struct __sk_buff, tc_index): case offsetof(struct __sk_buff, priority): case offsetof(struct __sk_buff, cb[0]) ... - offsetof(struct __sk_buff, cb[4]): + offsetof(struct __sk_buff, cb[4]): + case offsetof(struct __sk_buff, tc_classid): break; default: return false; @@ -2195,8 +2193,10 @@ static u32 bpf_net_convert_ctx_access(enum bpf_access_type type, int dst_reg, ctx_off -= offsetof(struct __sk_buff, tc_classid); ctx_off += offsetof(struct sk_buff, cb); ctx_off += offsetof(struct qdisc_skb_cb, tc_classid); - WARN_ON(type != BPF_WRITE); - *insn++ = BPF_STX_MEM(BPF_H, dst_reg, src_reg, ctx_off); + if (type == BPF_WRITE) + *insn++ = BPF_STX_MEM(BPF_H, dst_reg, src_reg, ctx_off); + else + *insn++ = BPF_LDX_MEM(BPF_H, dst_reg, src_reg, ctx_off); break; case offsetof(struct __sk_buff, tc_index): |