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| author | Willem de Bruijn <willemb@google.com> | 2020-03-03 15:05:01 -0500 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-03-03 16:23:59 -0800 |
| commit | cf62089b0edd7e74a1f474844b4d9f7b5697fb5c (patch) | |
| tree | 9daf8bfb7c74ff98ca4c507f8d5bf8184c4d7bec | |
| parent | abbc61a5f26d52a5d3abbbe552b275360b2c6631 (diff) | |
| download | linux-next-cf62089b0edd7e74a1f474844b4d9f7b5697fb5c.tar.gz | |
bpf: Add gso_size to __sk_buff
BPF programs may want to know whether an skb is gso. The canonical
answer is skb_is_gso(skb), which tests that gso_size != 0.
Expose this field in the same manner as gso_segs. That field itself
is not a sufficient signal, as the comment in skb_shared_info makes
clear: gso_segs may be zero, e.g., from dodgy sources.
Also prepare net/bpf/test_run for upcoming BPF_PROG_TEST_RUN tests
of the feature.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200303200503.226217-2-willemdebruijn.kernel@gmail.com
| -rw-r--r-- | include/uapi/linux/bpf.h | 1 | ||||
| -rw-r--r-- | net/bpf/test_run.c | 7 | ||||
| -rw-r--r-- | net/core/filter.c | 44 |
3 files changed, 38 insertions, 14 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 8e98ced0963b..180337fae97e 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3176,6 +3176,7 @@ struct __sk_buff { __u32 wire_len; __u32 gso_segs; __bpf_md_ptr(struct bpf_sock *, sk); + __u32 gso_size; }; struct bpf_tunnel_key { diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 562443f94133..1cd7a1c2f8b2 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -277,6 +277,12 @@ static int convert___skb_to_skb(struct sk_buff *skb, struct __sk_buff *__skb) /* gso_segs is allowed */ if (!range_is_zero(__skb, offsetofend(struct __sk_buff, gso_segs), + offsetof(struct __sk_buff, gso_size))) + return -EINVAL; + + /* gso_size is allowed */ + + if (!range_is_zero(__skb, offsetofend(struct __sk_buff, gso_size), sizeof(struct __sk_buff))) return -EINVAL; @@ -297,6 +303,7 @@ static int convert___skb_to_skb(struct sk_buff *skb, struct __sk_buff *__skb) if (__skb->gso_segs > GSO_MAX_SEGS) return -EINVAL; skb_shinfo(skb)->gso_segs = __skb->gso_segs; + skb_shinfo(skb)->gso_size = __skb->gso_size; return 0; } diff --git a/net/core/filter.c b/net/core/filter.c index 4a08c9fb2be7..cd0a532db4e7 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7139,6 +7139,27 @@ static u32 flow_dissector_convert_ctx_access(enum bpf_access_type type, return insn - insn_buf; } +static struct bpf_insn *bpf_convert_shinfo_access(const struct bpf_insn *si, + struct bpf_insn *insn) +{ + /* si->dst_reg = skb_shinfo(SKB); */ +#ifdef NET_SKBUFF_DATA_USES_OFFSET + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, end), + BPF_REG_AX, si->src_reg, + offsetof(struct sk_buff, end)); + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, head), + si->dst_reg, si->src_reg, + offsetof(struct sk_buff, head)); + *insn++ = BPF_ALU64_REG(BPF_ADD, si->dst_reg, BPF_REG_AX); +#else + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, end), + si->dst_reg, si->src_reg, + offsetof(struct sk_buff, end)); +#endif + + return insn; +} + static u32 bpf_convert_ctx_access(enum bpf_access_type type, const struct bpf_insn *si, struct bpf_insn *insn_buf, @@ -7461,26 +7482,21 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type, break; case offsetof(struct __sk_buff, gso_segs): - /* si->dst_reg = skb_shinfo(SKB); */ -#ifdef NET_SKBUFF_DATA_USES_OFFSET - *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, end), - BPF_REG_AX, si->src_reg, - offsetof(struct sk_buff, end)); - *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, head), - si->dst_reg, si->src_reg, - offsetof(struct sk_buff, head)); - *insn++ = BPF_ALU64_REG(BPF_ADD, si->dst_reg, BPF_REG_AX); -#else - *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, end), - si->dst_reg, si->src_reg, - offsetof(struct sk_buff, end)); -#endif + insn = bpf_convert_shinfo_access(si, insn); *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct skb_shared_info, gso_segs), si->dst_reg, si->dst_reg, bpf_target_off(struct skb_shared_info, gso_segs, 2, target_size)); break; + case offsetof(struct __sk_buff, gso_size): + insn = bpf_convert_shinfo_access(si, insn); + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct skb_shared_info, gso_size), + si->dst_reg, si->dst_reg, + bpf_target_off(struct skb_shared_info, + gso_size, 2, + target_size)); + break; case offsetof(struct __sk_buff, wire_len): BUILD_BUG_ON(sizeof_field(struct qdisc_skb_cb, pkt_len) != 4); |