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authorWillem de Bruijn <willemb@google.com>2020-03-03 23:05:01 +0300
committerAlexei Starovoitov <ast@kernel.org>2020-03-04 03:23:59 +0300
commitcf62089b0edd7e74a1f474844b4d9f7b5697fb5c (patch)
tree9daf8bfb7c74ff98ca4c507f8d5bf8184c4d7bec
parentabbc61a5f26d52a5d3abbbe552b275360b2c6631 (diff)
downloadlinux-cf62089b0edd7e74a1f474844b4d9f7b5697fb5c.tar.xz
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.h1
-rw-r--r--net/bpf/test_run.c7
-rw-r--r--net/core/filter.c44
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);