On 7/13/22 3:26 AM, Joanne Koong wrote:
In the case where flags is 0, bpf_skb_pull_data and sk_skb_pull_data
should pull the entire skb payload including the bytes in the non-linear
page buffers.
This is documented in the uapi:
"If a zero value is passed for *len*, then the whole length of the *skb*
is pulled"
Fixes: 36bbef52c7eb6 ("bpf: direct packet write and access for helpers
for clsact progs")
Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
This is not correct. We should fix the helper doc fa15601ab31e ("bpf: add
documentation for eBPF helpers (33-41)"). It will make the head private
for writing (e.g. for direct packet access), but not linearize the entire
skb, so skb_headlen is correct here.
---
net/core/filter.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 4ef77ec5255e..97eb15891bfc 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1838,7 +1838,7 @@ BPF_CALL_2(bpf_skb_pull_data, struct sk_buff *, skb, u32, len)
* access case. By this we overcome limitations of only current
* headroom being accessible.
*/
- return bpf_try_make_writable(skb, len ? : skb_headlen(skb));
+ return bpf_try_make_writable(skb, len ? : skb->len);
}
static const struct bpf_func_proto bpf_skb_pull_data_proto = {
@@ -1878,7 +1878,7 @@ BPF_CALL_2(sk_skb_pull_data, struct sk_buff *, skb, u32, len)
* access case. By this we overcome limitations of only current
* headroom being accessible.
*/
- return sk_skb_try_make_writable(skb, len ? : skb_headlen(skb));
+ return sk_skb_try_make_writable(skb, len ? : skb->len);
}
static const struct bpf_func_proto sk_skb_pull_data_proto = {
