On Mon, Nov 6, 2023 at 4:16 PM David Ahern dsahern@kernel.org wrote:
On 11/5/23 7:44 PM, Mina Almasry wrote:
diff --git a/net/core/datagram.c b/net/core/datagram.c index 176eb5834746..cdd4fb129968 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -425,6 +425,9 @@ static int __skb_datagram_iter(const struct sk_buff *skb, int offset, return 0; }
if (skb_frags_not_readable(skb))goto short_copy;/* Copy paged appendix. Hmm... why does this look so complicated? */ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { int end;@@ -616,6 +619,9 @@ int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk, { int frag;
if (skb_frags_not_readable(skb))return -EFAULT;This check ....
if (msg && msg->msg_ubuf && msg->sg_from_iter) return msg->sg_from_iter(sk, skb, from, length);... should go here. That allows custome sg_from_iter to have access to the skb. What matters is not expecting struct page (e.g., refcounting); if the custom iter does not do that then all is well. io_uring's iter does not look at the pages, so all good.
diff --git a/net/core/gro.c b/net/core/gro.c index 42d7f6755f32..56046d65386a 100644 --- a/net/core/gro.c +++ b/net/core/gro.c @@ -390,6 +390,9 @@ static void gro_pull_from_frag0(struct sk_buff *skb, int grow) { struct skb_shared_info *pinfo = skb_shinfo(skb);
if (WARN_ON_ONCE(skb_frags_not_readable(skb)))return;BUG_ON(skb->end - skb->tail < grow); memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);@@ -411,7 +414,7 @@ static void gro_try_pull_from_frag0(struct sk_buff *skb) { int grow = skb_gro_offset(skb) - skb_headlen(skb);
if (grow > 0)
if (grow > 0 && !skb_frags_not_readable(skb)) gro_pull_from_frag0(skb, grow);}
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 13eca4fd25e1..f01673ed2eff 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1230,6 +1230,14 @@ void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt) struct page *p; u8 *vaddr;
if (skb_frag_is_page_pool_iov(frag)) {Why skb_frag_is_page_pool_iov here vs skb_frags_not_readable?
Seems like a silly choice on my end. I should probably check skb_frags_not_readable() and not kmap any frags in that case. Will do.