[rlc-8/4.18.0-553.123.1.el8_10] xfrm: esp: avoid in-place decrypt on shared skb frags#1198
Merged
shreeya-patel98 merged 1 commit intoMay 8, 2026
Conversation
unpub-cve DIRTY-FRAG commit-author Kuan-Ting Chen <h3xrabbit@gmail.com> commit f4c50a4 upstream-diff | While this kernel lacks MSG_SPLICE_PAGES, it still has udp_sendpage(). Upstream didn't patch udp_sendpage() because sendpage was removed entirely in favor of MSG_SPLICE_PAGES. In this kernel, splice() can still attach a page cache page to an IPv4 datagram via sendpage. Therefore, udp_sendpage() must be patched instead. And there is no patch for IPv6 datagrams because it isn't affected; there's no sendpage callback for IPv6 UDP. Due to missing 06b4feb ("net: group skb_shinfo zerocopy related bits together.") SKBFL_SHARED_FRAG was replaced with SKBTX_SHARED_FRAG. Also replaced flags with tx_flags. MSG_SPLICE_PAGES can attach pages from a pipe directly to an skb. TCP marks such skbs with SKBFL_SHARED_FRAG after skb_splice_from_iter(), so later paths that may modify packet data can first make a private copy. The IPv4/IPv6 datagram append paths did not set this flag when splicing pages into UDP skbs. That leaves an ESP-in-UDP packet made from shared pipe pages looking like an ordinary uncloned nonlinear skb. ESP input then takes the no-COW fast path for uncloned skbs without a frag_list and decrypts in place over data that is not owned privately by the skb. Mark IPv4/IPv6 datagram splice frags with SKBFL_SHARED_FRAG, matching TCP. Also make ESP input fall back to skb_cow_data() when the flag is present, so ESP does not decrypt externally backed frags in place. Private nonlinear skb frags still use the existing fast path. This intentionally does not change ESP output. In esp_output_head(), the path that appends the ESP trailer to existing skb tailroom without calling skb_cow_data() is not reachable for nonlinear skbs: skb_tailroom() returns zero when skb->data_len is nonzero, while ESP tailen is positive. Thus ESP output will either use the separate destination-frag path or fall back to skb_cow_data(). Fixes: cac2661 ("esp4: Avoid skb_cow_data whenever possible") Fixes: 03e2a30 ("esp6: Avoid skb_cow_data whenever possible") Fixes: 7da0dde ("ip, udp: Support MSG_SPLICE_PAGES") Fixes: 6d8192b ("ip6, udp6: Support MSG_SPLICE_PAGES") Reported-by: Hyunwoo Kim <imv4bel@gmail.com> Reported-by: Kuan-Ting Chen <h3xrabbit@gmail.com> Tested-by: Hyunwoo Kim <imv4bel@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Kuan-Ting Chen <h3xrabbit@gmail.com> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com> (cherry picked from commit f4c50a4) Signed-off-by: Shreeya Patel <spatel@ciq.com> Signed-off-by: Roxana Nicolescu <rnicolescu@ciq.com>
ciq-kernel-automation
Bot
added
the
created-by-kernelci
|
🤖 Validation Checks In Progress Workflow run: https://github.com/ctrliq/kernel-src-tree/actions/runs/25554978388 |
🔍 Upstream Linux Kernel Commit Check
This is an automated message from the kernel commit checker workflow. |
🔍 Interdiff Analysis
================================================================================
* DELTA DIFFERENCES - code changes that differ between the patches *
================================================================================
--- b/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1347,9 +1347,6 @@
goto error;
}
- if (!(flags & MSG_NO_SHARED_FRAGS))
- skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
-
if (skb->ip_summed == CHECKSUM_NONE) {
__wsum csum;
csum = csum_page(page, offset, len);
################################################################################
! REJECTED PATCH2 HUNKS - could not be compared; manual review needed !
################################################################################
--- b/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1233,6 +1233,8 @@
if (err < 0)
goto error;
copy = err;
+ if (!(flags & MSG_NO_SHARED_FRAGS))
+ skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
wmem_alloc_delta += copy;
} else if (!zc) {
int i = skb_shinfo(skb)->nr_frags;
================================================================================
* CONTEXT DIFFERENCES - surrounding code differences between the patches *
================================================================================
--- b/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1230,6 +1230,6 @@
- goto error;
- }
-
- if (skb->ip_summed == CHECKSUM_NONE) {
- __wsum csum;
- csum = csum_page(page, offset, len);
+ if (err < 0)
+ goto error;
+ copy = err;
+ wmem_alloc_delta += copy;
+ } else if (!zc) {
+ int i = skb_shinfo(skb)->nr_frags;
================================================================================
* ONLY IN PATCH2 - files not modified by patch1 *
================================================================================
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -915,7 +915,8 @@ static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
nfrags = 1;
goto skip_cow;
- } else if (!skb_has_frag_list(skb)) {
+ } else if (!skb_has_frag_list(skb) &&
+ !skb_has_shared_frag(skb)) {
nfrags = skb_shinfo(skb)->nr_frags;
nfrags++;
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1794,6 +1794,8 @@ alloc_new_skb:
if (err < 0)
goto error;
copy = err;
+ if (!(flags & MSG_NO_SHARED_FRAGS))
+ skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
wmem_alloc_delta += copy;
} else if (!zc) {
int i = skb_shinfo(skb)->nr_frags;This is an automated interdiff check for backported commits. |
|
✅ Validation checks completed successfully View full results: https://github.com/ctrliq/kernel-src-tree/actions/runs/25554978388 |
|
Maybe a dumb question, but is there a reason we're not also patching net/ipv6/ as well as net/ipv4? |
Collaborator
@jdieter that's a very good question. I don't think we have checked if ipv6 is affected or not. I'll have a look at it. |
shreeya-patel98
approved these changes
May 8, 2026
shreeya-patel98
merged commit f933b95
into
rlc-8/4.18.0-553.123.1.el8_10
4 checks passed
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Local test
Summary
This PR has been automatically created after successful completion of all CI stages.
Commit Message(s)
Test Results
✅ Build Stage
✅ Boot Verification
✅ Kernel Selftests
✅ LTP Results
🤖 This PR was automatically generated by GitHub Actions
Run ID: 25546132093