Commit 4094871db1d6 ("udp: only do GSO if # of segs > 1") avoided GSO
for small packets. But the kernel currently dismisses GSO requests only
after checking MTU/PMTU on gso_size. This means any packets, regardless
of their payload sizes, could be dropped when PMTU becomes smaller than
requested gso_size. We encountered this issue in production and it
caused a reliability problem that new QUIC connection cannot be
established before PMTU cache expired, while non GSO sockets still
worked fine at the same time.
Ideally, do not check any GSO related constraints when payload size is
smaller than requested gso_size, and return EMSGSIZE instead of EINVAL
on MTU/PMTU check failure to be more specific on the error cause.
Fixes: 4094871db1d6 ("udp: only do GSO if # of segs > 1")
Signed-off-by: Yan Zhai <yan(a)cloudflare.com>
Suggested-by: Willem de Bruijn <willemdebruijn.kernel(a)gmail.com>
---
v2->v3: simplify the code; adding two test cases
v1->v2: add a missing MTU check when fall back to no GSO mode; Fixed up
commit message to be more precise.
v2: https://lore.kernel.org/netdev/Z5swit7ykNRbJFMS@debian.debian/T/#u
v1: https://lore.kernel.org/all/Z5cgWh%2F6bRQm9vVU@debian.debian/
---
net/ipv4/udp.c | 4 ++--
net/ipv6/udp.c | 4 ++--
tools/testing/selftests/net/udpgso.c | 26 ++++++++++++++++++++++++++
3 files changed, 30 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index c472c9a57cf6..a9bb9ce5438e 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1141,9 +1141,9 @@ static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4,
const int hlen = skb_network_header_len(skb) +
sizeof(struct udphdr);
- if (hlen + cork->gso_size > cork->fragsize) {
+ if (hlen + min(datalen, cork->gso_size) > cork->fragsize) {
kfree_skb(skb);
- return -EINVAL;
+ return -EMSGSIZE;
}
if (datalen > cork->gso_size * UDP_MAX_SEGMENTS) {
kfree_skb(skb);
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 6671daa67f4f..c6ea438b5c75 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1389,9 +1389,9 @@ static int udp_v6_send_skb(struct sk_buff *skb, struct flowi6 *fl6,
const int hlen = skb_network_header_len(skb) +
sizeof(struct udphdr);
- if (hlen + cork->gso_size > cork->fragsize) {
+ if (hlen + min(datalen, cork->gso_size) > cork->fragsize) {
kfree_skb(skb);
- return -EINVAL;
+ return -EMSGSIZE;
}
if (datalen > cork->gso_size * UDP_MAX_SEGMENTS) {
kfree_skb(skb);
diff --git a/tools/testing/selftests/net/udpgso.c b/tools/testing/selftests/net/udpgso.c
index 3f2fca02fec5..36ff28af4b19 100644
--- a/tools/testing/selftests/net/udpgso.c
+++ b/tools/testing/selftests/net/udpgso.c
@@ -102,6 +102,19 @@ struct testcase testcases_v4[] = {
.gso_len = CONST_MSS_V4,
.r_num_mss = 1,
},
+ {
+ /* datalen <= MSS < gso_len: will fall back to no GSO */
+ .tlen = CONST_MSS_V4,
+ .gso_len = CONST_MSS_V4 + 1,
+ .r_num_mss = 0,
+ .r_len_last = CONST_MSS_V4,
+ },
+ {
+ /* MSS < datalen < gso_len: fail */
+ .tlen = CONST_MSS_V4 + 1,
+ .gso_len = CONST_MSS_V4 + 2,
+ .tfail = true,
+ },
{
/* send a single MSS + 1B */
.tlen = CONST_MSS_V4 + 1,
@@ -205,6 +218,19 @@ struct testcase testcases_v6[] = {
.gso_len = CONST_MSS_V6,
.r_num_mss = 1,
},
+ {
+ /* datalen <= MSS < gso_len: will fall back to no GSO */
+ .tlen = CONST_MSS_V6,
+ .gso_len = CONST_MSS_V6 + 1,
+ .r_num_mss = 0,
+ .r_len_last = CONST_MSS_V6,
+ },
+ {
+ /* MSS < datalen < gso_len: fail */
+ .tlen = CONST_MSS_V6 + 1,
+ .gso_len = CONST_MSS_V6 + 2,
+ .tfail = true
+ },
{
/* send a single MSS + 1B */
.tlen = CONST_MSS_V6 + 1,
--
2.30.2
After submitting the patch implementing the SO_RCVPRIORITY socket option
(https://lore.kernel.org/netdev/20241213084457.45120-5-annaemesenyiri@gmail.…),
it was requested to include a test for the functionality. As a first step, write
a test that also validates the SO_RCVMARK value, since no existing test covers
it. If this combined test is not suitable, I will provide a standalone
test specifically for SO_RCVPRIORITY and submit it separately.
Anna Emese Nyiri (1):
add support for testing SO_RCVMARK and SO_RCVPRIORITY
tools/testing/selftests/net/Makefile | 1 +
tools/testing/selftests/net/so_rcv_listener.c | 147 ++++++++++++++++++
tools/testing/selftests/net/test_so_rcv.sh | 56 +++++++
3 files changed, 204 insertions(+)
create mode 100644 tools/testing/selftests/net/so_rcv_listener.c
create mode 100755 tools/testing/selftests/net/test_so_rcv.sh
--
2.43.0
This patch allows progs to elide a null check on statically known map
lookup keys. In other words, if the verifier can statically prove that
the lookup will be in-bounds, allow the prog to drop the null check.
This is useful for two reasons:
1. Large numbers of nullness checks (especially when they cannot fail)
unnecessarily pushes prog towards BPF_COMPLEXITY_LIMIT_JMP_SEQ.
2. It forms a tighter contract between programmer and verifier.
For (1), bpftrace is starting to make heavier use of percpu scratch
maps. As a result, for user scripts with large number of unrolled loops,
we are starting to hit jump complexity verification errors. These
percpu lookups cannot fail anyways, as we only use static key values.
Eliding nullness probably results in less work for verifier as well.
For (2), percpu scratch maps are often used as a larger stack, as the
currrent stack is limited to 512 bytes. In these situations, it is
desirable for the programmer to express: "this lookup should never fail,
and if it does, it means I messed up the code". By omitting the null
check, the programmer can "ask" the verifier to double check the logic.
=== Changelog ===
Changes in v7:
* Use more accurate frame number when marking precise
* Add test for non-stack key
* Test for marking stack slot precise
Changes in v6:
* Use is_spilled_scalar_reg() helper and remove unnecessary comment
* Add back deleted selftest with different helper to dirty dst buffer
* Check size of spill is exactly key_size and update selftests
* Read slot_type from correct offset into the spi
* Rewrite selftests in C where possible
* Mark constant map keys as precise
Changes in v5:
* Dropped all acks
* Use s64 instead of long for const_map_key
* Ensure stack slot contains spilled reg before accessing spilled_ptr
* Ensure spilled reg is a scalar before accessing tnum const value
* Fix verifier selftest for 32-bit write to write at 8 byte alignment
to ensure spill is tracked
* Introduce more precise tracking of helper stack accesses
* Do constant map key extraction as part of helper argument processing
and then remove duplicated stack checks
* Use ret_flag instead of regs[BPF_REG_0].type
* Handle STACK_ZERO
* Fix bug in bpf_load_hdr_opt() arg annotation
Changes in v4:
* Only allow for CAP_BPF
* Add test for stack growing upwards
* Improve comment about stack growing upwards
Changes in v3:
* Check if stack is (erroneously) growing upwards
* Mention in commit message why existing tests needed change
Changes in v2:
* Added a check for when R2 is not a ptr to stack
* Added a check for when stack is uninitialized (no stack slot yet)
* Updated existing tests to account for null elision
* Added test case for when R2 can be both const and non-const
Daniel Xu (5):
bpf: verifier: Add missing newline on verbose() call
bpf: tcp: Mark bpf_load_hdr_opt() arg2 as read-write
bpf: verifier: Refactor helper access type tracking
bpf: verifier: Support eliding map lookup nullness
bpf: selftests: verifier: Add nullness elision tests
kernel/bpf/verifier.c | 139 ++++++++++---
net/core/filter.c | 2 +-
.../testing/selftests/bpf/progs/dynptr_fail.c | 6 +-
tools/testing/selftests/bpf/progs/iters.c | 14 +-
.../selftests/bpf/progs/map_kptr_fail.c | 2 +-
.../selftests/bpf/progs/test_global_func10.c | 2 +-
.../selftests/bpf/progs/uninit_stack.c | 5 +-
.../bpf/progs/verifier_array_access.c | 188 ++++++++++++++++++
.../bpf/progs/verifier_basic_stack.c | 2 +-
.../selftests/bpf/progs/verifier_const_or.c | 4 +-
.../progs/verifier_helper_access_var_len.c | 12 +-
.../selftests/bpf/progs/verifier_int_ptr.c | 2 +-
.../selftests/bpf/progs/verifier_map_in_map.c | 2 +-
.../selftests/bpf/progs/verifier_mtu.c | 2 +-
.../selftests/bpf/progs/verifier_raw_stack.c | 4 +-
.../selftests/bpf/progs/verifier_unpriv.c | 2 +-
.../selftests/bpf/progs/verifier_var_off.c | 8 +-
tools/testing/selftests/bpf/verifier/calls.c | 2 +-
.../testing/selftests/bpf/verifier/map_kptr.c | 2 +-
19 files changed, 331 insertions(+), 69 deletions(-)
--
2.47.1
Fix the build failure caused by the undefined `CLONE_NEWTIME`.
Include the `linux/sched.h` header file where the function is defined to
ensure successful compilation of the selftests.
Signed-off-by: Purva Yeshi <purvayeshi550(a)gmail.com>
---
tools/testing/selftests/vDSO/vdso_test_getrandom.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/tools/testing/selftests/vDSO/vdso_test_getrandom.c b/tools/testing/selftests/vDSO/vdso_test_getrandom.c
index 95057f7567db..b2c9cf15878b 100644
--- a/tools/testing/selftests/vDSO/vdso_test_getrandom.c
+++ b/tools/testing/selftests/vDSO/vdso_test_getrandom.c
@@ -29,6 +29,8 @@
#include "vdso_config.h"
#include "vdso_call.h"
+#include <linux/sched.h>
+
#ifndef timespecsub
#define timespecsub(tsp, usp, vsp) \
do { \
--
2.34.1
A few cleanups and optimizations for the management of the kernel
configuration.
Signed-off-by: Thomas Weißschuh <linux(a)weissschuh.net>
---
Changes in v2:
- Rebase on current torvalds/master
- Call "make defconfig" separately
- Link to v1: https://lore.kernel.org/r/20250122-nolibc-config-v1-0-a697db968b49@weisssch…
---
Thomas Weißschuh (5):
selftests/nolibc: drop custom EXTRACONFIG functionality
selftests/nolibc: drop call to prepare target
selftests/nolibc: drop call to mrproper target
selftests/nolibc: execute defconfig before other targets
selftests/nolibc: always keep test kernel configuration up to date
tools/testing/selftests/nolibc/Makefile | 17 +++++------------
tools/testing/selftests/nolibc/run-tests.sh | 7 +++----
2 files changed, 8 insertions(+), 16 deletions(-)
---
base-commit: 21266b8df5224c4f677acf9f353eecc9094731f0
change-id: 20250122-nolibc-config-d639e1612c93
Best regards,
--
Thomas Weißschuh <linux(a)weissschuh.net>