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[PATCH v3 1/2] exec: fix up /proc/pid/comm in the execveat(AT_EMPTY_PATH) case

by Tycho Andersen

From: Tycho Andersen <tandersen(a)netflix.com> Zbigniew mentioned at Linux Plumber's that systemd is interested in switching to execveat() for service execution, but can't, because the contents of /proc/pid/comm are the file descriptor which was used, instead of the path to the binary. This makes the output of tools like top and ps useless, especially in a world where most fds are opened CLOEXEC so the number is truly meaningless. Change exec path to fix up /proc/pid/comm in the case where we have allocated one of these synthetic paths in bprm_init(). This way the actual exec machinery is unchanged, but cosmetically the comm looks reasonable to admins investigating things. Signed-off-by: Tycho Andersen <tandersen(a)netflix.com> Suggested-by: Zbigniew Jędrzejewski-Szmek <zbyszek(a)in.waw.pl> CC: Aleksa Sarai <cyphar(a)cyphar.com> Link: https://github.com/uapi-group/kernel-features#set-comm-field-before-exec --- v2: * drop the flag, everyone :) * change the rendered value to f_path.dentry->d_name.name instead of argv[0], Eric v3: * fix up subject line, Eric --- fs/exec.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/fs/exec.c b/fs/exec.c index dad402d55681..9520359a8dcc 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1416,7 +1416,18 @@ int begin_new_exec(struct linux_binprm * bprm) set_dumpable(current->mm, SUID_DUMP_USER); perf_event_exec(); - __set_task_comm(me, kbasename(bprm->filename), true); + + /* + * If fdpath was set, execveat() made up a path that will + * probably not be useful to admins running ps or similar. + * Let's fix it up to be something reasonable. + */ + if (bprm->fdpath) { + BUILD_BUG_ON(TASK_COMM_LEN > DNAME_INLINE_LEN); + __set_task_comm(me, bprm->file->f_path.dentry->d_name.name, true); + } else { + __set_task_comm(me, kbasename(bprm->filename), true); + } /* An exec changes our domain. We are no longer part of the thread group */ base-commit: baeb9a7d8b60b021d907127509c44507539c15e5 -- 2.34.1

9 months

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[PATCH RFC v4 0/9] tun: Introduce virtio-net hashing feature

by Akihiko Odaki

virtio-net have two usage of hashes: one is RSS and another is hash reporting. Conventionally the hash calculation was done by the VMM. However, computing the hash after the queue was chosen defeats the purpose of RSS. Another approach is to use eBPF steering program. This approach has another downside: it cannot report the calculated hash due to the restrictive nature of eBPF. Introduce the code to compute hashes to the kernel in order to overcome thse challenges. An alternative solution is to extend the eBPF steering program so that it will be able to report to the userspace, but it is based on context rewrites, which is in feature freeze. We can adopt kfuncs, but they will not be UAPIs. We opt to ioctl to align with other relevant UAPIs (KVM and vhost_net). The patches for QEMU to use this new feature was submitted as RFC and is available at: https://patchew.org/QEMU/20240915-hash-v3-0-79cb08d28647@daynix.com/ This work was presented at LPC 2024: https://lpc.events/event/18/contributions/1963/ V1 -> V2: Changed to introduce a new BPF program type. Signed-off-by: Akihiko Odaki <akihiko.odaki(a)daynix.com> --- Changes in v4: - Moved tun_vnet_hash_ext to if_tun.h. - Renamed virtio_net_toeplitz() to virtio_net_toeplitz_calc(). - Replaced htons() with cpu_to_be16(). - Changed virtio_net_hash_rss() to return void. - Reordered variable declarations in virtio_net_hash_rss(). - Removed virtio_net_hdr_v1_hash_from_skb(). - Updated messages of "tap: Pad virtio header with zero" and "tun: Pad virtio header with zero". - Fixed vnet_hash allocation size. - Ensured to free vnet_hash when destructing tun_struct. - Link to v3: https://lore.kernel.org/r/20240915-rss-v3-0-c630015db082@daynix.com Changes in v3: - Reverted back to add ioctl. - Split patch "tun: Introduce virtio-net hashing feature" into "tun: Introduce virtio-net hash reporting feature" and "tun: Introduce virtio-net RSS". - Changed to reuse hash values computed for automq instead of performing RSS hashing when hash reporting is requested but RSS is not. - Extracted relevant data from struct tun_struct to keep it minimal. - Added kernel-doc. - Changed to allow calling TUNGETVNETHASHCAP before TUNSETIFF. - Initialized num_buffers with 1. - Added a test case for unclassified packets. - Fixed error handling in tests. - Changed tests to verify that the queue index will not overflow. - Rebased. - Link to v2: https://lore.kernel.org/r/20231015141644.260646-1-akihiko.odaki@daynix.com --- Akihiko Odaki (9): skbuff: Introduce SKB_EXT_TUN_VNET_HASH virtio_net: Add functions for hashing net: flow_dissector: Export flow_keys_dissector_symmetric tap: Pad virtio header with zero tun: Pad virtio header with zero tun: Introduce virtio-net hash reporting feature tun: Introduce virtio-net RSS selftest: tun: Add tests for virtio-net hashing vhost/net: Support VIRTIO_NET_F_HASH_REPORT Documentation/networking/tuntap.rst | 7 + drivers/net/Kconfig | 1 + drivers/net/tap.c | 2 +- drivers/net/tun.c | 255 ++++++++++++-- drivers/vhost/net.c | 16 +- include/linux/if_tun.h | 5 + include/linux/skbuff.h | 3 + include/linux/virtio_net.h | 174 +++++++++ include/net/flow_dissector.h | 1 + include/uapi/linux/if_tun.h | 71 ++++ net/core/flow_dissector.c | 3 +- net/core/skbuff.c | 4 + tools/testing/selftests/net/Makefile | 2 +- tools/testing/selftests/net/tun.c | 666 ++++++++++++++++++++++++++++++++++- 14 files changed, 1170 insertions(+), 40 deletions(-) --- base-commit: 752ebcbe87aceeb6334e846a466116197711a982 change-id: 20240403-rss-e737d89efa77 Best regards, -- Akihiko Odaki <akihiko.odaki(a)daynix.com>

9 months

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[PATCH bpf-next v3 0/2] Support eliding map lookup nullness

by Daniel Xu

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. 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 (2): bpf: verifier: Support eliding map lookup nullness bpf: selftests: verifier: Add nullness elision tests kernel/bpf/verifier.c | 67 ++++++- tools/testing/selftests/bpf/progs/iters.c | 14 +- .../selftests/bpf/progs/map_kptr_fail.c | 2 +- .../bpf/progs/verifier_array_access.c | 166 ++++++++++++++++++ .../selftests/bpf/progs/verifier_map_in_map.c | 2 +- .../testing/selftests/bpf/verifier/map_kptr.c | 2 +- 6 files changed, 242 insertions(+), 11 deletions(-) -- 2.46.0

9 months

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kselftest/fixes build: 6 builds: 2 failed, 4 passed, 1 warning (v6.12-rc1-7-g160c826b4dd0d)

by kernelci.org bot

kselftest/fixes build: 6 builds: 2 failed, 4 passed, 1 warning (v6.12-rc1-7-g160c826b4dd0d) Full Build Summary: https://kernelci.org/build/kselftest/branch/fixes/kernel/v6.12-rc1-7-g160c8… Tree: kselftest Branch: fixes Git Describe: v6.12-rc1-7-g160c826b4dd0d Git Commit: 160c826b4dd0d570f0f51cf002cb49bda807e9f5 Git URL: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git Built: 4 unique architectures Build Failures Detected: arm64: defconfig+kselftest+arm64-chromebook: (clang-16) FAIL defconfig+kselftest+arm64-chromebook: (gcc-12) FAIL Warnings Detected: arm64: arm: i386: x86_64: x86_64_defconfig+kselftest (clang-16): 1 warning Warnings summary: 1 vmlinux.o: warning: objtool: set_ftrace_ops_ro+0x23: relocation to !ENDBR: .text+0x14fd19 ================================================================================ Detailed per-defconfig build reports: -------------------------------------------------------------------------------- defconfig+kselftest+arm64-chromebook (arm64, gcc-12) — FAIL, 0 errors, 0 warnings, 0 section mismatches -------------------------------------------------------------------------------- defconfig+kselftest+arm64-chromebook (arm64, clang-16) — FAIL, 0 errors, 0 warnings, 0 section mismatches -------------------------------------------------------------------------------- i386_defconfig+kselftest (i386, gcc-12) — PASS, 0 errors, 0 warnings, 0 section mismatches -------------------------------------------------------------------------------- multi_v7_defconfig+kselftest (arm, gcc-12) — PASS, 0 errors, 0 warnings, 0 section mismatches -------------------------------------------------------------------------------- x86_64_defconfig+kselftest (x86_64, clang-16) — PASS, 0 errors, 1 warning, 0 section mismatches Warnings: vmlinux.o: warning: objtool: set_ftrace_ops_ro+0x23: relocation to !ENDBR: .text+0x14fd19 -------------------------------------------------------------------------------- x86_64_defconfig+kselftest (x86_64, gcc-12) — PASS, 0 errors, 0 warnings, 0 section mismatches --- For more info write to <info(a)kernelci.org>

9 months

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[PATCH v3 0/2] Exposing nice CPU usage to userspace

by Joshua Hahn

From: Joshua Hahn <joshua.hahn6(a)gmail.com> v2 -> v3: Signed-off-by & renamed subject for clarity. v1 -> v2: Edited commit messages for clarity. Niced CPU usage is a metric reported in host-level /prot/stat, but is not reported in cgroup-level statistics in cpu.stat. However, when a host contains multiple tasks across different workloads, it becomes difficult to gauge how much of the task is being spent on niced processes based on /proc/stat alone, since host-level metrics do not provide this cgroup-level granularity. Exposing this metric will allow users to accurately probe the niced CPU metric for each workload, and make more informed decisions when directing higher priority tasks. Joshua Hahn (2): Tracking cgroup-level niced CPU time Selftests for niced CPU statistics include/linux/cgroup-defs.h | 1 + kernel/cgroup/rstat.c | 16 ++++- tools/testing/selftests/cgroup/test_cpu.c | 72 +++++++++++++++++++++++ 3 files changed, 86 insertions(+), 3 deletions(-) -- 2.43.5

9 months

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[PATCH] KVM: selftests: Fix build on architectures other than x86_64

by Mark Brown

The recent addition of support for testing with the x86 specific quirk KVM_X86_QUIRK_SLOT_ZAP_ALL disabled in the generic memslot tests broke the build of the KVM selftests for all other architectures: In file included from include/kvm_util.h:8, from include/memstress.h:13, from memslot_modification_stress_test.c:21: memslot_modification_stress_test.c: In function ‘main’: memslot_modification_stress_test.c:176:38: error: ‘KVM_X86_QUIRK_SLOT_ZAP_ALL’ undeclared (first use in this function) 176 | KVM_X86_QUIRK_SLOT_ZAP_ALL); | ^~~~~~~~~~~~~~~~~~~~~~~~~~ Add __x86_64__ guard defines to avoid building the relevant code on other architectures. Fixes: 61de4c34b51c ("KVM: selftests: Test memslot move in memslot_perf_test with quirk disabled") Fixes: 218f6415004a ("KVM: selftests: Allow slot modification stress test with quirk disabled") Reported-by: Aishwarya TCV <aishwarya.tcv(a)arm.com> Signed-off-by: Mark Brown <broonie(a)kernel.org> --- This is obviously disruptive for testing of KVM changes on non-x86 architectures. --- tools/testing/selftests/kvm/memslot_modification_stress_test.c | 2 ++ tools/testing/selftests/kvm/memslot_perf_test.c | 6 ++++++ 2 files changed, 8 insertions(+) diff --git a/tools/testing/selftests/kvm/memslot_modification_stress_test.c b/tools/testing/selftests/kvm/memslot_modification_stress_test.c index e3343f0df9e1..c81a84990eab 100644 --- a/tools/testing/selftests/kvm/memslot_modification_stress_test.c +++ b/tools/testing/selftests/kvm/memslot_modification_stress_test.c @@ -169,12 +169,14 @@ int main(int argc, char *argv[]) case 'i': p.nr_iterations = atoi_positive("Number of iterations", optarg); break; +#ifdef __x86_64__ case 'q': p.disable_slot_zap_quirk = true; TEST_REQUIRE(kvm_check_cap(KVM_CAP_DISABLE_QUIRKS2) & KVM_X86_QUIRK_SLOT_ZAP_ALL); break; +#endif case 'h': default: help(argv[0]); diff --git a/tools/testing/selftests/kvm/memslot_perf_test.c b/tools/testing/selftests/kvm/memslot_perf_test.c index 893366982f77..989ffe0d047f 100644 --- a/tools/testing/selftests/kvm/memslot_perf_test.c +++ b/tools/testing/selftests/kvm/memslot_perf_test.c @@ -113,7 +113,9 @@ static_assert(ATOMIC_BOOL_LOCK_FREE == 2, "atomic bool is not lockless"); static sem_t vcpu_ready; static bool map_unmap_verify; +#ifdef __x86_64__ static bool disable_slot_zap_quirk; +#endif static bool verbose; #define pr_info_v(...) \ @@ -579,8 +581,10 @@ static bool test_memslot_move_prepare(struct vm_data *data, uint32_t guest_page_size = data->vm->page_size; uint64_t movesrcgpa, movetestgpa; +#ifdef __x86_64__ if (disable_slot_zap_quirk) vm_enable_cap(data->vm, KVM_CAP_DISABLE_QUIRKS2, KVM_X86_QUIRK_SLOT_ZAP_ALL); +#endif movesrcgpa = vm_slot2gpa(data, data->nslots - 1); @@ -971,11 +975,13 @@ static bool parse_args(int argc, char *argv[], case 'd': map_unmap_verify = true; break; +#ifdef __x86_64__ case 'q': disable_slot_zap_quirk = true; TEST_REQUIRE(kvm_check_cap(KVM_CAP_DISABLE_QUIRKS2) & KVM_X86_QUIRK_SLOT_ZAP_ALL); break; +#endif case 's': targs->nslots = atoi_paranoid(optarg); if (targs->nslots <= 1 && targs->nslots != -1) { --- base-commit: 9852d85ec9d492ebef56dc5f229416c925758edc change-id: 20240930-kvm-build-breakage-a542f46d78f9 Best regards, -- Mark Brown <broonie(a)kernel.org>

9 months

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[PATCH] selftest: hid: add missing run-hid-tools-tests.sh

by Yun Lu

The HID test cases actually run tests using the run-hid-tools-tests.sh script. However, if installed with "make install", the run-hid-tools-tests.sh script will not be copied over, resulting in the following error message. make -C tools/testing/selftests/ TARGETS=hid install \ INSTALL_PATH=$KSFT_INSTALL_PATH cd $KSFT_INSTALL_PATH ./run_kselftest.sh -c hid selftests: hid: hid-core.sh bash: ./run-hid-tools-tests.sh: No such file or directory So add the run-hid-tools-tests.sh script to the TEST_FILES in the Makefile. Signed-off-by: Yun Lu <luyun(a)kylinos.cn> --- tools/testing/selftests/hid/Makefile | 2 ++ 1 file changed, 2 insertions(+) diff --git a/tools/testing/selftests/hid/Makefile b/tools/testing/selftests/hid/Makefile index 72be55ac4bdf..38ae31bb07b5 100644 --- a/tools/testing/selftests/hid/Makefile +++ b/tools/testing/selftests/hid/Makefile @@ -17,6 +17,8 @@ TEST_PROGS += hid-tablet.sh TEST_PROGS += hid-usb_crash.sh TEST_PROGS += hid-wacom.sh +TEST_FILES := run-hid-tools-tests.sh + CXX ?= $(CROSS_COMPILE)g++ HOSTPKG_CONFIG := pkg-config -- 2.27.0

9 months

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[PATCH] selftests: vDSO: align getrandom states to cache line

by Jason A. Donenfeld

This prevents false sharing, which makes a large difference on machines with several NUMA nodes, such as on a dual socket Intel(R) Xeon(R) Gold 6338 CPU @ 2.00GHz, where the "bench-multi" test goes from 2.7s down to 1.9s. While this is just test code, it also forms the basis of how folks will wind up implementing this in libraries, so we should implement this simple cache alignment improvement here. Suggested-by: Florian Weimer <fweimer(a)redhat.com> Cc: Adhemerval Zanella <adhemerval.zanella(a)linaro.org> Signed-off-by: Jason A. Donenfeld <Jason(a)zx2c4.com> --- tools/testing/selftests/vDSO/vdso_test_getrandom.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/vDSO/vdso_test_getrandom.c b/tools/testing/selftests/vDSO/vdso_test_getrandom.c index 72a1d9b43a84..e5e83dbec589 100644 --- a/tools/testing/selftests/vDSO/vdso_test_getrandom.c +++ b/tools/testing/selftests/vDSO/vdso_test_getrandom.c @@ -59,10 +59,12 @@ static void *vgetrandom_get_state(void) size_t page_size = getpagesize(); size_t new_cap; size_t alloc_size, num = sysconf(_SC_NPROCESSORS_ONLN); /* Just a decent heuristic. */ + size_t state_size_aligned, cache_line_size = sysconf(_SC_LEVEL1_DCACHE_LINESIZE) ?: 1; void *new_block, *new_states; - alloc_size = (num * vgrnd.params.size_of_opaque_state + page_size - 1) & (~(page_size - 1)); - num = (page_size / vgrnd.params.size_of_opaque_state) * (alloc_size / page_size); + state_size_aligned = (vgrnd.params.size_of_opaque_state + cache_line_size - 1) & (~(cache_line_size - 1)); + alloc_size = (num * state_size_aligned + page_size - 1) & (~(page_size - 1)); + num = (page_size / state_size_aligned) * (alloc_size / page_size); new_block = mmap(0, alloc_size, vgrnd.params.mmap_prot, vgrnd.params.mmap_flags, -1, 0); if (new_block == MAP_FAILED) goto out; @@ -78,7 +80,7 @@ static void *vgetrandom_get_state(void) if (((uintptr_t)new_block & (page_size - 1)) + vgrnd.params.size_of_opaque_state > page_size) new_block = (void *)(((uintptr_t)new_block + page_size - 1) & (~(page_size - 1))); vgrnd.states[i] = new_block; - new_block += vgrnd.params.size_of_opaque_state; + new_block += state_size_aligned; } vgrnd.len = num; goto success; -- 2.46.0

9 months

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[RFC PATCH 0/3] introduce PIDFD_SELF

by Lorenzo Stoakes

If you wish to utilise a pidfd interface to refer to the current process (from the point of view of userland - from the kernel point of view - the thread group leader), it is rather cumbersome, requiring something like: int pidfd = pidfd_open(getpid(), 0); ... close(pidfd); Or the equivalent call opening /proc/self. It is more convenient to use a sentinel value to indicate to an interface that accepts a pidfd that we simply wish to refer to the current process. This series introduces such a sentinel, PIDFD_SELF, which can be passed as the pidfd in this instance rather than having to establish a dummy fd for this purpose. The only pidfd interface where this is particularly useful is process_madvise(), which provides the motivation for this series. However, as this is a general interface, we ensure that all pidfd interfaces can handle this correctly. We ensure that pidfd_send_signal() and pidfd_getfd() work correctly, and assert as much in selftests. All other interfaces except setns() will work implicitly with this new interface, however it doesn't make sense to test waitid(P_PIDFD, ...) as waiting on ourselves is a blocking operation. In the case of setns() we explicitly disallow use of PIDFD_SELF as it doesn't make sense to obtain the namespaces of our own process, and it would require work to implement this functionality there that would be of no use. We also do not provide the ability to utilise PIDFD_SELF in ordinary fd operations such as open() or poll(), as this would require extensive work and be of no real use. Lorenzo Stoakes (3): pidfd: refactor pidfd_get_pid/to_pid() and de-duplicate pid lookup pidfd: add PIDFD_SELF sentinel to refer to own process selftests: pidfd: add tests for PIDFD_SELF include/linux/pid.h | 43 +++++++++++- include/uapi/linux/pidfd.h | 3 + kernel/exit.c | 3 +- kernel/nsproxy.c | 1 + kernel/pid.c | 70 +++++++++++++------ kernel/signal.c | 26 ++----- tools/testing/selftests/pidfd/pidfd.h | 5 ++ .../selftests/pidfd/pidfd_getfd_test.c | 38 ++++++++++ .../selftests/pidfd/pidfd_setns_test.c | 6 ++ tools/testing/selftests/pidfd/pidfd_test.c | 13 ++++ 10 files changed, 165 insertions(+), 43 deletions(-) -- 2.46.2

9 months

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Re: [PATCH v2 1/2] exec: add a flag for "reasonable" execveat() comm

by Eric W. Biederman

"Eric W. Biederman" <ebiederm(a)xmission.com> writes: > Kees Cook <kees(a)kernel.org> writes: >> I'm not super comfortable doing this regardless of bprm->fdpath; that >> seems like too many cases getting changed. Can we just leave it as >> depending on bprm->fdpath? I was recommending that because I did not expect that there was any widespread usage of aliasing of binary names using symlinks. I realized today that on debian there are many aliases of binaries created with the /etc/alternatives mechanism. So there is much wider exposure to problems than I would have supposed. So I remove any objections to making the new code conditional on bprm->fdpath. Eric

9 months

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