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[PATCHv2 net 1/2] bonding: set random address only when slaves already exist

by Hangbin Liu

After commit 5c3bf6cba791 ("bonding: assign random address if device address is same as bond"), bonding will erroneously randomize the MAC address of the first interface added to the bond if fail_over_mac = follow. Correct this by additionally testing for the bond being empty before randomizing the MAC. Fixes: 5c3bf6cba791 ("bonding: assign random address if device address is same as bond") Reported-by: Qiuling Ren <qren(a)redhat.com> Signed-off-by: Hangbin Liu <liuhangbin(a)gmail.com> --- drivers/net/bonding/bond_main.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 257333c88710..8832bc9f107b 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2132,6 +2132,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev, memcpy(ss.__data, bond_dev->dev_addr, bond_dev->addr_len); } else if (bond->params.fail_over_mac == BOND_FOM_FOLLOW && BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP && + bond_has_slaves(bond) && memcmp(slave_dev->dev_addr, bond_dev->dev_addr, bond_dev->addr_len) == 0) { /* Set slave to random address to avoid duplicate mac * address in later fail over. -- 2.50.1

3 months

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[PATCH] KVM: selftests: Fix typo in hyperv cpuid test message

by Alok Tiwari

Fix a typo in hyperv_cpuid.c test assertion log: replace "our of supported range" -> "out of supported range". Signed-off-by: Alok Tiwari <alok.a.tiwari(a)oracle.com> --- tools/testing/selftests/kvm/x86/hyperv_cpuid.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/kvm/x86/hyperv_cpuid.c b/tools/testing/selftests/kvm/x86/hyperv_cpuid.c index c863a689aa985..3c21af811d8f1 100644 --- a/tools/testing/selftests/kvm/x86/hyperv_cpuid.c +++ b/tools/testing/selftests/kvm/x86/hyperv_cpuid.c @@ -45,7 +45,7 @@ static void test_hv_cpuid(struct kvm_vcpu *vcpu, bool evmcs_expected) TEST_ASSERT((entry->function >= 0x40000000) && (entry->function <= 0x40000082), - "function %x is our of supported range", + "function %x is out of supported range", entry->function); TEST_ASSERT(entry->index == 0, -- 2.50.1

3 months

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[PATCH v18 net-next 00/14] AccECN protocol patch series

by chia-yu.chang＠nokia-bell-labs.com

From: Chia-Yu Chang <chia-yu.chang(a)nokia-bell-labs.com> Hello, Please find the v18 AccECN protocol patch series, which covers the core functionality of Accurate ECN, AccECN negotiation, AccECN TCP options, and AccECN failure handling. The Accurate ECN draft can be found in https://datatracker.ietf.org/doc/html/draft-ietf-tcpm-accurate-ecn-28, and it will be RFC9768. This patch series is part of the full AccECN patch series, which is available at https://github.com/L4STeam/linux-net-next/commits/upstream_l4steam/ Best Regards, Chia-Yu --- v18 (11-Sep-2025) - Reorder tcpi_accecn_fail_mode and tcpi_accecn_opt_seen to avoid adding fields in the middle of tcp_info (Eric Dumazet <edumazet(a)google.com>) v17 (8-Sep-2025) - Change tcp_ecn_mode_max from 5 to 2 to disable AccECN enablement before the whole AccECN feature been accpeted v16 (6-Sep-2025) - Use TCP_ECN_IN_ACCECN_OUT_ACCECN, TCP_ECN_IN_ECN_OUT_ECN, and TCP_ECN_IN_ACCECN_OUT_ECN in comments of tcp_ecn_send_syn() (Eric Dumazet <edumazet(a)google.com>) - Add tcpi_accecn_fail_mode and tcpi_accecn_opt_seen to make tcp_info be multiple of 64 bits in patch #12 v15 (14-Aug-205) - Update pahole results in commit messages - Accurate ECN will become RFC9768 v14 (22-Jul-2025) - Add missing const for struct tcp_sock of tcp_accecn_option_beacon_check() of #11 (Simon Horman <horms(a)kernel.org>) v13 (18-Jul-2025) - Implement tcp_accecn_extract_syn_ect() and tcp_accecn_reflector_flags() with static array lookup of patch #6 (Paolo Abeni <pabeni(a)redhat.com>) - Fix typos in comments of #6 and remove patch #7 of v12 about simulatenous connect (Paolo Abeni <pabeni(a)redhat.com>) - Move TCP_ACCECN_E1B_INIT_OFFSET, TCP_ACCECN_E0B_INIT_OFFSET, and TCP_ACCECN_CEB_INIT_OFFSET from patch #7 to #11 (Paolo Abeni <pabeni(a)redhat.com>) - Use static array lookup in tcp_accecn_optfield_to_ecnfield() of patch #11 (Paolo Abeni <pabeni(a)redhat.com>) - Return false when WARN_ON_ONCE() is true in tcp_accecn_process_option() of patch #11 (Paolo Abeni <pabeni(a)redhat.com>) - Make synack_ecn_bytes as static const array and use const u32 pointer in tcp_options_write() of #11 (Paolo Abeni <pabeni(a)redhat.com>) - Use ALIGN() and ALIGN_DOWN() in tcp_options_fit_accecn() to pad TCP AccECN option to dword of #11 (Paolo Abeni <pabeni(a)redhat.com>) - Return TCP_ACCECN_OPT_FAIL_SEEN if WARN_ON_ONCE() is true in tcp_accecn_option_init() of #12 (Paolo Abeni <pabeni(a)redhat.com>) v12 (04-Jul-2025) - Fix compilation issues with some intermediate patches in v11 - Add more comments for AccECN helpers of tcp_ecn.h v11 (03-Jul-2025) - Fix compilation issues with some intermediate patches in v10 v10 (02-Jul-2025) - Add new patch of separated header file include/net/tcp_ecn.h to include ECN and AccECN functions (Eric Dumazet <edumazet(a)google.com>) - Add comments on the AccECN helper functions in tcp_ecn.h (Eric Dumazet <edumazet(a)google.com>) - Add documentation of tcp_ecn, tcp_ecn_option, tcp_ecn_beacon in ip-sysctl.rst to the corresponding patch (Eric Dumazet <edumazet(a)google.com>) - Split wait third ACK functionality into a separated patch from AccECN negotiation patch (Eric Dumazet <edumazet(a)google.com>) - Add READ_ONCE() over every reads of sysctl for all patches in the series (Eric Dumazet <edumazet(a)google.com>) - Merge heuristics of AccECN option ceb/cep and ACE field multi-wrap into a single patch - Add a table of SACK block reduction and required AccECN field in patch #15 commit message (Eric Dumazet <edumazet(a)google.com>) v9 (21-Jun-2025) - Use tcp_data_ecn_check() to set TCP_ECN_SEE flag only for RFC3168 ECN (Paolo Abeni <pabeni(a)redhat.com>) - Add comments about setting TCP_ECN_SEEN flag for RFC3168 and Accruate ECN (Paolo Abeni <pabeni(a)redhat.com>) - Restruct the code in the for loop of tcp_accecn_process_option() (Paolo Abeni <pabeni(a)redhat.com>) - Remove ecn_bytes and add use_synack_ecn_bytes flag to identify whether syn_ack_bytes or received_ecn_bytes is used (Paolo Abeni <pabeni(a)redhat.com>) - Replace leftover_bytes and leftover_size with leftover_highbyte and leftover_lowbyte and add comments in tcp_options_write() (Paolo Abeni <pabeni(a)redhat.com>) - Add comments and commit message about the 1st retx SYN still attempt AccECN negotiation (Paolo Abeni <pabeni(a)redhat.com>) v8 (10-Jun-2025) - Add new helper function tcp_ecn_received_counters_payload() in #6 (Paolo Abeni <pabeni(a)redhat.com>) - Set opts->num_sack_blocks=0 to avoid potential undefined value in #8 (Paolo Abeni <pabeni(a)redhat.com>) - Reset leftover_size to 2 once leftover_bytes is used in #9 (Paolo Abeni <pabeni(a)redhat.com>) - Add new helper function tcp_accecn_opt_demand_min() in #10 (Paolo Abeni <pabeni(a)redhat.com>) - Add new helper function tcp_accecn_saw_opt_fail_recv() in #11 (Paolo Abeni <pabeni(a)redhat.com>) - Update tcp_options_fit_accecn() to avoid using recursion in #14 (Paolo Abeni <pabeni(a)redhat.com>) v7 (14-May-2025) - Modify group sizes of tcp_sock_write_txrx and tcp_sock_write_rx in #3 based on pahole results (Paolo Abeni <pabeni(a)redhat.com>) - Fix the issue in #4 and #5 where the RFC3168 ECN behavior in tcp_ecn_send() is changed (Paolo Abeni <pabeni(a)redhat.com>) - Modify group size of tcp_sock_write_txrx in #4 and #6 based on pahole results (Paolo Abeni <pabeni(a)redhat.com>) - Update commit message for #9 to explain the increase in tcp_sock_write_rx group size - Modify group size of tcp_sock_write_tx in #10 based on pahole results v6 (09-May-2025) - Add #3 to utilize exisintg holes of tcp_sock_write_txrx group for later patches (#4, #9, #10) with new u8 members (Paolo Abeni <pabeni(a)redhat.com>) - Add pahole outcomes before and after commit in #4, #5, #6, #9, #10, #15 (Paolo Abeni <pabeni(a)redhat.com>) - Define new helper function tcp_send_ack_reflect_ect() for sending ACK with reflected ECT in #5 (Paolo Abeni <pabeni(a)redhat.com>) - Add comments for function tcp_ecn_rcv_synack() in #5 (Paolo Abeni <pabeni(a)redhat.com>) - Add enum/define to be used by sysctl_tcp_ecn in #5, sysctl_tcp_ecn_option in #9, and sysctl_tcp_ecn_option_beacon in #10 (Paolo Abeni <pabeni(a)redhat.com>) - Move accecn_fail_mode and saw_accecn_opt in #5 and #11 to use exisintg holes of tcp_sock (Paolo Abeni <pabeni(a)redhat.com>) - Change data type of new members of tcp_request_sock and move them to the end of struct in #5 and #11 (Paolo Abeni <pabeni(a)redhat.com>) - Move new members of tcp_info to the end of struct in #6 (Paolo Abeni <pabeni(a)redhat.com>) - Merge previous #7 into #9 (Paolo Abeni <pabeni(a)redhat.com>) - Mask ecnfield with INET_ECN_MASK to remove WARN_ONCE in #9 (Paolo Abeni <pabeni(a)redhat.com>) - Reduce the indentation levels for reabability in #9 and #10 (Paolo Abeni <pabeni(a)redhat.com>) - Move delivered_ecn_bytes to the RX group in #9, accecn_opt_tstamp to the TX group in #10, pkts_acked_ewma to the RX group in #15 (Paolo Abeni <pabeni(a)redhat.com>) - Add changes in Documentation/networking/net_cachelines/tcp_sock.rst for new tcp_sock members in #3, #5, #6, #9, #10, #15 v5 (22-Apr-2025) - Further fix for 32-bit ARM alignment in tcp.c (Simon Horman <horms(a)kernel.org>) v4 (18-Apr-2025) - Fix 32-bit ARM assertion for alignment requirement (Simon Horman <horms(a)kernel.org>) v3 (14-Apr-2025) - Fix patch apply issue in v2 (Jakub Kicinski <kuba(a)kernel.org>) v2 (18-Mar-2025) - Add one missing patch from the previous AccECN protocol preparation patch series to this patch series. --- Chia-Yu Chang (5): tcp: reorganize tcp_sock_write_txrx group for variables later tcp: ecn functions in separated include file tcp: accecn: AccECN option send control tcp: accecn: AccECN option failure handling tcp: accecn: try to fit AccECN option with SACK Ilpo Järvinen (9): tcp: reorganize SYN ECN code tcp: fast path functions later tcp: AccECN core tcp: accecn: AccECN negotiation tcp: accecn: add AccECN rx byte counters tcp: accecn: AccECN needs to know delivered bytes tcp: sack option handling improvements tcp: accecn: AccECN option tcp: accecn: AccECN option ceb/cep and ACE field multi-wrap heuristics Documentation/networking/ip-sysctl.rst | 55 +- .../networking/net_cachelines/tcp_sock.rst | 12 + include/linux/tcp.h | 32 +- include/net/netns/ipv4.h | 2 + include/net/tcp.h | 87 ++- include/net/tcp_ecn.h | 642 ++++++++++++++++++ include/uapi/linux/tcp.h | 9 + net/ipv4/syncookies.c | 4 + net/ipv4/sysctl_net_ipv4.c | 19 + net/ipv4/tcp.c | 30 +- net/ipv4/tcp_input.c | 353 ++++++++-- net/ipv4/tcp_ipv4.c | 8 +- net/ipv4/tcp_minisocks.c | 40 +- net/ipv4/tcp_output.c | 294 ++++++-- net/ipv6/syncookies.c | 2 + net/ipv6/tcp_ipv6.c | 1 + 16 files changed, 1406 insertions(+), 184 deletions(-) create mode 100644 include/net/tcp_ecn.h -- 2.34.1

3 months

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next-20250909: selftests/arm64/gcs/basic-gcs.c:390:30: error: use of undeclared identifier 'HWCAP_GCS'

by Naresh Kamboju

The following build warnings / errors noticed on arm64 defconfig with clang-20 and gcc-13 toolchains on the Linux next-20250909 till next-20250911 tag while building selftests/arm64. Regression Analysis: - New regression? Yes - Reproducibility? yes First seen on next-20250909 Good: next-20250908 Bad: next-20250909 till next-20250911 Test regression: next-20250909: selftests/arm64/gcs/basic-gcs.c:390:30: error: use of undeclared identifier 'HWCAP_GCS' Reported-by: Linux Kernel Functional Testing <lkft(a)linaro.org> ## Build log selftests/arm64/gcs/basic-gcs.c:390:30: error: use of undeclared identifier 'HWCAP_GCS' 390 | if (!(getauxval(AT_HWCAP) & HWCAP_GCS)) | ^ 1 error generated. The suspected commit pointing to, kselftest/arm64/gcs: Use nolibc's getauxval() a985fe638344492727528e52416211dda1c391d5 ## Source * Kernel version: 6.17.0-rc5 * Git tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git * Git describe: 6.17.0-rc5-next-20250911 * Git commit: 8f21d9da46702c4d6951ba60ca8a05f42870fe8f * Architectures: arm64 * Toolchains: gcc-13 and clang-20 * Kconfigs: defconfig ## Build * Build log: https://qa-reports.linaro.org/api/testruns/29827060/log_file/ * Build details: https://regressions.linaro.org/lkft/linux-next-master/next-20250909/log-par… * Build plan: https://tuxapi.tuxsuite.com/v1/groups/linaro/projects/lkft/builds/32RzudgbC… * Build link: https://storage.tuxsuite.com/public/linaro/lkft/builds/32RzudgbCUiqGUoFtquJ… * Kernel config: https://storage.tuxsuite.com/public/linaro/lkft/builds/32RzudgbCUiqGUoFtquJ… ## Steps to reproduce $ tuxmake --runtime podman --target-arch arm64 \ --toolchain clang-nightly \ --kconfig https://storage.tuxsuite.com/public/linaro/lkft/builds/32RzudgbCUiqGUoFtquJ… \ LLVM=1 LLVM_IAS=1 debugkernel dtbs dtbs-legacy headers kernel kselftest modules -- Linaro LKFT

3 months

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[PATCH v3 bpf-next] selftests/bpf: Fix arena_spin_lock selftest failure

by Saket Kumar Bhaskar

For systems having CONFIG_NR_CPUS set to > 1024 in kernel config the selftest fails as arena_spin_lock_irqsave() returns EOPNOTSUPP. (eg - incase of powerpc default value for CONFIG_NR_CPUS is 8192) The selftest is skipped incase bpf program returns EOPNOTSUPP, with a descriptive message logged. Tested-by: Venkat Rao Bagalkote <venkat88(a)linux.ibm.com> Signed-off-by: Saket Kumar Bhaskar <skb99(a)linux.ibm.com> --- Changes since v2: * Separated arena_spin_lock selftest fix patch from the arena patchset as it has to go via bpf-next tree. * For EOPNOTSUPP set test_skip to 3, to differentiate it from scenarios when run conditions are not met as suggested by Hari. * Tweaked message displayed on SKIP to remove display of online cpus. v2:https://lore.kernel.org/all/20250829165135.1273071-1-skb99@linux.ibm.com/ Changes since v1: Addressed comments from Alexei: * Removed skel->rodata->nr_cpus = get_nprocs() and its usage to get currently online cpus(as it needs to be updated from userspace). v1:https://lore.kernel.org/all/20250805062747.3479221-1-skb99@linux.ibm.com/ --- .../selftests/bpf/prog_tests/arena_spin_lock.c | 13 +++++++++++++ tools/testing/selftests/bpf/progs/arena_spin_lock.c | 5 ++++- 2 files changed, 17 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c b/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c index 0223fce4db2b..693fd86fbde6 100644 --- a/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c +++ b/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c @@ -40,8 +40,13 @@ static void *spin_lock_thread(void *arg) err = bpf_prog_test_run_opts(prog_fd, &topts); ASSERT_OK(err, "test_run err"); + + if (topts.retval == -EOPNOTSUPP) + goto end; + ASSERT_EQ((int)topts.retval, 0, "test_run retval"); +end: pthread_exit(arg); } @@ -63,6 +68,7 @@ static void test_arena_spin_lock_size(int size) skel = arena_spin_lock__open_and_load(); if (!ASSERT_OK_PTR(skel, "arena_spin_lock__open_and_load")) return; + if (skel->data->test_skip == 2) { test__skip(); goto end; @@ -86,6 +92,13 @@ static void test_arena_spin_lock_size(int size) goto end_barrier; } + if (skel->data->test_skip == 3) { + printf("%s:SKIP: CONFIG_NR_CPUS exceed the maximum supported by arena spinlock\n", + __func__); + test__skip(); + goto end_barrier; + } + ASSERT_EQ(skel->bss->counter, repeat * nthreads, "check counter value"); end_barrier: diff --git a/tools/testing/selftests/bpf/progs/arena_spin_lock.c b/tools/testing/selftests/bpf/progs/arena_spin_lock.c index c4500c37f85e..086b57a426cf 100644 --- a/tools/testing/selftests/bpf/progs/arena_spin_lock.c +++ b/tools/testing/selftests/bpf/progs/arena_spin_lock.c @@ -37,8 +37,11 @@ int prog(void *ctx) #if defined(ENABLE_ATOMICS_TESTS) && defined(__BPF_FEATURE_ADDR_SPACE_CAST) unsigned long flags; - if ((ret = arena_spin_lock_irqsave(&lock, flags))) + if ((ret = arena_spin_lock_irqsave(&lock, flags))) { + if (ret == -EOPNOTSUPP) + test_skip = 3; return ret; + } if (counter != limit) counter++; bpf_repeat(cs_count); -- 2.43.5

3 months

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[PATCH RESEND v2] kunit: Enable PCI on UML without triggering WARN()

by Thomas Weißschuh

Various KUnit tests require PCI infrastructure to work. All normal platforms enable PCI by default, but UML does not. Enabling PCI from .kunitconfig files is problematic as it would not be portable. So in commit 6fc3a8636a7b ("kunit: tool: Enable virtio/PCI by default on UML") PCI was enabled by way of CONFIG_UML_PCI_OVER_VIRTIO=y. However CONFIG_UML_PCI_OVER_VIRTIO requires additional configuration of CONFIG_UML_PCI_OVER_VIRTIO_DEVICE_ID or will otherwise trigger a WARN() in virtio_pcidev_init(). However there is no one correct value for UML_PCI_OVER_VIRTIO_DEVICE_ID which could be used by default. This warning is confusing when debugging test failures. On the other hand, the functionality of CONFIG_UML_PCI_OVER_VIRTIO is not used at all, given that it is completely non-functional as indicated by the WARN() in question. Instead it is only used as a way to enable CONFIG_UML_PCI which itself is not directly configurable. Instead of going through CONFIG_UML_PCI_OVER_VIRTIO, introduce a custom configuration option which enables CONFIG_UML_PCI without triggering warnings or building dead code. Signed-off-by: Thomas Weißschuh <thomas.weissschuh(a)linutronix.de> Reviewed-by: Johannes Berg <johannes(a)sipsolutions.net> --- Changes in v2: - Rebase onto v6.17-rc1 - Pick up review from Johannes - Link to v1: https://lore.kernel.org/r/20250627-kunit-uml-pci-v1-1-a622fa445e58@linutron… --- lib/kunit/Kconfig | 7 +++++++ tools/testing/kunit/configs/arch_uml.config | 5 ++--- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/lib/kunit/Kconfig b/lib/kunit/Kconfig index c10ede4b1d2201d5f8cddeb71cc5096e21be9b6a..1823539e96da30e165fa8d395ccbd3f6754c836e 100644 --- a/lib/kunit/Kconfig +++ b/lib/kunit/Kconfig @@ -106,4 +106,11 @@ config KUNIT_DEFAULT_TIMEOUT If unsure, the default timeout of 300 seconds is suitable for most cases. +config KUNIT_UML_PCI + bool "KUnit UML PCI Support" + depends on UML + select UML_PCI + help + Enables the PCI subsystem on UML for use by KUnit tests. + endif # KUNIT diff --git a/tools/testing/kunit/configs/arch_uml.config b/tools/testing/kunit/configs/arch_uml.config index 54ad8972681a2cc724e6122b19407188910b9025..28edf816aa70e6f408d9486efff8898df79ee090 100644 --- a/tools/testing/kunit/configs/arch_uml.config +++ b/tools/testing/kunit/configs/arch_uml.config @@ -1,8 +1,7 @@ # Config options which are added to UML builds by default -# Enable virtio/pci, as a lot of tests require it. -CONFIG_VIRTIO_UML=y -CONFIG_UML_PCI_OVER_VIRTIO=y +# Enable pci, as a lot of tests require it. +CONFIG_KUNIT_UML_PCI=y # Enable FORTIFY_SOURCE for wider checking. CONFIG_FORTIFY_SOURCE=y --- base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585 change-id: 20250626-kunit-uml-pci-a2b687553746 Best regards, -- Thomas Weißschuh <thomas.weissschuh(a)linutronix.de>

3 months

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[PATCH 0/2] selftests/mm: Add -Wunreachable-code and fix warnings

by Muhammad Usama Anjum

This series is trimmed down version of previous more generic series[1]. In this new series, only -wunreachable-code flag is being added and dead code is being removed from generated warnings. [1] https://lore.kernel.org/all/20250822082145.4145617-1-usama.anjum@collabora.… Muhammad Usama Anjum (2): selftests/mm: Add -Wunreachable-code and fix warnings selftests/mm: protection_keys: Fix dead code tools/testing/selftests/mm/Makefile | 1 + tools/testing/selftests/mm/hmm-tests.c | 5 ++--- tools/testing/selftests/mm/pkey_sighandler_tests.c | 2 +- tools/testing/selftests/mm/protection_keys.c | 4 +--- tools/testing/selftests/mm/split_huge_page_test.c | 2 +- 5 files changed, 6 insertions(+), 8 deletions(-) -- 2.47.3

3 months

3
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[PATCH v20 0/8] fork: Support shadow stacks in clone3()

by Mark Brown

[ I think at this point everyone is OK with the ABI, and the x86 implementation has been tested so hopefully we are near to being able to get this merged? If there are any outstanding issues let me know and I can look at addressing them. The one possible issue I am aware of is that the RISC-V shadow stack support was briefly in -next but got dropped along with the general RISC-V issues during the last merge window, rebasing for that is still in progress. I guess ideally this could be applied on a branch and then pulled into the RISC-V tree? ] The kernel has recently added support for shadow stacks, currently x86 only using their CET feature but both arm64 and RISC-V have equivalent features (GCS and Zicfiss respectively), I am actively working on GCS[1]. With shadow stacks the hardware maintains an additional stack containing only the return addresses for branch instructions which is not generally writeable by userspace and ensures that any returns are to the recorded addresses. This provides some protection against ROP attacks and making it easier to collect call stacks. These shadow stacks are allocated in the address space of the userspace process. Our API for shadow stacks does not currently offer userspace any flexiblity for managing the allocation of shadow stacks for newly created threads, instead the kernel allocates a new shadow stack with the same size as the normal stack whenever a thread is created with the feature enabled. The stacks allocated in this way are freed by the kernel when the thread exits or shadow stacks are disabled for the thread. This lack of flexibility and control isn't ideal, in the vast majority of cases the shadow stack will be over allocated and the implicit allocation and deallocation is not consistent with other interfaces. As far as I can tell the interface is done in this manner mainly because the shadow stack patches were in development since before clone3() was implemented. Since clone3() is readily extensible let's add support for specifying a shadow stack when creating a new thread or process, keeping the current implicit allocation behaviour if one is not specified either with clone3() or through the use of clone(). The user must provide a shadow stack pointer, this must point to memory mapped for use as a shadow stackby map_shadow_stack() with an architecture specified shadow stack token at the top of the stack. Yuri Khrustalev has raised questions from the libc side regarding discoverability of extended clone3() structure sizes[2], this seems like a general issue with clone3(). There was a suggestion to add a hwcap on arm64 which isn't ideal but is doable there, though architecture specific mechanisms would also be needed for x86 (and RISC-V if it's support gets merged before this does). The idea has, however, had strong pushback from the architecture maintainers and it is possible to detect support for this in clone3() by attempting a call with a misaligned shadow stack pointer specified so no hwcap has been added. [1] https://lore.kernel.org/linux-arm-kernel/20241001-arm64-gcs-v13-0-222b78d87… [2] https://lore.kernel.org/r/aCs65ccRQtJBnZ_5@arm.com Signed-off-by: Mark Brown <broonie(a)kernel.org> --- Changes in v20: - Comment fixes and clarifications in x86 arch_shstk_validate_clone() from Rick Edgecombe. - Spelling fix in documentation. - Link to v19: https://lore.kernel.org/r/20250819-clone3-shadow-stack-v19-0-bc957075479b@k… Changes in v19: - Rebase onto v6.17-rc1. - Link to v18: https://lore.kernel.org/r/20250702-clone3-shadow-stack-v18-0-7965d2b694db@k… Changes in v18: - Rebase onto v6.16-rc3. - Thanks to pointers from Yuri Khrustalev this version has been tested on x86 so I have removed the RFT tag. - Clarify clone3_shadow_stack_valid() comment about the Kconfig check. - Remove redundant GCSB DSYNCs in arm64 code. - Fix token validation on x86. - Link to v17: https://lore.kernel.org/r/20250609-clone3-shadow-stack-v17-0-8840ed97ff6f@k… Changes in v17: - Rebase onto v6.16-rc1. - Link to v16: https://lore.kernel.org/r/20250416-clone3-shadow-stack-v16-0-2ffc9ca3917b@k… Changes in v16: - Rebase onto v6.15-rc2. - Roll in fixes from x86 testing from Rick Edgecombe. - Rework so that the argument is shadow_stack_token. - Link to v15: https://lore.kernel.org/r/20250408-clone3-shadow-stack-v15-0-3fa245c6e3be@k… Changes in v15: - Rebase onto v6.15-rc1. - Link to v14: https://lore.kernel.org/r/20250206-clone3-shadow-stack-v14-0-805b53af73b9@k… Changes in v14: - Rebase onto v6.14-rc1. - Link to v13: https://lore.kernel.org/r/20241203-clone3-shadow-stack-v13-0-93b89a81a5ed@k… Changes in v13: - Rebase onto v6.13-rc1. - Link to v12: https://lore.kernel.org/r/20241031-clone3-shadow-stack-v12-0-7183eb8bee17@k… Changes in v12: - Add the regular prctl() to the userspace API document since arm64 support is queued in -next. - Link to v11: https://lore.kernel.org/r/20241005-clone3-shadow-stack-v11-0-2a6a2bd6d651@k… Changes in v11: - Rebase onto arm64 for-next/gcs, which is based on v6.12-rc1, and integrate arm64 support. - Rework the interface to specify a shadow stack pointer rather than a base and size like we do for the regular stack. - Link to v10: https://lore.kernel.org/r/20240821-clone3-shadow-stack-v10-0-06e8797b9445@k… Changes in v10: - Integrate fixes & improvements for the x86 implementation from Rick Edgecombe. - Require that the shadow stack be VM_WRITE. - Require that the shadow stack base and size be sizeof(void *) aligned. - Clean up trailing newline. - Link to v9: https://lore.kernel.org/r/20240819-clone3-shadow-stack-v9-0-962d74f99464@ke… Changes in v9: - Pull token validation earlier and report problems with an error return to parent rather than signal delivery to the child. - Verify that the top of the supplied shadow stack is VM_SHADOW_STACK. - Rework token validation to only do the page mapping once. - Drop no longer needed support for testing for signals in selftest. - Fix typo in comments. - Link to v8: https://lore.kernel.org/r/20240808-clone3-shadow-stack-v8-0-0acf37caf14c@ke… Changes in v8: - Fix token verification with user specified shadow stack. - Don't track user managed shadow stacks for child processes. - Link to v7: https://lore.kernel.org/r/20240731-clone3-shadow-stack-v7-0-a9532eebfb1d@ke… Changes in v7: - Rebase onto v6.11-rc1. - Typo fixes. - Link to v6: https://lore.kernel.org/r/20240623-clone3-shadow-stack-v6-0-9ee7783b1fb9@ke… Changes in v6: - Rebase onto v6.10-rc3. - Ensure we don't try to free the parent shadow stack in error paths of x86 arch code. - Spelling fixes in userspace API document. - Additional cleanups and improvements to the clone3() tests to support the shadow stack tests. - Link to v5: https://lore.kernel.org/r/20240203-clone3-shadow-stack-v5-0-322c69598e4b@ke… Changes in v5: - Rebase onto v6.8-rc2. - Rework ABI to have the user allocate the shadow stack memory with map_shadow_stack() and a token. - Force inlining of the x86 shadow stack enablement. - Move shadow stack enablement out into a shared header for reuse by other tests. - Link to v4: https://lore.kernel.org/r/20231128-clone3-shadow-stack-v4-0-8b28ffe4f676@ke… Changes in v4: - Formatting changes. - Use a define for minimum shadow stack size and move some basic validation to fork.c. - Link to v3: https://lore.kernel.org/r/20231120-clone3-shadow-stack-v3-0-a7b8ed3e2acc@ke… Changes in v3: - Rebase onto v6.7-rc2. - Remove stale shadow_stack in internal kargs. - If a shadow stack is specified unconditionally use it regardless of CLONE_ parameters. - Force enable shadow stacks in the selftest. - Update changelogs for RISC-V feature rename. - Link to v2: https://lore.kernel.org/r/20231114-clone3-shadow-stack-v2-0-b613f8681155@ke… Changes in v2: - Rebase onto v6.7-rc1. - Remove ability to provide preallocated shadow stack, just specify the desired size. - Link to v1: https://lore.kernel.org/r/20231023-clone3-shadow-stack-v1-0-d867d0b5d4d0@ke… --- Mark Brown (8): arm64/gcs: Return a success value from gcs_alloc_thread_stack() Documentation: userspace-api: Add shadow stack API documentation selftests: Provide helper header for shadow stack testing fork: Add shadow stack support to clone3() selftests/clone3: Remove redundant flushes of output streams selftests/clone3: Factor more of main loop into test_clone3() selftests/clone3: Allow tests to flag if -E2BIG is a valid error code selftests/clone3: Test shadow stack support Documentation/userspace-api/index.rst | 1 + Documentation/userspace-api/shadow_stack.rst | 44 +++++ arch/arm64/include/asm/gcs.h | 8 +- arch/arm64/kernel/process.c | 8 +- arch/arm64/mm/gcs.c | 55 +++++- arch/x86/include/asm/shstk.h | 11 +- arch/x86/kernel/process.c | 2 +- arch/x86/kernel/shstk.c | 53 ++++- include/asm-generic/cacheflush.h | 11 ++ include/linux/sched/task.h | 17 ++ include/uapi/linux/sched.h | 9 +- kernel/fork.c | 93 +++++++-- tools/testing/selftests/clone3/clone3.c | 226 ++++++++++++++++++---- tools/testing/selftests/clone3/clone3_selftests.h | 65 ++++++- tools/testing/selftests/ksft_shstk.h | 98 ++++++++++ 15 files changed, 620 insertions(+), 81 deletions(-) --- base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585 change-id: 20231019-clone3-shadow-stack-15d40d2bf536 Best regards, -- Mark Brown <broonie(a)kernel.org>

3 months

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[PATCH v4 0/4] procfs: make reference pidns more user-visible

by Aleksa Sarai

Ever since the introduction of pid namespaces, procfs has had very implicit behaviour surrounding them (the pidns used by a procfs mount is auto-selected based on the mounting process's active pidns, and the pidns itself is basically hidden once the mount has been constructed). /* pidns mount option for procfs */ This implicit behaviour has historically meant that userspace was required to do some special dances in order to configure the pidns of a procfs mount as desired. Examples include: * In order to bypass the mnt_too_revealing() check, Kubernetes creates a procfs mount from an empty pidns so that user namespaced containers can be nested (without this, the nested containers would fail to mount procfs). But this requires forking off a helper process because you cannot just one-shot this using mount(2). * Container runtimes in general need to fork into a container before configuring its mounts, which can lead to security issues in the case of shared-pidns containers (a privileged process in the pidns can interact with your container runtime process). While SUID_DUMP_DISABLE and user namespaces make this less of an issue, the strict need for this due to a minor uAPI wart is kind of unfortunate. Things would be much easier if there was a way for userspace to just specify the pidns they want. Patch 1 implements a new "pidns" argument which can be set using fsconfig(2): fsconfig(procfd, FSCONFIG_SET_FD, "pidns", NULL, nsfd); fsconfig(procfd, FSCONFIG_SET_STRING, "pidns", "/proc/self/ns/pid", 0); or classic mount(2) / mount(8): // mount -t proc -o pidns=/proc/self/ns/pid proc /tmp/proc mount("proc", "/tmp/proc", "proc", MS_..., "pidns=/proc/self/ns/pid"); The initial security model I have in this RFC is to be as conservative as possible and just mirror the security model for setns(2) -- which means that you can only set pidns=... to pid namespaces that your current pid namespace is a direct ancestor of and you have CAP_SYS_ADMIN privileges over the pid namespace. This fulfils the requirements of container runtimes, but I suspect that this may be too strict for some usecases. The pidns argument is not displayed in mountinfo -- it's not clear to me what value it would make sense to show (maybe we could just use ns_dname to provide an identifier for the namespace, but this number would be fairly useless to userspace). I'm open to suggestions. Note that PROCFS_GET_PID_NAMESPACE (see below) does at least let userspace get information about this outside of mountinfo. Note that you cannot change the pidns of an already-created procfs instance. The primary reason is that allowing this to be changed would require RCU-protecting proc_pid_ns(sb) and thus auditing all of fs/proc/* and some of the users in fs/* to make sure they wouldn't UAF the pid namespace. Since creating procfs instances is very cheap, it seems unnecessary to overcomplicate this upfront. Trying to reconfigure procfs this way errors out with -EBUSY. /* ioctl(PROCFS_GET_PID_NAMESPACE) */ In addition, being able to figure out what pid namespace is being used by a procfs mount is quite useful when you have an administrative process (such as a container runtime) which wants to figure out the correct way of mapping PIDs between its own namespace and the namespace for procfs (using NS_GET_{PID,TGID}_{IN,FROM}_PIDNS). There are alternative ways to do this, but they all rely on ancillary information that third-party libraries and tools do not necessarily have access to. To make this easier, add a new ioctl (PROCFS_GET_PID_NAMESPACE) which can be used to get a reference to the pidns that a procfs is using. Rather than copying the (fairly strict) security model for setns(2), apply a slightly looser model to better match what userspace can already do: * Make the ioctl only valid on the root (meaning that a process without access to the procfs root -- such as only having an fd to a procfs file or some open_tree(2)-like subset -- cannot use this API). This means that the process already has some level of access to the /proc/$pid directories. * If the calling process is in an ancestor pidns, then they can already create pidfd for processes inside the pidns, which is morally equivalent to a pidns file descriptor according to setns(2). So it seems reasonable to just allow it in this case. (The justification for this model was suggested by Christian.) * If the process has access to /proc/1/ns/pid already (i.e. has ptrace-read access to the pidns pid1), then this ioctl is equivalent to just opening a handle to it that way. Ideally we would check for ptrace-read access against all processes in the pidns (which is very likely to be true for at least one process, as SUID_DUMP_DISABLE is cleared on exec(2) and is rarely set by most programs), but this would obviously not scale. I'm open to suggestions for whether we need to make this stricter (or possibly allow more cases). Signed-off-by: Aleksa Sarai <cyphar(a)cyphar.com> --- Changes in v4: - Remove unneeded EXPORT_SYMBOL_GPL. [Christian Brauner] - Return -EOPNOTSUPP for new APIs for CONFIG_PID_NS=n rather than pretending they don't exist entirely. [Christian Brauner] - PROCFS_IOCTL_MAGIC conflicts with XSDFEC_MAGIC, so we need to allocate subvalues more carefully (switch to _IO(PROCFS_IOCTL_MAGIC, 32)). - Add some more selftests for PROCFS_GET_PID_NAMESPACE. - Reword argument for PROCFS_GET_PID_NAMESPACE security model based on Christian's suggestion, and remove CAP_SYS_ADMIN edge-case (in most cases, such a process would also have ptrace-read credentials over the pidns pid1). - v3: <https://lore.kernel.org/r/20250724-procfs-pidns-api-v3-0-4c685c910923@cypha…> Changes in v3: - Disallow changing pidns for existing procfs instances, as we'd probably have to RCU-protect everything that touches the pinned pidns reference. - Improve tests with slightly nicer ASSERT_ERRNO* macros. - v2: <https://lore.kernel.org/r/20250723-procfs-pidns-api-v2-0-621e7edd8e40@cypha…> Changes in v2: - #ifdef CONFIG_PID_NS - Improve cover letter wording to make it clear we're talking about two separate features with different permission models. [Andy Lutomirski] - Fix build warnings in pidns_is_ancestor() patch. [kernel test robot] - v1: <https://lore.kernel.org/r/20250721-procfs-pidns-api-v1-0-5cd9007e512d@cypha…> --- Aleksa Sarai (4): pidns: move is-ancestor logic to helper procfs: add "pidns" mount option procfs: add PROCFS_GET_PID_NAMESPACE ioctl selftests/proc: add tests for new pidns APIs Documentation/filesystems/proc.rst | 12 ++ fs/proc/root.c | 166 +++++++++++++++- include/linux/pid_namespace.h | 9 + include/uapi/linux/fs.h | 4 + kernel/pid_namespace.c | 22 ++- tools/testing/selftests/proc/.gitignore | 1 + tools/testing/selftests/proc/Makefile | 1 + tools/testing/selftests/proc/proc-pidns.c | 315 ++++++++++++++++++++++++++++++ 8 files changed, 514 insertions(+), 16 deletions(-) --- base-commit: 66639db858112bf6b0f76677f7517643d586e575 change-id: 20250717-procfs-pidns-api-8ed1583431f0 Best regards, -- Aleksa Sarai <cyphar(a)cyphar.com>

3 months

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[PATCH 0/9] Start porting UML to nolibc

by Benjamin Berg

From: Benjamin Berg <benjamin.berg(a)intel.com> For a while now, we have discussed that it may be better to avoid using libc inside UML as it may be interfering in unexpected ways with kernel functionality. A major point of concern is that there is no guarantee that the libc is not using any address space that may conflict with kernel addresses. This patchset is an attempt to start a nolibc port of UML. The goal is to port UML to use nolibc in smaller chunks to make the switch more manageable. There are three parts to this patchset: * Two patches to use tools/include headers instead of kernel headers for userspace files. * A few nolibc fixes and a new NOLIBC_NO_STARTCODE compile flag for it * Finally nolibc build support for UML and switching two files The first two parts could be merged independently. The last step to use nolibc inside UML obviously depends on the first two. Benjamin Benjamin Berg (9): tools compiler.h: fix __used definition um: use tools/include for user files tools/nolibc/stdio: remove perror if NOLIBC_IGNORE_ERRNO is set tools/nolibc/dirent: avoid errno in readdir_r tools/nolibc: use __fallthrough__ rather than fallthrough tools/nolibc: add option to disable startup code um: add infrastructure to build files using nolibc um: use nolibc for the --showconfig implementation um: switch ptrace FP register access to nolibc arch/um/Makefile | 32 ++++++++++++++++--- .../um/include/shared/generated/asm-offsets.h | 1 + .../include/shared/generated/user_constants.h | 1 + arch/um/include/shared/init.h | 2 +- arch/um/include/shared/os.h | 2 ++ arch/um/include/shared/user.h | 5 --- arch/um/kernel/Makefile | 2 +- arch/um/kernel/skas/stub.c | 1 + arch/um/kernel/skas/stub_exe.c | 4 +-- arch/um/os-Linux/skas/process.c | 6 ++-- arch/um/os-Linux/start_up.c | 4 +-- arch/um/scripts/Makefile.rules | 10 ++++-- arch/x86/um/Makefile | 6 ++-- arch/x86/um/os-Linux/Makefile | 5 ++- arch/x86/um/os-Linux/registers.c | 22 +++++-------- arch/x86/um/user-offsets.c | 1 - tools/include/linux/compiler.h | 2 +- tools/include/nolibc/arch-arm.h | 2 ++ tools/include/nolibc/arch-arm64.h | 2 ++ tools/include/nolibc/arch-loongarch.h | 2 ++ tools/include/nolibc/arch-m68k.h | 2 ++ tools/include/nolibc/arch-mips.h | 2 ++ tools/include/nolibc/arch-powerpc.h | 2 ++ tools/include/nolibc/arch-riscv.h | 2 ++ tools/include/nolibc/arch-s390.h | 2 ++ tools/include/nolibc/arch-sh.h | 2 ++ tools/include/nolibc/arch-sparc.h | 2 ++ tools/include/nolibc/arch-x86.h | 4 +++ tools/include/nolibc/compiler.h | 4 +-- tools/include/nolibc/crt.h | 3 ++ tools/include/nolibc/dirent.h | 6 ++-- tools/include/nolibc/stackprotector.h | 2 ++ tools/include/nolibc/stdio.h | 2 ++ tools/include/nolibc/stdlib.h | 2 ++ tools/include/nolibc/sys.h | 3 +- tools/include/nolibc/sys/auxv.h | 3 ++ 36 files changed, 108 insertions(+), 47 deletions(-) create mode 120000 arch/um/include/shared/generated/asm-offsets.h create mode 120000 arch/um/include/shared/generated/user_constants.h -- 2.51.0

3 months

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