- Linux-kselftest-mirror - lists.linaro.org

[PATCH net-next] selftest: netcons: create a torture test

by Breno Leitao

Create a netconsole test that puts a lot of pressure on the netconsole list manipulation. Do it by creating dynamic targets and deleting targets while messages are being sent. Also put interface down while the messages are being sent, as creating parallel targets. The code launches three background jobs on distinct schedules: * Toggle netcons target every 30 iterations * create and delete random_target every 50 iterations * toggle iface every 70 iterations This creates multiple concurrency sources that interact with netconsole states. This is good practice to simulate stress, and exercise netpoll and netconsole locks. This test already found an issue as reported in [1] Link: https://lore.kernel.org/all/20250901-netpoll_memleak-v1-1-34a181977dfc@debi… [1] Signed-off-by: Breno Leitao <leitao(a)debian.org> --- tools/testing/selftests/drivers/net/Makefile | 1 + .../selftests/drivers/net/netcons_torture.sh | 133 +++++++++++++++++++++ 2 files changed, 134 insertions(+) diff --git a/tools/testing/selftests/drivers/net/Makefile b/tools/testing/selftests/drivers/net/Makefile index 984ece05f7f92..2b253b1ff4f38 100644 --- a/tools/testing/selftests/drivers/net/Makefile +++ b/tools/testing/selftests/drivers/net/Makefile @@ -17,6 +17,7 @@ TEST_PROGS := \ netcons_fragmented_msg.sh \ netcons_overflow.sh \ netcons_sysdata.sh \ + netcons_torture.sh \ netpoll_basic.py \ ping.py \ queues.py \ diff --git a/tools/testing/selftests/drivers/net/netcons_torture.sh b/tools/testing/selftests/drivers/net/netcons_torture.sh new file mode 100755 index 0000000000000..d41884c83cab3 --- /dev/null +++ b/tools/testing/selftests/drivers/net/netcons_torture.sh @@ -0,0 +1,133 @@ +#!/usr/bin/env bash +# SPDX-License-Identifier: GPL-2.0 + +# Repeatedly send kernel messages, toggles netconsole targets on and off, +# creates and deletes targets in parallel, and toggles the source interface to +# simulate stress conditions. +# +# This test aims verify the robustness of netconsole under dynamic +# configurations and concurrent operations. +# +# The major goal is to run this test with LOCKDEP, Kmemleak and KASAN to make +# sure no issues is reported. +# +# Author: Breno Leitao <leitao(a)debian.org> + +set -euo pipefail + +SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")") + +source "${SCRIPTDIR}"/lib/sh/lib_netcons.sh + +# Number of times the main loop run +ITERATIONS=${1:-1000} + +# Only test extended format +FORMAT="extended" +# And ipv6 only +IP_VERSION="ipv6" + +# Create, enable and delete some targets. +create_and_delete_random_target() { + COUNT=1 + RND_PREFIX=$(mktemp -u netcons_rnd_XXXX_) + + if [ -d "${NETCONS_CONFIGFS}/${RND_PREFIX}${COUNT}" ] || \ + [ -d "${NETCONS_CONFIGFS}/${RND_PREFIX}0" ]; then + echo "Function didn't finish yet, skipping it." >&2 + return + fi + + # enable COUNT targets + for i in $(seq 0 ${COUNT}) + do + RND_TARGET="${RND_PREFIX}"${i} + RND_TARGET_PATH="${NETCONS_CONFIGFS}"/"${RND_TARGET}" + + # Basic population so the target can come up + mkdir "${RND_TARGET_PATH}" + echo "${DSTIP}" > "${RND_TARGET_PATH}"/remote_ip + echo "${SRCIP}" > "${RND_TARGET_PATH}"/local_ip + echo "${DSTMAC}" > "${RND_TARGET_PATH}"/remote_mac + echo "${SRCIF}" > "${RND_TARGET_PATH}"/dev_name + + echo 1 > "${RND_TARGET_PATH}"/enabled + done + + echo "netconsole selftest: ${COUNT} additional target was created" > /dev/kmsg + # disable them all + for i in $(seq 0 ${COUNT}) + do + RND_TARGET="${RND_PREFIX}"${i} + RND_TARGET_PATH="${NETCONS_CONFIGFS}"/"${RND_TARGET}" + echo 0 > "${RND_TARGET_PATH}"/enabled + rmdir "${RND_TARGET_PATH}" + done +} + +# Disable and enable the target mid-air, while messages +# are being transmitted. +toggle_netcons_target() { + for i in $(seq 2) + do + if [ ! -d "${NETCONS_PATH}" ] + then + break + fi + echo 0 > "${NETCONS_PATH}"/enabled 2> /dev/null || true + # Try to enable a bit harder, given it might fail to enable + # Write to `enabled` might fail depending on the lock, which is + # highly contentious here + for _ in $(seq 5) + do + echo 1 > "${NETCONS_PATH}"/enabled 2> /dev/null || true + done + done +} + +toggle_iface(){ + ip link set "${SRCIF}" down + ip link set "${SRCIF}" up +} + +# Start here + +modprobe netdevsim 2> /dev/null || true +modprobe netconsole 2> /dev/null || true + +# Check for basic system dependency and exit if not found +check_for_dependencies +# Set current loglevel to KERN_INFO(6), and default to KERN_NOTICE(5) +echo "6 5" > /proc/sys/kernel/printk +# Remove the namespace, interfaces and netconsole target on exit +trap cleanup EXIT +# Create one namespace and two interfaces +set_network "${IP_VERSION}" +# Create a dynamic target for netconsole +create_dynamic_target "${FORMAT}" + +for i in $(seq "$ITERATIONS") +do + for _ in $(seq 10) + do + echo "${MSG}: ${TARGET} ${i}" > /dev/kmsg + wait + done + + if (( i % 30 == 0 )); then + toggle_netcons_target & + fi + + if (( i % 50 == 0 )); then + # create some targets, enable them, send msg and disable + # all in a parallel thread + create_and_delete_random_target & + fi + + if (( i % 70 == 0 )); then + toggle_iface & + fi +done +wait + +exit "${ksft_pass}" --- base-commit: 2fd4161d0d2547650d9559d57fc67b4e0a26a9e3 change-id: 20250902-netconsole_torture-8fc23f0aca99 Best regards, -- Breno Leitao <leitao(a)debian.org>

1 week, 5 days

2
2
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[PATCH 0/8] riscv: add initial support for hardware breakpoints

by Jesse Taube

This patchset adds initial support for hardware breakpoints and watchpoints to the RISC-V architecture. The framework is built on top of perf subsystem and SBI debug trigger extension. Currently following features are not supported and are in works: - icount for single stepping - Virtualization of debug triggers - kernel space debug triggers The SBI debug trigger extension can be found at: https://github.com/riscv-non-isa/riscv-sbi-doc/blob/master/src/ext-debug-tr… The Sdtrig ISA is part of RISC-V debug specification which can be found at: https://github.com/riscv/riscv-debug-spec based off the original RFC by Himanshu Chauhan here: https://lore.kernel.org/lkml/20240222125059.13331-1-hchauhan@ventanamicro.c… Second RFC by Jesse Taube here: https://lore.kernel.org/lkml/20250722173829.984082-1-jesse@rivosinc.com/ Himanshu Chauhan (2): riscv: Add SBI debug trigger extension and function ids riscv: Introduce support for hardware break/watchpoints Jesse Taube (6): riscv: Add insn.c, consolidate instruction decoding riscv: insn: Add get_insn_nofault riscv: hw_breakpoint: Use icount for single stepping riscv: ptrace: Add hw breakpoint support riscv: ptrace: Add hw breakpoint regset selftests: riscv: Add test for hardware breakpoints arch/riscv/Kconfig | 2 + arch/riscv/include/asm/bug.h | 12 - arch/riscv/include/asm/hw_breakpoint.h | 59 ++ arch/riscv/include/asm/insn.h | 132 ++- arch/riscv/include/asm/kdebug.h | 3 +- arch/riscv/include/asm/processor.h | 4 + arch/riscv/include/asm/sbi.h | 33 +- arch/riscv/include/uapi/asm/ptrace.h | 9 + arch/riscv/kernel/Makefile | 2 + arch/riscv/kernel/hw_breakpoint.c | 763 ++++++++++++++++++ arch/riscv/kernel/insn.c | 165 ++++ arch/riscv/kernel/kgdb.c | 102 +-- arch/riscv/kernel/probes/kprobes.c | 1 + arch/riscv/kernel/process.c | 4 + arch/riscv/kernel/ptrace.c | 169 ++++ arch/riscv/kernel/traps.c | 11 +- arch/riscv/kernel/traps_misaligned.c | 93 +-- include/uapi/linux/elf.h | 2 + tools/include/uapi/linux/elf.h | 1 + tools/perf/tests/tests.h | 3 +- tools/testing/selftests/riscv/Makefile | 2 +- .../selftests/riscv/breakpoints/.gitignore | 1 + .../selftests/riscv/breakpoints/Makefile | 13 + .../riscv/breakpoints/breakpoint_test.c | 246 ++++++ 24 files changed, 1641 insertions(+), 191 deletions(-) create mode 100644 arch/riscv/include/asm/hw_breakpoint.h create mode 100644 arch/riscv/kernel/hw_breakpoint.c create mode 100644 arch/riscv/kernel/insn.c create mode 100644 tools/testing/selftests/riscv/breakpoints/.gitignore create mode 100644 tools/testing/selftests/riscv/breakpoints/Makefile create mode 100644 tools/testing/selftests/riscv/breakpoints/breakpoint_test.c -- 2.43.0

1 week, 5 days

5
14
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[PATCH v9 00/19] TDX KVM selftests

by Sagi Shahar

This is v9 of the TDX selftests. Thanks everyone for the thorough review on v8 [1]. I tried addressing all the comments. I'm terribly sorry if I missed something. The original v8 series [1] was split to make reviewing the test framework changes easier. This series includes the original patches up to the TDX lifecycle test which is the first TDX selftest in the series. This series is based on v6.17-rc2 Changes from v8: - Rebased on top of v6.17-rc2 - Drop several patches which are no longer needed now that TDX support is integrated into the common flow. - Split several patches to make reviewing easier. - Massive refactor compared to v8 to pull TDX special handling into __vm_create() and vm_vcpu_add() instead of creating separate functions for TDX. - Use kbuild to expose values from c to assembly code. - Move setup of the reset vectors to c code as suggested by Sean. - Drop redundant cpuid masking functions which are no longer necessary. - Initialize TDX protected pages one at a time instead of allocating large chinks of memory. - Add UCALL support for TDX to align with the rest of the selftests. - Minor fixes to kselftest_harness.h and virt_map() that were identified as part of this work. [1] https://lore.kernel.org/lkml/20250807201628.1185915-1-sagis@google.com/ Ackerley Tng (2): KVM: selftests: Add helpers to init TDX memory and finalize VM KVM: selftests: Add ucall support for TDX Erdem Aktas (2): KVM: selftests: Add TDX boot code KVM: selftests: Add support for TDX TDCALL from guest Isaku Yamahata (2): KVM: selftests: Update kvm_init_vm_address_properties() for TDX KVM: selftests: TDX: Use KVM_TDX_CAPABILITIES to validate TDs' attribute configuration Sagi Shahar (13): KVM: selftests: Include overflow.h instead of redefining is_signed_type() KVM: selftests: Allocate pgd in virt_map() as necessary KVM: selftests: Expose functions to get default sregs values KVM: selftests: Expose function to allocate guest vCPU stack KVM: selftests: Expose segment definitons to assembly files KVM: selftests: Add kbuild definitons KVM: selftests: Define structs to pass parameters to TDX boot code KVM: selftests: Set up TDX boot code region KVM: selftests: Set up TDX boot parameters region KVM: selftests: Add helper to initialize TDX VM KVM: selftests: Hook TDX support to vm and vcpu creation KVM: selftests: Add wrapper for TDX MMIO from guest KVM: selftests: Add TDX lifecycle test tools/include/linux/kbuild.h | 18 + tools/testing/selftests/kselftest_harness.h | 3 +- tools/testing/selftests/kvm/Makefile.kvm | 32 ++ .../selftests/kvm/include/x86/processor.h | 8 + .../selftests/kvm/include/x86/processor_asm.h | 12 + .../selftests/kvm/include/x86/tdx/td_boot.h | 81 ++++ .../kvm/include/x86/tdx/td_boot_asm.h | 16 + .../selftests/kvm/include/x86/tdx/tdcall.h | 34 ++ .../selftests/kvm/include/x86/tdx/tdx.h | 14 + .../selftests/kvm/include/x86/tdx/tdx_util.h | 86 ++++ .../testing/selftests/kvm/include/x86/ucall.h | 4 +- tools/testing/selftests/kvm/lib/kvm_util.c | 25 +- .../testing/selftests/kvm/lib/x86/processor.c | 122 ++++-- .../selftests/kvm/lib/x86/tdx/td_boot.S | 60 +++ .../kvm/lib/x86/tdx/td_boot_offsets.c | 21 + .../selftests/kvm/lib/x86/tdx/tdcall.S | 93 +++++ .../kvm/lib/x86/tdx/tdcall_offsets.c | 16 + tools/testing/selftests/kvm/lib/x86/tdx/tdx.c | 22 + .../selftests/kvm/lib/x86/tdx/tdx_util.c | 391 ++++++++++++++++++ tools/testing/selftests/kvm/lib/x86/ucall.c | 45 +- tools/testing/selftests/kvm/x86/tdx_vm_test.c | 31 ++ 21 files changed, 1095 insertions(+), 39 deletions(-) create mode 100644 tools/include/linux/kbuild.h create mode 100644 tools/testing/selftests/kvm/include/x86/processor_asm.h create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/td_boot.h create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/td_boot_asm.h create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/tdcall.h create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/tdx.h create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/td_boot_offsets.c create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/tdcall.S create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/tdcall_offsets.c create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/tdx.c create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c create mode 100644 tools/testing/selftests/kvm/x86/tdx_vm_test.c -- 2.51.0.rc1.193.gad69d77794-goog

1 week, 5 days

6
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[PATCH net-next] selftests: net: Add tests to verify team driver option set and get.

by Marc Harvey

There are currently no kernel tests that verify setting and getting options of the team driver. In the future, options may be added that implicitly change other options, which will make it useful to have tests like these that show nothing breaks. There will be a follow up patch to this that adds new "rx_enabled" and "tx_enabled" options, which will implicitly affect the "enabled" option value and vice versa. The tests use teamnl to first set options to specific values and then gets them to compare to the set values. Signed-off-by: Marc Harvey <marcharvey(a)google.com> --- .../selftests/drivers/net/team/Makefile | 6 +- .../selftests/drivers/net/team/options.sh | 194 ++++++++++++++++++ 2 files changed, 198 insertions(+), 2 deletions(-) create mode 100755 tools/testing/selftests/drivers/net/team/options.sh diff --git a/tools/testing/selftests/drivers/net/team/Makefile b/tools/testing/selftests/drivers/net/team/Makefile index eaf6938f100e..8b00b70ce67f 100644 --- a/tools/testing/selftests/drivers/net/team/Makefile +++ b/tools/testing/selftests/drivers/net/team/Makefile @@ -1,11 +1,13 @@ # SPDX-License-Identifier: GPL-2.0 # Makefile for net selftests -TEST_PROGS := dev_addr_lists.sh propagation.sh +TEST_PROGS := dev_addr_lists.sh propagation.sh options.sh TEST_INCLUDES := \ ../bonding/lag_lib.sh \ ../../../net/forwarding/lib.sh \ - ../../../net/lib.sh + ../../../net/lib.sh \ + ../../../net/in_netns.sh \ + ../../../net/lib/sh/defer.sh \ include ../../../lib.mk diff --git a/tools/testing/selftests/drivers/net/team/options.sh b/tools/testing/selftests/drivers/net/team/options.sh new file mode 100755 index 000000000000..b9c7aa357ad5 --- /dev/null +++ b/tools/testing/selftests/drivers/net/team/options.sh @@ -0,0 +1,194 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 + +# These tests verify basic set and get functionality of the team +# driver options over netlink. + +# Run in private netns. +test_dir="$(dirname "$0")" +if [[ $# -eq 0 ]]; then + "${test_dir}"/../../../net/in_netns.sh "$0" __subprocess + exit $? +fi + +ALL_TESTS=" + team_test_options +" + +source "${test_dir}/../../../net/lib.sh" + +TEAM_PORT="team0" +MEMBER_PORT="dummy0" + +setup() +{ + ip link add name "${MEMBER_PORT}" type dummy + ip link add name "${TEAM_PORT}" type team +} + +get_and_check_value() +{ + local option_name="$1" + local expected_value="$2" + local port_flag="$3" + + local value_from_get + + value_from_get=$(teamnl "${TEAM_PORT}" getoption "${option_name}" \ + "${port_flag}") + if [[ $? != 0 ]]; then + echo "Could not get option '${option_name}'" >&2 + return 1 + fi + + if [[ "${value_from_get}" != "${expected_value}" ]]; then + echo "Incorrect value for option '${option_name}'" >&2 + echo "get (${value_from_get}) != set (${expected_value})" >&2 + return 1 + fi +} + +set_and_check_get() +{ + local option_name="$1" + local option_value="$2" + local port_flag="$3" + + local value_from_get + + teamnl "${TEAM_PORT}" setoption "${option_name}" "${option_value}" \ + "${port_flag}" + if [[ $? != 0 ]]; then + echo "'setoption ${option_name} ${option_value}' failed" >&2 + return 1 + fi + + get_and_check_value "${option_name}" "${option_value}" "${port_flag}" + return $? +} + +# Get a "port flag" to pass to the `teamnl` command. +# E.g. $?="dummy0" -> "port=dummy0", +# $?="" -> "" +get_port_flag() +{ + local port_name="$1" + + if [[ -n "${port_name}" ]]; then + echo "--port=${port_name}" + fi +} + +attach_port_if_specified() +{ + local port_name="${1}" + + if [[ -n "${port_name}" ]]; then + ip link set dev "${port_name}" master "${TEAM_PORT}" + return $? + fi +} + +detach_port_if_specified() +{ + local port_name="${1}" + + if [[ -n "${port_name}" ]]; then + ip link set dev "${port_name}" nomaster + return $? + fi +} + +####################################### +# Test that an option's get value matches its set value. +# Globals: +# RET - Used by testing infra like `check_err`. +# EXIT_STATUS - Used by `log_test` to whole script exit value. +# Arguments: +# option_name - The name of the option. +# value_1 - The first value to try setting. +# value_2 - The second value to try setting. +# port_name - The (optional) name of the attached port. +####################################### +team_test_option() +{ + local option_name="$1" + local value_1="$2" + local value_2="$3" + local possible_values="$2 $3 $2" + local port_name="$4" + local port_flag + + RET=0 + + echo "Setting '${option_name}' to '${value_1}' and '${value_2}'" + + attach_port_if_specified "${port_name}" + check_err $? "Couldn't attach ${port_name} to master" + port_flag=$(get_port_flag "${port_name}") + + # Set and get both possible values. + for value in ${possible_values}; do + set_and_check_get "${option_name}" "${value}" "${port_flag}" + check_err $? "Failed to set '${option_name}' to '${value}'" + done + + detach_port_if_specified "${port_name}" + check_err $? "Couldn't detach ${port_name} from its master" + + log_test "Set + Get '${option_name}' test" +} + +####################################### +# Test that getting a non-existant option fails. +# Globals: +# RET - Used by testing infra like `check_err`. +# EXIT_STATUS - Used by `log_test` to whole script exit value. +# Arguments: +# option_name - The name of the option. +# port_name - The (optional) name of the attached port. +####################################### +team_test_get_option_fails() +{ + local option_name="$1" + local port_name="$2" + local port_flag + + RET=0 + + attach_port_if_specified "${port_name}" + check_err $? "Couldn't attach ${port_name} to master" + port_flag=$(get_port_flag "${port_name}") + + # Just confirm that getting the value fails. + teamnl "${TEAM_PORT}" getoption "${option_name}" "${port_flag}" + check_fail $? "Shouldn't be able to get option '${option_name}'" + + detach_port_if_specified "${port_name}" + + log_test "Get '${option_name}' fails" +} + +team_test_options() +{ + # Wrong option name behavior. + team_test_get_option_fails fake_option1 + team_test_get_option_fails fake_option2 "${MEMBER_PORT}" + + # Correct set and get behavior. + team_test_option mode activebackup loadbalance + team_test_option notify_peers_count 0 5 + team_test_option notify_peers_interval 0 5 + team_test_option mcast_rejoin_count 0 5 + team_test_option mcast_rejoin_interval 0 5 + team_test_option enabled true false "${MEMBER_PORT}" + team_test_option user_linkup true false "${MEMBER_PORT}" + team_test_option user_linkup_enabled true false "${MEMBER_PORT}" + team_test_option priority 10 20 "${MEMBER_PORT}" + team_test_option queue_id 0 1 "${MEMBER_PORT}" +} + +require_command teamnl +setup +tests_run +exit "${EXIT_STATUS}" -- 2.51.0.355.g5224444f11-goog

1 week, 5 days

3
4
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[PATCH bpf-next v3 0/3] selftests/bpf: benchmark all symbols for kprobe-multi

by Menglong Dong

Add the benchmark testcase "kprobe-multi-all", which will hook all the kernel functions during the testing. This series is separated out from [1]. Changes since V2: * add some comment to attach_ksyms_all, which notes that don't run the testing on a debug kernel Changes since V1: * introduce trace_blacklist instead of copy-pasting strcmp in the 2nd patch * use fprintf() instead of printf() in 3rd patch Link: https://lore.kernel.org/bpf/20250817024607.296117-1-dongml2@chinatelecom.cn/ [1] Menglong Dong (3): selftests/bpf: move get_ksyms and get_addrs to trace_helpers.c selftests/bpf: skip recursive functions for kprobe_multi selftests/bpf: add benchmark testing for kprobe-multi-all tools/testing/selftests/bpf/bench.c | 4 + .../selftests/bpf/benchs/bench_trigger.c | 61 +++++ .../selftests/bpf/benchs/run_bench_trigger.sh | 4 +- .../bpf/prog_tests/kprobe_multi_test.c | 220 +--------------- .../selftests/bpf/progs/trigger_bench.c | 12 + tools/testing/selftests/bpf/trace_helpers.c | 234 ++++++++++++++++++ tools/testing/selftests/bpf/trace_helpers.h | 3 + 7 files changed, 319 insertions(+), 219 deletions(-) -- 2.51.0

1 week, 5 days

3
5
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[PATCH] selftests/bpf: Upon failures, exit with code 1 in test_xsk.sh

by Ricardo B. Marlière

Currently, even if some subtests fails, the end result will still yield "ok 1 selftests: bpf: test_xsk.sh". Fix it by exiting with 1 if there are any failures. Signed-off-by: Ricardo B. Marlière <rbm(a)suse.com> --- tools/testing/selftests/bpf/test_xsk.sh | 2 ++ 1 file changed, 2 insertions(+) diff --git a/tools/testing/selftests/bpf/test_xsk.sh b/tools/testing/selftests/bpf/test_xsk.sh index 65aafe0003db054e9dfd156092fed53b07be06a0..62db060298a4a3b4391ee4cfa50557cf4a62d3d5 100755 --- a/tools/testing/selftests/bpf/test_xsk.sh +++ b/tools/testing/selftests/bpf/test_xsk.sh @@ -241,4 +241,6 @@ done if [ $failures -eq 0 ]; then echo "All tests successful!" +else + exit 1 fi --- base-commit: 5b6d6fe1ca7b712c74f78426bb23c465fd34b322 change-id: 20250828-selftests-bpf-test_xsk_ret-1eb27dbac071 Best regards, -- Ricardo B. Marlière <rbm(a)suse.com>

1 week, 5 days

3
2
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[PATCH] selftests/bpf: Fix count write in testapp_xdp_metadata_copy()

by Ricardo B. Marlière

Commit 4b302092553c ("selftests/xsk: Add tail adjustment tests and support check") added a new global to xsk_xdp_progs.c, but left out the access in the testapp_xdp_metadata_copy() function. Since bpf_map_update_elem() will write to the whole bss section, it gets truncated. Fix by writing to skel_rx->bss->count directly. Fixes: 4b302092553c ("selftests/xsk: Add tail adjustment tests and support check") Signed-off-by: Ricardo B. Marlière <rbm(a)suse.com> --- tools/testing/selftests/bpf/xskxceiver.c | 14 +------------- 1 file changed, 1 insertion(+), 13 deletions(-) diff --git a/tools/testing/selftests/bpf/xskxceiver.c b/tools/testing/selftests/bpf/xskxceiver.c index a29de0713f19f05ef49a52e3824bb58a30565e87..352adc8df2d1cd777c823c5a89f1720ee043f342 100644 --- a/tools/testing/selftests/bpf/xskxceiver.c +++ b/tools/testing/selftests/bpf/xskxceiver.c @@ -2276,25 +2276,13 @@ static int testapp_xdp_metadata_copy(struct test_spec *test) { struct xsk_xdp_progs *skel_rx = test->ifobj_rx->xdp_progs; struct xsk_xdp_progs *skel_tx = test->ifobj_tx->xdp_progs; - struct bpf_map *data_map; - int count = 0; - int key = 0; test_spec_set_xdp_prog(test, skel_rx->progs.xsk_xdp_populate_metadata, skel_tx->progs.xsk_xdp_populate_metadata, skel_rx->maps.xsk, skel_tx->maps.xsk); test->ifobj_rx->use_metadata = true; - data_map = bpf_object__find_map_by_name(skel_rx->obj, "xsk_xdp_.bss"); - if (!data_map || !bpf_map__is_internal(data_map)) { - ksft_print_msg("Error: could not find bss section of XDP program\n"); - return TEST_FAILURE; - } - - if (bpf_map_update_elem(bpf_map__fd(data_map), &key, &count, BPF_ANY)) { - ksft_print_msg("Error: could not update count element\n"); - return TEST_FAILURE; - } + skel_rx->bss->count = 0; return testapp_validate_traffic(test); } --- base-commit: 5b6d6fe1ca7b712c74f78426bb23c465fd34b322 change-id: 20250829-selftests-bpf-xsk_regression_fix-674d292e4d2a Best regards, -- Ricardo B. Marlière <rbm(a)suse.com>

1 week, 5 days

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[PATCH net-next v2 0/4] mptcp: misc. features for v6.18

by Matthieu Baerts (NGI0)

This series contains 4 independent new features: - Patch 1: use HMAC-SHA256 library instead of open-coded HMAC. - Patch 2: selftests: check for unexpected fallback counter increments. - Patches 3-4: record subflows in RPS table, for aRFS support. Signed-off-by: Matthieu Baerts (NGI0) <matttbe(a)kernel.org> --- Changes in v2: - Drop previous patches 2 ("mptcp: make ADD_ADDR retransmission timeout adaptive") + 3 ("selftests: mptcp: remove add_addr_timeout settings"): They were introducing instabilities in the selftests. - Rebased. Other patches have not been modified. - Link to v1: https://lore.kernel.org/r/20250901-net-next-mptcp-misc-feat-6-18-v1-0-80ae8… --- Christoph Paasch (2): net: Add rfs_needed() helper mptcp: record subflows in RPS table Eric Biggers (1): mptcp: use HMAC-SHA256 library instead of open-coded HMAC Gang Yan (1): selftests: mptcp: add checks for fallback counters include/net/rps.h | 85 ++++++++++------ net/mptcp/crypto.c | 35 +------ net/mptcp/protocol.c | 21 ++++ tools/testing/selftests/net/mptcp/mptcp_join.sh | 123 ++++++++++++++++++++++++ 4 files changed, 202 insertions(+), 62 deletions(-) --- base-commit: cd8a4cfa6bb43a441901e82f5c222dddc75a18a3 change-id: 20250829-net-next-mptcp-misc-feat-6-18-722fa87a60f1 Best regards, -- Matthieu Baerts (NGI0) <matttbe(a)kernel.org>

1 week, 5 days

2
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[PATCH RESEND v4] selftests/tty: add TIOCSTI test suite

by Abhinav Saxena

TIOCSTI is a TTY ioctl command that allows inserting characters into the terminal input queue, making it appear as if the user typed those characters. This functionality has behavior that varies based on system configuration and process credentials. The dev.tty.legacy_tiocsti sysctl introduced in commit 83efeeeb3d04 ("tty: Allow TIOCSTI to be disabled") controls TIOCSTI usage. When disabled, TIOCSTI requires CAP_SYS_ADMIN capability. The current implementation checks the current process's credentials via capable(CAP_SYS_ADMIN), but does not validate against the file opener's credentials stored in file->f_cred. This creates different behavior when file descriptors are passed between processes via SCM_RIGHTS. Add a test suite with 16 test variants using fixture variants to verify TIOCSTI behavior when dev.tty.legacy_tiocsti is enabled/disabled: - Basic TIOCSTI tests (8 variants): Direct testing with different capability and controlling terminal combinations - FD passing tests (8 variants): Test behavior when file descriptors are passed between processes with different capabilities The FD passing tests document this behavior - some tests show different results than expected based on file opener credentials, demonstrating that TIOCSTI uses current process credentials rather than file opener credentials. The tests validate proper enforcement of the legacy_tiocsti sysctl. Test implementation uses openpty(3) with TIOCSCTTY for isolated PTY environments. See tty_ioctl(4) for details on TIOCSTI behavior and security requirements. Signed-off-by: Abhinav Saxena <xandfury(a)gmail.com> --- RESEND: add TTY/serial maintainers and linux-serial CCs. No code changes. - Link to orignal v4: https://lore.kernel.org/r/20250902-toicsti-bug-v4-1-e5c960e0b3d6@gmail.com Changes in v4: - Moved skip conditions and sysctl setup from TEST_F to FIXTURE_SETUP (Kees Cook) - Fixed fclose() error handling in set_legacy_tiocsti_setting (Kees Cook) - Extracted run_basic_tiocsti_test() and run_fdpass_tiocsti_test functions (Kees Cook) - Removed redundant sysctl restore logic from TEST_F (Kees Cook) - Simplified FIXTURE_TEARDOWN (Kees Cook) - Replace drop_to_nobody() to drop_all_privs() which should be more portable (Justin Stitt) - Link to v3: https://lore.kernel.org/r/20250730-toicsti-bug-v3-1-dd2dac97f27a@gmail.com Add selftests for TIOCSTI ioctl To run all tests: $ sudo ./tools/testing/selftests/tty/tty_tiocsti_test Test Results: - PASSED: 13/16 tests - Different behavior: 3/16 tests (documenting credential checking behavior) All tests validated using: - scripts/checkpatch.pl --strict (clean output) - Functional testing on kernel v6.16-rc2 Changes in v3: - Replaced all printf() calls with TH_LOG() for proper test logging (Kees Cook) - Added struct __test_metadata parameter to helper functions - Moved common legacy_tiocsti availability check to FIXTURE_SETUP() - Implemented sysctl modification/restoration in FIXTURE_SETUP/TEARDOWN - Used openpty() with TIOCSCTTY for reliable PTY testing environment - Fixed child/parent synchronization in FD passing tests - Replaced manual _exit(1) handling with proper ASSERT statements - Switched // comments to /* */ format throughout - Expanded to 16 test variants using fixture variants - Enhanced error handling and test reliability - Link to v2: https://lore.kernel.org/r/20250713-toicsti-bug-v2-1-b183787eea29@gmail.com - Link to v1: https://lore.kernel.org/r/20250622-toicsti-bug-v1-0-f374373b04b2@gmail.com References: - tty_ioctl(4) - documents TIOCSTI ioctl and capability requirements - openpty(3) - pseudo-terminal creation and management - commit 83efeeeb3d04 ("tty: Allow TIOCSTI to be disabled") - Documentation/security/credentials.rst - https://github.com/KSPP/linux/issues/156 - https://lore.kernel.org/linux-hardening/Y0m9l52AKmw6Yxi1@hostpad/ - drivers/tty/Kconfig - Documentation/driver-api/tty/ --- tools/testing/selftests/tty/Makefile | 6 +- tools/testing/selftests/tty/config | 1 + tools/testing/selftests/tty/tty_tiocsti_test.c | 650 +++++++++++++++++++++++++ 3 files changed, 656 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/tty/Makefile b/tools/testing/selftests/tty/Makefile index 50d7027b2ae3fb495dd1c0684363fa8f426be42c..7f6fbe5a0cd5663310e334d9d068b21dab9136ec 100644 --- a/tools/testing/selftests/tty/Makefile +++ b/tools/testing/selftests/tty/Makefile @@ -1,5 +1,9 @@ # SPDX-License-Identifier: GPL-2.0 CFLAGS = -O2 -Wall -TEST_GEN_PROGS := tty_tstamp_update +TEST_GEN_PROGS := tty_tstamp_update tty_tiocsti_test +LDLIBS += -lcap include ../lib.mk + +# Add libcap for TIOCSTI test +$(OUTPUT)/tty_tiocsti_test: LDLIBS += -lcap diff --git a/tools/testing/selftests/tty/config b/tools/testing/selftests/tty/config new file mode 100644 index 0000000000000000000000000000000000000000..c6373aba66366c82435bb26c019eb360eb6310eb --- /dev/null +++ b/tools/testing/selftests/tty/config @@ -0,0 +1 @@ +CONFIG_LEGACY_TIOCSTI=y diff --git a/tools/testing/selftests/tty/tty_tiocsti_test.c b/tools/testing/selftests/tty/tty_tiocsti_test.c new file mode 100644 index 0000000000000000000000000000000000000000..5e767e6cb3ef8f05c5430eb0fcc792064c446c03 --- /dev/null +++ b/tools/testing/selftests/tty/tty_tiocsti_test.c @@ -0,0 +1,650 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * TTY Tests - TIOCSTI + * + * Copyright © 2025 Abhinav Saxena <xandfury(a)gmail.com> + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <fcntl.h> +#include <sys/ioctl.h> +#include <errno.h> +#include <stdbool.h> +#include <string.h> +#include <sys/socket.h> +#include <sys/wait.h> +#include <pwd.h> +#include <termios.h> +#include <grp.h> +#include <sys/capability.h> +#include <sys/prctl.h> +#include <pty.h> +#include <utmp.h> + +#include "../kselftest_harness.h" + +enum test_type { + TEST_PTY_TIOCSTI_BASIC, + TEST_PTY_TIOCSTI_FD_PASSING, + /* other tests cases such as serial may be added. */ +}; + +/* + * Test Strategy: + * - Basic tests: Use PTY with/without TIOCSCTTY (controlling terminal for + * current process) + * - FD passing tests: Child creates PTY, parent receives FD (demonstrates + * security issue) + * + * SECURITY VULNERABILITY DEMONSTRATION: + * FD passing tests show that TIOCSTI uses CURRENT process credentials, not + * opener credentials. This means privileged processes can be given FDs from + * unprivileged processes and successfully perform TIOCSTI operations that the + * unprivileged process couldn't do directly. + * + * Attack scenario: + * 1. Unprivileged process opens TTY (direct TIOCSTI fails due to lack of + * privileges) + * 2. Unprivileged process passes FD to privileged process via SCM_RIGHTS + * 3. Privileged process can use TIOCSTI on the FD (succeeds due to its + * privileges) + * 4. Result: Effective privilege escalation via file descriptor passing + * + * This matches the kernel logic in tiocsti(): + * 1. if (!tty_legacy_tiocsti && !capable(CAP_SYS_ADMIN)) return -EIO; + * 2. if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN)) + * return -EPERM; + * Note: Both checks use capable() on CURRENT process, not FD opener! + * + * If the file credentials were also checked along with the capable() checks + * then the results for FD pass tests would be consistent with the basic tests. + */ + +FIXTURE(tiocsti) +{ + int pty_master_fd; /* PTY - for basic tests */ + int pty_slave_fd; + bool has_pty; + bool initial_cap_sys_admin; + int original_legacy_tiocsti_setting; + bool can_modify_sysctl; +}; + +FIXTURE_VARIANT(tiocsti) +{ + const enum test_type test_type; + const bool controlling_tty; /* true=current->signal->tty == tty */ + const int legacy_tiocsti; /* 0=restricted, 1=permissive */ + const bool requires_cap; /* true=with CAP_SYS_ADMIN, false=without */ + const int expected_success; /* 0=success, -EIO/-EPERM=specific error */ +}; + +/* + * Tests Controlling Terminal Variants (current->signal->tty == tty) + * + * TIOCSTI Test Matrix: + * + * | legacy_tiocsti | CAP_SYS_ADMIN | Expected Result | Error | + * |----------------|---------------|-----------------|-------| + * | 1 (permissive) | true | SUCCESS | - | + * | 1 (permissive) | false | SUCCESS | - | + * | 0 (restricted) | true | SUCCESS | - | + * | 0 (restricted) | false | FAILURE | -EIO | + */ + +/* clang-format off */ +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, /* FAILURE: legacy restriction */ +}; /* clang-format on */ + +/* + * Note for FD Passing Test Variants + * Since we're testing the scenario where an unprivileged process pass an FD + * to a privileged one, .requires_cap here means the caps of the child process. + * Not the parent; parent would always be privileged. + */ + +/* clang-format off */ +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, +}; /* clang-format on */ + +/* + * Non-Controlling Terminal Variants (current->signal->tty != tty) + * + * TIOCSTI Test Matrix: + * + * | legacy_tiocsti | CAP_SYS_ADMIN | Expected Result | Error | + * |----------------|---------------|-----------------|-------| + * | 1 (permissive) | true | SUCCESS | - | + * | 1 (permissive) | false | FAILURE | -EPERM| + * | 0 (restricted) | true | SUCCESS | - | + * | 0 (restricted) | false | FAILURE | -EIO | + */ + +/* clang-format off */ +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = -EPERM, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = -EPERM, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, +}; /* clang-format on */ + +/* Helper function to send FD via SCM_RIGHTS */ +static int send_fd_via_socket(int socket_fd, int fd_to_send) +{ + struct msghdr msg = { 0 }; + struct cmsghdr *cmsg; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + char dummy_data = 'F'; + struct iovec iov = { .iov_base = &dummy_data, .iov_len = 1 }; + + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + + memcpy(CMSG_DATA(cmsg), &fd_to_send, sizeof(int)); + + return sendmsg(socket_fd, &msg, 0) < 0 ? -1 : 0; +} + +/* Helper function to receive FD via SCM_RIGHTS */ +static int recv_fd_via_socket(int socket_fd) +{ + struct msghdr msg = { 0 }; + struct cmsghdr *cmsg; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + char dummy_data; + struct iovec iov = { .iov_base = &dummy_data, .iov_len = 1 }; + int received_fd = -1; + + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + if (recvmsg(socket_fd, &msg, 0) < 0) + return -1; + + for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { + if (cmsg->cmsg_level == SOL_SOCKET && + cmsg->cmsg_type == SCM_RIGHTS) { + memcpy(&received_fd, CMSG_DATA(cmsg), sizeof(int)); + break; + } + } + + return received_fd; +} + +static inline bool has_cap_sys_admin(void) +{ + cap_t caps = cap_get_proc(); + + if (!caps) + return false; + + cap_flag_value_t cap_val; + bool has_cap = (cap_get_flag(caps, CAP_SYS_ADMIN, CAP_EFFECTIVE, + &cap_val) == 0) && + (cap_val == CAP_SET); + + cap_free(caps); + return has_cap; +} + +/* + * Switch to non-root user and clear all capabilities + */ +static inline bool drop_all_privs(struct __test_metadata *_metadata) +{ + /* Drop supplementary groups */ + ASSERT_EQ(setgroups(0, NULL), 0); + + /* Switch to non-root user */ + ASSERT_EQ(setgid(1000), 0); + ASSERT_EQ(setuid(1000), 0); + + /* Clear all capabilities */ + cap_t empty = cap_init(); + + ASSERT_NE(empty, NULL); + ASSERT_EQ(cap_set_proc(empty), 0); + cap_free(empty); + + /* Prevent privilege regain */ + ASSERT_EQ(prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0), 0); + + /* Verify privilege drop */ + ASSERT_FALSE(has_cap_sys_admin()); + return true; +} + +static inline int get_legacy_tiocsti_setting(struct __test_metadata *_metadata) +{ + FILE *fp; + int value = -1; + + fp = fopen("/proc/sys/dev/tty/legacy_tiocsti", "r"); + if (!fp) { + /* legacy_tiocsti sysctl not available (kernel < 6.2) */ + return -1; + } + + if (fscanf(fp, "%d", &value) == 1 && fclose(fp) == 0) { + if (value < 0 || value > 1) + value = -1; /* Invalid value */ + } else { + value = -1; /* Failed to parse */ + } + + return value; +} + +static inline bool set_legacy_tiocsti_setting(struct __test_metadata *_metadata, + int value) +{ + FILE *fp; + bool success = false; + + /* Sanity-check the value */ + ASSERT_GE(value, 0); + ASSERT_LE(value, 1); + + /* + * Try to open for writing; if we lack permission, return false so + * the test harness will skip variants that need to change it + */ + fp = fopen("/proc/sys/dev/tty/legacy_tiocsti", "w"); + if (!fp) + return false; + + /* Write the new setting */ + if (fprintf(fp, "%d\n", value) > 0 && fclose(fp) == 0) + success = true; + else + TH_LOG("Failed to write legacy_tiocsti: %s", strerror(errno)); + + return success; +} + +/* + * TIOCSTI injection test function + * @tty_fd: TTY slave file descriptor to test TIOCSTI on + * Returns: 0 on success, -errno on failure + */ +static inline int test_tiocsti_injection(struct __test_metadata *_metadata, + int tty_fd) +{ + int ret; + char inject_char = 'V'; + + errno = 0; + ret = ioctl(tty_fd, TIOCSTI, &inject_char); + return ret == 0 ? 0 : -errno; +} + +/* + * Child process: test TIOCSTI directly with capability/controlling + * terminal setup + */ +static void run_basic_tiocsti_test(struct __test_metadata *_metadata, + FIXTURE_DATA(tiocsti) * self, + const FIXTURE_VARIANT(tiocsti) * variant) +{ + /* Handle capability requirements */ + if (self->initial_cap_sys_admin && !variant->requires_cap) + ASSERT_TRUE(drop_all_privs(_metadata)); + + if (variant->controlling_tty) { + /* + * Create new session and set PTY as + * controlling terminal + */ + pid_t sid = setsid(); + + ASSERT_GE(sid, 0); + ASSERT_EQ(ioctl(self->pty_slave_fd, TIOCSCTTY, 0), 0); + } + + /* + * Validate test environment setup and verify final + * capability state matches expectation + * after potential drop. + */ + ASSERT_TRUE(self->has_pty); + ASSERT_EQ(has_cap_sys_admin(), variant->requires_cap); + + /* Test TIOCSTI and validate result */ + int result = test_tiocsti_injection(_metadata, self->pty_slave_fd); + + /* Check against expected result from variant */ + EXPECT_EQ(result, variant->expected_success); + _exit(0); +} + +/* + * Child process: create PTY and then pass FD to parent via SCM_RIGHTS + */ +static void run_fdpass_tiocsti_test(struct __test_metadata *_metadata, + const FIXTURE_VARIANT(tiocsti) * variant, + int sockfd) +{ + signal(SIGHUP, SIG_IGN); + + /* Handle privilege dropping */ + if (!variant->requires_cap && has_cap_sys_admin()) + ASSERT_TRUE(drop_all_privs(_metadata)); + + /* Create child's PTY */ + int child_master_fd, child_slave_fd; + + ASSERT_EQ(openpty(&child_master_fd, &child_slave_fd, NULL, NULL, NULL), + 0); + + if (variant->controlling_tty) { + pid_t sid = setsid(); + + ASSERT_GE(sid, 0); + ASSERT_EQ(ioctl(child_slave_fd, TIOCSCTTY, 0), 0); + } + + /* Test child's direct TIOCSTI for reference */ + int direct_result = test_tiocsti_injection(_metadata, child_slave_fd); + + EXPECT_EQ(direct_result, variant->expected_success); + + /* Send FD to parent */ + ASSERT_EQ(send_fd_via_socket(sockfd, child_slave_fd), 0); + + /* Wait for parent completion signal */ + char sync_byte; + ssize_t bytes_read = read(sockfd, &sync_byte, 1); + + ASSERT_EQ(bytes_read, 1); + + close(child_master_fd); + close(child_slave_fd); + close(sockfd); + _exit(0); +} + +FIXTURE_SETUP(tiocsti) +{ + /* Create PTY pair for basic tests */ + self->has_pty = (openpty(&self->pty_master_fd, &self->pty_slave_fd, + NULL, NULL, NULL) == 0); + if (!self->has_pty) { + self->pty_master_fd = -1; + self->pty_slave_fd = -1; + } + + self->initial_cap_sys_admin = has_cap_sys_admin(); + self->original_legacy_tiocsti_setting = + get_legacy_tiocsti_setting(_metadata); + + if (self->original_legacy_tiocsti_setting < 0) + SKIP(return, + "legacy_tiocsti sysctl not available (kernel < 6.2)"); + + /* Common skip conditions */ + if (variant->test_type == TEST_PTY_TIOCSTI_BASIC && !self->has_pty) + SKIP(return, "PTY not available for controlling terminal test"); + + if (variant->test_type == TEST_PTY_TIOCSTI_FD_PASSING && + !self->initial_cap_sys_admin) + SKIP(return, "FD Pass tests require CAP_SYS_ADMIN"); + + if (variant->requires_cap && !self->initial_cap_sys_admin) + SKIP(return, "Test requires initial CAP_SYS_ADMIN"); + + /* Test if we can modify the sysctl (requires appropriate privileges) */ + self->can_modify_sysctl = set_legacy_tiocsti_setting( + _metadata, self->original_legacy_tiocsti_setting); + + /* Sysctl setup based on variant */ + if (self->can_modify_sysctl && + self->original_legacy_tiocsti_setting != variant->legacy_tiocsti) { + if (!set_legacy_tiocsti_setting(_metadata, + variant->legacy_tiocsti)) + SKIP(return, "Failed to set legacy_tiocsti sysctl"); + + } else if (!self->can_modify_sysctl && + self->original_legacy_tiocsti_setting != + variant->legacy_tiocsti) + SKIP(return, "legacy_tiocsti setting mismatch"); +} + +FIXTURE_TEARDOWN(tiocsti) +{ + /* + * Backup restoration - + * each test should restore its own sysctl changes + */ + if (self->can_modify_sysctl) { + int current_value = get_legacy_tiocsti_setting(_metadata); + + if (current_value != self->original_legacy_tiocsti_setting) { + TH_LOG("Backup: Restoring legacy_tiocsti from %d to %d", + current_value, + self->original_legacy_tiocsti_setting); + set_legacy_tiocsti_setting( + _metadata, + self->original_legacy_tiocsti_setting); + } + } + + if (self->has_pty) { + if (self->pty_master_fd >= 0) + close(self->pty_master_fd); + if (self->pty_slave_fd >= 0) + close(self->pty_slave_fd); + } +} + +TEST_F(tiocsti, test) +{ + int status; + pid_t child_pid; + + if (variant->test_type == TEST_PTY_TIOCSTI_BASIC) { + /* ===== BASIC TIOCSTI TEST ===== */ + child_pid = fork(); + ASSERT_GE(child_pid, 0); + + /* Perform the actual test in the child process */ + if (child_pid == 0) + run_basic_tiocsti_test(_metadata, self, variant); + + } else { + /* ===== FD PASSING SECURITY TEST ===== */ + int sockpair[2]; + + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sockpair), 0); + + child_pid = fork(); + ASSERT_GE(child_pid, 0); + + if (child_pid == 0) { + /* Child process - create PTY and send FD */ + close(sockpair[0]); + run_fdpass_tiocsti_test(_metadata, variant, + sockpair[1]); + } + + /* Parent process - receive FD and test TIOCSTI */ + close(sockpair[1]); + + int received_fd = recv_fd_via_socket(sockpair[0]); + + ASSERT_GE(received_fd, 0); + + bool parent_has_cap = self->initial_cap_sys_admin; + + TH_LOG("=== TIOCSTI FD Passing Test Context ==="); + TH_LOG("legacy_tiocsti: %d, Parent CAP_SYS_ADMIN: %s, Child: %s", + variant->legacy_tiocsti, parent_has_cap ? "yes" : "no", + variant->requires_cap ? "kept" : "dropped"); + + /* SECURITY TEST: Try TIOCSTI with FD opened by child */ + int result = test_tiocsti_injection(_metadata, received_fd); + + /* Log security concern if demonstrated */ + if (result == 0 && !variant->requires_cap) { + TH_LOG("*** SECURITY CONCERN DEMONSTRATED ***"); + TH_LOG("Privileged parent can use TIOCSTI on FD from unprivileged child"); + TH_LOG("This shows current process credentials are used, not opener credentials"); + } + + EXPECT_EQ(result, variant->expected_success) + { + TH_LOG("FD passing: expected error %d, got %d", + variant->expected_success, result); + } + + /* Signal child completion */ + char sync_byte = 'D'; + ssize_t bytes_written = write(sockpair[0], &sync_byte, 1); + + ASSERT_EQ(bytes_written, 1); + + close(received_fd); + close(sockpair[0]); + } + + /* Common child process cleanup for both test types */ + ASSERT_EQ(waitpid(child_pid, &status, 0), child_pid); + + if (WIFSIGNALED(status)) { + TH_LOG("Child terminated by signal %d", WTERMSIG(status)); + ASSERT_FALSE(WIFSIGNALED(status)) + { + TH_LOG("Child process failed assertion"); + } + } else { + EXPECT_EQ(WEXITSTATUS(status), 0); + } +} + +TEST_HARNESS_MAIN --- base-commit: e6b9dce0aeeb91dfc0974ab87f02454e24566182 change-id: 20250618-toicsti-bug-7822b8e94a32 Best regards, -- Abhinav Saxena <xandfury(a)gmail.com>

1 week, 5 days

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[PATCH v4] selftests/tty: add TIOCSTI test suite

by Abhinav Saxena

TIOCSTI is a TTY ioctl command that allows inserting characters into the terminal input queue, making it appear as if the user typed those characters. This functionality has behavior that varies based on system configuration and process credentials. The dev.tty.legacy_tiocsti sysctl introduced in commit 83efeeeb3d04 ("tty: Allow TIOCSTI to be disabled") controls TIOCSTI usage. When disabled, TIOCSTI requires CAP_SYS_ADMIN capability. The current implementation checks the current process's credentials via capable(CAP_SYS_ADMIN), but does not validate against the file opener's credentials stored in file->f_cred. This creates different behavior when file descriptors are passed between processes via SCM_RIGHTS. Add a test suite with 16 test variants using fixture variants to verify TIOCSTI behavior when dev.tty.legacy_tiocsti is enabled/disabled: - Basic TIOCSTI tests (8 variants): Direct testing with different capability and controlling terminal combinations - FD passing tests (8 variants): Test behavior when file descriptors are passed between processes with different capabilities The FD passing tests document this behavior - some tests show different results than expected based on file opener credentials, demonstrating that TIOCSTI uses current process credentials rather than file opener credentials. The tests validate proper enforcement of the legacy_tiocsti sysctl. Test implementation uses openpty(3) with TIOCSCTTY for isolated PTY environments. See tty_ioctl(4) for details on TIOCSTI behavior and security requirements. Signed-off-by: Abhinav Saxena <xandfury(a)gmail.com> --- Changes in v4: - Moved skip conditions and sysctl setup from TEST_F to FIXTURE_SETUP (Kees Cook) - Fixed fclose() error handling in set_legacy_tiocsti_setting (Kees Cook) - Extracted run_basic_tiocsti_test() and run_fdpass_tiocsti_test functions (Kees Cook) - Removed redundant sysctl restore logic from TEST_F (Kees Cook) - Simplified FIXTURE_TEARDOWN (Kees Cook) - Replace drop_to_nobody() to drop_all_privs() which should be more portable (Justin Stitt) - Link to v3: https://lore.kernel.org/r/20250730-toicsti-bug-v3-1-dd2dac97f27a@gmail.com Add selftests for TIOCSTI ioctl To run all tests: $ sudo ./tools/testing/selftests/tty/tty_tiocsti_test Test Results: - PASSED: 13/16 tests - Different behavior: 3/16 tests (documenting credential checking behavior) All tests validated using: - scripts/checkpatch.pl --strict (clean output) - Functional testing on kernel v6.16-rc2 Changes in v3: - Replaced all printf() calls with TH_LOG() for proper test logging (Kees Cook) - Added struct __test_metadata parameter to helper functions - Moved common legacy_tiocsti availability check to FIXTURE_SETUP() - Implemented sysctl modification/restoration in FIXTURE_SETUP/TEARDOWN - Used openpty() with TIOCSCTTY for reliable PTY testing environment - Fixed child/parent synchronization in FD passing tests - Replaced manual _exit(1) handling with proper ASSERT statements - Switched // comments to /* */ format throughout - Expanded to 16 test variants using fixture variants - Enhanced error handling and test reliability - Link to v2: https://lore.kernel.org/r/20250713-toicsti-bug-v2-1-b183787eea29@gmail.com - Link to v1: https://lore.kernel.org/r/20250622-toicsti-bug-v1-0-f374373b04b2@gmail.com References: - tty_ioctl(4) - documents TIOCSTI ioctl and capability requirements - openpty(3) - pseudo-terminal creation and management - commit 83efeeeb3d04 ("tty: Allow TIOCSTI to be disabled") - Documentation/security/credentials.rst - https://github.com/KSPP/linux/issues/156 - https://lore.kernel.org/linux-hardening/Y0m9l52AKmw6Yxi1@hostpad/ - drivers/tty/Kconfig - Documentation/driver-api/tty/ --- tools/testing/selftests/tty/Makefile | 6 +- tools/testing/selftests/tty/config | 1 + tools/testing/selftests/tty/tty_tiocsti_test.c | 650 +++++++++++++++++++++++++ 3 files changed, 656 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/tty/Makefile b/tools/testing/selftests/tty/Makefile index 50d7027b2ae3fb495dd1c0684363fa8f426be42c..7f6fbe5a0cd5663310e334d9d068b21dab9136ec 100644 --- a/tools/testing/selftests/tty/Makefile +++ b/tools/testing/selftests/tty/Makefile @@ -1,5 +1,9 @@ # SPDX-License-Identifier: GPL-2.0 CFLAGS = -O2 -Wall -TEST_GEN_PROGS := tty_tstamp_update +TEST_GEN_PROGS := tty_tstamp_update tty_tiocsti_test +LDLIBS += -lcap include ../lib.mk + +# Add libcap for TIOCSTI test +$(OUTPUT)/tty_tiocsti_test: LDLIBS += -lcap diff --git a/tools/testing/selftests/tty/config b/tools/testing/selftests/tty/config new file mode 100644 index 0000000000000000000000000000000000000000..c6373aba66366c82435bb26c019eb360eb6310eb --- /dev/null +++ b/tools/testing/selftests/tty/config @@ -0,0 +1 @@ +CONFIG_LEGACY_TIOCSTI=y diff --git a/tools/testing/selftests/tty/tty_tiocsti_test.c b/tools/testing/selftests/tty/tty_tiocsti_test.c new file mode 100644 index 0000000000000000000000000000000000000000..5e767e6cb3ef8f05c5430eb0fcc792064c446c03 --- /dev/null +++ b/tools/testing/selftests/tty/tty_tiocsti_test.c @@ -0,0 +1,650 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * TTY Tests - TIOCSTI + * + * Copyright © 2025 Abhinav Saxena <xandfury(a)gmail.com> + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <fcntl.h> +#include <sys/ioctl.h> +#include <errno.h> +#include <stdbool.h> +#include <string.h> +#include <sys/socket.h> +#include <sys/wait.h> +#include <pwd.h> +#include <termios.h> +#include <grp.h> +#include <sys/capability.h> +#include <sys/prctl.h> +#include <pty.h> +#include <utmp.h> + +#include "../kselftest_harness.h" + +enum test_type { + TEST_PTY_TIOCSTI_BASIC, + TEST_PTY_TIOCSTI_FD_PASSING, + /* other tests cases such as serial may be added. */ +}; + +/* + * Test Strategy: + * - Basic tests: Use PTY with/without TIOCSCTTY (controlling terminal for + * current process) + * - FD passing tests: Child creates PTY, parent receives FD (demonstrates + * security issue) + * + * SECURITY VULNERABILITY DEMONSTRATION: + * FD passing tests show that TIOCSTI uses CURRENT process credentials, not + * opener credentials. This means privileged processes can be given FDs from + * unprivileged processes and successfully perform TIOCSTI operations that the + * unprivileged process couldn't do directly. + * + * Attack scenario: + * 1. Unprivileged process opens TTY (direct TIOCSTI fails due to lack of + * privileges) + * 2. Unprivileged process passes FD to privileged process via SCM_RIGHTS + * 3. Privileged process can use TIOCSTI on the FD (succeeds due to its + * privileges) + * 4. Result: Effective privilege escalation via file descriptor passing + * + * This matches the kernel logic in tiocsti(): + * 1. if (!tty_legacy_tiocsti && !capable(CAP_SYS_ADMIN)) return -EIO; + * 2. if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN)) + * return -EPERM; + * Note: Both checks use capable() on CURRENT process, not FD opener! + * + * If the file credentials were also checked along with the capable() checks + * then the results for FD pass tests would be consistent with the basic tests. + */ + +FIXTURE(tiocsti) +{ + int pty_master_fd; /* PTY - for basic tests */ + int pty_slave_fd; + bool has_pty; + bool initial_cap_sys_admin; + int original_legacy_tiocsti_setting; + bool can_modify_sysctl; +}; + +FIXTURE_VARIANT(tiocsti) +{ + const enum test_type test_type; + const bool controlling_tty; /* true=current->signal->tty == tty */ + const int legacy_tiocsti; /* 0=restricted, 1=permissive */ + const bool requires_cap; /* true=with CAP_SYS_ADMIN, false=without */ + const int expected_success; /* 0=success, -EIO/-EPERM=specific error */ +}; + +/* + * Tests Controlling Terminal Variants (current->signal->tty == tty) + * + * TIOCSTI Test Matrix: + * + * | legacy_tiocsti | CAP_SYS_ADMIN | Expected Result | Error | + * |----------------|---------------|-----------------|-------| + * | 1 (permissive) | true | SUCCESS | - | + * | 1 (permissive) | false | SUCCESS | - | + * | 0 (restricted) | true | SUCCESS | - | + * | 0 (restricted) | false | FAILURE | -EIO | + */ + +/* clang-format off */ +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, /* FAILURE: legacy restriction */ +}; /* clang-format on */ + +/* + * Note for FD Passing Test Variants + * Since we're testing the scenario where an unprivileged process pass an FD + * to a privileged one, .requires_cap here means the caps of the child process. + * Not the parent; parent would always be privileged. + */ + +/* clang-format off */ +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, +}; /* clang-format on */ + +/* + * Non-Controlling Terminal Variants (current->signal->tty != tty) + * + * TIOCSTI Test Matrix: + * + * | legacy_tiocsti | CAP_SYS_ADMIN | Expected Result | Error | + * |----------------|---------------|-----------------|-------| + * | 1 (permissive) | true | SUCCESS | - | + * | 1 (permissive) | false | FAILURE | -EPERM| + * | 0 (restricted) | true | SUCCESS | - | + * | 0 (restricted) | false | FAILURE | -EIO | + */ + +/* clang-format off */ +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = -EPERM, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = -EPERM, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, +}; /* clang-format on */ + +/* Helper function to send FD via SCM_RIGHTS */ +static int send_fd_via_socket(int socket_fd, int fd_to_send) +{ + struct msghdr msg = { 0 }; + struct cmsghdr *cmsg; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + char dummy_data = 'F'; + struct iovec iov = { .iov_base = &dummy_data, .iov_len = 1 }; + + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + + memcpy(CMSG_DATA(cmsg), &fd_to_send, sizeof(int)); + + return sendmsg(socket_fd, &msg, 0) < 0 ? -1 : 0; +} + +/* Helper function to receive FD via SCM_RIGHTS */ +static int recv_fd_via_socket(int socket_fd) +{ + struct msghdr msg = { 0 }; + struct cmsghdr *cmsg; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + char dummy_data; + struct iovec iov = { .iov_base = &dummy_data, .iov_len = 1 }; + int received_fd = -1; + + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + if (recvmsg(socket_fd, &msg, 0) < 0) + return -1; + + for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { + if (cmsg->cmsg_level == SOL_SOCKET && + cmsg->cmsg_type == SCM_RIGHTS) { + memcpy(&received_fd, CMSG_DATA(cmsg), sizeof(int)); + break; + } + } + + return received_fd; +} + +static inline bool has_cap_sys_admin(void) +{ + cap_t caps = cap_get_proc(); + + if (!caps) + return false; + + cap_flag_value_t cap_val; + bool has_cap = (cap_get_flag(caps, CAP_SYS_ADMIN, CAP_EFFECTIVE, + &cap_val) == 0) && + (cap_val == CAP_SET); + + cap_free(caps); + return has_cap; +} + +/* + * Switch to non-root user and clear all capabilities + */ +static inline bool drop_all_privs(struct __test_metadata *_metadata) +{ + /* Drop supplementary groups */ + ASSERT_EQ(setgroups(0, NULL), 0); + + /* Switch to non-root user */ + ASSERT_EQ(setgid(1000), 0); + ASSERT_EQ(setuid(1000), 0); + + /* Clear all capabilities */ + cap_t empty = cap_init(); + + ASSERT_NE(empty, NULL); + ASSERT_EQ(cap_set_proc(empty), 0); + cap_free(empty); + + /* Prevent privilege regain */ + ASSERT_EQ(prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0), 0); + + /* Verify privilege drop */ + ASSERT_FALSE(has_cap_sys_admin()); + return true; +} + +static inline int get_legacy_tiocsti_setting(struct __test_metadata *_metadata) +{ + FILE *fp; + int value = -1; + + fp = fopen("/proc/sys/dev/tty/legacy_tiocsti", "r"); + if (!fp) { + /* legacy_tiocsti sysctl not available (kernel < 6.2) */ + return -1; + } + + if (fscanf(fp, "%d", &value) == 1 && fclose(fp) == 0) { + if (value < 0 || value > 1) + value = -1; /* Invalid value */ + } else { + value = -1; /* Failed to parse */ + } + + return value; +} + +static inline bool set_legacy_tiocsti_setting(struct __test_metadata *_metadata, + int value) +{ + FILE *fp; + bool success = false; + + /* Sanity-check the value */ + ASSERT_GE(value, 0); + ASSERT_LE(value, 1); + + /* + * Try to open for writing; if we lack permission, return false so + * the test harness will skip variants that need to change it + */ + fp = fopen("/proc/sys/dev/tty/legacy_tiocsti", "w"); + if (!fp) + return false; + + /* Write the new setting */ + if (fprintf(fp, "%d\n", value) > 0 && fclose(fp) == 0) + success = true; + else + TH_LOG("Failed to write legacy_tiocsti: %s", strerror(errno)); + + return success; +} + +/* + * TIOCSTI injection test function + * @tty_fd: TTY slave file descriptor to test TIOCSTI on + * Returns: 0 on success, -errno on failure + */ +static inline int test_tiocsti_injection(struct __test_metadata *_metadata, + int tty_fd) +{ + int ret; + char inject_char = 'V'; + + errno = 0; + ret = ioctl(tty_fd, TIOCSTI, &inject_char); + return ret == 0 ? 0 : -errno; +} + +/* + * Child process: test TIOCSTI directly with capability/controlling + * terminal setup + */ +static void run_basic_tiocsti_test(struct __test_metadata *_metadata, + FIXTURE_DATA(tiocsti) * self, + const FIXTURE_VARIANT(tiocsti) * variant) +{ + /* Handle capability requirements */ + if (self->initial_cap_sys_admin && !variant->requires_cap) + ASSERT_TRUE(drop_all_privs(_metadata)); + + if (variant->controlling_tty) { + /* + * Create new session and set PTY as + * controlling terminal + */ + pid_t sid = setsid(); + + ASSERT_GE(sid, 0); + ASSERT_EQ(ioctl(self->pty_slave_fd, TIOCSCTTY, 0), 0); + } + + /* + * Validate test environment setup and verify final + * capability state matches expectation + * after potential drop. + */ + ASSERT_TRUE(self->has_pty); + ASSERT_EQ(has_cap_sys_admin(), variant->requires_cap); + + /* Test TIOCSTI and validate result */ + int result = test_tiocsti_injection(_metadata, self->pty_slave_fd); + + /* Check against expected result from variant */ + EXPECT_EQ(result, variant->expected_success); + _exit(0); +} + +/* + * Child process: create PTY and then pass FD to parent via SCM_RIGHTS + */ +static void run_fdpass_tiocsti_test(struct __test_metadata *_metadata, + const FIXTURE_VARIANT(tiocsti) * variant, + int sockfd) +{ + signal(SIGHUP, SIG_IGN); + + /* Handle privilege dropping */ + if (!variant->requires_cap && has_cap_sys_admin()) + ASSERT_TRUE(drop_all_privs(_metadata)); + + /* Create child's PTY */ + int child_master_fd, child_slave_fd; + + ASSERT_EQ(openpty(&child_master_fd, &child_slave_fd, NULL, NULL, NULL), + 0); + + if (variant->controlling_tty) { + pid_t sid = setsid(); + + ASSERT_GE(sid, 0); + ASSERT_EQ(ioctl(child_slave_fd, TIOCSCTTY, 0), 0); + } + + /* Test child's direct TIOCSTI for reference */ + int direct_result = test_tiocsti_injection(_metadata, child_slave_fd); + + EXPECT_EQ(direct_result, variant->expected_success); + + /* Send FD to parent */ + ASSERT_EQ(send_fd_via_socket(sockfd, child_slave_fd), 0); + + /* Wait for parent completion signal */ + char sync_byte; + ssize_t bytes_read = read(sockfd, &sync_byte, 1); + + ASSERT_EQ(bytes_read, 1); + + close(child_master_fd); + close(child_slave_fd); + close(sockfd); + _exit(0); +} + +FIXTURE_SETUP(tiocsti) +{ + /* Create PTY pair for basic tests */ + self->has_pty = (openpty(&self->pty_master_fd, &self->pty_slave_fd, + NULL, NULL, NULL) == 0); + if (!self->has_pty) { + self->pty_master_fd = -1; + self->pty_slave_fd = -1; + } + + self->initial_cap_sys_admin = has_cap_sys_admin(); + self->original_legacy_tiocsti_setting = + get_legacy_tiocsti_setting(_metadata); + + if (self->original_legacy_tiocsti_setting < 0) + SKIP(return, + "legacy_tiocsti sysctl not available (kernel < 6.2)"); + + /* Common skip conditions */ + if (variant->test_type == TEST_PTY_TIOCSTI_BASIC && !self->has_pty) + SKIP(return, "PTY not available for controlling terminal test"); + + if (variant->test_type == TEST_PTY_TIOCSTI_FD_PASSING && + !self->initial_cap_sys_admin) + SKIP(return, "FD Pass tests require CAP_SYS_ADMIN"); + + if (variant->requires_cap && !self->initial_cap_sys_admin) + SKIP(return, "Test requires initial CAP_SYS_ADMIN"); + + /* Test if we can modify the sysctl (requires appropriate privileges) */ + self->can_modify_sysctl = set_legacy_tiocsti_setting( + _metadata, self->original_legacy_tiocsti_setting); + + /* Sysctl setup based on variant */ + if (self->can_modify_sysctl && + self->original_legacy_tiocsti_setting != variant->legacy_tiocsti) { + if (!set_legacy_tiocsti_setting(_metadata, + variant->legacy_tiocsti)) + SKIP(return, "Failed to set legacy_tiocsti sysctl"); + + } else if (!self->can_modify_sysctl && + self->original_legacy_tiocsti_setting != + variant->legacy_tiocsti) + SKIP(return, "legacy_tiocsti setting mismatch"); +} + +FIXTURE_TEARDOWN(tiocsti) +{ + /* + * Backup restoration - + * each test should restore its own sysctl changes + */ + if (self->can_modify_sysctl) { + int current_value = get_legacy_tiocsti_setting(_metadata); + + if (current_value != self->original_legacy_tiocsti_setting) { + TH_LOG("Backup: Restoring legacy_tiocsti from %d to %d", + current_value, + self->original_legacy_tiocsti_setting); + set_legacy_tiocsti_setting( + _metadata, + self->original_legacy_tiocsti_setting); + } + } + + if (self->has_pty) { + if (self->pty_master_fd >= 0) + close(self->pty_master_fd); + if (self->pty_slave_fd >= 0) + close(self->pty_slave_fd); + } +} + +TEST_F(tiocsti, test) +{ + int status; + pid_t child_pid; + + if (variant->test_type == TEST_PTY_TIOCSTI_BASIC) { + /* ===== BASIC TIOCSTI TEST ===== */ + child_pid = fork(); + ASSERT_GE(child_pid, 0); + + /* Perform the actual test in the child process */ + if (child_pid == 0) + run_basic_tiocsti_test(_metadata, self, variant); + + } else { + /* ===== FD PASSING SECURITY TEST ===== */ + int sockpair[2]; + + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sockpair), 0); + + child_pid = fork(); + ASSERT_GE(child_pid, 0); + + if (child_pid == 0) { + /* Child process - create PTY and send FD */ + close(sockpair[0]); + run_fdpass_tiocsti_test(_metadata, variant, + sockpair[1]); + } + + /* Parent process - receive FD and test TIOCSTI */ + close(sockpair[1]); + + int received_fd = recv_fd_via_socket(sockpair[0]); + + ASSERT_GE(received_fd, 0); + + bool parent_has_cap = self->initial_cap_sys_admin; + + TH_LOG("=== TIOCSTI FD Passing Test Context ==="); + TH_LOG("legacy_tiocsti: %d, Parent CAP_SYS_ADMIN: %s, Child: %s", + variant->legacy_tiocsti, parent_has_cap ? "yes" : "no", + variant->requires_cap ? "kept" : "dropped"); + + /* SECURITY TEST: Try TIOCSTI with FD opened by child */ + int result = test_tiocsti_injection(_metadata, received_fd); + + /* Log security concern if demonstrated */ + if (result == 0 && !variant->requires_cap) { + TH_LOG("*** SECURITY CONCERN DEMONSTRATED ***"); + TH_LOG("Privileged parent can use TIOCSTI on FD from unprivileged child"); + TH_LOG("This shows current process credentials are used, not opener credentials"); + } + + EXPECT_EQ(result, variant->expected_success) + { + TH_LOG("FD passing: expected error %d, got %d", + variant->expected_success, result); + } + + /* Signal child completion */ + char sync_byte = 'D'; + ssize_t bytes_written = write(sockpair[0], &sync_byte, 1); + + ASSERT_EQ(bytes_written, 1); + + close(received_fd); + close(sockpair[0]); + } + + /* Common child process cleanup for both test types */ + ASSERT_EQ(waitpid(child_pid, &status, 0), child_pid); + + if (WIFSIGNALED(status)) { + TH_LOG("Child terminated by signal %d", WTERMSIG(status)); + ASSERT_FALSE(WIFSIGNALED(status)) + { + TH_LOG("Child process failed assertion"); + } + } else { + EXPECT_EQ(WEXITSTATUS(status), 0); + } +} + +TEST_HARNESS_MAIN --- base-commit: e6b9dce0aeeb91dfc0974ab87f02454e24566182 change-id: 20250618-toicsti-bug-7822b8e94a32 Best regards, -- Abhinav Saxena <xandfury(a)gmail.com>

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