July 2025 - Linux-kselftest-mirror

[PATCH] selftests/filesystems: Use return value of the function 'chdir()'

by Alessandro Zanni

Fix to use the return value of the function 'chdir("/")' and check if the return is either 0 (ok) or 1 (not ok, so the test stops). The patch fies the solves the following errors: mount-notify_test.c:468:17: warning: ignoring return value of ‘chdir’ declared with attribute ‘warn_unused_result’ [-Wunused-result] 468 | chdir("/"); mount-notify_test_ns.c:489:17: warning: ignoring return value of ‘chdir’ declared with attribute ‘warn_unused_result’ [-Wunused- result] 489 | chdir("/"); To reproduce the issue, use the command: make kselftest TARGET=filesystems/statmount Signed-off-by: Alessandro Zanni <alessandro.zanni87(a)gmail.com> --- .../selftests/filesystems/mount-notify/mount-notify_test.c | 2 +- .../selftests/filesystems/mount-notify/mount-notify_test_ns.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c index 5a3b0ace1a88..a7f899599d52 100644 --- a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c +++ b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c @@ -458,7 +458,7 @@ TEST_F(fanotify, rmdir) ASSERT_GE(ret, 0); if (ret == 0) { - chdir("/"); + ASSERT_EQ(0, chdir("/")); unshare(CLONE_NEWNS); mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL); umount2("/a", MNT_DETACH); diff --git a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c index d91946e69591..dc9eb3087a1a 100644 --- a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c +++ b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c @@ -486,7 +486,7 @@ TEST_F(fanotify, rmdir) ASSERT_GE(ret, 0); if (ret == 0) { - chdir("/"); + ASSERT_EQ(0, chdir("/")); unshare(CLONE_NEWNS); mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL); umount2("/a", MNT_DETACH); -- 2.43.0

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[PATCH v3] 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> --- 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 50d7027b2ae3..7f6fbe5a0cd5 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 000000000000..c6373aba6636 --- /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 000000000000..1eafef6e36fa --- /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; +} + +/* + * Drop to nobody user (uid/gid 65534) to lose all capabilities + */ +static inline bool drop_to_nobody(struct __test_metadata *_metadata) +{ + ASSERT_EQ(setgroups(0, NULL), 0); + ASSERT_EQ(setgid(65534), 0); + ASSERT_EQ(setuid(65534), 0); + + 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) { + if (value < 0 || value > 1) + value = -1; /* Invalid value */ + } else { + value = -1; /* Failed to parse */ + } + + fclose(fp); + 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) + success = true; + else + TH_LOG("Failed to write legacy_tiocsti: %s", strerror(errno)); + + fclose(fp); + 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; +} + +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)"); + + /* Test if we can modify the sysctl (requires appropriate privileges) */ + self->can_modify_sysctl = set_legacy_tiocsti_setting(_metadata, + self->original_legacy_tiocsti_setting); + if (!self->can_modify_sysctl) + TH_LOG("Warning: Cannot modify legacy_tiocsti sysctl - will skip mismatched variants"); +} + +FIXTURE_TEARDOWN(tiocsti) +{ + /* + * Backup restoration - + * each test should restore its own sysctl changes + */ + if (self->can_modify_sysctl && + self->original_legacy_tiocsti_setting >= 0) { + 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 saved_legacy_tiocsti = get_legacy_tiocsti_setting(_metadata); + bool need_restore = false; + int status; + pid_t child_pid; + + /* Set legacy_tiocsti sysctl to match variant requirement */ + if (self->can_modify_sysctl) { + if (saved_legacy_tiocsti != variant->legacy_tiocsti) { + if (!set_legacy_tiocsti_setting(_metadata, + variant->legacy_tiocsti)) { + SKIP(return, + "Failed to set legacy_tiocsti sysctl"); + } + need_restore = true; + } + } else { + /* + * Can't modify sysctl + * - check if current value matches variant + */ + if (self->original_legacy_tiocsti_setting != + variant->legacy_tiocsti) { + SKIP(return, + "legacy_tiocsti setting mismatch and cannot modify sysctl"); + } + } + + /* Common skip conditions */ + if (variant->test_type == TEST_PTY_TIOCSTI_BASIC && !self->has_pty) { + SKIP(goto restore_sysctl, + "PTY not available for controlling terminal test"); + } + + if (variant->test_type == TEST_PTY_TIOCSTI_FD_PASSING && + !self->initial_cap_sys_admin) { + SKIP(goto restore_sysctl, + "FD Pass tests require CAP_SYS_ADMIN"); + } + + if (variant->requires_cap && !self->initial_cap_sys_admin) { + SKIP(goto restore_sysctl, + "Test requires initial CAP_SYS_ADMIN"); + } + + if (variant->test_type == TEST_PTY_TIOCSTI_BASIC) { + /* ===== BASIC TIOCSTI TEST ===== */ + child_pid = fork(); + ASSERT_GE(child_pid, 0); + + if (child_pid == 0) { + /* Child process - perform the actual test */ + + /* Handle capability requirements */ + if (self->initial_cap_sys_admin && + !variant->requires_cap) + ASSERT_TRUE(drop_to_nobody(_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); + } + + } 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]); + signal(SIGHUP, SIG_IGN); + + /* Handle privilege dropping */ + if (!variant->requires_cap && has_cap_sys_admin()) + ASSERT_TRUE(drop_to_nobody(_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(sockpair[1], + child_slave_fd), + 0); + + /* Wait for parent completion signal */ + char sync_byte; + ssize_t bytes_read = read(sockpair[1], &sync_byte, 1); + + ASSERT_EQ(bytes_read, 1); + + close(child_master_fd); + close(child_slave_fd); + close(sockpair[1]); + _exit(0); + } + + /* 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); + } + +restore_sysctl: + if (need_restore) + set_legacy_tiocsti_setting(_metadata, saved_legacy_tiocsti); +} + +TEST_HARNESS_MAIN --- base-commit: 283564a43383d6f26a55546fe9ae345b5fa95e66 change-id: 20250618-toicsti-bug-7822b8e94a32 Best regards, -- Abhinav Saxena <xandfury(a)gmail.com>

1 month, 1 week

3
4
0 0

[PATCH v3 1/2] libbpf: add support for printing BTF character arrays as strings

by Blake Jones

The BTF dumper code currently displays arrays of characters as just that - arrays, with each character formatted individually. Sometimes this is what makes sense, but it's nice to be able to treat that array as a string. This change adds a special case to the btf_dump functionality to allow 0-terminated arrays of single-byte integer values to be printed as character strings. Characters for which isprint() returns false are printed as hex-escaped values. This is enabled when the new ".emit_strings" is set to 1 in the btf_dump_type_data_opts structure. As an example, here's what it looks like to dump the string "hello" using a few different field values for btf_dump_type_data_opts (.compact = 1): - .emit_strings = 0, .skip_names = 0: (char[6])['h','e','l','l','o',] - .emit_strings = 0, .skip_names = 1: ['h','e','l','l','o',] - .emit_strings = 1, .skip_names = 0: (char[6])"hello" - .emit_strings = 1, .skip_names = 1: "hello" Here's the string "h\xff", dumped with .compact = 1 and .skip_names = 1: - .emit_strings = 0: ['h',-1,] - .emit_strings = 1: "h\xff" Signed-off-by: Blake Jones <blakejones(a)google.com> --- tools/lib/bpf/btf.h | 3 ++- tools/lib/bpf/btf_dump.c | 55 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 56 insertions(+), 2 deletions(-) diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index 4392451d634b..ccfd905f03df 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -326,9 +326,10 @@ struct btf_dump_type_data_opts { bool compact; /* no newlines/indentation */ bool skip_names; /* skip member/type names */ bool emit_zeroes; /* show 0-valued fields */ + bool emit_strings; /* print char arrays as strings */ size_t :0; }; -#define btf_dump_type_data_opts__last_field emit_zeroes +#define btf_dump_type_data_opts__last_field emit_strings LIBBPF_API int btf_dump__dump_type_data(struct btf_dump *d, __u32 id, diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c index 460c3e57fadb..7c2f1f13f958 100644 --- a/tools/lib/bpf/btf_dump.c +++ b/tools/lib/bpf/btf_dump.c @@ -68,6 +68,7 @@ struct btf_dump_data { bool compact; bool skip_names; bool emit_zeroes; + bool emit_strings; __u8 indent_lvl; /* base indent level */ char indent_str[BTF_DATA_INDENT_STR_LEN]; /* below are used during iteration */ @@ -2028,6 +2029,52 @@ static int btf_dump_var_data(struct btf_dump *d, return btf_dump_dump_type_data(d, NULL, t, type_id, data, 0, 0); } +static int btf_dump_string_data(struct btf_dump *d, + const struct btf_type *t, + __u32 id, + const void *data) +{ + const struct btf_array *array = btf_array(t); + const char *chars = data; + __u32 i; + + /* Make sure it is a NUL-terminated string. */ + for (i = 0; i < array->nelems; i++) { + if ((void *)(chars + i) >= d->typed_dump->data_end) + return -E2BIG; + if (chars[i] == '\0') + break; + } + if (i == array->nelems) { + /* The caller will print this as a regular array. */ + return -EINVAL; + } + + btf_dump_data_pfx(d); + btf_dump_printf(d, "\""); + + for (i = 0; i < array->nelems; i++) { + char c = chars[i]; + + if (c == '\0') { + /* + * When printing character arrays as strings, NUL bytes + * are always treated as string terminators; they are + * never printed. + */ + break; + } + if (isprint(c)) + btf_dump_printf(d, "%c", c); + else + btf_dump_printf(d, "\\x%02x", (__u8)c); + } + + btf_dump_printf(d, "\""); + + return 0; +} + static int btf_dump_array_data(struct btf_dump *d, const struct btf_type *t, __u32 id, @@ -2055,8 +2102,13 @@ static int btf_dump_array_data(struct btf_dump *d, * char arrays, so if size is 1 and element is * printable as a char, we'll do that. */ - if (elem_size == 1) + if (elem_size == 1) { + if (d->typed_dump->emit_strings && + btf_dump_string_data(d, t, id, data) == 0) { + return 0; + } d->typed_dump->is_array_char = true; + } } /* note that we increment depth before calling btf_dump_print() below; @@ -2544,6 +2596,7 @@ int btf_dump__dump_type_data(struct btf_dump *d, __u32 id, d->typed_dump->compact = OPTS_GET(opts, compact, false); d->typed_dump->skip_names = OPTS_GET(opts, skip_names, false); d->typed_dump->emit_zeroes = OPTS_GET(opts, emit_zeroes, false); + d->typed_dump->emit_strings = OPTS_GET(opts, emit_strings, false); ret = btf_dump_dump_type_data(d, NULL, t, id, data, 0, 0); -- 2.49.0.1204.g71687c7c1d-goog

1 month, 1 week

7
12
0 0

[PATCH v4 00/23] ARM64 PMU Partitioning

by Colton Lewis

This series creates a new PMU scheme on ARM, a partitioned PMU that allows reserving a subset of counters for more direct guest access, significantly reducing overhead. More details, including performance benchmarks, can be read in the v1 cover letter linked below. v4: * Apply Mark Brown's non-UNDEF FGT control commit to the PMU FGT controls and calculate those controls with the others in kvm_calculate_traps() * Introduce lazy context swaps for guests that only turns on for guests that have enabled partitioning and accessed PMU registers. * Rename pmu-part.c to pmu-direct.c because future features might achieve direct PMU access without partitioning. * Better explain certain commits, such as why the untrapped registers are safe to untrap. * Reduce the PMU include cleanup down to only what is still necessary and explain why. v3: https://lore.kernel.org/kvm/20250626200459.1153955-1-coltonlewis@google.com/ v2: https://lore.kernel.org/kvm/20250620221326.1261128-1-coltonlewis@google.com/ v1: https://lore.kernel.org/kvm/20250602192702.2125115-1-coltonlewis@google.com/ Colton Lewis (21): arm64: cpufeature: Add cpucap for HPMN0 KVM: arm64: Reorganize PMU functions perf: arm_pmuv3: Introduce method to partition the PMU perf: arm_pmuv3: Generalize counter bitmasks perf: arm_pmuv3: Keep out of guest counter partition KVM: arm64: Account for partitioning in kvm_pmu_get_max_counters() KVM: arm64: Set up FGT for Partitioned PMU KVM: arm64: Writethrough trapped PMEVTYPER register KVM: arm64: Use physical PMSELR for PMXEVTYPER if partitioned KVM: arm64: Writethrough trapped PMOVS register KVM: arm64: Write fast path PMU register handlers KVM: arm64: Setup MDCR_EL2 to handle a partitioned PMU KVM: arm64: Account for partitioning in PMCR_EL0 access KVM: arm64: Context swap Partitioned PMU guest registers KVM: arm64: Enforce PMU event filter at vcpu_load() KVM: arm64: Extract enum debug_owner to enum vcpu_register_owner KVM: arm64: Implement lazy PMU context swaps perf: arm_pmuv3: Handle IRQs for Partitioned PMU guest counters KVM: arm64: Inject recorded guest interrupts KVM: arm64: Add ioctl to partition the PMU when supported KVM: arm64: selftests: Add test case for partitioned PMU Marc Zyngier (1): KVM: arm64: Reorganize PMU includes Mark Brown (1): KVM: arm64: Introduce non-UNDEF FGT control Documentation/virt/kvm/api.rst | 21 + arch/arm/include/asm/arm_pmuv3.h | 38 + arch/arm64/include/asm/arm_pmuv3.h | 61 +- arch/arm64/include/asm/kvm_host.h | 34 +- arch/arm64/include/asm/kvm_pmu.h | 123 +++ arch/arm64/include/asm/kvm_types.h | 7 +- arch/arm64/kernel/cpufeature.c | 8 + arch/arm64/kvm/Makefile | 2 +- arch/arm64/kvm/arm.c | 22 + arch/arm64/kvm/debug.c | 33 +- arch/arm64/kvm/hyp/include/hyp/debug-sr.h | 6 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 181 ++++- arch/arm64/kvm/pmu-direct.c | 395 ++++++++++ arch/arm64/kvm/pmu-emul.c | 674 +--------------- arch/arm64/kvm/pmu.c | 725 ++++++++++++++++++ arch/arm64/kvm/sys_regs.c | 137 +++- arch/arm64/tools/cpucaps | 1 + arch/arm64/tools/sysreg | 6 +- drivers/perf/arm_pmuv3.c | 128 +++- include/linux/perf/arm_pmu.h | 1 + include/linux/perf/arm_pmuv3.h | 14 +- include/uapi/linux/kvm.h | 4 + tools/include/uapi/linux/kvm.h | 2 + .../selftests/kvm/arm64/vpmu_counter_access.c | 62 +- 24 files changed, 1910 insertions(+), 775 deletions(-) create mode 100644 arch/arm64/kvm/pmu-direct.c base-commit: 79150772457f4d45e38b842d786240c36bb1f97f -- 2.50.0.727.gbf7dc18ff4-goog

1 month, 1 week

3
30
0 0

[PATCH] selftests/mm: use __auto_type in swap() macro

by Pranav Tyagi

Replace typeof() with __auto_type in the swap() macro in uffd-stress.c. __auto_type was introduced in GCC 4.9 and reduces the compile time for all compilers. No functional changes intended. Signed-off-by: Pranav Tyagi <pranav.tyagi03(a)gmail.com> --- tools/testing/selftests/mm/uffd-stress.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c index 40af7f67c407..c0f64df5085c 100644 --- a/tools/testing/selftests/mm/uffd-stress.c +++ b/tools/testing/selftests/mm/uffd-stress.c @@ -51,7 +51,7 @@ static char *zeropage; pthread_attr_t attr; #define swap(a, b) \ - do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0) + do { __auto_type __tmp = (a); (a) = (b); (b) = __tmp; } while (0) const char *examples = "# Run anonymous memory test on 100MiB region with 99999 bounces:\n" -- 2.49.0

1 month, 2 weeks

3
5
0 0

[PATCH] rust: kernel: remove support for unused host `#[test]`s

by Miguel Ojeda

Since commit 028df914e546 ("rust: str: convert `rusttest` tests into KUnit"), we do not have anymore host `#[test]`s that run in the host. Moreover, we do not plan to add any new ones -- tests should generally run within KUnit, since there they are built the same way the kernel does. While we may want to have some way to define tests that can also be run outside the kernel, we still want to test within the kernel too [1], and thus would likely use a custom syntax anyway to define them. Thus simplify the `rusttest` target by removing support for host `#[test]`s for the `kernel` crate. This still maintains the support for the `macros` crate, even though we do not have any such tests there. Link: https://lore.kernel.org/rust-for-linux/CABVgOS=AKHSfifp0S68K3jgNZAkALBr=7iF… [1] Signed-off-by: Miguel Ojeda <ojeda(a)kernel.org> --- rust/Makefile | 9 +-------- rust/kernel/alloc.rs | 6 +++--- rust/kernel/error.rs | 4 ++-- rust/kernel/lib.rs | 2 +- 4 files changed, 7 insertions(+), 14 deletions(-) diff --git a/rust/Makefile b/rust/Makefile index 115b63b7d1e3..5290b37868dd 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -235,7 +235,7 @@ quiet_cmd_rustc_test = $(RUSTC_OR_CLIPPY_QUIET) T $< $(objtree)/$(obj)/test/$(subst rusttest-,,$@) $(rust_test_quiet) \ $(rustc_test_run_flags) -rusttest: rusttest-macros rusttest-kernel +rusttest: rusttest-macros rusttest-macros: private rustc_target_flags = --extern proc_macro \ --extern macros --extern kernel --extern pin_init @@ -245,13 +245,6 @@ rusttest-macros: $(src)/macros/lib.rs \ +$(call if_changed,rustc_test) +$(call if_changed,rustdoc_test) -rusttest-kernel: private rustc_target_flags = --extern ffi --extern pin_init \ - --extern build_error --extern macros --extern bindings --extern uapi -rusttest-kernel: $(src)/kernel/lib.rs rusttestlib-ffi rusttestlib-kernel \ - rusttestlib-build_error rusttestlib-macros rusttestlib-bindings \ - rusttestlib-uapi rusttestlib-pin_init FORCE - +$(call if_changed,rustc_test) - ifdef CONFIG_CC_IS_CLANG bindgen_c_flags = $(c_flags) else diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs index a2c49e5494d3..335ae3271fa8 100644 --- a/rust/kernel/alloc.rs +++ b/rust/kernel/alloc.rs @@ -2,16 +2,16 @@ //! Implementation of the kernel's memory allocation infrastructure. -#[cfg(not(any(test, testlib)))] +#[cfg(not(testlib))] pub mod allocator; pub mod kbox; pub mod kvec; pub mod layout; -#[cfg(any(test, testlib))] +#[cfg(testlib)] pub mod allocator_test; -#[cfg(any(test, testlib))] +#[cfg(testlib)] pub use self::allocator_test as allocator; pub use self::kbox::Box; diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs index 3dee3139fcd4..7812aca1b6ef 100644 --- a/rust/kernel/error.rs +++ b/rust/kernel/error.rs @@ -157,7 +157,7 @@ pub fn to_ptr<T>(self) -> *mut T { } /// Returns a string representing the error, if one exists. - #[cfg(not(any(test, testlib)))] + #[cfg(not(testlib))] pub fn name(&self) -> Option<&'static CStr> { // SAFETY: Just an FFI call, there are no extra safety requirements. let ptr = unsafe { bindings::errname(-self.0.get()) }; @@ -174,7 +174,7 @@ pub fn name(&self) -> Option<&'static CStr> { /// When `testlib` is configured, this always returns `None` to avoid the dependency on a /// kernel function so that tests that use this (e.g., by calling [`Result::unwrap`]) can still /// run in userspace. - #[cfg(any(test, testlib))] + #[cfg(testlib)] pub fn name(&self) -> Option<&'static CStr> { None } diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index e13d6ed88fa6..8a0153f61732 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -197,7 +197,7 @@ pub const fn as_ptr(&self) -> *mut bindings::module { } } -#[cfg(not(any(testlib, test)))] +#[cfg(not(testlib))] #[panic_handler] fn panic(info: &core::panic::PanicInfo<'_>) -> ! { pr_emerg!("{}\n", info); base-commit: 89be9a83ccf1f88522317ce02f854f30d6115c41 -- 2.50.1

1 month, 2 weeks

4
4
0 0

[PATCH v2 0/8] selftests/mm: Add compiler flags and fix found warnings

by Muhammad Usama Anjum

Recently, I reviewed a patch on the mm/kselftest mailing list about a test which had obvious type mismatch fix in it. It was strange why that wasn't caught during development and when patch was accepted. This led me to discover that those extra compiler options to catch these warnings aren't being used. When I added them, I found tens of warnings in just mm suite. In this series, I'm adding these flags and fixing those warnings. In the last try several months ago [1], I'd patches for individual tests. I've made patches better by grouping the same type of fixes together. Hence there is no changelog for individual patches. The changes have been build tested on x86_64, arm64, powerpc64 and partially on riscv64. The test run with and without this series has been done on x86_64. --- Changes since v1: - Drop test harness patch which isn't needed anymore - Revamp how patches are written per same kind of failure Muhammad Usama Anjum (8): selftests/mm: Add -Wunreachable-code and fix warnings selftests/mm: protection_keys: Fix dead code selftests: kselftest.h: Add __unused macro selftests/mm: Add -Wunused family of flags selftests/mm: Remove unused parameters selftests/mm: Mark unused arguments with __unused selftests/mm: Mark unused arguments with __unused selftests/mm: Fix unused parameter warnings for different architectures tools/testing/selftests/kselftest.h | 4 ++ tools/testing/selftests/mm/Makefile | 3 +- tools/testing/selftests/mm/compaction_test.c | 2 +- tools/testing/selftests/mm/cow.c | 22 +++++------ tools/testing/selftests/mm/droppable.c | 2 +- tools/testing/selftests/mm/gup_longterm.c | 2 +- tools/testing/selftests/mm/hmm-tests.c | 5 +-- tools/testing/selftests/mm/hugepage-vmemmap.c | 2 +- tools/testing/selftests/mm/hugetlb-madvise.c | 2 +- .../selftests/mm/hugetlb-soft-offline.c | 2 +- .../selftests/mm/hugetlb_fault_after_madv.c | 4 +- .../selftests/mm/hugetlb_madv_vs_map.c | 6 +-- tools/testing/selftests/mm/ksm_tests.c | 17 ++++----- tools/testing/selftests/mm/madv_populate.c | 2 +- tools/testing/selftests/mm/map_populate.c | 2 +- tools/testing/selftests/mm/memfd_secret.c | 6 +-- .../testing/selftests/mm/mlock-random-test.c | 2 +- tools/testing/selftests/mm/mlock2-tests.c | 2 +- tools/testing/selftests/mm/mseal_test.c | 8 +++- tools/testing/selftests/mm/on-fault-limit.c | 2 +- tools/testing/selftests/mm/pfnmap.c | 2 +- tools/testing/selftests/mm/pkey-arm64.h | 5 ++- tools/testing/selftests/mm/pkey-powerpc.h | 2 +- tools/testing/selftests/mm/pkey-x86.h | 3 +- .../selftests/mm/pkey_sighandler_tests.c | 35 ++++++++++++----- tools/testing/selftests/mm/protection_keys.c | 22 +++++------ tools/testing/selftests/mm/soft-dirty.c | 6 +-- .../selftests/mm/split_huge_page_test.c | 8 ++-- tools/testing/selftests/mm/uffd-common.c | 15 ++++---- tools/testing/selftests/mm/uffd-common.h | 2 +- tools/testing/selftests/mm/uffd-stress.c | 2 +- tools/testing/selftests/mm/uffd-unit-tests.c | 38 +++++++++---------- tools/testing/selftests/mm/uffd-wp-mremap.c | 2 +- .../selftests/mm/virtual_address_range.c | 2 +- 34 files changed, 130 insertions(+), 111 deletions(-) -- 2.39.5

1 month, 2 weeks

5
21
0 0

[PATCH 00/33] vfio: Introduce selftests for VFIO

by David Matlack

This series introduces VFIO selftests, located in tools/testing/selftests/vfio/. VFIO selftests aim to enable kernel developers to write and run tests that take the form of userspace programs that interact with VFIO and IOMMUFD uAPIs. VFIO selftests can be used to write functional tests for new features, regression tests for bugs, and performance tests for optimizations. These tests are designed to interact with real PCI devices, i.e. they do not rely on mocking out or faking any behavior in the kernel. This allows the tests to exercise not only VFIO but also IOMMUFD, the IOMMU driver, interrupt remapping, IRQ handling, etc. For more background on the motivation and design of this series, please see the RFC: https://lore.kernel.org/kvm/20250523233018.1702151-1-dmatlack@google.com/ This series can also be found on GitHub: https://github.com/dmatlack/linux/tree/vfio/selftests/v1 Changelog ----------------------------------------------------------------------- RFC: https://lore.kernel.org/kvm/20250523233018.1702151-1-dmatlack@google.com/ - Add symlink to linux/pci_ids.h instead of copying (Jason) - Add symlinks to drivers/dma/*/*.h instead of copying (Jason) - Automatically replicate vfio_dma_mapping_test across backing sources using fixture variants (Jason) - Automatically replicate vfio_dma_mapping_test and vfio_pci_driver_test across all iommu_modes using fixture variants (Jason) - Invert access() check in vfio_dma_mapping_test (me) - Use driver_override instead of add/remove_id (Alex) - Allow tests to get BDF from env var (Alex) - Use KSFT_FAIL instead of 1 to exit with failure (Alex) - Unconditionally create $(LIBVFIO_O_DIRS) to avoid target conflict with ../cgroup/lib/libcgroup.mk when building KVM selftests (me) - Allow VFIO selftests to run automatically by switching from TEST_GEN_PROGS_EXTENDED to TEST_GEN_PROGS. Automatically run selftests will use $VFIO_SELFTESTS_BDF environment variable to know which device to use (Alex) - Replace hardcoded SZ_4K with getpagesize() in vfio_dma_mapping_test to support platforms with other page sizes (me) - Make all global variables static where possible (me) - Pass argc and argv to test_harness_main() so that users can pass flags to the kselftest harness (me) Instructions ----------------------------------------------------------------------- Running VFIO selftests requires at a PCI device bound to vfio-pci for the tests to use. The address of this device is passed to the test as a segment:bus:device.function string, which must match the path to the device in /sys/bus/pci/devices/ (e.g. 0000:00:04.0). Once you have chosen a device, there is a helper script provided to unbind the device from its current driver, bind it to vfio-pci, export the environment variable $VFIO_SELFTESTS_BDF, and launch a shell: $ tools/testing/selftests/vfio/run.sh -d 0000:00:04.0 -s The -d option tells the script which device to use and the -s option tells the script to launch a shell. Additionally, the VFIO selftest vfio_dma_mapping_test has test cases that rely on HugeTLB pages being available, otherwise they are skipped. To enable those tests make sure at least 1 2MB and 1 1GB HugeTLB pages are available. $ echo 1 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages $ echo 1 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages To run all VFIO selftests using make: $ make -C tools/testing/selftests/vfio run_tests To run individual tests: $ tools/testing/selftests/vfio/vfio_dma_mapping_test $ tools/testing/selftests/vfio/vfio_dma_mapping_test -v iommufd_anonymous_hugetlb_2mb $ tools/testing/selftests/vfio/vfio_dma_mapping_test -r vfio_dma_mapping_test.iommufd_anonymous_hugetlb_2mb.dma_map_unmap The environment variable $VFIO_SELFTESTS_BDF can be overridden for a specific test by passing in the BDF on the command line as the last positional argument. $ tools/testing/selftests/vfio/vfio_dma_mapping_test 0000:00:04.0 $ tools/testing/selftests/vfio/vfio_dma_mapping_test -v iommufd_anonymous_hugetlb_2mb 0000:00:04.0 $ tools/testing/selftests/vfio/vfio_dma_mapping_test -r vfio_dma_mapping_test.iommufd_anonymous_hugetlb_2mb.dma_map_unmap 0000:00:04.0 When you are done, free the HugeTLB pages and exit the shell started by run.sh. Exiting the shell will cause the device to be unbound from vfio-pci and bound back to its original driver. $ echo 0 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages $ echo 0 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages $ exit It's also possible to use run.sh to run just a single test hermetically, rather than dropping into a shell: $ tools/testing/selftests/vfio/run.sh -d 0000:00:04.0 -- tools/testing/selftests/vfio/vfio_dma_mapping_test -v iommufd_anonymous Tests ----------------------------------------------------------------------- There are 5 tests in this series, mostly to demonstrate as a proof-of-concept: - tools/testing/selftests/vfio/vfio_pci_device_test.c - tools/testing/selftests/vfio/vfio_pci_driver_test.c - tools/testing/selftests/vfio/vfio_iommufd_setup_test.c - tools/testing/selftests/vfio/vfio_dma_mapping_test.c - tools/testing/selftests/kvm/vfio_pci_device_irq_test.c Future Areas of Development ----------------------------------------------------------------------- Library: - Driver support for devices that can be used on AMD, ARM, and other platforms (e.g. mlx5). - Driver support for a device available in QEMU VMs (e.g. pcie-ats-testdev [1]) - Support for tests that use multiple devices. - Support for IOMMU groups with multiple devices. - Support for multiple devices sharing the same container/iommufd. - Sharing TEST_ASSERT() macros and other common code between KVM and VFIO selftests. Tests: - DMA mapping performance tests for BARs/HugeTLB/etc. - Porting tests from https://github.com/awilliam/tests/commits/for-clg/ to selftests. - Live Update selftests. - Porting Sean's KVM selftest for posted interrupts to use the VFIO selftests library [2] Cc: Alex Williamson <alex.williamson(a)redhat.com> Cc: Jason Gunthorpe <jgg(a)nvidia.com> Cc: Kevin Tian <kevin.tian(a)intel.com> Cc: Paolo Bonzini <pbonzini(a)redhat.com> Cc: Sean Christopherson <seanjc(a)google.com> Cc: Vipin Sharma <vipinsh(a)google.com> Cc: Josh Hilke <jrhilke(a)google.com> Cc: Aaron Lewis <aaronlewis(a)google.com> Cc: Pasha Tatashin <pasha.tatashin(a)soleen.com> Cc: Saeed Mahameed <saeedm(a)nvidia.com> Cc: Adithya Jayachandran <ajayachandra(a)nvidia.com> Cc: Joel Granados <joel.granados(a)kernel.org> [1] https://github.com/Joelgranados/qemu/blob/pcie-testdev/hw/misc/pcie-ats-tes… [2] https://lore.kernel.org/kvm/20250404193923.1413163-68-seanjc@google.com/ David Matlack (28): selftests: Create tools/testing/selftests/vfio vfio: selftests: Add a helper library for VFIO selftests vfio: selftests: Introduce vfio_pci_device_test tools headers: Add stub definition for __iomem tools headers: Import asm-generic MMIO helpers tools headers: Import x86 MMIO helper overrides tools headers: Import iosubmit_cmds512() tools headers: Add symlink to linux/pci_ids.h vfio: selftests: Keep track of DMA regions mapped into the device vfio: selftests: Enable asserting MSI eventfds not firing vfio: selftests: Add a helper for matching vendor+device IDs vfio: selftests: Add driver framework vfio: sefltests: Add vfio_pci_driver_test dmaengine: ioat: Move system_has_dca_enabled() to dma.h vfio: selftests: Add driver for Intel CBDMA dmaengine: idxd: Allow registers.h to be included from tools/ vfio: selftests: Add driver for Intel DSA vfio: selftests: Move helper to get cdev path to libvfio vfio: selftests: Encapsulate IOMMU mode vfio: selftests: Replicate tests across all iommu_modes vfio: selftests: Add vfio_type1v2_mode vfio: selftests: Add iommufd_compat_type1{,v2} modes vfio: selftests: Add iommufd mode vfio: selftests: Make iommufd the default iommu_mode vfio: selftests: Add a script to help with running VFIO selftests KVM: selftests: Build and link sefltests/vfio/lib into KVM selftests KVM: selftests: Test sending a vfio-pci device IRQ to a VM KVM: selftests: Add -d option to vfio_pci_device_irq_test for device-sent MSIs Josh Hilke (5): vfio: selftests: Test basic VFIO and IOMMUFD integration vfio: selftests: Move vfio dma mapping test to their own file vfio: selftests: Add test to reset vfio device. vfio: selftests: Add DMA mapping tests for 2M and 1G HugeTLB vfio: selftests: Validate 2M/1G HugeTLB are mapped as 2M/1G in IOMMU MAINTAINERS | 7 + drivers/dma/idxd/registers.h | 4 + drivers/dma/ioat/dma.h | 2 + drivers/dma/ioat/hw.h | 3 - tools/arch/x86/include/asm/io.h | 101 +++ tools/arch/x86/include/asm/special_insns.h | 27 + tools/include/asm-generic/io.h | 482 ++++++++++++++ tools/include/asm/io.h | 11 + tools/include/linux/compiler.h | 4 + tools/include/linux/io.h | 4 +- tools/include/linux/pci_ids.h | 1 + tools/testing/selftests/Makefile | 1 + tools/testing/selftests/kvm/Makefile.kvm | 4 + .../testing/selftests/kvm/include/kvm_util.h | 4 + tools/testing/selftests/kvm/lib/kvm_util.c | 21 + .../selftests/kvm/vfio_pci_device_irq_test.c | 172 +++++ tools/testing/selftests/vfio/.gitignore | 7 + tools/testing/selftests/vfio/Makefile | 21 + .../selftests/vfio/lib/drivers/dsa/dsa.c | 416 ++++++++++++ .../vfio/lib/drivers/dsa/registers.h | 1 + .../selftests/vfio/lib/drivers/ioat/hw.h | 1 + .../selftests/vfio/lib/drivers/ioat/ioat.c | 235 +++++++ .../vfio/lib/drivers/ioat/registers.h | 1 + .../selftests/vfio/lib/include/vfio_util.h | 295 +++++++++ tools/testing/selftests/vfio/lib/libvfio.mk | 24 + .../selftests/vfio/lib/vfio_pci_device.c | 594 ++++++++++++++++++ .../selftests/vfio/lib/vfio_pci_driver.c | 126 ++++ tools/testing/selftests/vfio/run.sh | 109 ++++ .../selftests/vfio/vfio_dma_mapping_test.c | 199 ++++++ .../selftests/vfio/vfio_iommufd_setup_test.c | 127 ++++ .../selftests/vfio/vfio_pci_device_test.c | 176 ++++++ .../selftests/vfio/vfio_pci_driver_test.c | 247 ++++++++ 32 files changed, 3423 insertions(+), 4 deletions(-) create mode 100644 tools/arch/x86/include/asm/io.h create mode 100644 tools/arch/x86/include/asm/special_insns.h create mode 100644 tools/include/asm-generic/io.h create mode 100644 tools/include/asm/io.h create mode 120000 tools/include/linux/pci_ids.h create mode 100644 tools/testing/selftests/kvm/vfio_pci_device_irq_test.c create mode 100644 tools/testing/selftests/vfio/.gitignore create mode 100644 tools/testing/selftests/vfio/Makefile create mode 100644 tools/testing/selftests/vfio/lib/drivers/dsa/dsa.c create mode 120000 tools/testing/selftests/vfio/lib/drivers/dsa/registers.h create mode 120000 tools/testing/selftests/vfio/lib/drivers/ioat/hw.h create mode 100644 tools/testing/selftests/vfio/lib/drivers/ioat/ioat.c create mode 120000 tools/testing/selftests/vfio/lib/drivers/ioat/registers.h create mode 100644 tools/testing/selftests/vfio/lib/include/vfio_util.h create mode 100644 tools/testing/selftests/vfio/lib/libvfio.mk create mode 100644 tools/testing/selftests/vfio/lib/vfio_pci_device.c create mode 100644 tools/testing/selftests/vfio/lib/vfio_pci_driver.c create mode 100755 tools/testing/selftests/vfio/run.sh create mode 100644 tools/testing/selftests/vfio/vfio_dma_mapping_test.c create mode 100644 tools/testing/selftests/vfio/vfio_iommufd_setup_test.c create mode 100644 tools/testing/selftests/vfio/vfio_pci_device_test.c create mode 100644 tools/testing/selftests/vfio/vfio_pci_driver_test.c base-commit: e271ed52b344ac02d4581286961d0c40acc54c03 prerequisite-patch-id: c1decca4653262d3d2451e6fd4422ebff9c0b589 -- 2.50.0.rc2.701.gf1e915cc24-goog

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[PATCH v12] exec: Fix dead-lock in de_thread with ptrace_attach

by Bernd Edlinger

This introduces signal->exec_bprm, which is used to fix the case when at least one of the sibling threads is traced, and therefore the trace process may dead-lock in ptrace_attach, but de_thread will need to wait for the tracer to continue execution. The solution is to detect this situation and allow ptrace_attach to continue by temporarily releasing the cred_guard_mutex, while de_thread() is still waiting for traced zombies to be eventually released by the tracer. In the case of the thread group leader we only have to wait for the thread to become a zombie, which may also need co-operation from the tracer due to PTRACE_O_TRACEEXIT. When a tracer wants to ptrace_attach a task that already is in execve, we simply retry the ptrace_may_access check while temporarily installing the new credentials and dumpability which are about to be used after execve completes. If the ptrace_attach happens on a thread that is a sibling-thread of the thread doing execve, it is sufficient to check against the old credentials, as this thread will be waited for, before the new credentials are installed. Other threads die quickly since the cred_guard_mutex is released, but a deadly signal is already pending. In case the mutex_lock_killable misses the signal, the non-zero current->signal->exec_bprm makes sure they release the mutex immediately and return with -ERESTARTNOINTR. This means there is no API change, unlike the previous version of this patch which was discussed here: https://lore.kernel.org/lkml/b6537ae6-31b1-5c50-f32b-8b8332ace882@hotmail.d… See tools/testing/selftests/ptrace/vmaccess.c for a test case that gets fixed by this change. Note that since the test case was originally designed to test the ptrace_attach returning an error in this situation, the test expectation needed to be adjusted, to allow the API to succeed at the first attempt. Signed-off-by: Bernd Edlinger <bernd.edlinger(a)hotmail.de> --- fs/exec.c | 69 ++++++++++++++++------- fs/proc/base.c | 6 ++ include/linux/cred.h | 1 + include/linux/sched/signal.h | 18 ++++++ kernel/cred.c | 28 +++++++-- kernel/ptrace.c | 32 +++++++++++ kernel/seccomp.c | 12 +++- tools/testing/selftests/ptrace/vmaccess.c | 23 +++++--- 8 files changed, 155 insertions(+), 34 deletions(-) v10: Changes to previous version, make the PTRACE_ATTACH retun -EAGAIN, instead of execve return -ERESTARTSYS. Added some lessions learned to the description. v11: Check old and new credentials in PTRACE_ATTACH again without changing the API. Note: I got actually one response from an automatic checker to the v11 patch, https://lore.kernel.org/lkml/202107121344.wu68hEPF-lkp@intel.com/ which is complaining about: >> kernel/ptrace.c:425:26: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct cred const *old_cred @@ got struct cred const [noderef] __rcu *real_cred @@ 417 struct linux_binprm *bprm = task->signal->exec_bprm; 418 const struct cred *old_cred; 419 struct mm_struct *old_mm; 420 421 retval = down_write_killable(&task->signal->exec_update_lock); 422 if (retval) 423 goto unlock_creds; 424 task_lock(task); > 425 old_cred = task->real_cred; v12: Essentially identical to v11. - Fixed a minor merge conflict in linux v5.17, and fixed the above mentioned nit by adding __rcu to the declaration. - re-tested the patch with all linux versions from v5.11 to v6.6 v10 was an alternative approach which did imply an API change. But I would prefer to avoid such an API change. The difficult part is getting the right dumpability flags assigned before de_thread starts, hope you like this version. If not, the v10 is of course also acceptable. Thanks Bernd. diff --git a/fs/exec.c b/fs/exec.c index 2f2b0acec4f0..902d3b230485 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1041,11 +1041,13 @@ static int exec_mmap(struct mm_struct *mm) return 0; } -static int de_thread(struct task_struct *tsk) +static int de_thread(struct task_struct *tsk, struct linux_binprm *bprm) { struct signal_struct *sig = tsk->signal; struct sighand_struct *oldsighand = tsk->sighand; spinlock_t *lock = &oldsighand->siglock; + struct task_struct *t = tsk; + bool unsafe_execve_in_progress = false; if (thread_group_empty(tsk)) goto no_thread_group; @@ -1068,6 +1070,19 @@ static int de_thread(struct task_struct *tsk) if (!thread_group_leader(tsk)) sig->notify_count--; + while_each_thread(tsk, t) { + if (unlikely(t->ptrace) + && (t != tsk->group_leader || !t->exit_state)) + unsafe_execve_in_progress = true; + } + + if (unlikely(unsafe_execve_in_progress)) { + spin_unlock_irq(lock); + sig->exec_bprm = bprm; + mutex_unlock(&sig->cred_guard_mutex); + spin_lock_irq(lock); + } + while (sig->notify_count) { __set_current_state(TASK_KILLABLE); spin_unlock_irq(lock); @@ -1158,6 +1173,11 @@ static int de_thread(struct task_struct *tsk) release_task(leader); } + if (unlikely(unsafe_execve_in_progress)) { + mutex_lock(&sig->cred_guard_mutex); + sig->exec_bprm = NULL; + } + sig->group_exec_task = NULL; sig->notify_count = 0; @@ -1169,6 +1189,11 @@ static int de_thread(struct task_struct *tsk) return 0; killed: + if (unlikely(unsafe_execve_in_progress)) { + mutex_lock(&sig->cred_guard_mutex); + sig->exec_bprm = NULL; + } + /* protects against exit_notify() and __exit_signal() */ read_lock(&tasklist_lock); sig->group_exec_task = NULL; @@ -1253,6 +1278,24 @@ int begin_new_exec(struct linux_binprm * bprm) if (retval) return retval; + /* If the binary is not readable then enforce mm->dumpable=0 */ + would_dump(bprm, bprm->file); + if (bprm->have_execfd) + would_dump(bprm, bprm->executable); + + /* + * Figure out dumpability. Note that this checking only of current + * is wrong, but userspace depends on it. This should be testing + * bprm->secureexec instead. + */ + if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP || + is_dumpability_changed(current_cred(), bprm->cred) || + !(uid_eq(current_euid(), current_uid()) && + gid_eq(current_egid(), current_gid()))) + set_dumpable(bprm->mm, suid_dumpable); + else + set_dumpable(bprm->mm, SUID_DUMP_USER); + /* * Ensure all future errors are fatal. */ @@ -1261,7 +1304,7 @@ int begin_new_exec(struct linux_binprm * bprm) /* * Make this the only thread in the thread group. */ - retval = de_thread(me); + retval = de_thread(me, bprm); if (retval) goto out; @@ -1284,11 +1327,6 @@ int begin_new_exec(struct linux_binprm * bprm) if (retval) goto out; - /* If the binary is not readable then enforce mm->dumpable=0 */ - would_dump(bprm, bprm->file); - if (bprm->have_execfd) - would_dump(bprm, bprm->executable); - /* * Release all of the old mmap stuff */ @@ -1350,18 +1388,6 @@ int begin_new_exec(struct linux_binprm * bprm) me->sas_ss_sp = me->sas_ss_size = 0; - /* - * Figure out dumpability. Note that this checking only of current - * is wrong, but userspace depends on it. This should be testing - * bprm->secureexec instead. - */ - if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP || - !(uid_eq(current_euid(), current_uid()) && - gid_eq(current_egid(), current_gid()))) - set_dumpable(current->mm, suid_dumpable); - else - set_dumpable(current->mm, SUID_DUMP_USER); - perf_event_exec(); __set_task_comm(me, kbasename(bprm->filename), true); @@ -1480,6 +1506,11 @@ static int prepare_bprm_creds(struct linux_binprm *bprm) if (mutex_lock_interruptible(&current->signal->cred_guard_mutex)) return -ERESTARTNOINTR; + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + return -ERESTARTNOINTR; + } + bprm->cred = prepare_exec_creds(); if (likely(bprm->cred)) return 0; diff --git a/fs/proc/base.c b/fs/proc/base.c index ffd54617c354..0da9adfadb48 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2788,6 +2788,12 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf, if (rv < 0) goto out_free; + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + rv = -ERESTARTNOINTR; + goto out_free; + } + rv = security_setprocattr(PROC_I(inode)->op.lsm, file->f_path.dentry->d_name.name, page, count); diff --git a/include/linux/cred.h b/include/linux/cred.h index f923528d5cc4..b01e309f5686 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -159,6 +159,7 @@ extern const struct cred *get_task_cred(struct task_struct *); extern struct cred *cred_alloc_blank(void); extern struct cred *prepare_creds(void); extern struct cred *prepare_exec_creds(void); +extern bool is_dumpability_changed(const struct cred *, const struct cred *); extern int commit_creds(struct cred *); extern void abort_creds(struct cred *); extern const struct cred *override_creds(const struct cred *); diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 0014d3adaf84..14df7073a0a8 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -234,9 +234,27 @@ struct signal_struct { struct mm_struct *oom_mm; /* recorded mm when the thread group got * killed by the oom killer */ + struct linux_binprm *exec_bprm; /* Used to check ptrace_may_access + * against new credentials while + * de_thread is waiting for other + * traced threads to terminate. + * Set while de_thread is executing. + * The cred_guard_mutex is released + * after de_thread() has called + * zap_other_threads(), therefore + * a fatal signal is guaranteed to be + * already pending in the unlikely + * event, that + * current->signal->exec_bprm happens + * to be non-zero after the + * cred_guard_mutex was acquired. + */ + struct mutex cred_guard_mutex; /* guard against foreign influences on * credential calculations * (notably. ptrace) + * Held while execve runs, except when + * a sibling thread is being traced. * Deprecated do not use in new code. * Use exec_update_lock instead. */ diff --git a/kernel/cred.c b/kernel/cred.c index 98cb4eca23fb..586cb6c7cf6b 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -433,6 +433,28 @@ static bool cred_cap_issubset(const struct cred *set, const struct cred *subset) return false; } +/** + * is_dumpability_changed - Will changing creds from old to new + * affect the dumpability in commit_creds? + * + * Return: false - dumpability will not be changed in commit_creds. + * Return: true - dumpability will be changed to non-dumpable. + * + * @old: The old credentials + * @new: The new credentials + */ +bool is_dumpability_changed(const struct cred *old, const struct cred *new) +{ + if (!uid_eq(old->euid, new->euid) || + !gid_eq(old->egid, new->egid) || + !uid_eq(old->fsuid, new->fsuid) || + !gid_eq(old->fsgid, new->fsgid) || + !cred_cap_issubset(old, new)) + return true; + + return false; +} + /** * commit_creds - Install new credentials upon the current task * @new: The credentials to be assigned @@ -467,11 +489,7 @@ int commit_creds(struct cred *new) get_cred(new); /* we will require a ref for the subj creds too */ /* dumpability changes */ - if (!uid_eq(old->euid, new->euid) || - !gid_eq(old->egid, new->egid) || - !uid_eq(old->fsuid, new->fsuid) || - !gid_eq(old->fsgid, new->fsgid) || - !cred_cap_issubset(old, new)) { + if (is_dumpability_changed(old, new)) { if (task->mm) set_dumpable(task->mm, suid_dumpable); task->pdeath_signal = 0; diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 443057bee87c..eb1c450bb7d7 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -20,6 +20,7 @@ #include <linux/pagemap.h> #include <linux/ptrace.h> #include <linux/security.h> +#include <linux/binfmts.h> #include <linux/signal.h> #include <linux/uio.h> #include <linux/audit.h> @@ -435,6 +436,28 @@ static int ptrace_attach(struct task_struct *task, long request, if (retval) goto unlock_creds; + if (unlikely(task->in_execve)) { + struct linux_binprm *bprm = task->signal->exec_bprm; + const struct cred __rcu *old_cred; + struct mm_struct *old_mm; + + retval = down_write_killable(&task->signal->exec_update_lock); + if (retval) + goto unlock_creds; + task_lock(task); + old_cred = task->real_cred; + old_mm = task->mm; + rcu_assign_pointer(task->real_cred, bprm->cred); + task->mm = bprm->mm; + retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS); + rcu_assign_pointer(task->real_cred, old_cred); + task->mm = old_mm; + task_unlock(task); + up_write(&task->signal->exec_update_lock); + if (retval) + goto unlock_creds; + } + write_lock_irq(&tasklist_lock); retval = -EPERM; if (unlikely(task->exit_state)) @@ -508,6 +531,14 @@ static int ptrace_traceme(void) { int ret = -EPERM; + if (mutex_lock_interruptible(&current->signal->cred_guard_mutex)) + return -ERESTARTNOINTR; + + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + return -ERESTARTNOINTR; + } + write_lock_irq(&tasklist_lock); /* Are we already being traced? */ if (!current->ptrace) { @@ -523,6 +554,7 @@ static int ptrace_traceme(void) } } write_unlock_irq(&tasklist_lock); + mutex_unlock(&current->signal->cred_guard_mutex); return ret; } diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 255999ba9190..b29bbfa0b044 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -1955,9 +1955,15 @@ static long seccomp_set_mode_filter(unsigned int flags, * Make sure we cannot change seccomp or nnp state via TSYNC * while another thread is in the middle of calling exec. */ - if (flags & SECCOMP_FILTER_FLAG_TSYNC && - mutex_lock_killable(&current->signal->cred_guard_mutex)) - goto out_put_fd; + if (flags & SECCOMP_FILTER_FLAG_TSYNC) { + if (mutex_lock_killable(&current->signal->cred_guard_mutex)) + goto out_put_fd; + + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + goto out_put_fd; + } + } spin_lock_irq(&current->sighand->siglock); diff --git a/tools/testing/selftests/ptrace/vmaccess.c b/tools/testing/selftests/ptrace/vmaccess.c index 4db327b44586..3b7d81fb99bb 100644 --- a/tools/testing/selftests/ptrace/vmaccess.c +++ b/tools/testing/selftests/ptrace/vmaccess.c @@ -39,8 +39,15 @@ TEST(vmaccess) f = open(mm, O_RDONLY); ASSERT_GE(f, 0); close(f); - f = kill(pid, SIGCONT); - ASSERT_EQ(f, 0); + f = waitpid(-1, NULL, 0); + ASSERT_NE(f, -1); + ASSERT_NE(f, 0); + ASSERT_NE(f, pid); + f = waitpid(-1, NULL, 0); + ASSERT_EQ(f, pid); + f = waitpid(-1, NULL, 0); + ASSERT_EQ(f, -1); + ASSERT_EQ(errno, ECHILD); } TEST(attach) @@ -57,22 +64,24 @@ TEST(attach) sleep(1); k = ptrace(PTRACE_ATTACH, pid, 0L, 0L); - ASSERT_EQ(errno, EAGAIN); - ASSERT_EQ(k, -1); + ASSERT_EQ(k, 0); k = waitpid(-1, &s, WNOHANG); ASSERT_NE(k, -1); ASSERT_NE(k, 0); ASSERT_NE(k, pid); ASSERT_EQ(WIFEXITED(s), 1); ASSERT_EQ(WEXITSTATUS(s), 0); - sleep(1); - k = ptrace(PTRACE_ATTACH, pid, 0L, 0L); + k = waitpid(-1, &s, 0); + ASSERT_EQ(k, pid); + ASSERT_EQ(WIFSTOPPED(s), 1); + ASSERT_EQ(WSTOPSIG(s), SIGTRAP); + k = ptrace(PTRACE_CONT, pid, 0L, 0L); ASSERT_EQ(k, 0); k = waitpid(-1, &s, 0); ASSERT_EQ(k, pid); ASSERT_EQ(WIFSTOPPED(s), 1); ASSERT_EQ(WSTOPSIG(s), SIGSTOP); - k = ptrace(PTRACE_DETACH, pid, 0L, 0L); + k = ptrace(PTRACE_CONT, pid, 0L, 0L); ASSERT_EQ(k, 0); k = waitpid(-1, &s, 0); ASSERT_EQ(k, pid); -- 2.39.2

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[PATCH] selftests: harness: Rework is_signed_type() to avoid collision with overflow.h

by Sean Christopherson

Rename is_signed_type() to is_signed_var() to avoid colliding with a macro of the same name defined by linux/overflow.h. Note, overflow.h's version takes a type as the input, whereas the harness's version takes a variable! This fixes warnings (and presumably potential test failures) in tests that utilize the selftests harness and happen to (indirectly) include overflow.h. In file included from tools/include/linux/bits.h:34, from tools/include/linux/bitops.h:14, from tools/include/linux/hashtable.h:13, from include/kvm_util.h:11, from x86/userspace_msr_exit_test.c:11: tools/include/linux/overflow.h:31:9: error: "is_signed_type" redefined [-Werror] 31 | #define is_signed_type(type) (((type)(-1)) < (type)1) | ^~~~~~~~~~~~~~ In file included from include/kvm_test_harness.h:11, from x86/userspace_msr_exit_test.c:9: ../kselftest_harness.h:754:9: note: this is the location of the previous definition 754 | #define is_signed_type(var) (!!(((__typeof__(var))(-1)) < (__typeof__(var))1)) | ^~~~~~~~~~~~~~ Opportunistically use is_signed_type() to implement is_signed_var() so that the relationship and differences are obvious. Fixes: fc92099902fb ("tools headers: Synchronize linux/bits.h with the kernel sources") Cc: Vincent Mailhol <mailhol.vincent(a)wanadoo.fr> Cc: Arnaldo Carvalho de Melo <acme(a)redhat.com> Signed-off-by: Sean Christopherson <seanjc(a)google.com> --- This is probably compile-tested only, I don't think any of the KVM selftests utilize the harness's EXPECT macros. tools/testing/selftests/kselftest_harness.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h index 2925e47db995..f3e7a46345db 100644 --- a/tools/testing/selftests/kselftest_harness.h +++ b/tools/testing/selftests/kselftest_harness.h @@ -56,6 +56,7 @@ #include <asm/types.h> #include <ctype.h> #include <errno.h> +#include <linux/overflow.h> #include <linux/unistd.h> #include <poll.h> #include <stdbool.h> @@ -751,7 +752,7 @@ for (; _metadata->trigger; _metadata->trigger = \ __bail(_assert, _metadata)) -#define is_signed_type(var) (!!(((__typeof__(var))(-1)) < (__typeof__(var))1)) +#define is_signed_var(var) is_signed_type(__typeof__(var)) #define __EXPECT(_expected, _expected_str, _seen, _seen_str, _t, _assert) do { \ /* Avoid multiple evaluation of the cases */ \ @@ -759,7 +760,7 @@ __typeof__(_seen) __seen = (_seen); \ if (!(__exp _t __seen)) { \ /* Report with actual signedness to avoid weird output. */ \ - switch (is_signed_type(__exp) * 2 + is_signed_type(__seen)) { \ + switch (is_signed_var(__exp) * 2 + is_signed_var(__seen)) { \ case 0: { \ uintmax_t __exp_print = (uintmax_t)__exp; \ uintmax_t __seen_print = (uintmax_t)__seen; \ base-commit: 78f4e737a53e1163ded2687a922fce138aee73f5 -- 2.50.0.714.g196bf9f422-goog

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