From 22098763a10d9c1340827fcf6edab66f153b27f0 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 13 Sep 2026 12:27:00 -0700 Subject: Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Don't destroy user event fields when removal fails User event fields are destroyed before the event is removed from visibility. But that can fail leaving the still visible event with no fields. Move the destroying of the fields to after the event is successfully removed from visibility. - Initialize function graph state is fork before calling copy_exec_state() For non-CLONE_VM forks, copy_exec_state() allocates a new task_exec_state. If that allocation fails, ftrace_graph_exit_task() will free the tasks ret_stack pointer. Since that pointer is still using the parent's ret_stack, it mistakenly frees the parent's pointer too. Call ftrace_graph_init() on the task first which will NULL out the new tasks's ret_stack and if the copy fails, it will not free anything. - Remove FGRAPH_MAX_INDEX The macro FGRAPH_MAX_INDEX was added but never used. Remove it. - Save ent_size in function graph printing of nested functions The function graph tracer needs to look at the next event to see if the next event is the return of the current function entry. If it is, it prints a single line: ktime_get(); Otherwise it prints it like a nested function: tick_nohz_irq_exit() { ktime_get(); kcpustat_irq_exit(); } In order to look at the next event, it must save the current event so that it has the information to print from it. It saves the event in the iterator descriptor called "ent". What it doesn't save is the ent_size of the event which is now used to know if the function graph arguments are to be printed. The peek doesn't save the size so the size used happens to be that of the size of the last event that was seen. Save the entry event size in the iterator descriptor so that the correct size is used. - Fix several errors with freeing data in the histogram code The histogram code had a lot of leaked or or incorrect accounting when failures happen. Correct them. - Fix histogram regression of .percent and .graph modifiers Up until 6.3 histogram values could have "percent" or "graph" modifiers that changed how they were printed. But a change that added restricting histograms values from being strings, stack traces and other modifiers inadvertently prevented them from using the percent and graph modifiers, which were legal use cases for values. Put back the percent and graph modifiers. - Fix various typos in the comments - Set the trace_clock before initializing a histogram with clock argument The histogram API allows the user to specific which trace clock to use via a "clock=" string. The histogram is set up first before the clock is checked. If the passed in clock is not valid, it exits without fully fixing up the histogram leaving it on the list and a use-after-free can trigger. Update the clock argument first and if it fails then exit gracefully before the histogram trigger is placed on any lists. - Restore :mod: trailer after parsing in ftrace_set_clr_event The function ftrace_set_clr_event() modifies the parse string and needs to put it back to what was passed in. It searches for ":mod:" via a strsep() but fails to put back the first ':' in the string. Add back the ':' in the passed in string. - Take trace_array reference when opening a tracer options file The options files are dynamically created and some tracers add their own options. When a tracer adds their own list of options, the trace_array holding them has an array to hold the list of options for each tracer. This array increases in size via a krealloc(), and the new entry gets a newly allocated array to hold the options of the new tracer being added. The element in each entry of the tracer's option array holds a pointer back to the trace_array, a pointer to the tracer it is associated to, a pointer to the flags of the option. The issue is that these arrays are freed when the trace_array is freed when its instance it represents is removed from the instances directory. There's a race that an open of one of these options files can happen when the instance is being removed. Add a new helper function to be called by the open function of the options file to iterate all existing trace_arrays under a lock and find the one that has the given option element in one of it's tracer arrays. If found, then update the associated trace_array's reference counter to keep it from being freed. If not found, have the open call return -ENODEV. - Disable interrupts when acquiring the lock in rb_wake_up_waiters() The function rb_wake_up_waiters() assumes it will be called in interrupt context and does not disable irqs when taking cpu_buffer->reader_lock, which can be called in hard interrupt context. The issue is in PREEMPT_RT, this function is called in thread context leaving this lock open to a deadlock. Take the lock with interrupts disabled. - Use rcu_assign_pointer() for tmp_ops filter hash The tmp_ops used in update_ftrace_direct_mod() assigns its filter_hash field directly, but that field is annotated as __rcu and sparse complains. Assign it with rcu_assign_pointer() - Fix use-after-free in enable_trigger_private_data_free() The trace_event_call is accessed through the event_trigger_data's trace_event_file pointer to put the trace_event_call on freeing. The issue is that the trace_event_file data may have been freed already causing a use-after-free. Add a field to the event_trigger_data that points directly to the trace_event_call so that it can decrement its reference directly without needing to go through the trace_event_file. - Fix accounting of buffer data remote headers trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount the number of pages is needed for the asked for size as it doesn't take into account the meta data on each page. Add a helper function to do the calculation properly and use that in these functions. - Catch nr_page_va overflow in ring_buffer_desc sizing The number of pages per remote ring buffer is capped by ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to overflow that field would silently allocate a descriptor smaller than what was asked for. - Do not resize the subbuf order if any per_cpu buffer is disabled The mmapping of ring buffers disables resizing the subbuffers, but it is done per-cpu whereas the subbuf size change is done for all the per_cpu buffers under the buffer->mutex. It could change the size of some while the mapping is happening on others. Have the resize of the subbuf order check all the per_cpu buffers under the lock to see if any of them is disabled before starting and causing an inconsistency between buffers that are being mapped. * tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits) ring-buffer: Check resize_disabled before publishing the new subbuf order tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing tracing/remotes: Account for ring buffer page header in size calculation tracing: Don't dereference trace_event_file in deferred trigger free ftrace: Use rcu_assign_pointer() for tmp_ops filter hash ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters() tracing: Take trace_array reference when opening a tracer options file tracing: Fix ring_buffer_read_page_size() kernel-doc tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event() tracing: Fix memory corruption from a "STACKTRACE" histogram key tracing: Fix memory corruption from the histogram stacktrace modifier tracing: Undo the registration when enabling the histogram trigger fails tracing: Take the reference before publishing the named histogram trigger tracing: Set the trace clock before registering the histogram trigger tracing: Fix typo "preceeded" in comment tracing: Fix typo "availabe" in comment tracing: Let histogram values keep the percent and graph modifiers tracing: Keep the entry count when the histogram stats allocation fails tracing: Free histogram the field rejected for a bad modifier tracing: Free histogram the var ref when its initialization fails ... --- tools/testing/selftests/tty/.gitignore | 3 + tools/testing/selftests/tty/Makefile | 9 + tools/testing/selftests/tty/config | 1 + tools/testing/selftests/tty/tty_tiocsti_test.c | 650 ++++++++++++++++++++++++ tools/testing/selftests/tty/tty_tstamp_update.c | 106 ++++ 5 files changed, 769 insertions(+) create mode 100644 tools/testing/selftests/tty/.gitignore create mode 100644 tools/testing/selftests/tty/Makefile create mode 100644 tools/testing/selftests/tty/config create mode 100644 tools/testing/selftests/tty/tty_tiocsti_test.c create mode 100644 tools/testing/selftests/tty/tty_tstamp_update.c (limited to 'tools/testing/selftests/tty') diff --git a/tools/testing/selftests/tty/.gitignore b/tools/testing/selftests/tty/.gitignore new file mode 100644 index 000000000..2453685d2 --- /dev/null +++ b/tools/testing/selftests/tty/.gitignore @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0-only +tty_tiocsti_test +tty_tstamp_update diff --git a/tools/testing/selftests/tty/Makefile b/tools/testing/selftests/tty/Makefile new file mode 100644 index 000000000..7f6fbe5a0 --- /dev/null +++ b/tools/testing/selftests/tty/Makefile @@ -0,0 +1,9 @@ +# SPDX-License-Identifier: GPL-2.0 +CFLAGS = -O2 -Wall +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 000000000..c6373aba6 --- /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 000000000..5e767e6cb --- /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 + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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 diff --git a/tools/testing/selftests/tty/tty_tstamp_update.c b/tools/testing/selftests/tty/tty_tstamp_update.c new file mode 100644 index 000000000..bc3291dcd --- /dev/null +++ b/tools/testing/selftests/tty/tty_tstamp_update.c @@ -0,0 +1,106 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include +#include +#include +#include +#include + +#include "kselftest.h" + +#define MIN_TTY_PATH_LEN 8 + +static bool tty_valid(char *tty) +{ + if (strlen(tty) < MIN_TTY_PATH_LEN) + return false; + + if (strncmp(tty, "/dev/tty", MIN_TTY_PATH_LEN) == 0 || + strncmp(tty, "/dev/pts", MIN_TTY_PATH_LEN) == 0) + return true; + + return false; +} + +static int write_dev_tty(void) +{ + FILE *f; + int r = 0; + + f = fopen("/dev/tty", "r+"); + if (!f) + return -errno; + + r = fprintf(f, "hello, world!\n"); + if (r != strlen("hello, world!\n")) + r = -EIO; + + fclose(f); + return r; +} + +int main(int argc, char **argv) +{ + int r; + char tty[PATH_MAX] = {}; + struct stat st1, st2; + int result = KSFT_FAIL; + + ksft_print_header(); + ksft_set_plan(1); + + r = readlink("/proc/self/fd/0", tty, PATH_MAX); + if (r < 0) { + ksft_print_msg("readlink on /proc/self/fd/0 failed: %m\n"); + goto out; + } + + if (!tty_valid(tty)) { + ksft_print_msg("invalid tty path '%s'\n", tty); + result = KSFT_SKIP; + goto out; + + } + + r = stat(tty, &st1); + if (r < 0) { + ksft_print_msg("stat failed on tty path '%s': %m\n", tty); + goto out; + } + + /* We need to wait at least 8 seconds in order to observe timestamp change */ + /* https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fbf47635315ab308c9b58a1ea0906e711a9228de */ + sleep(10); + + r = write_dev_tty(); + if (r < 0) { + ksft_print_msg("failed to write to /dev/tty: %s\n", + strerror(-r)); + goto out; + } + + r = stat(tty, &st2); + if (r < 0) { + ksft_print_msg("stat failed on tty path '%s': %m\n", tty); + goto out; + } + + /* We wrote to the terminal so timestamps should have been updated */ + if (st1.st_atim.tv_sec == st2.st_atim.tv_sec && + st1.st_mtim.tv_sec == st2.st_mtim.tv_sec) { + ksft_print_msg("tty timestamps not updated\n"); + goto out; + } + + ksft_print_msg( + "timestamps of terminal '%s' updated after write to /dev/tty\n", tty); + result = KSFT_PASS; + +out: + ksft_test_result_report(result, "tty_tstamp_update\n"); + + ksft_finished(); +} -- cgit v1.3.1