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a=ed25519-sha256; t=1787560731; l=10996; i=andrea.cervesato@suse.com; s=20251210; h=from:subject:message-id; bh=6mWut0+rdYhLxpTLjMN2Os9sbmDDz9McaJDWOXXRjmQ=; b=6HvblsPuOGcmHPhEVySo4shSU7ivBTLEtMhNsKHVHjRRck2zQ9vIuJKX2ZN7wy5wQuyU/kGj2 STfJOD6/TBKA9vt+ian+XeC6FYKLpONXE0RTdEGU/Y4eNS+g8bavB1e X-Developer-Key: i=andrea.cervesato@suse.com; a=ed25519; pk=zKY+6GCauOiuHNZ//d8PQ/UL4jFCTKbXrzXAOQSLevI= X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.999]; MIME_GOOD(-0.10)[text/plain]; RCPT_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_DN_ALL(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo, suse.com:mid, suse.com:email] X-Virus-Scanned: clamav-milter 1.0.9 at in-6.smtp.seeweb.it X-Virus-Status: Clean Subject: [LTP] [PATCH v2] coredump01: New core_pattern specifiers test X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" From: Andrea Cervesato LTP has no coverage for the core_pattern specifiers expansion, neither for the pipe flavor of core_pattern, where the kernel spawns a user space helper and writes the core dump into its standard input. The new test verifies that %e, %p and %s are expanded both in the core file name and in the arguments of a piped helper, checking also that the helper really receives an ELF core dump. Root is required to rewrite the system wide core_pattern, which is restored by the test library on all exit paths. Signed-off-by: Andrea Cervesato --- Add a simple coredump01 test that simulate a coredump and verify that it actually works. This is a small coverage that is missing inside LTP testing suite. --- Changes in v2: - fix CI agent spotted errors - Link to v1: https://lore.kernel.org/20260820-coredump-v1-1-7ce51603cefb@suse.com --- runtest/kernel_misc | 1 + testcases/kernel/Makefile | 1 + testcases/kernel/coredump/.gitignore | 2 + testcases/kernel/coredump/Makefile | 7 + testcases/kernel/coredump/coredump01.c | 221 ++++++++++++++++++++++++++ testcases/kernel/coredump/coredump01_helper.c | 66 ++++++++ 6 files changed, 298 insertions(+) diff --git a/runtest/kernel_misc b/runtest/kernel_misc index cc3562cb7..ecf9ee2a2 100644 --- a/runtest/kernel_misc +++ b/runtest/kernel_misc @@ -17,3 +17,4 @@ zram02 zram02.sh zram03 zram03 umip_basic_test umip_basic_test aslr01 aslr01 +coredump01 coredump01 diff --git a/testcases/kernel/Makefile b/testcases/kernel/Makefile index ac816e4e8..6b303c14b 100644 --- a/testcases/kernel/Makefile +++ b/testcases/kernel/Makefile @@ -19,6 +19,7 @@ SUBDIRS += lib SUBDIRS += connectors \ containers \ controllers \ + coredump \ crypto \ device-drivers \ firmware \ diff --git a/testcases/kernel/coredump/.gitignore b/testcases/kernel/coredump/.gitignore new file mode 100644 index 000000000..cd0b51700 --- /dev/null +++ b/testcases/kernel/coredump/.gitignore @@ -0,0 +1,2 @@ +/coredump01 +/coredump01_helper diff --git a/testcases/kernel/coredump/Makefile b/testcases/kernel/coredump/Makefile new file mode 100644 index 000000000..951a3e976 --- /dev/null +++ b/testcases/kernel/coredump/Makefile @@ -0,0 +1,7 @@ +# SPDX-License-Identifier: GPL-2.0-or-later +# Copyright (c) 2026 Linux Test Project + +top_srcdir ?= ../../.. + +include $(top_srcdir)/include/mk/testcases.mk +include $(top_srcdir)/include/mk/generic_leaf_target.mk diff --git a/testcases/kernel/coredump/coredump01.c b/testcases/kernel/coredump/coredump01.c new file mode 100644 index 000000000..a958d8307 --- /dev/null +++ b/testcases/kernel/coredump/coredump01.c @@ -0,0 +1,221 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2026 Linux Test Project + */ + +/*\ + * Verify that the kernel expands the :manpage:`core(5)` specifiers %e + * (executable name), %p (PID) and %s (signal number) when it creates a + * core dump. + * + * Both flavors of ``/proc/sys/kernel/core_pattern`` are tested: + * + * - a plain file name, where the specifiers become part of the core file + * name + * - a pipe to a user space helper, where the specifiers are expanded in + * the helper arguments and the core dump is written to the helper + * standard input + * + * The test needs root because it rewrites the system wide core_pattern. + * The original value is saved and restored by the test library on all + * exit paths. + * + * [Algorithm] + * + * - Point core_pattern into the test temporary directory + * - Fork a child which aborts itself to produce a core dump + * - For the file pattern check that ``core...`` was created + * - For the pipe pattern check the arguments the helper was called with + * and that it received an ELF core dump on its standard input + */ + +#include +#include +#include + +#include "tst_test.h" +#include "tst_kconfig.h" +#include "lapi/prctl.h" + +#define PATTERN_MAX 128 +#define HELPER "coredump01_helper" +#define HELPER_TIMEOUT 10 + +static char helper_dir[PATH_MAX]; +static char cwd[PATH_MAX]; + +static void set_pattern(const char *fmt, ...) +{ + char pattern[PATTERN_MAX]; + va_list va; + int len; + + va_start(va, fmt); + len = vsnprintf(pattern, sizeof(pattern), fmt, va); + va_end(va); + + if (len >= PATTERN_MAX) + tst_brk(TCONF, "core_pattern does not fit into %i bytes", PATTERN_MAX - 1); + + SAFE_FILE_PRINTF(PATH_KERN_CORE_PATTERN, "%s", pattern); + + tst_res(TINFO, "core_pattern is '%s'", pattern); +} + +static pid_t crash_child(void) +{ + int status; + pid_t pid; + + pid = SAFE_FORK(); + if (!pid) + abort(); + + SAFE_WAITPID(pid, &status, 0); + + if (!WIFSIGNALED(status) || !WCOREDUMP(status)) + tst_brk(TFAIL, "Child did not dump core"); + + return pid; +} + +static void verify_file_pattern(void) +{ + char dump[PATH_MAX + 32]; + pid_t pid; + + tst_res(TINFO, "Testing file core_pattern"); + + set_pattern("%s/core.%%e.%%p.%%s", cwd); + + pid = crash_child(); + + snprintf(dump, sizeof(dump), "%s/core.coredump01.%d.%d", cwd, pid, SIGABRT); + + TST_EXP_PASS(access(dump, F_OK), "core.%%e.%%p.%%s expanded to core.coredump01.%d.%d", + pid, SIGABRT); +} + +/* PID 2 is kthreadd only if we can see the initial PID namespace */ +static int have_init_pid_ns(void) +{ + char comm[16] = {0}; + int fd, len; + + fd = open("/proc/2/comm", O_RDONLY); + if (fd < 0) + return 0; + + len = SAFE_READ(0, fd, comm, sizeof(comm) - 1); + SAFE_CLOSE(fd); + + return len > 0 && !strncmp(comm, "kthreadd\n", 9); +} + +/* + * The kernel resolves @path the way /proc/2/root (kthreadd lives in the + * initial namespaces) resolves it. + */ +static int same_in_init_mnt_ns(const char *path) +{ + char init_path[PATH_MAX + 32]; + struct stat our_st, init_st; + + SAFE_STAT(path, &our_st); + + snprintf(init_path, sizeof(init_path), "/proc/2/root%s", path); + + if (stat(init_path, &init_st)) + return 0; + + return init_st.st_dev == our_st.st_dev && init_st.st_ino == our_st.st_ino; +} + +static void verify_pipe_pattern(void) +{ + char res[PATH_MAX + 32], exe[PATH_MAX], helper[PATH_MAX + 32]; + struct tst_kconfig_var kconfig = TST_KCONFIG_INIT("CONFIG_STATIC_USERMODEHELPER"); + int pid_seen, sig_seen, elf; + long long bytes; + pid_t pid; + + tst_kconfig_read(&kconfig, 1); + if (kconfig.choice == 'y') { + tst_res(TCONF, "CONFIG_STATIC_USERMODEHELPER is enabled, skipping pipe core_pattern"); + return; + } + + snprintf(helper, sizeof(helper), "%s/%s", helper_dir, HELPER); + + /* + * The kernel always execs the pipe helper in the initial mount + * namespace (core(5)), no matter where the crashing process lives. + * Skip unless both the helper and the result directory are the very + * same objects there, otherwise the kernel would not find them and + * the test would fail spuriously, e.g. inside a container. + */ + if (!have_init_pid_ns() || !same_in_init_mnt_ns(helper) || + !same_in_init_mnt_ns(cwd)) { + tst_res(TCONF, "Pipe helper or result dir not visible in the initial mount namespace"); + return; + } + + tst_res(TINFO, "Testing pipe core_pattern"); + + set_pattern("|%s/%s %%e %%p %%s %s/res.%%p", helper_dir, HELPER, cwd); + + pid = crash_child(); + + snprintf(res, sizeof(res), "%s/res.%d", cwd, pid); + + /* the kernel spawns the helper asynchronously */ + if (TST_RETRY_FN_EXP_BACKOFF(access(res, F_OK), TST_RETVAL_EQ0, HELPER_TIMEOUT)) { + tst_res(TFAIL, "%s did not report any core dump", HELPER); + return; + } + + SAFE_FILE_SCANF(res, "exe=%15s pid=%d sig=%d bytes=%lld elf=%d", + exe, &pid_seen, &sig_seen, &bytes, &elf); + + TST_EXP_EQ_STR(exe, "coredump01"); + TST_EXP_EQ_LI(pid_seen, pid); + TST_EXP_EQ_LI(sig_seen, SIGABRT); + TST_EXP_EXPR(elf && bytes > 0, "%s read %lli bytes of ELF core dump", HELPER, bytes); +} + +static void run(unsigned int n) +{ + if (n) + verify_pipe_pattern(); + else + verify_file_pattern(); +} + +static void setup(void) +{ + struct rlimit rl = {RLIM_INFINITY, RLIM_INFINITY}; + ssize_t len; + + SAFE_SETRLIMIT(RLIMIT_CORE, &rl); + + SAFE_PRCTL(PR_SET_DUMPABLE, 1, 0, 0, 0); + + SAFE_GETCWD(cwd, sizeof(cwd)); + + len = SAFE_READLINK("/proc/self/exe", helper_dir, sizeof(helper_dir) - 1); + helper_dir[len] = '\0'; + *strrchr(helper_dir, '/') = '\0'; +} + +static struct tst_test test = { + .test = run, + .tcnt = 2, + .setup = setup, + .needs_root = 1, + .needs_tmpdir = 1, + .forks_child = 1, + .save_restore = (const struct tst_path_val[]) { + {PATH_KERN_CORE_PATTERN, NULL, TST_SR_TCONF}, + {} + }, +}; diff --git a/testcases/kernel/coredump/coredump01_helper.c b/testcases/kernel/coredump/coredump01_helper.c new file mode 100644 index 000000000..41091b428 --- /dev/null +++ b/testcases/kernel/coredump/coredump01_helper.c @@ -0,0 +1,66 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2026 Linux Test Project + */ + +/* + * Core dump collector for the piped core_pattern tested by coredump01. + * + * Avoiding the LTP API here is correct, since the kernel spawns the helper + * through ``call_usermodehelper()`` without the LTP IPC environment. + * + * The helper is called as: + * + * coredump01_helper + * + * and stores what it received in the result file, which is published with + * :manpage:`rename()` so that the polling test never reads a partial line. + */ + +#include +#include +#include +#include +#include + +int main(int argc, char *argv[]) +{ + char buf[4096], tmp[PATH_MAX], magic[4]; + long long bytes = 0; + ssize_t rval, i; + int fd, elf = 0; + + if (argc < 5) + return 1; + + /* + * A core dump embeds the ELF images it has mapped, so the magic is + * only meaningful at the very beginning of the stream. Collect it + * across reads, since a pipe read can return less than 4 bytes. + */ + while ((rval = read(STDIN_FILENO, buf, sizeof(buf))) > 0) { + for (i = 0; i < rval && bytes + i < 4; i++) + magic[bytes + i] = buf[i]; + + bytes += rval; + } + + if (rval < 0) + return 1; + + if (bytes >= 4 && !memcmp(magic, "\177ELF", 4)) + elf = 1; + + snprintf(tmp, sizeof(tmp), "%s.tmp", argv[4]); + + fd = open(tmp, O_WRONLY | O_CREAT | O_TRUNC, 0644); + if (fd < 0) + return 1; + + dprintf(fd, "exe=%s pid=%s sig=%s bytes=%lld elf=%d\n", + argv[1], argv[2], argv[3], bytes, elf); + + close(fd); + + return rename(tmp, argv[4]) ? 1 : 0; +} --- base-commit: e62b1a4731f9c458d65c2659d2f8bb58b93e6d6d change-id: 20260820-coredump-22fc731bde08 Best regards, -- Andrea Cervesato -- Mailing list info: https://lists.linux.it/listinfo/ltp