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Diffstat (limited to 'src/basic/process-util.c')
| -rw-r--r-- | src/basic/process-util.c | 1565 |
1 files changed, 1565 insertions, 0 deletions
diff --git a/src/basic/process-util.c b/src/basic/process-util.c new file mode 100644 index 0000000..78ce43b --- /dev/null +++ b/src/basic/process-util.c @@ -0,0 +1,1565 @@ +/* SPDX-License-Identifier: LGPL-2.1+ */ + +#include <ctype.h> +#include <errno.h> +#include <limits.h> +#include <linux/oom.h> +#include <sched.h> +#include <signal.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdio_ext.h> +#include <stdlib.h> +#include <string.h> +#include <sys/mman.h> +#include <sys/mount.h> +#include <sys/personality.h> +#include <sys/prctl.h> +#include <sys/types.h> +#include <sys/wait.h> +#include <syslog.h> +#include <unistd.h> +#if HAVE_VALGRIND_VALGRIND_H +#include <valgrind/valgrind.h> +#endif + +#include "alloc-util.h" +#include "architecture.h" +#include "escape.h" +#include "fd-util.h" +#include "fileio.h" +#include "fs-util.h" +#include "ioprio.h" +#include "log.h" +#include "macro.h" +#include "missing.h" +#include "process-util.h" +#include "raw-clone.h" +#include "rlimit-util.h" +#include "signal-util.h" +#include "stat-util.h" +#include "string-table.h" +#include "string-util.h" +#include "terminal-util.h" +#include "user-util.h" +#include "util.h" + +int get_process_state(pid_t pid) { + const char *p; + char state; + int r; + _cleanup_free_ char *line = NULL; + + assert(pid >= 0); + + p = procfs_file_alloca(pid, "stat"); + + r = read_one_line_file(p, &line); + if (r == -ENOENT) + return -ESRCH; + if (r < 0) + return r; + + p = strrchr(line, ')'); + if (!p) + return -EIO; + + p++; + + if (sscanf(p, " %c", &state) != 1) + return -EIO; + + return (unsigned char) state; +} + +int get_process_comm(pid_t pid, char **ret) { + _cleanup_free_ char *escaped = NULL, *comm = NULL; + const char *p; + int r; + + assert(ret); + assert(pid >= 0); + + escaped = new(char, TASK_COMM_LEN); + if (!escaped) + return -ENOMEM; + + p = procfs_file_alloca(pid, "comm"); + + r = read_one_line_file(p, &comm); + if (r == -ENOENT) + return -ESRCH; + if (r < 0) + return r; + + /* Escape unprintable characters, just in case, but don't grow the string beyond the underlying size */ + cellescape(escaped, TASK_COMM_LEN, comm); + + *ret = TAKE_PTR(escaped); + return 0; +} + +int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char **line) { + _cleanup_fclose_ FILE *f = NULL; + bool space = false; + char *k; + _cleanup_free_ char *ans = NULL; + const char *p; + int c; + + assert(line); + assert(pid >= 0); + + /* Retrieves a process' command line. Replaces unprintable characters while doing so by whitespace (coalescing + * multiple sequential ones into one). If max_length is != 0 will return a string of the specified size at most + * (the trailing NUL byte does count towards the length here!), abbreviated with a "..." ellipsis. If + * comm_fallback is true and the process has no command line set (the case for kernel threads), or has a + * command line that resolves to the empty string will return the "comm" name of the process instead. + * + * Returns -ESRCH if the process doesn't exist, and -ENOENT if the process has no command line (and + * comm_fallback is false). Returns 0 and sets *line otherwise. */ + + p = procfs_file_alloca(pid, "cmdline"); + + f = fopen(p, "re"); + if (!f) { + if (errno == ENOENT) + return -ESRCH; + return -errno; + } + + (void) __fsetlocking(f, FSETLOCKING_BYCALLER); + + if (max_length == 0) { + /* This is supposed to be a safety guard against runaway command lines. */ + long l = sysconf(_SC_ARG_MAX); + assert(l > 0); + max_length = l; + } + + if (max_length == 1) { + + /* If there's only room for one byte, return the empty string */ + ans = new0(char, 1); + if (!ans) + return -ENOMEM; + + *line = TAKE_PTR(ans); + return 0; + + } else { + bool dotdotdot = false; + size_t left; + + ans = new(char, max_length); + if (!ans) + return -ENOMEM; + + k = ans; + left = max_length; + while ((c = getc(f)) != EOF) { + + if (isprint(c)) { + + if (space) { + if (left <= 2) { + dotdotdot = true; + break; + } + + *(k++) = ' '; + left--; + space = false; + } + + if (left <= 1) { + dotdotdot = true; + break; + } + + *(k++) = (char) c; + left--; + } else if (k > ans) + space = true; + } + + if (dotdotdot) { + if (max_length <= 4) { + k = ans; + left = max_length; + } else { + k = ans + max_length - 4; + left = 4; + + /* Eat up final spaces */ + while (k > ans && isspace(k[-1])) { + k--; + left++; + } + } + + strncpy(k, "...", left-1); + k[left-1] = 0; + } else + *k = 0; + } + + /* Kernel threads have no argv[] */ + if (isempty(ans)) { + _cleanup_free_ char *t = NULL; + int h; + + ans = mfree(ans); + + if (!comm_fallback) + return -ENOENT; + + h = get_process_comm(pid, &t); + if (h < 0) + return h; + + size_t l = strlen(t); + + if (l + 3 <= max_length) { + ans = strjoin("[", t, "]"); + if (!ans) + return -ENOMEM; + + } else if (max_length <= 6) { + ans = new(char, max_length); + if (!ans) + return -ENOMEM; + + memcpy(ans, "[...]", max_length-1); + ans[max_length-1] = 0; + } else { + t[max_length - 6] = 0; + + /* Chop off final spaces */ + delete_trailing_chars(t, WHITESPACE); + + ans = strjoin("[", t, "...]"); + if (!ans) + return -ENOMEM; + } + + *line = TAKE_PTR(ans); + return 0; + } + + k = realloc(ans, strlen(ans) + 1); + if (!k) + return -ENOMEM; + + ans = NULL; + *line = k; + + return 0; +} + +int rename_process(const char name[]) { + static size_t mm_size = 0; + static char *mm = NULL; + bool truncated = false; + size_t l; + + /* This is a like a poor man's setproctitle(). It changes the comm field, argv[0], and also the glibc's + * internally used name of the process. For the first one a limit of 16 chars applies; to the second one in + * many cases one of 10 (i.e. length of "/sbin/init") — however if we have CAP_SYS_RESOURCES it is unbounded; + * to the third one 7 (i.e. the length of "systemd". If you pass a longer string it will likely be + * truncated. + * + * Returns 0 if a name was set but truncated, > 0 if it was set but not truncated. */ + + if (isempty(name)) + return -EINVAL; /* let's not confuse users unnecessarily with an empty name */ + + if (!is_main_thread()) + return -EPERM; /* Let's not allow setting the process name from other threads than the main one, as we + * cache things without locking, and we make assumptions that PR_SET_NAME sets the + * process name that isn't correct on any other threads */ + + l = strlen(name); + + /* First step, change the comm field. The main thread's comm is identical to the process comm. This means we + * can use PR_SET_NAME, which sets the thread name for the calling thread. */ + if (prctl(PR_SET_NAME, name) < 0) + log_debug_errno(errno, "PR_SET_NAME failed: %m"); + if (l >= TASK_COMM_LEN) /* Linux process names can be 15 chars at max */ + truncated = true; + + /* Second step, change glibc's ID of the process name. */ + if (program_invocation_name) { + size_t k; + + k = strlen(program_invocation_name); + strncpy(program_invocation_name, name, k); + if (l > k) + truncated = true; + } + + /* Third step, completely replace the argv[] array the kernel maintains for us. This requires privileges, but + * has the advantage that the argv[] array is exactly what we want it to be, and not filled up with zeros at + * the end. This is the best option for changing /proc/self/cmdline. */ + + /* Let's not bother with this if we don't have euid == 0. Strictly speaking we should check for the + * CAP_SYS_RESOURCE capability which is independent of the euid. In our own code the capability generally is + * present only for euid == 0, hence let's use this as quick bypass check, to avoid calling mmap() if + * PR_SET_MM_ARG_{START,END} fails with EPERM later on anyway. After all geteuid() is dead cheap to call, but + * mmap() is not. */ + if (geteuid() != 0) + log_debug("Skipping PR_SET_MM, as we don't have privileges."); + else if (mm_size < l+1) { + size_t nn_size; + char *nn; + + nn_size = PAGE_ALIGN(l+1); + nn = mmap(NULL, nn_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); + if (nn == MAP_FAILED) { + log_debug_errno(errno, "mmap() failed: %m"); + goto use_saved_argv; + } + + strncpy(nn, name, nn_size); + + /* Now, let's tell the kernel about this new memory */ + if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, (unsigned long) nn, 0, 0) < 0) { + /* HACK: prctl() API is kind of dumb on this point. The existing end address may already be + * below the desired start address, in which case the kernel may have kicked this back due + * to a range-check failure (see linux/kernel/sys.c:validate_prctl_map() to see this in + * action). The proper solution would be to have a prctl() API that could set both start+end + * simultaneously, or at least let us query the existing address to anticipate this condition + * and respond accordingly. For now, we can only guess at the cause of this failure and try + * a workaround--which will briefly expand the arg space to something potentially huge before + * resizing it to what we want. */ + log_debug_errno(errno, "PR_SET_MM_ARG_START failed, attempting PR_SET_MM_ARG_END hack: %m"); + + if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long) nn + l + 1, 0, 0) < 0) { + log_debug_errno(errno, "PR_SET_MM_ARG_END hack failed, proceeding without: %m"); + (void) munmap(nn, nn_size); + goto use_saved_argv; + } + + if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, (unsigned long) nn, 0, 0) < 0) { + log_debug_errno(errno, "PR_SET_MM_ARG_START still failed, proceeding without: %m"); + goto use_saved_argv; + } + } else { + /* And update the end pointer to the new end, too. If this fails, we don't really know what + * to do, it's pretty unlikely that we can rollback, hence we'll just accept the failure, + * and continue. */ + if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long) nn + l + 1, 0, 0) < 0) + log_debug_errno(errno, "PR_SET_MM_ARG_END failed, proceeding without: %m"); + } + + if (mm) + (void) munmap(mm, mm_size); + + mm = nn; + mm_size = nn_size; + } else { + strncpy(mm, name, mm_size); + + /* Update the end pointer, continuing regardless of any failure. */ + if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long) mm + l + 1, 0, 0) < 0) + log_debug_errno(errno, "PR_SET_MM_ARG_END failed, proceeding without: %m"); + } + +use_saved_argv: + /* Fourth step: in all cases we'll also update the original argv[], so that our own code gets it right too if + * it still looks here */ + + if (saved_argc > 0) { + int i; + + if (saved_argv[0]) { + size_t k; + + k = strlen(saved_argv[0]); + strncpy(saved_argv[0], name, k); + if (l > k) + truncated = true; + } + + for (i = 1; i < saved_argc; i++) { + if (!saved_argv[i]) + break; + + memzero(saved_argv[i], strlen(saved_argv[i])); + } + } + + return !truncated; +} + +int is_kernel_thread(pid_t pid) { + _cleanup_free_ char *line = NULL; + unsigned long long flags; + size_t l, i; + const char *p; + char *q; + int r; + + if (IN_SET(pid, 0, 1) || pid == getpid_cached()) /* pid 1, and we ourselves certainly aren't a kernel thread */ + return 0; + if (!pid_is_valid(pid)) + return -EINVAL; + + p = procfs_file_alloca(pid, "stat"); + r = read_one_line_file(p, &line); + if (r == -ENOENT) + return -ESRCH; + if (r < 0) + return r; + + /* Skip past the comm field */ + q = strrchr(line, ')'); + if (!q) + return -EINVAL; + q++; + + /* Skip 6 fields to reach the flags field */ + for (i = 0; i < 6; i++) { + l = strspn(q, WHITESPACE); + if (l < 1) + return -EINVAL; + q += l; + + l = strcspn(q, WHITESPACE); + if (l < 1) + return -EINVAL; + q += l; + } + + /* Skip preceding whitespace */ + l = strspn(q, WHITESPACE); + if (l < 1) + return -EINVAL; + q += l; + + /* Truncate the rest */ + l = strcspn(q, WHITESPACE); + if (l < 1) + return -EINVAL; + q[l] = 0; + + r = safe_atollu(q, &flags); + if (r < 0) + return r; + + return !!(flags & PF_KTHREAD); +} + +int get_process_capeff(pid_t pid, char **capeff) { + const char *p; + int r; + + assert(capeff); + assert(pid >= 0); + + p = procfs_file_alloca(pid, "status"); + + r = get_proc_field(p, "CapEff", WHITESPACE, capeff); + if (r == -ENOENT) + return -ESRCH; + + return r; +} + +static int get_process_link_contents(const char *proc_file, char **name) { + int r; + + assert(proc_file); + assert(name); + + r = readlink_malloc(proc_file, name); + if (r == -ENOENT) + return -ESRCH; + if (r < 0) + return r; + + return 0; +} + +int get_process_exe(pid_t pid, char **name) { + const char *p; + char *d; + int r; + + assert(pid >= 0); + + p = procfs_file_alloca(pid, "exe"); + r = get_process_link_contents(p, name); + if (r < 0) + return r; + + d = endswith(*name, " (deleted)"); + if (d) + *d = '\0'; + + return 0; +} + +static int get_process_id(pid_t pid, const char *field, uid_t *uid) { + _cleanup_fclose_ FILE *f = NULL; + const char *p; + int r; + + assert(field); + assert(uid); + + if (pid < 0) + return -EINVAL; + + p = procfs_file_alloca(pid, "status"); + f = fopen(p, "re"); + if (!f) { + if (errno == ENOENT) + return -ESRCH; + return -errno; + } + + (void) __fsetlocking(f, FSETLOCKING_BYCALLER); + + for (;;) { + _cleanup_free_ char *line = NULL; + char *l; + + r = read_line(f, LONG_LINE_MAX, &line); + if (r < 0) + return r; + if (r == 0) + break; + + l = strstrip(line); + + if (startswith(l, field)) { + l += strlen(field); + l += strspn(l, WHITESPACE); + + l[strcspn(l, WHITESPACE)] = 0; + + return parse_uid(l, uid); + } + } + + return -EIO; +} + +int get_process_uid(pid_t pid, uid_t *uid) { + + if (pid == 0 || pid == getpid_cached()) { + *uid = getuid(); + return 0; + } + + return get_process_id(pid, "Uid:", uid); +} + +int get_process_gid(pid_t pid, gid_t *gid) { + + if (pid == 0 || pid == getpid_cached()) { + *gid = getgid(); + return 0; + } + + assert_cc(sizeof(uid_t) == sizeof(gid_t)); + return get_process_id(pid, "Gid:", gid); +} + +int get_process_cwd(pid_t pid, char **cwd) { + const char *p; + + assert(pid >= 0); + + p = procfs_file_alloca(pid, "cwd"); + + return get_process_link_contents(p, cwd); +} + +int get_process_root(pid_t pid, char **root) { + const char *p; + + assert(pid >= 0); + + p = procfs_file_alloca(pid, "root"); + + return get_process_link_contents(p, root); +} + +#define ENVIRONMENT_BLOCK_MAX (5U*1024U*1024U) + +int get_process_environ(pid_t pid, char **env) { + _cleanup_fclose_ FILE *f = NULL; + _cleanup_free_ char *outcome = NULL; + size_t allocated = 0, sz = 0; + const char *p; + int r; + + assert(pid >= 0); + assert(env); + + p = procfs_file_alloca(pid, "environ"); + + f = fopen(p, "re"); + if (!f) { + if (errno == ENOENT) + return -ESRCH; + return -errno; + } + + (void) __fsetlocking(f, FSETLOCKING_BYCALLER); + + for (;;) { + char c; + + if (sz >= ENVIRONMENT_BLOCK_MAX) + return -ENOBUFS; + + if (!GREEDY_REALLOC(outcome, allocated, sz + 5)) + return -ENOMEM; + + r = safe_fgetc(f, &c); + if (r < 0) + return r; + if (r == 0) + break; + + if (c == '\0') + outcome[sz++] = '\n'; + else + sz += cescape_char(c, outcome + sz); + } + + outcome[sz] = '\0'; + *env = TAKE_PTR(outcome); + + return 0; +} + +int get_process_ppid(pid_t pid, pid_t *_ppid) { + int r; + _cleanup_free_ char *line = NULL; + long unsigned ppid; + const char *p; + + assert(pid >= 0); + assert(_ppid); + + if (pid == 0 || pid == getpid_cached()) { + *_ppid = getppid(); + return 0; + } + + p = procfs_file_alloca(pid, "stat"); + r = read_one_line_file(p, &line); + if (r == -ENOENT) + return -ESRCH; + if (r < 0) + return r; + + /* Let's skip the pid and comm fields. The latter is enclosed + * in () but does not escape any () in its value, so let's + * skip over it manually */ + + p = strrchr(line, ')'); + if (!p) + return -EIO; + + p++; + + if (sscanf(p, " " + "%*c " /* state */ + "%lu ", /* ppid */ + &ppid) != 1) + return -EIO; + + if ((long unsigned) (pid_t) ppid != ppid) + return -ERANGE; + + *_ppid = (pid_t) ppid; + + return 0; +} + +int wait_for_terminate(pid_t pid, siginfo_t *status) { + siginfo_t dummy; + + assert(pid >= 1); + + if (!status) + status = &dummy; + + for (;;) { + zero(*status); + + if (waitid(P_PID, pid, status, WEXITED) < 0) { + + if (errno == EINTR) + continue; + + return negative_errno(); + } + + return 0; + } +} + +/* + * Return values: + * < 0 : wait_for_terminate() failed to get the state of the + * process, the process was terminated by a signal, or + * failed for an unknown reason. + * >=0 : The process terminated normally, and its exit code is + * returned. + * + * That is, success is indicated by a return value of zero, and an + * error is indicated by a non-zero value. + * + * A warning is emitted if the process terminates abnormally, + * and also if it returns non-zero unless check_exit_code is true. + */ +int wait_for_terminate_and_check(const char *name, pid_t pid, WaitFlags flags) { + _cleanup_free_ char *buffer = NULL; + siginfo_t status; + int r, prio; + + assert(pid > 1); + + if (!name) { + r = get_process_comm(pid, &buffer); + if (r < 0) + log_debug_errno(r, "Failed to acquire process name of " PID_FMT ", ignoring: %m", pid); + else + name = buffer; + } + + prio = flags & WAIT_LOG_ABNORMAL ? LOG_ERR : LOG_DEBUG; + + r = wait_for_terminate(pid, &status); + if (r < 0) + return log_full_errno(prio, r, "Failed to wait for %s: %m", strna(name)); + + if (status.si_code == CLD_EXITED) { + if (status.si_status != EXIT_SUCCESS) + log_full(flags & WAIT_LOG_NON_ZERO_EXIT_STATUS ? LOG_ERR : LOG_DEBUG, + "%s failed with exit status %i.", strna(name), status.si_status); + else + log_debug("%s succeeded.", name); + + return status.si_status; + + } else if (IN_SET(status.si_code, CLD_KILLED, CLD_DUMPED)) { + + log_full(prio, "%s terminated by signal %s.", strna(name), signal_to_string(status.si_status)); + return -EPROTO; + } + + log_full(prio, "%s failed due to unknown reason.", strna(name)); + return -EPROTO; +} + +/* + * Return values: + * + * < 0 : wait_for_terminate_with_timeout() failed to get the state of the process, the process timed out, the process + * was terminated by a signal, or failed for an unknown reason. + * + * >=0 : The process terminated normally with no failures. + * + * Success is indicated by a return value of zero, a timeout is indicated by ETIMEDOUT, and all other child failure + * states are indicated by error is indicated by a non-zero value. + * + * This call assumes SIGCHLD has been blocked already, in particular before the child to wait for has been forked off + * to remain entirely race-free. + */ +int wait_for_terminate_with_timeout(pid_t pid, usec_t timeout) { + sigset_t mask; + int r; + usec_t until; + + assert_se(sigemptyset(&mask) == 0); + assert_se(sigaddset(&mask, SIGCHLD) == 0); + + /* Drop into a sigtimewait-based timeout. Waiting for the + * pid to exit. */ + until = now(CLOCK_MONOTONIC) + timeout; + for (;;) { + usec_t n; + siginfo_t status = {}; + struct timespec ts; + + n = now(CLOCK_MONOTONIC); + if (n >= until) + break; + + r = sigtimedwait(&mask, NULL, timespec_store(&ts, until - n)) < 0 ? -errno : 0; + /* Assuming we woke due to the child exiting. */ + if (waitid(P_PID, pid, &status, WEXITED|WNOHANG) == 0) { + if (status.si_pid == pid) { + /* This is the correct child.*/ + if (status.si_code == CLD_EXITED) + return (status.si_status == 0) ? 0 : -EPROTO; + else + return -EPROTO; + } + } + /* Not the child, check for errors and proceed appropriately */ + if (r < 0) { + switch (r) { + case -EAGAIN: + /* Timed out, child is likely hung. */ + return -ETIMEDOUT; + case -EINTR: + /* Received a different signal and should retry */ + continue; + default: + /* Return any unexpected errors */ + return r; + } + } + } + + return -EPROTO; +} + +void sigkill_wait(pid_t pid) { + assert(pid > 1); + + if (kill(pid, SIGKILL) >= 0) + (void) wait_for_terminate(pid, NULL); +} + +void sigkill_waitp(pid_t *pid) { + PROTECT_ERRNO; + + if (!pid) + return; + if (*pid <= 1) + return; + + sigkill_wait(*pid); +} + +void sigterm_wait(pid_t pid) { + assert(pid > 1); + + if (kill_and_sigcont(pid, SIGTERM) >= 0) + (void) wait_for_terminate(pid, NULL); +} + +int kill_and_sigcont(pid_t pid, int sig) { + int r; + + r = kill(pid, sig) < 0 ? -errno : 0; + + /* If this worked, also send SIGCONT, unless we already just sent a SIGCONT, or SIGKILL was sent which isn't + * affected by a process being suspended anyway. */ + if (r >= 0 && !IN_SET(sig, SIGCONT, SIGKILL)) + (void) kill(pid, SIGCONT); + + return r; +} + +int getenv_for_pid(pid_t pid, const char *field, char **ret) { + _cleanup_fclose_ FILE *f = NULL; + char *value = NULL; + const char *path; + size_t l, sum = 0; + int r; + + assert(pid >= 0); + assert(field); + assert(ret); + + if (pid == 0 || pid == getpid_cached()) { + const char *e; + + e = getenv(field); + if (!e) { + *ret = NULL; + return 0; + } + + value = strdup(e); + if (!value) + return -ENOMEM; + + *ret = value; + return 1; + } + + if (!pid_is_valid(pid)) + return -EINVAL; + + path = procfs_file_alloca(pid, "environ"); + + f = fopen(path, "re"); + if (!f) { + if (errno == ENOENT) + return -ESRCH; + + return -errno; + } + + (void) __fsetlocking(f, FSETLOCKING_BYCALLER); + + l = strlen(field); + for (;;) { + _cleanup_free_ char *line = NULL; + + if (sum > ENVIRONMENT_BLOCK_MAX) /* Give up searching eventually */ + return -ENOBUFS; + + r = read_nul_string(f, LONG_LINE_MAX, &line); + if (r < 0) + return r; + if (r == 0) /* EOF */ + break; + + sum += r; + + if (strneq(line, field, l) && line[l] == '=') { + value = strdup(line + l + 1); + if (!value) + return -ENOMEM; + + *ret = value; + return 1; + } + } + + *ret = NULL; + return 0; +} + +bool pid_is_unwaited(pid_t pid) { + /* Checks whether a PID is still valid at all, including a zombie */ + + if (pid < 0) + return false; + + if (pid <= 1) /* If we or PID 1 would be dead and have been waited for, this code would not be running */ + return true; + + if (pid == getpid_cached()) + return true; + + if (kill(pid, 0) >= 0) + return true; + + return errno != ESRCH; +} + +bool pid_is_alive(pid_t pid) { + int r; + + /* Checks whether a PID is still valid and not a zombie */ + + if (pid < 0) + return false; + + if (pid <= 1) /* If we or PID 1 would be a zombie, this code would not be running */ + return true; + + if (pid == getpid_cached()) + return true; + + r = get_process_state(pid); + if (IN_SET(r, -ESRCH, 'Z')) + return false; + + return true; +} + +int pid_from_same_root_fs(pid_t pid) { + const char *root; + + if (pid < 0) + return false; + + if (pid == 0 || pid == getpid_cached()) + return true; + + root = procfs_file_alloca(pid, "root"); + + return files_same(root, "/proc/1/root", 0); +} + +bool is_main_thread(void) { + static thread_local int cached = 0; + + if (_unlikely_(cached == 0)) + cached = getpid_cached() == gettid() ? 1 : -1; + + return cached > 0; +} + +_noreturn_ void freeze(void) { + + log_close(); + + /* Make sure nobody waits for us on a socket anymore */ + close_all_fds(NULL, 0); + + sync(); + + /* Let's not freeze right away, but keep reaping zombies. */ + for (;;) { + int r; + siginfo_t si = {}; + + r = waitid(P_ALL, 0, &si, WEXITED); + if (r < 0 && errno != EINTR) + break; + } + + /* waitid() failed with an unexpected error, things are really borked. Freeze now! */ + for (;;) + pause(); +} + +bool oom_score_adjust_is_valid(int oa) { + return oa >= OOM_SCORE_ADJ_MIN && oa <= OOM_SCORE_ADJ_MAX; +} + +unsigned long personality_from_string(const char *p) { + int architecture; + + if (!p) + return PERSONALITY_INVALID; + + /* Parse a personality specifier. We use our own identifiers that indicate specific ABIs, rather than just + * hints regarding the register size, since we want to keep things open for multiple locally supported ABIs for + * the same register size. */ + + architecture = architecture_from_string(p); + if (architecture < 0) + return PERSONALITY_INVALID; + + if (architecture == native_architecture()) + return PER_LINUX; +#ifdef SECONDARY_ARCHITECTURE + if (architecture == SECONDARY_ARCHITECTURE) + return PER_LINUX32; +#endif + + return PERSONALITY_INVALID; +} + +const char* personality_to_string(unsigned long p) { + int architecture = _ARCHITECTURE_INVALID; + + if (p == PER_LINUX) + architecture = native_architecture(); +#ifdef SECONDARY_ARCHITECTURE + else if (p == PER_LINUX32) + architecture = SECONDARY_ARCHITECTURE; +#endif + + if (architecture < 0) + return NULL; + + return architecture_to_string(architecture); +} + +int safe_personality(unsigned long p) { + int ret; + + /* So here's the deal, personality() is weirdly defined by glibc. In some cases it returns a failure via errno, + * and in others as negative return value containing an errno-like value. Let's work around this: this is a + * wrapper that uses errno if it is set, and uses the return value otherwise. And then it sets both errno and + * the return value indicating the same issue, so that we are definitely on the safe side. + * + * See https://github.com/systemd/systemd/issues/6737 */ + + errno = 0; + ret = personality(p); + if (ret < 0) { + if (errno != 0) + return -errno; + + errno = -ret; + } + + return ret; +} + +int opinionated_personality(unsigned long *ret) { + int current; + + /* Returns the current personality, or PERSONALITY_INVALID if we can't determine it. This function is a bit + * opinionated though, and ignores all the finer-grained bits and exotic personalities, only distinguishing the + * two most relevant personalities: PER_LINUX and PER_LINUX32. */ + + current = safe_personality(PERSONALITY_INVALID); + if (current < 0) + return current; + + if (((unsigned long) current & 0xffff) == PER_LINUX32) + *ret = PER_LINUX32; + else + *ret = PER_LINUX; + + return 0; +} + +void valgrind_summary_hack(void) { +#if HAVE_VALGRIND_VALGRIND_H + if (getpid_cached() == 1 && RUNNING_ON_VALGRIND) { + pid_t pid; + pid = raw_clone(SIGCHLD); + if (pid < 0) + log_emergency_errno(errno, "Failed to fork off valgrind helper: %m"); + else if (pid == 0) + exit(EXIT_SUCCESS); + else { + log_info("Spawned valgrind helper as PID "PID_FMT".", pid); + (void) wait_for_terminate(pid, NULL); + } + } +#endif +} + +int pid_compare_func(const pid_t *a, const pid_t *b) { + /* Suitable for usage in qsort() */ + return CMP(*a, *b); +} + +int ioprio_parse_priority(const char *s, int *ret) { + int i, r; + + assert(s); + assert(ret); + + r = safe_atoi(s, &i); + if (r < 0) + return r; + + if (!ioprio_priority_is_valid(i)) + return -EINVAL; + + *ret = i; + return 0; +} + +/* The cached PID, possible values: + * + * == UNSET [0] → cache not initialized yet + * == BUSY [-1] → some thread is initializing it at the moment + * any other → the cached PID + */ + +#define CACHED_PID_UNSET ((pid_t) 0) +#define CACHED_PID_BUSY ((pid_t) -1) + +static pid_t cached_pid = CACHED_PID_UNSET; + +void reset_cached_pid(void) { + /* Invoked in the child after a fork(), i.e. at the first moment the PID changed */ + cached_pid = CACHED_PID_UNSET; +} + +/* We use glibc __register_atfork() + __dso_handle directly here, as they are not included in the glibc + * headers. __register_atfork() is mostly equivalent to pthread_atfork(), but doesn't require us to link against + * libpthread, as it is part of glibc anyway. */ +extern int __register_atfork(void (*prepare) (void), void (*parent) (void), void (*child) (void), void *dso_handle); +extern void* __dso_handle _weak_; + +pid_t getpid_cached(void) { + static bool installed = false; + pid_t current_value; + + /* getpid_cached() is much like getpid(), but caches the value in local memory, to avoid having to invoke a + * system call each time. This restores glibc behaviour from before 2.24, when getpid() was unconditionally + * cached. Starting with 2.24 getpid() started to become prohibitively expensive when used for detecting when + * objects were used across fork()s. With this caching the old behaviour is somewhat restored. + * + * https://bugzilla.redhat.com/show_bug.cgi?id=1443976 + * https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c579f48edba88380635ab98cb612030e3ed8691e + */ + + current_value = __sync_val_compare_and_swap(&cached_pid, CACHED_PID_UNSET, CACHED_PID_BUSY); + + switch (current_value) { + + case CACHED_PID_UNSET: { /* Not initialized yet, then do so now */ + pid_t new_pid; + + new_pid = raw_getpid(); + + if (!installed) { + /* __register_atfork() either returns 0 or -ENOMEM, in its glibc implementation. Since it's + * only half-documented (glibc doesn't document it but LSB does — though only superficially) + * we'll check for errors only in the most generic fashion possible. */ + + if (__register_atfork(NULL, NULL, reset_cached_pid, __dso_handle) != 0) { + /* OOM? Let's try again later */ + cached_pid = CACHED_PID_UNSET; + return new_pid; + } + + installed = true; + } + + cached_pid = new_pid; + return new_pid; + } + + case CACHED_PID_BUSY: /* Somebody else is currently initializing */ + return raw_getpid(); + + default: /* Properly initialized */ + return current_value; + } +} + +int must_be_root(void) { + + if (geteuid() == 0) + return 0; + + return log_error_errno(SYNTHETIC_ERRNO(EPERM), "Need to be root."); +} + +int safe_fork_full( + const char *name, + const int except_fds[], + size_t n_except_fds, + ForkFlags flags, + pid_t *ret_pid) { + + pid_t original_pid, pid; + sigset_t saved_ss, ss; + bool block_signals = false; + int prio, r; + + /* A wrapper around fork(), that does a couple of important initializations in addition to mere forking. Always + * returns the child's PID in *ret_pid. Returns == 0 in the child, and > 0 in the parent. */ + + prio = flags & FORK_LOG ? LOG_ERR : LOG_DEBUG; + + original_pid = getpid_cached(); + + if (flags & (FORK_RESET_SIGNALS|FORK_DEATHSIG)) { + /* We temporarily block all signals, so that the new child has them blocked initially. This way, we can + * be sure that SIGTERMs are not lost we might send to the child. */ + + assert_se(sigfillset(&ss) >= 0); + block_signals = true; + + } else if (flags & FORK_WAIT) { + /* Let's block SIGCHLD at least, so that we can safely watch for the child process */ + + assert_se(sigemptyset(&ss) >= 0); + assert_se(sigaddset(&ss, SIGCHLD) >= 0); + block_signals = true; + } + + if (block_signals) + if (sigprocmask(SIG_SETMASK, &ss, &saved_ss) < 0) + return log_full_errno(prio, errno, "Failed to set signal mask: %m"); + + if (flags & FORK_NEW_MOUNTNS) + pid = raw_clone(SIGCHLD|CLONE_NEWNS); + else + pid = fork(); + if (pid < 0) { + r = -errno; + + if (block_signals) /* undo what we did above */ + (void) sigprocmask(SIG_SETMASK, &saved_ss, NULL); + + return log_full_errno(prio, r, "Failed to fork: %m"); + } + if (pid > 0) { + /* We are in the parent process */ + + log_debug("Successfully forked off '%s' as PID " PID_FMT ".", strna(name), pid); + + if (flags & FORK_WAIT) { + r = wait_for_terminate_and_check(name, pid, (flags & FORK_LOG ? WAIT_LOG : 0)); + if (r < 0) + return r; + if (r != EXIT_SUCCESS) /* exit status > 0 should be treated as failure, too */ + return -EPROTO; + } + + if (block_signals) /* undo what we did above */ + (void) sigprocmask(SIG_SETMASK, &saved_ss, NULL); + + if (ret_pid) + *ret_pid = pid; + + return 1; + } + + /* We are in the child process */ + + if (flags & FORK_REOPEN_LOG) { + /* Close the logs if requested, before we log anything. And make sure we reopen it if needed. */ + log_close(); + log_set_open_when_needed(true); + } + + if (name) { + r = rename_process(name); + if (r < 0) + log_full_errno(flags & FORK_LOG ? LOG_WARNING : LOG_DEBUG, + r, "Failed to rename process, ignoring: %m"); + } + + if (flags & FORK_DEATHSIG) + if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0) { + log_full_errno(prio, errno, "Failed to set death signal: %m"); + _exit(EXIT_FAILURE); + } + + if (flags & FORK_RESET_SIGNALS) { + r = reset_all_signal_handlers(); + if (r < 0) { + log_full_errno(prio, r, "Failed to reset signal handlers: %m"); + _exit(EXIT_FAILURE); + } + + /* This implicitly undoes the signal mask stuff we did before the fork()ing above */ + r = reset_signal_mask(); + if (r < 0) { + log_full_errno(prio, r, "Failed to reset signal mask: %m"); + _exit(EXIT_FAILURE); + } + } else if (block_signals) { /* undo what we did above */ + if (sigprocmask(SIG_SETMASK, &saved_ss, NULL) < 0) { + log_full_errno(prio, errno, "Failed to restore signal mask: %m"); + _exit(EXIT_FAILURE); + } + } + + if (flags & FORK_DEATHSIG) { + pid_t ppid; + /* Let's see if the parent PID is still the one we started from? If not, then the parent + * already died by the time we set PR_SET_PDEATHSIG, hence let's emulate the effect */ + + ppid = getppid(); + if (ppid == 0) + /* Parent is in a differn't PID namespace. */; + else if (ppid != original_pid) { + log_debug("Parent died early, raising SIGTERM."); + (void) raise(SIGTERM); + _exit(EXIT_FAILURE); + } + } + + if (FLAGS_SET(flags, FORK_NEW_MOUNTNS | FORK_MOUNTNS_SLAVE)) { + + /* Optionally, make sure we never propagate mounts to the host. */ + + if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) < 0) { + log_full_errno(prio, errno, "Failed to remount root directory as MS_SLAVE: %m"); + _exit(EXIT_FAILURE); + } + } + + if (flags & FORK_CLOSE_ALL_FDS) { + /* Close the logs here in case it got reopened above, as close_all_fds() would close them for us */ + log_close(); + + r = close_all_fds(except_fds, n_except_fds); + if (r < 0) { + log_full_errno(prio, r, "Failed to close all file descriptors: %m"); + _exit(EXIT_FAILURE); + } + } + + /* When we were asked to reopen the logs, do so again now */ + if (flags & FORK_REOPEN_LOG) { + log_open(); + log_set_open_when_needed(false); + } + + if (flags & FORK_NULL_STDIO) { + r = make_null_stdio(); + if (r < 0) { + log_full_errno(prio, r, "Failed to connect stdin/stdout to /dev/null: %m"); + _exit(EXIT_FAILURE); + } + } + + if (flags & FORK_RLIMIT_NOFILE_SAFE) { + r = rlimit_nofile_safe(); + if (r < 0) { + log_full_errno(prio, r, "Failed to lower RLIMIT_NOFILE's soft limit to 1K: %m"); + _exit(EXIT_FAILURE); + } + } + + if (ret_pid) + *ret_pid = getpid_cached(); + + return 0; +} + +int namespace_fork( + const char *outer_name, + const char *inner_name, + const int except_fds[], + size_t n_except_fds, + ForkFlags flags, + int pidns_fd, + int mntns_fd, + int netns_fd, + int userns_fd, + int root_fd, + pid_t *ret_pid) { + + int r; + + /* This is much like safe_fork(), but forks twice, and joins the specified namespaces in the middle + * process. This ensures that we are fully a member of the destination namespace, with pidns an all, so that + * /proc/self/fd works correctly. */ + + r = safe_fork_full(outer_name, except_fds, n_except_fds, (flags|FORK_DEATHSIG) & ~(FORK_REOPEN_LOG|FORK_NEW_MOUNTNS|FORK_MOUNTNS_SLAVE), ret_pid); + if (r < 0) + return r; + if (r == 0) { + pid_t pid; + + /* Child */ + + r = namespace_enter(pidns_fd, mntns_fd, netns_fd, userns_fd, root_fd); + if (r < 0) { + log_full_errno(FLAGS_SET(flags, FORK_LOG) ? LOG_ERR : LOG_DEBUG, r, "Failed to join namespace: %m"); + _exit(EXIT_FAILURE); + } + + /* We mask a few flags here that either make no sense for the grandchild, or that we don't have to do again */ + r = safe_fork_full(inner_name, except_fds, n_except_fds, flags & ~(FORK_WAIT|FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_NULL_STDIO), &pid); + if (r < 0) + _exit(EXIT_FAILURE); + if (r == 0) { + /* Child */ + if (ret_pid) + *ret_pid = pid; + return 0; + } + + r = wait_for_terminate_and_check(inner_name, pid, FLAGS_SET(flags, FORK_LOG) ? WAIT_LOG : 0); + if (r < 0) + _exit(EXIT_FAILURE); + + _exit(r); + } + + return 1; +} + +int fork_agent(const char *name, const int except[], size_t n_except, pid_t *ret_pid, const char *path, ...) { + bool stdout_is_tty, stderr_is_tty; + size_t n, i; + va_list ap; + char **l; + int r; + + assert(path); + + /* Spawns a temporary TTY agent, making sure it goes away when we go away */ + + r = safe_fork_full(name, except, n_except, FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_CLOSE_ALL_FDS, ret_pid); + if (r < 0) + return r; + if (r > 0) + return 0; + + /* In the child: */ + + stdout_is_tty = isatty(STDOUT_FILENO); + stderr_is_tty = isatty(STDERR_FILENO); + + if (!stdout_is_tty || !stderr_is_tty) { + int fd; + + /* Detach from stdout/stderr. and reopen + * /dev/tty for them. This is important to + * ensure that when systemctl is started via + * popen() or a similar call that expects to + * read EOF we actually do generate EOF and + * not delay this indefinitely by because we + * keep an unused copy of stdin around. */ + fd = open("/dev/tty", O_WRONLY); + if (fd < 0) { + log_error_errno(errno, "Failed to open /dev/tty: %m"); + _exit(EXIT_FAILURE); + } + + if (!stdout_is_tty && dup2(fd, STDOUT_FILENO) < 0) { + log_error_errno(errno, "Failed to dup2 /dev/tty: %m"); + _exit(EXIT_FAILURE); + } + + if (!stderr_is_tty && dup2(fd, STDERR_FILENO) < 0) { + log_error_errno(errno, "Failed to dup2 /dev/tty: %m"); + _exit(EXIT_FAILURE); + } + + safe_close_above_stdio(fd); + } + + (void) rlimit_nofile_safe(); + + /* Count arguments */ + va_start(ap, path); + for (n = 0; va_arg(ap, char*); n++) + ; + va_end(ap); + + /* Allocate strv */ + l = newa(char*, n + 1); + + /* Fill in arguments */ + va_start(ap, path); + for (i = 0; i <= n; i++) + l[i] = va_arg(ap, char*); + va_end(ap); + + execv(path, l); + _exit(EXIT_FAILURE); +} + +int set_oom_score_adjust(int value) { + char t[DECIMAL_STR_MAX(int)]; + + sprintf(t, "%i", value); + + return write_string_file("/proc/self/oom_score_adj", t, + WRITE_STRING_FILE_VERIFY_ON_FAILURE|WRITE_STRING_FILE_DISABLE_BUFFER); +} + +static const char *const ioprio_class_table[] = { + [IOPRIO_CLASS_NONE] = "none", + [IOPRIO_CLASS_RT] = "realtime", + [IOPRIO_CLASS_BE] = "best-effort", + [IOPRIO_CLASS_IDLE] = "idle" +}; + +DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(ioprio_class, int, IOPRIO_N_CLASSES); + +static const char *const sigchld_code_table[] = { + [CLD_EXITED] = "exited", + [CLD_KILLED] = "killed", + [CLD_DUMPED] = "dumped", + [CLD_TRAPPED] = "trapped", + [CLD_STOPPED] = "stopped", + [CLD_CONTINUED] = "continued", +}; + +DEFINE_STRING_TABLE_LOOKUP(sigchld_code, int); + +static const char* const sched_policy_table[] = { + [SCHED_OTHER] = "other", + [SCHED_BATCH] = "batch", + [SCHED_IDLE] = "idle", + [SCHED_FIFO] = "fifo", + [SCHED_RR] = "rr" +}; + +DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(sched_policy, int, INT_MAX); |