summaryrefslogtreecommitdiffstats
path: root/src/basic/process-util.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--src/basic/process-util.c1565
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);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 23:40:19 +0000