+/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
#include <sys/wait.h>
#include <syslog.h>
#include <unistd.h>
-#ifdef HAVE_VALGRIND_VALGRIND_H
+#if HAVE_VALGRIND_VALGRIND_H
#include <valgrind/valgrind.h>
#endif
/* 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. */
- if (mm_size < l+1) {
+
+ /* 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;
- /* Let's not bother with this if we don't have euid == 0. Strictly speaking if people do weird stuff
- * with capabilities this could work even for euid != 0, but our own code generally doesn't do that,
- * hence let's use this as quick bypass check, to avoid calling mmap() if PR_SET_MM_ARG_START 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_ARG_START, as we don't have privileges.");
- goto use_saved_argv;
- }
-
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) {
mm = nn;
mm_size = nn_size;
- } else
+ } 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 */
bool eof;
FILE *f;
- if (pid == 0 || pid == 1) /* pid 1, and we ourselves certainly aren't a kernel thread */
+ if (IN_SET(pid, 0, 1) || pid == getpid_cached()) /* pid 1, and we ourselves certainly aren't a kernel thread */
return 0;
assert(pid > 1);
assert(field);
assert(uid);
+ if (pid < 0)
+ return -EINVAL;
+
p = procfs_file_alloca(pid, "status");
f = fopen(p, "re");
if (!f) {
}
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);
}
assert(pid >= 0);
assert(_ppid);
- if (pid == 0) {
+ if (pid == 0 || pid == getpid_cached()) {
*_ppid = getppid();
return 0;
}
log_debug("%s succeeded.", name);
return status.si_status;
- } else if (status.si_code == CLD_KILLED ||
- status.si_code == CLD_DUMPED) {
+ } else if (IN_SET(status.si_code, CLD_KILLED, CLD_DUMPED)) {
log_warning("%s terminated by signal %s.", name, signal_to_string(status.si_status));
return -EPROTO;
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;
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 (r == -ESRCH || r == 'Z')
+ if (IN_SET(r, -ESRCH, 'Z'))
return false;
return true;
const char *root;
if (pid < 0)
- return 0;
+ return false;
+
+ if (pid == 0 || pid == getpid_cached())
+ return true;
root = procfs_file_alloca(pid, "root");
- return files_same(root, "/proc/1/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() == gettid() ? 1 : -1;
+ cached = getpid_cached() == gettid() ? 1 : -1;
return cached > 0;
}
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) {
-#ifdef HAVE_VALGRIND_VALGRIND_H
- if (getpid() == 1 && RUNNING_ON_VALGRIND) {
+#if HAVE_VALGRIND_VALGRIND_H
+ if (getpid_cached() == 1 && RUNNING_ON_VALGRIND) {
pid_t pid;
pid = raw_clone(SIGCHLD);
if (pid < 0)
return 0;
}
+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;
+
+static 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 __attribute__ ((__weak__));
+
+pid_t getpid_cached(void) {
+ 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 = getpid();
+
+ 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;
+ }
+
+ cached_pid = new_pid;
+ return new_pid;
+ }
+
+ case CACHED_PID_BUSY: /* Somebody else is currently initializing */
+ return getpid();
+
+ default: /* Properly initialized */
+ return current_value;
+ }
+}
+
static const char *const ioprio_class_table[] = {
[IOPRIO_CLASS_NONE] = "none",
[IOPRIO_CLASS_RT] = "realtime",
projects / thirdparty / systemd.git / blobdiff