Re: [libvirt] [PATCH v2] virtlockd: make re-exec more robust

- Use $XDG_RUNTIME_DIR for re-exec state file when running unprivileged. - argv[0] may not contain a full path to the binary, however it should contain something that can be looked up in the PATH. Use execvp() to do path lookup on re-exec. - As per list discussion [1], ignore --daemon on re-exec. [1] https://www.redhat.com/archives/libvir-list/2013-December/msg00514.html Signed-off-by: Michael Chapman <mike(a)very.puzzling.org&gt; --- src/locking/lock_daemon.c | 128 ++++++++++++++++++++++++++++++++++------------ 1 file changed, 94 insertions(+), 34 deletions(-) diff --git a/src/locking/lock_daemon.c b/src/locking/lock_daemon.c index a6be43c..b405e3a 100644 --- a/src/locking/lock_daemon.c +++ b/src/locking/lock_daemon.c @@ -925,7 +925,41 @@ error: } -#define VIR_LOCK_DAEMON_RESTART_EXEC_FILE LOCALSTATEDIR "/run/virtlockd-restart-exec.json" +static int +virLockDaemonExecRestartStatePath(bool privileged, + char **state_file) +{ + if (privileged) { + if (VIR_STRDUP(*state_file, LOCALSTATEDIR "/run/virtlockd-restart-exec.json") < 0) + goto error; + } else { + char *rundir = NULL; + mode_t old_umask; + + if (!(rundir = virGetUserRuntimeDirectory())) + goto error; + + old_umask = umask(077); + if (virFileMakePath(rundir) < 0) { + umask(old_umask); + goto error;

+ } + umask(old_umask); + + if (virAsprintf(state_file, "%s/virtlockd-restart-exec.json", rundir) < 0) { + VIR_FREE(rundir); + goto error; + } + + VIR_FREE(rundir); + } + + return 0; + +error:

+ return -1; +} + static char * virLockDaemonGetExecRestartMagic(void) @@ -938,7 +972,10 @@ virLockDaemonGetExecRestartMagic(void) static int -virLockDaemonPostExecRestart(bool privileged) +virLockDaemonPostExecRestart(const char *state_file, + const char *pid_file, + int *pid_file_fd, + bool privileged) { const char *gotmagic; char *wantmagic = NULL; @@ -948,14 +985,14 @@ virLockDaemonPostExecRestart(bool privileged) VIR_DEBUG("Running post-restart exec"); - if (!virFileExists(VIR_LOCK_DAEMON_RESTART_EXEC_FILE)) { - VIR_DEBUG("No restart file %s present", - VIR_LOCK_DAEMON_RESTART_EXEC_FILE); + if (!virFileExists(state_file)) { + VIR_DEBUG("No restart state file %s present", + state_file); ret = 0; goto cleanup; } - if (virFileReadAll(VIR_LOCK_DAEMON_RESTART_EXEC_FILE, + if (virFileReadAll(state_file, 1024 * 1024 * 10, /* 10 MB */ &state) < 0) goto cleanup; @@ -982,13 +1019,18 @@ virLockDaemonPostExecRestart(bool privileged) goto cleanup; } + /* Re-claim PID file now as we will not be daemonizing */ + if (pid_file && + (*pid_file_fd = virPidFileAcquirePath(pid_file, getpid())) < 0) + goto cleanup; + if (!(lockDaemon = virLockDaemonNewPostExecRestart(object, privileged))) goto cleanup; ret = 1; cleanup: - unlink(VIR_LOCK_DAEMON_RESTART_EXEC_FILE); + unlink(state_file); VIR_FREE(wantmagic); VIR_FREE(state); virJSONValueFree(object); @@ -997,7 +1039,8 @@ cleanup: static int -virLockDaemonPreExecRestart(virNetServerPtr srv, +virLockDaemonPreExecRestart(const char *state_file, + virNetServerPtr srv, char **argv) { virJSONValuePtr child; @@ -1065,15 +1108,15 @@ virLockDaemonPreExecRestart(virNetServerPtr srv, VIR_DEBUG("Saving state %s", state); - if (virFileWriteStr(VIR_LOCK_DAEMON_RESTART_EXEC_FILE, + if (virFileWriteStr(state_file, state, 0700) < 0) { virReportSystemError(errno, _("Unable to save state file %s"), - VIR_LOCK_DAEMON_RESTART_EXEC_FILE); + state_file); goto cleanup; } - if (execv(argv[0], argv) < 0) { + if (execvp(argv[0], argv) < 0) { virReportSystemError(errno, "%s", _("Unable to restart self")); goto cleanup; @@ -1153,6 +1196,7 @@ int main(int argc, char **argv) { char *pid_file = NULL; int pid_file_fd = -1; char *sock_file = NULL; + char *state_file = NULL; bool implicit_conf = false; mode_t old_umask; bool privileged = false; @@ -1276,21 +1320,13 @@ int main(int argc, char **argv) { VIR_DEBUG("Decided on socket paths '%s'", sock_file); - if (godaemon) { - char ebuf[1024]; - - if (chdir("/") < 0) { - VIR_ERROR(_("cannot change to root directory: %s"), - virStrerror(errno, ebuf, sizeof(ebuf))); - goto cleanup; - } - - if ((statuswrite = virLockDaemonForkIntoBackground(argv[0])) < 0) { - VIR_ERROR(_("Failed to fork as daemon: %s"), - virStrerror(errno, ebuf, sizeof(ebuf))); - goto cleanup; - } + if (virLockDaemonExecRestartStatePath(privileged, + &state_file) < 0) { + VIR_ERROR(_("Can't determine restart state file path")); + exit(EXIT_FAILURE); } + VIR_DEBUG("Decided on restart state file path '%s'", + state_file); /* Ensure the rundir exists (on tmpfs on some systems) */ if (privileged) { @@ -1317,20 +1353,41 @@ int main(int argc, char **argv) { } umask(old_umask); - /* If we have a pidfile set, claim it now, exiting if already taken */ - if ((pid_file_fd = virPidFileAcquirePath(pid_file, getpid())) < 0) { - ret = VIR_LOCK_DAEMON_ERR_PIDFILE; - goto cleanup; - } - - if ((rv = virLockDaemonPostExecRestart(privileged)) < 0) { + if ((rv = virLockDaemonPostExecRestart(state_file, + pid_file, + &pid_file_fd, + privileged)) < 0) { ret = VIR_LOCK_DAEMON_ERR_INIT; goto cleanup; } /* rv == 1, means we setup everything from saved state, - * so we only setup stuff from scratch if rv == 0 */ + * so only (possibly) daemonize and setup stuff from + * scratch if rv == 0 + */ if (rv == 0) { + if (godaemon) { + char ebuf[1024]; + + if (chdir("/") < 0) { + VIR_ERROR(_("cannot change to root directory: %s"), + virStrerror(errno, ebuf, sizeof(ebuf))); + goto cleanup; + } + + if ((statuswrite = virLockDaemonForkIntoBackground(argv[0])) < 0) { + VIR_ERROR(_("Failed to fork as daemon: %s"), + virStrerror(errno, ebuf, sizeof(ebuf))); + goto cleanup; + } + } + + /* If we have a pidfile set, claim it now, exiting if already taken */ + if ((pid_file_fd = virPidFileAcquirePath(pid_file, getpid())) < 0) { + ret = VIR_LOCK_DAEMON_ERR_PIDFILE; + goto cleanup; + } + if (!(lockDaemon = virLockDaemonNew(config, privileged))) { ret = VIR_LOCK_DAEMON_ERR_INIT; goto cleanup; @@ -1388,7 +1445,9 @@ int main(int argc, char **argv) { virNetServerRun(lockDaemon->srv); if (execRestart && - virLockDaemonPreExecRestart(lockDaemon->srv, argv) < 0) + virLockDaemonPreExecRestart(state_file, + lockDaemon->srv, + argv) < 0) ret = VIR_LOCK_DAEMON_ERR_REEXEC; else ret = 0; @@ -1410,6 +1469,7 @@ cleanup: virPidFileReleasePath(pid_file, pid_file_fd); VIR_FREE(pid_file); VIR_FREE(sock_file); + VIR_FREE(state_file); VIR_FREE(run_dir); return ret;