diff options
Diffstat (limited to 'daemon/daemon.c')
| -rw-r--r-- | daemon/daemon.c | 452 |
1 files changed, 452 insertions, 0 deletions
diff --git a/daemon/daemon.c b/daemon/daemon.c new file mode 100644 index 000000000..4ad082b95 --- /dev/null +++ b/daemon/daemon.c @@ -0,0 +1,452 @@ +// SPDX-License-Identifier: GPL-3.0-or-later + +#include "common.h" +#include <sched.h> + +char pidfile[FILENAME_MAX + 1] = ""; + +static void chown_open_file(int fd, uid_t uid, gid_t gid) { + if(fd == -1) return; + + struct stat buf; + + if(fstat(fd, &buf) == -1) { + error("Cannot fstat() fd %d", fd); + return; + } + + if((buf.st_uid != uid || buf.st_gid != gid) && S_ISREG(buf.st_mode)) { + if(fchown(fd, uid, gid) == -1) + error("Cannot fchown() fd %d.", fd); + } +} + +void create_needed_dir(const char *dir, uid_t uid, gid_t gid) +{ + // attempt to create the directory + if(mkdir(dir, 0755) == 0) { + // we created it + + // chown it to match the required user + if(chown(dir, uid, gid) == -1) + error("Cannot chown directory '%s' to %u:%u", dir, (unsigned int)uid, (unsigned int)gid); + } + else if(errno != EEXIST) + // log an error only if the directory does not exist + error("Cannot create directory '%s'", dir); +} + +int become_user(const char *username, int pid_fd) { + int am_i_root = (getuid() == 0)?1:0; + + struct passwd *pw = getpwnam(username); + if(!pw) { + error("User %s is not present.", username); + return -1; + } + + uid_t uid = pw->pw_uid; + gid_t gid = pw->pw_gid; + + create_needed_dir(netdata_configured_cache_dir, uid, gid); + create_needed_dir(netdata_configured_varlib_dir, uid, gid); + + if(pidfile[0]) { + if(chown(pidfile, uid, gid) == -1) + error("Cannot chown '%s' to %u:%u", pidfile, (unsigned int)uid, (unsigned int)gid); + } + + int ngroups = (int)sysconf(_SC_NGROUPS_MAX); + gid_t *supplementary_groups = NULL; + if(ngroups > 0) { + supplementary_groups = mallocz(sizeof(gid_t) * ngroups); + if(getgrouplist(username, gid, supplementary_groups, &ngroups) == -1) { + if(am_i_root) + error("Cannot get supplementary groups of user '%s'.", username); + + ngroups = 0; + } + } + + chown_open_file(STDOUT_FILENO, uid, gid); + chown_open_file(STDERR_FILENO, uid, gid); + chown_open_file(stdaccess_fd, uid, gid); + chown_open_file(pid_fd, uid, gid); + + if(supplementary_groups && ngroups > 0) { + if(setgroups((size_t)ngroups, supplementary_groups) == -1) { + if(am_i_root) + error("Cannot set supplementary groups for user '%s'", username); + } + ngroups = 0; + } + + if(supplementary_groups) + freez(supplementary_groups); + +#ifdef __APPLE__ + if(setregid(gid, gid) != 0) { +#else + if(setresgid(gid, gid, gid) != 0) { +#endif /* __APPLE__ */ + error("Cannot switch to user's %s group (gid: %u).", username, gid); + return -1; + } + +#ifdef __APPLE__ + if(setreuid(uid, uid) != 0) { +#else + if(setresuid(uid, uid, uid) != 0) { +#endif /* __APPLE__ */ + error("Cannot switch to user %s (uid: %u).", username, uid); + return -1; + } + + if(setgid(gid) != 0) { + error("Cannot switch to user's %s group (gid: %u).", username, gid); + return -1; + } + if(setegid(gid) != 0) { + error("Cannot effectively switch to user's %s group (gid: %u).", username, gid); + return -1; + } + if(setuid(uid) != 0) { + error("Cannot switch to user %s (uid: %u).", username, uid); + return -1; + } + if(seteuid(uid) != 0) { + error("Cannot effectively switch to user %s (uid: %u).", username, uid); + return -1; + } + + return(0); +} + +#ifndef OOM_SCORE_ADJ_MAX +#define OOM_SCORE_ADJ_MAX (1000) +#endif +#ifndef OOM_SCORE_ADJ_MIN +#define OOM_SCORE_ADJ_MIN (-1000) +#endif + +static void oom_score_adj(void) { + char buf[30 + 1]; + long long int old_score, wanted_score = OOM_SCORE_ADJ_MAX, final_score = 0; + + // read the existing score + if(read_single_signed_number_file("/proc/self/oom_score_adj", &old_score)) { + error("Out-Of-Memory (OOM) score setting is not supported on this system."); + return; + } + + if(old_score != 0) + wanted_score = old_score; + + // check the environment + char *s = getenv("OOMScoreAdjust"); + if(!s || !*s) { + snprintfz(buf, 30, "%d", (int)wanted_score); + s = buf; + } + + // check netdata.conf configuration + s = config_get(CONFIG_SECTION_GLOBAL, "OOM score", s); + if(s && *s && (isdigit(*s) || *s == '-' || *s == '+')) + wanted_score = atoll(s); + else if(s && !strcmp(s, "keep")) { + info("Out-Of-Memory (OOM) kept as-is (running with %d)", (int) old_score); + return; + } + else { + info("Out-Of-Memory (OOM) score not changed due to non-numeric setting: '%s' (running with %d)", s, (int)old_score); + return; + } + + if(wanted_score < OOM_SCORE_ADJ_MIN) { + error("Wanted Out-Of-Memory (OOM) score %d is too small. Using %d", (int)wanted_score, (int)OOM_SCORE_ADJ_MIN); + wanted_score = OOM_SCORE_ADJ_MIN; + } + + if(wanted_score > OOM_SCORE_ADJ_MAX) { + error("Wanted Out-Of-Memory (OOM) score %d is too big. Using %d", (int)wanted_score, (int)OOM_SCORE_ADJ_MAX); + wanted_score = OOM_SCORE_ADJ_MAX; + } + + if(old_score == wanted_score) { + info("Out-Of-Memory (OOM) score is already set to the wanted value %d", (int)old_score); + return; + } + + int written = 0; + int fd = open("/proc/self/oom_score_adj", O_WRONLY); + if(fd != -1) { + snprintfz(buf, 30, "%d", (int)wanted_score); + ssize_t len = strlen(buf); + if(len > 0 && write(fd, buf, (size_t)len) == len) written = 1; + close(fd); + + if(written) { + if(read_single_signed_number_file("/proc/self/oom_score_adj", &final_score)) + error("Adjusted my Out-Of-Memory (OOM) score to %d, but cannot verify it.", (int)wanted_score); + else if(final_score == wanted_score) + info("Adjusted my Out-Of-Memory (OOM) score from %d to %d.", (int)old_score, (int)final_score); + else + error("Adjusted my Out-Of-Memory (OOM) score from %d to %d, but it has been set to %d.", (int)old_score, (int)wanted_score, (int)final_score); + } + else + error("Failed to adjust my Out-Of-Memory (OOM) score to %d. Running with %d. (systemd systems may change it via netdata.service)", (int)wanted_score, (int)old_score); + } + else + error("Failed to adjust my Out-Of-Memory (OOM) score. Cannot open /proc/self/oom_score_adj for writing."); +} + +static void process_nice_level(void) { +#ifdef HAVE_NICE + int nice_level = (int)config_get_number(CONFIG_SECTION_GLOBAL, "process nice level", 19); + if(nice(nice_level) == -1) error("Cannot set netdata CPU nice level to %d.", nice_level); + else debug(D_SYSTEM, "Set netdata nice level to %d.", nice_level); +#endif // HAVE_NICE +}; + +#define SCHED_FLAG_NONE 0x00 +#define SCHED_FLAG_PRIORITY_CONFIGURABLE 0x01 // the priority is user configurable +#define SCHED_FLAG_KEEP_AS_IS 0x04 // do not attempt to set policy, priority or nice() +#define SCHED_FLAG_USE_NICE 0x08 // use nice() after setting this policy + +struct sched_def { + char *name; + int policy; + int priority; + uint8_t flags; +} scheduler_defaults[] = { + + // the order of array members is important! + // the first defined is the default used by netdata + + // the available members are important too! + // these are all the possible scheduling policies supported by netdata + +#ifdef SCHED_IDLE + { "idle", SCHED_IDLE, 0, SCHED_FLAG_NONE }, +#endif + +#ifdef SCHED_OTHER + { "other", SCHED_OTHER, 0, SCHED_FLAG_USE_NICE }, + { "nice", SCHED_OTHER, 0, SCHED_FLAG_USE_NICE }, +#endif + +#ifdef SCHED_RR + { "rr", SCHED_RR, 0, SCHED_FLAG_PRIORITY_CONFIGURABLE }, +#endif + +#ifdef SCHED_FIFO + { "fifo", SCHED_FIFO, 0, SCHED_FLAG_PRIORITY_CONFIGURABLE }, +#endif + +#ifdef SCHED_BATCH + { "batch", SCHED_BATCH, 0, SCHED_FLAG_USE_NICE }, +#endif + + // do not change the scheduling priority + { "keep", 0, 0, SCHED_FLAG_KEEP_AS_IS }, + { "none", 0, 0, SCHED_FLAG_KEEP_AS_IS }, + + // array termination + { NULL, 0, 0, 0 } +}; + + +#ifdef HAVE_SCHED_GETSCHEDULER +static void sched_getscheduler_report(void) { + int sched = sched_getscheduler(0); + if(sched == -1) { + error("Cannot get my current process scheduling policy."); + return; + } + else { + int i; + for(i = 0 ; scheduler_defaults[i].name ; i++) { + if(scheduler_defaults[i].policy == sched) { + if(scheduler_defaults[i].flags & SCHED_FLAG_PRIORITY_CONFIGURABLE) { + struct sched_param param; + if(sched_getparam(0, ¶m) == -1) { + error("Cannot get the process scheduling priority for my policy '%s'", scheduler_defaults[i].name); + return; + } + else { + info("Running with process scheduling policy '%s', priority %d", scheduler_defaults[i].name, param.sched_priority); + } + } + else if(scheduler_defaults[i].flags & SCHED_FLAG_USE_NICE) { + #ifdef HAVE_GETPRIORITY + int n = getpriority(PRIO_PROCESS, 0); + info("Running with process scheduling policy '%s', nice level %d", scheduler_defaults[i].name, n); + #else // !HAVE_GETPRIORITY + info("Running with process scheduling policy '%s'", scheduler_defaults[i].name); + #endif // !HAVE_GETPRIORITY + } + else { + info("Running with process scheduling policy '%s'", scheduler_defaults[i].name); + } + + return; + } + } + } +} +#else // !HAVE_SCHED_GETSCHEDULER +static void sched_getscheduler_report(void) { +#ifdef HAVE_GETPRIORITY + info("Running with priority %d", getpriority(PRIO_PROCESS, 0)); +#endif // HAVE_GETPRIORITY +} +#endif // !HAVE_SCHED_GETSCHEDULER + +#ifdef HAVE_SCHED_SETSCHEDULER + +static void sched_setscheduler_set(void) { + + if(scheduler_defaults[0].name) { + const char *name = scheduler_defaults[0].name; + int policy = scheduler_defaults[0].policy, priority = scheduler_defaults[0].priority; + uint8_t flags = scheduler_defaults[0].flags; + int found = 0; + + // read the configuration + name = config_get(CONFIG_SECTION_GLOBAL, "process scheduling policy", name); + int i; + for(i = 0 ; scheduler_defaults[i].name ; i++) { + if(!strcmp(name, scheduler_defaults[i].name)) { + found = 1; + policy = scheduler_defaults[i].policy; + priority = scheduler_defaults[i].priority; + flags = scheduler_defaults[i].flags; + + if(flags & SCHED_FLAG_KEEP_AS_IS) + goto report; + + if(flags & SCHED_FLAG_PRIORITY_CONFIGURABLE) + priority = (int)config_get_number(CONFIG_SECTION_GLOBAL, "process scheduling priority", priority); + +#ifdef HAVE_SCHED_GET_PRIORITY_MIN + errno = 0; + if(priority < sched_get_priority_min(policy)) { + error("scheduler %s (%d) priority %d is below the minimum %d. Using the minimum.", name, policy, priority, sched_get_priority_min(policy)); + priority = sched_get_priority_min(policy); + } +#endif +#ifdef HAVE_SCHED_GET_PRIORITY_MAX + errno = 0; + if(priority > sched_get_priority_max(policy)) { + error("scheduler %s (%d) priority %d is above the maximum %d. Using the maximum.", name, policy, priority, sched_get_priority_max(policy)); + priority = sched_get_priority_max(policy); + } +#endif + break; + } + } + + if(!found) { + error("Unknown scheduling policy '%s' - falling back to nice", name); + goto fallback; + } + + const struct sched_param param = { + .sched_priority = priority + }; + + errno = 0; + i = sched_setscheduler(0, policy, ¶m); + if(i != 0) { + error("Cannot adjust netdata scheduling policy to %s (%d), with priority %d. Falling back to nice.", name, policy, priority); + } + else { + info("Adjusted netdata scheduling policy to %s (%d), with priority %d.", name, policy, priority); + if(!(flags & SCHED_FLAG_USE_NICE)) + goto report; + } + } + +fallback: + process_nice_level(); + +report: + sched_getscheduler_report(); +} +#else // !HAVE_SCHED_SETSCHEDULER +static void sched_setscheduler_set(void) { + process_nice_level(); +} +#endif // !HAVE_SCHED_SETSCHEDULER + +int become_daemon(int dont_fork, const char *user) +{ + if(!dont_fork) { + int i = fork(); + if(i == -1) { + perror("cannot fork"); + exit(1); + } + if(i != 0) { + exit(0); // the parent + } + + // become session leader + if (setsid() < 0) { + perror("Cannot become session leader."); + exit(2); + } + + // fork() again + i = fork(); + if(i == -1) { + perror("cannot fork"); + exit(1); + } + if(i != 0) { + exit(0); // the parent + } + } + + // generate our pid file + int pidfd = -1; + if(pidfile[0]) { + pidfd = open(pidfile, O_WRONLY | O_CREAT, 0644); + if(pidfd >= 0) { + if(ftruncate(pidfd, 0) != 0) + error("Cannot truncate pidfile '%s'.", pidfile); + + char b[100]; + sprintf(b, "%d\n", getpid()); + ssize_t i = write(pidfd, b, strlen(b)); + if(i <= 0) + error("Cannot write pidfile '%s'.", pidfile); + } + else error("Failed to open pidfile '%s'.", pidfile); + } + + // Set new file permissions + umask(0007); + + // adjust my Out-Of-Memory score + oom_score_adj(); + + // never become a problem + sched_setscheduler_set(); + + if(user && *user) { + if(become_user(user, pidfd) != 0) { + error("Cannot become user '%s'. Continuing as we are.", user); + } + else debug(D_SYSTEM, "Successfully became user '%s'.", user); + } + else { + create_needed_dir(netdata_configured_cache_dir, getuid(), getgid()); + create_needed_dir(netdata_configured_varlib_dir, getuid(), getgid()); + } + + if(pidfd != -1) + close(pidfd); + + return(0); +} |