/* * udevd.c - hotplug event serializer * * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org> * Copyright (C) 2004 Chris Friesen <chris_friesen@sympatico.ca> * * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation version 2 of the License. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 675 Mass Ave, Cambridge, MA 02139, USA. * */ #include <stddef.h> #include <sys/wait.h> #include <signal.h> #include <unistd.h> #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/time.h> #include <sys/types.h> #include <sys/socket.h> #include <sys/un.h> #include <fcntl.h> #include <sys/sysinfo.h> #include <sys/stat.h> #include "list.h" #include "udev.h" #include "udev_version.h" #include "udev_utils.h" #include "udevd.h" #include "logging.h" /* global variables*/ static int udevsendsock; static int pipefds[2]; static unsigned long long expected_seqnum = 0; static volatile int sigchilds_waiting; static volatile int run_msg_q; static volatile int sig_flag; static int run_exec_q; static LIST_HEAD(msg_list); static LIST_HEAD(exec_list); static LIST_HEAD(running_list); static void exec_queue_manager(void); static void msg_queue_manager(void); static void user_sighandler(void); static void reap_sigchilds(void); char *udev_bin; #ifdef LOG unsigned char logname[LOGNAME_SIZE]; void log_message (int level, const char *format, ...) { va_list args; va_start(args, format); vsyslog(level, format, args); va_end(args); } #endif #define msg_dump(msg) \ dbg("msg_dump: sequence %llu, '%s', '%s', '%s'", \ msg->seqnum, msg->action, msg->devpath, msg->subsystem); static void msg_dump_queue(void) { #ifdef DEBUG struct hotplug_msg *msg; list_for_each_entry(msg, &msg_list, list) dbg("sequence %llu in queue", msg->seqnum); #endif } static void run_queue_delete(struct hotplug_msg *msg) { list_del(&msg->list); free(msg); } /* orders the message in the queue by sequence number */ static void msg_queue_insert(struct hotplug_msg *msg) { struct hotplug_msg *loop_msg; struct sysinfo info; /* sort message by sequence number into list. events * will tend to come in order, so scan the list backwards */ list_for_each_entry_reverse(loop_msg, &msg_list, list) if (loop_msg->seqnum < msg->seqnum) break; /* store timestamp of queuing */ sysinfo(&info); msg->queue_time = info.uptime; list_add(&msg->list, &loop_msg->list); dbg("queued message seq %llu", msg->seqnum); /* run msg queue manager */ run_msg_q = 1; return ; } /* forks event and removes event from run queue when finished */ static void udev_run(struct hotplug_msg *msg) { char *const argv[] = { "udev", msg->subsystem, NULL }; pid_t pid; pid = fork(); switch (pid) { case 0: /* child */ close(udevsendsock); logging_close(); execve(udev_bin, argv, msg->envp); dbg("exec of child failed"); _exit(1); break; case -1: dbg("fork of child failed"); run_queue_delete(msg); /* note: we never managed to run, so we had no impact on * running_with_devpath(), so don't bother setting run_exec_q */ break; default: /* get SIGCHLD in main loop */ dbg("==> exec seq %llu [%d] working at '%s'", msg->seqnum, pid, msg->devpath); msg->pid = pid; } } /* returns already running task with devpath */ static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg) { struct hotplug_msg *loop_msg; list_for_each_entry(loop_msg, &running_list, list) { if (loop_msg->devpath == NULL || msg->devpath == NULL) continue; if (strcmp(loop_msg->devpath, msg->devpath) == 0) return loop_msg; } return NULL; } /* exec queue management routine executes the events and delays events for the same devpath */ static void exec_queue_manager(void) { struct hotplug_msg *loop_msg; struct hotplug_msg *tmp_msg; struct hotplug_msg *msg; list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) { msg = running_with_devpath(loop_msg); if (!msg) { /* move event to run list */ list_move_tail(&loop_msg->list, &running_list); udev_run(loop_msg); dbg("moved seq %llu to running list", loop_msg->seqnum); } else { dbg("delay seq %llu, cause seq %llu already working on '%s'", loop_msg->seqnum, msg->seqnum, msg->devpath); } } } static void msg_move_exec(struct hotplug_msg *msg) { list_move_tail(&msg->list, &exec_list); run_exec_q = 1; expected_seqnum = msg->seqnum+1; dbg("moved seq %llu to exec, next expected is %llu", msg->seqnum, expected_seqnum); } /* msg queue management routine handles the timeouts and dispatches the events */ static void msg_queue_manager(void) { struct hotplug_msg *loop_msg; struct hotplug_msg *tmp_msg; struct sysinfo info; long msg_age = 0; dbg("msg queue manager, next expected is %llu", expected_seqnum); recheck: list_for_each_entry_safe(loop_msg, tmp_msg, &msg_list, list) { /* move event with expected sequence to the exec list */ if (loop_msg->seqnum == expected_seqnum) { msg_move_exec(loop_msg); continue; } /* move event with expired timeout to the exec list */ sysinfo(&info); msg_age = info.uptime - loop_msg->queue_time; dbg("seq %llu is %li seconds old", loop_msg->seqnum, msg_age); if (msg_age > EVENT_TIMEOUT_SEC-1) { msg_move_exec(loop_msg); goto recheck; } else { break; } } msg_dump_queue(); /* set timeout for remaining queued events */ if (list_empty(&msg_list) == 0) { struct itimerval itv = {{0, 0}, {EVENT_TIMEOUT_SEC - msg_age, 0}}; dbg("next event expires in %li seconds", EVENT_TIMEOUT_SEC - msg_age); setitimer(ITIMER_REAL, &itv, NULL); } } /* receive the msg, do some basic sanity checks, and queue it */ static void handle_udevsend_msg(int sock) { static struct udevsend_msg usend_msg; struct hotplug_msg *msg; int bufpos; int i; ssize_t size; struct msghdr smsg; struct cmsghdr *cmsg; struct iovec iov; struct ucred *cred; char cred_msg[CMSG_SPACE(sizeof(struct ucred))]; int envbuf_size; memset(&usend_msg, 0x00, sizeof(struct udevsend_msg)); iov.iov_base = &usend_msg; iov.iov_len = sizeof(struct udevsend_msg); memset(&smsg, 0x00, sizeof(struct msghdr)); smsg.msg_iov = &iov; smsg.msg_iovlen = 1; smsg.msg_control = cred_msg; smsg.msg_controllen = sizeof(cred_msg); size = recvmsg(sock, &smsg, 0); if (size < 0) { if (errno != EINTR) dbg("unable to receive message"); return; } cmsg = CMSG_FIRSTHDR(&smsg); cred = (struct ucred *) CMSG_DATA(cmsg); if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) { dbg("no sender credentials received, message ignored"); goto exit; } if (cred->uid != 0) { dbg("sender uid=%i, message ignored", cred->uid); goto exit; } if (strncmp(usend_msg.magic, UDEV_MAGIC, sizeof(UDEV_MAGIC)) != 0 ) { dbg("message magic '%s' doesn't match, ignore it", usend_msg.magic); goto exit; } envbuf_size = size - offsetof(struct udevsend_msg, envbuf); dbg("envbuf_size=%i", envbuf_size); msg = malloc(sizeof(struct hotplug_msg) + envbuf_size); memset(msg, 0x00, sizeof(struct hotplug_msg) + envbuf_size); /* copy environment buffer and reconstruct envp */ memcpy(msg->envbuf, usend_msg.envbuf, envbuf_size); bufpos = 0; for (i = 0; (bufpos < envbuf_size) && (i < HOTPLUG_NUM_ENVP-2); i++) { int keylen; char *key; key = &msg->envbuf[bufpos]; keylen = strlen(key); msg->envp[i] = key; bufpos += keylen + 1; dbg("add '%s' to msg.envp[%i]", msg->envp[i], i); /* remember some keys for further processing */ if (strncmp(key, "ACTION=", 7) == 0) msg->action = &key[7]; if (strncmp(key, "DEVPATH=", 8) == 0) msg->devpath = &key[8]; if (strncmp(key, "SUBSYSTEM=", 10) == 0) msg->subsystem = &key[10]; if (strncmp(key, "SEQNUM=", 7) == 0) msg->seqnum = strtoull(&key[7], NULL, 10); } msg->envp[i++] = "MANAGED_EVENT=1"; msg->envp[i] = NULL; /* if no seqnum is given, we move straight to exec queue */ if (msg->seqnum == 0) { list_add(&msg->list, &exec_list); run_exec_q = 1; } else { msg_queue_insert(msg); } exit: return; } static void asmlinkage sig_handler(int signum) { int rc; switch (signum) { case SIGINT: case SIGTERM: exit(20 + signum); break; case SIGALRM: /* set flag, then write to pipe if needed */ run_msg_q = 1; goto do_write; break; case SIGCHLD: /* set flag, then write to pipe if needed */ sigchilds_waiting = 1; goto do_write; break; } do_write: /* if pipe is empty, write to pipe to force select to return * immediately when it gets called */ if (!sig_flag) { rc = write(pipefds[1],&signum,sizeof(signum)); if (rc >= 0) sig_flag = 1; } } static void udev_done(int pid) { /* find msg associated with pid and delete it */ struct hotplug_msg *msg; list_for_each_entry(msg, &running_list, list) { if (msg->pid == pid) { dbg("<== exec seq %llu came back", msg->seqnum); run_queue_delete(msg); /* we want to run the exec queue manager since there may * be events waiting with the devpath of the one that * just finished */ run_exec_q = 1; return; } } } static void reap_sigchilds(void) { while(1) { int pid = waitpid(-1, NULL, WNOHANG); if ((pid == -1) || (pid == 0)) break; udev_done(pid); } } /* just read everything from the pipe and clear the flag, * the flags was set in the signal handler */ static void user_sighandler(void) { int sig; while(1) { int rc = read(pipefds[0], &sig, sizeof(sig)); if (rc < 0) break; sig_flag = 0; } } int main(int argc, char *argv[], char *envp[]) { int maxsockplus; struct sockaddr_un saddr; socklen_t addrlen; int retval, fd; const int feature_on = 1; struct sigaction act; fd_set readfds; logging_init("udevd"); dbg("version %s", UDEV_VERSION); if (getuid() != 0) { dbg("need to be root, exit"); goto exit; } /* make sure we don't lock any path */ chdir("/"); umask(umask(077) | 022); /* Set fds to dev/null */ fd = open( "/dev/null", O_RDWR ); if ( fd < 0 ) { dbg("error opening /dev/null %s", strerror(errno)); goto exit; } dup2(fd, 0); dup2(fd, 1); dup2(fd, 2); if (fd > 2) close(fd); /* become session leader */ setsid(); /* setup signal handler pipe */ retval = pipe(pipefds); if (retval < 0) { dbg("error getting pipes: %s", strerror(errno)); goto exit; } retval = fcntl(pipefds[0], F_SETFL, O_NONBLOCK); if (retval < 0) { dbg("error fcntl on read pipe: %s", strerror(errno)); goto exit; } retval = fcntl(pipefds[0], F_SETFD, FD_CLOEXEC); if (retval < 0) { dbg("error fcntl on read pipe: %s", strerror(errno)); goto exit; } retval = fcntl(pipefds[1], F_SETFL, O_NONBLOCK); if (retval < 0) { dbg("error fcntl on write pipe: %s", strerror(errno)); goto exit; } retval = fcntl(pipefds[1], F_SETFD, FD_CLOEXEC); if (retval < 0) { dbg("error fcntl on write pipe: %s", strerror(errno)); goto exit; } /* set signal handlers */ act.sa_handler = (void (*) (int))sig_handler; sigemptyset(&act.sa_mask); act.sa_flags = SA_RESTART; sigaction(SIGINT, &act, NULL); sigaction(SIGTERM, &act, NULL); sigaction(SIGALRM, &act, NULL); sigaction(SIGCHLD, &act, NULL); memset(&saddr, 0x00, sizeof(saddr)); saddr.sun_family = AF_LOCAL; /* use abstract namespace for socket path */ strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH); addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1; udevsendsock = socket(AF_LOCAL, SOCK_DGRAM, 0); if (udevsendsock == -1) { dbg("error getting socket, exit"); goto exit; } /* the bind takes care of ensuring only one copy running */ retval = bind(udevsendsock, (struct sockaddr *) &saddr, addrlen); if (retval < 0) { dbg("bind failed, exit"); close(udevsendsock); goto exit; } /* enable receiving of the sender credentials */ setsockopt(udevsendsock, SOL_SOCKET, SO_PASSCRED, &feature_on, sizeof(feature_on)); /* possible override of udev binary, used for testing */ udev_bin = getenv("UDEV_BIN"); if (udev_bin != NULL) dbg("udev binary is set to '%s'", udev_bin); else udev_bin = UDEV_BIN; FD_ZERO(&readfds); FD_SET(udevsendsock, &readfds); FD_SET(pipefds[0], &readfds); maxsockplus = udevsendsock+1; while (1) { fd_set workreadfds = readfds; retval = select(maxsockplus, &workreadfds, NULL, NULL, NULL); if (retval < 0) { if (errno != EINTR) dbg("error in select: %s", strerror(errno)); continue; } if (FD_ISSET(udevsendsock, &workreadfds)) handle_udevsend_msg(udevsendsock); if (FD_ISSET(pipefds[0], &workreadfds)) user_sighandler(); if (sigchilds_waiting) { sigchilds_waiting = 0; reap_sigchilds(); } if (run_msg_q) { run_msg_q = 0; msg_queue_manager(); } if (run_exec_q) { /* clean up running_list before calling exec_queue_manager() */ if (sigchilds_waiting) { sigchilds_waiting = 0; reap_sigchilds(); } run_exec_q = 0; exec_queue_manager(); } } exit: logging_close(); return 1; }