/* $OpenBSD: cvsd.c,v 1.16 2004/12/14 19:53:12 xsa Exp $ */ /* * Copyright (c) 2004 Jean-Francois Brousseau * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "log.h" #include "sock.h" #include "cvs.h" #include "cvsd.h" static void cvsd_parent_loop (void); static void cvsd_child_main (void); static int cvsd_privdrop (void); static void cvsd_report (void); extern char *__progname; int cvsd_fg = 0; uid_t cvsd_uid = -1; gid_t cvsd_gid = -1; volatile sig_atomic_t cvsd_running = 1; volatile sig_atomic_t cvsd_restart = 0; static char *cvsd_user = NULL; static char *cvsd_group = NULL; static char *cvsd_root = NULL; static char *cvsd_conffile = CVSD_CONF; static char *cvsd_moddir = NULL; static int cvsd_privfd = -1; static TAILQ_HEAD(,cvsd_child) cvsd_children; static volatile sig_atomic_t cvsd_chnum = 0; static volatile sig_atomic_t cvsd_chmin = CVSD_CHILD_DEFMIN; static volatile sig_atomic_t cvsd_chmax = CVSD_CHILD_DEFMAX; static volatile sig_atomic_t cvsd_sigchld = 0; static volatile sig_atomic_t cvsd_siginfo = 0; void usage (void); void cvsd_sighdlr (int); int cvsd_msghdlr (struct cvsd_child *, int); /* * cvsd_sighdlr() * * Generic signal handler. */ void cvsd_sighdlr(int signo) { switch (signo) { case SIGHUP: cvsd_restart = 1; break; case SIGCHLD: cvsd_sigchld = 1; break; case SIGINT: case SIGTERM: case SIGQUIT: cvsd_running = 0; break; case SIGINFO: cvsd_siginfo = 1; break; } } /* * usage() * * Display program usage. */ void usage(void) { fprintf(stderr, "Usage: %s [-dfhpv] [-c config] [-g group] [-r root] " "[-s path] [-u user]\n" "\t-c config\tUse as the configuration file\n" "\t-d\t\tStart the server in debugging mode (very verbose)\n" "\t-f\t\tStay in foreground instead of becoming a daemon\n" "\t-g group\tUse group for privilege revocation\n" "\t-h\t\tPrint the usage and exit\n" "\t-p\t\tPerform repository sanity check on startup\n" "\t-r root\t\tUse as the root directory of the repository\n" "\t-s path\t\tUse as the path for the CVS server socket\n" "\t-u user\t\tUse user for privilege revocation\n" "\t-v\t\tBe verbose\n", __progname); } int main(int argc, char **argv) { u_int i; int ret, checkrepo; struct passwd *pwd; struct group *grp; checkrepo = 0; cvsd_set(CVSD_SET_USER, CVSD_USER); cvsd_set(CVSD_SET_GROUP, CVSD_GROUP); if (cvs_log_init(LD_STD|LD_SYSLOG, LF_PID) < 0) err(1, "failed to initialize logging mechanism"); while ((ret = getopt(argc, argv, "a:c:dfhpr:s:v")) != -1) { switch (ret) { case 'c': cvsd_conffile = optarg; break; case 'd': cvs_log_filter(LP_FILTER_UNSET, LP_DEBUG); cvs_log_filter(LP_FILTER_UNSET, LP_INFO); break; case 'f': cvsd_fg = 1; break; case 'g': cvsd_set(CVSD_SET_GROUP, optarg); break; case 'h': usage(); exit(0); /* NOTREACHED */ break; case 'p': checkrepo = 1; break; case 'r': cvsd_root = optarg; break; case 's': cvsd_sock_path = optarg; break; case 'u': cvsd_set(CVSD_SET_USER, optarg); break; case 'v': cvs_log_filter(LP_FILTER_UNSET, LP_INFO); break; default: usage(); exit(EX_USAGE); } } argc -= optind; argv += optind; if (cvs_conf_read(cvsd_conffile) < 0) errx(1, "error parsing configuration file `%s'", cvsd_conffile); if (cvsd_root == NULL) errx(1, "no CVS root directory specified"); if (argc > 0) errx(EX_USAGE, "unrecognized trailing arguments"); TAILQ_INIT(&cvsd_children); pwd = getpwnam(cvsd_user); if (pwd == NULL) err(EX_NOUSER, "failed to get user `%s'", cvsd_user); grp = getgrnam(cvsd_group); if (grp == NULL) err(EX_NOUSER, "failed to get group `%s'", cvsd_group); cvsd_uid = pwd->pw_uid; cvsd_gid = grp->gr_gid; signal(SIGHUP, cvsd_sighdlr); signal(SIGINT, cvsd_sighdlr); signal(SIGQUIT, cvsd_sighdlr); signal(SIGTERM, cvsd_sighdlr); signal(SIGCHLD, cvsd_sighdlr); signal(SIGPIPE, SIG_IGN); if (!cvsd_fg && daemon(0, 0) == -1) { cvs_log(LP_ERRNO, "failed to become a daemon"); exit(EX_OSERR); } if (cvsd_sock_open() < 0) { exit(1); } if (setegid(cvsd_gid) == -1) { cvs_log(LP_ERRNO, "failed to drop group privileges"); exit(EX_OSERR); } if (seteuid(cvsd_uid) == -1) { cvs_log(LP_ERRNO, "failed to drop user privileges"); exit(EX_OSERR); } if (checkrepo && cvsd_checkperms("/") != 0) { cvs_log(LP_ERR, "exiting due to permission errors on repository"); exit(1); } /* spawn the initial pool of children */ for (i = 0; i < (u_int)cvsd_chmin; i++) if (cvsd_child_fork(NULL) < 0) exit(EX_OSERR); signal(SIGINFO, cvsd_sighdlr); cvsd_parent_loop(); cvs_log(LP_NOTICE, "shutting down"); cvs_log_cleanup(); cvsd_sock_close(); return (0); } /* * cvsd_privdrop() * * Drop privileges. */ int cvsd_privdrop(void) { cvs_log(LP_INFO, "dropping privileges to %s[%d]:%s[%d]", cvsd_user, cvsd_uid, cvsd_group, cvsd_gid); if (setgid(cvsd_gid) == -1) { cvs_log(LP_ERRNO, "failed to drop group privileges to %s", CVSD_GROUP); return (-1); } if (setuid(cvsd_uid) == -1) { cvs_log(LP_ERRNO, "failed to drop user privileges to %s", CVSD_USER); return (-1); } return (0); } /* * cvsd_checkperms() * * Check permissions on the CVS repository and log warnings for any * weird of loose permissions. * Returns the number of warnings on success, or -1 on failure. */ int cvsd_checkperms(const char *path) { int fd, nbwarn, ret; mode_t fmode; long base; u_char *dp, *endp; char buf[1024], spath[MAXPATHLEN]; struct stat st; struct dirent *dep; nbwarn = 0; cvs_log(LP_DEBUG, "checking permissions on `%s'", path); if (stat(path, &st) == -1) { cvs_log(LP_ERRNO, "failed to stat `%s'", path); return (-1); } if (S_ISDIR(st.st_mode)) fmode = CVSD_DPERM; else fmode = CVSD_FPERM; if (st.st_uid != cvsd_uid) { cvs_log(LP_WARN, "owner of `%s' is not %s", path, CVSD_USER); nbwarn++; } if (st.st_gid != cvsd_gid) { cvs_log(LP_WARN, "group of `%s' is not %s", path, CVSD_GROUP); nbwarn++; } if (st.st_mode & S_IWGRP) { cvs_log(LP_WARN, "file `%s' is group-writable", path, fmode); nbwarn++; } if (st.st_mode & S_IWOTH) { cvs_log(LP_WARN, "file `%s' is world-writable", path, fmode); nbwarn++; } if (S_ISDIR(st.st_mode)) { fd = open(path, O_RDONLY, 0); if (fd == -1) { cvs_log(LP_ERRNO, "failed to open directory `%s'", path); return (nbwarn); } /* recurse */ ret = getdirentries(fd, buf, sizeof(buf), &base); if (ret == -1) { cvs_log(LP_ERRNO, "failed to get directory entries for `%s'", path); (void)close(fd); return (nbwarn); } dp = buf; endp = buf + ret; while (dp < endp) { dep = (struct dirent *)dp; dp += dep->d_reclen; if ((dep->d_namlen == 1) && (dep->d_name[0] == '.')) continue; if ((dep->d_namlen == 2) && (dep->d_name[0] == '.') && (dep->d_name[1] == '.')) continue; /* skip the CVSROOT directory */ if (strcmp(dep->d_name, CVS_PATH_ROOT) == 0) continue; snprintf(spath, sizeof(spath), "%s/%s", path, dep->d_name); ret = cvsd_checkperms(spath); if (ret == -1) nbwarn++; else nbwarn += ret; } (void)close(fd); } return (nbwarn); } /* * cvsd_child_fork() * * Fork a child process which chroots to the CVS repository's root directory. * If the argument is not NULL, a reference to the newly created child * structure will be returned. * On success, returns 0 in the child process context, 1 in the parent's * context, or -1 on failure. */ int cvsd_child_fork(struct cvsd_child **chpp) { int svec[2]; pid_t pid; struct cvsd_child *chp; if (cvsd_chnum == cvsd_chmax) { cvs_log(LP_WARN, "child pool reached limit of processes"); return (-1); } if (socketpair(AF_LOCAL, SOCK_STREAM, PF_UNSPEC, svec) == -1) { cvs_log(LP_ERRNO, "failed to create socket pair"); return (-1); } /* * We need to temporarily regain original privileges in order for the * child to chroot(). */ if (seteuid(0) == -1) { cvs_log(LP_ERRNO, "failed to regain privileges"); return (-1); } pid = fork(); if (pid == -1) { cvs_log(LP_ERRNO, "failed to fork child"); (void)close(svec[0]); (void)close(svec[1]); return (-1); } if (pid == 0) { cvsd_privfd = svec[1]; (void)close(svec[0]); cvsd_child_main(); /* NOTREACHED */ } cvs_log(LP_INFO, "spawning child %d", pid); if (seteuid(cvsd_uid) == -1) { cvs_log(LP_ERRNO, "failed to redrop privs"); return (-1); } chp = (struct cvsd_child *)malloc(sizeof(*chp)); if (chp == NULL) { cvs_log(LP_ERRNO, "failed to allocate child data"); return (-1); } chp->ch_pid = pid; chp->ch_sock = svec[0]; chp->ch_state = CVSD_ST_IDLE; signal(SIGCHLD, SIG_IGN); TAILQ_INSERT_TAIL(&cvsd_children, chp, ch_list); cvsd_chnum++; signal(SIGCHLD, cvsd_sighdlr); if (chpp != NULL) *chpp = chp; (void)close(svec[1]); return (1); } /* * cvsd_child_reap() * * Wait for a child's status and perform the proper actions depending on it. * If the child has exited or has been terminated by a signal, it will be * removed from the list and new children will be created until the pool has * at least children in it. * Returns 0 on success, or -1 on failure. */ int cvsd_child_reap(void) { pid_t pid; int status; struct cvsd_child *ch; pid = wait(&status); if (pid == -1) { cvs_log(LP_ERRNO, "failed to wait for child"); return (-1); } TAILQ_FOREACH(ch, &cvsd_children, ch_list) { if (ch->ch_pid == pid) { if (WIFEXITED(status)) { cvs_log(LP_WARN, "child %d exited with status %d", pid, WEXITSTATUS(status)); } else if (WIFSIGNALED(status)) { cvs_log(LP_WARN, "child %d terminated with signal %d", pid, WTERMSIG(status)); } else { cvs_log(LP_ERR, "HOLY SHIT!"); } signal(SIGCHLD, SIG_IGN); TAILQ_REMOVE(&cvsd_children, ch, ch_list); cvsd_chnum--; signal(SIGCHLD, cvsd_sighdlr); break; } } while (cvsd_chnum < cvsd_chmin) cvsd_child_fork(NULL); return (0); } /* * cvsd_child_get() * * Find a child process in idle state and return a pointer to the child's * structure. If there are no available child processes, a new one will be * created unless the number of children has attained the maximum, in which * case NULL is returned. */ struct cvsd_child* cvsd_child_get(void) { struct cvsd_child *chp; TAILQ_FOREACH(chp, &cvsd_children, ch_list) if (chp->ch_state == CVSD_ST_IDLE) return (chp); /* no available child, attempt to fork a new one */ chp = NULL; if ((cvsd_chnum < cvsd_chmax) && (cvsd_child_fork(&chp) < 0)) return (NULL); return (chp); } /* * cvsd_parent_loop() * * Main loop of the parent cvsd process, which listens on its end of the * local socket for requests from the cvs(1) program and on any outstanding * messages from the children. */ static void cvsd_parent_loop(void) { int cfd, timeout, ret; nfds_t nfds, i; struct pollfd *pfd; struct cvsd_child *chp; nfds = 0; timeout = INFTIM; pfd = NULL; for (;;) { if (!cvsd_running) break; if (cvsd_restart) { /* restart server */ } if (cvsd_sigchld) { cvsd_sigchld = 0; cvsd_child_reap(); } if (cvsd_siginfo) { cvsd_siginfo = 0; cvsd_report(); } nfds = cvsd_chnum + 1; pfd = (struct pollfd *)realloc(pfd, nfds * sizeof(struct pollfd)); if (pfd == NULL) { cvs_log(LP_ERRNO, "failed to reallocate polling data"); return; } pfd[0].fd = cvsd_sock; pfd[0].events = POLLIN; pfd[0].revents = 0; i = 1; TAILQ_FOREACH(chp, &cvsd_children, ch_list) { pfd[i].fd = chp->ch_sock; pfd[i].events = POLLIN; pfd[i].revents = 0; i++; if (i == nfds) /* just a precaution */ break; } ret = poll(pfd, nfds, timeout); if (ret == -1) { if (errno == EINTR) continue; cvs_log(LP_ERRNO, "poll error"); break; } if (pfd[0].revents & (POLLERR|POLLNVAL)) { cvs_log(LP_ERR, "poll error on request socket"); } else if (pfd[0].revents & POLLIN) { uid_t uid; gid_t gid; cfd = cvsd_sock_accept(pfd[0].fd); if (cfd == -1) chp = cvsd_child_get(); if (chp == NULL) { cvs_log(LP_ALERT, "request queue not implemented"); break; } if (getpeereid(cfd, &uid, &gid) < 0) err(1, "failed to get UID"); if (cvsd_sendmsg(chp->ch_sock, CVSD_MSG_PASSFD, &cfd, sizeof(cfd)) < 0) break; /* mark the child as busy */ chp->ch_state = CVSD_ST_BUSY; } chp = TAILQ_FIRST(&cvsd_children); for (i = 1; i < nfds; i++) { if (pfd[i].revents & (POLLERR|POLLNVAL)) { cvs_log(LP_ERR, "poll error on child socket (PID %d)", chp->ch_pid); } else if (pfd[i].revents & POLLIN) cvsd_msghdlr(chp, pfd[i].fd); chp = TAILQ_NEXT(chp, ch_list); } } /* broadcast a shutdown message to children */ TAILQ_FOREACH(chp, &cvsd_children, ch_list) { (void)cvsd_sendmsg(chp->ch_sock, CVSD_MSG_SHUTDOWN, NULL, 0); } } /* * cvsd_child_main() * */ static void cvsd_child_main(void) { int ret, timeout; u_int mtype; size_t mlen; char mbuf[CVSD_MSG_MAXLEN]; struct pollfd pfd[1]; struct cvsd_sess *sessp; cvs_log(LP_INFO, "changing root to %s", cvsd_root); if (chroot(cvsd_root) == -1) { cvs_log(LP_ERRNO, "failed to chroot to `%s'", cvsd_root); exit(EX_OSERR); } (void)chdir("/"); if (cvsd_privdrop() < 0) exit(EX_OSERR); setproctitle("%s [child %d]", __progname, getpid()); pfd[0].fd = cvsd_privfd; pfd[0].events = POLLIN; timeout = INFTIM; sessp = NULL; while (cvsd_running) { ret = poll(pfd, 1, timeout); if (ret == -1) { if (errno == EINTR) continue; cvs_log(LP_ERRNO, "poll error"); break; } else if (ret == 0) continue; if (pfd[0].revents & (POLLERR|POLLNVAL)) { cvs_log(LP_ERR, "poll error"); break; } mlen = sizeof(mbuf); ret = cvsd_recvmsg(pfd[0].fd, &mtype, mbuf, &mlen); if (ret == -1) { continue; } else if (ret == 0) break; switch (mtype) { case CVSD_MSG_PASSFD: sessp = cvsd_sess_alloc(*(int *)mbuf); break; case CVSD_MSG_SHUTDOWN: cvsd_running = 0; break; default: cvs_log(LP_ERR, "unexpected message type %u from parent", mtype); break; } } exit(0); } /* * cvsd_msghdlr() * * Handler for messages received from child processes. * Returns 0 on success, or -1 on failure. */ int cvsd_msghdlr(struct cvsd_child *child, int fd) { uid_t uid; ssize_t ret; char rbuf[CVSD_MSG_MAXLEN]; struct group *gr; struct passwd *pw; struct iovec iov[2]; struct cvsd_msg msg; ret = read(fd, &msg, sizeof(msg)); if (ret == -1) { cvs_log(LP_ERRNO, "failed to read CVS message"); return (-1); } else if (ret == 0) { cvs_log(LP_WARN, "child closed socket pair"); return (0); } if (msg.cm_len > 0) { ret = read(fd, rbuf, msg.cm_len); if (ret != (ssize_t)msg.cm_len) { cvs_log(LP_ERR, "failed to read entire msg"); return (-1); } } /* setup the I/O vector for the reply */ iov[0].iov_base = &msg; iov[0].iov_len = sizeof(msg); msg.cm_type = CVSD_MSG_ERROR; msg.cm_len = 0; switch (msg.cm_type) { case CVSD_MSG_GETUID: rbuf[ret] = '\0'; cvs_log(LP_INFO, "getting UID for `%s'", rbuf); pw = getpwnam(rbuf); if (pw != NULL) { msg.cm_type = CVSD_MSG_UID; msg.cm_len = sizeof(uid_t); iov[1].iov_len = msg.cm_len; iov[1].iov_base = &(pw->pw_uid); } break; case CVSD_MSG_GETUNAME: memcpy(&uid, rbuf, sizeof(uid)); cvs_log(LP_INFO, "getting username for UID %u", uid); pw = getpwuid(uid); if (pw != NULL) { msg.cm_type = CVSD_MSG_UNAME; msg.cm_len = strlen(pw->pw_name); iov[1].iov_len = msg.cm_len; iov[1].iov_base = pw->pw_name; } break; case CVSD_MSG_GETGID: rbuf[ret] = '\0'; cvs_log(LP_INFO, "getting GID for `%s'", rbuf); gr = getgrnam(rbuf); if (gr != NULL) { msg.cm_type = CVSD_MSG_GID; msg.cm_len = sizeof(gid_t); iov[1].iov_len = msg.cm_len; iov[1].iov_base = &(gr->gr_gid); } break; case CVSD_MSG_SETIDLE: child->ch_state = CVSD_ST_IDLE; break; default: cvs_log(LP_ERR, "unknown command type %u", msg.cm_type); return (-1); } ret = writev(fd, iov, 2); return (ret); } /* * cvsd_set() * * Generic interface to set some of the parameters of the cvs server. * When a string is set using cvsd_set(), the original string is copied into * a new buffer. * Returns 0 on success, or -1 on failure. */ int cvsd_set(int what, ...) { char *str; int error = 0; va_list vap; str = NULL; va_start(vap, what); if ((what == CVSD_SET_ROOT) || (what == CVSD_SET_SOCK) || (what == CVSD_SET_USER) || (what == CVSD_SET_GROUP) || (what == CVSD_SET_MODDIR)) { str = strdup(va_arg(vap, char *)); if (str == NULL) { cvs_log(LP_ERRNO, "failed to set string"); va_end(vap); return (-1); } } switch (what) { case CVSD_SET_ROOT: if (cvsd_root != NULL) free(cvsd_root); cvsd_root = str; break; case CVSD_SET_SOCK: if (cvsd_sock_path != NULL) free(cvsd_sock_path); cvsd_sock_path = str; error = cvsd_sock_open(); break; case CVSD_SET_USER: if (cvsd_user != NULL) free(cvsd_user); cvsd_user = str; break; case CVSD_SET_GROUP: if (cvsd_group != NULL) free(cvsd_group); cvsd_group = str; break; case CVSD_SET_MODDIR: if (cvsd_moddir != NULL) free(cvsd_moddir); cvsd_moddir = str; break; case CVSD_SET_CHMIN: cvsd_chmin = va_arg(vap, int); /* we should increase the number of children accordingly */ break; case CVSD_SET_CHMAX: cvsd_chmax = va_arg(vap, int); /* we should decrease the number of children accordingly */ break; case CVSD_SET_ADDR: /* this is more like an add than a set */ break; default: cvs_log(LP_ERR, "invalid field to set"); error = -1; break; } va_end(vap); return (error); } /* * cvsd_report() */ static void cvsd_report(void) { u_int nb_idle, nb_busy, nb_unknown; struct cvsd_child *ch; nb_idle = 0; nb_busy = 0; nb_unknown = 0; signal(SIGCHLD, SIG_IGN); TAILQ_FOREACH(ch, &cvsd_children, ch_list) { if (ch->ch_state == CVSD_ST_IDLE) nb_idle++; else if (ch->ch_state == CVSD_ST_BUSY) nb_busy++; else if (ch->ch_state == CVSD_ST_UNKNOWN) nb_unknown++; } cvs_log(LP_WARN, "%u children, %u idle, %u busy, %u unknown", cvsd_chnum, nb_idle, nb_busy, nb_unknown); TAILQ_FOREACH(ch, &cvsd_children, ch_list) cvs_log(LP_WARN, ""); signal(SIGCHLD, cvsd_sighdlr); }