diff options
Diffstat (limited to 'contrib/pf/pflogd/privsep.c')
| -rw-r--r-- | contrib/pf/pflogd/privsep.c | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/contrib/pf/pflogd/privsep.c b/contrib/pf/pflogd/privsep.c new file mode 100644 index 0000000..50807ad --- /dev/null +++ b/contrib/pf/pflogd/privsep.c @@ -0,0 +1,305 @@ +/* $OpenBSD: privsep.c,v 1.8 2004/03/14 19:17:05 otto Exp $ */ + +/* + * Copyright (c) 2003 Can Erkin Acar + * Copyright (c) 2003 Anil Madhavapeddy <anil@recoil.org> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ +#include <sys/ioctl.h> +#include <sys/types.h> +#include <sys/time.h> +#include <sys/socket.h> +#include <sys/ioctl.h> + +#include <net/if.h> +#include <net/bpf.h> + +#include <err.h> +#include <errno.h> +#include <fcntl.h> +#include <pcap.h> +#include <pcap-int.h> +#include <pwd.h> +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <syslog.h> +#include <unistd.h> +#include "pflogd.h" + +enum cmd_types { + PRIV_SET_SNAPLEN, /* set the snaplength */ + PRIV_OPEN_LOG /* open logfile for appending */ +}; + +static int priv_fd = -1; +static volatile pid_t child_pid = -1; + +volatile sig_atomic_t gotsig_chld = 0; + +static void sig_pass_to_chld(int); +static void sig_chld(int); +static int may_read(int, void *, size_t); +static void must_read(int, void *, size_t); +static void must_write(int, void *, size_t); +static int set_snaplen(int snap); + +/* bpf filter expression common to parent and child */ +extern char *filter; +extern char *errbuf; +extern char *filename; +extern pcap_t *hpcap; + +/* based on syslogd privsep */ +int +priv_init(void) +{ + int i, fd, socks[2], cmd; + int snaplen, ret; + struct passwd *pw; + + for (i = 1; i < _NSIG; i++) + signal(i, SIG_DFL); + + /* Create sockets */ + if (socketpair(AF_LOCAL, SOCK_STREAM, PF_UNSPEC, socks) == -1) + err(1, "socketpair() failed"); + + pw = getpwnam("_pflogd"); + if (pw == NULL) + errx(1, "unknown user _pflogd"); + endpwent(); + + child_pid = fork(); + if (child_pid < 0) + err(1, "fork() failed"); + + if (!child_pid) { + gid_t gidset[1]; + + /* Child - drop privileges and return */ + if (chroot(pw->pw_dir) != 0) + err(1, "unable to chroot"); + if (chdir("/") != 0) + err(1, "unable to chdir"); + + gidset[0] = pw->pw_gid; + if (setgroups(1, gidset) == -1) + err(1, "setgroups() failed"); + if (setegid(pw->pw_gid) == -1) + err(1, "setegid() failed"); + if (setgid(pw->pw_gid) == -1) + err(1, "setgid() failed"); + if (seteuid(pw->pw_uid) == -1) + err(1, "seteuid() failed"); + if (setuid(pw->pw_uid) == -1) + err(1, "setuid() failed"); + close(socks[0]); + priv_fd = socks[1]; + return 0; + } + + /* Father */ + /* Pass ALRM/TERM/HUP through to child, and accept CHLD */ + signal(SIGALRM, sig_pass_to_chld); + signal(SIGTERM, sig_pass_to_chld); + signal(SIGHUP, sig_pass_to_chld); + signal(SIGCHLD, sig_chld); + + setproctitle("[priv]"); + close(socks[1]); + + while (!gotsig_chld) { + if (may_read(socks[0], &cmd, sizeof(int))) + break; + switch (cmd) { + case PRIV_SET_SNAPLEN: + logmsg(LOG_DEBUG, + "[priv]: msg PRIV_SET_SNAPLENGTH received"); + must_read(socks[0], &snaplen, sizeof(int)); + + ret = set_snaplen(snaplen); + if (ret) { + logmsg(LOG_NOTICE, + "[priv]: set_snaplen failed for snaplen %d", + snaplen); + } + + must_write(socks[0], &ret, sizeof(int)); + break; + + case PRIV_OPEN_LOG: + logmsg(LOG_DEBUG, + "[priv]: msg PRIV_OPEN_LOG received"); + /* create or append logs but do not follow symlinks */ + fd = open(filename, + O_RDWR|O_CREAT|O_APPEND|O_NONBLOCK|O_NOFOLLOW, + 0600); + if (fd < 0) + logmsg(LOG_NOTICE, + "[priv]: failed to open %s: %s", + filename, strerror(errno)); + send_fd(socks[0], fd); + close(fd); + break; + + default: + logmsg(LOG_ERR, "[priv]: unknown command %d", cmd); + _exit(1); + /* NOTREACHED */ + } + } + + _exit(1); +} + +/* this is called from parent */ +static int +set_snaplen(int snap) +{ + if (hpcap == NULL) + return (1); + + hpcap->snapshot = snap; + set_pcap_filter(); + + return 0; +} + + +/* + * send the snaplength to privileged process + */ +int +priv_set_snaplen(int snaplen) +{ + int cmd, ret; + + if (priv_fd < 0) + errx(1, "%s: called from privileged portion", __func__); + + cmd = PRIV_SET_SNAPLEN; + + must_write(priv_fd, &cmd, sizeof(int)); + must_write(priv_fd, &snaplen, sizeof(int)); + + must_read(priv_fd, &ret, sizeof(int)); + + /* also set hpcap->snapshot in child */ + if (ret == 0) + hpcap->snapshot = snaplen; + + return (ret); +} + +/* Open log-file */ +int +priv_open_log(void) +{ + int cmd, fd; + + if (priv_fd < 0) + errx(1, "%s: called from privileged portion\n", __func__); + + cmd = PRIV_OPEN_LOG; + must_write(priv_fd, &cmd, sizeof(int)); + fd = receive_fd(priv_fd); + + return (fd); +} + +/* If priv parent gets a TERM or HUP, pass it through to child instead */ +static void +sig_pass_to_chld(int sig) +{ + int oerrno = errno; + + if (child_pid != -1) + kill(child_pid, sig); + errno = oerrno; +} + +/* if parent gets a SIGCHLD, it will exit */ +static void +sig_chld(int sig) +{ + gotsig_chld = 1; +} + +/* Read all data or return 1 for error. */ +static int +may_read(int fd, void *buf, size_t n) +{ + char *s = buf; + ssize_t res, pos = 0; + + while (n > pos) { + res = read(fd, s + pos, n - pos); + switch (res) { + case -1: + if (errno == EINTR || errno == EAGAIN) + continue; + case 0: + return (1); + default: + pos += res; + } + } + return (0); +} + +/* Read data with the assertion that it all must come through, or + * else abort the process. Based on atomicio() from openssh. */ +static void +must_read(int fd, void *buf, size_t n) +{ + char *s = buf; + ssize_t res, pos = 0; + + while (n > pos) { + res = read(fd, s + pos, n - pos); + switch (res) { + case -1: + if (errno == EINTR || errno == EAGAIN) + continue; + case 0: + _exit(0); + default: + pos += res; + } + } +} + +/* Write data with the assertion that it all has to be written, or + * else abort the process. Based on atomicio() from openssh. */ +static void +must_write(int fd, void *buf, size_t n) +{ + char *s = buf; + ssize_t res, pos = 0; + + while (n > pos) { + res = write(fd, s + pos, n - pos); + switch (res) { + case -1: + if (errno == EINTR || errno == EAGAIN) + continue; + case 0: + _exit(0); + default: + pos += res; + } + } +} |
