/* $OpenBSD: privsep_pcap.c,v 1.23 2018/11/17 16:52:02 brynet Exp $ */ /* * Copyright (c) 2004 Can Erkin Acar * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * - Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following * disclaimer in the documentation and/or other materials provided * with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "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 * COPYRIGHT HOLDERS OR CONTRIBUTORS 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 "privsep.h" /* * privileged part of priv_pcap_setfilter, compile the filter * expression, and return it to the parent. Note that we fake an hpcap * and use it to capture the error messages, and pass the error back * to client. */ int setfilter(int bpfd, int sock, char *filter) { struct bpf_program fcode; int oflag, snap, link; u_int32_t netmask; pcap_t hpcap; must_read(sock, &oflag, sizeof(oflag)); must_read(sock, &netmask, sizeof(netmask)); must_read(sock, &snap, sizeof(snap)); must_read(sock, &link, sizeof(link)); if (snap < 0) { snprintf(hpcap.errbuf, PCAP_ERRBUF_SIZE, "invalid snaplen"); goto err; } /* fake hpcap, it only needs errbuf, snaplen, and linktype to * compile a filter expression */ /* XXX messing with pcap internals */ hpcap.snapshot = snap; hpcap.linktype = link; if (pcap_compile(&hpcap, &fcode, filter, oflag, netmask)) goto err; /* if bpf descriptor is open, set the filter XXX check oflag? */ if (bpfd >= 0 && ioctl(bpfd, BIOCSETF, &fcode)) { snprintf(hpcap.errbuf, PCAP_ERRBUF_SIZE, "ioctl: BIOCSETF: %s", strerror(errno)); pcap_freecode(&fcode); goto err; } if (fcode.bf_len > 0) { /* write the filter */ must_write(sock, &fcode.bf_len, sizeof(fcode.bf_len)); must_write(sock, fcode.bf_insns, fcode.bf_len * sizeof(struct bpf_insn)); } else { snprintf(hpcap.errbuf, PCAP_ERRBUF_SIZE, "Invalid filter size"); pcap_freecode(&fcode); goto err; } pcap_freecode(&fcode); return (0); err: fcode.bf_len = 0; must_write(sock, &fcode.bf_len, sizeof(fcode.bf_len)); /* write back the error string */ write_string(sock, hpcap.errbuf); return (1); } /* * filter is compiled and set in the privileged process. * get the compiled output and set it locally for filtering dumps etc. */ struct bpf_program * priv_pcap_setfilter(pcap_t *hpcap, int oflag, u_int32_t netmask) { struct bpf_program *fcode = NULL; int snap, link; char *ebuf; if (priv_fd < 0) errx(1, "%s: called from privileged portion", __func__); ebuf = pcap_geterr(hpcap); snap = pcap_snapshot(hpcap); link = pcap_datalink(hpcap); fcode = calloc(1, sizeof(*fcode)); if (fcode == NULL) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "out of memory"); return (NULL); } write_command(priv_fd, PRIV_SETFILTER); /* send oflag, netmask, snaplen and linktype */ must_write(priv_fd, &oflag, sizeof(oflag)); must_write(priv_fd, &netmask, sizeof(netmask)); must_write(priv_fd, &snap, sizeof(snap)); must_write(priv_fd, &link, sizeof(link)); /* receive compiled filter */ must_read(priv_fd, &fcode->bf_len, sizeof(fcode->bf_len)); if (fcode->bf_len <= 0) { int len; len = read_string(priv_fd, ebuf, PCAP_ERRBUF_SIZE, __func__); if (len == 0) snprintf(ebuf, PCAP_ERRBUF_SIZE, "pcap compile error"); goto err; } fcode->bf_insns = calloc(fcode->bf_len, sizeof(struct bpf_insn)); if (fcode->bf_insns == NULL) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "out of memory"); goto err; } must_read(priv_fd, fcode->bf_insns, fcode->bf_len * sizeof(struct bpf_insn)); pcap_setfilter(hpcap, fcode); return (fcode); err: free(fcode); return (NULL); } /* privileged part of priv_pcap_live */ int pcap_live(const char *device, int snaplen, int promisc, u_int dlt, u_int dirfilt) { int fd; struct ifreq ifr; unsigned v; if (device == NULL || snaplen <= 0) return (-1); if ((fd = open("/dev/bpf", O_RDONLY)) == -1) return (-1); v = 32768; /* XXX this should be a user-accessible hook */ ioctl(fd, BIOCSBLEN, &v); strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); if (ioctl(fd, BIOCSETIF, &ifr) < 0) goto error; if (dlt != (u_int) -1 && ioctl(fd, BIOCSDLT, &dlt)) goto error; if (promisc) /* this is allowed to fail */ ioctl(fd, BIOCPROMISC, NULL); if (ioctl(fd, BIOCSDIRFILT, &dirfilt) < 0) goto error; /* lock the descriptor */ if (ioctl(fd, BIOCLOCK, NULL) < 0) goto error; return (fd); error: close(fd); return (-1); } /* * XXX reimplement pcap_open_live with privsep, this is the * unprivileged part. */ pcap_t * priv_pcap_live(const char *dev, int slen, int prom, int to_ms, char *ebuf, u_int dlt, u_int dirfilt) { int fd, err; struct bpf_version bv; u_int v; pcap_t *p; if (priv_fd < 0) errx(1, "%s: called from privileged portion", __func__); if (dev == NULL) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "No interface specified"); return (NULL); } p = malloc(sizeof(*p)); if (p == NULL) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s", pcap_strerror(errno)); return (NULL); } bzero(p, sizeof(*p)); write_command(priv_fd, PRIV_OPEN_BPF); must_write(priv_fd, &slen, sizeof(int)); must_write(priv_fd, &prom, sizeof(int)); must_write(priv_fd, &dlt, sizeof(u_int)); must_write(priv_fd, &dirfilt, sizeof(u_int)); write_string(priv_fd, dev); fd = receive_fd(priv_fd); must_read(priv_fd, &err, sizeof(int)); if (fd < 0) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "Failed to open bpf device for %s: %s", dev, strerror(err)); goto bad; } /* fd is locked, can only use 'safe' ioctls */ if (ioctl(fd, BIOCVERSION, &bv) < 0) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCVERSION: %s", pcap_strerror(errno)); goto bad; } if (bv.bv_major != BPF_MAJOR_VERSION || bv.bv_minor < BPF_MINOR_VERSION) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "kernel bpf filter out of date"); goto bad; } p->fd = fd; p->snapshot = slen; /* Get the data link layer type. */ if (ioctl(fd, BIOCGDLT, &v) < 0) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCGDLT: %s", pcap_strerror(errno)); goto bad; } p->linktype = v; /* XXX hack */ if (p->linktype == DLT_PFLOG && p->snapshot < 160) p->snapshot = 160; /* set timeout */ if (to_ms != 0) { struct timeval to; to.tv_sec = to_ms / 1000; to.tv_usec = (to_ms * 1000) % 1000000; if (ioctl(p->fd, BIOCSRTIMEOUT, &to) < 0) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSRTIMEOUT: %s", pcap_strerror(errno)); goto bad; } } if (ioctl(fd, BIOCGBLEN, &v) < 0) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCGBLEN: %s", pcap_strerror(errno)); goto bad; } p->bufsize = v; p->buffer = malloc(p->bufsize); if (p->buffer == NULL) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s", pcap_strerror(errno)); goto bad; } return (p); bad: if (fd >= 0) close(fd); free(p); return (NULL); } /* * reimplement pcap_open_offline with privsep, this is the * unprivileged part. * XXX merge with above? */ static void swap_hdr(struct pcap_file_header *hp) { hp->version_major = swap16(hp->version_major); hp->version_minor = swap16(hp->version_minor); hp->thiszone = swap32(hp->thiszone); hp->sigfigs = swap32(hp->sigfigs); hp->snaplen = swap32(hp->snaplen); hp->linktype = swap32(hp->linktype); } pcap_t * priv_pcap_offline(const char *fname, char *errbuf) { pcap_t *p; FILE *fp = NULL; struct pcap_file_header hdr; int linklen, err; if (priv_fd < 0) errx(1, "%s: called from privileged portion", __func__); p = malloc(sizeof(*p)); if (p == NULL) { strlcpy(errbuf, "out of swap", PCAP_ERRBUF_SIZE); return (NULL); } memset((char *)p, 0, sizeof(*p)); if (fname[0] == '-' && fname[1] == '\0') { p->fd = -1; fp = stdin; } else { write_command(priv_fd, PRIV_OPEN_DUMP); p->fd = receive_fd(priv_fd); must_read(priv_fd, &err, sizeof(int)); if (p->fd < 0) { snprintf(errbuf, PCAP_ERRBUF_SIZE, "Failed to open input file %s: %s", fname, strerror(err)); goto bad; } fp = fdopen(p->fd, "r"); if (fp == NULL) { snprintf(errbuf, PCAP_ERRBUF_SIZE, "%s: %s", fname, pcap_strerror(errno)); close(p->fd); p->fd = -1; goto bad; } } if (fread((char *)&hdr, sizeof(hdr), 1, fp) != 1) { snprintf(errbuf, PCAP_ERRBUF_SIZE, "fread: %s", pcap_strerror(errno)); goto bad; } if (hdr.magic != TCPDUMP_MAGIC) { if (swap32(hdr.magic) != TCPDUMP_MAGIC) { snprintf(errbuf, PCAP_ERRBUF_SIZE, "bad dump file format"); goto bad; } p->sf.swapped = 1; swap_hdr(&hdr); } if (hdr.version_major < PCAP_VERSION_MAJOR) { snprintf(errbuf, PCAP_ERRBUF_SIZE, "archaic file format"); goto bad; } p->tzoff = hdr.thiszone; p->snapshot = hdr.snaplen; p->linktype = hdr.linktype; p->sf.rfile = fp; p->bufsize = hdr.snaplen; /* Align link header as required for proper data alignment */ /* XXX should handle all types */ switch (p->linktype) { case DLT_EN10MB: linklen = 14; break; case DLT_FDDI: linklen = 13 + 8; /* fddi_header + llc */ break; case DLT_NULL: default: linklen = 0; break; } if (p->bufsize < 0) p->bufsize = BPF_MAXBUFSIZE; p->sf.base = malloc(p->bufsize + BPF_ALIGNMENT); if (p->sf.base == NULL) { strlcpy(errbuf, "out of swap", PCAP_ERRBUF_SIZE); goto bad; } p->buffer = p->sf.base + BPF_ALIGNMENT - (linklen % BPF_ALIGNMENT); p->sf.version_major = hdr.version_major; p->sf.version_minor = hdr.version_minor; #ifdef PCAP_FDDIPAD /* XXX what to do with this? */ /* XXX padding only needed for kernel fcode */ pcap_fddipad = 0; #endif return (p); bad: if (fp != NULL && p->fd != -1) fclose(fp); free(p); return (NULL); } static int sf_write_header(FILE *fp, int linktype, int thiszone, int snaplen) { struct pcap_file_header hdr; bzero(&hdr, sizeof hdr); hdr.magic = TCPDUMP_MAGIC; hdr.version_major = PCAP_VERSION_MAJOR; hdr.version_minor = PCAP_VERSION_MINOR; hdr.thiszone = thiszone; hdr.snaplen = snaplen; hdr.sigfigs = 0; hdr.linktype = linktype; if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1) return (-1); return (0); } pcap_dumper_t * priv_pcap_dump_open(pcap_t *p, char *fname) { int fd, err; FILE *f; if (priv_fd < 0) errx(1, "%s: called from privileged portion", __func__); if (fname[0] == '-' && fname[1] == '\0') f = stdout; else { write_command(priv_fd, PRIV_OPEN_OUTPUT); fd = receive_fd(priv_fd); must_read(priv_fd, &err, sizeof(err)); if (fd < 0) { snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "Failed to open output file %s: %s", fname, strerror(err)); return (NULL); } f = fdopen(fd, "w"); if (f == NULL) { snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "%s: %s", fname, pcap_strerror(errno)); close(fd); return (NULL); } } priv_init_done(); (void)sf_write_header(f, p->linktype, p->tzoff, p->snapshot); return ((pcap_dumper_t *)f); }