diff options
Diffstat (limited to 'dhcpcd/bpf.c')
| -rw-r--r-- | dhcpcd/bpf.c | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/dhcpcd/bpf.c b/dhcpcd/bpf.c new file mode 100644 index 00000000..59d17d92 --- /dev/null +++ b/dhcpcd/bpf.c @@ -0,0 +1,214 @@ +/* + * dhcpcd - DHCP client daemon + * Copyright (c) 2006-2014 Roy Marples <roy@marples.name> + * + * 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. 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 AUTHOR 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 AUTHOR 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 <sys/types.h> +#include <sys/time.h> +#include <sys/ioctl.h> +#include <sys/socket.h> +#include <sys/uio.h> + +#include <net/bpf.h> +#include <net/if.h> +#include <arpa/inet.h> + +#include <errno.h> +#include <fcntl.h> +#include <paths.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <syslog.h> +#include <unistd.h> + +#include "config.h" +#include "common.h" +#include "dhcp.h" +#include "ipv4.h" +#include "bpf-filter.h" + +int +ipv4_opensocket(struct interface *ifp, int protocol) +{ + struct dhcp_state *state; + int fd = -1; + struct ifreq ifr; + int buf_len = 0; + struct bpf_version pv; + struct bpf_program pf; +#ifdef BIOCIMMEDIATE + int flags; +#endif +#ifdef _PATH_BPF + fd = open(_PATH_BPF, O_RDWR | O_NONBLOCK); +#else + char *device; + int n = 0; + + device = malloc(sizeof(char) * PATH_MAX); + if (device == NULL) + return -1; + do { + snprintf(device, PATH_MAX, "/dev/bpf%d", n++); + fd = open(device, O_RDWR | O_NONBLOCK); + } while (fd == -1 && errno == EBUSY); + free(device); +#endif + + if (fd == -1) + return -1; + + state = D_STATE(ifp); + + if (ioctl(fd, BIOCVERSION, &pv) == -1) + goto eexit; + if (pv.bv_major != BPF_MAJOR_VERSION || + pv.bv_minor < BPF_MINOR_VERSION) { + syslog(LOG_ERR, "BPF version mismatch - recompile"); + goto eexit; + } + + memset(&ifr, 0, sizeof(ifr)); + strlcpy(ifr.ifr_name, ifp->name, sizeof(ifr.ifr_name)); + if (ioctl(fd, BIOCSETIF, &ifr) == -1) + goto eexit; + + /* Get the required BPF buffer length from the kernel. */ + if (ioctl(fd, BIOCGBLEN, &buf_len) == -1) + goto eexit; + if (state->buffer_size != (size_t)buf_len) { + free(state->buffer); + state->buffer = malloc(buf_len); + if (state->buffer == NULL) + goto eexit; + state->buffer_size = buf_len; + state->buffer_len = state->buffer_pos = 0; + } + +#ifdef BIOCIMMEDIATE + flags = 1; + if (ioctl(fd, BIOCIMMEDIATE, &flags) == -1) + goto eexit; +#endif + + /* Install the DHCP filter */ + if (protocol == ETHERTYPE_ARP) { + pf.bf_insns = UNCONST(arp_bpf_filter); + pf.bf_len = arp_bpf_filter_len; + } else { + pf.bf_insns = UNCONST(dhcp_bpf_filter); + pf.bf_len = dhcp_bpf_filter_len; + } + if (ioctl(fd, BIOCSETF, &pf) == -1) + goto eexit; + if (set_cloexec(fd) == -1) + goto eexit; + return fd; + +eexit: + free(state->buffer); + state->buffer = NULL; + close(fd); + return -1; +} + +ssize_t +ipv4_sendrawpacket(const struct interface *ifp, int protocol, + const void *data, ssize_t len) +{ + struct iovec iov[2]; + struct ether_header hw; + int fd; + const struct dhcp_state *state; + + memset(&hw, 0, ETHER_HDR_LEN); + memset(&hw.ether_dhost, 0xff, ETHER_ADDR_LEN); + hw.ether_type = htons(protocol); + iov[0].iov_base = &hw; + iov[0].iov_len = ETHER_HDR_LEN; + iov[1].iov_base = UNCONST(data); + iov[1].iov_len = len; + state = D_CSTATE(ifp); + if (protocol == ETHERTYPE_ARP) + fd = state->arp_fd; + else + fd = state->raw_fd; + return writev(fd, iov, 2); +} + +/* BPF requires that we read the entire buffer. + * So we pass the buffer in the API so we can loop on >1 packet. */ +ssize_t +ipv4_getrawpacket(struct interface *ifp, int protocol, + void *data, ssize_t len, int *partialcsum) +{ + int fd = -1; + struct bpf_hdr packet; + ssize_t bytes; + const unsigned char *payload; + struct dhcp_state *state; + + state = D_STATE(ifp); + if (protocol == ETHERTYPE_ARP) + fd = state->arp_fd; + else + fd = state->raw_fd; + + if (partialcsum != NULL) + *partialcsum = 0; /* Not supported on BSD */ + + for (;;) { + if (state->buffer_len == 0) { + bytes = read(fd, state->buffer, state->buffer_size); + if (bytes == -1) + return errno == EAGAIN ? 0 : -1; + else if ((size_t)bytes < sizeof(packet)) + return -1; + state->buffer_len = bytes; + state->buffer_pos = 0; + } + bytes = -1; + memcpy(&packet, state->buffer + state->buffer_pos, + sizeof(packet)); + if (packet.bh_caplen != packet.bh_datalen) + goto next; /* Incomplete packet, drop. */ + if (state->buffer_pos + packet.bh_caplen + packet.bh_hdrlen > + state->buffer_len) + goto next; /* Packet beyond buffer, drop. */ + payload = state->buffer + state->buffer_pos + + packet.bh_hdrlen + ETHER_HDR_LEN; + bytes = packet.bh_caplen - ETHER_HDR_LEN; + if (bytes > len) + bytes = len; + memcpy(data, payload, bytes); +next: + state->buffer_pos += BPF_WORDALIGN(packet.bh_hdrlen + + packet.bh_caplen); + if (state->buffer_pos >= state->buffer_len) + state->buffer_len = state->buffer_pos = 0; + if (bytes != -1) + return bytes; + } +} |