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pcap-linux.c
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pcap-linux.c
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/*
* pcap-linux.c: Packet capture interface to the Linux kernel
*
* Copyright (c) 2000 Torsten Landschoff <[email protected]>
* Sebastian Krahmer <[email protected]>
*
* License: BSD
*
* 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.
* 3. The names of the authors 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 WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* Modifications: Added PACKET_MMAP support
* Paolo Abeni <[email protected]>
* Added TPACKET_V3 support
* Gabor Tatarka <[email protected]>
*
* based on previous works of:
* Simon Patarin <[email protected]>
* Phil Wood <[email protected]>
*
* Monitor-mode support for mac80211 includes code taken from the iw
* command; the copyright notice for that code is
*
* Copyright (c) 2007, 2008 Johannes Berg
* Copyright (c) 2007 Andy Lutomirski
* Copyright (c) 2007 Mike Kershaw
* Copyright (c) 2008 Gábor Stefanik
*
* 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. 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.
* 3. 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 BY THE AUTHOR ``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.
*/
/*
* Known problems with 2.0[.x] kernels:
*
* - The loopback device gives every packet twice; on 2.2[.x] kernels,
* if we use PF_PACKET, we can filter out the transmitted version
* of the packet by using data in the "sockaddr_ll" returned by
* "recvfrom()", but, on 2.0[.x] kernels, we have to use
* PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a
* "sockaddr_pkt" which doesn't give us enough information to let
* us do that.
*
* - We have to set the interface's IFF_PROMISC flag ourselves, if
* we're to run in promiscuous mode, which means we have to turn
* it off ourselves when we're done; the kernel doesn't keep track
* of how many sockets are listening promiscuously, which means
* it won't get turned off automatically when no sockets are
* listening promiscuously. We catch "pcap_close()" and, for
* interfaces we put into promiscuous mode, take them out of
* promiscuous mode - which isn't necessarily the right thing to
* do, if another socket also requested promiscuous mode between
* the time when we opened the socket and the time when we close
* the socket.
*
* - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()"
* return the amount of data that you could have read, rather than
* the amount that was returned, so we can't just allocate a buffer
* whose size is the snapshot length and pass the snapshot length
* as the byte count, and also pass MSG_TRUNC, so that the return
* value tells us how long the packet was on the wire.
*
* This means that, if we want to get the actual size of the packet,
* so we can return it in the "len" field of the packet header,
* we have to read the entire packet, not just the part that fits
* within the snapshot length, and thus waste CPU time copying data
* from the kernel that our caller won't see.
*
* We have to get the actual size, and supply it in "len", because
* otherwise, the IP dissector in tcpdump, for example, will complain
* about "truncated-ip", as the packet will appear to have been
* shorter, on the wire, than the IP header said it should have been.
*/
#define _GNU_SOURCE
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <limits.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/utsname.h>
#include <sys/mman.h>
#include <linux/if.h>
#include <linux/if_packet.h>
#include <linux/sockios.h>
#include <netinet/in.h>
#include <linux/if_ether.h>
#include <net/if_arp.h>
#include <poll.h>
#include <dirent.h>
#ifdef HAVE_SYS_EVENTFD_H
#include <sys/eventfd.h>
#endif
#include "pcap-int.h"
#include "pcap/sll.h"
#include "pcap/vlan.h"
#include "diag-control.h"
/*
* If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET
* sockets rather than SOCK_PACKET sockets.
*
* To use them, we include <linux/if_packet.h> rather than
* <netpacket/packet.h>; we do so because
*
* some Linux distributions (e.g., Slackware 4.0) have 2.2 or
* later kernels and libc5, and don't provide a <netpacket/packet.h>
* file;
*
* not all versions of glibc2 have a <netpacket/packet.h> file
* that defines stuff needed for some of the 2.4-or-later-kernel
* features, so if the system has a 2.4 or later kernel, we
* still can't use those features.
*
* We're already including a number of other <linux/XXX.h> headers, and
* this code is Linux-specific (no other OS has PF_PACKET sockets as
* a raw packet capture mechanism), so it's not as if you gain any
* useful portability by using <netpacket/packet.h>
*
* XXX - should we just include <linux/if_packet.h> even if PF_PACKET
* isn't defined? It only defines one data structure in 2.0.x, so
* it shouldn't cause any problems.
*/
#ifdef PF_PACKET
# include <linux/if_packet.h>
/*
* On at least some Linux distributions (for example, Red Hat 5.2),
* there's no <netpacket/packet.h> file, but PF_PACKET is defined if
* you include <sys/socket.h>, but <linux/if_packet.h> doesn't define
* any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of
* the PACKET_xxx stuff.
*
* So we check whether PACKET_HOST is defined, and assume that we have
* PF_PACKET sockets only if it is defined.
*/
# ifdef PACKET_HOST
# define HAVE_PF_PACKET_SOCKETS
# ifdef PACKET_AUXDATA
# define HAVE_PACKET_AUXDATA
# endif /* PACKET_AUXDATA */
# endif /* PACKET_HOST */
/* check for memory mapped access avaibility. We assume every needed
* struct is defined if the macro TPACKET_HDRLEN is defined, because it
* uses many ring related structs and macros */
# ifdef PCAP_SUPPORT_PACKET_RING
# ifdef TPACKET_HDRLEN
# define HAVE_PACKET_RING
# ifdef TPACKET3_HDRLEN
# define HAVE_TPACKET3
# endif /* TPACKET3_HDRLEN */
# ifdef TPACKET2_HDRLEN
# define HAVE_TPACKET2
# else /* TPACKET2_HDRLEN */
# define TPACKET_V1 0 /* Old kernel with only V1, so no TPACKET_Vn defined */
# endif /* TPACKET2_HDRLEN */
# endif /* TPACKET_HDRLEN */
# endif /* PCAP_SUPPORT_PACKET_RING */
#endif /* PF_PACKET */
#ifdef SO_ATTACH_FILTER
#include <linux/types.h>
#include <linux/filter.h>
#endif
#ifdef HAVE_LINUX_NET_TSTAMP_H
#include <linux/net_tstamp.h>
#endif
#ifdef HAVE_LINUX_SOCKIOS_H
#include <linux/sockios.h>
#endif
#ifdef HAVE_LINUX_IF_BONDING_H
#include <linux/if_bonding.h>
/*
* The ioctl code to use to check whether a device is a bonding device.
*/
#if defined(SIOCBONDINFOQUERY)
#define BOND_INFO_QUERY_IOCTL SIOCBONDINFOQUERY
#elif defined(BOND_INFO_QUERY_OLD)
#define BOND_INFO_QUERY_IOCTL BOND_INFO_QUERY_OLD
#endif
#endif /* HAVE_LINUX_IF_BONDING_H */
/*
* Got Wireless Extensions?
*/
#ifdef HAVE_LINUX_WIRELESS_H
#include <linux/wireless.h>
#endif /* HAVE_LINUX_WIRELESS_H */
/*
* Got libnl?
*/
#ifdef HAVE_LIBNL
#include <linux/nl80211.h>
#include <netlink/genl/genl.h>
#include <netlink/genl/family.h>
#include <netlink/genl/ctrl.h>
#include <netlink/msg.h>
#include <netlink/attr.h>
#endif /* HAVE_LIBNL */
/*
* Got ethtool support?
*/
#ifdef HAVE_LINUX_ETHTOOL_H
#include <linux/ethtool.h>
#endif
#ifndef HAVE_SOCKLEN_T
typedef int socklen_t;
#endif
#ifndef MSG_TRUNC
/*
* This is being compiled on a system that lacks MSG_TRUNC; define it
* with the value it has in the 2.2 and later kernels, so that, on
* those kernels, when we pass it in the flags argument to "recvfrom()"
* we're passing the right value and thus get the MSG_TRUNC behavior
* we want. (We don't get that behavior on 2.0[.x] kernels, because
* they didn't support MSG_TRUNC.)
*/
#define MSG_TRUNC 0x20
#endif
#ifndef SOL_PACKET
/*
* This is being compiled on a system that lacks SOL_PACKET; define it
* with the value it has in the 2.2 and later kernels, so that we can
* set promiscuous mode in the good modern way rather than the old
* 2.0-kernel crappy way.
*/
#define SOL_PACKET 263
#endif
#define MAX_LINKHEADER_SIZE 256
/*
* When capturing on all interfaces we use this as the buffer size.
* Should be bigger then all MTUs that occur in real life.
* 64kB should be enough for now.
*/
#define BIGGER_THAN_ALL_MTUS (64*1024)
/*
* Private data for capturing on Linux SOCK_PACKET or PF_PACKET sockets.
*/
struct pcap_linux {
u_int packets_read; /* count of packets read with recvfrom() */
long proc_dropped; /* packets reported dropped by /proc/net/dev */
struct pcap_stat stat;
char *device; /* device name */
int filter_in_userland; /* must filter in userland */
int blocks_to_filter_in_userland;
int must_do_on_close; /* stuff we must do when we close */
int timeout; /* timeout for buffering */
int sock_packet; /* using Linux 2.0 compatible interface */
int cooked; /* using SOCK_DGRAM rather than SOCK_RAW */
int ifindex; /* interface index of device we're bound to */
int lo_ifindex; /* interface index of the loopback device */
bpf_u_int32 oldmode; /* mode to restore when turning monitor mode off */
char *mondevice; /* mac80211 monitor device we created */
u_char *mmapbuf; /* memory-mapped region pointer */
size_t mmapbuflen; /* size of region */
int vlan_offset; /* offset at which to insert vlan tags; if -1, don't insert */
u_int tp_version; /* version of tpacket_hdr for mmaped ring */
u_int tp_hdrlen; /* hdrlen of tpacket_hdr for mmaped ring */
u_char *oneshot_buffer; /* buffer for copy of packet */
int poll_timeout; /* timeout to use in poll() */
#ifdef HAVE_TPACKET3
unsigned char *current_packet; /* Current packet within the TPACKET_V3 block. Move to next block if NULL. */
int packets_left; /* Unhandled packets left within the block from previous call to pcap_read_linux_mmap_v3 in case of TPACKET_V3. */
#endif
#ifdef HAVE_SYS_EVENTFD_H
int poll_breakloop_fd; /* fd to an eventfd to break from blocking operations */
#endif
};
/*
* Stuff to do when we close.
*/
#define MUST_CLEAR_PROMISC 0x00000001 /* clear promiscuous mode */
#define MUST_CLEAR_RFMON 0x00000002 /* clear rfmon (monitor) mode */
#define MUST_DELETE_MONIF 0x00000004 /* delete monitor-mode interface */
/*
* Prototypes for internal functions and methods.
*/
static int get_if_flags(const char *, bpf_u_int32 *, char *);
static int is_wifi(int, const char *);
static void map_arphrd_to_dlt(pcap_t *, int, int, const char *, int);
static int pcap_activate_linux(pcap_t *);
static int activate_old(pcap_t *, int);
#ifdef HAVE_PF_PACKET_SOCKETS
static int activate_new(pcap_t *, int);
#ifdef HAVE_PACKET_RING
static int activate_mmap(pcap_t *, int *);
#endif
#endif /* HAVE_PF_PACKET_SOCKETS */
static int pcap_can_set_rfmon_linux(pcap_t *);
static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *);
static int pcap_read_packet(pcap_t *, pcap_handler, u_char *);
static int pcap_inject_linux(pcap_t *, const void *, int);
static int pcap_stats_linux(pcap_t *, struct pcap_stat *);
static int pcap_setfilter_linux(pcap_t *, struct bpf_program *);
static int pcap_setdirection_linux(pcap_t *, pcap_direction_t);
static int pcap_set_datalink_linux(pcap_t *, int);
static void pcap_cleanup_linux(pcap_t *);
/*
* This is what the header structure looks like in a 64-bit kernel;
* we use this, rather than struct tpacket_hdr, if we're using
* TPACKET_V1 in 32-bit code running on a 64-bit kernel.
*/
struct tpacket_hdr_64 {
uint64_t tp_status;
unsigned int tp_len;
unsigned int tp_snaplen;
unsigned short tp_mac;
unsigned short tp_net;
unsigned int tp_sec;
unsigned int tp_usec;
};
/*
* We use this internally as the tpacket version for TPACKET_V1 in
* 32-bit code on a 64-bit kernel.
*/
#define TPACKET_V1_64 99
union thdr {
struct tpacket_hdr *h1;
struct tpacket_hdr_64 *h1_64;
#ifdef HAVE_TPACKET2
struct tpacket2_hdr *h2;
#endif
#ifdef HAVE_TPACKET3
struct tpacket_block_desc *h3;
#endif
void *raw;
};
#ifdef HAVE_PACKET_RING
#define RING_GET_FRAME_AT(h, offset) (((union thdr **)h->buffer)[(offset)])
#define RING_GET_CURRENT_FRAME(h) RING_GET_FRAME_AT(h, h->offset)
static void destroy_ring(pcap_t *handle);
static int create_ring(pcap_t *handle, int *status);
static int prepare_tpacket_socket(pcap_t *handle);
static void pcap_cleanup_linux_mmap(pcap_t *);
static int pcap_read_linux_mmap_v1(pcap_t *, int, pcap_handler , u_char *);
static int pcap_read_linux_mmap_v1_64(pcap_t *, int, pcap_handler , u_char *);
#ifdef HAVE_TPACKET2
static int pcap_read_linux_mmap_v2(pcap_t *, int, pcap_handler , u_char *);
#endif
#ifdef HAVE_TPACKET3
static int pcap_read_linux_mmap_v3(pcap_t *, int, pcap_handler , u_char *);
#endif
static int pcap_setfilter_linux_mmap(pcap_t *, struct bpf_program *);
static int pcap_setnonblock_mmap(pcap_t *p, int nonblock);
static int pcap_getnonblock_mmap(pcap_t *p);
static void pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h,
const u_char *bytes);
#endif
/*
* In pre-3.0 kernels, the tp_vlan_tci field is set to whatever the
* vlan_tci field in the skbuff is. 0 can either mean "not on a VLAN"
* or "on VLAN 0". There is no flag set in the tp_status field to
* distinguish between them.
*
* In 3.0 and later kernels, if there's a VLAN tag present, the tp_vlan_tci
* field is set to the VLAN tag, and the TP_STATUS_VLAN_VALID flag is set
* in the tp_status field, otherwise the tp_vlan_tci field is set to 0 and
* the TP_STATUS_VLAN_VALID flag isn't set in the tp_status field.
*
* With a pre-3.0 kernel, we cannot distinguish between packets with no
* VLAN tag and packets on VLAN 0, so we will mishandle some packets, and
* there's nothing we can do about that.
*
* So, on those systems, which never set the TP_STATUS_VLAN_VALID flag, we
* continue the behavior of earlier libpcaps, wherein we treated packets
* with a VLAN tag of 0 as being packets without a VLAN tag rather than packets
* on VLAN 0. We do this by treating packets with a tp_vlan_tci of 0 and
* with the TP_STATUS_VLAN_VALID flag not set in tp_status as not having
* VLAN tags. This does the right thing on 3.0 and later kernels, and
* continues the old unfixably-imperfect behavior on pre-3.0 kernels.
*
* If TP_STATUS_VLAN_VALID isn't defined, we test it as the 0x10 bit; it
* has that value in 3.0 and later kernels.
*/
#ifdef TP_STATUS_VLAN_VALID
#define VLAN_VALID(hdr, hv) ((hv)->tp_vlan_tci != 0 || ((hdr)->tp_status & TP_STATUS_VLAN_VALID))
#else
/*
* This is being compiled on a system that lacks TP_STATUS_VLAN_VALID,
* so we testwith the value it has in the 3.0 and later kernels, so
* we can test it if we're running on a system that has it. (If we're
* running on a system that doesn't have it, it won't be set in the
* tp_status field, so the tests of it will always fail; that means
* we behave the way we did before we introduced this macro.)
*/
#define VLAN_VALID(hdr, hv) ((hv)->tp_vlan_tci != 0 || ((hdr)->tp_status & 0x10))
#endif
#ifdef TP_STATUS_VLAN_TPID_VALID
# define VLAN_TPID(hdr, hv) (((hv)->tp_vlan_tpid || ((hdr)->tp_status & TP_STATUS_VLAN_TPID_VALID)) ? (hv)->tp_vlan_tpid : ETH_P_8021Q)
#else
# define VLAN_TPID(hdr, hv) ETH_P_8021Q
#endif
/*
* Wrap some ioctl calls
*/
#ifdef HAVE_PF_PACKET_SOCKETS
static int iface_get_id(int fd, const char *device, char *ebuf);
#endif /* HAVE_PF_PACKET_SOCKETS */
static int iface_get_mtu(int fd, const char *device, char *ebuf);
static int iface_get_arptype(int fd, const char *device, char *ebuf);
#ifdef HAVE_PF_PACKET_SOCKETS
static int iface_bind(int fd, int ifindex, char *ebuf, int protocol);
#ifdef IW_MODE_MONITOR
static int has_wext(int sock_fd, const char *device, char *ebuf);
#endif /* IW_MODE_MONITOR */
static int enter_rfmon_mode(pcap_t *handle, int sock_fd,
const char *device);
#endif /* HAVE_PF_PACKET_SOCKETS */
#if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP)
static int iface_ethtool_get_ts_info(const char *device, pcap_t *handle,
char *ebuf);
#endif
#ifdef HAVE_PACKET_RING
static int iface_get_offload(pcap_t *handle);
#endif
static int iface_bind_old(int fd, const char *device, char *ebuf);
#ifdef SO_ATTACH_FILTER
static int fix_program(pcap_t *handle, struct sock_fprog *fcode,
int is_mapped);
static int fix_offset(pcap_t *handle, struct bpf_insn *p);
static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode);
static int reset_kernel_filter(pcap_t *handle);
static struct sock_filter total_insn
= BPF_STMT(BPF_RET | BPF_K, 0);
static struct sock_fprog total_fcode
= { 1, &total_insn };
#endif /* SO_ATTACH_FILTER */
pcap_t *
pcap_create_interface(const char *device, char *ebuf)
{
pcap_t *handle;
handle = pcap_create_common(ebuf, sizeof (struct pcap_linux));
if (handle == NULL)
return NULL;
handle->activate_op = pcap_activate_linux;
handle->can_set_rfmon_op = pcap_can_set_rfmon_linux;
#if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP)
/*
* See what time stamp types we support.
*/
if (iface_ethtool_get_ts_info(device, handle, ebuf) == -1) {
pcap_close(handle);
return NULL;
}
#endif
#if defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS)
/*
* We claim that we support microsecond and nanosecond time
* stamps.
*
* XXX - with adapter-supplied time stamps, can we choose
* microsecond or nanosecond time stamps on arbitrary
* adapters?
*/
handle->tstamp_precision_count = 2;
handle->tstamp_precision_list = malloc(2 * sizeof(u_int));
if (handle->tstamp_precision_list == NULL) {
pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
errno, "malloc");
pcap_close(handle);
return NULL;
}
handle->tstamp_precision_list[0] = PCAP_TSTAMP_PRECISION_MICRO;
handle->tstamp_precision_list[1] = PCAP_TSTAMP_PRECISION_NANO;
#endif /* defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) */
#ifdef HAVE_SYS_EVENTFD_H
struct pcap_linux *handlep = handle->priv;
handlep->poll_breakloop_fd = eventfd(0, EFD_NONBLOCK);
#endif
return handle;
}
#ifdef HAVE_LIBNL
/*
* If interface {if} is a mac80211 driver, the file
* /sys/class/net/{if}/phy80211 is a symlink to
* /sys/class/ieee80211/{phydev}, for some {phydev}.
*
* On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at
* least, has a "wmaster0" device and a "wlan0" device; the
* latter is the one with the IP address. Both show up in
* "tcpdump -D" output. Capturing on the wmaster0 device
* captures with 802.11 headers.
*
* airmon-ng searches through /sys/class/net for devices named
* monN, starting with mon0; as soon as one *doesn't* exist,
* it chooses that as the monitor device name. If the "iw"
* command exists, it does "iw dev {if} interface add {monif}
* type monitor", where {monif} is the monitor device. It
* then (sigh) sleeps .1 second, and then configures the
* device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface
* is a file, it writes {mondev}, without a newline, to that file,
* and again (sigh) sleeps .1 second, and then iwconfig's that
* device into monitor mode and configures it up. Otherwise,
* you can't do monitor mode.
*
* All these devices are "glued" together by having the
* /sys/class/net/{device}/phy80211 links pointing to the same
* place, so, given a wmaster, wlan, or mon device, you can
* find the other devices by looking for devices with
* the same phy80211 link.
*
* To turn monitor mode off, delete the monitor interface,
* either with "iw dev {monif} interface del" or by sending
* {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface
*
* Note: if you try to create a monitor device named "monN", and
* there's already a "monN" device, it fails, as least with
* the netlink interface (which is what iw uses), with a return
* value of -ENFILE. (Return values are negative errnos.) We
* could probably use that to find an unused device.
*
* Yes, you can have multiple monitor devices for a given
* physical device.
*/
/*
* Is this a mac80211 device? If so, fill in the physical device path and
* return 1; if not, return 0. On an error, fill in handle->errbuf and
* return PCAP_ERROR.
*/
static int
get_mac80211_phydev(pcap_t *handle, const char *device, char *phydev_path,
size_t phydev_max_pathlen)
{
char *pathstr;
ssize_t bytes_read;
/*
* Generate the path string for the symlink to the physical device.
*/
if (asprintf(&pathstr, "/sys/class/net/%s/phy80211", device) == -1) {
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: Can't generate path name string for /sys/class/net device",
device);
return PCAP_ERROR;
}
bytes_read = readlink(pathstr, phydev_path, phydev_max_pathlen);
if (bytes_read == -1) {
if (errno == ENOENT || errno == EINVAL) {
/*
* Doesn't exist, or not a symlink; assume that
* means it's not a mac80211 device.
*/
free(pathstr);
return 0;
}
pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "%s: Can't readlink %s", device, pathstr);
free(pathstr);
return PCAP_ERROR;
}
free(pathstr);
phydev_path[bytes_read] = '\0';
return 1;
}
#ifdef HAVE_LIBNL_SOCKETS
#define get_nl_errmsg nl_geterror
#else
/* libnl 2.x compatibility code */
#define nl_sock nl_handle
static inline struct nl_handle *
nl_socket_alloc(void)
{
return nl_handle_alloc();
}
static inline void
nl_socket_free(struct nl_handle *h)
{
nl_handle_destroy(h);
}
#define get_nl_errmsg strerror
static inline int
__genl_ctrl_alloc_cache(struct nl_handle *h, struct nl_cache **cache)
{
struct nl_cache *tmp = genl_ctrl_alloc_cache(h);
if (!tmp)
return -ENOMEM;
*cache = tmp;
return 0;
}
#define genl_ctrl_alloc_cache __genl_ctrl_alloc_cache
#endif /* !HAVE_LIBNL_SOCKETS */
struct nl80211_state {
struct nl_sock *nl_sock;
struct nl_cache *nl_cache;
struct genl_family *nl80211;
};
static int
nl80211_init(pcap_t *handle, struct nl80211_state *state, const char *device)
{
int err;
state->nl_sock = nl_socket_alloc();
if (!state->nl_sock) {
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate netlink handle", device);
return PCAP_ERROR;
}
if (genl_connect(state->nl_sock)) {
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to connect to generic netlink", device);
goto out_handle_destroy;
}
err = genl_ctrl_alloc_cache(state->nl_sock, &state->nl_cache);
if (err < 0) {
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate generic netlink cache: %s",
device, get_nl_errmsg(-err));
goto out_handle_destroy;
}
state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211");
if (!state->nl80211) {
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl80211 not found", device);
goto out_cache_free;
}
return 0;
out_cache_free:
nl_cache_free(state->nl_cache);
out_handle_destroy:
nl_socket_free(state->nl_sock);
return PCAP_ERROR;
}
static void
nl80211_cleanup(struct nl80211_state *state)
{
genl_family_put(state->nl80211);
nl_cache_free(state->nl_cache);
nl_socket_free(state->nl_sock);
}
static int
del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
const char *device, const char *mondevice);
static int
add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
const char *device, const char *mondevice)
{
struct pcap_linux *handlep = handle->priv;
int ifindex;
struct nl_msg *msg;
int err;
ifindex = iface_get_id(sock_fd, device, handle->errbuf);
if (ifindex == -1)
return PCAP_ERROR;
msg = nlmsg_alloc();
if (!msg) {
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate netlink msg", device);
return PCAP_ERROR;
}
genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
0, NL80211_CMD_NEW_INTERFACE, 0);
NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
DIAG_OFF_NARROWING
NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice);
DIAG_ON_NARROWING
NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR);
err = nl_send_auto_complete(state->nl_sock, msg);
if (err < 0) {
#if defined HAVE_LIBNL_NLE
if (err == -NLE_FAILURE) {
#else
if (err == -ENFILE) {
#endif
/*
* Device not available; our caller should just
* keep trying. (libnl 2.x maps ENFILE to
* NLE_FAILURE; it can also map other errors
* to that, but there's not much we can do
* about that.)
*/
nlmsg_free(msg);
return 0;
} else {
/*
* Real failure, not just "that device is not
* available.
*/
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_send_auto_complete failed adding %s interface: %s",
device, mondevice, get_nl_errmsg(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
}
err = nl_wait_for_ack(state->nl_sock);
if (err < 0) {
#if defined HAVE_LIBNL_NLE
if (err == -NLE_FAILURE) {
#else
if (err == -ENFILE) {
#endif
/*
* Device not available; our caller should just
* keep trying. (libnl 2.x maps ENFILE to
* NLE_FAILURE; it can also map other errors
* to that, but there's not much we can do
* about that.)
*/
nlmsg_free(msg);
return 0;
} else {
/*
* Real failure, not just "that device is not
* available.
*/
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_wait_for_ack failed adding %s interface: %s",
device, mondevice, get_nl_errmsg(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
}
/*
* Success.
*/
nlmsg_free(msg);
/*
* Try to remember the monitor device.
*/
handlep->mondevice = strdup(mondevice);
if (handlep->mondevice == NULL) {
pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "strdup");
/*
* Get rid of the monitor device.
*/
del_mon_if(handle, sock_fd, state, device, mondevice);
return PCAP_ERROR;
}
return 1;
nla_put_failure:
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_put failed adding %s interface",
device, mondevice);
nlmsg_free(msg);
return PCAP_ERROR;
}
static int
del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
const char *device, const char *mondevice)
{
int ifindex;
struct nl_msg *msg;
int err;
ifindex = iface_get_id(sock_fd, mondevice, handle->errbuf);
if (ifindex == -1)
return PCAP_ERROR;
msg = nlmsg_alloc();
if (!msg) {
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate netlink msg", device);
return PCAP_ERROR;
}
genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
0, NL80211_CMD_DEL_INTERFACE, 0);
NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
err = nl_send_auto_complete(state->nl_sock, msg);
if (err < 0) {
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_send_auto_complete failed deleting %s interface: %s",
device, mondevice, get_nl_errmsg(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
err = nl_wait_for_ack(state->nl_sock);
if (err < 0) {
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_wait_for_ack failed adding %s interface: %s",
device, mondevice, get_nl_errmsg(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
/*
* Success.
*/
nlmsg_free(msg);
return 1;
nla_put_failure:
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_put failed deleting %s interface",
device, mondevice);
nlmsg_free(msg);
return PCAP_ERROR;
}
static int
enter_rfmon_mode_mac80211(pcap_t *handle, int sock_fd, const char *device)
{
struct pcap_linux *handlep = handle->priv;
int ret;
char phydev_path[PATH_MAX+1];
struct nl80211_state nlstate;
struct ifreq ifr;
u_int n;
/*
* Is this a mac80211 device?
*/
ret = get_mac80211_phydev(handle, device, phydev_path, PATH_MAX);
if (ret < 0)
return ret; /* error */
if (ret == 0)
return 0; /* no error, but not mac80211 device */
/*
* XXX - is this already a monN device?
* If so, we're done.
* Is that determined by old Wireless Extensions ioctls?
*/
/*
* OK, it's apparently a mac80211 device.
* Try to find an unused monN device for it.
*/
ret = nl80211_init(handle, &nlstate, device);
if (ret != 0)
return ret;
for (n = 0; n < UINT_MAX; n++) {
/*
* Try mon{n}.
*/
char mondevice[3+10+1]; /* mon{UINT_MAX}\0 */
pcap_snprintf(mondevice, sizeof mondevice, "mon%u", n);
ret = add_mon_if(handle, sock_fd, &nlstate, device, mondevice);
if (ret == 1) {
/*
* Success. We don't clean up the libnl state
* yet, as we'll be using it later.
*/
goto added;
}
if (ret < 0) {
/*
* Hard failure. Just return ret; handle->errbuf
* has already been set.
*/
nl80211_cleanup(&nlstate);
return ret;
}
}
pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: No free monN interfaces", device);
nl80211_cleanup(&nlstate);
return PCAP_ERROR;
added:
#if 0
/*
* Sleep for .1 seconds.
*/
delay.tv_sec = 0;
delay.tv_nsec = 500000000;
nanosleep(&delay, NULL);
#endif
/*
* If we haven't already done so, arrange to have
* "pcap_close_all()" called when we exit.
*/
if (!pcap_do_addexit(handle)) {
/*
* "atexit()" failed; don't put the interface
* in rfmon mode, just give up.
*/
del_mon_if(handle, sock_fd, &nlstate, device,
handlep->mondevice);
nl80211_cleanup(&nlstate);
return PCAP_ERROR;
}
/*
* Now configure the monitor interface up.
*/
memset(&ifr, 0, sizeof(ifr));
pcap_strlcpy(ifr.ifr_name, handlep->mondevice, sizeof(ifr.ifr_name));
if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) {
pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "%s: Can't get flags for %s", device,