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dumpcap.c
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/* dumpcap.c
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include <config.h>
#define WS_LOG_DOMAIN LOG_DOMAIN_CAPCHILD
#include <stdio.h>
#include <stdlib.h> /* for exit() */
#include <glib.h>
#include <string.h>
#include <sys/types.h>
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#include <wsutil/ws_getopt.h>
#if defined(__APPLE__) && defined(__LP64__)
#include <sys/utsname.h>
#endif
#include <signal.h>
#include <errno.h>
#include <wsutil/cmdarg_err.h>
#include <wsutil/strtoi.h>
#include <cli_main.h>
#include <wsutil/version_info.h>
#include <wsutil/socket.h>
#include <wsutil/wslog.h>
#include <wsutil/file_util.h>
#ifdef HAVE_LIBCAP
# include <sys/prctl.h>
# include <sys/capability.h>
#endif
#include "ringbuffer.h"
#include "capture/capture_ifinfo.h"
#include "capture/capture-pcap-util.h"
#include "capture/capture-pcap-util-int.h"
#ifdef _WIN32
#include "capture/capture-wpcap.h"
#endif /* _WIN32 */
#include "writecap/pcapio.h"
#ifndef _WIN32
#include <sys/un.h>
#endif
#include <wsutil/clopts_common.h>
#include <wsutil/privileges.h>
#include "sync_pipe.h"
#include "capture_opts.h"
#include <capture/capture_session.h>
#include <capture/capture_sync.h>
#include "wsutil/tempfile.h"
#include "wsutil/file_util.h"
#include "wsutil/cpu_info.h"
#include "wsutil/os_version_info.h"
#include "wsutil/str_util.h"
#include "wsutil/inet_addr.h"
#include "wsutil/time_util.h"
#include "wsutil/please_report_bug.h"
#include "wsutil/glib-compat.h"
#include <wsutil/ws_assert.h>
#include "capture/ws80211_utils.h"
#include "extcap.h"
/*
* Get information about libpcap format from "wiretap/libpcap.h".
* Get information about pcapng format from "wiretap/pcapng_module.h".
* XXX - can we just use pcap_open_offline() to read the pipe?
*/
#include "wiretap/libpcap.h"
#include "wiretap/pcapng_module.h"
#include "wiretap/pcapng.h"
/*
* Define these for extra logging messages at INFO and below. Note
* that when dumpcap is spawned as a child process, logs are sent
* to the parent via the sync pipe.
*/
/**#define DEBUG_DUMPCAP**/ /* Logs INFO and below messages normally */
/**#define DEBUG_CHILD_DUMPCAP**/ /* Writes INFO and below logs to file */
#ifdef _WIN32
#include "wsutil/win32-utils.h"
#ifdef DEBUG_DUMPCAP
#include <conio.h> /* _getch() */
#endif
#endif
#ifdef DEBUG_CHILD_DUMPCAP
FILE *debug_log; /* for logging debug messages to */
/* a file if DEBUG_CHILD_DUMPCAP */
/* is defined */
#ifdef DEBUG_DUMPCAP
#include <stdarg.h> /* va_copy */
#endif
#endif
static GAsyncQueue *pcap_queue;
static gint64 pcap_queue_bytes;
static gint64 pcap_queue_packets;
static gint64 pcap_queue_byte_limit = 0;
static gint64 pcap_queue_packet_limit = 0;
static gboolean capture_child = FALSE; /* FALSE: standalone call, TRUE: this is an Wireshark capture child */
static const char *report_capture_filename = NULL; /* capture child file name */
#ifdef _WIN32
static gchar *sig_pipe_name = NULL;
static HANDLE sig_pipe_handle = NULL;
static gboolean signal_pipe_check_running(void);
#endif
#ifdef ENABLE_ASAN
/* This has public visibility so that if compiled with shared libasan (the
* gcc default) function interposition occurs.
*/
WS_DLL_PUBLIC int
__lsan_is_turned_off(void)
{
/* If we're in capture child mode, don't run a LSan report and
* send it to stderr, because it isn't properly formatted for
* the sync pipe.
* We could, if debugging variables are set, send the reports
* elsewhere instead, by calling __sanitizer_set_report_path()
* or __sanitizer_set_report_fd()
*/
if (capture_child) {
return 1;
}
#ifdef HAVE_LIBCAP
/* LSan dies with a fatal error without explanation if it can't ptrace.
* Normally, the "dumpable" attribute (which also controls ptracing)
* is set to 1 (SUID_DUMP_USER, process is dumpable.) However, it is
* reset to the current value in /proc/sys/fs/suid_dumpable in the
* following circumstances: euid/egid changes, fsuid/fsgid changes,
* execve of a setuid or setgid program that changes the euid or egid,
* execve of a program with capabilities exceeding those already
* permitted for the process.
*
* Unless we're running as root, one of those applies to dumpcap.
*
* The default value of /proc/sys/fs/suid_dumpable is 0, SUID_DUMP_DISABLE.
* In such a case, LeakSanitizer temporarily sets the value to 1 to
* allow ptracing, and then sets it back to 0.
*
* Another possible value, used by Ubuntu, Fedora, etc., is 2,
* which creates dumps readable by root only. For security reasons,
* unprivileged programs are not allowed to change the value to 2.
* (See https://nvd.nist.gov/vuln/detail/CVE-2006-2451 )
*
* LSan does not check for the value 2 and change dumpable to 1 in that
* case, possibly because if it did it could not change it back to 2
* and would have to either leave the process dumpable or change it to 0.
*
* The usual way to control the family of sanitizers is through environment
* variables. However, complicating things, changing the dumpable attribute
* to 0 or 2 changes the ownership of files in /proc/[pid] (including
* /proc/self ) to root:root, in particular /proc/[pid]/environ, and so
* ASAN_OPTIONS=detect_leaks=0 has no effect. (Unless the process has
* CAP_SYS_PTRACE, which allows tracing of any process, but that's also
* a security risk and we'll have dropped that with other privileges.)
*
* So if prctl(PR_GET_DUMPABLE) returns 2, we know that the process will
* die with a fatal error if it attempts to run LSan, so don't.
*
* See proc(5), prctl(2), ptrace(2), and
* https://github.com/google/sanitizers/issues/1306
* https://github.com/llvm/llvm-project/issues/55944
*/
if (prctl(PR_GET_DUMPABLE) == 2) {
ws_debug("Not running LeakSanitizer because /proc/sys/fs/suid_dumpable is 2");
return 1;
}
#endif
return 0;
}
WS_DLL_PUBLIC const char*
__asan_default_options(void)
{
/* By default don't override our exit code if there's a leak or error.
* We particularly don't want to do this if running as a capture child,
* because capture/capture_sync doesn't expect the ASan exit codes.
*/
return "exitcode=0";
}
#endif
#ifdef SIGINFO
static gboolean infodelay; /* if TRUE, don't print capture info in SIGINFO handler */
static gboolean infoprint; /* if TRUE, print capture info after clearing infodelay */
#endif /* SIGINFO */
/** Stop a low-level capture (stops the capture child). */
static void capture_loop_stop(void);
/** Close a pipe, or socket if \a from_socket is TRUE */
static void cap_pipe_close(int pipe_fd, gboolean from_socket);
#if defined (__linux__)
/* whatever the deal with pcap_breakloop, linux doesn't support timeouts
* in pcap_dispatch(); on the other hand, select() works just fine there.
* Hence we use a select for that come what may.
*
* XXX - with TPACKET_V1 and TPACKET_V2, it currently uses select()
* internally, and, with TPACKET_V3, once that's supported, it'll
* support timeouts, at least as I understand the way the code works.
*/
#define MUST_DO_SELECT
#endif
/** init the capture filter */
typedef enum {
INITFILTER_NO_ERROR,
INITFILTER_BAD_FILTER,
INITFILTER_OTHER_ERROR
} initfilter_status_t;
typedef enum {
STATE_EXPECT_REC_HDR,
STATE_READ_REC_HDR,
STATE_EXPECT_DATA,
STATE_READ_DATA
} cap_pipe_state_t;
typedef enum {
PIPOK,
PIPEOF,
PIPERR,
PIPNEXIST
} cap_pipe_err_t;
typedef struct _pcap_pipe_info {
gboolean byte_swapped; /**< TRUE if data in the pipe is byte swapped. */
struct pcap_hdr hdr; /**< Pcap header when capturing from a pipe */
struct pcaprec_modified_hdr rechdr; /**< Pcap record header when capturing from a pipe */
} pcap_pipe_info_t;
typedef struct _pcapng_pipe_info {
pcapng_block_header_t bh; /**< Pcapng general block header when capturing from a pipe */
GArray *src_iface_to_global; /**< Int array mapping local IDB numbers to global_ld.interface_data */
} pcapng_pipe_info_t;
struct _loop_data; /* forward declaration so we can use it in the cap_pipe_dispatch function pointer */
/*
* A source of packets from which we're capturing.
*/
typedef struct _capture_src {
guint32 received;
guint32 dropped;
guint32 flushed;
pcap_t *pcap_h;
#ifdef MUST_DO_SELECT
int pcap_fd; /**< pcap file descriptor */
#endif
gboolean pcap_err;
guint interface_id;
guint idb_id; /**< If from_pcapng is false, the output IDB interface ID. Otherwise the mapping in src_iface_to_global is used. */
GThread *tid;
int snaplen;
int linktype;
gboolean ts_nsec; /**< TRUE if we're using nanosecond precision. */
/**< capture pipe (unix only "input file") */
gboolean from_cap_pipe; /**< TRUE if we are capturing data from a capture pipe */
gboolean from_cap_socket; /**< TRUE if we're capturing from socket */
gboolean from_pcapng; /**< TRUE if we're capturing from pcapng format */
union {
pcap_pipe_info_t pcap; /**< Pcap info when capturing from a pipe */
pcapng_pipe_info_t pcapng; /**< Pcapng info when capturing from a pipe */
} cap_pipe_info;
#ifdef _WIN32
HANDLE cap_pipe_h; /**< The handle of the capture pipe */
#endif
int cap_pipe_fd; /**< the file descriptor of the capture pipe */
gboolean cap_pipe_modified; /**< TRUE if data in the pipe uses modified pcap headers */
char * cap_pipe_databuf; /**< Pointer to the data buffer we've allocated */
size_t cap_pipe_databuf_size; /**< Current size of the data buffer */
guint cap_pipe_max_pkt_size; /**< Maximum packet size allowed */
#if defined(_WIN32)
char * cap_pipe_buf; /**< Pointer to the buffer we read into */
DWORD cap_pipe_bytes_to_read; /**< Used by cap_pipe_dispatch */
DWORD cap_pipe_bytes_read; /**< Used by cap_pipe_dispatch */
#else
size_t cap_pipe_bytes_to_read; /**< Used by cap_pipe_dispatch */
size_t cap_pipe_bytes_read; /**< Used by cap_pipe_dispatch */
#endif
int (*cap_pipe_dispatch)(struct _loop_data *, struct _capture_src *, char *, size_t);
cap_pipe_state_t cap_pipe_state;
cap_pipe_err_t cap_pipe_err;
#if defined(_WIN32)
GMutex *cap_pipe_read_mtx;
GAsyncQueue *cap_pipe_pending_q, *cap_pipe_done_q;
#endif
} capture_src;
typedef struct _saved_idb {
gboolean deleted;
guint interface_id; /* capture_src->interface_id for the associated SHB */
guint8 *idb; /* If non-NULL, IDB read from capture_src. This is an interface specified on the command line otherwise. */
guint idb_len;
} saved_idb_t;
/*
* Global capture loop state.
*/
typedef struct _loop_data {
/* common */
gboolean go; /**< TRUE as long as we're supposed to keep capturing */
int err; /**< if non-zero, error seen while capturing */
gint packets_captured; /**< Number of packets we have already captured */
guint inpkts_to_sync_pipe; /**< Packets not already send out to the sync_pipe */
#ifdef SIGINFO
gboolean report_packet_count; /**< Set by SIGINFO handler; print packet count */
#endif
GArray *pcaps; /**< Array of capture_src's on which we're capturing */
gboolean pcapng_passthrough; /**< We have one source and it's pcapng. Pass its SHB and IDBs through. */
guint8 *saved_shb; /**< SHB to write when we have one pcapng input */
GArray *saved_idbs; /**< Array of saved_idb_t, written when we have a new section or output file. */
GRWLock saved_shb_idb_lock; /**< Saved IDB RW mutex */
/* output file(s) */
FILE *pdh;
int save_file_fd;
char *io_buffer; /**< Our IO buffer if we increase the size from the standard size */
guint64 bytes_written; /**< Bytes written for the current file. */
/* autostop conditions */
int packets_written; /**< Packets written for the current file. */
int file_count;
/* ring buffer conditions */
GTimer *file_duration_timer;
time_t next_interval_time;
int interval_s;
} loop_data;
typedef struct _pcap_queue_element {
capture_src *pcap_src;
union {
struct pcap_pkthdr phdr;
pcapng_block_header_t bh;
} u;
u_char *pd;
} pcap_queue_element;
/*
* This needs to be static, so that the SIGINT handler can clear the "go"
* flag and for saved_shb_idb_lock.
*/
static loop_data global_ld;
/*
* Timeout, in milliseconds, for reads from the stream of captured packets
* from a capture device.
*
* A bug in Mac OS X 10.6 and 10.6.1 causes calls to pcap_open_live(), in
* 64-bit applications, with sub-second timeouts not to work. The bug is
* fixed in 10.6.2, re-broken in 10.6.3, and again fixed in 10.6.5.
*/
#if defined(__APPLE__) && defined(__LP64__)
static gboolean need_timeout_workaround;
#define CAP_READ_TIMEOUT (need_timeout_workaround ? 1000 : 250)
#else
#define CAP_READ_TIMEOUT 250
#endif
/*
* Timeout, in microseconds, for reads from the stream of captured packets
* from a pipe. Pipes don't have the same problem that BPF devices do
* in Mac OS X 10.6, 10.6.1, 10.6.3, and 10.6.4, so we always use a timeout
* of 250ms, i.e. the same value as CAP_READ_TIMEOUT when not on one
* of the offending versions of Snow Leopard.
*
* On Windows this value is converted to milliseconds and passed to
* WaitForSingleObject. If it's less than 1000 WaitForSingleObject
* will return immediately.
*/
#if defined(_WIN32)
#define PIPE_READ_TIMEOUT 100000
#else
#define PIPE_READ_TIMEOUT 250000
#endif
#define WRITER_THREAD_TIMEOUT 100000 /* usecs */
static void
dumpcap_log_writer(const char *domain, enum ws_log_level level,
const char *file, long line, const char *func,
const char *fatal_msg, ws_log_manifest_t *mft,
const char *user_format, va_list user_ap,
void *user_data);
/* capture related options */
static capture_options global_capture_opts;
static GPtrArray *capture_comments = NULL;
static gboolean quiet = FALSE;
static gboolean use_threads = FALSE;
static guint64 start_time;
static void capture_loop_write_packet_cb(u_char *pcap_src_p, const struct pcap_pkthdr *phdr,
const u_char *pd);
static void capture_loop_queue_packet_cb(u_char *pcap_src_p, const struct pcap_pkthdr *phdr,
const u_char *pd);
static void capture_loop_write_pcapng_cb(capture_src *pcap_src, const pcapng_block_header_t *bh, u_char *pd);
static void capture_loop_queue_pcapng_cb(capture_src *pcap_src, const pcapng_block_header_t *bh, u_char *pd);
static void capture_loop_get_errmsg(char *errmsg, size_t errmsglen,
char *secondary_errmsg,
size_t secondary_errmsglen,
const char *fname, int err,
gboolean is_close);
WS_NORETURN static void exit_main(int err);
static void report_new_capture_file(const char *filename);
static void report_packet_count(unsigned int packet_count);
static void report_packet_drops(guint32 received, guint32 pcap_drops, guint32 drops, guint32 flushed, guint32 ps_ifdrop, gchar *name);
static void report_capture_error(const char *error_msg, const char *secondary_error_msg);
static void report_cfilter_error(capture_options *capture_opts, guint i, const char *errmsg);
#define MSG_MAX_LENGTH 4096
static void
print_usage(FILE *output)
{
fprintf(output, "\nUsage: dumpcap [options] ...\n");
fprintf(output, "\n");
fprintf(output, "Capture interface:\n");
fprintf(output, " -i <interface>, --interface <interface>\n");
fprintf(output, " name or idx of interface (def: first non-loopback),\n"
" or for remote capturing, use one of these formats:\n"
" rpcap://<host>/<interface>\n"
" TCP@<host>:<port>\n");
fprintf(output, " --ifname <name> name to use in the capture file for a pipe from which\n");
fprintf(output, " we're capturing\n");
fprintf(output, " --ifdescr <description>\n");
fprintf(output, " description to use in the capture file for a pipe\n");
fprintf(output, " from which we're capturing\n");
fprintf(output, " -f <capture filter> packet filter in libpcap filter syntax\n");
fprintf(output, " -s <snaplen>, --snapshot-length <snaplen>\n");
#ifdef HAVE_PCAP_CREATE
fprintf(output, " packet snapshot length (def: appropriate maximum)\n");
#else
fprintf(output, " packet snapshot length (def: %u)\n", WTAP_MAX_PACKET_SIZE_STANDARD);
#endif
fprintf(output, " -p, --no-promiscuous-mode\n");
fprintf(output, " don't capture in promiscuous mode\n");
#ifdef HAVE_PCAP_CREATE
fprintf(output, " -I, --monitor-mode capture in monitor mode, if available\n");
#endif
#ifdef CAN_SET_CAPTURE_BUFFER_SIZE
fprintf(output, " -B <buffer size>, --buffer-size <buffer size>\n");
fprintf(output, " size of kernel buffer in MiB (def: %dMiB)\n", DEFAULT_CAPTURE_BUFFER_SIZE);
#endif
fprintf(output, " -y <link type>, --linktype <link type>\n");
fprintf(output, " link layer type (def: first appropriate)\n");
fprintf(output, " --time-stamp-type <type> timestamp method for interface\n");
fprintf(output, " -D, --list-interfaces print list of interfaces and exit\n");
fprintf(output, " -L, --list-data-link-types\n");
fprintf(output, " print list of link-layer types of iface and exit\n");
fprintf(output, " --list-time-stamp-types print list of timestamp types for iface and exit\n");
fprintf(output, " --update-interval interval between updates with new packets (def: %dms)\n", DEFAULT_UPDATE_INTERVAL);
fprintf(output, " -d print generated BPF code for capture filter\n");
fprintf(output, " -k <freq>,[<type>],[<center_freq1>],[<center_freq2>]\n");
fprintf(output, " set channel on wifi interface\n");
fprintf(output, " -S print statistics for each interface once per second\n");
fprintf(output, " -M for -D, -L, and -S, produce machine-readable output\n");
fprintf(output, "\n");
#ifdef HAVE_PCAP_REMOTE
fprintf(output, "RPCAP options:\n");
fprintf(output, " -r don't ignore own RPCAP traffic in capture\n");
fprintf(output, " -u use UDP for RPCAP data transfer\n");
fprintf(output, " -A <user>:<password> use RPCAP password authentication\n");
#ifdef HAVE_PCAP_SETSAMPLING
fprintf(output, " -m <sampling type> use packet sampling\n");
fprintf(output, " count:NUM - capture one packet of every NUM\n");
fprintf(output, " timer:NUM - capture no more than 1 packet in NUM ms\n");
#endif
#endif
fprintf(output, "Stop conditions:\n");
fprintf(output, " -c <packet count> stop after n packets (def: infinite)\n");
fprintf(output, " -a <autostop cond.> ..., --autostop <autostop cond.> ...\n");
fprintf(output, " duration:NUM - stop after NUM seconds\n");
fprintf(output, " filesize:NUM - stop this file after NUM kB\n");
fprintf(output, " files:NUM - stop after NUM files\n");
fprintf(output, " packets:NUM - stop after NUM packets\n");
/*fprintf(output, "\n");*/
fprintf(output, "Output (files):\n");
fprintf(output, " -w <filename> name of file to save (def: tempfile)\n");
fprintf(output, " -g enable group read access on the output file(s)\n");
fprintf(output, " -b <ringbuffer opt.> ..., --ring-buffer <ringbuffer opt.>\n");
fprintf(output, " duration:NUM - switch to next file after NUM secs\n");
fprintf(output, " filesize:NUM - switch to next file after NUM kB\n");
fprintf(output, " files:NUM - ringbuffer: replace after NUM files\n");
fprintf(output, " packets:NUM - ringbuffer: replace after NUM packets\n");
fprintf(output, " interval:NUM - switch to next file when the time is\n");
fprintf(output, " an exact multiple of NUM secs\n");
fprintf(output, " printname:FILE - print filename to FILE when written\n");
fprintf(output, " (can use 'stdout' or 'stderr')\n");
fprintf(output, " -n use pcapng format instead of pcap (default)\n");
fprintf(output, " -P use libpcap format instead of pcapng\n");
fprintf(output, " --capture-comment <comment>\n");
fprintf(output, " add a capture comment to the output file\n");
fprintf(output, " (only for pcapng)\n");
fprintf(output, " --temp-dir <directory> write temporary files to this directory\n");
fprintf(output, " (default: %s)\n", g_get_tmp_dir());
fprintf(output, "\n");
ws_log_print_usage(output);
fprintf(output, "\n");
fprintf(output, "Miscellaneous:\n");
fprintf(output, " -N <packet_limit> maximum number of packets buffered within dumpcap\n");
fprintf(output, " -C <byte_limit> maximum number of bytes used for buffering packets\n");
fprintf(output, " within dumpcap\n");
fprintf(output, " -t use a separate thread per interface\n");
fprintf(output, " -q don't report packet capture counts\n");
fprintf(output, " -v, --version print version information and exit\n");
fprintf(output, " -h, --help display this help and exit\n");
fprintf(output, "\n");
#ifdef __linux__
fprintf(output, "Dumpcap can benefit from an enabled BPF JIT compiler if available.\n");
fprintf(output, "You might want to enable it by executing:\n");
fprintf(output, " \"echo 1 > /proc/sys/net/core/bpf_jit_enable\"\n");
fprintf(output, "Note that this can make your system less secure!\n");
fprintf(output, "\n");
#endif
fprintf(output, "Example: dumpcap -i eth0 -a duration:60 -w output.pcapng\n");
fprintf(output, "\"Capture packets from interface eth0 until 60s passed into output.pcapng\"\n");
fprintf(output, "\n");
fprintf(output, "Use Ctrl-C to stop capturing at any time.\n");
}
/*
* Report an error in command-line arguments.
* If we're a capture child, send a message back to the parent, otherwise
* just print it.
*/
static void
dumpcap_cmdarg_err(const char *fmt, va_list ap)
{
if (capture_child) {
gchar *msg;
/* Generate a 'special format' message back to parent */
msg = ws_strdup_vprintf(fmt, ap);
sync_pipe_write_errmsgs_to_parent(2, msg, "");
g_free(msg);
} else {
fprintf(stderr, "dumpcap: ");
vfprintf(stderr, fmt, ap);
fprintf(stderr, "\n");
}
}
/*
* Report additional information for an error in command-line arguments.
* If we're a capture child, send a message back to the parent, otherwise
* just print it.
*/
static void
dumpcap_cmdarg_err_cont(const char *fmt, va_list ap)
{
if (capture_child) {
gchar *msg;
msg = ws_strdup_vprintf(fmt, ap);
sync_pipe_write_errmsgs_to_parent(2, msg, "");
g_free(msg);
} else {
vfprintf(stderr, fmt, ap);
fprintf(stderr, "\n");
}
}
#ifdef HAVE_LIBCAP
static void
#if 0 /* Set to enable capability debugging */
/* see 'man cap_to_text()' for explanation of output */
/* '=' means 'all= ' ie: no capabilities */
/* '=ip' means 'all=ip' ie: all capabilities are permissible and inheritable */
/* .... */
print_caps(const char *pfx) {
cap_t caps = cap_get_proc();
ws_debug("%s: EUID: %d Capabilities: %s", pfx, geteuid(), cap_to_text(caps, NULL));
cap_free(caps);
}
#else
print_caps(const char *pfx _U_) {
}
#endif
static void
relinquish_all_capabilities(void)
{
/* Drop any and all capabilities this process may have. */
/* Allowed whether or not process has any privileges. */
cap_t caps = cap_init(); /* all capabilities initialized to off */
print_caps("Pre-clear");
if (cap_set_proc(caps)) {
cmdarg_err("cap_set_proc() fail return: %s", g_strerror(errno));
}
print_caps("Post-clear");
cap_free(caps);
}
#endif
/*
* Platform-dependent suggestions for fixing permissions.
*/
#ifdef HAVE_LIBCAP
#define LIBCAP_PERMISSIONS_SUGGESTION \
"\n\n" \
"If you did not install Wireshark from a package, ensure that Dumpcap " \
"has the needed CAP_NET_RAW and CAP_NET_ADMIN capabilities by running " \
"\n\n" \
" sudo setcap cap_net_raw,cap_net_admin=ep {path/to/}dumpcap" \
"\n\n" \
"and then restarting Wireshark."
#else
#define LIBCAP_PERMISSIONS_SUGGESTION
#endif
#if defined(__linux__)
#define PLATFORM_PERMISSIONS_SUGGESTION \
"\n\n" \
"On Debian and Debian derivatives such as Ubuntu, if you have " \
"installed Wireshark from a package, try running" \
"\n\n" \
" sudo dpkg-reconfigure wireshark-common" \
"\n\n" \
"selecting \"<Yes>\" in response to the question" \
"\n\n" \
" Should non-superusers be able to capture packets?" \
"\n\n" \
"adding yourself to the \"wireshark\" group by running" \
"\n\n" \
" sudo usermod -a -G wireshark {your username}" \
"\n\n" \
"and then logging out and logging back in again." \
LIBCAP_PERMISSIONS_SUGGESTION
#elif defined(__APPLE__)
#define PLATFORM_PERMISSIONS_SUGGESTION \
"\n\n" \
"If you installed Wireshark using the package from wireshark.org, " \
"close this dialog and click on the \"installing ChmodBPF\" link in " \
"\"You can fix this by installing ChmodBPF.\" on the main screen, " \
"and then complete the installation procedure."
#else
#define PLATFORM_PERMISSIONS_SUGGESTION
#endif
static const char *
get_pcap_failure_secondary_error_message(cap_device_open_status open_status,
const char *open_status_str)
{
#ifdef _WIN32
/*
* On Windows, first make sure they *have* Npcap installed.
*/
if (!has_wpcap) {
return
"In order to capture packets, Npcap or WinPcap must be installed. See\n"
"\n"
" https://npcap.com/\n"
"\n"
"for a downloadable version of Npcap and for instructions on how to\n"
"install it.";
}
#endif
/*
* OK, now just return a largely platform-independent error that might
* have platform-specific suggestions at the end (for example, suggestions
* for how to get permission to capture).
*/
switch (open_status) {
case CAP_DEVICE_OPEN_ERROR_NO_SUCH_DEVICE:
case CAP_DEVICE_OPEN_ERROR_RFMON_NOTSUP:
case CAP_DEVICE_OPEN_ERROR_IFACE_NOT_UP:
/*
* Not clear what suggestions to make for these cases.
*/
return "";
case CAP_DEVICE_OPEN_ERROR_PERM_DENIED:
case CAP_DEVICE_OPEN_ERROR_PROMISC_PERM_DENIED:
/*
* This is a permissions error, so no need to specify any other
* warnings.
*/
return
"Please check to make sure you have sufficient permissions."
PLATFORM_PERMISSIONS_SUGGESTION;
break;
case CAP_DEVICE_OPEN_ERROR_OTHER:
case CAP_DEVICE_OPEN_ERROR_GENERIC:
{
/*
* We don't know what kind of error it is. See if there's a hint
* in the error string; if not, throw all generic suggestions at
* the user.
*/
static const char promisc_failed[] =
"failed to set hardware filter to promiscuous mode";
#if defined(__linux__)
static const char af_notsup[] =
"socket: Address family not supported by protocol";
#endif
/*
* Check for some text that pops up in some errors.
*/
if (strncmp(open_status_str, promisc_failed, sizeof promisc_failed - 1) == 0) {
/*
* The error string begins with the error produced by WinPcap
* and Npcap if attempting to set promiscuous mode fails.
* (Note that this string could have a specific error message
* from an NDIS error after the initial part, so we do a prefix
* check rather than an exact match check.)
*
* Suggest that the user turn off promiscuous mode on that
* device.
*/
return
"Please turn off promiscuous mode for this device";
#if defined(__linux__)
} else if (strcmp(open_status_str, af_notsup) == 0) {
/*
* The error string is the message provided by libpcap on
* Linux if an attempt to open a PF_PACKET socket failed
* with EAFNOSUPPORT. This probably means that either 1)
* the kernel doesn't have PF_PACKET support configured in
* or 2) this is a Flatpak version of Wireshark that's been
* sandboxed in a way that disallows opening PF_PACKET
* sockets.
*
* Suggest that the user find some other package of
* Wireshark if they want to capture traffic and are
* running a Flatpak of Wireshark or that they configure
* PF_PACKET support back in if it's configured out.
*/
return
"If you are running Wireshark from a Flatpak package, "
"it does not support packet capture; you will need "
"to run a different version of Wireshark in order "
"to capture traffic.\n"
"\n"
"Otherwise, if your machine is running a kernel that "
"was not configured with CONFIG_PACKET, that kernel "
"does not support packet capture; you will need to "
"use a kernel configured with CONFIG_PACKET.";
#endif
} else {
/*
* No. Was this a "generic" error from pcap_open_live()
* or pcap_open(), in which case it might be a permissions
* error?
*/
if (open_status == CAP_DEVICE_OPEN_ERROR_GENERIC) {
return
"Please check to make sure you have sufficient permissions, and that you have "
"the proper interface or pipe specified."
PLATFORM_PERMISSIONS_SUGGESTION;
} else {
/*
* This is not a permissions error, so no need to suggest
* checking permissions.
*/
return
"Please check that you have the proper interface or pipe specified.";
}
}
}
break;
default:
/*
* This is not a permissions error, so no need to suggest
* checking permissions.
*/
return
"Please check that you have the proper interface or pipe specified.";
break;
}
}
static void
get_capture_device_open_failure_messages(cap_device_open_status open_status,
const char *open_status_str,
const char *iface,
char *errmsg, size_t errmsg_len,
char *secondary_errmsg,
size_t secondary_errmsg_len)
{
switch (open_status) {
case CAP_DEVICE_OPEN_ERROR_NO_SUCH_DEVICE:
snprintf(errmsg, errmsg_len,
"There is no device named \"%s\".\n(%s)",
iface, open_status_str);
break;
case CAP_DEVICE_OPEN_ERROR_RFMON_NOTSUP:
snprintf(errmsg, errmsg_len,
"Capturing in monitor mode is not supported on device \"%s\".\n(%s)",
iface, open_status_str);
break;
case CAP_DEVICE_OPEN_ERROR_PERM_DENIED:
snprintf(errmsg, errmsg_len,
"You do not have permission to capture on device \"%s\".\n(%s)",
iface, open_status_str);
break;
case CAP_DEVICE_OPEN_ERROR_IFACE_NOT_UP:
snprintf(errmsg, errmsg_len,
"Device \"%s\" is not up.\n(%s)",
iface, open_status_str);
break;
case CAP_DEVICE_OPEN_ERROR_PROMISC_PERM_DENIED:
snprintf(errmsg, errmsg_len,
"You do not have permission to capture in promiscuous mode on device \"%s\".\n(%s)",
iface, open_status_str);
break;
case CAP_DEVICE_OPEN_ERROR_OTHER:
default:
snprintf(errmsg, errmsg_len,
"The capture session could not be initiated on capture device \"%s\".\n(%s)",
iface, open_status_str);
break;
}
snprintf(secondary_errmsg, secondary_errmsg_len, "%s",
get_pcap_failure_secondary_error_message(open_status, open_status_str));
}
static gboolean
compile_capture_filter(const char *iface, pcap_t *pcap_h,
struct bpf_program *fcode, const char *cfilter)
{
bpf_u_int32 netnum, netmask;
gchar lookup_net_err_str[PCAP_ERRBUF_SIZE];
if (pcap_lookupnet(iface, &netnum, &netmask, lookup_net_err_str) < 0) {
/*
* Well, we can't get the netmask for this interface; it's used
* only for filters that check for broadcast IP addresses, so
* we just punt and use 0. It might be nice to warn the user,
* but that's a pain in a GUI application, as it'd involve popping
* up a message box, and it's not clear how often this would make
* a difference (only filters that check for IP broadcast addresses
* use the netmask).
*/
/*cmdarg_err(
"Warning: Couldn't obtain netmask info (%s).", lookup_net_err_str);*/
netmask = 0;
}
/*
* Sigh. Older versions of libpcap don't properly declare the
* third argument to pcap_compile() as a const pointer. Cast
* away the warning.
*/
DIAG_OFF(cast-qual)
if (pcap_compile(pcap_h, fcode, (char *)cfilter, 1, netmask) < 0)
return FALSE;
DIAG_ON(cast-qual)
return TRUE;
}
static gboolean
show_filter_code(capture_options *capture_opts)
{
interface_options *interface_opts;
pcap_t *pcap_h;
cap_device_open_status open_status;
gchar open_status_str[PCAP_ERRBUF_SIZE];
char errmsg[MSG_MAX_LENGTH+1];
char secondary_errmsg[MSG_MAX_LENGTH+1];
struct bpf_program fcode;
struct bpf_insn *insn;
u_int i;
guint j;
for (j = 0; j < capture_opts->ifaces->len; j++) {
interface_opts = &g_array_index(capture_opts->ifaces, interface_options, j);
pcap_h = open_capture_device(capture_opts, interface_opts,
CAP_READ_TIMEOUT, &open_status, &open_status_str);
if (pcap_h == NULL) {
/* Open failed; get messages */
get_capture_device_open_failure_messages(open_status, open_status_str,
interface_opts->name,
errmsg, sizeof errmsg,
secondary_errmsg,
sizeof secondary_errmsg);
/* And report them */
report_capture_error(errmsg, secondary_errmsg);
return FALSE;
}
/* Set the link-layer type. */
if (!set_pcap_datalink(pcap_h, interface_opts->linktype, interface_opts->name,
errmsg, sizeof errmsg,
secondary_errmsg, sizeof secondary_errmsg)) {
pcap_close(pcap_h);
report_capture_error(errmsg, secondary_errmsg);
return FALSE;
}
/* OK, try to compile the capture filter. */
if (!compile_capture_filter(interface_opts->name, pcap_h, &fcode,
interface_opts->cfilter)) {
snprintf(errmsg, sizeof(errmsg), "%s", pcap_geterr(pcap_h));
pcap_close(pcap_h);
report_cfilter_error(capture_opts, j, errmsg);
return FALSE;
}
pcap_close(pcap_h);
/* Now print the filter code. */
insn = fcode.bf_insns;
for (i = 0; i < fcode.bf_len; insn++, i++)
printf("%s\n", bpf_image(insn, i));
}
/* If not using libcap: we now can now set euid/egid to ruid/rgid */
/* to remove any suid privileges. */
/* If using libcap: we can now remove NET_RAW and NET_ADMIN capabilities */
/* (euid/egid have already previously been set to ruid/rgid. */
/* (See comment in main() for details) */
#ifndef HAVE_LIBCAP
relinquish_special_privs_perm();
#else
relinquish_all_capabilities();
#endif
if (capture_child) {
/* Let our parent know we succeeded. */
sync_pipe_write_string_msg(2, SP_SUCCESS, NULL);
}
return TRUE;
}
/*
* Output a machine readable list of the interfaces
* This list is retrieved by the sync_interface_list_open() function
* The actual output of this function can be viewed with the command "dumpcap -D -Z none"
*/
static void
print_machine_readable_interfaces(GList *if_list)
{
int i;
GList *if_entry;
if_info_t *if_info;
GSList *addr;
if_addr_t *if_addr;
char addr_str[WS_INET6_ADDRSTRLEN];
if (capture_child) {
/* Let our parent know we succeeded. */
sync_pipe_write_string_msg(2, SP_SUCCESS, NULL);
}
i = 1; /* Interface id number */
for (if_entry = g_list_first(if_list); if_entry != NULL;
if_entry = g_list_next(if_entry)) {
if_info = (if_info_t *)if_entry->data;
printf("%d. %s\t", i++, if_info->name);
/*
* Print the contents of the if_entry struct in a parseable format.
* Each if_entry element is tab-separated. Addresses are comma-
* separated.
*/
/* XXX - Make sure our description doesn't contain a tab */
if (if_info->vendor_description != NULL)
printf("%s\t", if_info->vendor_description);
else
printf("\t");