forked from osmocom/wireshark
Extcap: Create our fifo in a temporary directory.
Instead of creating a temp file, unlinking it, and creating a fifo with the same name, add create_tempdir() so that we can create a temporary directory and create a fifo inside that. This should avoid a race condition in Carbon Black Cloud antivirus, which if the timing is right, will stat the initial temporary *file*, miss the fact that it's been replaced with a *fifo*, and open and steal data^W^W read from it, leaving dumpcap to contend with the truncated remains. Adding the unexpected magic number to cap_pipe_open_live()'s error message helped to debug this. Leave it in since it's handy to have in that case. Ping #15587
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5aa1871ee0
commit
cb420c7911
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@ -1850,7 +1850,7 @@ cap_pipe_open_live(char *pipename,
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/* Not a pcapng file, and either not a pcap type we know about
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or not a pcap file, either. */
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snprintf(errmsg, (gulong)errmsgl,
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"Data written to the pipe is neither in a supported pcap format nor in pcapng format.");
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"File type is neither a supported pcap nor pcapng format. (magic = 0x%08x)", magic);
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snprintf(secondary_errmsg, (gulong)secondary_errmsgl, "%s",
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not_our_bug);
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goto error;
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28
extcap.c
28
extcap.c
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@ -1354,6 +1354,8 @@ gboolean extcap_session_stop(capture_session *cap_session)
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}
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/* the fifo will not be freed here, but with the other capture_opts in capture_sync */
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ws_unlink(interface_opts->extcap_fifo);
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get_dirname(interface_opts->extcap_fifo);
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rmdir(interface_opts->extcap_fifo);
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interface_opts->extcap_fifo = NULL;
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}
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if (interface_opts->extcap_control_in && file_exists(interface_opts->extcap_control_in))
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@ -1661,33 +1663,27 @@ static gboolean extcap_create_pipe(const gchar *ifname, gchar **fifo, HANDLE *ha
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#else
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static gboolean extcap_create_pipe(const gchar *ifname, gchar **fifo, const gchar *temp_dir, const gchar *pipe_prefix)
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{
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gchar *temp_name = NULL;
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int fd = 0;
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gchar *subdir_tmpl = g_strdup_printf("%s_%s_XXXXXX", pipe_prefix, ifname);
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gchar *temp_subdir = create_tempdir(temp_dir, subdir_tmpl, NULL);
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gchar *pfx = g_strconcat(pipe_prefix, "_", ifname, NULL);
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if ((fd = create_tempfile(temp_dir, &temp_name, pfx, NULL, NULL)) < 0)
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g_free(subdir_tmpl);
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if (temp_subdir == NULL)
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{
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g_free(pfx);
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return FALSE;
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}
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g_free(pfx);
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ws_close(fd);
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gchar *fifo_path = g_build_path(G_DIR_SEPARATOR_S, temp_subdir, "fifo", NULL);
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g_free(temp_subdir);
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ws_debug("Extcap - Creating fifo: %s", temp_name);
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ws_debug("Extcap - Creating fifo: %s", fifo_path);
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if (file_exists(temp_name))
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if (mkfifo(fifo_path, 0600) == 0)
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{
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ws_unlink(temp_name);
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}
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if (mkfifo(temp_name, 0600) == 0)
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{
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*fifo = temp_name;
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*fifo = fifo_path;
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}
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else
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{
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g_free(temp_name);
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g_free(fifo_path);
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}
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return TRUE;
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}
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@ -15,6 +15,28 @@
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#include "tempfile.h"
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#include "file_util.h"
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static char *
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sanitize_prefix(const char *prefix)
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{
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if (!prefix) {
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return NULL;
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}
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/* The characters in "delimiters" come from:
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* https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#naming-conventions.
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* Add to the list as necessary for other OS's.
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*/
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const gchar *delimiters = "<>:\"/\\|?*"
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"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a"
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"\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14"
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"\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
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/* Sanitize the prefix to resolve bug 7877 */
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char *safe_prefx = g_strdup(prefix);
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safe_prefx = g_strdelimit(safe_prefx, delimiters, '-');
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return safe_prefx;
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}
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/**
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* Create a tempfile with the given prefix (e.g. "wireshark"). The path
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* is created using g_file_open_tmp.
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@ -32,22 +54,7 @@ int
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create_tempfile(const char *tempdir, gchar **namebuf, const char *pfx, const char *sfx, GError **err)
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{
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int fd;
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gchar *safe_pfx = NULL;
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if (pfx) {
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/* The characters in "delimiters" come from:
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* https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#naming-conventions.
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* Add to the list as necessary for other OS's.
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*/
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const gchar *delimiters = "<>:\"/\\|?*"
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"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a"
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"\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14"
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"\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
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/* Sanitize the pfx to resolve bug 7877 */
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safe_pfx = g_strdup(pfx);
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safe_pfx = g_strdelimit(safe_pfx, delimiters, '-');
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}
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gchar *safe_pfx = sanitize_prefix(pfx);
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if (tempdir == NULL || tempdir[0] == '\0') {
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/* Use OS default tempdir behaviour */
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@ -107,6 +114,31 @@ create_tempfile(const char *tempdir, gchar **namebuf, const char *pfx, const cha
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return fd;
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}
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char *
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create_tempdir(const gchar *parent_dir, const char *tmpl, GError **err)
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{
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if (parent_dir == NULL || parent_dir[0] == '\0') {
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parent_dir = g_get_tmp_dir();
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}
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gchar *safe_pfx = sanitize_prefix(tmpl);
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if (safe_pfx == NULL) {
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safe_pfx = g_strdup("wireshark_XXXXXX");
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}
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char *temp_subdir = g_build_path(G_DIR_SEPARATOR_S, parent_dir, safe_pfx, NULL);
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g_free(safe_pfx);
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if (g_mkdtemp(temp_subdir) == NULL)
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{
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g_free(temp_subdir);
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g_set_error_literal(err, G_FILE_ERROR,
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g_file_error_from_errno(errno), g_strerror(errno));
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return FALSE;
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}
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return temp_subdir;
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}
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/*
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* Editor modelines - https://www.wireshark.org/tools/modelines.html
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*
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@ -27,7 +27,7 @@ extern "C" {
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*
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* @param tempdir [in] If not NULL, the directory in which to create the file.
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* @param namebuf [in,out] If not NULL, receives the full path of the temp file.
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* Must be freed.
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* Must be g_freed.
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* @param pfx [in] A prefix for the temporary file.
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* @param sfx [in] A file extension for the temporary file. NULL can be passed
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* if no file extension is needed
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@ -36,6 +36,18 @@ extern "C" {
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*/
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WS_DLL_PUBLIC int create_tempfile(const gchar *tempdir, gchar **namebuf, const char *pfx, const char *sfx, GError **err);
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/**
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* Create a tempfile with the given parent directory (e.g. "/my/private/tmp"). The path
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* is created using g_mkdtemp.
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*
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* @param parent_dir [in] If not NULL, the parent directory in which to create the subdirectory,
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* otherwise the system temporary directory is used.
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* @param tmpl [in] A template for the temporary directory.
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* @param err [out] Any error returned by g_mkdtemp. May be NULL.
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* @return The full path of the temporary directory or NULL on error. Must be g_freed.
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*/
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WS_DLL_PUBLIC char *create_tempdir(const gchar *parent_dir, const char *tmpl, GError **err);
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#ifdef __cplusplus
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}
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#endif /* __cplusplus */
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