X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/3b7c60978911277414b588871c965d169164bcc2..eec7c9e757ef6d74cc062caf5072505280ef8c3f:/tcpdump.c?ds=inline

diff --git a/tcpdump.c b/tcpdump.c
index 2276961b..07fc6296 100644
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -193,22 +193,12 @@ static void info(int);
 static u_int packets_captured;
 
 struct printer {
-        if_printer f;
-	int type;
-};
-
-
-struct ndo_printer {
-        if_ndo_printer f;
+	if_printer f;
 	int type;
 };
 
 
 static const struct printer printers[] = {
-	{ NULL,			0 },
-};
-
-static const struct ndo_printer ndo_printers[] = {
 	{ ether_if_print,	DLT_EN10MB },
 #ifdef DLT_IPNET
 	{ ipnet_if_print,	DLT_IPNET },
@@ -408,19 +398,6 @@ lookup_printer(int type)
 		if (type == p->type)
 			return p->f;
 
-	return NULL;
-	/* NOTREACHED */
-}
-
-if_ndo_printer
-lookup_ndo_printer(int type)
-{
-	const struct ndo_printer *p;
-
-	for (p = ndo_printers; p->f; ++p)
-		if (type == p->type)
-			return p->f;
-
 #if defined(DLT_USER2) && defined(DLT_PKTAP)
 	/*
 	 * Apple incorrectly chose to use DLT_USER2 for their PKTAP
@@ -439,7 +416,7 @@ lookup_ndo_printer(int type)
 	 * that.
 	 */
 	if (type == DLT_USER2) {
-		for (p = ndo_printers; p->f; ++p)
+		for (p = printers; p->f; ++p)
 			if (DLT_PKTAP == p->type)
 				return p->f;
 	}
@@ -459,11 +436,7 @@ extern char *optarg;
 
 struct print_info {
         netdissect_options *ndo;
-        union {
-                if_printer     printer;
-                if_ndo_printer ndo_printer;
-        } p;
-        int ndo_type;
+        if_printer printer;
 };
 
 struct dump_info {
@@ -548,8 +521,7 @@ show_dlts_and_exit(const char *device, pcap_t *pd)
 			/*
 			 * OK, does tcpdump handle that type?
 			 */
-			if (lookup_printer(dlts[n_dlts]) == NULL
-                            && lookup_ndo_printer(dlts[n_dlts]) == NULL)
+			if (lookup_printer(dlts[n_dlts]) == NULL)
 				(void) fprintf(stderr, " (printing not supported)");
 			fprintf(stderr, "\n");
 		} else {
@@ -607,6 +579,15 @@ show_devices_and_exit (void)
  *
  * OS X tcpdump uses -P to indicate that -w should write pcap-ng rather
  * than pcap files.
+ *
+ * OS X tcpdump also uses -Q to specify expressions that match packet
+ * metadata, including but not limited to the packet direction.
+ * The expression syntax is different from a simple "in|out|inout",
+ * and those expressions aren't accepted by OS X tcpdump, but the
+ * equivalents would be "in" = "dir=in", "out" = "dir=out", and
+ * "inout" = "dir=in or dir=out", and the parser could conceivably
+ * special-case "in", "out", and "inout" as expressions for backwards
+ * compatibility, so all is not (yet) lost.
  */
 
 /*
@@ -655,6 +636,8 @@ show_devices_and_exit (void)
 #define Q_FLAG
 #endif
 
+#define SHORTOPTS "aAb" B_FLAG "c:C:d" D_FLAG "eE:fF:G:hHi:" I_FLAG j_FLAG J_FLAG "KlLm:M:nNOpq" Q_FLAG "r:Rs:StT:u" U_FLAG "vV:w:W:xXy:Yz:Z:#"
+
 /*
  * Long options.
  *
@@ -851,20 +834,15 @@ get_print_info(int type)
 {
 	struct print_info printinfo;
 
-	printinfo.ndo_type = 1;
 	printinfo.ndo = gndo;
-	printinfo.p.ndo_printer = lookup_ndo_printer(type);
-	if (printinfo.p.ndo_printer == NULL) {
-		printinfo.p.printer = lookup_printer(type);
-		printinfo.ndo_type = 0;
-		if (printinfo.p.printer == NULL) {
-			gndo->ndo_dltname = pcap_datalink_val_to_name(type);
-			if (gndo->ndo_dltname != NULL)
-				error("packet printing is not supported for link type %s: use -w",
-				      gndo->ndo_dltname);
-			else
-				error("packet printing is not supported for link type %d: use -w", type);
-		}
+	printinfo.printer = lookup_printer(type);
+	if (printinfo.printer == NULL) {
+		gndo->ndo_dltname = pcap_datalink_val_to_name(type);
+		if (gndo->ndo_dltname != NULL)
+			error("packet printing is not supported for link type %s: use -w",
+			      gndo->ndo_dltname);
+		else
+			error("packet printing is not supported for link type %d: use -w", type);
 	}
 	return (printinfo);
 }
@@ -914,6 +892,76 @@ tstamp_precision_to_string(int precision)
 }
 #endif
 
+#ifdef HAVE_CAPSICUM
+/*
+ * Ensure that, on a dump file's descriptor, we have all the rights
+ * necessary to make the standard I/O library work with an fdopen()ed
+ * FILE * from that descriptor.
+ *
+ * A long time ago, in a galaxy far far away, AT&T decided that, instead
+ * of providing separate APIs for getting and setting the FD_ flags on a
+ * descriptor, getting and setting the O_ flags on a descriptor, and
+ * locking files, they'd throw them all into a kitchen-sink fcntl() call
+ * along the lines of ioctl(), the fact that ioctl() operations are
+ * largely specific to particular character devices but fcntl() operations
+ * are either generic to all descriptors or generic to all descriptors for
+ * regular files nonwithstanding.
+ *
+ * The Capsicum people decided that fine-grained control of descriptor
+ * operations was required, so that you need to grant permission for
+ * reading, writing, seeking, and fcntl-ing.  The latter, courtesy of
+ * AT&T's decision, means that "fcntl-ing" isn't a thing, but a motley
+ * collection of things, so there are *individual* fcntls for which
+ * permission needs to be granted.
+ *
+ * The FreeBSD standard I/O people implemented some optimizations that
+ * requires that the standard I/O routines be able to determine whether
+ * the descriptor for the FILE * is open append-only or not; as that
+ * descriptor could have come from an open() rather than an fopen(),
+ * that requires that it be able to do an F_GETFL fcntl() to read
+ * the O_ flags.
+ *
+ * Tcpdump uses ftell() to determine how much data has been written
+ * to a file in order to, when used with -C, determine when it's time
+ * to rotate capture files.  ftell() therefore needs to do an lseek()
+ * to find out the file offset and must, thanks to the aforementioned
+ * optimization, also know whether the descriptor is open append-only
+ * or not.
+ *
+ * The net result of all the above is that we need to grant CAP_SEEK,
+ * CAP_WRITE, and CAP_FCNTL with the CAP_FCNTL_GETFL subcapability.
+ *
+ * Perhaps this is the universe's way of saying that either
+ *
+ *	1) there needs to be an fopenat() call and a pcap_dump_openat() call
+ *	   using it, so that Capsicum-capable tcpdump wouldn't need to do
+ *	   an fdopen()
+ *
+ * or
+ *
+ *	2) there needs to be a cap_fdopen() call in the FreeBSD standard
+ *	   I/O library that knows what rights are needed by the standard
+ *	   I/O library, based on the open mode, and assigns them, perhaps
+ *	   with an additional argument indicating, for example, whether
+ *	   seeking should be allowed, so that tcpdump doesn't need to know
+ *	   what the standard I/O library happens to require this week.
+ */
+static void
+set_dumper_capsicum_rights(pcap_dumper_t *p)
+{
+	int fd = fileno(pcap_dump_file(p));
+	cap_rights_t rights;
+
+	cap_rights_init(&rights, CAP_SEEK, CAP_WRITE, CAP_FCNTL);
+	if (cap_rights_limit(fd, &rights) < 0 && errno != ENOSYS) {
+		error("unable to limit dump descriptor");
+	}
+	if (cap_fcntls_limit(fd, CAP_FCNTL_GETFL) < 0 && errno != ENOSYS) {
+		error("unable to limit dump descriptor fcntls");
+	}
+}
+#endif
+
 int
 main(int argc, char **argv)
 {
@@ -992,7 +1040,7 @@ main(int argc, char **argv)
 #endif
 
 	while (
-	    (op = getopt_long(argc, argv, "aAb" B_FLAG "c:C:d" D_FLAG "eE:fF:G:hHi:" I_FLAG j_FLAG J_FLAG "KlLm:M:nNOpq" Q_FLAG "r:Rs:StT:u" U_FLAG "vV:w:W:xXy:Yz:Z:#", longopts, NULL)) != -1)
+	    (op = getopt_long(argc, argv, SHORTOPTS, longopts, NULL)) != -1)
 		switch (op) {
 
 		case 'a':
@@ -1814,11 +1862,7 @@ main(int argc, char **argv)
 		if (p == NULL)
 			error("%s", pcap_geterr(pd));
 #ifdef HAVE_CAPSICUM
-		cap_rights_init(&rights, CAP_SEEK, CAP_WRITE);
-		if (cap_rights_limit(fileno(pcap_dump_file(p)), &rights) < 0 &&
-		    errno != ENOSYS) {
-			error("unable to limit dump descriptor");
-		}
+		set_dumper_capsicum_rights(p);
 #endif
 		if (Cflag != 0 || Gflag != 0) {
 #ifdef HAVE_CAPSICUM
@@ -1835,6 +1879,10 @@ main(int argc, char **argv)
 			    errno != ENOSYS) {
 				error("unable to limit directory rights");
 			}
+			if (cap_fcntls_limit(dumpinfo.dirfd, CAP_FCNTL_GETFL) < 0 &&
+			    errno != ENOSYS) {
+				error("unable to limit dump descriptor fcntls");
+			}
 #else	/* !HAVE_CAPSICUM */
 			dumpinfo.WFileName = WFileName;
 #endif
@@ -2139,9 +2187,6 @@ static void
 dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
 {
 	struct dump_info *dump_info;
-#ifdef HAVE_CAPSICUM
-	cap_rights_t rights;
-#endif
 
 	++packets_captured;
 
@@ -2252,11 +2297,7 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s
 			if (dump_info->p == NULL)
 				error("%s", pcap_geterr(pd));
 #ifdef HAVE_CAPSICUM
-			cap_rights_init(&rights, CAP_SEEK, CAP_WRITE);
-			if (cap_rights_limit(fileno(pcap_dump_file(dump_info->p)),
-			    &rights) < 0 && errno != ENOSYS) {
-				error("unable to limit dump descriptor");
-			}
+			set_dumper_capsicum_rights(dump_info->p);
 #endif
 		}
 	}
@@ -2266,67 +2307,70 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s
 	 * larger than Cflag - the last packet written to the
 	 * file could put it over Cflag.
 	 */
-	if (Cflag != 0 && pcap_dump_ftell(dump_info->p) > Cflag) {
+	if (Cflag != 0) {
+		long size = pcap_dump_ftell(dump_info->p);
+
+		if (size == -1)
+			error("ftell fails on output file");
+		if (size > Cflag) {
 #ifdef HAVE_CAPSICUM
-		FILE *fp;
-		int fd;
+			FILE *fp;
+			int fd;
 #endif
 
-		/*
-		 * Close the current file and open a new one.
-		 */
-		pcap_dump_close(dump_info->p);
+			/*
+			 * Close the current file and open a new one.
+			 */
+			pcap_dump_close(dump_info->p);
 
-		/*
-		 * Compress the file we just closed, if the user asked for it
-		 */
-		if (zflag != NULL)
-			compress_savefile(dump_info->CurrentFileName);
+			/*
+			 * Compress the file we just closed, if the user
+			 * asked for it.
+			 */
+			if (zflag != NULL)
+				compress_savefile(dump_info->CurrentFileName);
 
-		Cflag_count++;
-		if (Wflag > 0) {
-			if (Cflag_count >= Wflag)
-				Cflag_count = 0;
-		}
-		if (dump_info->CurrentFileName != NULL)
-			free(dump_info->CurrentFileName);
-		dump_info->CurrentFileName = (char *)malloc(PATH_MAX + 1);
-		if (dump_info->CurrentFileName == NULL)
-			error("dump_packet_and_trunc: malloc");
-		MakeFilename(dump_info->CurrentFileName, dump_info->WFileName, Cflag_count, WflagChars);
+			Cflag_count++;
+			if (Wflag > 0) {
+				if (Cflag_count >= Wflag)
+					Cflag_count = 0;
+			}
+			if (dump_info->CurrentFileName != NULL)
+				free(dump_info->CurrentFileName);
+			dump_info->CurrentFileName = (char *)malloc(PATH_MAX + 1);
+			if (dump_info->CurrentFileName == NULL)
+				error("dump_packet_and_trunc: malloc");
+			MakeFilename(dump_info->CurrentFileName, dump_info->WFileName, Cflag_count, WflagChars);
 #ifdef HAVE_LIBCAP_NG
-		capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
-		capng_apply(CAPNG_SELECT_BOTH);
+			capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
+			capng_apply(CAPNG_SELECT_BOTH);
 #endif /* HAVE_LIBCAP_NG */
 #ifdef HAVE_CAPSICUM
-		fd = openat(dump_info->dirfd, dump_info->CurrentFileName,
-		    O_CREAT | O_WRONLY | O_TRUNC, 0644);
-		if (fd < 0) {
-			error("unable to open file %s",
-			    dump_info->CurrentFileName);
-		}
-		fp = fdopen(fd, "w");
-		if (fp == NULL) {
-			error("unable to fdopen file %s",
-			    dump_info->CurrentFileName);
-		}
-		dump_info->p = pcap_dump_fopen(dump_info->pd, fp);
+			fd = openat(dump_info->dirfd, dump_info->CurrentFileName,
+			    O_CREAT | O_WRONLY | O_TRUNC, 0644);
+			if (fd < 0) {
+				error("unable to open file %s",
+				    dump_info->CurrentFileName);
+			}
+			fp = fdopen(fd, "w");
+			if (fp == NULL) {
+				error("unable to fdopen file %s",
+				    dump_info->CurrentFileName);
+			}
+			dump_info->p = pcap_dump_fopen(dump_info->pd, fp);
 #else	/* !HAVE_CAPSICUM */
-		dump_info->p = pcap_dump_open(dump_info->pd, dump_info->CurrentFileName);
+			dump_info->p = pcap_dump_open(dump_info->pd, dump_info->CurrentFileName);
 #endif
 #ifdef HAVE_LIBCAP_NG
-		capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
-		capng_apply(CAPNG_SELECT_BOTH);
+			capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
+			capng_apply(CAPNG_SELECT_BOTH);
 #endif /* HAVE_LIBCAP_NG */
-		if (dump_info->p == NULL)
-			error("%s", pcap_geterr(pd));
+			if (dump_info->p == NULL)
+				error("%s", pcap_geterr(pd));
 #ifdef HAVE_CAPSICUM
-		cap_rights_init(&rights, CAP_SEEK, CAP_WRITE);
-		if (cap_rights_limit(fileno(pcap_dump_file(dump_info->p)),
-		    &rights) < 0 && errno != ENOSYS) {
-			error("unable to limit dump descriptor");
-		}
+			set_dumper_capsicum_rights(dump_info->p);
 #endif
+		}
 	}
 
 	pcap_dump((u_char *)dump_info->p, h, sp);
@@ -2385,11 +2429,7 @@ print_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
 	 */
 	ndo->ndo_snapend = sp + h->caplen;
 
-        if(print_info->ndo_type) {
-                hdrlen = (*print_info->p.ndo_printer)(print_info->ndo, h, sp);
-        } else {
-                hdrlen = (*print_info->p.printer)(h, sp);
-        }
+        hdrlen = (*print_info->printer)(print_info->ndo, h, sp);
 
 	/*
 	 * Restore the original snapend, as a printer might have