X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/d5be981c91f153934cda3361567c857fc8d64886..refs/pull/435/head:/tcpdump.c

diff --git a/tcpdump.c b/tcpdump.c
index 1eb2e206..8e07d8f2 100644
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -101,10 +101,18 @@ extern int SIZE_BUF;
 #include <grp.h>
 #endif /* WIN32 */
 
-/* capabilities convinience library */
+/* capabilities convenience library */
+/* If a code depends on HAVE_LIBCAP_NG, it depends also on HAVE_CAP_NG_H.
+ * If HAVE_CAP_NG_H is not defined, undefine HAVE_LIBCAP_NG.
+ * Thus, the later tests are done only on HAVE_LIBCAP_NG.
+ */
+#ifdef HAVE_LIBCAP_NG
 #ifdef HAVE_CAP_NG_H
 #include <cap-ng.h>
+#else
+#undef HAVE_LIBCAP_NG
 #endif /* HAVE_CAP_NG_H */
+#endif /* HAVE_LIBCAP_NG */
 
 #include "netdissect.h"
 #include "interface.h"
@@ -734,7 +742,7 @@ droproot(const char *username, const char *chroot_dir)
 				exit(1);
 			}
 		}
-#ifdef HAVE_CAP_NG_H
+#ifdef HAVE_LIBCAP_NG
 		int ret = capng_change_id(pw->pw_uid, pw->pw_gid, CAPNG_NO_FLAG);
 		if (ret < 0) {
 			fprintf(stderr, "error : ret %d\n", ret);
@@ -742,15 +750,6 @@ droproot(const char *username, const char *chroot_dir)
 		else {
 			fprintf(stderr, "dropped privs to %s\n", username);
 		}
-		/* We don't need CAP_SETUID and CAP_SETGID */
-		capng_updatev(
-			CAPNG_DROP,
-			CAPNG_EFFECTIVE | CAPNG_PERMITTED,
-			CAP_SETUID,
-			CAP_SETGID,
-			-1);
-		capng_apply(CAPNG_SELECT_BOTH);
-
 #else
 		if (initgroups(pw->pw_name, pw->pw_gid) != 0 ||
 		    setgid(pw->pw_gid) != 0 || setuid(pw->pw_uid) != 0) {
@@ -764,13 +763,24 @@ droproot(const char *username, const char *chroot_dir)
 		else {
 			fprintf(stderr, "dropped privs to %s\n", username);
 		}
-#endif /* HAVE_CAP_NG_H */
+#endif /* HAVE_LIBCAP_NG */
 	}
 	else {
 		fprintf(stderr, "tcpdump: Couldn't find user '%.32s'\n",
 		    username);
 		exit(1);
 	}
+#ifdef HAVE_LIBCAP_NG
+	/* We don't need CAP_SETUID and CAP_SETGID any more. */
+	capng_updatev(
+		CAPNG_DROP,
+		CAPNG_EFFECTIVE | CAPNG_PERMITTED,
+		CAP_SETUID,
+		CAP_SETGID,
+		-1);
+	capng_apply(CAPNG_SELECT_BOTH);
+#endif /* HAVE_LIBCAP_NG */
+
 }
 #endif /* WIN32 */
 
@@ -1582,7 +1592,7 @@ main(int argc, char **argv)
 			status = pcap_set_tstamp_type(pd, jflag);
 			if (status < 0)
 				error("%s: Can't set time stamp type: %s",
-			    	    device, pcap_statustostr(status));
+			              device, pcap_statustostr(status));
 		}
 #endif
 		status = pcap_activate(pd);
@@ -1729,22 +1739,27 @@ main(int argc, char **argv)
 	 */
 
 	if (getuid() == 0 || geteuid() == 0) {
-#ifdef HAVE_CAP_NG_H
-		/* Drop all capabilities from effective set */
-		capng_clear(CAPNG_EFFECTIVE);
-		/* We are running as root and we will be writing to savefile */
-		if (WFileName  && username) {
-			/* Add capabilities we will need*/
+#ifdef HAVE_LIBCAP_NG
+		/* Initialize capng */
+		capng_clear(CAPNG_SELECT_BOTH);
+		if (username) {
 			capng_updatev(
 				CAPNG_ADD,
 				CAPNG_PERMITTED | CAPNG_EFFECTIVE,
 				CAP_SETUID,
 				CAP_SETGID,
-				CAP_DAC_OVERRIDE,
 				-1);
-			capng_apply(CAPNG_SELECT_BOTH);
 		}
-#endif /* HAVE_CAP_NG_H */
+
+		if (WFileName) {
+			capng_update(
+				CAPNG_ADD,
+				CAPNG_PERMITTED | CAPNG_EFFECTIVE,
+				CAP_DAC_OVERRIDE
+				);
+		}
+		capng_apply(CAPNG_SELECT_BOTH);
+#endif /* HAVE_LIBCAP_NG */
 		if (username || chroot_dir)
 			droproot(username, chroot_dir);
 
@@ -1783,10 +1798,19 @@ main(int argc, char **argv)
 		  MakeFilename(dumpinfo.CurrentFileName, WFileName, 0, 0);
 
 		p = pcap_dump_open(pd, dumpinfo.CurrentFileName);
-#ifdef HAVE_CAP_NG_H
-        /* Give up capabilities, clear Effective set */
-        capng_clear(CAPNG_EFFECTIVE);
-#endif
+#ifdef HAVE_LIBCAP_NG
+		/* Give up CAP_DAC_OVERRIDE capability.
+		 * Only allow it to be restored if the -C or -G flag have been
+		 * set since we may need to create more files later on.
+		 */
+		capng_update(
+			CAPNG_DROP,
+			(Cflag || Gflag ? 0 : CAPNG_PERMITTED)
+				| CAPNG_EFFECTIVE,
+			CAP_DAC_OVERRIDE
+			);
+		capng_apply(CAPNG_SELECT_BOTH);
+#endif /* HAVE_LIBCAP_NG */
 		if (p == NULL)
 			error("%s", pcap_geterr(pd));
 #ifdef HAVE_CAPSICUM
@@ -2200,10 +2224,10 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s
 			else
 				MakeFilename(dump_info->CurrentFileName, dump_info->WFileName, 0, 0);
 
-#ifdef HAVE_CAP_NG_H
+#ifdef HAVE_LIBCAP_NG
 			capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
-			capng_apply(CAPNG_EFFECTIVE);
-#endif /* HAVE_CAP_NG_H */
+			capng_apply(CAPNG_SELECT_BOTH);
+#endif /* HAVE_LIBCAP_NG */
 #ifdef HAVE_CAPSICUM
 			fd = openat(dump_info->dirfd,
 			    dump_info->CurrentFileName,
@@ -2221,10 +2245,10 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s
 #else	/* !HAVE_CAPSICUM */
 			dump_info->p = pcap_dump_open(dump_info->pd, dump_info->CurrentFileName);
 #endif
-#ifdef HAVE_CAP_NG_H
+#ifdef HAVE_LIBCAP_NG
 			capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
-			capng_apply(CAPNG_EFFECTIVE);
-#endif /* HAVE_CAP_NG_H */
+			capng_apply(CAPNG_SELECT_BOTH);
+#endif /* HAVE_LIBCAP_NG */
 			if (dump_info->p == NULL)
 				error("%s", pcap_geterr(pd));
 #ifdef HAVE_CAPSICUM
@@ -2242,59 +2266,74 @@ 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);
+#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
-		if (dump_info->p == NULL)
-			error("%s", pcap_geterr(pd));
+#ifdef HAVE_LIBCAP_NG
+			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));
 #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");
-		}
+			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");
+			}
 #endif
+		}
 	}
 
 	pcap_dump((u_char *)dump_info->p, h, sp);