add CAP_EVENT for the libpcap device

[tcpdump] / tcpdump.c

diff --git a/tcpdump.c b/tcpdump.c
index 06c0ca13bca3914bb89507b1d2ed8e742bc52011..e26fbafdd7013dde2b494cbd815d644eb6ccd570 100644 (file)
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -643,12 +643,13 @@ droproot(const char *username, const char *chroot_dir)
                exit_tcpdump(1);
        }
 #ifdef HAVE_LIBCAP_NG
-       /* We don't need CAP_SETUID and CAP_SETGID any more. */
+       /* We don't need CAP_SETUID, CAP_SETGID and CAP_SYS_CHROOT any more. */
        capng_updatev(
                CAPNG_DROP,
                CAPNG_EFFECTIVE | CAPNG_PERMITTED,
                CAP_SETUID,
                CAP_SETGID,
+               CAP_SYS_CHROOT,
                -1);
        capng_apply(CAPNG_SELECT_BOTH);
 #endif /* HAVE_LIBCAP_NG */
@@ -1825,6 +1826,13 @@ main(int argc, char **argv)
                                CAP_SETGID,
                                -1);
                }
+               if (chroot_dir) {
+                       capng_update(
+                               CAPNG_ADD,
+                               CAPNG_PERMITTED | CAPNG_EFFECTIVE,
+                               CAP_SYS_CHROOT
+                               );
+               }
 
                if (WFileName) {
                        capng_update(
@@ -1847,7 +1855,12 @@ main(int argc, char **argv)
        if (RFileName == NULL && VFileName == NULL) {
                static const unsigned long cmds[] = { BIOCGSTATS, BIOCROTZBUF };
 
-               cap_rights_init(&rights, CAP_IOCTL, CAP_READ);
+               /*
+                * The various libpcap devices use a combination of
+                * read (bpf), ioctl (bpf, netmap), poll (netmap)
+                * so we add the relevant access rights.
+                */
+               cap_rights_init(&rights, CAP_IOCTL, CAP_READ, CAP_EVENT);
                if (cap_rights_limit(pcap_fileno(pd), &rights) < 0 &&
                    errno != ENOSYS) {
                        error("unable to limit pcap descriptor");
@@ -2322,6 +2335,7 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s
                        if (Cflag == 0 && Wflag > 0 && Gflag_count >= Wflag) {
                                (void)fprintf(stderr, "Maximum file limit reached: %d\n",
                                    Wflag);
+                               info(1);
                                exit_tcpdump(0);
                                /* NOTREACHED */
                        }