+#ifndef WIN32
+ /*
+ * If a user name was specified with "-Z", attempt to switch to
+ * that user's UID. This would probably be used with sudo,
+ * to allow tcpdump to be run in a special restricted
+ * account (if you just want to allow users to open capture
+ * devices, and can't just give users that permission,
+ * you'd make tcpdump set-UID or set-GID).
+ *
+ * Tcpdump doesn't necessarily write only to one savefile;
+ * the general only way to allow a -Z instance to write to
+ * savefiles as the user under whose UID it's run, rather
+ * than as the user specified with -Z, would thus be to switch
+ * to the original user ID before opening a capture file and
+ * then switch back to the -Z user ID after opening the savefile.
+ * Switching to the -Z user ID only after opening the first
+ * savefile doesn't handle the general case.
+ */
+
+#ifdef HAVE_CAP_NG_H
+ /* We are running as root and we will be writing to savefile */
+ if ((getuid() == 0 || geteuid() == 0) && WFileName) {
+ if (username) {
+ /* Drop all capabilities from effective set */
+ capng_clear(CAPNG_EFFECTIVE);
+ /* Add capabilities we will need*/
+ capng_update(CAPNG_ADD, CAPNG_PERMITTED, CAP_SETUID);
+ capng_update(CAPNG_ADD, CAPNG_PERMITTED, CAP_SETGID);
+ capng_update(CAPNG_ADD, CAPNG_PERMITTED, CAP_DAC_OVERRIDE);
+
+ capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_SETUID);
+ capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_SETGID);
+ capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
+
+ capng_apply(CAPNG_SELECT_BOTH);
+ }
+ }
+#endif /* HAVE_CAP_NG_H */
+
+ if (getuid() == 0 || geteuid() == 0) {
+ if (username || chroot_dir)
+ droproot(username, chroot_dir);
+
+ }
+#endif /* WIN32 */
+
projects / tcpdump / blobdiff