From f57629c95308cb87da059c37722bb8b65217f318 Mon Sep 17 00:00:00 2001
From: "Todd C. Miller" <Todd.Miller@courtesan.com>
Date: Thu, 27 Apr 2017 12:28:08 -0600
Subject: [PATCH] On Linux, if the command we ran dumped core, set
 PR_SET_DUMPABLE to 0.  This will prevent sudo itself from dumping core in
 this case.

---
 src/sudo.c | 60 ++++++++++++++++++++++++++++++++----------------------
 1 file changed, 36 insertions(+), 24 deletions(-)

diff --git a/src/sudo.c b/src/sudo.c
index 0af1433f8..b5a081d02 100644
--- a/src/sudo.c
+++ b/src/sudo.c
@@ -70,6 +70,9 @@
 # endif /* __hpux */
 # include <prot.h>
 #endif /* HAVE_GETPRPWNAM && HAVE_SET_AUTH_PARAMETERS */
+#ifdef __linux__
+# include <sys/prctl.h>
+#endif
 
 #include <sudo_usage.h>
 #include "sudo.h"
@@ -104,7 +107,7 @@ static struct sudo_gc_list sudo_gc_list = SLIST_HEAD_INITIALIZER(sudo_gc_list);
  * Local functions
  */
 static void fix_fds(void);
-static void disable_coredumps(void);
+static void disable_coredump(bool restore);
 static void sudo_check_suid(const char *path);
 static char **get_user_info(struct user_details *);
 static void command_info_to_details(char * const info[],
@@ -136,9 +139,6 @@ static void iolog_close(struct plugin_container *plugin, int exit_status,
 static int iolog_show_version(struct plugin_container *plugin, int verbose);
 static void iolog_unlink(struct plugin_container *plugin);
 
-#ifdef RLIMIT_CORE
-static struct rlimit corelimit;
-#endif
 #ifdef __linux__
 static struct rlimit nproclimit;
 #endif
@@ -201,7 +201,8 @@ main(int argc, char *argv[], char *envp[])
 	exit(EXIT_FAILURE); /* get_user_info printed error message */
 
     /* Disable core dumps if not enabled in sudo.conf. */
-    disable_coredumps();
+    if (sudo_conf_disable_coredump())
+	disable_coredump(false);
 
     /* Parse command line arguments. */
     sudo_mode = parse_args(argc, argv, &nargc, &nargv, &settings, &env_add);
@@ -300,11 +301,6 @@ main(int argc, char *argv[], char *envp[])
 	    /* Become full root (not just setuid) so user cannot kill us. */
 	    if (setuid(ROOT_UID) == -1)
 		sudo_warn("setuid(%d)", ROOT_UID);
-	    /* Restore coredumpsize resource limit before running. */
-#ifdef RLIMIT_CORE
-	    if (sudo_conf_disable_coredump())
-		(void) setrlimit(RLIMIT_CORE, &corelimit);
-#endif /* RLIMIT_CORE */
 	    if (ISSET(command_details.flags, CD_SUDOEDIT)) {
 		status = sudo_edit(&command_details);
 	    } else {
@@ -325,7 +321,7 @@ main(int argc, char *argv[], char *envp[])
 	sigaction_t sa;
 
 	if (WCOREDUMP(status))
-	    disable_coredumps();
+	    disable_coredump(false);
 
 	memset(&sa, 0, sizeof(sa));
 	sigemptyset(&sa.sa_mask);
@@ -899,27 +895,39 @@ sudo_check_suid(const char *sudo)
 
 /*
  * Disable core dumps to avoid dropping a core with user password in it.
- * We will reset this limit before executing the command.
+ * Called with restore set to true before executing the command.
  * Not all operating systems disable core dumps for setuid processes.
  */
 static void
-disable_coredumps(void)
+disable_coredump(bool restore)
 {
-#if defined(RLIMIT_CORE)
     struct rlimit rl;
-    debug_decl(disable_coredumps, SUDO_DEBUG_UTIL)
+    static struct rlimit corelimit;
+#ifdef __linux__
+    static int dumpflag;
+#endif
+    debug_decl(disable_coredump, SUDO_DEBUG_UTIL)
 
-    /*
-     * Turn off core dumps?
-     */
-    if (sudo_conf_disable_coredump()) {
-	(void) getrlimit(RLIMIT_CORE, &corelimit);
-	memcpy(&rl, &corelimit, sizeof(struct rlimit));
-	rl.rlim_cur = 0;
-	(void) setrlimit(RLIMIT_CORE, &rl);
+    if (restore) {
+	(void) setrlimit(RLIMIT_CORE, &corelimit);
+#ifdef __linux__
+	(void) prctl(PR_SET_DUMPABLE, dumpflag, 0, 0, 0);
+#endif /* __linux__ */
+	debug_return;
     }
+
+    (void) getrlimit(RLIMIT_CORE, &corelimit);
+    rl.rlim_cur = 0;
+    rl.rlim_max = 0;
+    (void) setrlimit(RLIMIT_CORE, &rl);
+#ifdef __linux__
+    /* On Linux, also set PR_SET_DUMPABLE to zero (reset by execve). */
+    if ((dumpflag = prctl(PR_GET_DUMPABLE, 0, 0, 0, 0)) == -1)
+	dumpflag = 0;
+    (void) prctl(PR_SET_DUMPABLE, 0, 0, 0, 0);
+#endif /* __linux__ */
+
     debug_return;
-#endif /* RLIMIT_CORE */
 }
 
 /*
@@ -1014,6 +1022,10 @@ exec_setup(struct command_details *details, const char *ptyname, int ptyfd)
     }
 #endif
 
+    /* Restore coredumpsize resource limit before running. */
+    if (sudo_conf_disable_coredump())
+	disable_coredump(true);
+
     if (details->pw != NULL) {
 #ifdef HAVE_PROJECT_H
 	set_project(details->pw);
-- 
2.40.0