# HG changeset patch
# User Todd C. Miller <Todd.Miller@sudo.ws>
# Date 1611416639 25200
# Node ID 049ad90590be1e5dfb7df2675d2eb3e37c96ab86
# Parent  a97dc92eae6b60ae285055441341d493c17262ff
Fix potential buffer overflow when unescaping backslashes in user_args.
Also, do not try to unescaping backslashes unless in run mode *and*
we are running the command via a shell.
Found by Qualys, this fixes CVE-2021-3156.

diff -r a97dc92eae6b -r 049ad90590be plugins/sudoers/sudoers.c
--- a/plugins/sudoers/sudoers.c	Sat Jan 23 08:43:59 2021 -0700
+++ b/plugins/sudoers/sudoers.c	Sat Jan 23 08:43:59 2021 -0700
@@ -547,7 +547,7 @@
 
     /* If run as root with SUDO_USER set, set sudo_user.pw to that user. */
     /* XXX - causes confusion when root is not listed in sudoers */
-    if (sudo_mode & (MODE_RUN | MODE_EDIT) && prev_user != NULL) {
+    if (ISSET(sudo_mode, MODE_RUN|MODE_EDIT) && prev_user != NULL) {
 	if (user_uid == 0 && strcmp(prev_user, "root") != 0) {
 	    struct passwd *pw;
 
@@ -932,8 +932,8 @@
     if (user_cmnd == NULL)
 	user_cmnd = NewArgv[0];
 
-    if (sudo_mode & (MODE_RUN | MODE_EDIT | MODE_CHECK)) {
-	if (ISSET(sudo_mode, MODE_RUN | MODE_CHECK)) {
+    if (ISSET(sudo_mode, MODE_RUN|MODE_EDIT|MODE_CHECK)) {
+	if (!ISSET(sudo_mode, MODE_EDIT)) {
 	    if (def_secure_path && !user_is_exempt())
 		path = def_secure_path;
 	    if (!set_perms(PERM_RUNAS))
@@ -961,7 +961,8 @@
 		sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
 		debug_return_int(NOT_FOUND_ERROR);
 	    }
-	    if (ISSET(sudo_mode, MODE_SHELL|MODE_LOGIN_SHELL)) {
+	    if (ISSET(sudo_mode, MODE_SHELL|MODE_LOGIN_SHELL) &&
+		    ISSET(sudo_mode, MODE_RUN)) {
 		/*
 		 * When running a command via a shell, the sudo front-end
 		 * escapes potential meta chars.  We unescape non-spaces
@@ -969,10 +970,22 @@
 		 */
 		for (to = user_args, av = NewArgv + 1; (from = *av); av++) {
 		    while (*from) {
-			if (from[0] == '\\' && !isspace((unsigned char)from[1]))
+			if (from[0] == '\\' && from[1] != '\0' &&
+				!isspace((unsigned char)from[1])) {
 			    from++;
+			}
+			if (size - (to - user_args) < 1) {
+			    sudo_warnx(U_("internal error, %s overflow"),
+				__func__);
+			    debug_return_int(NOT_FOUND_ERROR);
+			}
 			*to++ = *from++;
 		    }
+		    if (size - (to - user_args) < 1) {
+			sudo_warnx(U_("internal error, %s overflow"),
+			    __func__);
+			debug_return_int(NOT_FOUND_ERROR);
+		    }
 		    *to++ = ' ';
 		}
 		*--to = '\0';


# HG changeset patch
# User Todd C. Miller <Todd.Miller@sudo.ws>
# Date 1611416639 25200
# Node ID 9b97f1787804aedccaec63c379053b1a91a0e409
# Parent  90aba6ba6e03f3bc33b4eabf16358396ed83642d
Reset valid_flags to MODE_NONINTERACTIVE for sudoedit.
This is consistent with how the -e option is handled.
Also reject -H and -P flags for sudoedit as was done in sudo 1.7.
Found by Qualys, this is part of the fix for CVE-2021-3156.

diff -r 90aba6ba6e03 -r 9b97f1787804 src/parse_args.c
--- a/src/parse_args.c	Mon Jan 18 12:30:52 2021 +0100
+++ b/src/parse_args.c	Sat Jan 23 08:43:59 2021 -0700
@@ -117,7 +117,10 @@
 /*
  * Default flags allowed when running a command.
  */
-#define DEFAULT_VALID_FLAGS	(MODE_BACKGROUND|MODE_PRESERVE_ENV|MODE_RESET_HOME|MODE_LOGIN_SHELL|MODE_NONINTERACTIVE|MODE_SHELL)
+#define DEFAULT_VALID_FLAGS	(MODE_BACKGROUND|MODE_PRESERVE_ENV|MODE_RESET_HOME|MODE_LOGIN_SHELL|MODE_NONINTERACTIVE|MODE_PRESERVE_GROUPS|MODE_SHELL)
+#define EDIT_VALID_FLAGS	MODE_NONINTERACTIVE
+#define LIST_VALID_FLAGS	(MODE_NONINTERACTIVE|MODE_LONG_LIST)
+#define VALIDATE_VALID_FLAGS	MODE_NONINTERACTIVE
 
 /* Option number for the --host long option due to ambiguity of the -h flag. */
 #define OPT_HOSTNAME	256
@@ -262,6 +265,7 @@
 	progname = "sudoedit";
 	mode = MODE_EDIT;
 	sudo_settings[ARG_SUDOEDIT].value = "true";
+	valid_flags = EDIT_VALID_FLAGS;
     }
 
     /* Load local IP addresses and masks. */
@@ -365,7 +369,7 @@
 			usage_excl();
 		    mode = MODE_EDIT;
 		    sudo_settings[ARG_SUDOEDIT].value = "true";
-		    valid_flags = MODE_NONINTERACTIVE;
+		    valid_flags = EDIT_VALID_FLAGS;
 		    break;
 		case 'g':
 		    assert(optarg != NULL);
@@ -377,6 +381,7 @@
 		    break;
 		case 'H':
 		    sudo_settings[ARG_SET_HOME].value = "true";
+		    SET(flags, MODE_RESET_HOME);
 		    break;
 		case 'h':
 		    if (optarg == NULL) {
@@ -431,7 +436,7 @@
 			    usage_excl();
 		    }
 		    mode = MODE_LIST;
-		    valid_flags = MODE_NONINTERACTIVE|MODE_LONG_LIST;
+		    valid_flags = LIST_VALID_FLAGS;
 		    break;
 		case 'n':
 		    SET(flags, MODE_NONINTERACTIVE);
@@ -439,6 +444,7 @@
 		    break;
 		case 'P':
 		    sudo_settings[ARG_PRESERVE_GROUPS].value = "true";
+		    SET(flags, MODE_PRESERVE_GROUPS);
 		    break;
 		case 'p':
 		    /* An empty prompt is allowed. */
@@ -505,7 +511,7 @@
 		    if (mode && mode != MODE_VALIDATE)
 			usage_excl();
 		    mode = MODE_VALIDATE;
-		    valid_flags = MODE_NONINTERACTIVE;
+		    valid_flags = VALIDATE_VALID_FLAGS;
 		    break;
 		case 'V':
 		    if (mode && mode != MODE_VERSION)
@@ -533,7 +539,7 @@
     if (!mode) {
 	/* Defer -k mode setting until we know whether it is a flag or not */
 	if (sudo_settings[ARG_IGNORE_TICKET].value != NULL) {
-	    if (argc == 0 && !(flags & (MODE_SHELL|MODE_LOGIN_SHELL))) {
+	    if (argc == 0 && !ISSET(flags, MODE_SHELL|MODE_LOGIN_SHELL)) {
 		mode = MODE_INVALIDATE;	/* -k by itself */
 		sudo_settings[ARG_IGNORE_TICKET].value = NULL;
 		valid_flags = 0;
@@ -601,7 +607,7 @@
     /*
      * For shell mode we need to rewrite argv
      */
-    if (ISSET(mode, MODE_RUN) && ISSET(flags, MODE_SHELL)) {
+    if (ISSET(flags, MODE_SHELL|MODE_LOGIN_SHELL) && ISSET(mode, MODE_RUN)) {
 	char **av, *cmnd = NULL;
 	int ac = 1;