system/sudo: patch CVE-2021-3156

1 files changed, 165 insertions, 0 deletions

diff --git a/system/sudo/CVE-2021-3156.patch b/system/sudo/CVE-2021-3156.patch
new file mode 100644
index 000000000..7cb492d61
--- /dev/null
+++ b/system/sudo/CVE-2021-3156.patch
@@ -0,0 +1,165 @@
+
+# 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;
+ 
+