Perform command escaping for "sudo -s" and "sudo -i" after validating

sudoers so the sudoers entries don't need to have all the backslashes.

src/sudo.c

@@ -51,12 +51,13 @@
 #ifdef HAVE_UNISTD_H
 # include <unistd.h>
 #endif /* HAVE_UNISTD_H */
-#include <pwd.h>
+#include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <signal.h>
 #include <grp.h>
+#include <pwd.h>
 #if TIME_WITH_SYS_TIME
 # include <time.h>
 #endif
@@ -117,6 +118,7 @@ static int iolog_open(struct plugin_container *plugin, char * const settings[],
     int argc, char * const argv[], char * const user_env[]);
 static void iolog_close(struct plugin_container *plugin, int exit_status,
     int error);
+static char *escape_cmnd(const char *src);
 
 /* Policy plugin convenience functions. */
 static int policy_open(struct plugin_container *plugin, char * const settings[],
@@ -278,6 +280,12 @@ main(int argc, char *argv[], char *envp[])
 	    if (ISSET(command_details.flags, CD_SUDOEDIT)) {
 		exitcode = sudo_edit(&command_details, argv_out, user_env_out);
 	    } else {
+		if (ISSET(sudo_mode, MODE_SHELL)) {
+		    /* Escape meta chars if running a shell with args. */
+		    if (argv_out[1] != NULL && strcmp(argv_out[1], "-c") == 0 &&
+			argv_out[2] != NULL && argv_out[3] == NULL)
+			argv_out[2] = escape_cmnd(argv_out[2]);
+		}
 		exitcode = run_command(&command_details, argv_out, user_env_out);
 	    }
 	    /* The close method was called by sudo_edit/run_command. */
@@ -907,6 +915,30 @@ done:
     return rval;
 }
 
+/*
+ * Escape any non-alpha numeric or blank characters to make sure
+ * they are not interpreted specially by the shell.
+ */
+static char *
+escape_cmnd(const char *src)
+{
+    char *cmnd, *dst;
+
+    /* Worst case scenario, we have to escape everything. */
+    cmnd = dst = emalloc((2 * strlen(src)) + 1);
+    while (*src != '\0') {
+	if (!isalnum((unsigned char)*src) && !isspace((unsigned char)*src) &&
+	    *src != '_' && *src != '-') {
+	    /* quote potential meta character */
+	    *dst++ = '\\';
+	}
+	*dst++ = *src++;
+    }
+    *dst++ = '\0';
+
+    return cmnd;
+}
+
 /*
  * Run the command and wait for it to complete.
  */