hush: HUSH_READONLY depends on HUSH

[oweals/busybox.git] / libbb / die_if_bad_username.c

diff --git a/libbb/die_if_bad_username.c b/libbb/die_if_bad_username.c
index 602aadc0cf973a40514b9abb366276db587685fd..cf1297bd6a9d344deec392cb97a8775f49fa7ace 100644 (file)
--- a/libbb/die_if_bad_username.c
+++ b/libbb/die_if_bad_username.c
@@ -1,10 +1,10 @@
 /* vi: set sw=4 ts=4: */
 /*
- * Ckeck user and group names for illegal characters
+ * Check user and group names for illegal characters
  *
  * Copyright (C) 2008 Tito Ragusa <farmatito@tiscali.it>
  *
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 
 #include "libbb.h"
@@ -18,19 +18,45 @@
 
 void FAST_FUNC die_if_bad_username(const char *name)
 {
-       goto skip; /* 1st char being dash isn't valid */
+       const char *start = name;
+
+       /* 1st char being dash or dot isn't valid:
+        * for example, name like ".." can make adduser
+        * chown "/home/.." recursively - NOT GOOD.
+        * Name of just a single "$" is also rejected.
+        */
+       goto skip;
+
        do {
-               if (*name == '-')
+               unsigned char ch;
+
+               /* These chars are valid unless they are at the 1st pos: */
+               if (*name == '-'
+                || *name == '.'
+               /* $ is allowed if it's the last char: */
+                || (*name == '$' && !name[1])
+               ) {
                        continue;
+               }
  skip:
-               if (isalnum(*name)
-                || *name == '_'
-                || *name == '.'
-                || *name == '@'
-                || (*name == '$' && !*(name + 1))
+               ch = *name;
+               if (ch == '_'
+               /* || ch == '@' -- we disallow this too. Think about "user@host" */
+               /* open-coded isalnum: */
+                || (ch >= '0' && ch <= '9')
+                || ((ch|0x20) >= 'a' && (ch|0x20) <= 'z')
                ) {
                        continue;
                }
-               bb_error_msg_and_die("illegal character '%c'", *name);
+               bb_error_msg_and_die("illegal character with code %u at position %u",
+                               (unsigned)ch, (unsigned)(name - start));
        } while (*++name);
+
+       /* The minimum size of the login name is one char or two if
+        * last char is the '$'. Violations of this are caught above.
+        * The maximum size of the login name is LOGIN_NAME_MAX
+        * including the terminating null byte.
+        */
+       if (name - start >= LOGIN_NAME_MAX)
+               bb_error_msg_and_die("name is too long");
 }