/* 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"
* at the end of the username.
*/
-void die_if_bad_username(const char *name)
+void FAST_FUNC die_if_bad_username(const char *name)
{
- int i = 0;
+ 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 "$" is also rejected.
+ */
+ goto skip;
do {
- if (!isalnum(*name)
- && !(*name == '_')
- && !(*name == '.')
- && !(*name == '@')
- && !(*name == '-' && i)
- && !(*name == '$' && !*(name + 1))
- )
- bb_error_msg_and_die("illegal character '%c'", *name);
- i++;
+ 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 == '$' && !name[1])
+ ) {
+ continue;
+ }
+ skip:
+ ch = *name;
+ if (ch == '_'
+ /* || ch == '@' -- we disallow this too. Think about "user@host" */
+ /* open-coded isalnum: */
+ || (ch >= '0' && ch <= '9')
+ || ((ch|0x20) >= 'a' && (ch|0x20) <= 'z')
+ ) {
+ continue;
+ }
+ bb_error_msg_and_die("illegal character with code %u at position %u",
+ (unsigned)ch, (unsigned)(name - start));
} while (*++name);
+
+ /* The minimum size of the login name is one char or two if
+ * last char is the '$'. 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");
}