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/* vi: set sw=4 ts=4: */
/*
* 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 source tree.
*/
#include "libbb.h"
/* To avoid problems, the username should consist only of
* letters, digits, underscores, periods, at signs and dashes,
* and not start with a dash (as defined by IEEE Std 1003.1-2001).
* For compatibility with Samba machine accounts $ is also supported
* at the end of the username.
*/
void FAST_FUNC die_if_bad_username(const char *name)
{
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 {
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");
}
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