/* 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"); }