Alejandro Colomar
ad307ee42a
If (maxsize == -1), then ((size_t)maxsize == SIZE_MAX). And no size can ever be >= SIZE_MAX, so it will never return false if sysconf(3) reports an unlimited user-name size via returning -1. Well, to be pedantic, that disallows a user-name siz of precisely SIZE_MAX bytes when sysconf(3) returns -1. However, that's probably a good thing; such a long user name might trigger Undefined Behavior somewhere else, so be cautious and disallow it. I hope nobody will be using the entire address space for a user name. The commit that introduced that check missed that this code had always supported unlimited user-name sizes since it was introduced by Iker in3b7cc05387("lib: replace `USER_NAME_MAX_LENGTH` macro"), and6be85b0baf("lib/chkname.c: Use tmp variable to avoid a -Wsign-compare warning") even clarified this in the commit message. So, while the code in6a1f45d932("lib/chkname.c: Support unlimited user name lengths") wasn't bad per se, the commit message was incorrect. What that patch did was adding code for handling EINVAL (or any other errors that a future kernel might add). To be more pedantically correct, that commit also allowed (under certain circumstances, user names of SIZE_MAX bytes, but those were originally allowed (by accident), and only became disallowed in403a2e3771("lib/chkname.c: Take NUL byte into account"). But again, let's disallow those, just to be cautious. Link: <https://github.com/shadow-maint/shadow/pull/935> Link: <https://github.com/shadow-maint/shadow/pull/935#discussion_r1477429492> See-also:6be85b0baf("lib/chkname.c: Use tmp variable to avoid a -Wsign-compare warning") Fixes:6a1f45d932("lib/chkname.c: Support unlimited user name lengths") Reviewed-by: Iker Pedrosa <ipedrosa@redhat.com> Cc: Tobias Stoeckmann <tobias@stoeckmann.org> Cc: Serge Hallyn <serge@hallyn.com> Signed-off-by: Alejandro Colomar <alx@kernel.org>
106 lines
2.3 KiB
C
106 lines
2.3 KiB
C
// SPDX-FileCopyrightText: 1990-1994, Julianne Frances Haugh
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// SPDX-FileCopyrightText: 1996-2000, Marek Michałkiewicz
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// SPDX-FileCopyrightText: 2001-2005, Tomasz Kłoczko
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// SPDX-FileCopyrightText: 2005-2008, Nicolas François
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// SPDX-FileCopyrightText: 2023-2024, Alejandro Colomar <alx@kernel.org>
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// SPDX-License-Identifier: BSD-3-Clause
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/*
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* is_valid_user_name(), is_valid_group_name() - check the new user/group
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* name for validity;
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* return values:
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* true - OK
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* false - bad name
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*/
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#include <config.h>
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#ident "$Id$"
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#include <ctype.h>
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#include <errno.h>
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#include <limits.h>
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#include "defines.h"
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#include "chkname.h"
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int allow_bad_names = false;
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static bool is_valid_name (const char *name)
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{
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if (allow_bad_names) {
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return true;
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}
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/*
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* User/group names must match BRE regex:
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* [a-zA-Z0-9_.][a-zA-Z0-9_.-]*$\?
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*
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* as a non-POSIX, extension, allow "$" as the last char for
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* sake of Samba 3.x "add machine script"
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*
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* Also do not allow fully numeric names or just "." or "..".
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*/
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int numeric;
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if ('\0' == *name ||
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('.' == *name && (('.' == name[1] && '\0' == name[2]) ||
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'\0' == name[1])) ||
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!((*name >= 'a' && *name <= 'z') ||
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(*name >= 'A' && *name <= 'Z') ||
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(*name >= '0' && *name <= '9') ||
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*name == '_' ||
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*name == '.')) {
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return false;
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}
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numeric = isdigit(*name);
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while ('\0' != *++name) {
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if (!((*name >= 'a' && *name <= 'z') ||
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(*name >= 'A' && *name <= 'Z') ||
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(*name >= '0' && *name <= '9') ||
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*name == '_' ||
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*name == '.' ||
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*name == '-' ||
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(*name == '$' && name[1] == '\0')
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)) {
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return false;
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}
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numeric &= isdigit(*name);
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}
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return !numeric;
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}
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bool
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is_valid_user_name(const char *name)
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{
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long maxsize;
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errno = 0;
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maxsize = sysconf(_SC_LOGIN_NAME_MAX);
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if (maxsize == -1 && errno != 0)
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maxsize = LOGIN_NAME_MAX;
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if (strlen(name) >= (size_t)maxsize)
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return false;
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return is_valid_name (name);
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}
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bool is_valid_group_name (const char *name)
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{
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/*
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* Arbitrary limit for group names.
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* HP-UX 10 limits to 16 characters
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*/
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if ( (GROUP_NAME_MAX_LENGTH > 0)
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&& (strlen (name) > GROUP_NAME_MAX_LENGTH)) {
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return false;
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}
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return is_valid_name (name);
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}
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