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freebsd-dev/lib/libc/gen/pw_scan.c
Ian Lepore 34e9190d82 Make pw_scan(3) more compatible with getpwent(3) et. al. when processing 
data from /etc/passwd rather than /etc/master.passwd.

The libc getpwent(3) and related functions automatically read master.passwd
when run by root, or passwd when run by a non-root user.  When run by non-
root, getpwent() copes with the missing data by setting the corresponding
fields in the passwd struct to known values (zeroes for numbers, or a
pointer to an empty string for literals).  When libutil's pw_scan(3) was
used to parse a line without the root-accessible data, it was leaving
garbage in the corresponding fields.

These changes rename the static pw_init() function used by getpwent() and
friends to __pw_initpwd(), and move it into pw_scan.c so that common init
code can be shared between libc and libutil.  pw_scan(3) now calls
__pw_initpwd() before __pw_scan(), just like the getpwent() family does, so
that reading an arbitrary passwd file in either format and parsing it with
pw_scan(3) returns the same results as getpwent(3) would.

This also adds a new pw_initpwd(3) function to libutil, so that code which
creates passwd structs from scratch in some manner that doesn't involve
pw_scan() can initialize the struct to the values expected by lots of
existing code, which doesn't expect to encounter NULL pointers or garbage
values in some fields.
2018-07-26 18:34:38 +00:00

227 lines
6.3 KiB
C
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/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1990, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__SCCSID("@(#)pw_scan.c 8.3 (Berkeley) 4/2/94");
__FBSDID("$FreeBSD$");
/*
* This module is used to "verify" password entries by chpass(1) and
* pwd_mkdb(8).
*/
#include <sys/param.h>
#include <err.h>
#include <errno.h>
#include <pwd.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include "pw_scan.h"
/*
* Some software assumes that IDs are short. We should emit warnings
* for id's which cannot be stored in a short, but we are more liberal
* by default, warning for IDs greater than USHRT_MAX.
*
* If pw_big_ids_warning is -1 on entry to pw_scan(), it will be set based
* on the existence of PW_SCAN_BIG_IDS in the environment.
*
* It is believed all baseline system software that can not handle the
* normal ID sizes is now gone so pw_big_ids_warning is disabled for now.
* But the code has been left in place in case end-users want to re-enable
* it and/or for the next time the ID sizes get bigger but pieces of the
* system lag behind.
*/
static int pw_big_ids_warning = 0;
void
__pw_initpwd(struct passwd *pwd)
{
static char nul[] = "";
memset(pwd, 0, sizeof(*pwd));
pwd->pw_uid = (uid_t)-1; /* Considered least likely to lead to */
pwd->pw_gid = (gid_t)-1; /* a security issue. */
pwd->pw_name = nul;
pwd->pw_passwd = nul;
pwd->pw_class = nul;
pwd->pw_gecos = nul;
pwd->pw_dir = nul;
pwd->pw_shell = nul;
}
int
__pw_scan(char *bp, struct passwd *pw, int flags)
{
uid_t id;
int root;
char *ep, *p, *sh;
unsigned long temp;
if (pw_big_ids_warning == -1)
pw_big_ids_warning = getenv("PW_SCAN_BIG_IDS") == NULL ? 1 : 0;
pw->pw_fields = 0;
if (!(pw->pw_name = strsep(&bp, ":"))) /* login */
goto fmt;
root = !strcmp(pw->pw_name, "root");
if (pw->pw_name[0] && (pw->pw_name[0] != '+' || pw->pw_name[1] == '\0'))
pw->pw_fields |= _PWF_NAME;
if (!(pw->pw_passwd = strsep(&bp, ":"))) /* passwd */
goto fmt;
if (pw->pw_passwd[0])
pw->pw_fields |= _PWF_PASSWD;
if (!(p = strsep(&bp, ":"))) /* uid */
goto fmt;
if (p[0])
pw->pw_fields |= _PWF_UID;
else {
if (pw->pw_name[0] != '+' && pw->pw_name[0] != '-') {
if (flags & _PWSCAN_WARN)
warnx("no uid for user %s", pw->pw_name);
return (0);
}
}
errno = 0;
temp = strtoul(p, &ep, 10);
if ((temp == ULONG_MAX && errno == ERANGE) || temp > UID_MAX) {
if (flags & _PWSCAN_WARN)
warnx("%s > max uid value (%u)", p, UID_MAX);
return (0);
}
id = temp;
if (*ep != '\0') {
if (flags & _PWSCAN_WARN)
warnx("%s uid is incorrect", p);
return (0);
}
if (root && id) {
if (flags & _PWSCAN_WARN)
warnx("root uid should be 0");
return (0);
}
if (flags & _PWSCAN_WARN && pw_big_ids_warning && id > USHRT_MAX) {
warnx("%s > recommended max uid value (%u)", p, USHRT_MAX);
/*return (0);*/ /* THIS SHOULD NOT BE FATAL! */
}
pw->pw_uid = id;
if (!(p = strsep(&bp, ":"))) /* gid */
goto fmt;
if (p[0])
pw->pw_fields |= _PWF_GID;
else {
if (pw->pw_name[0] != '+' && pw->pw_name[0] != '-') {
if (flags & _PWSCAN_WARN)
warnx("no gid for user %s", pw->pw_name);
return (0);
}
}
errno = 0;
temp = strtoul(p, &ep, 10);
if ((temp == ULONG_MAX && errno == ERANGE) || temp > GID_MAX) {
if (flags & _PWSCAN_WARN)
warnx("%s > max gid value (%u)", p, GID_MAX);
return (0);
}
id = temp;
if (*ep != '\0') {
if (flags & _PWSCAN_WARN)
warnx("%s gid is incorrect", p);
return (0);
}
if (flags & _PWSCAN_WARN && pw_big_ids_warning && id > USHRT_MAX) {
warnx("%s > recommended max gid value (%u)", p, USHRT_MAX);
/* return (0); This should not be fatal! */
}
pw->pw_gid = id;
if (flags & _PWSCAN_MASTER ) {
if (!(pw->pw_class = strsep(&bp, ":"))) /* class */
goto fmt;
if (pw->pw_class[0])
pw->pw_fields |= _PWF_CLASS;
if (!(p = strsep(&bp, ":"))) /* change */
goto fmt;
if (p[0])
pw->pw_fields |= _PWF_CHANGE;
pw->pw_change = atol(p);
if (!(p = strsep(&bp, ":"))) /* expire */
goto fmt;
if (p[0])
pw->pw_fields |= _PWF_EXPIRE;
pw->pw_expire = atol(p);
}
if (!(pw->pw_gecos = strsep(&bp, ":"))) /* gecos */
goto fmt;
if (pw->pw_gecos[0])
pw->pw_fields |= _PWF_GECOS;
if (!(pw->pw_dir = strsep(&bp, ":"))) /* directory */
goto fmt;
if (pw->pw_dir[0])
pw->pw_fields |= _PWF_DIR;
if (!(pw->pw_shell = strsep(&bp, ":"))) /* shell */
goto fmt;
p = pw->pw_shell;
if (root && *p) { /* empty == /bin/sh */
for (setusershell();;) {
if (!(sh = getusershell())) {
if (flags & _PWSCAN_WARN)
warnx("warning, unknown root shell");
break;
}
if (!strcmp(p, sh))
break;
}
endusershell();
}
if (p[0])
pw->pw_fields |= _PWF_SHELL;
if ((p = strsep(&bp, ":"))) { /* too many */
fmt:
if (flags & _PWSCAN_WARN)
warnx("corrupted entry");
return (0);
}
return (1);
}
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