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glibc/resolv/res_init.c
Joseph Myers a3708cf6b0 Avoid use of atoi in some places in libc 
This patch is split out of
<https://sourceware.org/pipermail/libc-alpha/2022-December/144122.html>.

atoi has undefined behavior on out-of-range input, which makes it
problematic to use anywhere in glibc that might be processing input
out-of-range for atoi but not specified to produce undefined behavior
for the function calling atoi.  Change some uses of atoi to call
strtol instead; this avoids the undefined behavior, though there is no
guarantee that the overflow handling of strtol is really right in
those places either.  This also serves to avoid localplt test failures
given an installed header redirection for strtol (which means that the
call from the inline atoi implementation doesn't end up at a hidden
alias from libc_hidden_proto).

Certainly, the use of atoi is questionable in argp-help.c (shared with
gnulib, so shouldn't depend on glibc implementation details, and
processing user-provided input), and maybe also in argp-parse.c (I'm
not sure what that code in argp-parse.c is meant to be used for).  I
also changed inet/rexec.c and resolv/res_init.c similarly to use
strtol to avoid such localplt failures, although given those files (in
those versions) are only used in glibc it's not problematic for them
to rely on the specific behavior of glibc's atoi on out-of-range input
(in the absence of compiler optimizations based on the undefined
behavior) in the same way it's problematic for gnulib code to do so.

There may be other uses of atoi (or atol or atoll), in any of glibc's
installed code, for which it would also be appropriate to avoid the
undefined behavior on out-of-range input; this patch only fixes the
specific cases needed to avoid localplt failures.

Tested for x86_64.
2022-12-19 14:45:44 +00:00

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/* Resolver state initialization and resolv.conf parsing.
Copyright (C) 1995-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/*
* Copyright (c) 1985, 1989, 1993
* 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.
* 4. 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.
*/
/*
* Portions Copyright (c) 1993 by Digital Equipment Corporation.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies, and that
* the name of Digital Equipment Corporation not be used in advertising or
* publicity pertaining to distribution of the document or software without
* specific, written prior permission.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
* WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
* CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
*/
/*
* Portions Copyright (c) 1996-1999 by Internet Software Consortium.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
*/
#include <ctype.h>
#include <netdb.h>
#include <resolv/resolv-internal.h>
#include <res_hconf.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <net/if.h>
#include <netinet/in.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <inet/net-internal.h>
#include <errno.h>
#include <resolv_conf.h>
#include <file_change_detection.h>
static uint32_t net_mask (struct in_addr);
int
res_ninit (res_state statp)
{
return __res_vinit (statp, 0);
}
libc_hidden_def (__res_ninit)
/* Return true if CH separates the netmask in the "sortlist"
directive. */
static inline bool
is_sort_mask (char ch)
{
return ch == '/' || ch == '&';
}
/* Array of name server addresses. */
#define DYNARRAY_STRUCT nameserver_list
#define DYNARRAY_ELEMENT const struct sockaddr *
#define DYNARRAY_ELEMENT_FREE(e) free ((struct sockaddr *) *(e))
#define DYNARRAY_INITIAL_SIZE 3
#define DYNARRAY_PREFIX nameserver_list_
#include <malloc/dynarray-skeleton.c>
/* Array of strings for the search array. The backing store is
managed separately. */
#define DYNARRAY_STRUCT search_list
#define DYNARRAY_ELEMENT const char *
#define DYNARRAY_INITIAL_SIZE 6
#define DYNARRAY_PREFIX search_list_
#include <malloc/dynarray-skeleton.c>
/* Array of name server addresses. */
#define DYNARRAY_STRUCT sort_list
#define DYNARRAY_ELEMENT struct resolv_sortlist_entry
#define DYNARRAY_INITIAL_SIZE 0
#define DYNARRAY_PREFIX sort_list_
#include <malloc/dynarray-skeleton.c>
/* resolv.conf parser state and results. */
struct resolv_conf_parser
{
char *buffer; /* Temporary buffer for reading lines. */
struct nameserver_list nameserver_list; /* Nameserver addresses. */
char *search_list_store; /* Backing storage for search list entries. */
struct search_list search_list; /* Points into search_list_store. */
struct sort_list sort_list; /* Address preference sorting list. */
/* Configuration template. The non-array elements are filled in
directly. The array elements are updated prior to the call to
__resolv_conf_attach. */
struct resolv_conf template;
};
/* Return true if *PREINIT contains actual preinitialization. */
static bool
has_preinit_values (const struct __res_state *preinit)
{
return (preinit->retrans != 0 && preinit->retrans != RES_TIMEOUT)
|| (preinit->retry != 0 && preinit->retry != RES_DFLRETRY)
|| (preinit->options != 0
&& (preinit->options & ~RES_INIT) != RES_DEFAULT);
}
static void
resolv_conf_parser_init (struct resolv_conf_parser *parser,
const struct __res_state *preinit)
{
parser->buffer = NULL;
parser->search_list_store = NULL;
nameserver_list_init (&parser->nameserver_list);
search_list_init (&parser->search_list);
sort_list_init (&parser->sort_list);
if (preinit != NULL)
{
parser->template.retrans = preinit->retrans;
parser->template.retry = preinit->retry;
parser->template.options = preinit->options | RES_INIT;
}
else
{
parser->template.retrans = RES_TIMEOUT;
parser->template.retry = RES_DFLRETRY;
parser->template.options = RES_DEFAULT | RES_INIT;
}
parser->template.ndots = 1;
}
static void
resolv_conf_parser_free (struct resolv_conf_parser *parser)
{
free (parser->buffer);
free (parser->search_list_store);
nameserver_list_free (&parser->nameserver_list);
search_list_free (&parser->search_list);
sort_list_free (&parser->sort_list);
}
/* Allocate a struct sockaddr_in object on the heap, with the
specified address and port. */
static struct sockaddr *
allocate_address_v4 (struct in_addr a, uint16_t port)
{
struct sockaddr_in *sa4 = malloc (sizeof (*sa4));
if (sa4 == NULL)
return NULL;
sa4->sin_family = AF_INET;
sa4->sin_addr = a;
sa4->sin_port = htons (port);
return (struct sockaddr *) sa4;
}
/* Try to obtain the domain name from the host name and store it in
*RESULT. Return false on memory allocation failure. If the domain
name cannot be determined for any other reason, write NULL to
*RESULT and return true. */
static bool
domain_from_hostname (char **result)
{
char buf[256];
/* gethostbyname may not terminate the buffer. */
buf[sizeof (buf) - 1] = '\0';
if (__gethostname (buf, sizeof (buf) - 1) == 0)
{
char *dot = strchr (buf, '.');
if (dot != NULL)
{
*result = __strdup (dot + 1);
if (*result == NULL)
return false;
return true;
}
}
*result = NULL;
return true;
}
static void res_setoptions (struct resolv_conf_parser *, const char *options);
/* Internal helper function for __res_vinit, to aid with resource
deallocation and error handling. Return true on success, false on
failure. */
static bool
res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
{
char *cp;
size_t buffer_size = 0;
bool haveenv = false;
/* Allow user to override the local domain definition. */
if ((cp = getenv ("LOCALDOMAIN")) != NULL)
{
/* The code below splits the string in place. */
cp = __strdup (cp);
if (cp == NULL)
return false;
free (parser->search_list_store);
parser->search_list_store = cp;
haveenv = true;
/* The string will be truncated as needed below. */
search_list_add (&parser->search_list, cp);
/* Set search list to be blank-separated strings from rest of
env value. Permits users of LOCALDOMAIN to still have a
search list, and anyone to set the one that they want to use
as an individual (even more important now that the rfc1535
stuff restricts searches). */
for (bool in_name = true; *cp != '\0'; cp++)
{
if (*cp == '\n')
{
*cp = '\0';
break;
}
else if (*cp == ' ' || *cp == '\t')
{
*cp = '\0';
in_name = false;
}
else if (!in_name)
{
search_list_add (&parser->search_list, cp);
in_name = true;
}
}
}
#define MATCH(line, name) \
(!strncmp ((line), name, sizeof (name) - 1) \
&& ((line)[sizeof (name) - 1] == ' ' \
|| (line)[sizeof (name) - 1] == '\t'))
if (fp != NULL)
{
/* No threads use this stream. */
__fsetlocking (fp, FSETLOCKING_BYCALLER);
/* Read the config file. */
while (true)
{
{
ssize_t ret = __getline (&parser->buffer, &buffer_size, fp);
if (ret <= 0)
{
if (_IO_ferror_unlocked (fp))
return false;
else
break;
}
}
/* Skip comments. */
if (*parser->buffer == ';' || *parser->buffer == '#')
continue;
/* Read default domain name. */
if (MATCH (parser->buffer, "domain"))
{
if (haveenv)
/* LOCALDOMAIN overrides the configuration file. */
continue;
cp = parser->buffer + sizeof ("domain") - 1;
while (*cp == ' ' || *cp == '\t')
cp++;
if ((*cp == '\0') || (*cp == '\n'))
continue;
cp = __strdup (cp);
if (cp == NULL)
return false;
free (parser->search_list_store);
parser->search_list_store = cp;
search_list_clear (&parser->search_list);
search_list_add (&parser->search_list, cp);
/* Replace trailing whitespace. */
if ((cp = strpbrk (cp, " \t\n")) != NULL)
*cp = '\0';
continue;
}
/* Set search list. */
if (MATCH (parser->buffer, "search"))
{
if (haveenv)
/* LOCALDOMAIN overrides the configuration file. */
continue;
cp = parser->buffer + sizeof ("search") - 1;
while (*cp == ' ' || *cp == '\t')
cp++;
if ((*cp == '\0') || (*cp == '\n'))
continue;
{
char *p = strchr (cp, '\n');
if (p != NULL)
*p = '\0';
}
cp = __strdup (cp);
if (cp == NULL)
return false;
free (parser->search_list_store);
parser->search_list_store = cp;
/* The string is truncated below. */
search_list_clear (&parser->search_list);
search_list_add (&parser->search_list, cp);
/* Set search list to be blank-separated strings on rest
of line. */
for (bool in_name = true; *cp != '\0'; cp++)
{
if (*cp == ' ' || *cp == '\t')
{
*cp = '\0';
in_name = false;
}
else if (!in_name)
{
search_list_add (&parser->search_list, cp);
in_name = true;
}
}
continue;
}
/* Read nameservers to query. */
if (MATCH (parser->buffer, "nameserver"))
{
struct in_addr a;
cp = parser->buffer + sizeof ("nameserver") - 1;
while (*cp == ' ' || *cp == '\t')
cp++;
/* Ignore trailing contents on the name server line. */
{
char *el;
if ((el = strpbrk (cp, " \t\n")) != NULL)
*el = '\0';
}
struct sockaddr *sa;
if ((*cp != '\0') && (*cp != '\n') && __inet_aton_exact (cp, &a))
{
sa = allocate_address_v4 (a, NAMESERVER_PORT);
if (sa == NULL)
return false;
}
else
{
struct in6_addr a6;
char *el;
if ((el = strchr (cp, SCOPE_DELIMITER)) != NULL)
*el = '\0';
if ((*cp != '\0') && (__inet_pton (AF_INET6, cp, &a6) > 0))
{
struct sockaddr_in6 *sa6;
sa6 = malloc (sizeof (*sa6));
if (sa6 == NULL)
return false;
sa6->sin6_family = AF_INET6;
sa6->sin6_port = htons (NAMESERVER_PORT);
sa6->sin6_flowinfo = 0;
sa6->sin6_addr = a6;
sa6->sin6_scope_id = 0;
if (__glibc_likely (el != NULL))
/* Ignore errors, for backwards
compatibility. */
__inet6_scopeid_pton
(&a6, el + 1, &sa6->sin6_scope_id);
sa = (struct sockaddr *) sa6;
}
else
/* IPv6 address parse failure. */
sa = NULL;
}
if (sa != NULL)
{
const struct sockaddr **p = nameserver_list_emplace
(&parser->nameserver_list);
if (p != NULL)
*p = sa;
else
{
free (sa);
return false;
}
}
continue;
}
if (MATCH (parser->buffer, "sortlist"))
{
struct in_addr a;
cp = parser->buffer + sizeof ("sortlist") - 1;
while (true)
{
while (*cp == ' ' || *cp == '\t')
cp++;
if (*cp == '\0' || *cp == '\n' || *cp == ';')
break;
char *net = cp;
while (*cp && !is_sort_mask (*cp) && *cp != ';'
&& isascii (*cp) && !isspace (*cp))
cp++;
char separator = *cp;
*cp = 0;
struct resolv_sortlist_entry e;
if (__inet_aton_exact (net, &a))
{
e.addr = a;
if (is_sort_mask (separator))
{
*cp++ = separator;
net = cp;
while (*cp && *cp != ';'
&& isascii (*cp) && !isspace (*cp))
cp++;
separator = *cp;
*cp = 0;
if (__inet_aton_exact (net, &a))
e.mask = a.s_addr;
else
e.mask = net_mask (e.addr);
}
else
e.mask = net_mask (e.addr);
sort_list_add (&parser->sort_list, e);
}
*cp = separator;
}
continue;
}
if (MATCH (parser->buffer, "options"))
{
res_setoptions (parser, parser->buffer + sizeof ("options") - 1);
continue;
}
}
}
if (__glibc_unlikely (nameserver_list_size (&parser->nameserver_list) == 0))
{
const struct sockaddr **p
= nameserver_list_emplace (&parser->nameserver_list);
if (p == NULL)
return false;
*p = allocate_address_v4 (__inet_makeaddr (IN_LOOPBACKNET, 1),
NAMESERVER_PORT);
if (*p == NULL)
return false;
}
if (search_list_size (&parser->search_list) == 0)
{
char *domain;
if (!domain_from_hostname (&domain))
return false;
if (domain != NULL)
{
free (parser->search_list_store);
parser->search_list_store = domain;
search_list_add (&parser->search_list, domain);
}
}
if ((cp = getenv ("RES_OPTIONS")) != NULL)
res_setoptions (parser, cp);
if (nameserver_list_has_failed (&parser->nameserver_list)
|| search_list_has_failed (&parser->search_list)
|| sort_list_has_failed (&parser->sort_list))
{
__set_errno (ENOMEM);
return false;
}
return true;
}
struct resolv_conf *
__resolv_conf_load (struct __res_state *preinit,
struct file_change_detection *change)
{
/* Ensure that /etc/hosts.conf has been loaded (once). */
_res_hconf_init ();
FILE *fp = fopen (_PATH_RESCONF, "rce");
if (fp == NULL)
switch (errno)
{
case EACCES:
case EISDIR:
case ELOOP:
case ENOENT:
case ENOTDIR:
case EPERM:
/* Ignore these errors. They are persistent errors caused
by file system contents. */
break;
default:
/* Other errors refer to resource allocation problems and
need to be handled by the application. */
return NULL;
}
struct resolv_conf_parser parser;
resolv_conf_parser_init (&parser, preinit);
struct resolv_conf *conf = NULL;
bool ok = res_vinit_1 (fp, &parser);
if (ok && change != NULL)
/* Update the file change information if the configuration was
loaded successfully. */
ok = __file_change_detection_for_fp (change, fp);
if (ok)
{
parser.template.nameserver_list
= nameserver_list_begin (&parser.nameserver_list);
parser.template.nameserver_list_size
= nameserver_list_size (&parser.nameserver_list);
parser.template.search_list = search_list_begin (&parser.search_list);
parser.template.search_list_size
= search_list_size (&parser.search_list);
parser.template.sort_list = sort_list_begin (&parser.sort_list);
parser.template.sort_list_size = sort_list_size (&parser.sort_list);
conf = __resolv_conf_allocate (&parser.template);
}
resolv_conf_parser_free (&parser);
if (fp != NULL)
{
int saved_errno = errno;
fclose (fp);
__set_errno (saved_errno);
}
return conf;
}
/* Set up default settings. If the /etc/resolv.conf configuration
file exist, the values there will have precedence. Otherwise, the
server address is set to INADDR_LOOPBACK and the default domain
name comes from gethostname. The RES_OPTIONS and LOCALDOMAIN
environment variables can be used to override some settings.
Return 0 if completes successfully, -1 on error. */
int
__res_vinit (res_state statp, int preinit)
{
struct resolv_conf *conf;
if (preinit && has_preinit_values (statp))
/* For the preinit case, we cannot use the cached configuration
because some settings could be different. */
conf = __resolv_conf_load (statp, NULL);
else
conf = __resolv_conf_get_current ();
if (conf == NULL)
return -1;
bool ok = __resolv_conf_attach (statp, conf);
__resolv_conf_put (conf);
if (ok)
{
if (preinit)
statp->id = res_randomid ();
return 0;
}
else
return -1;
}
static void
res_setoptions (struct resolv_conf_parser *parser, const char *options)
{
const char *cp = options;
while (*cp)
{
/* Skip leading and inner runs of spaces. */
while (*cp == ' ' || *cp == '\t')
cp++;
/* Search for and process individual options. */
if (!strncmp (cp, "ndots:", sizeof ("ndots:") - 1))
{
int i = strtol (cp + sizeof ("ndots:") - 1, NULL, 10);
if (i <= RES_MAXNDOTS)
parser->template.ndots = i;
else
parser->template.ndots = RES_MAXNDOTS;
}
else if (!strncmp (cp, "timeout:", sizeof ("timeout:") - 1))
{
int i = strtol (cp + sizeof ("timeout:") - 1, NULL, 10);
if (i <= RES_MAXRETRANS)
parser->template.retrans = i;
else
parser->template.retrans = RES_MAXRETRANS;
}
else if (!strncmp (cp, "attempts:", sizeof ("attempts:") - 1))
{
int i = strtol (cp + sizeof ("attempts:") - 1, NULL, 10);
if (i <= RES_MAXRETRY)
parser->template.retry = i;
else
parser->template.retry = RES_MAXRETRY;
}
else
{
static const struct
{
char str[22];
uint8_t len;
uint8_t clear;
unsigned long int flag;
} options[] = {
#define STRnLEN(str) str, sizeof (str) - 1
{ STRnLEN ("rotate"), 0, RES_ROTATE },
{ STRnLEN ("edns0"), 0, RES_USE_EDNS0 },
{ STRnLEN ("single-request-reopen"), 0, RES_SNGLKUPREOP },
{ STRnLEN ("single-request"), 0, RES_SNGLKUP },
{ STRnLEN ("no_tld_query"), 0, RES_NOTLDQUERY },
{ STRnLEN ("no-tld-query"), 0, RES_NOTLDQUERY },
{ STRnLEN ("no-reload"), 0, RES_NORELOAD },
{ STRnLEN ("use-vc"), 0, RES_USEVC },
{ STRnLEN ("trust-ad"), 0, RES_TRUSTAD },
{ STRnLEN ("no-aaaa"), 0, RES_NOAAAA },
};
#define noptions (sizeof (options) / sizeof (options[0]))
for (int i = 0; i < noptions; ++i)
if (strncmp (cp, options[i].str, options[i].len) == 0)
{
if (options[i].clear)
parser->template.options &= options[i].flag;
else
parser->template.options |= options[i].flag;
break;
}
}
/* Skip to next run of spaces. */
while (*cp && *cp != ' ' && *cp != '\t')
cp++;
}
}
static uint32_t
net_mask (struct in_addr in)
{
uint32_t i = ntohl (in.s_addr);
if (IN_CLASSA (i))
return htonl (IN_CLASSA_NET);
else if (IN_CLASSB (i))
return htonl (IN_CLASSB_NET);
return htonl (IN_CLASSC_NET);
}
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