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31d0a4fa64
When get*ent is called without a preceding set*ent, we need to set the initial iteration position in get*ent. Reproducer: Add “services: db files” to /etc/nsswitch.conf, then run “perl -e getservent”. It will segfault before this change, and exit silently after it.
312 lines
8.8 KiB
C
312 lines
8.8 KiB
C
/* Common code for DB-based databases in nss_db module.
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Copyright (C) 1996-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <dlfcn.h>
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#include <fcntl.h>
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#include <stdint.h>
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#include <sys/mman.h>
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#include <libc-lock.h>
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#include "nsswitch.h"
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#include "nss_db.h"
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/* The hashing function we use. */
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#include "../intl/hash-string.h"
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/* These symbols are defined by the including source file:
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ENTNAME -- database name of the structure and functions (hostent, pwent).
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STRUCTURE -- struct name, define only if not ENTNAME (passwd, group).
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DATABASE -- database file name, ("hosts", "passwd")
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NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.
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*/
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#define ENTNAME_r CONCAT(ENTNAME,_r)
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#include <paths.h>
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#define DBFILE _PATH_VARDB DATABASE ".db"
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#ifdef NEED_H_ERRNO
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# define H_ERRNO_PROTO , int *herrnop
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# define H_ERRNO_ARG , herrnop
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# define H_ERRNO_SET(val) (*herrnop = (val))
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#else
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# define H_ERRNO_PROTO
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# define H_ERRNO_ARG
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# define H_ERRNO_SET(val) ((void) 0)
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#endif
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/* State for this database. */
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static struct nss_db_map state;
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/* Lock to protect the state and global variables. */
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__libc_lock_define (static , lock);
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/* Maintenance of the shared handle open on the database. */
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static int keep_db;
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static const char *entidx;
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/* Open the database. */
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enum nss_status
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CONCAT(_nss_db_set,ENTNAME) (int stayopen)
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{
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enum nss_status status;
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__libc_lock_lock (lock);
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status = internal_setent (DBFILE, &state);
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if (status == NSS_STATUS_SUCCESS)
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{
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/* Remember STAYOPEN flag. */
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keep_db |= stayopen;
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/* Reset the sequential index. */
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entidx = NULL;
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}
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__libc_lock_unlock (lock);
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return status;
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}
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/* Close it again. */
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enum nss_status
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CONCAT(_nss_db_end,ENTNAME) (void)
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{
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__libc_lock_lock (lock);
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internal_endent (&state);
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/* Reset STAYOPEN flag. */
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keep_db = 0;
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__libc_lock_unlock (lock);
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return NSS_STATUS_SUCCESS;
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}
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/* Macro for defining lookup functions for this DB-based database.
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NAME is the name of the lookup; e.g. `pwnam'.
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DB_CHAR is index indicator for the database.
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KEYPATTERN gives `printf' args to construct a key string;
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e.g. `("%d", id)'.
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KEYSIZE gives the allocation size of a buffer to construct it in;
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e.g. `1 + sizeof (id) * 4'.
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PROTO is the potentially empty list of other parameters.
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BREAK_IF_MATCH is a block of code which compares `struct STRUCTURE *result'
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to the lookup key arguments and does `break;' if they match. */
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#define DB_LOOKUP(name, db_char, keysize, keypattern, break_if_match, proto...)\
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enum nss_status \
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_nss_db_get##name##_r (proto, struct STRUCTURE *result, \
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char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO)\
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{ \
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struct parser_data *data = (void *) buffer; \
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\
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if (buflen < sizeof *data) \
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{ \
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*errnop = ERANGE; \
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H_ERRNO_SET (NETDB_INTERNAL); \
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return NSS_STATUS_TRYAGAIN; \
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} \
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\
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struct nss_db_map state = { NULL, 0 }; \
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enum nss_status status = internal_setent (DBFILE, &state); \
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if (status != NSS_STATUS_SUCCESS) \
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{ \
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*errnop = errno; \
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H_ERRNO_SET (NETDB_INTERNAL); \
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return status; \
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} \
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\
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const struct nss_db_header *header = state.header; \
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int i; \
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for (i = 0; i < header->ndbs; ++i) \
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if (header->dbs[i].id == db_char) \
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break; \
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if (i == header->ndbs) \
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{ \
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status = NSS_STATUS_UNAVAIL; \
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goto out; \
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} \
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\
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char *key; \
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if (db_char == '.') \
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key = (char *) IGNOREPATTERN keypattern; \
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else \
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{ \
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const size_t size = (keysize) + 1; \
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key = alloca (size); \
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\
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KEYPRINTF keypattern; \
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} \
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\
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const stridx_t *hashtable \
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= (const stridx_t *) ((const char *) header \
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+ header->dbs[i].hashoffset); \
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const char *valstrtab = (const char *) header + header->valstroffset; \
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uint32_t hashval = __hash_string (key); \
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size_t hidx = hashval % header->dbs[i].hashsize; \
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size_t hval2 = 1 + hashval % (header->dbs[i].hashsize - 2); \
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\
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status = NSS_STATUS_NOTFOUND; \
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while (hashtable[hidx] != ~((stridx_t) 0)) \
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{ \
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const char *valstr = valstrtab + hashtable[hidx]; \
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size_t len = strlen (valstr) + 1; \
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if (len > buflen) \
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{ \
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/* No room to copy the data to. */ \
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*errnop = ERANGE; \
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H_ERRNO_SET (NETDB_INTERNAL); \
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status = NSS_STATUS_TRYAGAIN; \
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break; \
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} \
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\
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/* Copy the string to a place where it can be modified. */ \
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char *p = memcpy (buffer, valstr, len); \
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\
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int err = parse_line (p, result, data, buflen, errnop EXTRA_ARGS); \
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\
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/* Advance before break_if_match, lest it uses continue to skip
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to the next entry. */ \
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if ((hidx += hval2) >= header->dbs[i].hashsize) \
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hidx -= header->dbs[i].hashsize; \
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\
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if (err > 0) \
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{ \
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status = NSS_STATUS_SUCCESS; \
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break_if_match; \
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status = NSS_STATUS_NOTFOUND; \
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} \
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else if (err == -1) \
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{ \
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H_ERRNO_SET (NETDB_INTERNAL); \
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status = NSS_STATUS_TRYAGAIN; \
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break; \
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} \
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} \
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\
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if (status == NSS_STATUS_NOTFOUND) \
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H_ERRNO_SET (HOST_NOT_FOUND); \
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\
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out: \
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internal_endent (&state); \
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\
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return status; \
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}
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#define KEYPRINTF(pattern, args...) snprintf (key, size, pattern ,##args)
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#define IGNOREPATTERN(pattern, arg1, args...) (char *) (uintptr_t) arg1
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/* Return the next entry from the database file, doing locking. */
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enum nss_status
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CONCAT(_nss_db_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
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size_t buflen, int *errnop H_ERRNO_PROTO)
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{
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/* Return next entry in host file. */
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enum nss_status status;
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struct parser_data *data = (void *) buffer;
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if (buflen < sizeof *data)
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{
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*errnop = ERANGE;
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H_ERRNO_SET (NETDB_INTERNAL);
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return NSS_STATUS_TRYAGAIN;
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}
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__libc_lock_lock (lock);
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if (state.header == NULL)
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{
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status = internal_setent (DBFILE, &state);
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if (status != NSS_STATUS_SUCCESS)
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{
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*errnop = errno;
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H_ERRNO_SET (NETDB_INTERNAL);
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goto out;
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}
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entidx = NULL;
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}
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/* Start from the beginning if freshly initialized or reset
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requested by set*ent. */
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if (entidx == NULL)
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entidx = (const char *) state.header + state.header->valstroffset;
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status = NSS_STATUS_UNAVAIL;
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if (state.header != MAP_FAILED)
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{
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const char *const end = ((const char *) state.header
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+ state.header->valstroffset
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+ state.header->valstrlen);
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while (entidx < end)
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{
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const char *next = rawmemchr (entidx, '\0') + 1;
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size_t len = next - entidx;
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if (len > buflen)
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{
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/* No room to copy the data to. */
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*errnop = ERANGE;
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H_ERRNO_SET (NETDB_INTERNAL);
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status = NSS_STATUS_TRYAGAIN;
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break;
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}
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/* Copy the string to a place where it can be modified. */
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char *p = memcpy (buffer, entidx, len);
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int err = parse_line (p, result, data, buflen, errnop EXTRA_ARGS);
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if (err > 0)
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{
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status = NSS_STATUS_SUCCESS;
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entidx = next;
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break;
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}
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if (err < 0)
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{
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H_ERRNO_SET (NETDB_INTERNAL);
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status = NSS_STATUS_TRYAGAIN;
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break;
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}
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/* Continue with the next record, this one is ill-formed. */
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entidx = next;
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}
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}
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out:
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__libc_lock_unlock (lock);
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return status;
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}
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