glibc/nscd/nscd_getpw_r.c
Jakub Jelinek cfe1fc1013 Robustify libc-side nscd database reader.
The nscd database mapped in processes can change at any time.  We
have to be more vigilant when it comes to using that memory.  Test
the data entries are valid in their entire size, don't read data
again from memory once we verified it, and make sure the trailing
pointer is not going off the deep end.
2009-05-15 21:17:08 -07:00

244 lines
6.5 KiB
C

/* Copyright (C) 1998, 1999, 2003, 2004, 2005, 2007, 2009
Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Thorsten Kukuk <kukuk@uni-paderborn.de>, 1998.
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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <assert.h>
#include <errno.h>
#include <pwd.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <not-cancel.h>
#include <stdio-common/_itoa.h>
#include "nscd-client.h"
#include "nscd_proto.h"
int __nss_not_use_nscd_passwd;
static int nscd_getpw_r (const char *key, size_t keylen, request_type type,
struct passwd *resultbuf, char *buffer,
size_t buflen, struct passwd **result)
internal_function;
int
__nscd_getpwnam_r (const char *name, struct passwd *resultbuf, char *buffer,
size_t buflen, struct passwd **result)
{
if (name == NULL)
return -1;
return nscd_getpw_r (name, strlen (name) + 1, GETPWBYNAME, resultbuf,
buffer, buflen, result);
}
int
__nscd_getpwuid_r (uid_t uid, struct passwd *resultbuf, char *buffer,
size_t buflen, struct passwd **result)
{
char buf[3 * sizeof (uid_t)];
buf[sizeof (buf) - 1] = '\0';
char *cp = _itoa_word (uid, buf + sizeof (buf) - 1, 10, 0);
return nscd_getpw_r (cp, buf + sizeof (buf) - cp, GETPWBYUID, resultbuf,
buffer, buflen, result);
}
libc_locked_map_ptr (static, map_handle);
/* Note that we only free the structure if necessary. The memory
mapping is not removed since it is not visible to the malloc
handling. */
libc_freeres_fn (pw_map_free)
{
if (map_handle.mapped != NO_MAPPING)
{
void *p = map_handle.mapped;
map_handle.mapped = NO_MAPPING;
free (p);
}
}
static int
internal_function
nscd_getpw_r (const char *key, size_t keylen, request_type type,
struct passwd *resultbuf, char *buffer, size_t buflen,
struct passwd **result)
{
int gc_cycle;
int nretries = 0;
/* If the mapping is available, try to search there instead of
communicating with the nscd. */
struct mapped_database *mapped;
mapped = __nscd_get_map_ref (GETFDPW, "passwd", &map_handle, &gc_cycle);
retry:;
const char *pw_name = NULL;
int retval = -1;
const char *recend = (const char *) ~UINTMAX_C (0);
pw_response_header pw_resp;
if (mapped != NO_MAPPING)
{
struct datahead *found = __nscd_cache_search (type, key, keylen, mapped,
sizeof pw_resp);
if (found != NULL)
{
pw_name = (const char *) (&found->data[0].pwdata + 1);
pw_resp = found->data[0].pwdata;
recend = (const char *) found->data + found->recsize;
/* Now check if we can trust pw_resp fields. If GC is
in progress, it can contain anything. */
if (mapped->head->gc_cycle != gc_cycle)
{
retval = -2;
goto out;
}
}
}
int sock = -1;
if (pw_name == NULL)
{
sock = __nscd_open_socket (key, keylen, type, &pw_resp,
sizeof (pw_resp));
if (sock == -1)
{
__nss_not_use_nscd_passwd = 1;
goto out;
}
}
/* No value found so far. */
*result = NULL;
if (__builtin_expect (pw_resp.found == -1, 0))
{
/* The daemon does not cache this database. */
__nss_not_use_nscd_passwd = 1;
goto out_close;
}
if (pw_resp.found == 1)
{
/* Set the information we already have. */
resultbuf->pw_uid = pw_resp.pw_uid;
resultbuf->pw_gid = pw_resp.pw_gid;
char *p = buffer;
/* get pw_name */
resultbuf->pw_name = p;
p += pw_resp.pw_name_len;
/* get pw_passwd */
resultbuf->pw_passwd = p;
p += pw_resp.pw_passwd_len;
/* get pw_gecos */
resultbuf->pw_gecos = p;
p += pw_resp.pw_gecos_len;
/* get pw_dir */
resultbuf->pw_dir = p;
p += pw_resp.pw_dir_len;
/* get pw_pshell */
resultbuf->pw_shell = p;
p += pw_resp.pw_shell_len;
ssize_t total = p - buffer;
if (__builtin_expect (pw_name + total > recend, 0))
goto out_close;
if (__builtin_expect (buflen < total, 0))
{
__set_errno (ERANGE);
retval = ERANGE;
goto out_close;
}
retval = 0;
if (pw_name == NULL)
{
ssize_t nbytes = __readall (sock, buffer, total);
if (__builtin_expect (nbytes != total, 0))
{
/* The `errno' to some value != ERANGE. */
__set_errno (ENOENT);
retval = ENOENT;
}
else
*result = resultbuf;
}
else
{
/* Copy the various strings. */
memcpy (resultbuf->pw_name, pw_name, total);
/* Try to detect corrupt databases. */
if (resultbuf->pw_name[pw_resp.pw_name_len - 1] != '\0'
|| resultbuf->pw_passwd[pw_resp.pw_passwd_len - 1] != '\0'
|| resultbuf->pw_gecos[pw_resp.pw_gecos_len - 1] != '\0'
|| resultbuf->pw_dir[pw_resp.pw_dir_len - 1] != '\0'
|| resultbuf->pw_shell[pw_resp.pw_shell_len - 1] != '\0')
{
/* We cannot use the database. */
retval = mapped->head->gc_cycle != gc_cycle ? -2 : -1;
goto out_close;
}
*result = resultbuf;
}
}
else
{
/* Set errno to 0 to indicate no error, just no found record. */
__set_errno (0);
/* Even though we have not found anything, the result is zero. */
retval = 0;
}
out_close:
if (sock != -1)
close_not_cancel_no_status (sock);
out:
if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
{
/* When we come here this means there has been a GC cycle while we
were looking for the data. This means the data might have been
inconsistent. Retry if possible. */
if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
{
/* nscd is just running gc now. Disable using the mapping. */
if (atomic_decrement_val (&mapped->counter) == 0)
__nscd_unmap (mapped);
mapped = NO_MAPPING;
}
if (retval != -1)
goto retry;
}
return retval;
}