439 lines
12 KiB
C
439 lines
12 KiB
C
/* Cache handling for host lookup.
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Copyright (C) 2004-2006, 2008, 2009, 2011 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published
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by the Free Software Foundation; version 2 of the License, or
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(at your option) any later version.
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This program 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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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#include <assert.h>
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#include <errno.h>
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#include <grp.h>
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#include <libintl.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include "dbg_log.h"
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#include "nscd.h"
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#ifdef HAVE_SENDFILE
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# include <kernel-features.h>
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#endif
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#include "../nss/nsswitch.h"
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/* Type of the lookup function. */
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typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t,
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long int *, long int *,
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gid_t **, long int, int *);
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static const initgr_response_header notfound =
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{
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.version = NSCD_VERSION,
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.found = 0,
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.ngrps = 0
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};
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#include "../grp/compat-initgroups.c"
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static time_t
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addinitgroupsX (struct database_dyn *db, int fd, request_header *req,
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void *key, uid_t uid, struct hashentry *const he,
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struct datahead *dh)
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{
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/* Search for the entry matching the key. Please note that we don't
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look again in the table whether the dataset is now available. We
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simply insert it. It does not matter if it is in there twice. The
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pruning function only will look at the timestamp. */
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/* We allocate all data in one memory block: the iov vector,
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the response header and the dataset itself. */
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struct dataset
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{
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struct datahead head;
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initgr_response_header resp;
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char strdata[0];
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} *dataset = NULL;
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if (__builtin_expect (debug_level > 0, 0))
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{
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if (he == NULL)
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dbg_log (_("Haven't found \"%s\" in group cache!"), (char *) key);
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else
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dbg_log (_("Reloading \"%s\" in group cache!"), (char *) key);
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}
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static service_user *group_database;
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service_user *nip = NULL;
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int no_more;
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if (group_database != NULL)
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{
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nip = group_database;
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no_more = 0;
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}
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else
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no_more = __nss_database_lookup ("group", NULL,
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"compat [NOTFOUND=return] files", &nip);
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/* We always use sysconf even if NGROUPS_MAX is defined. That way, the
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limit can be raised in the kernel configuration without having to
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recompile libc. */
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long int limit = __sysconf (_SC_NGROUPS_MAX);
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long int size;
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if (limit > 0)
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/* We limit the size of the intially allocated array. */
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size = MIN (limit, 64);
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else
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/* No fixed limit on groups. Pick a starting buffer size. */
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size = 16;
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long int start = 0;
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bool all_tryagain = true;
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bool any_success = false;
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/* This is temporary memory, we need not (and must not) call
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mempool_alloc. */
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// XXX This really should use alloca. need to change the backends.
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gid_t *groups = (gid_t *) malloc (size * sizeof (gid_t));
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if (__builtin_expect (groups == NULL, 0))
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/* No more memory. */
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goto out;
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/* Nothing added yet. */
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while (! no_more)
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{
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long int prev_start = start;
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enum nss_status status;
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initgroups_dyn_function fct;
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fct = __nss_lookup_function (nip, "initgroups_dyn");
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if (fct == NULL)
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{
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status = compat_call (nip, key, -1, &start, &size, &groups,
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limit, &errno);
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if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE)
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break;
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}
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else
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status = DL_CALL_FCT (fct, (key, -1, &start, &size, &groups,
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limit, &errno));
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/* Remove duplicates. */
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long int cnt = prev_start;
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while (cnt < start)
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{
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long int inner;
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for (inner = 0; inner < prev_start; ++inner)
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if (groups[inner] == groups[cnt])
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break;
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if (inner < prev_start)
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groups[cnt] = groups[--start];
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else
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++cnt;
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}
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if (status != NSS_STATUS_TRYAGAIN)
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all_tryagain = false;
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/* This is really only for debugging. */
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if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
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__libc_fatal ("illegal status in internal_getgrouplist");
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any_success |= status == NSS_STATUS_SUCCESS;
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if (status != NSS_STATUS_SUCCESS
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&& nss_next_action (nip, status) == NSS_ACTION_RETURN)
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break;
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if (nip->next == NULL)
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no_more = -1;
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else
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nip = nip->next;
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}
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ssize_t total;
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ssize_t written;
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time_t timeout;
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out:
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timeout = MAX_TIMEOUT_VALUE;
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if (!any_success)
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{
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/* Nothing found. Create a negative result record. */
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written = total = sizeof (notfound);
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if (he != NULL && all_tryagain)
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{
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/* If we have an old record available but cannot find one now
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because the service is not available we keep the old record
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and make sure it does not get removed. */
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if (reload_count != UINT_MAX && dh->nreloads == reload_count)
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/* Do not reset the value if we never not reload the record. */
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dh->nreloads = reload_count - 1;
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/* Reload with the same time-to-live value. */
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timeout = dh->timeout = time (NULL) + db->postimeout;
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}
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else
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{
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/* We have no data. This means we send the standard reply for this
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case. */
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if (fd != -1)
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written = TEMP_FAILURE_RETRY (send (fd, ¬found, total,
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MSG_NOSIGNAL));
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/* If we cannot permanently store the result, so be it. */
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if (__builtin_expect (db->negtimeout == 0, 0))
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{
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/* Mark the old entry as obsolete. */
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if (dh != NULL)
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dh->usable = false;
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}
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else if ((dataset = mempool_alloc (db, (sizeof (struct dataset)
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+ req->key_len), 1)) != NULL)
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{
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dataset->head.allocsize = sizeof (struct dataset) + req->key_len;
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dataset->head.recsize = total;
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dataset->head.notfound = true;
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dataset->head.nreloads = 0;
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dataset->head.usable = true;
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/* Compute the timeout time. */
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timeout = dataset->head.timeout = time (NULL) + db->negtimeout;
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/* This is the reply. */
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memcpy (&dataset->resp, ¬found, total);
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/* Copy the key data. */
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char *key_copy = memcpy (dataset->strdata, key, req->key_len);
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/* If necessary, we also propagate the data to disk. */
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if (db->persistent)
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{
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// XXX async OK?
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uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
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msync ((void *) pval,
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((uintptr_t) dataset & pagesize_m1)
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+ sizeof (struct dataset) + req->key_len, MS_ASYNC);
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}
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(void) cache_add (req->type, key_copy, req->key_len,
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&dataset->head, true, db, uid, he == NULL);
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pthread_rwlock_unlock (&db->lock);
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/* Mark the old entry as obsolete. */
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if (dh != NULL)
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dh->usable = false;
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}
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}
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}
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else
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{
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written = total = (offsetof (struct dataset, strdata)
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+ start * sizeof (int32_t));
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/* If we refill the cache, first assume the reconrd did not
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change. Allocate memory on the cache since it is likely
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discarded anyway. If it turns out to be necessary to have a
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new record we can still allocate real memory. */
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bool alloca_used = false;
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dataset = NULL;
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if (he == NULL)
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dataset = (struct dataset *) mempool_alloc (db, total + req->key_len,
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1);
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if (dataset == NULL)
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{
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/* We cannot permanently add the result in the moment. But
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we can provide the result as is. Store the data in some
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temporary memory. */
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dataset = (struct dataset *) alloca (total + req->key_len);
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/* We cannot add this record to the permanent database. */
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alloca_used = true;
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}
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dataset->head.allocsize = total + req->key_len;
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dataset->head.recsize = total - offsetof (struct dataset, resp);
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dataset->head.notfound = false;
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dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
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dataset->head.usable = true;
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/* Compute the timeout time. */
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timeout = dataset->head.timeout = time (NULL) + db->postimeout;
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dataset->resp.version = NSCD_VERSION;
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dataset->resp.found = 1;
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dataset->resp.ngrps = start;
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char *cp = dataset->strdata;
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/* Copy the GID values. If the size of the types match this is
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very simple. */
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if (sizeof (gid_t) == sizeof (int32_t))
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cp = mempcpy (cp, groups, start * sizeof (gid_t));
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else
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{
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gid_t *gcp = (gid_t *) cp;
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for (int i = 0; i < start; ++i)
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*gcp++ = groups[i];
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cp = (char *) gcp;
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}
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/* Finally the user name. */
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memcpy (cp, key, req->key_len);
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assert (cp == dataset->strdata + total - offsetof (struct dataset,
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strdata));
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/* Now we can determine whether on refill we have to create a new
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record or not. */
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if (he != NULL)
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{
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assert (fd == -1);
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if (total + req->key_len == dh->allocsize
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&& total - offsetof (struct dataset, resp) == dh->recsize
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&& memcmp (&dataset->resp, dh->data,
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dh->allocsize - offsetof (struct dataset, resp)) == 0)
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{
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/* The data has not changed. We will just bump the
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timeout value. Note that the new record has been
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allocated on the stack and need not be freed. */
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dh->timeout = dataset->head.timeout;
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++dh->nreloads;
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}
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else
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{
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/* We have to create a new record. Just allocate
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appropriate memory and copy it. */
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struct dataset *newp
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= (struct dataset *) mempool_alloc (db, total + req->key_len,
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1);
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if (newp != NULL)
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{
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/* Adjust pointer into the memory block. */
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cp = (char *) newp + (cp - (char *) dataset);
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dataset = memcpy (newp, dataset, total + req->key_len);
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alloca_used = false;
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}
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/* Mark the old record as obsolete. */
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dh->usable = false;
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}
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}
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else
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{
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/* We write the dataset before inserting it to the database
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since while inserting this thread might block and so would
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unnecessarily let the receiver wait. */
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assert (fd != -1);
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#ifdef HAVE_SENDFILE
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if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
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{
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assert (db->wr_fd != -1);
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assert ((char *) &dataset->resp > (char *) db->data);
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assert ((char *) dataset - (char *) db->head
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+ total
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<= (sizeof (struct database_pers_head)
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+ db->head->module * sizeof (ref_t)
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+ db->head->data_size));
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written = sendfileall (fd, db->wr_fd,
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(char *) &dataset->resp
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- (char *) db->head, dataset->head.recsize);
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# ifndef __ASSUME_SENDFILE
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if (written == -1 && errno == ENOSYS)
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goto use_write;
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# endif
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}
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else
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# ifndef __ASSUME_SENDFILE
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use_write:
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# endif
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#endif
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written = writeall (fd, &dataset->resp, dataset->head.recsize);
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}
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/* Add the record to the database. But only if it has not been
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stored on the stack. */
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if (! alloca_used)
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{
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/* If necessary, we also propagate the data to disk. */
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if (db->persistent)
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{
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// XXX async OK?
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uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
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msync ((void *) pval,
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((uintptr_t) dataset & pagesize_m1) + total +
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req->key_len, MS_ASYNC);
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}
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(void) cache_add (INITGROUPS, cp, req->key_len, &dataset->head, true,
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db, uid, he == NULL);
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pthread_rwlock_unlock (&db->lock);
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}
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}
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free (groups);
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if (__builtin_expect (written != total, 0) && debug_level > 0)
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{
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char buf[256];
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dbg_log (_("short write in %s: %s"), __FUNCTION__,
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strerror_r (errno, buf, sizeof (buf)));
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}
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return timeout;
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}
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void
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addinitgroups (struct database_dyn *db, int fd, request_header *req, void *key,
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uid_t uid)
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{
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addinitgroupsX (db, fd, req, key, uid, NULL, NULL);
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}
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time_t
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readdinitgroups (struct database_dyn *db, struct hashentry *he,
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struct datahead *dh)
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{
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request_header req =
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{
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.type = INITGROUPS,
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.key_len = he->len
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};
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return addinitgroupsX (db, -1, &req, db->data + he->key, he->owner, he, dh);
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}
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