diff options
Diffstat (limited to 'nscd/initgrcache.c')
| -rw-r--r-- | nscd/initgrcache.c | 391 |
1 files changed, 391 insertions, 0 deletions
diff --git a/nscd/initgrcache.c b/nscd/initgrcache.c new file mode 100644 index 0000000000..124b4bae62 --- /dev/null +++ b/nscd/initgrcache.c @@ -0,0 +1,391 @@ +/* Cache handling for host lookup. + Copyright (C) 2004 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@redhat.com>, 2004. + + 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 <grp.h> +#include <libintl.h> +#include <string.h> +#include <time.h> +#include <unistd.h> +#include <sys/mman.h> +#include <dbg_log.h> +#include <nscd.h> + +#include "../nss/nsswitch.h" + + +/* Type of the lookup function. */ +typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t, + long int *, long int *, + gid_t **, long int, int *); + + +static const initgr_response_header notfound = +{ + .version = NSCD_VERSION, + .found = 0, + .ngrps = 0 +}; + + +#include "../grp/compat-initgroups.c" + + +static void +addinitgroupsX (struct database_dyn *db, int fd, request_header *req, + void *key, uid_t uid, struct hashentry *he, + struct datahead *dh) +{ + /* Search for the entry matching the key. Please note that we don't + look again in the table whether the dataset is now available. We + simply insert it. It does not matter if it is in there twice. The + pruning function only will look at the timestamp. */ + + + /* We allocate all data in one memory block: the iov vector, + the response header and the dataset itself. */ + struct dataset + { + struct datahead head; + initgr_response_header resp; + char strdata[0]; + } *dataset = NULL; + + if (__builtin_expect (debug_level > 0, 0)) + { + if (he == NULL) + dbg_log (_("Haven't found \"%s\" in group cache!"), (char *) key); + else + dbg_log (_("Reloading \"%s\" in group cache!"), (char *) key); + } + + static service_user *group_database; + service_user *nip = NULL; + int no_more; + + if (group_database != NULL) + { + nip = group_database; + no_more = 0; + } + else + no_more = __nss_database_lookup ("group", NULL, + "compat [NOTFOUND=return] files", &nip); + + /* We always use sysconf even if NGROUPS_MAX is defined. That way, the + limit can be raised in the kernel configuration without having to + recompile libc. */ + long int limit = __sysconf (_SC_NGROUPS_MAX); + + long int size; + if (limit > 0) + /* We limit the size of the intially allocated array. */ + size = MIN (limit, 64); + else + /* No fixed limit on groups. Pick a starting buffer size. */ + size = 16; + + long int start = 0; + bool all_tryagain = true; + + /* This is temporary memory, we need not (ad must not) call + mempool_alloc. */ + // XXX This really should use alloca. need to change the backends. + gid_t *groups = (gid_t *) malloc (size * sizeof (gid_t)); + if (__builtin_expect (groups == NULL, 0)) + /* No more memory. */ + goto out; + + /* Nothing added yet. */ + while (! no_more) + { + enum nss_status status; + initgroups_dyn_function fct; + fct = __nss_lookup_function (nip, "initgroups_dyn"); + + if (fct == NULL) + { + status = compat_call (nip, key, -1, &start, &size, &groups, + limit, &errno); + + if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE) + break; + } + else + status = DL_CALL_FCT (fct, (key, -1, &start, &size, &groups, + limit, &errno)); + + if (status != NSS_STATUS_TRYAGAIN) + all_tryagain = false; + + /* This is really only for debugging. */ + if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN) + __libc_fatal ("illegal status in internal_getgrouplist"); + + if (status != NSS_STATUS_SUCCESS + && nss_next_action (nip, status) == NSS_ACTION_RETURN) + break; + + if (nip->next == NULL) + no_more = -1; + else + nip = nip->next; + } + + ssize_t total; + ssize_t written; + out: + if (start == 0) + { + /* Nothing found. Create a negative result record. */ + written = total = sizeof (notfound); + + if (he != NULL && all_tryagain) + { + /* If we have an old record available but cannot find one now + because the service is not available we keep the old record + and make sure it does not get removed. */ + if (reload_count != UINT_MAX && dh->nreloads == reload_count) + /* Do not reset the value if we never not reload the record. */ + dh->nreloads = reload_count - 1; + } + else + { + /* We have no data. This means we send the standard reply for this + case. */ + if (fd != -1) + written = TEMP_FAILURE_RETRY (write (fd, ¬found, total)); + + dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len); + /* If we cannot permanently store the result, so be it. */ + if (dataset != NULL) + { + dataset->head.allocsize = sizeof (struct dataset) + req->key_len; + dataset->head.recsize = total; + dataset->head.notfound = true; + dataset->head.nreloads = 0; + dataset->head.usable = true; + + /* Compute the timeout time. */ + dataset->head.timeout = time (NULL) + db->negtimeout; + + /* This is the reply. */ + memcpy (&dataset->resp, ¬found, total); + + /* Copy the key data. */ + char *key_copy = memcpy (dataset->strdata, key, req->key_len); + + /* If necessary, we also propagate the data to disk. */ + if (db->persistent) + { + // XXX async OK? + uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; + msync ((void *) pval, + ((uintptr_t) dataset & pagesize_m1) + + sizeof (struct dataset) + req->key_len, MS_ASYNC); + } + + /* Now get the lock to safely insert the records. */ + pthread_rwlock_rdlock (&db->lock); + + if (cache_add (req->type, key_copy, req->key_len, + &dataset->head, true, db, uid) < 0) + /* Ensure the data can be recovered. */ + dataset->head.usable = false; + + pthread_rwlock_unlock (&db->lock); + + /* Mark the old entry as obsolete. */ + if (dh != NULL) + dh->usable = false; + } + else + ++db->head->addfailed; + } + } + else + { + + written = total = sizeof (struct dataset) + start * sizeof (int32_t); + + /* If we refill the cache, first assume the reconrd did not + change. Allocate memory on the cache since it is likely + discarded anyway. If it turns out to be necessary to have a + new record we can still allocate real memory. */ + bool alloca_used = false; + dataset = NULL; + + if (he == NULL) + { + dataset = (struct dataset *) mempool_alloc (db, + total + req->key_len); + if (dataset == NULL) + ++db->head->addfailed; + } + + if (dataset == NULL) + { + /* We cannot permanently add the result in the moment. But + we can provide the result as is. Store the data in some + temporary memory. */ + dataset = (struct dataset *) alloca (total + req->key_len); + + /* We cannot add this record to the permanent database. */ + alloca_used = true; + } + + dataset->head.allocsize = total + req->key_len; + dataset->head.recsize = total - offsetof (struct dataset, resp); + dataset->head.notfound = false; + dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1); + dataset->head.usable = true; + + /* Compute the timeout time. */ + dataset->head.timeout = time (NULL) + db->postimeout; + + dataset->resp.version = NSCD_VERSION; + dataset->resp.found = 1; + dataset->resp.ngrps = start; + + char *cp = dataset->strdata; + + /* Copy the GID values. If the size of the types match this is + very simple. */ + if (sizeof (gid_t) == sizeof (int32_t)) + cp = mempcpy (cp, groups, start * sizeof (gid_t)); + else + { + gid_t *gcp = (gid_t *) cp; + + for (int i = 0; i < start; ++i) + *gcp++ = groups[i]; + + cp = (char *) gcp; + } + + /* Finally the user name. */ + memcpy (cp, key, req->key_len); + + /* Now we can determine whether on refill we have to create a new + record or not. */ + if (he != NULL) + { + assert (fd == -1); + + if (total + req->key_len == dh->allocsize + && total - offsetof (struct dataset, resp) == dh->recsize + && memcmp (&dataset->resp, dh->data, + dh->allocsize - offsetof (struct dataset, resp)) == 0) + { + /* The data has not changed. We will just bump the + timeout value. Note that the new record has been + allocated on the stack and need not be freed. */ + dh->timeout = dataset->head.timeout; + ++dh->nreloads; + } + else + { + /* We have to create a new record. Just allocate + appropriate memory and copy it. */ + struct dataset *newp + = (struct dataset *) mempool_alloc (db, total + req->key_len); + if (newp != NULL) + { + /* Adjust pointer into the memory block. */ + cp = (char *) newp + (cp - (char *) dataset); + + dataset = memcpy (newp, dataset, total + req->key_len); + alloca_used = false; + } + + /* Mark the old record as obsolete. */ + dh->usable = false; + } + } + else + { + /* We write the dataset before inserting it to the database + since while inserting this thread might block and so would + unnecessarily let the receiver wait. */ + assert (fd != -1); + + written = TEMP_FAILURE_RETRY (write (fd, &dataset->resp, total)); + } + + + /* Add the record to the database. But only if it has not been + stored on the stack. */ + if (! alloca_used) + { + /* If necessary, we also propagate the data to disk. */ + if (db->persistent) + { + // XXX async OK? + uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; + msync ((void *) pval, + ((uintptr_t) dataset & pagesize_m1) + total + + req->key_len, MS_ASYNC); + } + + /* Now get the lock to safely insert the records. */ + pthread_rwlock_rdlock (&db->lock); + + if (cache_add (INITGROUPS, cp, req->key_len, &dataset->head, true, + db, uid) < 0) + /* Could not allocate memory. Make sure the data gets + discarded. */ + dataset->head.usable = false; + + pthread_rwlock_unlock (&db->lock); + } + } + + free (groups); + + if (__builtin_expect (written != total, 0) && debug_level > 0) + { + char buf[256]; + dbg_log (_("short write in %s: %s"), __FUNCTION__, + strerror_r (errno, buf, sizeof (buf))); + } +} + + +void +addinitgroups (struct database_dyn *db, int fd, request_header *req, void *key, + uid_t uid) +{ + addinitgroupsX (db, fd, req, key, uid, NULL, NULL); +} + + +void +readdinitgroups (struct database_dyn *db, struct hashentry *he, + struct datahead *dh) +{ + request_header req = + { + .type = INITGROUPS, + .key_len = he->len + }; + + addinitgroupsX (db, -1, &req, db->data + he->key, he->owner, he, dh); +} |