oysteikt/heimdal
0
0
Fork 0
Code Issues 5 Pull Requests Releases Activity

Fix locking issues in DB3 HDB backend.

Browse Source 
Multiple concurrent writers would cause the HDB to become corrupted
as the locking was not sufficient to prevent these sorts of issues
from occurring.  We fix this in a similar way to the prior DB1 patch.
This commit is contained in:
Roland C. Dowdeswell
2012-05-18 13:03:23 +01:00
parent 1f63d6e4dc
commit fde1d8cb72
1 changed files with 76 additions and 58 deletions
Download Patch File Download Diff File Expand all files Collapse all files

134
lib/hdb/db3.c
View File

@@ -33,6 +33,8 @@
#include "hdb_locl.h"
#include <fcntl.h>
#if HAVE_DB3
#ifdef HAVE_DBHEADER
@@ -47,15 +49,32 @@
#include <db.h>
#endif
typedef struct {
HDB hdb; /* generic members */
int lock_fd; /* DB3-specific */
} DB3_HDB;
static krb5_error_code
DB_close(krb5_context context, HDB *db)
{
DB3_HDB *db3 = (DB3_HDB *)db;
DB *d = (DB*)db->hdb_db;
DBC *dbcp = (DBC*)db->hdb_dbc;
DBC *dbcp;
heim_assert(d != 0, "Closing already closed HDB");
dbcp = (DBC*)db->hdb_dbc;
(*dbcp->c_close)(dbcp);
db->hdb_dbc = 0;
(*d->close)(d, 0);
db->hdb_db = 0;
if (db3->lock_fd >= 0) {
close(db3->lock_fd);
db3->lock_fd = -1;
}
return 0;
}
@@ -73,41 +92,15 @@ DB_destroy(krb5_context context, HDB *db)
static krb5_error_code
DB_lock(krb5_context context, HDB *db, int operation)
{
DB *d = (DB*)db->hdb_db;
int fd;
krb5_error_code ret;
if (db->lock_count > 1) {
db->lock_count++;
if (db->lock_count == HDB_WLOCK || db->lock_count == operation)
return 0;
}
if ((*d->fd)(d, &fd))
return HDB_ERR_CANT_LOCK_DB;
ret = hdb_lock(fd, operation);
if (ret)
return ret;
db->lock_count++;
return 0;
}
static krb5_error_code
DB_unlock(krb5_context context, HDB *db)
{
DB *d = (DB*)db->hdb_db;
int fd;
if (db->lock_count > 1) {
db->lock_count--;
return 0;
}
heim_assert(db->lock_count == 1, "HDB lock/unlock sequence does not match");
db->lock_count--;
if ((*d->fd)(d, &fd))
return HDB_ERR_CANT_LOCK_DB;
return hdb_unlock(fd);
return 0;
}
@@ -122,10 +115,7 @@ DB_seq(krb5_context context, HDB *db,
memset(&key, 0, sizeof(DBT));
memset(&value, 0, sizeof(DBT));
if ((*db->hdb_lock)(context, db, HDB_RLOCK))
return HDB_ERR_DB_INUSE;
code = (*dbcp->c_get)(dbcp, &key, &value, flag);
(*db->hdb_unlock)(context, db); /* XXX check value */
if (code == DB_NOTFOUND)
return HDB_ERR_NOENTRY;
if (code)
@@ -209,10 +199,7 @@ DB__get(krb5_context context, HDB *db, krb5_data key, krb5_data *reply)
k.data = key.data;
k.size = key.length;
k.flags = 0;
if ((code = (*db->hdb_lock)(context, db, HDB_RLOCK)))
return code;
code = (*d->get)(d, NULL, &k, &v, 0);
(*db->hdb_unlock)(context, db);
if(code == DB_NOTFOUND)
return HDB_ERR_NOENTRY;
if(code)
@@ -238,10 +225,7 @@ DB__put(krb5_context context, HDB *db, int replace,
v.data = value.data;
v.size = value.length;
v.flags = 0;
if ((code = (*db->hdb_lock)(context, db, HDB_WLOCK)))
return code;
code = (*d->put)(d, NULL, &k, &v, replace ? 0 : DB_NOOVERWRITE);
(*db->hdb_unlock)(context, db);
if(code == DB_KEYEXIST)
return HDB_ERR_EXISTS;
if(code)
@@ -259,11 +243,7 @@ DB__del(krb5_context context, HDB *db, krb5_data key)
k.data = key.data;
k.size = key.length;
k.flags = 0;
code = (*db->hdb_lock)(context, db, HDB_WLOCK);
if(code)
return code;
code = (*d->del)(d, NULL, &k, 0);
(*db->hdb_unlock)(context, db);
if(code == DB_NOTFOUND)
return HDB_ERR_NOENTRY;
if(code)
@@ -271,9 +251,52 @@ DB__del(krb5_context context, HDB *db, krb5_data key)
return 0;
}
#define RD_CACHE_SZ 0x8000 /* Minimal read cache size */
#define WR_CACHE_SZ 0x8000 /* Minimal write cache size */
static int
_open_db(DB *d, char *fn, int myflags, int flags, mode_t mode, int *fd)
{
int ret;
int cache_size = (myflags & DB_RDONLY) ? RD_CACHE_SZ : WR_CACHE_SZ;
*fd = open(fn, flags, mode);
if (*fd == -1)
return errno;
/*
* Without DB_FCNTL_LOCKING, the DB library complains when initializing
* a database in an empty file. Since the database is our lock file,
* we create it before Berkeley DB does, so a new DB always starts empty.
*/
myflags |= DB_FCNTL_LOCKING;
ret = flock(*fd, (myflags&DB_RDONLY) ? LOCK_SH : LOCK_EX);
if (ret == -1) {
ret = errno;
close(*fd);
return ret;
}
d->set_cachesize(d, 0, cache_size, 0);
#if (DB_VERSION_MAJOR >= 4) && (DB_VERSION_MINOR >= 1)
ret = (*d->open)(d, NULL, fn, NULL, DB_BTREE, myflags, mode);
#else
ret = (*d->open)(d, fn, NULL, DB_BTREE, myflags, mode);
#endif
if (ret != 0)
close(*fd);
return ret;
}
static krb5_error_code
DB_open(krb5_context context, HDB *db, int flags, mode_t mode)
{
DB3_HDB *db3 = (DB3_HDB *)db;
DBC *dbc = NULL;
char *fn;
krb5_error_code ret;
@@ -281,6 +304,8 @@ DB_open(krb5_context context, HDB *db, int flags, mode_t mode)
int myflags = 0;
int aret;
heim_assert(db->hdb_db == 0, "Opening already open HDB");
if (flags & O_CREAT)
myflags |= DB_CREATE;
@@ -298,6 +323,7 @@ DB_open(krb5_context context, HDB *db, int flags, mode_t mode)
krb5_set_error_message(context, ENOMEM, "malloc: out of memory");
return ENOMEM;
}
if (db_create(&d, NULL, 0) != 0) {
free(fn);
krb5_set_error_message(context, ENOMEM, "malloc: out of memory");
@@ -305,30 +331,19 @@ DB_open(krb5_context context, HDB *db, int flags, mode_t mode)
}
db->hdb_db = d;
#if (DB_VERSION_MAJOR >= 4) && (DB_VERSION_MINOR >= 1)
ret = (*d->open)(db->hdb_db, NULL, fn, NULL, DB_BTREE, myflags, mode);
#else
ret = (*d->open)(db->hdb_db, fn, NULL, DB_BTREE, myflags, mode);
#endif
ret = _open_db(d, fn, myflags, flags, mode, &db3->lock_fd);
free(fn);
if (ret == ENOENT) {
/* try to open without .db extension */
#if (DB_VERSION_MAJOR >= 4) && (DB_VERSION_MINOR >= 1)
ret = (*d->open)(db->hdb_db, NULL, db->hdb_name, NULL, DB_BTREE,
myflags, mode);
#else
ret = (*d->open)(db->hdb_db, db->hdb_name, NULL, DB_BTREE,
myflags, mode);
#endif
ret = _open_db(d, db->hdb_name, myflags, flags,
mode, &db3->lock_fd);
}
if (ret) {
free(fn);
krb5_set_error_message(context, ret, "opening %s: %s",
db->hdb_name, strerror(ret));
db->hdb_name, strerror(ret));
return ret;
}
free(fn);
ret = (*d->cursor)(d, NULL, &dbc, 0);
if (ret) {
@@ -358,7 +373,8 @@ krb5_error_code
hdb_db_create(krb5_context context, HDB **db,
const char *filename)
{
*db = calloc(1, sizeof(**db));
DB3_HDB **db3 = (DB3_HDB **)db;
*db = calloc(1, sizeof(**db3)); /* Allocate space for the larger db3 */
if (*db == NULL) {
krb5_set_error_message(context, ENOMEM, "malloc: out of memory");
return ENOMEM;
@@ -389,6 +405,8 @@ hdb_db_create(krb5_context context, HDB **db,
(*db)->hdb__put = DB__put;
(*db)->hdb__del = DB__del;
(*db)->hdb_destroy = DB_destroy;
(*db3)->lock_fd = -1;
return 0;
}
#endif /* HAVE_DB3 */