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g10: Fix a race condition initially creating trustdb.

* g10/tdbio.c (take_write_lock, release_write_lock): New.
(put_record_into_cache, tdbio_sync, tdbio_end_transaction): Use
new lock functions.
(tdbio_set_dbname): Fix the race.
(open_db): Don't call dotlock_create.

--

(backported from 2.1 commit fe5c6edaed)
GnuPG-bug-id: 1675
This commit is contained in:
NIIBE Yutaka 2015-06-15 14:38:05 +09:00
parent f3b00d88ef
commit 6f992d94ea

View File

@ -94,7 +94,33 @@ static int in_transaction;
static void open_db(void);
static void migrate_from_v2 (void);
static int
take_write_lock (void)
{
if (!lockhandle)
lockhandle = dotlock_create (db_name, 0);
if (!lockhandle)
log_fatal ( _("can't create lock for '%s'\n"), db_name );
if (!is_locked)
{
if (dotlock_take (lockhandle, -1) )
log_fatal ( _("can't lock '%s'\n"), db_name );
else
is_locked = 1;
return 0;
}
else
return 1;
}
static void
release_write_lock (void)
{
if (!opt.lock_once)
if (!dotlock_release (lockhandle))
is_locked = 0;
}
/*************************************
************* record cache **********
@ -247,12 +273,7 @@ put_record_into_cache( ulong recno, const char *data )
int n = dirty_count / 5; /* discard some dirty entries */
if( !n )
n = 1;
if( !is_locked ) {
if (dotlock_take (lockhandle, -1))
log_fatal("can't acquire lock - giving up\n");
else
is_locked = 1;
}
take_write_lock ();
for( unused = NULL, r = cache_list; r; r = r->next ) {
if( r->flags.used && r->flags.dirty ) {
int rc = write_cache_item( r );
@ -266,10 +287,7 @@ put_record_into_cache( ulong recno, const char *data )
break;
}
}
if( !opt.lock_once ) {
if (!dotlock_release (lockhandle))
is_locked = 0;
}
release_write_lock ();
assert( unused );
r = unused;
r->flags.used = 1;
@ -308,13 +326,9 @@ tdbio_sync()
if( !cache_is_dirty )
return 0;
if( !is_locked ) {
if (dotlock_take (lockhandle, -1))
log_fatal("can't acquire lock - giving up\n");
else
is_locked = 1;
did_lock = 1;
}
if (!take_write_lock ())
did_lock = 1;
for( r = cache_list; r; r = r->next ) {
if( r->flags.used && r->flags.dirty ) {
int rc = write_cache_item( r );
@ -323,10 +337,8 @@ tdbio_sync()
}
}
cache_is_dirty = 0;
if( did_lock && !opt.lock_once ) {
if (!dotlock_release (lockhandle))
is_locked = 0;
}
if (did_lock)
release_write_lock ();
return 0;
}
@ -363,20 +375,12 @@ tdbio_end_transaction()
if( !in_transaction )
log_bug("tdbio: no active transaction\n");
if( !is_locked ) {
if (dotlock_take (lockhandle, -1))
log_fatal("can't acquire lock - giving up\n");
else
is_locked = 1;
}
take_write_lock ();
block_all_signals();
in_transaction = 0;
rc = tdbio_sync();
unblock_all_signals();
if( !opt.lock_once ) {
if (!dotlock_release (lockhandle))
is_locked = 0;
}
release_write_lock ();
return rc;
}
@ -474,6 +478,7 @@ int
tdbio_set_dbname( const char *new_dbname, int create, int *r_nofile)
{
char *fname;
struct stat statbuf;
static int initialized = 0;
if( !initialized ) {
@ -495,12 +500,25 @@ tdbio_set_dbname( const char *new_dbname, int create, int *r_nofile)
else
fname = xstrdup (new_dbname);
xfree (db_name);
db_name = fname;
/*
* Quick check for (likely) case where there is trustdb.gpg
* already. This check is not required in theory, but it helps in
* practice, avoiding costly operations of preparing and taking
* the lock.
*/
if (stat (fname, &statbuf) == 0 && statbuf.st_size > 0)
/* OK, we have the valid trustdb.gpg already. */
return 0;
take_write_lock ();
if( access( fname, R_OK ) ) {
if( errno != ENOENT ) {
log_error( _("can't access `%s': %s\n"), fname, strerror(errno) );
xfree(fname);
return G10ERR_TRUSTDB;
}
if( errno != ENOENT )
log_fatal( _("can't access '%s': %s\n"), fname, strerror(errno) );
if (!create)
*r_nofile = 1;
else {
@ -519,16 +537,6 @@ tdbio_set_dbname( const char *new_dbname, int create, int *r_nofile)
}
*p = DIRSEP_C;
xfree(db_name);
db_name = fname;
#ifdef __riscos__
if( !lockhandle )
lockhandle = dotlock_create (db_name, 0);
if( !lockhandle )
log_fatal( _("can't create lock for `%s'\n"), db_name );
if (dotlock_take (lockhandle, -1))
log_fatal( _("can't lock `%s'\n"), db_name );
#endif /* __riscos__ */
oldmask=umask(077);
if (is_secured_filename (fname)) {
fp = NULL;
@ -544,13 +552,6 @@ tdbio_set_dbname( const char *new_dbname, int create, int *r_nofile)
if( db_fd == -1 )
log_fatal( _("can't open `%s': %s\n"), db_name, strerror(errno) );
#ifndef __riscos__
if( !lockhandle )
lockhandle = dotlock_create (db_name, 0);
if( !lockhandle )
log_fatal( _("can't create lock for `%s'\n"), db_name );
#endif /* !__riscos__ */
rc = create_version_record ();
if( rc )
log_fatal( _("%s: failed to create version record: %s"),
@ -561,12 +562,10 @@ tdbio_set_dbname( const char *new_dbname, int create, int *r_nofile)
if( !opt.quiet )
log_info(_("%s: trustdb created\n"), db_name);
return 0;
}
}
xfree(db_name);
db_name = fname;
release_write_lock ();
return 0;
}
@ -588,14 +587,6 @@ open_db()
assert( db_fd == -1 );
if (!lockhandle )
lockhandle = dotlock_create (db_name, 0);
if (!lockhandle )
log_fatal( _("can't create lock for `%s'\n"), db_name );
#ifdef __riscos__
if (dotlock_take (lockhandle, -1))
log_fatal( _("can't lock `%s'\n"), db_name );
#endif /* __riscos__ */
db_fd = open (db_name, O_RDWR | MY_O_BINARY );
if (db_fd == -1 && (errno == EACCES
#ifdef EROFS