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gpg: Keep a lock during the read-update/insert cycle in import. 

* g10/keydb.c (keydb_handle): New field 'keep_lock'.
(keydb_release): Clear that flag.
(keydb_lock): New function.
(unlock_all): Skip if KEEP_LOCK is set.
* g10/getkey.c (get_keyblock_byfprint_fast): Call keep_lock if
requested.
--

That change is straightforward.  It helps to avoid the race condition
that another gpg process inserts a key while the first process is
between the search and the insert.

A similar change is due for gpgsm.

Note that the key edit operations may still suffer from a race.

GnuPG-bug-id: 3446
This commit is contained in:
Werner Koch 2017-10-18 18:28:52 +02:00
parent 8448347b5b
commit 7c73db3d31
No known key found for this signature in database
GPG Key ID: E3FDFF218E45B72B
3 changed files with 41 additions and 3 deletions
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15
g10/getkey.c
View File

@ -1877,14 +1877,25 @@ get_keyblock_byfprint_fast (kbnode_t *r_keyblock, KEYDB_HANDLE *r_hd,
hd = keydb_new ();
if (!hd)
return gpg_error_from_syserror ();
if (r_hd)
*r_hd = hd;
if (lock)
{
err = keydb_lock (hd);
if (err)
{
/* If locking did not work, we better don't return a handle
* at all - there was a reason that locking has been
* requested. */
keydb_release (hd);
return err;
}
keydb_disable_caching (hd);
}
/* Fo all other errors we return the handle. */
if (r_hd)
*r_hd = hd;
err = keydb_search_fpr (hd, fprbuf);
if (gpg_err_code (err) == GPG_ERR_NOT_FOUND)
{

25
g10/keydb.c
View File

@ -96,6 +96,10 @@ struct keydb_handle
/ keybox_lock, as appropriate). */
int locked;
/* If this flag is set a lock will only be released by
* keydb_release. */
int keep_lock;
/* The index into ACTIVE of the resources in which the last search
result was found. Initially -1. */
int found;
@ -964,6 +968,7 @@ keydb_release (KEYDB_HANDLE hd)
log_assert (active_handles > 0);
active_handles--;
hd->keep_lock = 0;
unlock_all (hd);
for (i=0; i < hd->used; i++)
{
@ -985,6 +990,24 @@ keydb_release (KEYDB_HANDLE hd)
}
/* Take a lock on the files immediately and not only during insert or
* update. This lock is released with keydb_release. */
gpg_error_t
keydb_lock (KEYDB_HANDLE hd)
{
gpg_error_t err;
if (!hd)
return gpg_error (GPG_ERR_INV_ARG);
err = lock_all (hd);
if (!err)
hd->keep_lock = 1;
return err;
}
/* Set a flag on the handle to suppress use of cached results. This
* is required for updating a keyring and for key listings. Fixme:
* Using a new parameter for keydb_new might be a better solution. */
@ -1098,7 +1121,7 @@ unlock_all (KEYDB_HANDLE hd)
{
int i;
if (!hd->locked)
if (!hd->locked || hd->keep_lock)
return;
for (i=hd->used-1; i >= 0; i--)

4
g10/keydb.h
View File

@ -154,6 +154,10 @@ KEYDB_HANDLE keydb_new (void);
/* Free all resources owned by the database handle. */
void keydb_release (KEYDB_HANDLE hd);
/* Take a lock on the files immediately and not only during insert or
* update. This lock is released with keydb_release. */
gpg_error_t keydb_lock (KEYDB_HANDLE hd);
/* Set a flag on the handle to suppress use of cached results. This
is required for updating a keyring and for key listings. Fixme:
Using a new parameter for keydb_new might be a better solution. */