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agent: Fix detection of exit of scdaemon. 

* agent/call-scd.c (start_scd): Acquire START_SCD_LOCK for
SCD_LOCAL_LIST.  Move common case code to fast path.
Release START_SCD_LOCK before calling unlock_scd.
When new CTX is allocated, clear INVALID flag.
(agent_reset_scd): Serialize the access to SCD_LOCAL_LIST by
START_SCD_LOCK.

--

GnuPG-bug-id: 4377
Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
This commit is contained in:
NIIBE Yutaka 2019-03-06 10:33:54 +09:00
parent 8d4af54ddd
commit 2abad7585a
1 changed files with 80 additions and 62 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

142
agent/call-scd.c
View File

@ -303,33 +303,19 @@ start_scd (ctrl_t ctrl)
if (opt.disable_scdaemon)
return gpg_error (GPG_ERR_NOT_SUPPORTED);
/* If this is the first call for this session, setup the local data
structure. */
if (!ctrl->scd_local)
if (ctrl->scd_local && ctrl->scd_local->ctx)
{
ctrl->scd_local = xtrycalloc (1, sizeof *ctrl->scd_local);
if (!ctrl->scd_local)
return gpg_error_from_syserror ();
ctrl->scd_local->next_local = scd_local_list;
scd_local_list = ctrl->scd_local;
ctrl->scd_local->in_use = 1;
return 0; /* Okay, the context is fine. */
}
if (ctrl->scd_local->in_use)
if (ctrl->scd_local && ctrl->scd_local->in_use)
{
log_error ("start_scd: CTX is in use\n");
return gpg_error (GPG_ERR_INTERNAL);
}
ctrl->scd_local->in_use = 1;
if (ctrl->scd_local->ctx)
return 0; /* Okay, the context is fine. We used to test for an
alive context here and do an disconnect. Now that we
have a ticker function to check for it, it is easier
not to check here but to let the connection run on an
error instead. */
/* We need to protect the following code. */
/* We need to serialize the access to scd_local_list and primary_scd_ctx. */
rc = npth_mutex_lock (&start_scd_lock);
if (rc)
{
@ -338,6 +324,25 @@ start_scd (ctrl_t ctrl)
return gpg_error (GPG_ERR_INTERNAL);
}
/* If this is the first call for this session, setup the local data
structure. */
if (!ctrl->scd_local)
{
ctrl->scd_local = xtrycalloc (1, sizeof *ctrl->scd_local);
if (!ctrl->scd_local)
{
err = gpg_error_from_syserror ();
rc = npth_mutex_unlock (&start_scd_lock);
if (rc)
log_error ("failed to release the start_scd lock: %s\n", strerror (rc));
return err;
}
ctrl->scd_local->next_local = scd_local_list;
scd_local_list = ctrl->scd_local;
}
ctrl->scd_local->in_use = 1;
/* Check whether the pipe server has already been started and in
this case either reuse a lingering pipe connection or establish a
new socket based one. */
@ -522,6 +527,10 @@ start_scd (ctrl_t ctrl)
}
leave:
rc = npth_mutex_unlock (&start_scd_lock);
if (rc)
log_error ("failed to release the start_scd lock: %s\n", strerror (rc));
xfree (abs_homedir);
if (err)
{
@ -531,11 +540,9 @@ start_scd (ctrl_t ctrl)
}
else
{
ctrl->scd_local->invalid = 0;
ctrl->scd_local->ctx = ctx;
}
rc = npth_mutex_unlock (&start_scd_lock);
if (rc)
log_error ("failed to release the start_scd lock: %s\n", strerror (rc));
return err;
}
@ -555,53 +562,64 @@ agent_scd_check_running (void)
int
agent_reset_scd (ctrl_t ctrl)
{
if (ctrl->scd_local)
int err = npth_mutex_lock (&start_scd_lock);
if (err)
{
if (ctrl->scd_local->ctx)
log_error ("failed to acquire the start_scd lock: %s\n",
strerror (err));
}
else
{
if (ctrl->scd_local)
{
/* We can't disconnect the primary context because libassuan
does a waitpid on it and thus the system would hang.
Instead we send a reset and keep that connection for
reuse. */
if (ctrl->scd_local->ctx == primary_scd_ctx)
if (ctrl->scd_local->ctx)
{
/* Send a RESTART to the SCD. This is required for the
primary connection as a kind of virtual EOF; we don't
have another way to tell it that the next command
should be viewed as if a new connection has been
made. For the non-primary connections this is not
needed as we simply close the socket. We don't check
for an error here because the RESTART may fail for
example if the scdaemon has already been terminated.
Anyway, we need to set the reusable flag to make sure
that the aliveness check can clean it up. */
assuan_transact (primary_scd_ctx, "RESTART",
NULL, NULL, NULL, NULL, NULL, NULL);
primary_scd_ctx_reusable = 1;
/* We send a reset and keep that connection for reuse. */
if (ctrl->scd_local->ctx == primary_scd_ctx)
{
/* Send a RESTART to the SCD. This is required for the
primary connection as a kind of virtual EOF; we don't
have another way to tell it that the next command
should be viewed as if a new connection has been
made. For the non-primary connections this is not
needed as we simply close the socket. We don't check
for an error here because the RESTART may fail for
example if the scdaemon has already been terminated.
Anyway, we need to set the reusable flag to make sure
that the aliveness check can clean it up. */
assuan_transact (primary_scd_ctx, "RESTART",
NULL, NULL, NULL, NULL, NULL, NULL);
primary_scd_ctx_reusable = 1;
}
else
assuan_release (ctrl->scd_local->ctx);
ctrl->scd_local->ctx = NULL;
}
else
assuan_release (ctrl->scd_local->ctx);
ctrl->scd_local->ctx = NULL;
}
/* Remove the local context from our list and release it. */
if (!scd_local_list)
BUG ();
else if (scd_local_list == ctrl->scd_local)
scd_local_list = ctrl->scd_local->next_local;
else
{
struct scd_local_s *sl;
for (sl=scd_local_list; sl->next_local; sl = sl->next_local)
if (sl->next_local == ctrl->scd_local)
break;
if (!sl->next_local)
/* Remove the local context from our list and release it. */
if (!scd_local_list)
BUG ();
sl->next_local = ctrl->scd_local->next_local;
else if (scd_local_list == ctrl->scd_local)
scd_local_list = ctrl->scd_local->next_local;
else
{
struct scd_local_s *sl;
for (sl=scd_local_list; sl->next_local; sl = sl->next_local)
if (sl->next_local == ctrl->scd_local)
break;
if (!sl->next_local)
BUG ();
sl->next_local = ctrl->scd_local->next_local;
}
xfree (ctrl->scd_local);
ctrl->scd_local = NULL;
}
xfree (ctrl->scd_local);
ctrl->scd_local = NULL;
err = npth_mutex_unlock (&start_scd_lock);
if (err)
log_error ("failed to release the start_scd lock: %s\n", strerror (err));
}
return 0;