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agent: Fix deadlock in trustlist due to the switch to npth.

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* agent/trustlist.c (clear_trusttable): New.
(agent_reload_trustlist): Use new function.
(read_trustfiles): Require to be called with lock held.
(agent_istrusted): Factor all code out to ...
(istrusted_internal): new.  Add ALREADY_LOCKED arg.  Make sure the
table islocked.  Do not print TRUSTLISTFLAG stati if called internally.
(agent_marktrusted): Replace calls to agent_reload_trustlist by
explicit code.
--

In contrast to pth, npth does not use recursive mutexes by default.
However, the code in trustlist.c assumed recursive locks and thus we
had to rework it.
This commit is contained in:
Werner Koch 2012-04-30 14:37:36 +02:00
parent 8d7522837c
commit 0f02fba19d
1 changed files with 78 additions and 44 deletions
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122
agent/trustlist.c
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@ -1,5 +1,6 @@
/* trustlist.c - Maintain the list of trusted keys
* Copyright (C) 2002, 2004, 2006, 2007, 2009 Free Software Foundation, Inc.
* Copyright (C) 2002, 2004, 2006, 2007, 2009,
* 2012 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
@ -56,7 +57,6 @@ static size_t trusttablesize;
static npth_mutex_t trusttable_lock;
static const char headerblurb[] =
"# This is the list of trusted keys. Comment lines, like this one, as\n"
"# well as empty lines are ignored. Lines have a length limit but this\n"
@ -87,7 +87,7 @@ initialize_module_trustlist (void)
{
err = npth_mutex_init (&trusttable_lock, NULL);
if (err)
log_fatal ("error initializing mutex: %s\n", strerror (err));
log_fatal ("failed to init mutex in %s: %s\n", __FILE__,strerror (err));
initialized = 1;
}
}
@ -105,6 +105,7 @@ lock_trusttable (void)
log_fatal ("failed to acquire mutex in %s: %s\n", __FILE__, strerror (err));
}
static void
unlock_trusttable (void)
{
@ -116,6 +117,16 @@ unlock_trusttable (void)
}
/* Clear the trusttable. The caller needs to make sure that the
trusttable is locked. */
static inline void
clear_trusttable (void)
{
xfree (trusttable);
trusttable = NULL;
trusttablesize = 0;
}
static gpg_error_t
read_one_trustfile (const char *fname, int allow_include,
@ -315,7 +326,8 @@ read_one_trustfile (const char *fname, int allow_include,
}
/* Read the trust files and update the global table on success. */
/* Read the trust files and update the global table on success. The
trusttable is assumed to be locked. */
static gpg_error_t
read_trustfiles (void)
{
@ -356,11 +368,7 @@ read_trustfiles (void)
if (gpg_err_code (err) == GPG_ERR_ENOENT)
{
/* Take a missing trustlist as an empty one. */
lock_trusttable ();
xfree (trusttable);
trusttable = NULL;
trusttablesize = 0;
unlock_trusttable ();
clear_trusttable ();
err = 0;
}
return err;
@ -375,22 +383,23 @@ read_trustfiles (void)
return err;
}
lock_trusttable ();
/* Replace the trusttable. */
xfree (trusttable);
trusttable = ti;
trusttablesize = tableidx;
unlock_trusttable ();
return 0;
}
/* Check whether the given fpr is in our trustdb. We expect FPR to be
an all uppercase hexstring of 40 characters. */
gpg_error_t
agent_istrusted (ctrl_t ctrl, const char *fpr, int *r_disabled)
an all uppercase hexstring of 40 characters. If ALREADY_LOCKED is
true the function assumes that the trusttable is already locked. */
static gpg_error_t
istrusted_internal (ctrl_t ctrl, const char *fpr, int *r_disabled,
int already_locked)
{
gpg_error_t err;
int locked = already_locked;
trustitem_t *ti;
size_t len;
unsigned char fprbin[20];
@ -399,7 +408,16 @@ agent_istrusted (ctrl_t ctrl, const char *fpr, int *r_disabled)
*r_disabled = 0;
if ( hexcolon2bin (fpr, fprbin, 20) < 0 )
return gpg_error (GPG_ERR_INV_VALUE);
{
err = gpg_error (GPG_ERR_INV_VALUE);
goto leave;
}
if (!already_locked)
{
lock_trusttable ();
locked = 1;
}
if (!trusttable)
{
@ -407,7 +425,7 @@ agent_istrusted (ctrl_t ctrl, const char *fpr, int *r_disabled)
if (err)
{
log_error (_("error reading list of trusted root certificates\n"));
return err;
goto leave;
}
}
@ -419,26 +437,43 @@ agent_istrusted (ctrl_t ctrl, const char *fpr, int *r_disabled)
if (ti->flags.disabled && r_disabled)
*r_disabled = 1;
if (ti->flags.relax)
/* Print status messages only if we have not been called
in a locked state. */
if (already_locked)
;
else if (ti->flags.relax)
{
err = agent_write_status (ctrl,
"TRUSTLISTFLAG", "relax",
NULL);
if (err)
return err;
unlock_trusttable ();
locked = 0;
err = agent_write_status (ctrl, "TRUSTLISTFLAG", "relax", NULL);
}
else if (ti->flags.cm)
{
err = agent_write_status (ctrl,
"TRUSTLISTFLAG", "cm",
NULL);
if (err)
return err;
unlock_trusttable ();
locked = 0;
err = agent_write_status (ctrl, "TRUSTLISTFLAG", "cm", NULL);
}
return ti->flags.disabled? gpg_error (GPG_ERR_NOT_TRUSTED) : 0;
if (!err)
err = ti->flags.disabled? gpg_error (GPG_ERR_NOT_TRUSTED) : 0;
goto leave;
}
}
return gpg_error (GPG_ERR_NOT_TRUSTED);
err = gpg_error (GPG_ERR_NOT_TRUSTED);
leave:
if (locked && !already_locked)
unlock_trusttable ();
return err;
}
/* Check whether the given fpr is in our trustdb. We expect FPR to be
an all uppercase hexstring of 40 characters. */
gpg_error_t
agent_istrusted (ctrl_t ctrl, const char *fpr, int *r_disabled)
{
return istrusted_internal (ctrl, fpr, r_disabled, 0);
}
@ -451,11 +486,13 @@ agent_listtrusted (void *assuan_context)
gpg_error_t err;
size_t len;
lock_trusttable ();
if (!trusttable)
{
err = read_trustfiles ();
if (err)
{
unlock_trusttable ();
log_error (_("error reading list of trusted root certificates\n"));
return err;
}
@ -463,9 +500,6 @@ agent_listtrusted (void *assuan_context)
if (trusttable)
{
/* We need to lock the table because the scheduler may interrupt
assuan_send_data and an other thread may then re-read the table. */
lock_trusttable ();
for (ti=trusttable, len = trusttablesize; len; ti++, len--)
{
if (ti->flags.disabled)
@ -478,9 +512,9 @@ agent_listtrusted (void *assuan_context)
assuan_send_data (assuan_context, key, 43);
assuan_send_data (assuan_context, NULL, 0); /* flush */
}
unlock_trusttable ();
}
unlock_trusttable ();
return 0;
}
@ -553,10 +587,10 @@ reformat_name (const char *name, const char *replstring)
/* Insert the given fpr into our trustdb. We expect FPR to be an all
uppercase hexstring of 40 characters. FLAG is either 'P' or 'C'.
This function does first check whether that key has already been put
into the trustdb and returns success in this case. Before a FPR
actually gets inserted, the user is asked by means of the Pinentry
whether this is actual want he wants to do. */
This function does first check whether that key has already been
put into the trustdb and returns success in this case. Before a
FPR actually gets inserted, the user is asked by means of the
Pinentry whether this is actual what he wants to do. */
gpg_error_t
agent_marktrusted (ctrl_t ctrl, const char *name, const char *fpr, int flag)
{
@ -690,8 +724,8 @@ agent_marktrusted (ctrl_t ctrl, const char *name, const char *fpr, int flag)
/* Now check again to avoid duplicates. We take the lock to make
sure that nobody else plays with our file and force a reread. */
lock_trusttable ();
agent_reload_trustlist ();
if (!agent_istrusted (ctrl, fpr, &is_disabled) || is_disabled)
clear_trusttable ();
if (!istrusted_internal (ctrl, fpr, &is_disabled, 1) || is_disabled)
{
unlock_trusttable ();
xfree (fprformatted);
@ -747,11 +781,13 @@ agent_marktrusted (ctrl_t ctrl, const char *name, const char *fpr, int flag)
if (es_fclose (fp))
err = gpg_error_from_syserror ();
agent_reload_trustlist ();
clear_trusttable ();
xfree (fname);
unlock_trusttable ();
xfree (fprformatted);
xfree (nameformatted);
if (!err)
bump_key_eventcounter ();
return err;
}
@ -764,9 +800,7 @@ agent_reload_trustlist (void)
/* All we need to do is to delete the trusttable. At the next
access it will get re-read. */
lock_trusttable ();
xfree (trusttable);
trusttable = NULL;
trusttablesize = 0;
clear_trusttable ();
unlock_trusttable ();
bump_key_eventcounter ();
}