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dirmngr: Fix signature checking.

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* dirmngr/server.c: Include cpparray.h.
(verify_swdb_parm_s): New.
(verify_swdb_status_cb): New.
(cmd_versioncheck): Use gpgv to correclty verify the signature.
Rename some variable to comply with GNU standards.
--

Relying on the return code of gpg is not a robust way to check
signatures.  We better use our dedicated tool.

Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch 2016-10-27 20:35:28 +02:00
parent 8fced66be3
commit 5a1f6a0062
No known key found for this signature in database
GPG Key ID: E3FDFF218E45B72B
1 changed files with 75 additions and 24 deletions
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99
dirmngr/server.c
View File

@ -54,6 +54,7 @@
#include "mbox-util.h"
#include "zb32.h"
#include "server-help.h"
#include "ccparray.h"
#include "../common/exectool.h"
/* To avoid DoS attacks we limit the size of a certificate to
@ -2546,6 +2547,29 @@ fetch_into_tmpdir (ctrl_t ctrl, const char *url, estream_t *strm_out,
}
struct verify_swdb_parm_s
{
time_t sigtime;
int anyvalid;
};
static void
verify_swdb_status_cb (void *opaque, const char *keyword, char *args)
{
struct verify_swdb_parm_s *parm = opaque;
/* We care only about the first valid signature. */
if (!strcmp (keyword, "VALIDSIG") && !parm->anyvalid)
{
char *fields[3];
parm->anyvalid = 1;
if (split_fields (args, fields, DIM (fields)) >= 3)
parm->sigtime = parse_timestamp (fields[2], NULL);
}
}
static const char hlp_versioncheck[] =
"VERSIONCHECK <name> <version>"
"\n"
@ -2570,13 +2594,17 @@ cmd_versioncheck (assuan_context_t ctx, char *line)
char* swdb_sig_dir = NULL;
char* buf = NULL;
size_t len = 0;
const char *argv[8];
char keyring_path[128];
char swdb_path[128];
char swdb_sig_path[128];
ccparray_t ccp;
const char **argv = NULL;
char keyring_name[128];
char swdb_name[128];
char swdb_sig_name[128];
swdb_path[0] = 0;
swdb_sig_path[0] = 0;
struct verify_swdb_parm_s verify_swdb_parm = { (time_t)(-1), 0 };
swdb_name[0] = 0;
swdb_sig_name[0] = 0;
ctrl = assuan_get_pointer (ctx);
if (split_fields (line, cmd_fields, 2) != 2)
@ -2594,29 +2622,51 @@ cmd_versioncheck (assuan_context_t ctx, char *line)
&swdb, &swdb_dir)))
goto out;
snprintf (swdb_path, sizeof swdb_path, "%s%s%s", swdb_dir, DIRSEP_S, "file");
snprintf (swdb_name, sizeof swdb_name, "%s%s%s", swdb_dir, DIRSEP_S, "file");
if ((err = fetch_into_tmpdir (ctrl, "https://versions.gnupg.org/swdb.lst.sig",
&swdb_sig, &swdb_sig_dir)))
goto out;
snprintf (keyring_path, sizeof keyring_path, "%s%s%s", gnupg_datadir (),
snprintf (keyring_name, sizeof keyring_name, "%s%s%s", gnupg_datadir (),
DIRSEP_S, "distsigkey.gpg");
snprintf (swdb_sig_path, sizeof swdb_sig_path, "%s%s%s", swdb_sig_dir,
snprintf (swdb_sig_name, sizeof swdb_sig_name, "%s%s%s", swdb_sig_dir,
DIRSEP_S, "file");
argv[0] = "--batch";
argv[1] = "--no-default-keyring";
argv[2] = "--keyring";
argv[3] = keyring_path;
argv[4] = "--verify";
argv[5] = swdb_sig_path;
argv[6] = "-";
argv[7] = NULL;
ccparray_init (&ccp, 0);
ccparray_put (&ccp, "--status-fd=2");
ccparray_put (&ccp, "--keyring");
ccparray_put (&ccp, keyring_name);
ccparray_put (&ccp, "--");
ccparray_put (&ccp, swdb_sig_name);
ccparray_put (&ccp, "-");
ccparray_put (&ccp, NULL);
argv = ccparray_get (&ccp, NULL);
if (!argv)
{
err = gpg_error_from_syserror ();
goto out;
}
if ((err = gnupg_exec_tool_stream (gnupg_module_name (GNUPG_MODULE_NAME_GPG),
argv, swdb, NULL, NULL, NULL, NULL)))
if ((err = gnupg_exec_tool_stream (gnupg_module_name (GNUPG_MODULE_NAME_GPGV),
argv, swdb, NULL, NULL,
verify_swdb_status_cb, &verify_swdb_parm)))
goto out;
if (verify_swdb_parm.sigtime == (time_t)(-1))
{
if (verify_swdb_parm.anyvalid)
err = gpg_error (GPG_ERR_BAD_SIGNATURE);
else
err = gpg_error (GPG_ERR_INV_TIME);
goto out;
}
{
gnupg_isotime_t tbuf;
epoch2isotime (tbuf, verify_swdb_parm.sigtime);
log_debug ("swdb created: %s\n", tbuf);
}
es_fseek (swdb, 0, SEEK_SET);
@ -2652,22 +2702,23 @@ cmd_versioncheck (assuan_context_t ctx, char *line)
err = assuan_send_data (ctx, "NOT_FOUND", strlen ("NOT_FOUND"));
out:
out:
es_fclose (swdb);
es_fclose (swdb_sig);
xfree (buf);
if (strlen (swdb_path) > 0)
unlink (swdb_path);
if (strlen (swdb_name) > 0)
remove (swdb_name);
if (swdb_dir)
rmdir (swdb_dir);
xfree (swdb_dir);
if (strlen (swdb_sig_path) > 0)
unlink (swdb_sig_path);
if (strlen (swdb_sig_name) > 0)
remove (swdb_sig_name);
if (swdb_sig_dir)
rmdir (swdb_sig_dir);
xfree (swdb_sig_dir);
xfree (argv);
return leave_cmd (ctx, err);
}