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gpg: Screen keyserver responses.

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* g10/main.h (import_filter_t): New.
* g10/import.c (import): Add filter callbacks to param list.
(import_one): Ditto.
(import_secret_one): Ditto.
(import_keys_internal): Ditto.
(import_keys_stream): Ditto.
* g10/keyserver.c (keyserver_retrieval_filter): New.
(keyserver_spawn): Pass filter to import_keys_stream()

--
These changes introduces import functions that apply a constraining
filter to imported keys. These filters can verify the fingerprints of
the keys returned before importing them into the keyring, ensuring that
the keys fetched from the keyserver are in fact those selected by the
user beforehand.

Signed-off-by: Stefan Tomanek <tomanek@internet-sicherheit.de>

Re-indention and minor changes by wk.

Resolved conflicts:
	g10/import.c
	g10/keyserver.c
	g10/main.h
This commit is contained in:
Stefan Tomanek 2014-01-30 00:57:43 +01:00 committed by Werner Koch
parent e790671cb3
commit 5e933008be
3 changed files with 164 additions and 80 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

70
g10/import.c
View File

@ -59,14 +59,17 @@ struct stats_s {
static int import( IOBUF inp, const char* fname,struct stats_s *stats,
unsigned char **fpr,size_t *fpr_len,unsigned int options );
unsigned char **fpr,size_t *fpr_len,unsigned int options,
import_filter_t filter, void *filter_arg );
static int read_block( IOBUF a, PACKET **pending_pkt, KBNODE *ret_root );
static void revocation_present(KBNODE keyblock);
static int import_one(const char *fname, KBNODE keyblock,struct stats_s *stats,
unsigned char **fpr,size_t *fpr_len,
unsigned int options,int from_sk);
unsigned int options,int from_sk,
import_filter_t filter, void *filter_arg);
static int import_secret_one( const char *fname, KBNODE keyblock,
struct stats_s *stats, unsigned int options);
struct stats_s *stats, unsigned int options,
import_filter_t filter, void *filter_arg);
static int import_revoke_cert( const char *fname, KBNODE node,
struct stats_s *stats);
static int chk_self_sigs( const char *fname, KBNODE keyblock,
@ -163,7 +166,8 @@ import_release_stats_handle (void *p)
static int
import_keys_internal( IOBUF inp, char **fnames, int nnames,
void *stats_handle, unsigned char **fpr, size_t *fpr_len,
unsigned int options )
unsigned int options,
import_filter_t filter, void *filter_arg)
{
int i, rc = 0;
struct stats_s *stats = stats_handle;
@ -172,7 +176,8 @@ import_keys_internal( IOBUF inp, char **fnames, int nnames,
stats = import_new_stats_handle ();
if (inp) {
rc = import( inp, "[stream]", stats, fpr, fpr_len, options);
rc = import (inp, "[stream]", stats, fpr, fpr_len, options,
filter, filter_arg);
}
else {
int once = (!fnames && !nnames);
@ -192,7 +197,8 @@ import_keys_internal( IOBUF inp, char **fnames, int nnames,
log_error(_("can't open `%s': %s\n"), fname, strerror(errno) );
else
{
rc = import( inp2, fname, stats, fpr, fpr_len, options );
rc = import (inp2, fname, stats, fpr, fpr_len, options,
NULL, NULL);
iobuf_close(inp2);
/* Must invalidate that ugly cache to actually close it. */
iobuf_ioctl (NULL, 2, 0, (char*)fname);
@ -223,24 +229,27 @@ void
import_keys( char **fnames, int nnames,
void *stats_handle, unsigned int options )
{
import_keys_internal(NULL,fnames,nnames,stats_handle,NULL,NULL,options);
import_keys_internal (NULL, fnames, nnames, stats_handle, NULL, NULL,
options, NULL, NULL);
}
int
import_keys_stream( IOBUF inp, void *stats_handle,
unsigned char **fpr, size_t *fpr_len,unsigned int options )
unsigned char **fpr, size_t *fpr_len,unsigned int options,
import_filter_t filter, void *filter_arg)
{
return import_keys_internal(inp,NULL,0,stats_handle,fpr,fpr_len,options);
return import_keys_internal (inp, NULL, 0, stats_handle, fpr, fpr_len,
options, filter, filter_arg);
}
static int
import( IOBUF inp, const char* fname,struct stats_s *stats,
unsigned char **fpr,size_t *fpr_len,unsigned int options )
import (IOBUF inp, const char* fname,struct stats_s *stats,
unsigned char **fpr, size_t *fpr_len, unsigned int options,
import_filter_t filter, void *filter_arg)
{
PACKET *pending_pkt = NULL;
KBNODE keyblock = NULL; /* Need to initialize because gcc can't
grasp the return semantics of
read_block. */
KBNODE keyblock = NULL;
int rc = 0;
getkey_disable_caches();
@ -256,9 +265,11 @@ import( IOBUF inp, const char* fname,struct stats_s *stats,
while( !(rc = read_block( inp, &pending_pkt, &keyblock) )) {
if( keyblock->pkt->pkttype == PKT_PUBLIC_KEY )
rc = import_one( fname, keyblock, stats, fpr, fpr_len, options, 0);
rc = import_one (fname, keyblock, stats, fpr, fpr_len, options, 0,
filter, filter_arg);
else if( keyblock->pkt->pkttype == PKT_SECRET_KEY )
rc = import_secret_one( fname, keyblock, stats, options );
rc = import_secret_one (fname, keyblock, stats, options,
filter, filter_arg);
else if( keyblock->pkt->pkttype == PKT_SIGNATURE
&& keyblock->pkt->pkt.signature->sig_class == 0x20 )
rc = import_revoke_cert( fname, keyblock, stats );
@ -745,7 +756,7 @@ check_prefs(KBNODE keyblock)
static int
import_one( const char *fname, KBNODE keyblock, struct stats_s *stats,
unsigned char **fpr,size_t *fpr_len,unsigned int options,
int from_sk )
int from_sk, import_filter_t filter, void *filter_arg)
{
PKT_public_key *pk;
PKT_public_key *pk_orig;
@ -788,6 +799,13 @@ import_one( const char *fname, KBNODE keyblock, struct stats_s *stats,
return 0;
}
if (filter && filter (pk, NULL, filter_arg))
{
log_error (_("key %s: %s\n"), keystr_from_pk(pk),
_("rejected by import filter"));
return 0;
}
if (opt.interactive) {
if(is_status_enabled())
print_import_check (pk, uidnode->pkt->pkt.user_id);
@ -1165,15 +1183,16 @@ sec_to_pub_keyblock(KBNODE sec_keyblock)
* with the trust calculation.
*/
static int
import_secret_one( const char *fname, KBNODE keyblock,
struct stats_s *stats, unsigned int options)
import_secret_one (const char *fname, KBNODE keyblock,
struct stats_s *stats, unsigned int options,
import_filter_t filter, void *filter_arg)
{
PKT_secret_key *sk;
KBNODE node, uidnode;
u32 keyid[2];
int rc = 0;
/* get the key and print some info about it */
/* Get the key and print some info about it. */
node = find_kbnode( keyblock, PKT_SECRET_KEY );
if( !node )
BUG();
@ -1182,6 +1201,12 @@ import_secret_one( const char *fname, KBNODE keyblock,
keyid_from_sk( sk, keyid );
uidnode = find_next_kbnode( keyblock, PKT_USER_ID );
if (filter && filter (NULL, sk, filter_arg)) {
log_error (_("secret key %s: %s\n"), keystr_from_sk(sk),
_("rejected by import filter"));
return 0;
}
if( opt.verbose )
{
log_info( "sec %4u%c/%s %s ",
@ -1260,8 +1285,9 @@ import_secret_one( const char *fname, KBNODE keyblock,
KBNODE pub_keyblock=sec_to_pub_keyblock(keyblock);
if(pub_keyblock)
{
import_one(fname,pub_keyblock,stats,
NULL,NULL,opt.import_options,1);
import_one (fname, pub_keyblock, stats,
NULL, NULL, opt.import_options, 1,
NULL, NULL);
release_kbnode(pub_keyblock);
}
}

71
g10/keyserver.c
View File

@ -981,9 +981,54 @@ direct_uri_map(const char *scheme,unsigned int is_direct)
#define KEYSERVER_ARGS_KEEP " -o \"%O\" \"%I\""
#define KEYSERVER_ARGS_NOKEEP " -o \"%o\" \"%i\""
/* Check whether a key matches the search description. The filter
returns 0 if the key shall be imported. Note that this kind of
filter is not related to the iobuf filters. */
static int
keyserver_spawn(enum ks_action action,strlist_t list,KEYDB_SEARCH_DESC *desc,
int count,int *prog,unsigned char **fpr,size_t *fpr_len,
keyserver_retrieval_filter (PKT_public_key *pk, PKT_secret_key *sk, void *arg)
{
KEYDB_SEARCH_DESC *desc = arg;
u32 keyid[2];
byte fpr[MAX_FINGERPRINT_LEN];
size_t fpr_len = 0;
/* Secret keys are not expected from a keyserver. Do not import. */
if (sk)
return G10ERR_GENERAL;
fingerprint_from_pk (pk, fpr, &fpr_len);
keyid_from_pk (pk, keyid);
/* Compare requested and returned fingerprints if available. */
if (desc->mode == KEYDB_SEARCH_MODE_FPR20)
{
if (fpr_len != 20 || memcmp (fpr, desc->u.fpr, 20))
return G10ERR_GENERAL;
}
else if (desc->mode == KEYDB_SEARCH_MODE_FPR16)
{
if (fpr_len != 16 || memcmp (fpr, desc->u.fpr, 16))
return G10ERR_GENERAL;
}
else if (desc->mode == KEYDB_SEARCH_MODE_LONG_KID)
{
if (keyid[0] != desc->u.kid[0] || keyid[1] != desc->u.kid[1])
return G10ERR_GENERAL;
}
else if (desc->mode == KEYDB_SEARCH_MODE_SHORT_KID)
{
if (keyid[1] != desc->u.kid[1])
return G10ERR_GENERAL;
}
return 0;
}
static int
keyserver_spawn (enum ks_action action, strlist_t list, KEYDB_SEARCH_DESC *desc,
int count, int *prog, unsigned char **fpr, size_t *fpr_len,
struct keyserver_spec *keyserver)
{
int ret=0,i,gotversion=0,outofband=0;
@ -1505,7 +1550,8 @@ keyserver_spawn(enum ks_action action,strlist_t list,KEYDB_SEARCH_DESC *desc,
import_keys_stream (spawn->fromchild, stats_handle, fpr, fpr_len,
(opt.keyserver_options.import_options
| IMPORT_NO_SECKEY));
| IMPORT_NO_SECKEY),
keyserver_retrieval_filter, desc);
import_print_stats(stats_handle);
import_release_stats_handle(stats_handle);
@ -1536,12 +1582,14 @@ keyserver_spawn(enum ks_action action,strlist_t list,KEYDB_SEARCH_DESC *desc,
return ret;
}
static int
keyserver_work(enum ks_action action,strlist_t list,KEYDB_SEARCH_DESC *desc,
int count,unsigned char **fpr,size_t *fpr_len,
keyserver_work (enum ks_action action, strlist_t list, KEYDB_SEARCH_DESC *desc,
int count, unsigned char **fpr, size_t *fpr_len,
struct keyserver_spec *keyserver)
{
int rc=0,ret=0;
int rc = 0;
int ret = 0;
if(!keyserver)
{
@ -1606,6 +1654,7 @@ keyserver_work(enum ks_action action,strlist_t list,KEYDB_SEARCH_DESC *desc,
#endif /* ! DISABLE_KEYSERVER_HELPERS*/
}
int
keyserver_export(strlist_t users)
{
@ -1638,6 +1687,7 @@ keyserver_export(strlist_t users)
return rc;
}
int
keyserver_import(strlist_t users)
{
@ -1712,11 +1762,14 @@ keyserver_import_keyid(u32 *keyid,struct keyserver_spec *keyserver)
return keyserver_work(KS_GET,NULL,&desc,1,NULL,NULL,keyserver);
}
/* code mostly stolen from do_export_stream */
/* Code mostly stolen from do_export_stream */
static int
keyidlist(strlist_t users,KEYDB_SEARCH_DESC **klist,int *count,int fakev3)
{
int rc=0,ndesc,num=100;
int rc = 0;
int num = 100;
int ndesc;
KBNODE keyblock=NULL,node;
KEYDB_HANDLE kdbhd;
KEYDB_SEARCH_DESC *desc;
@ -2045,7 +2098,7 @@ keyserver_import_cert(const char *name,unsigned char **fpr,size_t *fpr_len)
rc=import_keys_stream (key, NULL, fpr, fpr_len,
(opt.keyserver_options.import_options
| IMPORT_NO_SECKEY));
| IMPORT_NO_SECKEY), NULL, NULL);
opt.no_armor=armor_status;

9
g10/main.h
View File

@ -260,11 +260,16 @@ gcry_mpi_t encode_md_value( PKT_public_key *pk, PKT_secret_key *sk,
gcry_md_hd_t md, int hash_algo );
/*-- import.c --*/
typedef int (*import_filter_t)(PKT_public_key *pk, PKT_secret_key *sk,
void *arg);
int parse_import_options(char *str,unsigned int *options,int noisy);
void import_keys( char **fnames, int nnames,
void *stats_hd, unsigned int options );
int import_keys_stream( iobuf_t inp,void *stats_hd,unsigned char **fpr,
size_t *fpr_len,unsigned int options );
int import_keys_stream (iobuf_t inp, void *stats_hd, unsigned char **fpr,
size_t *fpr_len, unsigned int options,
import_filter_t filter, void *filter_arg);
void *import_new_stats_handle (void);
void import_release_stats_handle (void *p);
void import_print_stats (void *hd);