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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
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77
g10/keyserver.c
View file

@ -981,10 +981,55 @@ 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,
struct keyserver_spec *keyserver)
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;
strlist_t temp;
@ -1504,8 +1549,9 @@ keyserver_spawn(enum ks_action action,strlist_t list,KEYDB_SEARCH_DESC *desc,
but we better protect against rogue keyservers. */
import_keys_stream (spawn->fromchild, stats_handle, fpr, fpr_len,
(opt.keyserver_options.import_options
| IMPORT_NO_SECKEY));
(opt.keyserver_options.import_options
| 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,
struct keyserver_spec *keyserver)
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;