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Screen keyserver responses.

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* g10/main.h: Typedef import_filter for filter callbacks.
* 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.
This commit is contained in:
Stefan Tomanek 2014-01-30 00:57:43 +01:00 • committed by Werner Koch
parent 8eab483a1c
commit 5230304349
3 changed files with 116 additions and 39 deletions
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86
g10/keyserver.c
View file

@ -656,7 +656,7 @@ parse_keyrec(char *keystring)
case 'R':
work->flags|=1;
break;
case 'd':
case 'D':
work->flags|=2;
@ -910,7 +910,7 @@ keyserver_search_prompt(IOBUF buffer,const char *searchstr)
/* Leave this commented out or now, and perhaps for a very long
time. All HKPish servers return HTML error messages for
no-key-found. */
/*
/*
if(!started)
log_info(_("keyserver does not support searching\n"));
else
@ -959,7 +959,52 @@ direct_uri_map(const char *scheme,unsigned int is_direct)
#define KEYSERVER_ARGS_KEEP " -o \"%O\" \"%I\""
#define KEYSERVER_ARGS_NOKEEP " -o \"%o\" \"%i\""
static int
/* 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_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 list,KEYDB_SEARCH_DESC *desc,
int count,int *prog,unsigned char **fpr,size_t *fpr_len,
struct keyserver_spec *keyserver)
@ -999,7 +1044,7 @@ keyserver_spawn(enum ks_action action,STRLIST list,KEYDB_SEARCH_DESC *desc,
the program of this process lives. Fortunately Windows provides
a way to retrieve this and our get_libexecdir function has been
modified to return just this. Setting the exec-path is not
anymore required.
anymore required.
set_exec_path(libexecdir);
*/
#else
@ -1031,7 +1076,7 @@ keyserver_spawn(enum ks_action action,STRLIST list,KEYDB_SEARCH_DESC *desc,
fetcher that can speak that protocol (this is a problem for
LDAP). */
strcat(command,GPGKEYS_PREFIX);
strcat(command,GPGKEYS_PREFIX);
strcat(command,scheme);
/* This "_uri" thing is in case we need to call a direct handler
@ -1061,7 +1106,7 @@ keyserver_spawn(enum ks_action action,STRLIST list,KEYDB_SEARCH_DESC *desc,
{
command=xrealloc(command,strlen(command)+
strlen(KEYSERVER_ARGS_NOKEEP)+1);
strcat(command,KEYSERVER_ARGS_NOKEEP);
strcat(command,KEYSERVER_ARGS_NOKEEP);
}
ret=exec_write(&spawn,NULL,command,NULL,0,0);
@ -1509,8 +1554,9 @@ keyserver_spawn(enum ks_action action,STRLIST 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);
@ -1541,7 +1587,7 @@ keyserver_spawn(enum ks_action action,STRLIST list,KEYDB_SEARCH_DESC *desc,
return ret;
}
static int
static int
keyserver_work(enum ks_action action,STRLIST list,KEYDB_SEARCH_DESC *desc,
int count,unsigned char **fpr,size_t *fpr_len,
struct keyserver_spec *keyserver)
@ -1611,7 +1657,7 @@ keyserver_work(enum ks_action action,STRLIST list,KEYDB_SEARCH_DESC *desc,
#endif /* ! DISABLE_KEYSERVER_HELPERS*/
}
int
int
keyserver_export(STRLIST users)
{
STRLIST sl=NULL;
@ -1643,7 +1689,7 @@ keyserver_export(STRLIST users)
return rc;
}
int
int
keyserver_import(STRLIST users)
{
KEYDB_SEARCH_DESC *desc;
@ -1703,7 +1749,7 @@ keyserver_import_fprint(const byte *fprint,size_t fprint_len,
return keyserver_work(KS_GET,NULL,&desc,1,NULL,NULL,keyserver);
}
int
int
keyserver_import_keyid(u32 *keyid,struct keyserver_spec *keyserver)
{
KEYDB_SEARCH_DESC desc;
@ -1718,7 +1764,7 @@ keyserver_import_keyid(u32 *keyid,struct keyserver_spec *keyserver)
}
/* code mostly stolen from do_export_stream */
static int
static int
keyidlist(STRLIST users,KEYDB_SEARCH_DESC **klist,int *count,int fakev3)
{
int rc=0,ndesc,num=100;
@ -1741,10 +1787,10 @@ keyidlist(STRLIST users,KEYDB_SEARCH_DESC **klist,int *count,int fakev3)
}
else
{
for (ndesc=0, sl=users; sl; sl = sl->next, ndesc++)
for (ndesc=0, sl=users; sl; sl = sl->next, ndesc++)
;
desc = xmalloc ( ndesc * sizeof *desc);
for (ndesc=0, sl=users; sl; sl = sl->next)
{
if(classify_user_id (sl->d, desc+ndesc))
@ -1757,7 +1803,7 @@ keyidlist(STRLIST users,KEYDB_SEARCH_DESC **klist,int *count,int fakev3)
while (!(rc = keydb_search (kdbhd, desc, ndesc)))
{
if (!users)
if (!users)
desc[0].mode = KEYDB_SEARCH_MODE_NEXT;
/* read the keyblock */
@ -1860,7 +1906,7 @@ keyidlist(STRLIST users,KEYDB_SEARCH_DESC **klist,int *count,int fakev3)
if(rc==-1)
rc=0;
leave:
if(rc)
xfree(*klist);
@ -2043,7 +2089,7 @@ 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;
@ -2182,7 +2228,7 @@ keyserver_import_ldap(const char *name,unsigned char **fpr,size_t *fpr_len)
snprintf(port,7,":%u",srvlist[i].port);
strcat(keyserver->host,port);
}
strcat(keyserver->host," ");
}
@ -2198,7 +2244,7 @@ keyserver_import_ldap(const char *name,unsigned char **fpr,size_t *fpr_len)
strcat(keyserver->host,domain);
append_to_strlist(&list,name);
rc=keyserver_work(KS_GETNAME,list,NULL,0,fpr,fpr_len,keyserver);
free_strlist(list);