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gnupg/g10/passphrase.c

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/* passphrase.c - Get a passphrase
* Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
#include <assert.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
#include <errno.h>
#include <gcrypt.h>
#include "util.h"
#include "options.h"
#include "ttyio.h"
#include "keydb.h"
#include "main.h"
#include "i18n.h"
#include "status.h"
#include "gpga-prot.h"
#define buftou32( p ) ((*(byte*)(p) << 24) | (*((byte*)(p)+1)<< 16) | \
(*((byte*)(p)+2) << 8) | (*((byte*)(p)+3)))
#define u32tobuf( p, a ) do { \
((byte*)p)[0] = (byte)((a) >> 24); \
((byte*)p)[1] = (byte)((a) >> 16); \
((byte*)p)[2] = (byte)((a) >> 8); \
((byte*)p)[3] = (byte)((a) ); \
} while(0)
static char *fd_passwd = NULL;
static char *next_pw = NULL;
static char *last_pw = NULL;
static void hash_passphrase( DEK *dek, char *pw, STRING2KEY *s2k, int create );
int
have_static_passphrase()
{
if ( opt.use_agent )
return 0;
return !!fd_passwd;
}
/****************
* Set the passphrase to be used for the next query and only for the next
* one.
*/
void
set_next_passphrase( const char *s )
{
gcry_free(next_pw);
next_pw = NULL;
if( s ) {
next_pw = gcry_xmalloc_secure( strlen(s)+1 );
strcpy(next_pw, s );
}
}
/****************
* Get the last passphrase used in passphrase_to_dek.
* Note: This removes the passphrase from this modules and
* the caller must free the result. May return NULL:
*/
char *
get_last_passphrase()
{
char *p = last_pw;
last_pw = NULL;
return p;
}
void
read_passphrase_from_fd( int fd )
{
int i, len;
char *pw;
if ( opt.use_agent )
return; /* not used here */
if( !opt.batch )
tty_printf("Reading passphrase from file descriptor %d ...", fd );
for( pw = NULL, i = len = 100; ; i++ ) {
if( i >= len-1 ) {
char *pw2 = pw;
len += 100;
pw = gcry_xmalloc_secure( len );
if( pw2 )
memcpy(pw, pw2, i );
else
i=0;
}
if( read( fd, pw+i, 1) != 1 || pw[i] == '\n' )
break;
}
pw[i] = 0;
if( !opt.batch )
tty_printf("\b\b\b \n" );
gcry_free( fd_passwd );
fd_passwd = pw;
}
static int
writen ( int fd, const void *buf, size_t nbytes )
{
size_t nleft = nbytes;
ssize_t nwritten;
while( nleft > 0 ) {
nwritten = write( fd, buf, nleft );
if( nwritten < 0 ) {
if ( errno == EINTR )
nwritten = 0;
else {
log_error ( "writen() failed: %s\n", strerror (errno) );
return -1;
}
}
nleft -= nwritten;
buf = (const char*)buf + nwritten;
}
return 0;
}
static int
readn ( int fd, void *buf, size_t buflen, size_t *ret_nread )
{
size_t nleft = buflen;
int nread;
char *p;
p = buf;
while( nleft > 0 ) {
nread = read ( fd, buf, nleft );
if( nread < 0 ) {
if (nread == EINTR)
nread = 0;
else {
log_error ( "read() error: %s\n", strerror (errno) );
return -1;
}
}
else if( !nread )
break; /* EOF */
nleft -= nread;
buf = (char*)buf + nread;
}
if( ret_nread )
*ret_nread = buflen - nleft;
return 0;
}
/*
* Open a connection to the agent and send the magic string
* Returns: -1 on error or an filedescriptor for urther processing
*/
static int
agent_open ()
{
int fd;
char *infostr, *p;
struct sockaddr_un client_addr;
size_t len;
infostr = getenv ( "GPG_AGENT_INFO" );
if ( !infostr ) {
log_error (_("gpg-agent is not available in this session\n"));
return -1;
}
infostr = gcry_xstrdup ( infostr );
if ( !(p = strchr ( infostr, ':')) || p == infostr
|| (p-infostr)+1 >= sizeof client_addr.sun_path ) {
log_error (_("malformed GPG_AGENT_INFO environment variable\n"));
gcry_free (infostr );
return -1;
}
*p = 0;
if( (fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1 ) {
log_error ("can't create socket: %s\n", strerror(errno) );
gcry_free (infostr );
return -1;
}
memset( &client_addr, 0, sizeof client_addr );
client_addr.sun_family = AF_UNIX;
strcpy( client_addr.sun_path, infostr );
len = offsetof (struct sockaddr_un, sun_path)
+ strlen(client_addr.sun_path) + 1;
if( connect( fd, (struct sockaddr*)&client_addr, len ) == -1 ) {
log_error ( _("can't connect to `%s': %s\n"),
infostr, strerror (errno) );
gcry_free (infostr );
close (fd );
return -1;
}
gcry_free (infostr);
if ( writen ( fd, "GPGA\0\0\0\x01", 8 ) ) {
close (fd);
fd = -1;
}
return fd;
}
static void
agent_close ( int fd )
{
close (fd);
}
/*
* Ask the GPG Agent for the passphrase.
* Mode 0: Allow cached passphrase
* 1: No cached passphrase FIXME: Not really implemented
* 2: Ditto, but change the text to "repeat entry"
*/
static char *
agent_get_passphrase ( u32 *keyid, int mode )
{
size_t n;
char *atext;
char buf[50];
int fd = -1;
int nread;
u32 reply;
char *pw = NULL;
PKT_public_key *pk = gcry_xcalloc( 1, sizeof *pk );
byte fpr[MAX_FINGERPRINT_LEN];
#if MAX_FINGERPRINT_LEN < 20
#error agent needs a 20 byte fingerprint
#endif
memset (fpr, 0, MAX_FINGERPRINT_LEN );
if( keyid && get_pubkey( pk, keyid ) )
pk = NULL; /* oops: no key for some reason */
if ( !mode && pk ) {
char *uid;
size_t uidlen;
const char *algo_name = gcry_pk_algo_name( pk->pubkey_algo );
const char *timestr;
char *maink;
const char *fmtstr;
if ( !algo_name )
algo_name = "?";
fmtstr = _(" (main key ID %08lX)");
maink = gcry_xmalloc ( strlen (fmtstr) + 20 );
if( keyid[2] && keyid[3] && keyid[0] != keyid[2]
&& keyid[1] != keyid[3] )
sprintf( maink, fmtstr, (ulong)keyid[3] );
else
*maink = 0;
uid = get_user_id( keyid, &uidlen );
timestr = strtimestamp (pk->timestamp);
fmtstr = _("You need a passphrase to unlock the"
" secret key for user:\n"
"\"%.*s\"\n"
"%u-bit %s key, ID %08lX, created %s%s\n" );
atext = gcry_xmalloc ( 100 + strlen (fmtstr)
+ uidlen + 15 + strlen(algo_name) + 8
+ strlen (timestr) + strlen (maink) );
sprintf (atext, fmtstr,
uidlen, uid,
nbits_from_pk (pk), algo_name, (ulong)keyid[1], timestr,
maink );
gcry_free (uid);
gcry_free (maink);
{
size_t dummy;
fingerprint_from_pk( pk, fpr, &dummy );
}
}
else if (mode == 1 )
atext = gcry_xstrdup ( _("Enter passphrase\n") );
else
atext = gcry_xstrdup ( _("Repeat passphrase\n") );
if ( (fd = agent_open ()) == -1 )
goto failure;
n = 4 + 20 + strlen (atext);
u32tobuf (buf, n );
u32tobuf (buf+4, GPGA_PROT_GET_PASSPHRASE );
memcpy (buf+8, fpr, 20 );
if ( writen ( fd, buf, 28 ) || writen ( fd, atext, strlen (atext) ) )
goto failure;
gcry_free (atext); atext = NULL;
/* get response */
if ( readn ( fd, buf, 12, &nread ) )
goto failure;
if ( nread < 8 ) {
log_error ( _("response from agent too short\n") );
goto failure;
}
n = buftou32 ( buf );
reply = buftou32 ( buf + 4 );
if ( reply == GPGA_PROT_GOT_PASSPHRASE ) {
size_t pwlen;
size_t nn;
if ( nread < 12 || n < 8 ) {
log_error ( _("response from agent too short\n") );
goto failure;
}
pwlen = buftou32 ( buf + 8 );
nread -= 12;
n -= 8;
if ( pwlen > n || n > 1000 ) {
log_error (_("passphrase too long\n"));
/* or protocol error */
goto failure;
}
/* we read the whole block in one chunk to give no hints
* on how long the passhrase actually is - this wastes some bytes
* but because we already have this padding we should not loosen
* the by issuing 2 read calls */
pw = gcry_xmalloc_secure ( n+1 );
if ( readn ( fd, pw, n, &nn ) )
goto failure;
if ( n != nn ) {
log_error (_("invalid response from agent\n"));
goto failure;
}
pw[pwlen] = 0; /* make a C String */
agent_close (fd);
free_public_key( pk );
return pw;
}
else if ( reply == GPGA_PROT_CANCELED ) {
log_info ( _("cancelled by user\n") );
}
else {
log_error ( _("problem with the agent: agent returns 0x%lx\n"),
(ulong)reply );
}
failure:
gcry_free (atext);
if ( fd != -1 )
agent_close (fd);
gcry_free (pw );
free_public_key( pk );
return NULL;
}
/*
* Reste the cached passphrase
*/
void
passphrase_clear_cache ( u32 *keyid, int algo )
{
size_t n;
char buf[50];
int fd = -1;
int nread;
u32 reply;
PKT_public_key *pk = gcry_xcalloc( 1, sizeof *pk );
byte fpr[MAX_FINGERPRINT_LEN];
#if MAX_FINGERPRINT_LEN < 20
#error agent needs a 20 byte fingerprint
#endif
memset (fpr, 0, MAX_FINGERPRINT_LEN );
if( !keyid || get_pubkey( pk, keyid ) ) {
log_debug ("oops, no key in passphrase_clear_cache\n");
goto failure; /* oops: no key for some reason */
}
{
size_t dummy;
fingerprint_from_pk( pk, fpr, &dummy );
}
if ( (fd = agent_open ()) == -1 )
goto failure;
n = 4 + 20;
u32tobuf (buf, n );
u32tobuf (buf+4, GPGA_PROT_CLEAR_PASSPHRASE );
memcpy (buf+8, fpr, 20 );
if ( writen ( fd, buf, 28 ) )
goto failure;
/* get response */
if ( readn ( fd, buf, 8, &nread ) )
goto failure;
if ( nread < 8 ) {
log_error ( _("response from agent too short\n") );
goto failure;
}
reply = buftou32 ( buf + 4 );
if ( reply != GPGA_PROT_OKAY && reply != GPGA_PROT_NO_PASSPHRASE ) {
log_error ( _("problem with the agent: agent returns 0x%lx\n"),
(ulong)reply );
}
failure:
if ( fd != -1 )
agent_close (fd);
free_public_key( pk );
}
/****************
* Get a passphrase for the secret key with KEYID, display TEXT
* if the user needs to enter the passphrase.
* mode 0 = standard, 2 = create new passphrase
* Returns: a DEK with a session key; caller must free
* or NULL if the passphrase was not correctly repeated.
* (only for mode 2)
* a dek->keylen of 0 means: no passphrase entered.
* (only for mode 2)
* pubkey_algo is only informational.
*/
DEK *
passphrase_to_dek( u32 *keyid, int pubkey_algo,
int cipher_algo, STRING2KEY *s2k, int mode )
{
char *pw = NULL;
DEK *dek;
STRING2KEY help_s2k;
if( !s2k ) {
s2k = &help_s2k;
s2k->mode = 0;
/* this should be MD5 if cipher is IDEA, but because we do
* not have IDEA, we use the default one, the user
* can select it from the commandline
*/
s2k->hash_algo = opt.def_digest_algo?opt.def_digest_algo
:DEFAULT_DIGEST_ALGO;
}
if( !next_pw && is_status_enabled() ) {
char buf[50];
if( keyid ) {
sprintf( buf, "%08lX%08lX", (ulong)keyid[0], (ulong)keyid[1] );
if( keyid[2] && keyid[3] && keyid[0] != keyid[2]
&& keyid[1] != keyid[3] )
sprintf( buf+strlen(buf), " %08lX%08lX %d 0",
(ulong)keyid[2], (ulong)keyid[3], pubkey_algo );
write_status_text( STATUS_NEED_PASSPHRASE, buf );
}
else {
sprintf( buf, "%d %d %d", cipher_algo, s2k->mode, s2k->hash_algo );
write_status_text( STATUS_NEED_PASSPHRASE_SYM, buf );
}
}
if( keyid && !opt.batch && !next_pw ) {
PKT_public_key *pk = gcry_xcalloc( 1, sizeof *pk );
size_t n;
char *p;
tty_printf(_("\nYou need a passphrase to unlock the secret key for\n"
"user: \"") );
p = get_user_id( keyid, &n );
tty_print_utf8_string( p, n );
gcry_free(p);
tty_printf("\"\n");
if( !get_pubkey( pk, keyid ) ) {
const char *s = gcry_pk_algo_name( pk->pubkey_algo );
tty_printf( _("%u-bit %s key, ID %08lX, created %s"),
nbits_from_pk( pk ), s?s:"?", (ulong)keyid[1],
strtimestamp(pk->timestamp) );
if( keyid[2] && keyid[3] && keyid[0] != keyid[2]
&& keyid[1] != keyid[3] )
tty_printf( _(" (main key ID %08lX)"), (ulong)keyid[3] );
tty_printf("\n");
}
tty_printf("\n");
free_public_key( pk );
}
if( next_pw ) {
pw = next_pw;
next_pw = NULL;
}
else if ( opt.use_agent ) {
pw = agent_get_passphrase ( keyid, mode == 2? 1: 0 );
if ( !pw )
pw = gcry_xstrdup ("");
if( *pw && mode == 2 ) {
char *pw2 = agent_get_passphrase ( keyid, 2 );
if ( !pw2 )
pw2 = gcry_xstrdup ("");
if( strcmp(pw, pw2) ) {
gcry_free(pw2);
gcry_free(pw);
return NULL;
}
gcry_free(pw2);
}
}
else if( fd_passwd ) {
pw = gcry_xmalloc_secure( strlen(fd_passwd)+1 );
strcpy( pw, fd_passwd );
}
else if( opt.batch ) {
log_error(_("can't query password in batchmode\n"));
pw = gcry_xstrdup( "" ); /* return an empty passphrase */
}
else {
pw = cpr_get_hidden("passphrase.enter", _("Enter passphrase: ") );
tty_kill_prompt();
if( mode == 2 && !cpr_enabled() ) {
char *pw2 = cpr_get_hidden("passphrase.repeat",
_("Repeat passphrase: ") );
tty_kill_prompt();
if( strcmp(pw, pw2) ) {
gcry_free(pw2);
gcry_free(pw);
return NULL;
}
gcry_free(pw2);
}
}
if( !pw || !*pw )
write_status( STATUS_MISSING_PASSPHRASE );
dek = gcry_xmalloc_secure( sizeof *dek );
dek->algo = cipher_algo;
if( !*pw && mode == 2 )
dek->keylen = 0;
else
hash_passphrase( dek, pw, s2k, mode==2 );
gcry_free(last_pw);
last_pw = pw;
return dek;
}
/****************
* Hash a passphrase using the supplied s2k. If create is true, create
* a new salt or what else must be filled into the s2k for a new key.
* always needs: dek->algo, s2k->mode, s2k->hash_algo.
*/
static void
hash_passphrase( DEK *dek, char *pw, STRING2KEY *s2k, int create )
{
GCRY_MD_HD md;
int pass, i;
int used = 0;
int pwlen = strlen(pw);
assert( s2k->hash_algo );
dek->keylen = gcry_cipher_get_algo_keylen( dek->algo );
if( !(dek->keylen > 0 && dek->keylen <= DIM(dek->key)) )
BUG();
if( !(md = gcry_md_open( s2k->hash_algo, GCRY_MD_FLAG_SECURE )) )
BUG();
for(pass=0; used < dek->keylen ; pass++ ) {
if( pass ) {
gcry_md_reset(md);
for(i=0; i < pass; i++ ) /* preset the hash context */
gcry_md_putc(md, 0 );
}
if( s2k->mode == 1 || s2k->mode == 3 ) {
int len2 = pwlen + 8;
ulong count = len2;
if( create && !pass ) {
gcry_randomize(s2k->salt, 8, GCRY_STRONG_RANDOM );
if( s2k->mode == 3 )
s2k->count = 96; /* 65536 iterations */
}
if( s2k->mode == 3 ) {
count = (16ul + (s2k->count & 15)) << ((s2k->count >> 4) + 6);
if( count < len2 )
count = len2;
}
/* a little bit complicated because we need a ulong for count */
while( count > len2 ) { /* maybe iterated+salted */
gcry_md_write( md, s2k->salt, 8 );
gcry_md_write( md, pw, pwlen );
count -= len2;
}
if( count < 8 )
gcry_md_write( md, s2k->salt, count );
else {
gcry_md_write( md, s2k->salt, 8 );
count -= 8;
gcry_md_write( md, pw, count );
}
}
else
gcry_md_write( md, pw, pwlen );
gcry_md_final( md );
i = gcry_md_get_algo_dlen( s2k->hash_algo );
if( i > dek->keylen - used )
i = dek->keylen - used;
memcpy( dek->key+used, gcry_md_read(md, s2k->hash_algo), i );
used += i;
}
gcry_md_close(md);
}
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