Add support for opaque PSKs to ssl_server2 example application
This commit adds command line parameters `psk_slot` and `psk_list_slot`
to the example application `programs/ssl/ssl_server2`. These have the
following semantics:
- `psk_slot`: The same semantics as for the `ssl_client2` example
application. That is, if a PSK is configured through the use
of the command line parameters `psk` and `psk_identity`, then
`psk_slot=X` can be used to import the PSK into PSA key slot X
and registering it statically with the SSL configuration through
the new API call mbedtls_ssl_conf_hs_opaque().
- `psk_list_slot`: In addition to the static PSK registered in the
the SSL configuration, servers can register a callback for picking
the PSK corresponding to the PSK identity that the client chose.
The `ssl_server2` example application uses such a callback to select
the PSK from a list of PSKs + Identities provided through the
command line parameter `psk_list`, and to register the selected
PSK via `mbedtls_ssl_set_hs_psk()`. In this case, the new parameter
`psk_list_slot=X` has the effect of registering all PSKs provided in
in `psk_list` as PSA keys in the key slots starting from slot `X`,
and having the PSK selection callback register the chosen PSK
through the new API function `mbedtls_ssl_set_hs_psk_opaque()`.
diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 1c6ccae..1169763 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -123,6 +123,8 @@
#define DFL_ASYNC_PRIVATE_DELAY2 ( -1 )
#define DFL_ASYNC_PRIVATE_ERROR ( 0 )
#define DFL_PSK ""
+#define DFL_PSK_SLOT 0
+#define DFL_PSK_LIST_SLOT 0
#define DFL_PSK_IDENTITY "Client_identity"
#define DFL_ECJPAKE_PW NULL
#define DFL_PSK_LIST NULL
@@ -224,9 +226,38 @@
#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
-#define USAGE_PSK \
+#define USAGE_PSK_RAW \
" psk=%%s default: \"\" (in hex, without 0x)\n" \
- " psk_identity=%%s default: \"Client_identity\"\n"
+ " psk_identity=%%s default: \"Client_identity\"\n" \
+ " psk_list=%%s default: \"\"\n" \
+ " A list of (PSK identity, PSK value) pairs in (hex format, without 0x)\n" \
+ " id1,psk1[,id2,psk2[,...]]\n"
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+#define USAGE_PSK_SLOT \
+ " psk_slot=%%d default: 0 (don't use key slots)\n" \
+ " An empty key slot identifier to be used to hold the static PSK\n" \
+ " configured through the psk parameter.\n"\
+ " Note: Currently only supported in conjunction with\n" \
+ " the use of min_version to force TLS 1.2 and force_ciphersuite \n" \
+ " to force a particular PSK-only ciphersuite.\n" \
+ " Note: This is to test integration of PSA-based opaque PSKs with\n" \
+ " Mbed TLS only. Production systems are likely to configure Mbed TLS\n" \
+ " with prepopulated key slots instead of importing raw key material.\n" \
+ " psk_list_slot=%%d default: 0 (don't use key slots)\n" \
+ " The base of a consecutive list of empty key slot identifiers to be used\n" \
+ " to hold the dynamic PSKs configured through the psk_list parameter;\n" \
+ " for example, if you specify a list of 3 dynamic PSKs through the psk_list\n"\
+ " parameter, then the slots psk_slot, .., psk_slot+3 must be empty.\n" \
+ " Note: Currently only supported in conjunction with\n" \
+ " the use of min_version to force TLS 1.2 and force_ciphersuite \n" \
+ " to force a particular PSK-only ciphersuite.\n" \
+ " Note: This is to test integration of PSA-based opaque PSKs with\n" \
+ " Mbed TLS only. Production systems are likely to configure Mbed TLS\n" \
+ " with prepopulated key slots instead of importing raw key material.\n"
+#else
+#define USAGE_PSK_SLOT ""
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+#define USAGE_PSK USAGE_PSK_RAW USAGE_PSK_SLOT
#else
#define USAGE_PSK ""
#endif /* MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED */
@@ -453,6 +484,10 @@
int async_private_delay1; /* number of times f_async_resume needs to be called for key 1, or -1 for no async */
int async_private_delay2; /* number of times f_async_resume needs to be called for key 2, or -1 for no async */
int async_private_error; /* inject error in async private callback */
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ int psk_slot;
+ int psk_list_slot;
+#endif
const char *psk; /* the pre-shared key */
const char *psk_identity; /* the pre-shared key identity */
char *psk_list; /* list of PSK id/key pairs for callback */
@@ -771,6 +806,9 @@
const char *name;
size_t key_len;
unsigned char key[MBEDTLS_PSK_MAX_LEN];
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ psa_key_slot_t slot;
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
psk_entry *next;
};
@@ -819,6 +857,11 @@
if( unhexify( new->key, key_hex, &new->key_len ) != 0 )
goto error;
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ if( opt.psk_list_slot != 0 )
+ new->slot = opt.psk_list_slot++;
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
new->next = cur;
cur = new;
}
@@ -844,6 +887,11 @@
if( name_len == strlen( cur->name ) &&
memcmp( name, cur->name, name_len ) == 0 )
{
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ if( cur->slot != 0 )
+ return( mbedtls_ssl_set_hs_psk_opaque( ssl, cur->slot ) );
+ else
+#endif
return( mbedtls_ssl_set_hs_psk( ssl, cur->key, cur->key_len ) );
}
@@ -1174,12 +1222,39 @@
return( 0 );
}
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+static psa_status_t psa_setup_psk_key_slot( psa_key_slot_t slot,
+ psa_algorithm_t alg,
+ unsigned char *psk,
+ size_t psk_len )
+{
+ psa_status_t status;
+ psa_key_policy_t policy;
+
+ psa_key_policy_init( &policy );
+ psa_key_policy_set_usage( &policy, PSA_KEY_USAGE_DERIVE, alg );
+
+ status = psa_set_key_policy( slot, &policy );
+ if( status != PSA_SUCCESS )
+ return( status );
+
+ status = psa_import_key( slot, PSA_KEY_TYPE_DERIVE, psk, psk_len );
+ if( status != PSA_SUCCESS )
+ return( status );
+
+ return( PSA_SUCCESS );
+}
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
int main( int argc, char *argv[] )
{
int ret = 0, len, written, frags, exchanges_left;
int version_suites[4][2];
unsigned char* buf = 0;
#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ psa_algorithm_t alg = 0;
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
unsigned char psk[MBEDTLS_PSK_MAX_LEN];
size_t psk_len = 0;
psk_entry *psk_info = NULL;
@@ -1342,6 +1417,10 @@
opt.async_private_delay2 = DFL_ASYNC_PRIVATE_DELAY2;
opt.async_private_error = DFL_ASYNC_PRIVATE_ERROR;
opt.psk = DFL_PSK;
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ opt.psk_slot = DFL_PSK_SLOT;
+ opt.psk_list_slot = DFL_PSK_LIST_SLOT;
+#endif
opt.psk_identity = DFL_PSK_IDENTITY;
opt.psk_list = DFL_PSK_LIST;
opt.ecjpake_pw = DFL_ECJPAKE_PW;
@@ -1470,6 +1549,12 @@
#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
else if( strcmp( p, "psk" ) == 0 )
opt.psk = q;
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ else if( strcmp( p, "psk_slot" ) == 0 )
+ opt.psk_slot = atoi( q );
+ else if( strcmp( p, "psk_list_slot" ) == 0 )
+ opt.psk_list_slot = atoi( q );
+#endif
else if( strcmp( p, "psk_identity" ) == 0 )
opt.psk_identity = q;
else if( strcmp( p, "psk_list" ) == 0 )
@@ -1779,6 +1864,42 @@
goto exit;
}
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ if( opt.psk_slot != 0 )
+ {
+ if( strlen( opt.psk ) == 0 )
+ {
+ mbedtls_printf( "psk_slot set but no psk to be imported specified.\n" );
+ ret = 2;
+ goto usage;
+ }
+
+ if( opt.force_ciphersuite[0] <= 0 )
+ {
+ mbedtls_printf( "opaque PSKs are only supported in conjunction with forcing TLS 1.2 and a PSK-only ciphersuite through the 'force_ciphersuite' option.\n" );
+ ret = 2;
+ goto usage;
+ }
+ }
+
+ if( opt.psk_list_slot != 0 )
+ {
+ if( opt.psk_list == NULL )
+ {
+ mbedtls_printf( "psk_slot set but no psk to be imported specified.\n" );
+ ret = 2;
+ goto usage;
+ }
+
+ if( opt.force_ciphersuite[0] <= 0 )
+ {
+ mbedtls_printf( "opaque PSKs are only supported in conjunction with forcing TLS 1.2 and a PSK-only ciphersuite through the 'force_ciphersuite' option.\n" );
+ ret = 2;
+ goto usage;
+ }
+ }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
if( opt.force_ciphersuite[0] > 0 )
{
const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
@@ -1828,6 +1949,30 @@
opt.arc4 = MBEDTLS_SSL_ARC4_ENABLED;
}
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ if( opt.psk_slot != 0 || opt.psk_list_slot != 0 )
+ {
+ /* Ensure that the chosen ciphersuite is PSK-only; we must know
+ * the ciphersuite in advance to set the correct policy for the
+ * PSK key slot. This limitation might go away in the future. */
+ if( ciphersuite_info->key_exchange != MBEDTLS_KEY_EXCHANGE_PSK ||
+ opt.min_version != MBEDTLS_SSL_MINOR_VERSION_3 )
+ {
+ mbedtls_printf( "opaque PSKs are only supported in conjunction with forcing TLS 1.2 and a PSK-only ciphersuite through the 'force_ciphersuite' option.\n" );
+ ret = 2;
+ goto usage;
+ }
+
+ /* Determine KDF algorithm the opaque PSK will be used in. */
+#if defined(MBEDTLS_SHA512_C)
+ if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
+ alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_384);
+ else
+#endif /* MBEDTLS_SHA512_C */
+ alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_256);
+ }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
}
if( opt.version_suites != NULL )
@@ -2501,12 +2646,35 @@
#endif
#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
+
if( strlen( opt.psk ) != 0 && strlen( opt.psk_identity ) != 0 )
{
- ret = mbedtls_ssl_conf_psk( &conf, psk, psk_len,
- (const unsigned char *) opt.psk_identity,
- strlen( opt.psk_identity ) );
- if( ret != 0 )
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ if( opt.psk_slot != 0 )
+ {
+ /* The algorithm has already been determined earlier. */
+ status = psa_setup_psk_key_slot( opt.psk_slot, alg,
+ psk, psk_len );
+ if( status != PSA_SUCCESS )
+ {
+ ret = MBEDTLS_ERR_SSL_HW_ACCEL_FAILED;
+ goto exit;
+ }
+
+ if( ( ret = mbedtls_ssl_conf_psk_opaque( &conf, opt.psk_slot,
+ (const unsigned char *) opt.psk_identity,
+ strlen( opt.psk_identity ) ) ) != 0 )
+ {
+ mbedtls_printf( " failed\n ! mbedtls_ssl_conf_psk_opaque returned %d\n\n",
+ ret );
+ goto exit;
+ }
+ }
+ else
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+ if( ( ret = mbedtls_ssl_conf_psk( &conf, psk, psk_len,
+ (const unsigned char *) opt.psk_identity,
+ strlen( opt.psk_identity ) ) ) != 0 )
{
mbedtls_printf( " failed\n mbedtls_ssl_conf_psk returned -0x%04X\n\n", - ret );
goto exit;
@@ -2514,7 +2682,28 @@
}
if( opt.psk_list != NULL )
+ {
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ if( opt.psk_list_slot != 0 )
+ {
+ psk_entry *cur_psk;
+ for( cur_psk = psk_info; cur_psk != NULL; cur_psk = cur_psk->next )
+ {
+ fprintf( stderr, "REGISTER KEY SLOT %d\n", (int) cur_psk->slot );
+ status = psa_setup_psk_key_slot( cur_psk->slot, alg,
+ cur_psk->key,
+ cur_psk->key_len );
+ if( status != PSA_SUCCESS )
+ {
+ fprintf( stderr, "REGISTER KEY SLOT\n" );
+ ret = MBEDTLS_ERR_SSL_HW_ACCEL_FAILED;
+ goto exit;
+ }
+ }
+ }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
mbedtls_ssl_conf_psk_cb( &conf, psk_callback, psk_info );
+ }
#endif
#if defined(MBEDTLS_DHM_C)
