Fix documentation of what functions restart when

The previous comment in ecp.h that only functions that take a "restart
context" argument can restart was wrong due to ECDH and SSL functions.
Changing that criterion to "document says if can return IN PROGRESS".

This requires updating the documentation of the SSL functions to mention this
explicitly, but it's something we really ought to do anyway, a bit
embarrassing that this wasn't done already - callers need to know what
`MBEDTLS_ERR_SSL_xxx` error codes to special-case. Note that the documentation
of the relevant functions was in a suboptimal state, so it was improved in the
process - it could use some more improvement, but only the changes that helped
cleanly insert the info about the IN_PROGRESS part were done here.

Also, while updating the ecp.h comment, I noticed several functions in the
ECDH module were wrongfully documented as restartable, which is probably a
left-over from the days before `mbedtls_ecdh_enable_restart()` was introduced.
Fixing that as well, to make the criterion used in ecp.h correct.
This commit is contained in:
Manuel Pégourié-Gonnard 2018-10-15 13:29:21 +02:00
parent f0bbd7e3fd
commit 32df91183e
3 changed files with 131 additions and 74 deletions

View File

@ -91,8 +91,6 @@ mbedtls_ecdh_context;
* \param p_rng The RNG context.
*
* \return \c 0 on success.
* \return #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
* operations was reached: see \c mbedtls_ecp_set_max_ops().
* \return Another \c MBEDTLS_ERR_ECP_XXX or
* \c MBEDTLS_MPI_XXX error code on failure.
*/
@ -121,8 +119,6 @@ int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp
* \param p_rng The RNG context.
*
* \return \c 0 on success.
* \return #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
* operations was reached: see \c mbedtls_ecp_set_max_ops().
* \return Another \c MBEDTLS_ERR_ECP_XXX or
* \c MBEDTLS_MPI_XXX error code on failure.
*/
@ -210,8 +206,6 @@ int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
* 0: The key of the peer.
*
* \return \c 0 on success.
* \return #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
* operations was reached: see \c mbedtls_ecp_set_max_ops().
* \return Another \c MBEDTLS_ERR_ECP_XXX error code on failure.
*
*/

View File

@ -350,9 +350,19 @@ mbedtls_ecp_keypair;
* same; they must not be used until the function finally
* returns 0.
*
* This only affects functions that accept a pointer to a
* \c mbedtls_ecp_restart_ctx as an argument, and only works
* if that pointer is valid (in particular, not NULL).
* This only applies to functions whose documentation
* mentions they may return #MBEDTLS_ERR_ECP_IN_PROGRESS (or
* #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS for functions in the
* SSL module). For functions that accept a "restart context"
* argument, passing NULL disables restart and makes the
* function equivalent to the function with the same name
* with \c _restartable removed. For functions in the ECDH
* module, restart is disabled unless the function accepts
* an "ECDH context" argument and
* mbedtls_ecdh_enable_restart() was previously called on
* that context. For function in the SSL module, restart is
* only enabled for specific sides and key exchanges
* (currently only for clients and ECDHE-ECDSA).
*
* \param max_ops Maximum number of basic operations done in a row.
* Default: 0 (unlimited).

View File

@ -2914,15 +2914,41 @@ int mbedtls_ssl_get_session( const mbedtls_ssl_context *ssl, mbedtls_ssl_session
*
* \param ssl SSL context
*
* \return 0 if successful, or
* MBEDTLS_ERR_SSL_WANT_READ or MBEDTLS_ERR_SSL_WANT_WRITE, or
* MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED (see below), or
* a specific SSL error code.
* \return \c 0 if successful.
* \return #MBEDTLS_ERR_SSL_WANT_READ or #MBEDTLS_ERR_SSL_WANT_WRITE
* in the handshake is incomplete but or waiting for data to
* be availaible for reading from or writing to the underlying
* transport - in this case you must call this function again
* when the underlying transport is ready for the operation.
* \return #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS if an asynchronous
* operation is in progress (see
* mbedtls_ssl_conf_async_private_cb()) - in this case you
* must call this function again when the operation is ready.
* \return #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS if a cryptographic
* operation is in progress (see mbedtls_ecp_set_max_ops()) -
* in this case you must call this function again to complete
* the handshake when you're done attending other tasks.
* \return #MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED if DTLS is in use
* and the client did not demonstrate reachability yet - in
* this case you must stop using the context (see below).
* \return Another SSL error code - in this case you must stop using
* the context (see below).
*
* If this function returns MBEDTLS_ERR_SSL_WANT_READ, the
* handshake is unfinished and no further data is available
* from the underlying transport. In this case, you must call
* the function again at some later stage.
* \warning If this function returns something other than
* \c 0,
* #MBEDTLS_ERR_SSL_WANT_READ,
* #MBEDTLS_ERR_SSL_WANT_WRITE,
* #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS or
* #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS,
* you must stop using the SSL context for reading or writing,
* and either free it or call \c mbedtls_ssl_session_reset()
* on it before re-using it for a new connection; the current
* connection must be closed.
*
* \note If DTLS is in use, then you may choose to handle
* #MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED specially for logging
* purposes, as it is an expected return value rather than an
* actual error, but you still need to reset/free the context.
*
* \note Remarks regarding event-driven DTLS:
* If the function returns MBEDTLS_ERR_SSL_WANT_READ, no datagram
@ -2932,17 +2958,6 @@ int mbedtls_ssl_get_session( const mbedtls_ssl_context *ssl, mbedtls_ssl_session
* in which case the datagram of the underlying transport that is
* currently being processed might or might not contain further
* DTLS records.
*
* \note If this function returns something other than 0 or
* MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
* the SSL context for reading or writing, and either free it or
* call \c mbedtls_ssl_session_reset() on it before re-using it
* for a new connection; the current connection must be closed.
*
* \note If DTLS is in use, then you may choose to handle
* MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED specially for logging
* purposes, as it is an expected return value rather than an
* actual error, but you still need to reset/free the context.
*/
int mbedtls_ssl_handshake( mbedtls_ssl_context *ssl );
@ -2950,20 +2965,21 @@ int mbedtls_ssl_handshake( mbedtls_ssl_context *ssl );
* \brief Perform a single step of the SSL handshake
*
* \note The state of the context (ssl->state) will be at
* the next state after execution of this function. Do not
* the next state after this function returns \c 0. Do not
* call this function if state is MBEDTLS_SSL_HANDSHAKE_OVER.
*
* \note If this function returns something other than 0 or
* MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
* the SSL context for reading or writing, and either free it or
* call \c mbedtls_ssl_session_reset() on it before re-using it
* for a new connection; the current connection must be closed.
*
* \param ssl SSL context
*
* \return 0 if successful, or
* MBEDTLS_ERR_SSL_WANT_READ or MBEDTLS_ERR_SSL_WANT_WRITE, or
* a specific SSL error code.
* \return See mbedtls_ssl_handshake().
*
* \warning If this function returns something other than \c 0,
* #MBEDTLS_ERR_SSL_WANT_READ, #MBEDTLS_ERR_SSL_WANT_WRITE,
* #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS or
* #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS, you must stop using
* the SSL context for reading or writing, and either free it
* or call \c mbedtls_ssl_session_reset() on it before
* re-using it for a new connection; the current connection
* must be closed.
*/
int mbedtls_ssl_handshake_step( mbedtls_ssl_context *ssl );
@ -2978,13 +2994,18 @@ int mbedtls_ssl_handshake_step( mbedtls_ssl_context *ssl );
* \param ssl SSL context
*
* \return 0 if successful, or any mbedtls_ssl_handshake() return
* value.
* value except #MBEDTLS_ERR_SSL_CLIENT_RECONNECT that can't
* happen during a renegotiation.
*
* \warning If this function returns something other than \c 0,
* #MBEDTLS_ERR_SSL_WANT_READ, #MBEDTLS_ERR_SSL_WANT_WRITE,
* #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS or
* #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS, you must stop using
* the SSL context for reading or writing, and either free it
* or call \c mbedtls_ssl_session_reset() on it before
* re-using it for a new connection; the current connection
* must be closed.
*
* \note If this function returns something other than 0 or
* MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
* the SSL context for reading or writing, and either free it or
* call \c mbedtls_ssl_session_reset() on it before re-using it
* for a new connection; the current connection must be closed.
*/
int mbedtls_ssl_renegotiate( mbedtls_ssl_context *ssl );
#endif /* MBEDTLS_SSL_RENEGOTIATION */
@ -2996,40 +3017,54 @@ int mbedtls_ssl_renegotiate( mbedtls_ssl_context *ssl );
* \param buf buffer that will hold the data
* \param len maximum number of bytes to read
*
* \return One of the following:
* - 0 if the read end of the underlying transport was closed,
* - the (positive) number of bytes read, or
* - a negative error code on failure.
* \return The (positive) number of bytes read if successful.
* \return \c 0 is the read end of the underlying transport was closed
* - in this case you must stop using the context (see below).
* \return #MBEDTLS_ERR_SSL_WANT_READ or #MBEDTLS_ERR_SSL_WANT_WRITE
* in the handshake is incomplete but or waiting for data to
* be availaible for reading from or writing to the underlying
* transport - in this case you must call this function again
* when the underlying transport is ready for the operation.
* \return #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS if an asynchronous
* operation is in progress (see
* mbedtls_ssl_conf_async_private_cb()) - in this case you
* must call this function again when the operation is ready.
* \return #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS if a cryptographic
* operation is in progress (see mbedtls_ecp_set_max_ops()) -
* in this case you must call this function again to complete
* the handshake when you're done attending other tasks.
* \return #MBEDTLS_ERR_SSL_CLIENT_RECONNECT if we're at the server
* side of a DTLS connection and the client is initiating a
* new commection using the same source port. See below.
* \return Another SSL error code - in this case you must stop using
* the context (see below).
*
* If MBEDTLS_ERR_SSL_WANT_READ is returned, no application data
* is available from the underlying transport. In this case,
* the function needs to be called again at some later stage.
* \warning If this function returns something other than
* a positive value,
* #MBEDTLS_ERR_SSL_WANT_READ,
* #MBEDTLS_ERR_SSL_WANT_WRITE,
* #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS,
* #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS or
* #MBEDTLS_ERR_SSL_CLIENT_RECONNECT,
* you must stop using the SSL context for reading or writing,
* and either free it or call \c mbedtls_ssl_session_reset()
* on it before re-using it for a new connection; the current
* connection must be closed.
*
* If MBEDTLS_ERR_SSL_WANT_WRITE is returned, a write is pending
* but the underlying transport isn't available for writing. In this
* case, the function needs to be called again at some later stage.
*
* When this function return MBEDTLS_ERR_SSL_CLIENT_RECONNECT
* \note When this function return MBEDTLS_ERR_SSL_CLIENT_RECONNECT
* (which can only happen server-side), it means that a client
* is initiating a new connection using the same source port.
* You can either treat that as a connection close and wait
* for the client to resend a ClientHello, or directly
* continue with \c mbedtls_ssl_handshake() with the same
* context (as it has beeen reset internally). Either way, you
* should make sure this is seen by the application as a new
* context (as it has been reset internally). Either way, you
* must make sure this is seen by the application as a new
* connection: application state, if any, should be reset, and
* most importantly the identity of the client must be checked
* again. WARNING: not validating the identity of the client
* again, or not transmitting the new identity to the
* application layer, would allow authentication bypass!
*
* \note If this function returns something other than a positive value
* or MBEDTLS_ERR_SSL_WANT_READ/WRITE or MBEDTLS_ERR_SSL_CLIENT_RECONNECT,
* you must stop using the SSL context for reading or writing,
* and either free it or call \c mbedtls_ssl_session_reset() on it
* before re-using it for a new connection; the current connection
* must be closed.
*
* \note Remarks regarding event-driven DTLS:
* - If the function returns MBEDTLS_ERR_SSL_WANT_READ, no datagram
* from the underlying transport layer is currently being processed,
@ -3060,16 +3095,34 @@ int mbedtls_ssl_read( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
* \param buf buffer holding the data
* \param len how many bytes must be written
*
* \return the number of bytes actually written (may be less than len),
* or MBEDTLS_ERR_SSL_WANT_WRITE or MBEDTLS_ERR_SSL_WANT_READ,
* or another negative error code.
* \return The (non-negative) number of bytes actually written if
* successfull (may be less than \p len).
* \return #MBEDTLS_ERR_SSL_WANT_READ or #MBEDTLS_ERR_SSL_WANT_WRITE
* in the handshake is incomplete but or waiting for data to
* be availaible for reading from or writing to the underlying
* transport - in this case you must call this function again
* when the underlying transport is ready for the operation.
* \return #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS if an asynchronous
* operation is in progress (see
* mbedtls_ssl_conf_async_private_cb()) - in this case you
* must call this function again when the operation is ready.
* \return #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS if a cryptographic
* operation is in progress (see mbedtls_ecp_set_max_ops()) -
* in this case you must call this function again to complete
* the handshake when you're done attending other tasks.
* \return Another SSL error code - in this case you must stop using
* the context (see below).
*
* \note If this function returns something other than 0, a positive
* value or MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop
* using the SSL context for reading or writing, and either
* free it or call \c mbedtls_ssl_session_reset() on it before
* re-using it for a new connection; the current connection
* must be closed.
* \warning If this function returns something other than
* a non-negative value,
* #MBEDTLS_ERR_SSL_WANT_READ,
* #MBEDTLS_ERR_SSL_WANT_WRITE,
* #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS or
* #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS,
* you must stop using the SSL context for reading or writing,
* and either free it or call \c mbedtls_ssl_session_reset()
* on it before re-using it for a new connection; the current
* connection must be closed.
*
* \note When this function returns MBEDTLS_ERR_SSL_WANT_WRITE/READ,
* it must be called later with the *same* arguments,