Initial implementation for the AEAD APIs, missing the following:
* Concatenation of the tag to the output buffer.
* Updated documentation of the new functions.
* argument validations
* tests
Conflicts:
library/psa_crypto.c
tests/suites/test_suite_psa_crypto.data
tests/suites/test_suite_psa_crypto.function
All the conflicts are concurrent additions where the order doesn't
matter. I put the code from feature-psa (key policy) before the code
from PR #13 (key lifetime).
psa_get_key_lifetime() behavior changed regarding empty slots, now
it return the lifetime of and empty slots. Documentation in header
file updated accordingly.
Conflict resolution:
* `tests/suites/test_suite_psa_crypto.data`: in the new tests from PR #14,
rename `PSA_ALG_RSA_PKCS1V15_RAW` to `PSA_ALG_RSA_PKCS1V15_SIGN_RAW` as
was done in PR #15 in the other branch.
New header file crypto_struct.h. The main file crypto.sh declares
structures which are implementation-defined. These structures must be
defined in crypto_struct.h, which is included at the end so that the
structures can use types defined in crypto.h.
Implement psa_hash_start, psa_hash_update and psa_hash_final. This
should work for all hash algorithms supported by Mbed TLS, but has
only been smoke-tested for SHA-256, and only in the nominal case.
Don't use the pk module except as required for pkparse/pkwrite. The
PSA crypto layer is meant to work alongside pk, not on top of it.
Fix the compile-time dependencies on RSA/ECP handling in
psa_export_key, psa_destroy_key and psa_get_key_information.
Define psa_key_type_t and a first stab at a few values.
New functions psa_import_key, psa_export_key, psa_destroy_key,
psa_get_key_information. Implement them for raw data and RSA.
Under the hood, create an in-memory, fixed-size keystore with room
for MBEDTLS_PSA_KEY_SLOT_COUNT - 1 keys.
Add a new function mbedtls_rsa_get_bitlen which returns the RSA key
size, i.e. the bit size of the modulus. In the pk module, call
mbedtls_rsa_get_bitlen instead of mbedtls_rsa_get_len, which gave the
wrong result for key sizes that are not a multiple of 8.
This commit adds one non-regression test in the pk suite. More tests
are needed for RSA key sizes that are a multiple of 8.
This commit does not address RSA alternative implementations, which
only provide an interface that return the modulus size in bytes.
New module psa_crypto.c (MBEDTLS_PSA_CRYPTO_C):
Platform Security Architecture compatibility layer on top of
libmedcrypto.
Implement psa_crypto_init function which sets up a RNG.
Add a mbedtls_psa_crypto_free function which deinitializes the
library.
Define a first batch of error codes.
By the standard (RFC 6066, Sect. 4), the Maximum Fragment Length (MFL)
extension limits the maximum record payload size, but not the maximum
datagram size. However, not inferring any limitations on the MTU when
setting the MFL means that a party has no means to dynamically inform
the peer about MTU limitations.
This commit changes the function ssl_get_remaining_payload_in_datagram()
to never return more than
MFL - { Total size of all records within the current datagram }
thereby limiting the MTU to MFL + { Maximum Record Expansion }.
The function ssl_free_buffered_record() frees a future epoch record, if
such is present. Previously, it was called in mbedtls_handshake_free(),
i.e. an unused buffered record would be cleared at the end of the handshake.
This commit moves the call to the function ssl_buffering_free() responsible
for freeing all buffering-related data, and which is called not only at
the end of the handshake, but at the end of every flight. In particular,
future record epochs won't be buffered across flight boundaries anymore,
and they shouldn't.
The previous code appended messages to flights only if their handshake type,
as derived from the first byte in the message, was different from
MBEDTLS_SSL_HS_HELLO_REQUEST. This check should only be performed
for handshake records, while CCS records should immediately be appended.
In SSLv3, the client sends a NoCertificate alert in response to
a CertificateRequest if it doesn't have a CRT. This previously
lead to failure in ssl_write_handshake_msg() which only accepted
handshake or CCS records.
The previous code appended messages to flights only if their handshake type,
as derived from the first byte in the message, was different from
MBEDTLS_SSL_HS_HELLO_REQUEST. This check should only be performed
for handshake records, while CCS records should immediately be appended.
In SSLv3, the client sends a NoCertificate alert in response to
a CertificateRequest if it doesn't have a CRT. This previously
lead to failure in ssl_write_handshake_msg() which only accepted
handshake or CCS records.
Previous commits introduced the field `total_bytes_buffered`
which is supposed to keep track of the cumulative size of
all heap allocated buffers used for the purpose of reassembly
and/or buffering of future messages.
However, the buffering of future epoch records were not reflected
in this field so far. This commit changes this, adding the length
of a future epoch record to `total_bytes_buffered` when it's buffered,
and subtracting it when it's freed.
This commit adds a static function ssl_buffer_make_space() which
takes a buffer size as an argument and attempts to free as many
future message bufffers as necessary to ensure that the desired
amount of buffering space is available without violating the
total buffering limit set by MBEDTLS_SSL_DTLS_MAX_BUFFERING.
If the next expected handshake message can't be reassembled because
buffered future messages have already used up too much of the available
space for buffering, free those future message buffers in order to
make space for the reassembly, starting with the handshake message
that's farthest in the future.
This commit adds a static function ssl_buffering_free_slot()
which allows to free a particular structure used to buffer
and/or reassembly some handshake message.
This commit introduces a compile time constant MBEDTLS_SSL_DTLS_MAX_BUFFERING
to mbedtls/config.h which allows the user to control the cumulative size of
all heap buffer allocated for the purpose of reassembling and buffering
handshake messages.
It is put to use by introducing a new field `total_bytes_buffered` to
the buffering substructure of `mbedtls_ssl_handshake_params` that keeps
track of the total size of heap allocated buffers for the purpose of
reassembly and buffering at any time. It is increased whenever a handshake
message is buffered or prepared for reassembly, and decreased when a
buffered or fully reassembled message is copied into the input buffer
and passed to the handshake logic layer.
This commit does not yet include future epoch record buffering into
account; this will be done in a subsequent commit.
Also, it is now conceivable that the reassembly of the next expected
handshake message fails because too much buffering space has already
been used up for future messages. This case currently leads to an
error, but instead, the stack should get rid of buffered messages
to be able to buffer the next one. This will need to be implemented
in one of the next commits.
A previous commit introduced the function ssl_prepare_reassembly_buffer()
which took a message length and a boolean flag indicating if a reassembly
bit map was needed, and attempted to heap-allocate a buffer of sufficient
size to hold both the message, its header, and potentially the reassembly
bitmap.
A subsequent commit is going to introduce a limit on the amount of heap
allocations allowed for the purpose of buffering, and this change will
need to know the reassembly buffer size before attempting the allocation.
To this end, this commit changes ssl_prepare_reassembly_buffer() into
ssl_get_reassembly_buffer_size() which solely computes the reassembly
buffer size, and performing the heap allocation manually in
ssl_buffer_message().
This commit moves the length and content check for CCS messages to
the function mbedtls_ssl_handle_message_type() which is called after
a record has been deprotected.
Previously, these checks were performed in the function
mbedtls_ssl_parse_change_cipher_spec(); however, now that
the arrival of out-of-order CCS messages is remembered
as a boolean flag, the check also has to happen when this
flag is set. Moving the length and content check to
mbedtls_ssl_handle_message_type() allows to treat both
checks uniformly.
Depends on the current transform, which might change when retransmitting a
flight containing a Finished message, so compute it only after the transform
is swapped.
