The macro constant `MBEDTLS_SSL_MAC_ADD` defined in `ssl_internal.h`
defines an upper bound for the amount of space needed for the record
authentication tag. Its definition distinguishes between the
presence of an ARC4 or CBC ciphersuite suite, in which case the maximum
size of an enabled SHA digest is used; otherwise, `MBEDTLS_SSL_MAC_ADD`
is set to 16 to accomodate AEAD authentication tags.
This assignment has a flaw in the situation where confidentiality is
not needed and the NULL cipher is in use. In this case, the
authentication tag also uses a SHA digest, but the definition of
`MBEDTLS_SSL_MAC_ADD` doesn't guarantee enough space.
The present commit fixes this by distinguishing between the presence
of *some* ciphersuite using a MAC, including those using a NULL cipher.
For that, the previously internal macro `SSL_SOME_MODES_USE_MAC` from
`ssl_tls.c` is renamed and moved to the public macro
`MBEDTLS_SOME_MODES_USE_MAC` defined in `ssl_internal.h`.
Prior to this commit, the security parameter struct `ssl_transform`
contained a `ciphersuite_info` field pointing to the information
structure for the negotiated ciphersuite. However, the only
information extracted from that structure that was used in the core
encryption and decryption functions `ssl_encrypt_buf`/`ssl_decrypt_buf`
was the authentication tag length in case of an AEAD cipher.
The present commit removes the `ciphersuite_info` field from the
`ssl_transform` structure and adds an explicit `taglen` field
for AEAD authentication tag length.
This is in accordance with the principle that the `ssl_transform`
structure should contain the raw parameters needed for the record
encryption and decryption functions to work, but not the higher-level
information that gave rise to them. For example, the `ssl_transform`
structure implicitly contains the encryption/decryption keys within
their cipher contexts, but it doesn't contain the SSL master or
premaster secrets. Likewise, it contains an explicit `maclen`, while
the status of the 'Truncated HMAC' extension -- which determines the
value of `maclen` when the `ssl_transform` structure is created in
`ssl_derive_keys` -- is not contained in `ssl_transform`.
The `ciphersuite_info` pointer was used in other places outside
the encryption/decryption functions during the handshake, and for
these functions to work, this commit adds a `ciphersuite_info` pointer
field to the handshake-local `ssl_handshake_params` structure.
The `ssl_transform` security parameter structure contains opaque
cipher contexts for use by the record encryption/decryption functions
`ssl_decrypt_buf`/`ssl_encrypt_buf`, while the underlying key material
is configured once in `ssl_derive_keys` and is not explicitly dealt with
anymore afterwards. In particular, the key length is not needed
explicitly by the encryption/decryption functions but is nonetheless
stored in an explicit yet superfluous `keylen` field in `ssl_transform`.
This commit removes this field.
* public/mbedtls-2.16: (40 commits)
Clarify comment mangled by an earlier refactoring
Add an "out-of-box" component
Run ssl-opt.sh on 32-bit runtime
Fix typo in data_file generator code
Give credit to OSS-Fuzz for #2404
Remove ssl_cert_test sample app
Fix the proxy seed in Travis runs
Update library version to 2.16.1
Fix errors in AEAD test function
x509.c: Fix potential memory leak in X.509 self test
Remove Circle CI script
Fix ChangeLog entry ordering
Fix typo
Add non-regression test for buffer overflow
Improve documentation of mbedtls_mpi_write_string()
Adapt ChangeLog
Fix 1-byte buffer overflow in mbedtls_mpi_write_string()
Change Perl to Python in test builds
Fix default port number information
Silence pylint
...
* origin/pr/2545: (24 commits)
Use check_output instead of Popen
Start unused variable with underscore
Correct documentation
Check that the report directory is a directory
Use namespaces instead of full classes
Fix pylint issues
Don't put abi dumps in subfolders
Add verbose switch to silence all output except the final report
Fetch the remote crypto branch, rather than cloning it
Prefix internal functions with underscore
Add RepoVersion class to make handling of many arguments easier
Reduce indentation levels
Improve documentation
Use optional arguments for setting repositories
Only build the library
Add ability to compare submodules from different repositories
Add handling for cases when not all .so files are present
Extend functionality to allow setting crypto submodule version
Simplify logic for checking if report folder can be removed
Add option for a brief report of problems only
...
This commit improves hygiene and formatting of macro definitions
throughout the library. Specifically:
- It adds brackets around parameters to avoid unintended
interpretation of arguments, e.g. due to operator precedence.
- It adds uses of the `do { ... } while( 0 )` idiom for macros that
can be used as commands.
requires_config_enabled doesn't support multiple config options.
Tests having multiple configuration dependencies must be prefixed
with multiple invocations of requires_config_enabled instead.
When doing ABI/API checking, its useful to have a list of all the
identifiers that are defined in the internal header files, as we
do not promise compatibility for them. This option allows for a
simple method of getting them for use with the ABI checking script.
There are a number of arguments being passed around, nearly all of
which are duplicated between the old and new versions. Moving these
into a separate class should hopefully make it simpler to follow
what is being done.
