In DTLS, if mbedtls_ssl_fetch_input() is called multiple times without
resetting the input buffer in between, the non-initial calls are functionally
equivalent to mere bounds checks ensuring that the incoming datagram is
large enough to hold the requested data. In the interest of code-size
and modularity (removing a call to a non-const function which is logically
const in this instance), this commit replaces such a call to
mbedtls_ssl_fetch_input() by an explicit bounds check in
ssl_parse_record_header().
Previously, `ssl_handle_possible_reconnect()` was part of
`ssl_parse_record_header()`, which was required to return a non-zero error
code to indicate a record which should not be further processed because it
was invalid, unexpected, duplicate, .... In this case, some error codes
would lead to some actions to be taken, e.g. `MBEDTLS_ERR_SSL_EARLY_MESSAGE`
to potential buffering of the record, but eventually, the record would be
dropped regardless of the precise value of the error code. The error code
`MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED` returned from
`ssl_handle_possible_reconnect()` did not receive any special treatment and
lead to silent dopping of the record - in particular, it was never returned
to the user.
In the new logic this commit introduces, `ssl_handle_possible_reconnect()` is
part of `ssl_check_client_reconnect()` which is triggered _after_
`ssl_parse_record_header()` found an unexpected record, which is already in
the code-path eventually dropping the record; we want to leave this code-path
only if a valid cookie has been found and we want to reset, but do nothing
otherwise. That's why `ssl_handle_possible_reconnect()` now returns `0` unless
a valid cookie has been found or a fatal error occurred.
Availability of sufficient incoming data should be checked when
it is needed, which is in mbedtls_ssl_fetch_input(), and this
function has the necessary bounds checks in place.
The check is in terms of the internal input buffer length and is
hence likely to be originally intended to protect against overflow
of the input buffer when fetching data from the underlying
transport in mbedtls_ssl_fetch_input(). For locality of reasoning,
it's better to perform such a check close to where it's needed,
and in fact, mbedtls_ssl_fetch_input() _does_ contain an equivalent
bounds check, too, rendering the bounds check in question redundant.
mbedtls_ssl_decrypt_buf() asserts that the passed transform is not NULL,
but the function is only invoked in a single place, and this invocation
is clearly visible to be within a branch ensuring that the incoming
transform isn't NULL. Remove the assertion for the benefit of code-size.
The previous code performed architectural maximum record length checks
both before and after record decryption. Since MBEDTLS_SSL_IN_CONTENT_LEN
bounds the maximum length of the record plaintext, it suffices to check
only once after (potential) decryption.
This must not be confused with the internal check that the record
length is small enough to make the record fit into the internal input
buffer; this is done in mbedtls_ssl_fetch_input().
Due to how the checking script is run in docker, worktree_rev is
ambiguous when running rev-parse. We're running it in the checked
out worktree, so we can use HEAD instead, which is unambiguous.
* origin/pr/2660:
Fix parsing issue when int parameter is in base 16
Refactor receive_uint32()
Refactor get_byte function
Make the script portable to both pythons
Update the test encoding to support python3
update the test script
* origin/pr/1622: (29 commits)
Do not build fuzz on windows
No booleans and import config
Removing space before opening parenthesis
Style corrections
Syntax fix
Fixes warnings from MSVC
Add a linker flag to enable gcov in basic-build-test.sh
checks MBEDTLS_PEM_PARSE_C
Restore programs/fuzz/Makefile after in-tree cmake
Move fuzz directory to programs
Documentation for corpus generation
Restore tests/fuzz/Makefile after in-tree cmake
Adding ifdefs to avoid warnings for unused globals
Adds LDFLAGS fsanitize=address
Ignore compiled object files and executables
Also clean the fuzz subdirectory
copyediting README.md
Protecting client/server fuzz targts with ifdefs
Makefile support 1
Fuzz README and direct compilation
...
* origin/pr/2729:
Split _abi_compliance_command into smaller functions
Record the commits that were compared
Document how to build the typical argument for -s
Allow running /somewhere/else/path/to/abi_check.py
* origin/pr/2706:
Update Mbed Crypto to contain mbed-crypto#152
CMake: Add a subdirectory build regression test
README: Enable builds as a CMake subproject
ChangeLog: Enable builds as a CMake subproject
Remove use of CMAKE_SOURCE_DIR
* origin/pr/2632:
Adapt ChangeLog
Avoid use of large stack buffers in mbedtls_x509_write_crt_pem()
Improve documentation of mbedtls_pem_write_buffer()
Perform CRT writing in-place on the output buffer
Adapt x509write_crt.c to coding style
* origin/pr/2455:
change .gitignore line endings to UNIX
Update ChangeLog
mention .gitignore changes in ChangeLog
add Visual Studio filters to .gitignore
update .gitignore to include Visual Studio artifacts
