Previously, MAC validation for an incoming record proceeded as follows:
1) Make a copy of the MAC contained in the record;
2) Compute the expected MAC in place, overwriting the presented one;
3) Compare both.
This resulted in a record buffer overflow if truncated MAC was used, as in this
case the record buffer only reserved 10 bytes for the MAC, but the MAC
computation routine in 2) always wrote a full digest.
For specially crafted records, this could be used to perform a controlled write of
up to 6 bytes past the boundary of the heap buffer holding the record, thereby
corrupting the heap structures and potentially leading to a crash or remote code
execution.
This commit fixes this by making the following change:
1) Compute the expected MAC in a temporary buffer that has the size of the
underlying message digest.
2) Compare to this to the MAC contained in the record, potentially
restricting to the first 10 bytes if truncated HMAC is used.
A similar fix is applied to the encryption routine `ssl_encrypt_buf`.
For a key of size 8N+1, check that the first byte after applying the
public key operation is 0 (it could have been 1 instead). The code was
incorrectly doing a no-op check instead, which led to invalid
signatures being accepted. Not a security flaw, since you would need the
private key to craft such an invalid signature, but a bug nonetheless.
The check introduced by the previous security fix was off by one. It
fixed the buffer overflow but was not compliant with the definition of
PSS which technically led to accepting some invalid signatures (but
not signatures made without the private key).
Fix buffer overflow in RSA-PSS signature verification when the hash is
too large for the key size. Found by Seth Terashima, Qualcomm.
Added a non-regression test and a positive test with the smallest
permitted key size for a SHA-512 hash.
This commit adds regression tests for the bug when we didn't parse the
Signature Algorithm extension when renegotiating. (By nature, this bug
affected only the server)
The tests check for the fallback hash (SHA1) in the server log to detect
that the Signature Algorithm extension hasn't been parsed at least in
one of the handshakes.
A more direct way of testing is not possible with the current test
framework, since the Signature Algorithm extension is parsed in the
first handshake and any corresponding debug message is present in the
logs.
The test case parses an RSA private key with N=P=Q=D=E=1 and expects a failure from the PK layer. With the weakened
semantics of `mbedtls_rsa_complete`, the latter won't throw an error on that key in case if MBEDTLS_RSA_NO_CRT is
set. This commit modifies the test case to use N=2 which is rejected by `mbedtls_rsa_complete` regardless of whether
MBEDTLS_RSA_NO_CRT is set or not.
The number of loop iterations per candidate in `mbedtls_deduce_primes` was off
by one. This commit corrects this and removes a toy non-example from the RSA
test suite, as it seems difficult to have the function fail on small values of N
even if D,E are corrupted.
This commit adds regression tests for the bug when we didn't parse the
Signature Algorithm extension when renegotiating. (By nature, this bug
affected only the server)
The tests check for the fallback hash (SHA1) in the server log to detect
that the Signature Algorithm extension hasn't been parsed at least in
one of the handshakes.
A more direct way of testing is not possible with the current test
framework, since the Signature Algorithm extension is parsed in the
first handshake and any corresponding debug message is present in the
logs.
This commit splits off the RSA helper functions into separate headers and
compilation units to have a clearer separation of the public RSA interface,
intended to be used by end-users, and the helper functions which are publicly
provided only for the benefit of designers of alternative RSA implementations.
The tests now accept two result parameters, one for the expected result of the
completion call, and one for the expected result of the subsequent sanity
check.
The change modifies the template code in tests/suites/helpers.function
and tests/suites/main.function so that error messages are printed to
stdout instead of being discarded. This makes errors visible regardless
of the --verbose flag being passed or not to the test suite programs.
The change modifies the template code in tests/suites/helpers.function
and tests/suites/main.function so that error messages are printed to
stdout instead of being discarded. This makes errors visible regardless
of the --verbose flag being passed or not to the test suite programs.
Add a test to ssl-opt.sh that parses the client and server debug
output and then checks that the Unix timestamp in the ServerHello
message is within acceptable bounds.
Extend the run_test function in ssl-opt.sh so that it accepts the -f
and -F options. These parameters take an argument which is the name of
a shell function that will be called by run_test and will be given the
client input and output debug log. The idea is that these functions are
defined by each test and they can be used to do some custom check
beyon those allowed by the pattern matching capabilities of the
run_test function.
Add a test case calling ssl_set_hostname twice to test_suite_ssl.
When run in CMake build mode ASan, this catches the current leak,
but will hopefully be fine with the new version.
Add a test to ssl-opt.sh that parses the client and server debug
output and then checks that the Unix timestamp in the ServerHello
message is within acceptable bounds.
Extend the run_test function in ssl-opt.sh so that it accepts the -f
and -F options. These parameters take an argument which is the name of
a shell function that will be called by run_test and will be given the
client input and output debug log. The idea is that these functions are
defined by each test and they can be used to do some custom check
beyon those allowed by the pattern matching capabilities of the
run_test function.
As the new PKCS v1.5 verification function opaquely compares an expected encoding to the given one, it cannot
distinguish multiple reasons of failure anymore and instead always returns MBEDTLS_ERR_RSA_VERIFY_FAILED. This
necessitates some modifications to the expected return values of some tests verifying signatures with bad padding.
This commit adds some tests to the RSA test suite verifying that RSA PKCS-v15 signatures with non-reduced length
encodings are refuted. Details are provided via comments in the test suite data file.
