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`.
The function ecp_gen_keypair_base did not wipe the stack buffer used to
hold the private exponent before returning. This commit fixes this by not using
a stack buffer in the first place but instead calling mpi_fill_random directly
to acquire the necessary random MPI.
This commit modifies mpi_read_binary to always allocate the minimum number of
limbs required to hold the entire buffer provided to the function, regardless of
its content. Previously, leading zero bytes in the input data were detected and
used to reduce memory footprint and time, but this non-constant behavior turned
out to be non-tolerable for the cryptographic applications this function is used
for.
Previously, if `POLARSSL_SSL_RENEGOTIATION` was disabled, incoming handshake
messages in `ssl_read` (expecting application data) lead to the connection being
closed. This commit fixes this, restricting the
`POLARSSL_SSL_RENEGOTIATION`-guard to the code-paths responsible for accepting
renegotiation requests and aborting renegotiation attempts after too many
unexpected records have been received.
This commit fixes a comparison of ssl_session->encrypt_then_mac against the
ETM-unrelated constant SSL_EXTENDED_MS_DISABLED. Instead, SSL_ETM_DISABLED
should be used.
The typo is has no functional effect since both constants have the same value 0.
Remove a check introduced in the previous buffer overflow fix with keys of
size 8N+1 which the subsequent fix for buffer start calculations made
redundant.
Added a changelog entry for the buffer start calculation fix.
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.
Signature algorithm extension was skipped when renegotiation was in
progress, causing the signature algorithm not to be known when
renegotiating, and failing the handshake. Fix removes the renegotiation
step check before parsing the extension.
The warning was caused because in MSVC some of the function parameters
for the socket APIs are int while the fields in struct addrinfo are
size_t e.g. possible data loss.
The warning was caused because of conversions from size_t to int, which
can cause data loss. The files affected are:
* ssl_client2.c
* ssl_server2.c
* ssl_mail_client.c
This commit adds the following command line options to programs/x509/cert_write:
- version (val 1, 2, 3): Set the certificate's version (v1, v2, v3)
- authority_identifier (val 0, 1): Enable or disable the addition of the
authority identifier extension.
- subject_identifier (val 0, 1): Enable or disable the addition of the
subject identifier extension.
- basic_constraints (val 0, 1): Enable or disable the addition of the
basic constraints extension.
- md (val MD5, SHA1, SHA256, SHA512): Set the hash function used
when creating the CRT.
This commit removes extension-writing code for X.509 non-v3 certificates from
x509write_crt_der. Previously, even if no extensions were present an
empty sequence would have been added.
(1) Add missing error condition
(2) Specify allowance and effect of of NULL hostname parameter
(3) Describe effect of function on failure
Also, adapt ChangeLog.
