* origin/mbedtls-2.16:
Fix some pylint warnings
Enable more test cases without MBEDTLS_MEMORY_DEBUG
More accurate test case description
Clarify that the "FATAL" message is expected
Note that mbedtls_ctr_drbg_seed() must not be called twice
Fix CTR_DRBG benchmark
Changelog entry for xxx_drbg_set_entropy_len before xxx_drbg_seed
CTR_DRBG: support set_entropy_len() before seed()
CTR_DRBG: Don't use functions before they're defined
HMAC_DRBG: support set_entropy_len() before seed()
The functions mbedtls_ctr_drbg_random() and
mbedtls_ctr_drbg_random_with_add() could return 0 if an AES function
failed. This could only happen with alternative AES
implementations (the built-in implementation of the AES functions
involved never fail), typically due to a failure in a hardware
accelerator.
Bug reported and fix proposed by Johan Uppman Bruce and Christoffer
Lauri, Sectra.
None of the test cases in tests_suite_memory_buffer_alloc actually
need MBEDTLS_MEMORY_DEBUG. Some have additional checks when
MBEDTLS_MEMORY_DEBUG but all are useful even without it. So enable
them all and #ifdef out the parts that require DEBUG.
The test case "Memory buffer small buffer" emits a message
"FATAL: verification of first header failed". In this test case, it's
actually expected, but it looks weird to see this message from a
passing test. Add a comment that states this explicitly, and modify
the test description to indicate that the failure is expected, and
change the test function name to be more accurate.
Fix#309
In ssl_parse_hello_verify_request, we read 3 bytes (version and cookie
length) without checking that there are that many bytes left in
ssl->in_msg. This could potentially read from memory outside of the
ssl->receive buffer (which would be a remotely exploitable
crash).
In ssl_parse_hello_verify_request, we print cookie_len bytes without
checking that there are that many bytes left in ssl->in_msg. This
could potentially log data outside the received message (not a big
deal) and could potentially read from memory outside of the receive
buffer (which would be a remotely exploitable crash).
* restricted/pr/667: (24 commits)
Add ChangeLog entry
mpi_lt_mpi_ct: fix condition handling
mpi_lt_mpi_ct: Add further tests
mpi_lt_mpi_ct: Fix test numbering
mpi_lt_mpi_ct perform tests for both limb size
ct_lt_mpi_uint: cast the return value explicitely
mbedtls_mpi_lt_mpi_ct: add tests for 32 bit limbs
mbedtls_mpi_lt_mpi_ct: simplify condition
Rename variable for better readability
mbedtls_mpi_lt_mpi_ct: Improve documentation
Make mbedtls_mpi_lt_mpi_ct more portable
Bignum: Document assumptions about the sign field
Add more tests for mbedtls_mpi_lt_mpi_ct
mpi_lt_mpi_ct test: hardcode base 16
Document ct_lt_mpi_uint
mpi_lt_mpi_ct: make use of unsigned consistent
ct_lt_mpi_uint: make use of biL
Change mbedtls_mpi_cmp_mpi_ct to check less than
mbedtls_mpi_cmp_mpi_ct: remove multiplications
Remove excess vertical space
...
This issue has been reported by Tuba Yavuz, Farhaan Fowze, Ken (Yihang) Bai,
Grant Hernandez, and Kevin Butler (University of Florida) and
Dave Tian (Purdue University).
In AES encrypt and decrypt some variables were left on the stack. The value
of these variables can be used to recover the last round key. To follow best
practice and to limit the impact of buffer overread vulnerabilities (like
Heartbleed) we need to zeroize them before exiting the function.
The corner case tests were designed for 32 and 64 bit limbs
independently and performed only on the target platform. On the other
platform they are not corner cases anymore, but we can still exercise
them.
The corner case tests were designed for 64 bit limbs and failed on 32
bit platforms because the numbers in the test ended up being stored in a
different number of limbs and the function (correctly) returnd an error
upon receiving them.
In the case of *ret we might need to preserve a 0 value throughout the
loop and therefore we need an extra condition to protect it from being
overwritten.
The value of done is always 1 after *ret has been set and does not need
to be protected from overwriting. Therefore in this case the extra
condition can be removed.
The code relied on the assumptions that CHAR_BIT is 8 and that unsigned
does not have padding bits.
In the Bignum module we already assume that the sign of an MPI is either
-1 or 1. Using this, we eliminate the above mentioned dependency.
The signature of mbedtls_mpi_cmp_mpi_ct() meant to support using it in
place of mbedtls_mpi_cmp_mpi(). This meant full comparison functionality
and a signed result.
To make the function more universal and friendly to constant time
coding, we change the result type to unsigned. Theoretically, we could
encode the comparison result in an unsigned value, but it would be less
intuitive.
Therefore we won't be able to represent the result as unsigned anymore
and the functionality will be constrained to checking if the first
operand is less than the second. This is sufficient to support the
current use case and to check any relationship between MPIs.
The only drawback is that we need to call the function twice when
checking for equality, but this can be optimised later if an when it is
needed.
Multiplication is known to have measurable timing variations based on
the operands. For example it typically is much faster if one of the
operands is zero. Remove them from constant time code.
