The basis for the Lucky 13 family of attacks is for an attacker to be able to
distinguish between (long) valid TLS-CBC padding and invalid TLS-CBC padding.
Since our code sets padlen = 0 for invalid padding, the length of the input to
the HMAC function gives information about that.
Information about this length (modulo the MD/SHA block size) can be deduced
from how much MD/SHA padding (this is distinct from TLS-CBC padding) is used.
If MD/SHA padding is read from a (static) buffer, a local attacker could get
information about how much is used via a cache attack targeting that buffer.
Let's get rid of this buffer. Now the only buffer used is the internal MD/SHA
one, which is always read fully by the process() function.
* mbedtls-1.3:
Use link-time garbage collection in memory.sh
scripts/memory.sh only work on Linux
Add missing 'const' on selftest data
Use only headers for doxygen (no doc in C files)
Add missing extern "C" guard in aesni.h
Fix compile error with renego disabled
Remove slow PKCS5 test
Stop checking key-cert match systematically
Make tests/*.sh runnable from anywhere
Update visual C files
All symmetric cipher algorithms and hash algorithms now include support
for a POLARSSL_XXX_ALT flag that prevents the definition of the
algorithm context structure and all 'core' functions.
(cherry picked from commit 4087c47043)
New padding checking is unbiased on correct or incorrect padding and
has no branch prediction timing differences.
The additional MAC checks further straighten out the timing differences.
- As a consequence all error code that were positive were changed. A lot of MALLOC_FAILED and FILE_IO_ERROR error codes added for different modules.
- Programs and tests were adapted accordingly
