Correct base64 input (excluding ignored characters such as spaces) consists
of exactly 4*k, 4*k-1 or 4*k-2 digits, followed by 0, 1 or 2 equal signs
respectively.
Previously, any number of trailing equal signs up to 2 was accepted, but if
there fewer than 4*k digits-or-equals, the last partial block was counted in
`*olen` in buffer-too-small mode, but was not output despite returning 0.
Now `mbedtls_base64_decode()` insists on correct padding. This is
backward-compatible since the only plausible useful inputs that used to be
accepted were inputs with 4*k-1 or 4*k-2 digits and no trailing equal signs,
and those led to invalid (truncated) output. Furthermore the function now
always reports the exact output size in buffer-too-small mode.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Add unit tests covering cases where the number of digits plus equal signs is
not a multiple of 4. These are invalid inputs, but they are currently
accepted as long as the number of equal signs is at most 2.
The tests assert the current behavior, not behavior that is desirable.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Reinforce the unit test for `mbedtls_base64_decode()` with valid inputs to
systematically call the function with a smaller output buffer and with an
empty output buffer. Assert the reported necessary output length in those
cases.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
digits is also a local variable in host_test.function, leading to compilers
complaining about that shadowing the global variable in
test_suite_base64.function.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This is part of the definition of the encoding, not a choice of test
parameter, so keep it with the test code.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Add unit tests for mask_of_range(), enc_char() and dec_value().
When constant-flow testing is enabled, verify that these functions are
constant-flow.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Marked dirty memory ends up in the result buffer after encoding (due to
the input having been marked dirty), and then the final comparison
to make sure that we got what we expected was triggering the constant
flow checker.
Signed-off-by: Paul Elliott <paul.elliott@arm.com>
Changes include:
- Integers marked with '#' in the .function files.
- Strings should have "" in .data files.
- String comparison instead of preprocessor-like replace for e.g. '=='
- Params and variables cannot have the same name in .function files
