The code paths in the library are different for decryption and for
signature. Improve the test coverage by doing some error path tests
for decryption in addition to signature.
The certificate passed to async callbacks may not be the one set by
mbedtls_ssl_conf_own_cert. For example, when using an SNI callback,
it's whatever the callback is using. Document this, and add a test
case (and code sample) with SNI.
Add a test case for SSL asynchronous signature where f_async_resume is
called twice. Verify that f_async_sign_start is only called once.
This serves as a non-regression test for a bug where f_async_sign_start
was only called once, which turned out to be due to a stale build
artifacts with mismatched numerical values of
MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS.
Testing the case where the resume callback returns an error at the
beginning and the case where it returns an error at the end is
redundant. Keep the test after the output has been produced, to
validate that the product does not use even a valid output if the
return value is an error code.
Document how the SSL async sign callback must treat its md_alg and
hash parameters when doing an RSA signature: sign-the-hash if md_alg
is nonzero (TLS 1.2), and sign-the-digestinfo if md_alg is zero
(TLS <= 1.1).
In ssl_server2, don't use md_alg=MBEDTLS_MD_NONE to indicate that
ssl_async_resume must perform an encryption, because md_alg is also
MBEDTLS_MD_NONE in TLS <= 1.1. Add a test case to exercise this
case (signature with MBEDTLS_MD_NONE).
Conflict resolution:
* ChangeLog: put the new entry from my branch in the proper place.
* include/mbedtls/error.h: counted high-level module error codes again.
* include/mbedtls/ssl.h: picked different numeric codes for the
concurrently added errors; made the new error a full sentence per
current standards.
* library/error.c: ran scripts/generate_errors.pl.
* library/ssl_srv.c:
* ssl_prepare_server_key_exchange "DHE key exchanges": the conflict
was due to style corrections in development
(4cb1f4d49c) which I merged with
my refactoring.
* ssl_prepare_server_key_exchange "For key exchanges involving the
server signing", first case, variable declarations: merged line
by line:
* dig_signed_len: added in async
* signature_len: removed in async
* hashlen: type changed to size_t in development
* hash: size changed to MBEDTLS_MD_MAX_SIZE in async
* ret: added in async
* ssl_prepare_server_key_exchange "For key exchanges involving the
server signing", first cae comment: the conflict was due to style
corrections in development (4cb1f4d49c)
which I merged with my comment changes made as part of refactoring
the function.
* ssl_prepare_server_key_exchange "Compute the hash to be signed" if
`md_alg != MBEDTLS_MD_NONE`: conflict between
ebd652fe2d
"ssl_write_server_key_exchange: calculate hashlen explicitly" and
46f5a3e9b4 "Check return codes from
MD in ssl code". I took the code from commit
ca1d742904 made on top of development
which makes mbedtls_ssl_get_key_exchange_md_ssl_tls return the
hash length.
* programs/ssl/ssl_server2.c: multiple conflicts between the introduction
of MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS and new auxiliary functions and
definitions for async support, and the introduction of idle().
* definitions before main: concurrent additions, kept both.
* main, just after `handshake:`: in the loop around
mbedtls_ssl_handshake(), merge the addition of support for
MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS and SSL_ASYNC_INJECT_ERROR_CANCEL
with the addition of the idle() call.
* main, if `opt.transport == MBEDTLS_SSL_TRANSPORT_STREAM`: take the
code from development and add a check for
MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS.
* main, loop around mbedtls_ssl_read() in the datagram case:
take the code from development and add a check for
MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS; revert to a do...while loop.
* main, loop around mbedtls_ssl_write() in the datagram case:
take the code from development and add a check for
MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS; revert to a do...while loop.
Add test cases for SSL asynchronous signature to ssl-opt.sh:
* Delay=0,1 to test the sequences of calls to f_async_resume
* Test fallback when the async callbacks don't support that key
* Test error injection at each stage
* Test renegotiation
Previously, the idling loop in ssl_server2 didn't check whether
the underlying call to mbedtls_net_poll signalled that the socket
became invalid. This had the consequence that during idling, the
server couldn't be terminated through a SIGTERM, as the corresponding
handler would only close the sockets and expect the remainder of
the program to shutdown gracefully as a consequence of this.
This was subsequently attempted to be fixed through a change
in ssl-opt.sh by terminating the server through a KILL signal,
which however lead to other problems when the latter was run
under valgrind.
This commit changes the idling loop in ssl_server2 and ssl_client2
to obey the return code of mbedtls_net_poll and gracefully shutdown
if an error occurs, e.g. because the socket was closed.
As a consequence, the server termination via a KILL signal in
ssl-opt.sh is no longer necessary, with the previous `kill; wait`
pattern being sufficient. The commit reverts the corresponding
change.
The UDP tests involving the merging of multiple records into single
datagrams accumulate records for 10ms, which can be less than the
total flight preparation time if e.g. the tests are being run with
valgrind.
This commit increases the packing time for the relevant tests
from 10ms to 50ms.
If lsof is not available, wait_server_start uses a fixed timeout,
which can trigger a race condition if the timeout turns out to be too
short. Emit a warning so that we know this is going on from the test
logs.
- Some of the CI machines don't have lsof installed yet, so rely on an sleeping
an arbitrary number of seconds while the server starts. We're seeing
occasional failures with the current delay because the CI machines are highly
loaded, which seems to indicate the current delay is not quite enough, but
hopefully not to far either, so double it.
- While at it, also double the watchdog delay: while I don't remember seeing
much failures due to client timeout, this change doesn't impact normal
running time of the script, so better err on the safe side.
These changes don't affect the test and should only affect the false positive
rate coming from the test framework in those scripts.
In wait_server_start, fork less. When lsof is present, call it on the
expected process. This saves a few percent of execution time on a
lightly loaded machine. Also, sleep for a short duration rather than
using a tight loop.
Add a DTLS small packet test for each of the following combinations:
- DTLS version: 1.0 or 1.2
- Encrypt then MAC extension enabled
- Truncated HMAC extension enabled
Large packets tests for DTLS are currently not possible due to parameter
constraints in ssl_server2.
This commit ensures that there is a small packet test for at least any
combination of
- SSL/TLS version: SSLv3, TLS 1.0, TLS 1.1 or TLS 1.2
- Stream cipher (RC4) or Block cipher (AES)
- Usage of Encrypt then MAC extension [TLS only]
- Usage of truncated HMAC extension [TLS only]
Noticed that the test cases in ssl-opt.sh exercising the truncated HMAC
extension do not depend on MBEDTLS_SSL_TRUNCATED_HMAC being enabled in
config.h. This commit fixes this.
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`.
