According to RFC5246 the server can indicate the known Certificate
Authorities or can constrain the aurhorisation space by sending a
certificate list. This part of the message is optional and if omitted,
the client may send any certificate in the response.
The previous behaviour of mbed TLS was to always send the name of all the
CAs that are configured as root CAs. In certain cases this might cause
usability and privacy issues for example:
- If the list of the CA names is longer than the peers input buffer then
the handshake will fail
- If the configured CAs belong to third parties, this message gives away
information on the relations to these third parties
Therefore we introduce an option to suppress the CA list in the
Certificate Request message.
Providing this feature as a runtime option comes with a little cost in
code size and advantages in maintenance and flexibility.
This commit changes `ssl_parse_signature_algorithms_ext` to remember
one suitable ( := supported by client and by our config ) hash
algorithm per signature algorithm.
It also modifies the ciphersuite checking function
`ssl_ciphersuite_match` to refuse a suite if there
is no suitable hash algorithm.
Finally, it adds the corresponding entry to the ChangeLog.
The routine `mbedtls_ssl_write_server_key_exchange` heavily depends on
what kind of cipher suite is active: some don't need a
ServerKeyExchange at all, some need (EC)DH parameters but no server
signature, some require both. Each time we want to restrict a certain
piece of code to some class of ciphersuites, it is guarded by a
lengthy concatentation of configuration checks determining whether at
least one of the relevant cipher suites is enabled in the config; on
the code level, it is guarded by the check whether one of these
cipher suites is the active one.
To ease readability of the code, this commit introduces several helper
macros and helper functions that can be used to determine whether a
certain class of ciphersuites (a) is active in the config, and
(b) contains the currently present ciphersuite.
In many places in TLS handling, some code detects a fatal error, sends
a fatal alert message, and returns to the caller. If sending the alert
fails, then return the error that triggered the alert, rather than
overriding the return status. This effectively causes alert sending
failures to be ignored. Formerly the code was inconsistently sometimes
doing one, sometimes the other.
In general ignoring the alert is the right thing: what matters to the
caller is the original error. A typical alert failure is that the
connection is already closed.
One case which remains not handled correctly is if the alert remains
in the output buffer (WANT_WRITE). Then it won't be sent, or will be
truncated. We'd need to either delay the application error or record
the write buffering notice; to be done later.
The TLS client and server code was usually closing the connection in
case of a fatal error without sending an alert. This commit adds
alerts in many cases.
Added one test case to detect that we send the alert, where a server
complains that the client's certificate is from an unknown CA (case
tracked internally as IOTSSL-1330).
Separates platform time abstraction into it's own header from the
general platform abstraction as both depend on different build options.
(MBEDTLS_PLATFORM_C vs MBEDTLS_HAVE_TIME)
The server code parses the client hello extensions even when the
protocol is SSLv3 and this behaviour is non compliant with rfc6101.
Also the server sends extensions in the server hello and omitting
them may prevent interoperability problems.
By looking just at that test, it looks like 2 + dn_size could overflow. In
fact that can't happen as that would mean we've read a CA cert of size is too
big to be represented by a size_t.
However, it's best for code to be more obviously free of overflow without
having to reason about the bigger picture.
* development: (73 commits)
Bump yotta dependencies version
Fix typo in documentation
Corrected misleading fn description in ssl_cache.h
Corrected URL/reference to MPI library
Fix yotta dependencies
Fix minor spelling mistake in programs/pkey/gen_key.c
Bump version to 2.1.2
Fix CVE number in ChangeLog
Add 'inline' workaround where needed
Fix references to non-standard SIZE_T_MAX
Fix yotta version dependencies again
Upgrade yotta dependency versions
Fix compile error in net.c with musl libc
Add missing warning in doc
Remove inline workaround when not useful
Fix macroization of inline in C++
Changed attribution for Guido Vranken
Merge of IOTSSL-476 - Random malloc in pem_read()
Fix for IOTSSL-473 Double free error
Fix potential overflow in CertificateRequest
...
Conflicts:
include/mbedtls/ssl_internal.h
library/ssl_cli.c
This bug becomes noticeable when the extension following the "supported point
formats" extension has a number starting with 0x01, which is the case of the
EC J-PAKE extension, which explains what I noticed the bug now.
This will be immediately backported to the stable branches,
see the corresponding commits for impact analysis.
This is more consistent, as it doesn't make any sense for a user to be able to
set up an EC J-PAKE password with TLS if the corresponding key exchange is
disabled.
Arguably this is what we should de for other key exchanges as well instead of
depending on ECDH_C etc, but this is an independent issue, so let's just do
the right thing with the new key exchange and fix the other ones later. (This
is a marginal issue anyway, since people who disable all ECDH key exchange are
likely to also disable ECDH_C in order to minimize footprint.)
There is only one length byte but for some reason we skipped two, resulting in
reading one byte past the end of the extension. Fortunately, even if that
extension is at the very end of the ClientHello, it can't be at the end of the
buffer since the ClientHello length is at most SSL_MAX_CONTENT_LEN and the
buffer has some more room after that for MAC and so on. So there is no
buffer overread.
Possible consequences are:
- nothing, if the next byte is 0x00, which is a comment first byte for other
extensions, which is why the bug remained unnoticed
- using a point format that was not offered by the peer if next byte is 0x01.
In that case the peer will reject our ServerKeyExchange message and the
handshake will fail.
- thinking that we don't have a common point format even if we do, which will
cause us to immediately abort the handshake.
None of these are a security issue.
The same bug was fixed client-side in fd35af15
The Thread spec says we need those for EC J-PAKE too.
However, we won't be using the information, so we can skip the parsing
functions in an EC J-PAKE only config; keep the writing functions in order to
comply with the spec.
May happen with a faulty configuration (eg no allowed curve but trying to use
ECDHE key exchange), but not trigger able remotely.
(Found with Clang's scan-build.)
While at it, fix the following:
- on server with RSA_PSK, we don't want to set flags (client auth happens via
the PSK, no cert is expected).
- use safer tests (eg == OPTIONAL vs != REQUIRED)
A simple series of sed invocations.
This is the first step, purely internal changes. The conf substructure is not
ready to be shared between contexts yet.
* commit 'ce60fbe':
Fix potential timing difference with RSA PMS
Update Changelog for recent merge
Added more constant-time code and removed biases in the prime number generation routines.
Conflicts:
library/bignum.c
library/ssl_srv.c
Note from future self: actually md_init_ctx will be re-introduced with the
same signature later, and a new function with the additional argument will be
added.
- more freedom for us to change it in the future
- enforces hygiene
- performance impact of making accessors no longer inline should really be
negligible
Outline:
if( condition )
foo = value;
/* stuff that does not change condition */
if( condition )
/* use foo */
else
/* don't use foo */
For some reason, it appears to only kick in with -Os with gcc 4.9.3
* mbedtls-1.3:
Rename website and repository
Move private macro from header to C file
Add some missing 'static' on a few objects
Fix whitespace issues
Minor portability fix in benchmark
* development: (100 commits)
Update Changelog for the mem-measure branch
Fix issues introduced when rebasing
Fix compile error in memory_buffer_alloc_selftest
Code cosmetics
Add curve25519 to ecc-heap.sh
Add curve25519 to the benchmark program
Fix compile issue when buffer_alloc not available
New script ecc-heap.sh
Fix unused variable issue in some configs
Rm usunused member in private struct
Add heap usage for PK in benchmark
Use memory_buffer_alloc() in benchmark if available
Only define mode_func if mode is enabled (CBC etc)
PKCS8 encrypted key depend on PKCS5 or PKCS12
Disable SRV_C for client measurement
Output stack+heap usage with massif
Enable NIST_OPTIM by default for config-suite-b
Refactor memory.sh
Adapt memory.sh to config-suite-b
Adapt mini-client for config-suite-b.h
...
Conflicts:
ChangeLog
include/polarssl/net.h
library/Makefile
library/error.c
library/ssl_tls.c
programs/Makefile
programs/ssl/ssl_client2.c
programs/ssl/ssl_server2.c
tests/Makefile
Some people recommend using bit operations to avoid the compiler producing a
branch on `ret != 0`, but:
- this makes the code less readable,
- here I got a warning from some compilers about unsigned unary minus
- and anyway modern compilers don't produce a branch here, checked on x64 and
arm with various -O values.
* development: (46 commits)
Fix url again
Fix small bug in base64_encode()
Fix depend that was checked but not documented
Fix dependency that was not checked
Minor gitginore fixes
Move some ignore patterns to subdirectories
Ignore CMake/MSVC-related build files.
Re-categorize changelog entry
Fix misattribution
Minor nits with stdout/stderr.
Add cmake compatibility targets
Add script for polarssl symlink creation
Fix more stdio inclusion issues
Add debug info for cert/suite selection
Fix possible portability issue
Fix bug in ssl_get_verify_result()
aescrypt2.c local char array not initial
Update Changelog
Fix mips64 bignum implementation
Fix usage string of ssl_client2
...
Conflicts:
include/polarssl/ssl.h
library/CMakeLists.txt
library/Makefile
programs/Makefile
programs/ssl/ssl_client2.c
programs/ssl/ssl_server2.c
visualc/VS2010/PolarSSL.sln
visualc/VS2010/mbedTLS.vcxproj
visualc/VS6/mbedtls.dsp
visualc/VS6/mbedtls.dsw
