Commit graph

5153 commits

Author SHA1 Message Date
Janos Follath 0c1ed84258 Improve style 2019-06-28 15:10:06 +01:00
Gilles Peskine 9717d107ca Explain that lifetime=0 from static initialization means VOLATILE 2019-06-26 20:01:35 +02:00
Gilles Peskine a8ade16ffd Gate secure element support by a separate config option
Secure element support has its own source file, and in addition
requires many hooks in other files. This is a nontrivial amount of
code, so make it optional (but default on).
2019-06-26 20:01:35 +02:00
Janos Follath 40e1393816 Optimize TLS PRF PSK key calculation 2019-06-26 13:23:10 +01:00
Janos Follath 76c3984477 Clarify TLS PRF algorithm description 2019-06-26 12:50:36 +01:00
Ashley Duncan d85a7e9b09 Remove use of CMAKE_SOURCE_DIR
Remove use of CMAKE_SOURCE_DIR in case mbedtls is built from within
another CMake project. Define MBEDTLS_DIR to ${CMAKE_CURRENT_SOURCE_DIR}
in the main CMakeLists.txt file and refer to that when defining target
include paths to enable mbedtls to be built as a sub project.

Fixes https://github.com/ARMmbed/mbedtls/issues/2609

Signed-off-by: Ashley Duncan <ashes.man@gmail.com>
Signed-off-by: Jaeden Amero <jaeden.amero@arm.com>
2019-06-26 12:46:53 +01:00
Janos Follath 30090bc2cf Fix error code
PSA_ERROR_BAD_STATE means that the function was called on a context in a
bad state.

This error is something that can't happen while only using the PSA API and
therefore a PSA_ERROR_CORRUPTION_DETECTED is a more appropriate error
code.
2019-06-26 09:15:08 +01:00
Janos Follath 5fe19734d5 Make key derivation initialisation consistent
The macro initialiser might leave bytes in the union unspecified.
Zeroising it in setup makes sure that the behaviour is the same
independently of the initialisation method used.
2019-06-26 09:15:08 +01:00
Janos Follath ea29bfb148 Add tls12_prf key derivation to the new API
The TLS 1.2 pseudorandom function does a lot of distinct HMAC operations
with the same key. To save the battery and CPU cycles spent on
calculating the paddings and hashing the inner padding, we keep the
hash context in the status right after the inner padding having been
hashed and clone it as needed.
2019-06-26 09:15:08 +01:00
Janos Follath 844eb0e5fa Add tls12_prf_read for the new API
Technically we could have reused the old one for the new API, but then
we had to set an extra field during setup. The new version works when
all the fields that haven't been set explicitely are zero-initialised.
2019-06-26 09:15:08 +01:00
Janos Follath 7742feea53 Add stub for new tls12_prf_generate_next_block 2019-06-26 09:15:08 +01:00
Janos Follath 6c6c8fceaa Improve style 2019-06-26 09:15:08 +01:00
Janos Follath 6660f0eb98 Add TLS 1.2 PSK master secret generation 2019-06-26 09:15:08 +01:00
Janos Follath 51f4a0f9ac Style: enforce 80 column limit 2019-06-26 09:15:08 +01:00
Janos Follath c56215163f Simplify psa_key_derivation_input_bytes
The specific key derivation input functions support a subset of the
input options and need to check it anyway. Checking it at the top level
is redundant, it brings a very little value and comes with a cost in
code size and maintainability.
2019-06-26 09:15:08 +01:00
Janos Follath adbec81cc4 Remove the deprecated PSA_ALG_SELECT_RAW option
This change affects the psa_key_derivation_s structure. With the buffer
removed from the union, it is empty if MBEDTLS_MD_C is not defined.

We can avoid undefined behaviour by adding a new dummy field that is
always present or make the whole union conditional on MBEDTLS_MD_C.

In this latter case the initialiser macro has to depend on MBEDTLS_MD_C
as well. Furthermore the first structure would be either
psa_hkdf_key_derivation_t or psa_tls12_prf_key_derivation_t both of
which are very deep and would make the initialisation macro difficult
to maintain, therefore we go with the first option.
2019-06-26 09:15:08 +01:00
Janos Follath 63028dd906 Add label input for psa_tls12_prf_input 2019-06-26 09:15:08 +01:00
Janos Follath 8155054e28 Add key import for psa_tls12_prf_input 2019-06-26 09:15:08 +01:00
Janos Follath f08e2654ed Add seed input for psa_tls12_prf_input 2019-06-26 09:15:08 +01:00
Janos Follath ef83f5e98e Move raw key derivation input to a new function 2019-06-26 09:15:08 +01:00
Janos Follath b80a94e2ea Rename psa_key_derivation_input_raw
The function dispatches between all the available methods and
does not just handle the raw key derivation case like the name suggests.
2019-06-26 09:15:08 +01:00
Janos Follath b03233e196 Add stubs for psa_tls12_prf_input 2019-06-26 09:15:08 +01:00
Janos Follath 6a1d262803 Adapt psa_key_derivation_abort to the new context 2019-06-26 09:15:08 +01:00
Janos Follath 999f648437 Add new psa_tls12_prf_key_derivation_t
As part of adapting TLS 1.2 key derivation to the PSA 1.0 API we need to
change the context structure.
2019-06-26 09:15:08 +01:00
Janos Follath 083036af64 Safely erase key material upon abort
Some key derivation operation contexts (like
psa_tls12_prf_key_derivation_t) directly contain buffers with parts of
the derived key. Erase them safely as part of the abort.
2019-06-26 09:15:58 +01:00
Janos Follath 71a4c9125b Add flag for removing deprecated API
Add the compile time option PSA_PRE_1_0_KEY_DERIVATION. If this is not
turned on, then the function `psa_key_derivation()` is removed.

Most of the tests regarding key derivation haven't been adapted to the
new API yet and some of them have only been adapted partially. When this
new option is turned off, the tests using the old API and test cases
using the old API of partially adapted tests are skipped.

The sole purpose of this option is to make the transition to the new API
smoother. Once the transition is complete it can and should be removed
along with the old API and its implementation.
2019-06-26 09:15:08 +01:00
Gilles Peskine c2d56a4446 Allow declarations after statements
We officially allow C99, so don't forbid this C99 feature.
2019-06-25 18:52:06 +02:00
Ashley Duncan 3278081428 Remove use of CMAKE_SOURCE_DIR
Remove use of CMAKE_SOURCE_DIR in case mbedtls is built from within
another CMake project. Define MBEDTLS_DIR to ${CMAKE_CURRENT_SOURCE_DIR}
in the main CMakeLists.txt file and refer to that when defining target
include paths to enable mbedtls to be built as a sub project.

Fixes #2609

Signed-off-by: Ashley Duncan <ashes.man@gmail.com>
Signed-off-by: Jaeden Amero <jaeden.amero@arm.com>
2019-06-25 13:33:51 +01:00
Gilles Peskine 8f2a6dcc25 Support PSA_KEY_DERIVATION_INPUT_SEED 2019-06-25 12:02:31 +01:00
Gilles Peskine d089021128 Unregister drivers on library deinitialization 2019-06-24 19:55:48 +02:00
Gilles Peskine a899a72fd0 Implement the secure element driver registration function 2019-06-24 19:55:44 +02:00
Gilles Peskine bc2adf94a8 Fix minor type choice inconsistency 2019-06-24 15:45:09 +02:00
Sébastien Duquette 661d725044 Deref pointer when using sizeof in x509_get_other_name
Fix for #2716.
2019-06-24 09:17:18 -04:00
Jaeden Amero 66b7edb108 Merge remote-tracking branch 'origin/pr/2711' into development
* origin/pr/2711:
  programs: Make `make clean` clean all programs always
  ssl_tls: Enable Suite B with subset of ECP curves
  windows: Fix Release x64 configuration
  platform: Include stdarg.h where needed
  timing: Remove redundant include file
  net_sockets: Fix typo in net_would_block()
2019-06-21 14:09:10 +01:00
Jaeden Amero fd0f65459c Merge remote-tracking branch 'origin/pr/2697' into development
* origin/pr/2697:
  Update crypto submodule
  Add all.sh component that exercises invalid_param checks
  Remove mbedtls_param_failed from programs
  Make it easier to define MBEDTLS_PARAM_FAILED as assert
  Make test suites compatible with #include <assert.h>
  Pass -m32 to the linker as well
  Don't systematically rebuild programs
2019-06-21 13:21:05 +01:00
Jaeden Amero e2d5b9e5cc Merge remote-tracking branch 'origin/pr/2690' into development
* origin/pr/2690:
  Making version features easily ROM-able when using Arm C compiler.
2019-06-21 13:20:22 +01:00
Jaeden Amero d431104926 ssl_tls: Enable Suite B with subset of ECP curves
Make sure the code compiles even if some curves are not defined.

Fixes #1591
2019-06-20 10:59:05 +01:00
Jaeden Amero a180926556 timing: Remove redundant include file
There is no need to include winbase.h, as it will be pulled in by
windows.h as needed.

Fixes #2640
2019-06-20 10:51:21 +01:00
Jaeden Amero a152e42e9b net_sockets: Fix typo in net_would_block()
Fixes #528
2019-06-20 10:48:11 +01:00
Gilles Peskine 7846299adb Fix misuse of signed ints in the HAVEGE module
The elements of the HAVEGE state are manipulated with bitwise
operations, with the expectations that the elements are 32-bit
unsigned integers (or larger). But they are declared as int, and so
the code has undefined behavior. Clang with Asan correctly points out
some shifts that reach the sign bit.

Since these are supposed to be 32-bit unsigned integers, declare them
as uint32_t.

This is technically an API break, since the type mbedtls_havege_state
is exposed in a public header. However normal applications should not
be affected.
2019-06-14 19:23:10 +02:00
Jaeden Amero 7af080a9f9 Merge remote-tracking branch 'origin/pr/2442' into development
* origin/pr/2442:
  Correct placement of ChangeLog entry
  Improve documentation of mbedtls_x509_get_ext()
  Adapt ChangeLog
  Always return a high-level error code from X.509 module
  Obey bounds of ASN.1 substructures
2019-06-14 15:27:42 +01:00
Jaeden Amero e1b02df515 Merge remote-tracking branch 'origin/pr/2260' into development
* origin/pr/2260:
  Update crypto submodule
  Remove heading spaces in tests/data_files/Makefile
  Re-generate library/certs.c from script
  Add new line at the end of test-ca2.key.enc
  Use strict syntax to annotate origin of test data in certs.c
  Add run to all.sh exercising !MBEDTLS_PEM_PARSE_C + !MBEDTLS_FS_IO
  Allow DHM self test to run without MBEDTLS_PEM_PARSE_C
  ssl-opt.sh: Auto-skip tests that use files if MBEDTLS_FS_IO unset
  Document origin of hardcoded certificates in library/certs.c
  Adapt ChangeLog
  Rename server1.der to server1.crt.der
  Add DER encoded files to git tree
  Add build instructions to generate DER versions of CRTs and keys
  Document "none" value for ca_path/ca_file in ssl_client2/ssl_server2
  ssl_server2: Skip CA setup if `ca_path` or `ca_file` argument "none"
  ssl_client2: Skip CA setup if `ca_path` or `ca_file` argument "none"
  Correct white spaces in ssl_server2 and ssl_client2
  Adapt ssl_client2 to parse DER encoded test CRTs if PEM is disabled
  Adapt ssl_server2 to parse DER encoded test CRTs if PEM is disabled
2019-06-14 08:46:48 +01:00
Gilles Peskine c7ad122f51 Make it easier to define MBEDTLS_PARAM_FAILED as assert
Introduce a new configuration option MBEDTLS_CHECK_PARAMS_ASSERT,
which is disabled by default. When this option is enabled,
MBEDTLS_PARAM_FAILED defaults to assert rather than to a call to
mbedtls_param_failed, and <assert.h> is included.

This fixes #2671 (no easy way to make MBEDTLS_PARAM_FAILED assert)
without breaking backward compatibility. With this change,
`config.pl full` runs tests with MBEDTLS_PARAM_FAILED set to assert,
so the tests will fail if a validation check fails, and programs don't
need to provide their own definition of mbedtls_param_failed().
2019-06-13 16:51:59 +02:00
Máté Varga c5de4623e8 Making version features easily ROM-able when using Arm C compiler. 2019-06-12 12:26:37 +02:00
Gilles Peskine 4bac9a4c4b New function to get key slot statistics
New function mbedtls_psa_get_stats to obtain some data about how many
key slots are in use. This is intended for debugging and testing
purposes.
2019-06-05 16:38:42 +02:00
Jaeden Amero 2de07f1dd1 ssl: Don't access non-existent encrypt_then_mac field
When MBEDTLS_SSL_ENCRYPT_THEN_MAC is enabled, but not
MBEDTLS_SSL_SOME_MODES_USE_MAC, mbedtls_ssl_derive_keys() and
build_transforms() will attempt to use a non-existent `encrypt_then_mac`
field in the ssl_transform.

    Compile [ 93.7%]: ssl_tls.c
    [Error] ssl_tls.c@865,14: 'mbedtls_ssl_transform {aka struct mbedtls_ssl_transform}' ha
s no member named 'encrypt_then_mac'
    [ERROR] ./mbed-os/features/mbedtls/src/ssl_tls.c: In function 'mbedtls_ssl_derive_keys'
:
    ./mbed-os/features/mbedtls/src/ssl_tls.c:865:14: error: 'mbedtls_ssl_transform {aka str
uct mbedtls_ssl_transform}' has no member named 'encrypt_then_mac'
         transform->encrypt_then_mac = session->encrypt_then_mac;
                  ^~

Change mbedtls_ssl_derive_keys() and build_transforms() to only access
`encrypt_then_mac` if `encrypt_then_mac` is actually present.

Add a regression test to detect when we have regressions with
configurations that do not include any MAC ciphersuites.

Fixes d56ed2491b ("Reduce size of `ssl_transform` if no MAC ciphersuite is enabled")
2019-06-05 14:09:29 +01:00
Jaeden Amero 7654161dbf psa: Add NV seed as an entropy source when needed
When MBEDTLS_PSA_INJECT_ENTROPY is used, we now require also defining
MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES. When
MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES is defined, we do not add entropy
sources by default. This includes the NV seed entropy source, which the
PSA entropy injection API is built upon.

The PSA entropy injection feature depends on using NV seed as an entropy
source. Add NV seed as an entropy source for PSA entropy injection.

Fixes e3dbdd8d90 ("Gate entropy injection through a dedicated configuration option")
2019-06-05 11:09:38 +01:00
Gilles Peskine bfcae2e436 Improve documentation of psa_internal_allocate_key_slot 2019-06-05 11:39:57 +02:00
Gilles Peskine 70e085a7d9 Simplify psa_open_key
Simplify psa_open_key now that the old method for key creation
(returning a handle to a slot with no key material) no longer exists.
2019-06-05 11:34:54 +02:00
Gilles Peskine 267c65666a Simplify key slot allocation
Now that psa_allocate_key() is no longer a public function, expose
psa_internal_allocate_key_slot() instead, which provides a pointer to
the slot to its caller.
2019-06-05 11:34:54 +02:00
Gilles Peskine d2d45c1738 Convert cipher and pk to PSA attribute-based key creation
This fixes the build under MBEDTLS_USE_PSA_CRYPTO.
2019-06-05 11:34:54 +02:00
Gilles Peskine f46f81ceb5 Remove obsolete key creation functions
Remove the key creation functions from before the attribute-based API,
i.e. the key creation functions that worked by allocating a slot, then
setting metadata through the handle and finally creating key material.
2019-06-05 11:34:54 +02:00
Hanno Becker 3cddba887a Improve documentation of mbedtls_x509_get_ext()
- Explain the use of explicit ASN.1 tagging for the extensions structuree
- Remove misleading comment which suggests that mbedtls_x509_get_ext()
  also parsed the header of the first extension, which is not the case.
2019-06-04 13:59:55 +01:00
Hanno Becker 6ccfb18ab1 Always return a high-level error code from X.509 module
Some functions within the X.509 module return an ASN.1 low level
error code where instead this error code should be wrapped by a
high-level X.509 error code as in the bulk of the module.

Specifically, the following functions are affected:
- mbedtls_x509_get_ext()
- x509_get_version()
- x509_get_uid()

This commit modifies these functions to always return an
X.509 high level error code.

Care has to be taken when adapting `mbetls_x509_get_ext()`:
Currently, the callers `mbedtls_x509_crt_ext()` treat the
return code `MBEDTLS_ERR_ASN1_UNEXPECTED_TAG` specially to
gracefully detect and continue if the extension structure is not
present. Wrapping the ASN.1 error with
`MBEDTLS_ERR_X509_INVALID_EXTENSIONS` and adapting the check
accordingly would mean that an unexpected tag somewhere
down the extension parsing would be ignored by the caller.

The way out of this is the following: Luckily, the extension
structure is always the last field in the surrounding structure,
so if there is some data remaining, it must be an Extension
structure, so we don't need to deal with a tag mismatch gracefully
in the first place.

We may therefore wrap the return code from the initial call to
`mbedtls_asn1_get_tag()` in `mbedtls_x509_get_ext()` by
`MBEDTLS_ERR_X509_INVALID_EXTENSIONS` and simply remove
the special treatment of `MBEDTLS_ERR_ASN1_UNEXPECTED_TAG`
in the callers `x509_crl_get_ext()` and `x509_crt_get_ext()`.

This renders `mbedtls_x509_get_ext()` unsuitable if it ever
happened that an Extension structure is optional and does not
occur at the end of its surrounding structure, but for CRTs
and CRLs, it's fine.

The following tests need to be adapted:
- "TBSCertificate v3, issuerID wrong tag"
  The issuerID is optional, so if we look for its presence
  but find a different tag, we silently continue and try
  parsing the subjectID, and then the extensions. The tag '00'
  used in this test doesn't match either of these, and the
  previous code would hence return LENGTH_MISMATCH after
  unsucessfully trying issuerID, subjectID and Extensions.
  With the new code, any data remaining after issuerID and
  subjectID _must_ be Extension data, so we fail with
  UNEXPECTED_TAG when trying to parse the Extension data.
- "TBSCertificate v3, UIDs, invalid length"
  The test hardcodes the expectation of
  MBEDTLS_ERR_ASN1_INVALID_LENGTH, which needs to be
  wrapped in MBEDTLS_ERR_X509_INVALID_FORMAT now.

Fixes #2431.
2019-06-04 13:59:48 +01:00
Hanno Becker 12f62fb82c Obey bounds of ASN.1 substructures
When parsing a substructure of an ASN.1 structure, no field within
the substructure must exceed the bounds of the substructure.
Concretely, the `end` pointer passed to the ASN.1 parsing routines
must be updated to point to the end of the substructure while parsing
the latter.

This was previously not the case for the routines
- x509_get_attr_type_and_value(),
- mbedtls_x509_get_crt_ext(),
- mbedtls_x509_get_crl_ext().
These functions kept using the end of the parent structure as the
`end` pointer and would hence allow substructure fields to cross
the substructure boundary. This could lead to successful parsing
of ill-formed X.509 CRTs.

This commit fixes this.

Care has to be taken when adapting `mbedtls_x509_get_crt_ext()`
and `mbedtls_x509_get_crl_ext()`, as the underlying function
`mbedtls_x509_get_ext()` returns `0` if no extensions are present
but doesn't set the variable which holds the bounds of the Extensions
structure in case the latter is present. This commit addresses
this by returning early from `mbedtls_x509_get_crt_ext()` and
`mbedtls_x509_get_crl_ext()` if parsing has reached the end of
the input buffer.

The following X.509 parsing tests need to be adapted:
- "TBSCertificate, issuer two inner set datas"
  This test exercises the X.509 CRT parser with a Subject name
  which has two empty `AttributeTypeAndValue` structures.
  This is supposed to fail with `MBEDTLS_ERR_ASN1_OUT_OF_DATA`
  because the parser should attempt to parse the first structure
  and fail because of a lack of data. Previously, it failed to
  obey the (0-length) bounds of the first AttributeTypeAndValue
  structure and would try to interpret the beginning of the second
  AttributeTypeAndValue structure as the first field of the first
  AttributeTypeAndValue structure, returning an UNEXPECTED_TAG error.
- "TBSCertificate, issuer, no full following string"
  This test exercises the parser's behaviour on an AttributeTypeAndValue
  structure which contains more data than expected; it should therefore
  fail with MBEDTLS_ERR_ASN1_LENGTH_MISMATCH. Because of the missing bounds
  check, it previously failed with UNEXPECTED_TAG because it interpreted
  the remaining byte in the first AttributeTypeAndValue structure as the
  first byte in the second AttributeTypeAndValue structure.
- "SubjectAltName repeated"
  This test should exercise two SubjectAltNames extensions in succession,
  but a wrong length values makes the second SubjectAltNames extension appear
  outside of the Extensions structure. With the new bounds in place, this
  therefore fails with a LENGTH_MISMATCH error. This commit adapts the test
  data to put the 2nd SubjectAltNames extension inside the Extensions
  structure, too.
2019-06-04 10:15:09 +01:00
Hanno Becker ff552f7d56 Re-generate library/certs.c from script 2019-06-03 17:46:56 +01:00
Hanno Becker 92b4f8131c Use strict syntax to annotate origin of test data in certs.c
This allows to auto-generate them from scripts.
2019-06-03 17:46:56 +01:00
Hanno Becker 3217c8d7e8 Allow DHM self test to run without MBEDTLS_PEM_PARSE_C 2019-06-03 17:46:56 +01:00
Hanno Becker 960e588278 Document origin of hardcoded certificates in library/certs.c
All of them are copied from (former) CRT and key files in `tests/data_files`.
For files which have been regenerated since they've been copied to `certs.c`,
update the copy.

Add declarations for DER encoded test CRTs to certs.h

Add DER encoded versions of CRTs to certs.c

fix comment in certs.c

Don't use (signed) char for DER encoded certificates

Consistently use `const char *` for test CRTs regardless of encoding

Remove non-sensical and unused PW variable for DER encoded key

Provide test CRTs in PEM and DER fmt, + pick suitable per config

This commit modifies `certs.h` and `certs.c` to start following the
following pattern for the provided test certificates and files:

- Raw test data is named `NAME_ATTR1_ATTR2_..._ATTRn`

  For example, there are
     `TEST_CA_CRT_{RSA|EC}_{PEM|DER}_{SHA1|SHA256}`.

- Derived test data with fewer attributes, iteratively defined as one
  of the raw test data instances which suits the current configuration.

  For example,
     `TEST_CA_CRT_RSA_PEM`
  is one of `TEST_CA_CRT_RSA_PEM_SHA1` or `TEST_CA_CRT_RSA_PEM_SHA256`,
  depending on whether SHA-1 and/or SHA-256 are defined in the current
  config.

Add missing public declaration of test key password

Fix signedness and naming mismatches

Further improve structure of certs.h and certs.c

Fix definition of mbedtls_test_cas test CRTs depending on config

Remove semicolon after macro string constant in certs.c
2019-06-03 17:46:56 +01:00
Hanno Becker e8d6afd627 Add debug line witnessing receipt of unexpected CID 2019-06-03 16:07:50 +01:00
Hanno Becker 92d30f5bcf Fix indentation in debug message in ssl_tls.c 2019-06-03 16:07:50 +01:00
Hanno Becker 8e55b0f852 Improve comment in ssl_parse_record_header() 2019-06-03 16:07:50 +01:00
Hanno Becker 615ef17b67 Allow passing NULL pointers to mbedtls_ssl_get_peer_cid()
This commit modifies mbedtls_ssl_get_peer_cid() to also allow passing
NULL pointers in the arguments for the peer's CID value and length, in
case this information is needed.

For example, some users might only be interested in whether the use of
the CID was negotiated, in which case both CID value and length pointers
can be set to NULL. Other users might only be interested in confirming
that the use of CID was negotiated and the peer chose the empty CID,
in which case the CID value pointer only would be set to NULL.
It doesn't make sense to pass a NULL pointer for the CID length but a
non-NULL pointer for the CID value, as the caller has no way of telling
the length of the returned CID - and this case is therefore forbidden.
2019-06-03 16:07:50 +01:00
Hanno Becker a0e20d04b2 Rename MBEDTLS_SSL_CID to MBEDTLS_SSL_DTLS_CONNECTION_ID
Files modified via

sed -i 's/MBEDTLS_SSL_CID\([^_]\|$\)/MBEDTLS_SSL_DTLS_CONNECTION_ID\1/g' **/*.c **/*.h **/*.sh **/*.function
2019-06-03 16:07:50 +01:00
Hanno Becker ebcc9137ca Consistently reference CID draft through name + URL 2019-06-03 16:07:50 +01:00
Hanno Becker d1f203557f Slightly reorder CID debug messages during creation of transforms 2019-06-03 16:07:50 +01:00
Hanno Becker 4cac442211 Update references to CID draft to version 5 2019-06-03 16:07:50 +01:00
Hanno Becker 611ac77127 Fix mbedtls_ssl_conf_cid() to not depend on macro constant values
The previous implementation of mbedtls_ssl_conf_cid() relied on
MBEDTLS_SSL_UNEXPECTED_CID_IGNORE being defined as 1.
2019-06-03 16:07:50 +01:00
Hanno Becker 5d12467fad Remove warnings about unfinished CID implementation
The implementation is complete now.
2019-06-03 16:07:50 +01:00
Hanno Becker 8367ccc03b Allow to configure the stack's behaviour on unexpected CIDs
This commit modifies the CID configuration API mbedtls_ssl_conf_cid_len()
to allow the configuration of the stack's behaviour when receiving an
encrypted DTLS record with unexpected CID.
2019-06-03 16:07:50 +01:00
Hanno Becker c37c96a3c5 Add specific SSL error code for unexpected CIDs
Currently, the stack silently ignores DTLS frames with an unexpected CID.
However, in a system which performs CID-based demultiplexing before passing
datagrams to the Mbed TLS stack, unexpected CIDs are a sign of something not
working properly, and users might want to know about it.

This commit introduces an SSL error code MBEDTLS_ERR_SSL_UNEXPECTED_CID
which the stack can return in response to an unexpected CID. It will
conditionally be put to use in subsequent commits.
2019-06-03 16:07:50 +01:00
Hanno Becker b9ec44fcf6 Remove restriction on value of MBEDTLS_SSL_CID_PADDING_GRANULARITY 2019-06-03 16:07:50 +01:00
Hanno Becker 2cdc5c3cf9 Make signed to unsigned integer truncation cast explicit 2019-06-03 16:07:50 +01:00
Hanno Becker b1aa1b3616 Allow the configuration of padding when using CID extension 2019-06-03 16:07:50 +01:00
Hanno Becker 4c3eb7c919 Set CID pointer to default value even for TLS
There are two options:
1. Don't set it, and don't use it during record protection,
   guarding the respective paths by a check whether TLS or
   DTLS is used.
2. Set it to the default value even for TLS, and avoid the
   protocol-dependent branch during record protection.

This commit picks option 2.
2019-06-03 16:07:50 +01:00
Hanno Becker 4a4af9fcbe Fix typo in comment 2019-06-03 16:07:50 +01:00
Hanno Becker 22a59fdca8 Remove indicators and warnings about unfinished CID implementation 2019-06-03 16:07:50 +01:00
Hanno Becker 05154c3897 Re-enable passing CIDs to record transforms 2019-06-03 16:07:50 +01:00
Hanno Becker 16ded98bef Don't fail on record with unexpected CID
This commit changes the stack's behaviour when facing a record
with a non-matching CID. Previously, the stack failed in this
case, while now we silently skip over the current record.
2019-06-03 16:07:50 +01:00
Hanno Becker 938489a1bc Re-enable CID comparison when decrypting CID-based records 2019-06-03 16:07:50 +01:00
Hanno Becker ca59c2b486 Implement parsing of CID-based records
Previously, ssl_get_next_record() would fetch 13 Bytes for the
record header and hand over to ssl_parse_record_header() to parse
and validate these. With the introduction of CID-based records, the
record length is not known in advance, and parsing and validating
must happen at the same time. ssl_parse_record_header() is therefore
rewritten in the following way:
1. Fetch and validate record content type and version.
2. If the record content type indicates a record including a CID,
   adjust the record header pointers accordingly; here, we use the
   statically configured length of incoming CIDs, avoiding any
   elaborate CID parsing mechanism or dependency on the record
   epoch, as explained in the previous commit.
3. Fetch the rest of the record header (note: this doesn't actually
   fetch anything, but makes sure that the datagram fetched in the
   earlier call to ssl_fetch_input() contains enough data).
4. Parse and validate the rest of the record header as before.
2019-06-03 16:07:50 +01:00
Hanno Becker 6430faf098 Adapt record encryption/decryption routines to change of record type
This commit modifies the code surrounding the invocations of
ssl_decrypt_buf() and ssl_encrypt_buf() to deal with a change
of record content type during CID-based record encryption/decryption.
2019-06-03 16:07:50 +01:00
Hanno Becker f9c6a4bea1 Add pointers to in/out CID fields to mbedtls_ssl_context
mbedtls_ssl_context contains pointers in_buf, in_hdr, in_len, ...
which point to various parts of the header of an incoming TLS or
DTLS record; similarly, there are pointers out_buf, ... for
outgoing records.

This commit adds fields in_cid and out_cid which point to where
the CID of incoming/outgoing records should reside, if present,
namely prior to where the record length resides.

Quoting https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-04:

   The DTLSInnerPlaintext value is then encrypted and the CID added to
   produce the final DTLSCiphertext.

        struct {
            ContentType special_type = tls12_cid; /* 25 */
            ProtocolVersion version;
            uint16 epoch;
            uint48 sequence_number;
            opaque cid[cid_length];               // New field
            uint16 length;
            opaque enc_content[DTLSCiphertext.length];
        } DTLSCiphertext;

For outgoing records, out_cid is set in ssl_update_out_pointers()
based on the settings in the current outgoing transform.

For incoming records, ssl_update_in_pointers() sets in_cid as if no
CID was present, and it is the responsibility of ssl_parse_record_header()
to update the field (as well as in_len, in_msg and in_iv) when parsing
records that do contain a CID. This will be done in a subsequent commit.

Finally, the code around the invocations of ssl_decrypt_buf()
and ssl_encrypt_buf() is adapted to transfer the CID from the
input/output buffer to the CID field in the internal record
structure (which is what ssl_{encrypt/decrypt}_buf() uses).

Note that mbedtls_ssl_in_hdr_len() doesn't need change because
it infers the header length as in_iv - in_hdr, which will account
for the CID for records using such.
2019-06-03 16:07:50 +01:00
Hanno Becker 6cbad5560d Account for additional record expansion when using CIDs
Using the Connection ID extension increases the maximum record expansion
because
- the real record content type is added to the plaintext
- the plaintext may be padded with an arbitrary number of
  zero bytes, in order to prevent leakage of information
  through package length analysis. Currently, we always
  pad the plaintext in a minimal way so that its length
  is a multiple of 16 Bytes.

This commit adapts the various parts of the library to account
for that additional source of record expansion.
2019-06-03 16:07:50 +01:00
Hanno Becker ad4a137965 Add CID configuration API
Context:
The CID draft does not require that the length of CIDs used for incoming
records must not change in the course of a connection. Since the record
header does not contain a length field for the CID, this means that if
CIDs of varying lengths are used, the CID length must be inferred from
other aspects of the record header (such as the epoch) and/or by means
outside of the protocol, e.g. by coding its length in the CID itself.

Inferring the CID length from the record's epoch is theoretically possible
in DTLS 1.2, but it requires the information about the epoch to be present
even if the epoch is no longer used: That's because one should silently drop
records from old epochs, but not the entire datagrams to which they belong
(there might be entire flights in a single datagram, including a change of
epoch); however, in order to do so, one needs to parse the record's content
length, the position of which is only known once the CID length for the epoch
is known. In conclusion, it puts a significant burden on the implementation
to infer the CID length from the record epoch, which moreover mangles record
processing with the high-level logic of the protocol (determining which epochs
are in use in which flights, when they are changed, etc. -- this would normally
determine when we drop epochs).

Moreover, with DTLS 1.3, CIDs are no longer uniquely associated to epochs,
but every epoch may use a set of CIDs of varying lengths -- in that case,
it's even theoretically impossible to do record header parsing based on
the epoch configuration only.

We must therefore seek a way for standalone record header parsing, which
means that we must either (a) fix the CID lengths for incoming records,
or (b) allow the application-code to configure a callback to implement
an application-specific CID parsing which would somehow infer the length
of the CID from the CID itself.

Supporting multiple lengths for incoming CIDs significantly increases
complexity while, on the other hand, the restriction to a fixed CID length
for incoming CIDs (which the application controls - in contrast to the
lengths of the CIDs used when writing messages to the peer) doesn't
appear to severely limit the usefulness of the CID extension.

Therefore, the initial implementation of the CID feature will require
a fixed length for incoming CIDs, which is what this commit enforces,
in the following way:

In order to avoid a change of API in case support for variable lengths
CIDs shall be added at some point, we keep mbedtls_ssl_set_cid(), which
includes a CID length parameter, but add a new API mbedtls_ssl_conf_cid_len()
which applies to an SSL configuration, and which fixes the CID length that
any call to mbetls_ssl_set_cid() which applies to an SSL context that is bound
to the given SSL configuration must use.

While this creates a slight redundancy of parameters, it allows to
potentially add an API like mbedtls_ssl_conf_cid_len_cb() later which
could allow users to register a callback which dynamically infers the
length of a CID at record header parsing time, without changing the
rest of the API.
2019-06-03 16:07:50 +01:00
Hanno Becker 5903de45b6 Split mbedtls_ssl_hdr_len() in separate functions for in/out records
The function mbedtls_ssl_hdr_len() returns the length of the record
header (so far: always 13 Bytes for DTLS, and always 5 Bytes for TLS).

With the introduction of the CID extension, the lengths of record
headers depends on whether the records are incoming or outgoing,
and also on the current transform.

Preparing for this, this commit splits mbedtls_ssl_hdr_len() in two
-- so far unmodified -- functions mbedtls_ssl_in_hdr_len() and
mbedtls_ssl_out_hdr_len() and replaces the uses of mbedtls_ssl_hdr_len()
according to whether they are about incoming or outgoing records.

There is no need to change the signature of mbedtls_ssl_{in/out}_hdr_len()
in preparation for its dependency on the currently active transform,
since the SSL context is passed as an argument, and the currently
active transform is referenced from that.
2019-06-03 16:07:50 +01:00
Hanno Becker f661c9c39c Add helper function to check validity of record content type
With the introduction of the CID feature, the stack needs to be able
to handle a change of record content type during record protection,
which in particular means that the record content type check will
need to move or be duplicated.

This commit introduces a tiny static helper function which checks
the validity of record content types, which hopefully makes it
easier to subsequently move or duplicate this check.
2019-06-03 16:07:50 +01:00
Hanno Becker 37ae952923 Move dropping of unexpected AD records to after record decryption
With the introduction of the CID extension, the record content type
may change during decryption; we must therefore re-consider every
record content type check that happens before decryption, and either
move or duplicate it to ensure it also applies to records whose
real content type is only revealed during decryption.

This commit does this for the silent dropping of unexpected
ApplicationData records in DTLS. Previously, this was caught
in ssl_parse_record_header(), returning
MBEDTLS_ERR_SSL_UNEXPECTED_RECORD which in ssl_get_next_record()
would lead to silent skipping of the record.

When using CID, this check wouldn't trigger e.g. when delayed
encrypted ApplicationData records come on a CID-based connection
during a renegotiation.

This commit moves the check to mbedtls_ssl_handle_message_type()
and returns MBEDTLS_ERR_SSL_NON_FATAL if it triggers, which leads
so silent skipover in the caller mbedtls_ssl_read_record().
2019-06-03 16:07:50 +01:00
Hanno Becker 79594fd0d4 Set pointer to start of plaintext at record decryption time
The SSL context structure mbedtls_ssl_context contains several pointers
ssl->in_hdr, ssl->in_len, ssl->in_iv, ssl->in_msg pointing to various
parts of the record header in an incoming record, and they are setup
in the static function ssl_update_in_pointers() based on the _expected_
transform for the next incoming record.
In particular, the pointer ssl->in_msg is set to where the record plaintext
should reside after record decryption, and an assertion double-checks this
after each call to ssl_decrypt_buf().

This commit removes the dependency of ssl_update_in_pointers() on the
expected incoming transform by setting ssl->in_msg to ssl->in_iv --
the beginning of the record content (potentially including the IV) --
and adjusting ssl->in_msg after calling ssl_decrypt_buf() on a protected
record.

Care has to be taken to not load ssl->in_msg before calling
mbedtls_ssl_read_record(), then, which was previously the
case in ssl_parse_server_hello(); the commit fixes that.
2019-06-03 16:07:50 +01:00
Hanno Becker 82e2a3961c Treat an invalid record after decryption as fatal
If a record exhibits an invalid feature only after successful
authenticated decryption, this is a protocol violation by the
peer and should hence lead to connection failure. The previous
code, however, would silently ignore such records. This commit
fixes this.

So far, the only case to which this applies is the non-acceptance
of empty non-AD records in TLS 1.2. With the present commit, such
records lead to connection failure, while previously, they were
silently ignored.

With the introduction of the Connection ID extension (or TLS 1.3),
this will also apply to records whose real content type -- which
is only revealed during authenticated decryption -- is invalid.
2019-06-03 16:07:50 +01:00
Hanno Becker 6e7700df17 Expain rationale for handling of consecutive empty AD records 2019-06-03 16:07:50 +01:00
Hanno Becker 76a79ab4a2 Don't allow calling CID API outside of DTLS 2019-06-03 16:07:50 +01:00
Hanno Becker 95e4bbcf6c Fix additional data calculation if CID is disabled
In contrast to other aspects of the Connection ID extension,
the CID-based additional data for MAC computations differs from
the non-CID case even if the CID length is 0, because it
includes the CID length.
2019-06-03 14:47:36 +01:00
Hanno Becker af05ac067b Remove unnecessary empty line in ssl_tls.c 2019-06-03 14:47:36 +01:00
Hanno Becker 07dc97db8c Don't quote DTLSInnerPlaintext structure multiple times 2019-06-03 14:47:36 +01:00
Hanno Becker d3f8c79ea0 Improve wording in ssl_build_inner_plaintext() 2019-06-03 14:47:36 +01:00
Hanno Becker edb24f8eec Remove unnecessary whitespace in ssl_extract_add_data_from_record() 2019-06-03 14:47:36 +01:00
Hanno Becker 92fb4fa802 Reduce stack usage for additional data buffers in record dec/enc 2019-06-03 14:47:36 +01:00
Hanno Becker c4a190bb0f Add length of CID to additional data used for record protection
Quoting the CID draft 04:

   -  Block Ciphers:

       MAC(MAC_write_key, seq_num +
           tls12_cid +                     // New input
           DTLSPlaintext.version +
           cid +                           // New input
           cid_length +                    // New input
           length_of_DTLSInnerPlaintext +  // New input
           DTLSInnerPlaintext.content +    // New input
           DTLSInnerPlaintext.real_type +  // New input
           DTLSInnerPlaintext.zeros        // New input
       )

And similar for AEAD and Encrypt-then-MAC.
2019-06-03 14:47:36 +01:00
Hanno Becker d5aeab1e8a Improve documentation of ssl_extract_add_data_from_record() 2019-06-03 14:47:36 +01:00