Commit graph

1146 commits

Author SHA1 Message Date
Manuel Pégourié-Gonnard 8175816200 Fix English in comments 2019-07-23 17:02:10 +02:00
Manuel Pégourié-Gonnard f1f3e529a5 Add session saving/loading
For now, the header (version+format bytes) is duplicated. This might be
optimized later.
2019-07-23 17:02:09 +02:00
Manuel Pégourié-Gonnard d0dd10469b Add (stub) header writing and checking
The number of meaning of the flags will be determined later, when handling the
relevant struct members. For now three bytes are reserved as an example, but
this number may change later.
2019-07-23 17:02:09 +02:00
Manuel Pégourié-Gonnard 5e534baaec Add usage checks in context_load() 2019-07-23 17:02:09 +02:00
Manuel Pégourié-Gonnard b6163ef175 Document internal serialisation format
This mainly follows the design document (saving all fields marked "saved" in
the main structure and the transform sub-structure) with two exceptions:

- things related to renegotiation are excluded here (there weren't quite in
  the design document as the possibility of allowing renegotiation was still
on the table, which is no longer is) - also, ssl.secure_renegotiation (which
is not guarded by MBEDTLS_SSL_RENEGOTIATION because it's used in initial
handshakes even with renegotiation disabled) is still excluded, as we don't
need it after the handshake.

- things related to Connection ID are added, as they weren't present at the
  time the design document was written.

The exact format of the header (value of the bitflag indicating compile-time
options, whether and how to merge it with the serialized session header) will
be determined later.
2019-07-23 17:02:09 +02:00
Manuel Pégourié-Gonnard 569ed6ba56 Implement usage checks in context_save()
Enforce restrictions indicated in the documentation.

This allows to make some simplifying assumptions (no need to worry about
saving IVs for CBC in TLS < 1.1, nor about saving handshake data) and
guarantees that all values marked as "forced" in the design document have the
intended values and can be skipped when serialising.

Some of the "forced" values are not checked because their value is a
consequence of other checks (for example, session_negotiated == NULL outside
handshakes). We do however check that session and transform are not NULL (even
if that's also a consequence of the initial handshake being over) as we're
going to dereference them and static analyzers may appreciate the info.
2019-07-23 17:02:09 +02:00
Manuel Pégourié-Gonnard a3024eef7b Save Hello random bytes for later use 2019-07-23 17:02:09 +02:00
Hanno Becker 95d1b93c69 Don't reset timer during mbedtls_ssl_setup()
At that point, the timer might not yet be configured.

The timer is reset at the following occasions:

- when it is initially configured through
    mbedtls_ssl_set_timer_cb() or
    mbedtls_ssl_set_timer_cb_cx()
- when a session is reset in mbedtls_ssl_session_reset()
- when a handshake finishes via mbedtls_ssl_handshake_wrap()
2019-07-22 11:15:28 +01:00
Hanno Becker 56595f4f7b Allow hardcoding single signature hash at compile-time
This commit introduces the option MBEDTLS_SSL_CONF_SINGLE_HASH
which can be used to register a single supported signature hash
algorithm at compile time. It replaces the runtime configuration
API mbedtls_ssl_conf_sig_hashes() which allows to register a _list_
of supported signature hash algorithms.

In contrast to other options used to hardcode configuration options,
MBEDTLS_SSL_CONF_SINGLE_HASH isn't a numeric option, but instead it's
only relevant if it's defined or not. To actually set the single
supported hash algorithm that should be supported, numeric options

MBEDTLS_SSL_CONF_SINGLE_HASH_TLS_ID
MBEDTLS_SSL_CONF_SINGLE_HASH_MD_ID

must both be defined and provide the TLS ID and the Mbed TLS internal
ID and the chosen hash algorithm, respectively.
2019-07-17 10:19:27 +01:00
Hanno Becker f1bc9e1c69 Introduce helper functions to traverse signature hashes 2019-07-17 10:19:27 +01:00
Hanno Becker 627fbee41a Don't offer SHA-1 in CertificateRequest message in TLS 1.2
mbedtls_ssL_set_calc_verify_md() is used to select valid hashes when
writing the server's CertificateRequest message, as well as to verify
and act on the client's choice when reading its CertificateVerify
message.

If enabled at compile-time and configured via mbedtls_ssl_conf_sig_hashes()
the current code also offers SHA-1 in TLS 1.2. However, the SHA-1-based
handshake transcript in TLS 1.2 is different from the SHA-1 handshake
transcript used in TLS < 1.2, and we only maintain the latter
(through ssl_update_checksum_md5sha1()), but not the former.
Concretely, this will lead to CertificateVerify verification failure
if the client picks SHA-1 for the CertificateVerify message in a TLS 1.2
handshake.

This commit removes SHA-1 from the list of supported hashes in
the CertificateRequest message, and adapts two tests in ssl-opt.sh
which expect SHA-1 to be listed in the CertificateRequest message.
2019-07-17 10:19:27 +01:00
Hanno Becker 0a6417041e Remove redundant check in mbedtls_ssl_set_calc_verify_md()
mbedtls_ssl_set_calc_verify_md() is only called from places
where it has been checked that TLS 1.2 is being used. The
corresponding compile-time and runtime guards checking the
version in mbedtls_ssl_set_calc_verify_md() are therefore
redundant and can be removed.
2019-07-17 10:19:25 +01:00
Simon Butcher feb1cee36e Merge remote-tracking branch 'origin/pr/602' into baremetal 2019-07-15 19:24:11 +01:00
Hanno Becker c1096e7514 Allow hardcoding single supported elliptic curve
This commit introduces the option MBEDTLS_SSL_CONF_SINGLE_EC
which can be used to register a single supported elliptic curve
at compile time. It replaces the runtime configuration API
mbedtls_ssl_conf_curves() which allows to register a _list_
of supported elliptic curves.

In contrast to other options used to hardcode configuration options,
MBEDTLS_SSL_CONF_SINGLE_EC isn't a numeric option, but instead it's
only relevant if it's defined or not. To actually set the single
elliptic curve that should be supported, numeric options

MBEDTLS_SSL_CONF_SINGLE_EC_TLS_ID
MBEDTLS_SSL_CONF_SINGLE_EC_GRP_ID

must both be defined and provide the TLS ID and the Mbed TLS internal
ID and the chosen curve, respectively.
2019-07-12 15:25:03 +01:00
Hanno Becker ee24f8cecb Remove unnecessary check for presence of supported EC list
For both client/server the EC curve list is assumed not to be NULL:

- On the client-side, it's assumed when writing the
  supported elliptic curve extension:

    c54ee936d7/library/ssl_cli.c (L316)

- On the server, it is assumed when searching for a
  suitable curve for the ECDHE exchange:

    c54ee936d7/library/ssl_srv.c (L3200)

It is therefore not necessary to check this in mbedtls_ssl_check_curve().
2019-07-12 15:25:03 +01:00
Hanno Becker a4a9c696c1 Introduce helper macro for traversal of supported EC TLS IDs 2019-07-12 15:25:03 +01:00
Hanno Becker 33b9b25a48 Remove SSL version configuration API if versions are hardcoded 2019-07-12 15:15:08 +01:00
Hanno Becker 0a92b8156d Remove mbedtls_ssl_transform::minor_ver if the version is hardcoded 2019-07-12 15:15:08 +01:00
Hanno Becker 7b628e5b88 Make mbedtls_ssl_read/write_version static inline
Reasons:
- If the transport type is fixed at compile-time,
  mbedtls_ssl_read_version() and mbedtls_ssl_write_version()
  are called with a compile-time determined `transport`
  parameter, so the transport-type branch in their body
  can be eliminated at compile-time.
- mbedtls_ssl_read_version() is called with addresses of
  local variables, which so far need to be put on the stack
  to be addressable. Inlining the call allows to read directly
  into the registers holding these local variables.

This saves 60 bytes w.r.t. the measurement performed by

> ./scripts/baremetal.sh --rom --gcc
2019-07-12 15:15:07 +01:00
Hanno Becker 2881d80138 Introduce getter function for max/min SSL version
This is a first step towards hardcoding ssl->{major|minor}_ver
in configurations which accept only a single version.
2019-07-12 15:15:06 +01:00
Hanno Becker e965bd397e Allow hardcoding of min/max minor/major SSL version at compile-time
This commit introduces the numeric compile-time constants

- MBEDTLS_SSL_CONF_MIN_MINOR_VER
- MBEDTLS_SSL_CONF_MAX_MINOR_VER
- MBEDTLS_SSL_CONF_MIN_MAJOR_VER
- MBEDTLS_SSL_CONF_MAX_MAJOR_VER

which, when defined, overwrite the runtime configurable fields
mbedtls_ssl_config::min_major_ver etc. in the SSL configuration.

As for the preceding case of the ExtendedMasterSecret configuration,
it also introduces and puts to use getter functions for these variables
which evaluate to either a field access or the macro value, maintaining
readability of the code.

The runtime configuration API mbedtls_ssl_conf_{min|max}_version()
is kept for now but has no effect if MBEDTLS_SSL_CONF_XXX are set.
This is likely to be changed in a later commit but deliberately omitted
for now, in order to be able to study code-size benefits earlier in the
process.
2019-07-12 15:14:51 +01:00
Simon Butcher fabfb8578a Merge remote-tracking branch 'origin/pr/603' into baremetal 2019-07-10 15:40:32 +01:00
Hanno Becker 14a4a44e60 Remove mbedtls_ssl_conf_dbg() if !MBEDTLS_DEBUG_C 2019-07-08 11:32:50 +01:00
Hanno Becker 272063abfd Don't store debug func ptr cb + ctx in SSL config if !DEBUG_C
Note: This is an structure-API breaking change that we might
      not be able to upstream.
2019-07-08 11:32:10 +01:00
Hanno Becker 73f4cb126d Rename XXX_SINGLE_CIPHERSUITE -> XXX_CONF_SINGLE_CIPHERSUITE
This is in line with the other configurations options used
to hardcoded aspects of the SSL configuration.
2019-07-08 11:23:24 +01:00
Hanno Becker e02758c9c8 Remove ciphersuite from SSL session if single suite hardcoded
If MBEDTLS_SSL_SINGLE_CIPHERSUITE is enabled, the type

  mbedtls_ssl_ciphersuite_handle_t

is logically a boolean (concretely realized as `unsigned char`),
containing the invalid handle and the unique valid handle, which
represents the single enabled ciphersuite.

The SSL session structure mbedtls_ssl_session contains an instance
of mbedtls_ssl_ciphersuite_handle_t which is guaranteed to be valid,
and which is hence redundant in any two-valued implementation of
mbedtls_ssl_ciphersuite_handle_t.

This commit replaces read-uses of

  mbedtls_ssl_session::ciphersuite_info

by a getter functions which, and defines this getter function
either by just reading the field from the session structure
(in case MBEDTLS_SSL_SINGLE_CIPHERSUITE is disabled), or by
returning the single valid ciphersuite handle (in case
MBEDTLS_SSL_SINGLE_CIPHERSUITE is enabled) and removing the
field from mbedtls_ssl_session in this case.
2019-07-08 11:23:24 +01:00
Hanno Becker 6ace4657b6 Remove ciphersuite from SSL config if single suite hardcoded
If MBEDTLS_SSL_SINGLE_CIPHERSUITE is enabled, it overwrites
the runtime configuration of supported ciphersuites, which
includes both the configuration API and the fields which are
used to store the configuration. Both are therefore no longer
needed and should be removed for the benefit of code-size,
memory usage, and API clarity (no accidental hiccup of runtime
vs. compile-time configuration possible).

The configuration API mbedtls_ssl_conf_ciphersuites() has
already been removed in case MBEDTLS_SSL_SINGLE_CIPHERSUITE,
and this commit removes the field

  mbedtls_ssl_config::ciphersuite_list

which it updates.
2019-07-08 11:23:24 +01:00
Hanno Becker df64596733 Remove ciphersuite from handshake params if single suite hardcoded
If MBEDTLS_SSL_SINGLE_CIPHERSUITE is enabled, the type

  mbedtls_ssl_ciphersuite_handle_t

is logically a boolean (concretely realized as `unsigned char`),
containing the invalid handle and the unique valid handle, which
represents the single enabled ciphersuite.

The SSL handshake structure mbedtls_ssl_handshake_params contains
an instance of mbedtls_ssl_ciphersuite_handle_t which is guaranteed
to be valid, and which is hence redundant in any two-valued
implementation of mbedtls_ssl_ciphersuite_handle_t.

This commit replaces read-uses of

  mbedtls_ssl_handshake_params::ciphersuite_info

by a getter functions which, and defines this getter function
either by just reading the field from the handshake structure
(in case MBEDTLS_SSL_SINGLE_CIPHERSUITE is disabled), or by
returning the single valid ciphersuite handle (in case
MBEDTLS_SSL_SINGLE_CIPHERSUITE is enabled) and removing the
field from mbedtls_ssl_handshake_params in this case.
2019-07-08 11:23:24 +01:00
Hanno Becker 473f98f2e0 Introduce ciphersuite handle type
This commit introduces an internal zero-cost abstraction layer for
SSL ciphersuites: Instead of addressing ciphersuites via pointers
to instances of mbedtls_ssl_ciphersuite_t and accessing their fields
directly, this commit introduces an opaque type

  mbedtls_ssl_ciphersuite_handle_t,

and getter functions

  mbedtls_ssl_suite_get_xxx()

operating on ciphersuite handles.

The role of NULL is played by a new macro constant

  MBEDTLS_SSL_CIPHERSUITE_INVALID_HANDLE

which results of functions returning handles can be checked against.
(For example, when doing a lookup of a ciphersuite from a peer-provided
ciphersuite ID in the per's Hello message).

The getter functions have the validity of the handle as a precondition
and are undefined if the handle is invalid.

So far, there's only one implementation of this abstraction layer, namely

  mbedtls_ssl_ciphersuite_handle_t being mbedtls_ssl_ciphersuite_t const *

and

  getter functions being field accesses.

In subsequent commits, however, the abstraction layer will be useful
to save code in the situation where only a single ciphersuite is enabled.
2019-07-08 11:17:53 +01:00
Manuel Pégourié-Gonnard 5455afd74e
Merge pull request #599 from ARMmbed/baremetal-ec-preparation
[Baremetal] Avoid heap-allocation for client-supported elliptic curves
2019-07-05 14:16:41 +02:00
Hanno Becker d3b2fcb7c6 Don't store client-supported ECs in heap-allocated buffer
So far, the client-proposed list of elliptic curves was stored for the
duration of the entire handshake in a heap-allocated buffer referenced
from mbedtls_ssl_handshake_params::curves. It is used in the following
places:
1) When the server chooses a suitable ciphersuite, it checks that
   it has a certificate matching the ciphersuite; in particular, if
   the ciphersuite involves ECDHE, the server needs an EC certificate
   with a curve suitable for the client.
2) When performing the ECDHE key exchange, the server choose one
   curve among those proposed by the client which matches the server's
   own supported curve configuration.

This commit removes the hold back the entire client-side curve list
during the handshake, by performing (1) and (2) on during ClientHello
parsing, and in case of (2) only remembering the curve chosen for ECDHE
within mbedtls_ssl_handshake_params.
2019-07-04 12:41:08 +01:00
Hanno Becker 0ae6b244c8 Allow compile-time configuration of timer callbacks
Introduces
- MBEDTLS_SSL_CONF_SET_TIMER
- MBEDTLS_SSL_CONF_GET_TIMER
which allows to configure timer callbacks at compile-time.

Impact on code-size:

|  | GCC 8.2.1 | ARMC5 5.06 | ARMC6 6.12 |
| --- | --- | --- | --- |
| `libmbedtls.a` before | 23379 | 23981 | 26941 |
| `libmbedtls.a` after | 23351 | 23953 | 26869 |
| gain in Bytes | 28 | 28 | 72 |
2019-07-04 10:29:44 +01:00
Hanno Becker a58a896172 Allow compile-time configuration of I/O function pointers
Introduce the compile-time options
- MBEDTLS_SSL_CONF_RECV
- MBEDTLS_SSL_CONF_SEND
- MBEDTLS_SSL_CONF_RECV_TIMEOUT
which can be used to configure the callbacks for the underlying
transport at compile-time.

Code-size impact:

|  | GCC 8.2.1 | ARMC5 5.06 | ARMC6 6.12 |
| --- | --- | --- | --- |
| `libmbedtls.a` before | 23471 | 24077 | 27045 |
| `libmbedtls.a` before | 23379 | 23981 | 26941 |
| gain in Bytes | 92 | 96 | 104 |
2019-07-04 10:28:55 +01:00
Hanno Becker ece325c8dd Allow compile-time configuration of PRNG in SSL module
Introduces MBEDTLS_SSL_CONF_RNG to allow configuring the
RNG to be used by the SSL module at compile-time.

Impact on code-size:

|  | GCC 8.2.1 | ARMC5 5.06 | ARMC6 6.12 |
| --- | --- | --- | --- |
| `libmbedtls.a` before | 23535 | 24089 | 27103 |
| `libmbedtls.a` after | 23471 | 24077 | 27045 |
| gain in Bytes | 64 | 12 | 58 |
2019-07-04 10:27:41 +01:00
Manuel Pégourié-Gonnard b391766802 Fix unused variable that happened during merge
Fix an "unused variable" warning that happened in some configurations
(without EC, found by depend-pkalg.pl) and was not present in any parent PR
but only in the result of merging them: one of the PRs clarified the
distinction between `ret` and `verify_ret` and the other removed one
occurrence of using `ret`, and the conjunction of the two made `ret` unused in
some cases. Resolving by reducing the scope of that variable.
2019-07-03 11:24:24 +02:00
Manuel Pégourié-Gonnard de8869c529 Merge remote-tracking branch 'restricted/pr/608' into baremetal-proposed
* restricted/pr/608:
  programs: Make `make clean` clean all programs always
  ssl_tls: Enable Suite B with subset of ECP curves
  windows: Fix Release x64 configuration
  timing: Remove redundant include file
  net_sockets: Fix typo in net_would_block()
  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
  Update library to 2.16.2
  Use 'config.pl baremetal' in all.sh
  Clarify ChangeLog entry for fix to #1628
  Fix #2370, minor typos and spelling mistakes
  Add Changelog entry for clang test-ref-configs.pl fix
  Enable more compiler warnings in tests/Makefile
  Change file scoping of test helpers.function
2019-07-03 10:31:46 +02:00
Manuel Pégourié-Gonnard 44ba6b0d26 Merge remote-tracking branch 'restricted/pr/594' into baremetal-proposed
* restricted/pr/594:
  Adapt baremetal.h and baremetal.sh
  Don't incl. CAs in CertReq message in baremetal build
  Allow config'n of incl of CertificateReq CA list Y/N at compile-time
  Allow configuration of endpoint (cli/srv) at compile-time
  Allow configuration of read timeouts at compile-time
  Allow configuration of ConnectionID at compile-time
  Allow compile-time configuration of legacy renegotiation
  Allow compile-time configuration of authentication mode
  Allow compile-time configuration of DTLS badmac limit
  Allow compile-time configuration of DTLS anti replay
2019-07-03 10:22:28 +02:00
Manuel Pégourié-Gonnard 37261e6f6b Merge remote-tracking branch 'restricted/pr/601' into baremetal-proposed
* restricted/pr/601: (27 commits)
  Fix compile-time guard for optional field in struct
  Move code to reduce probability of conflicts
  Fix typos caught by check-names.sh
  Clarify conditions related to resumption in client
  Introduce getter function for renego_status
  Add getter function for handshake->resume
  Remove now-redundant code
  Remove cache callbacks from config on client
  Fix a few style issues
  Expand documentation of new options a bit
  Fix renaming oversight in documentation
  Remove backticks in doxygen in config.h
  Declare dependency on tickets for two ssl-opt.sh tests
  Exclude new negative options from config.pl full
  Restore config.h defaults
  Address review comments
  Fix ssl_cli resumption guards
  Fix check-files, check-names and check-generated-features
  Add test to all.sh
  Add changelog entry
  ...
2019-07-03 10:04:13 +02:00
Manuel Pégourié-Gonnard 417d2ce076 Merge remote-tracking branch 'restricted/pr/584' into baremetal-proposed
* restricted/pr/584: (140 commits)
  Remove superfluous new line in x509.c
  Add comment about X.509 name comparison of buffer with itself
  [Fixup] Add missing PK release call in Cert Verify parsing
  Fix guard controlling whether nested acquire calls are allowed
  Add X.509 CRT test for nested calls for CRT frame / PK acquire
  Don't return threading error on release()-without-acquire() calls
  Don't allow nested CRT acquire()-calls if MBEDTLS_X509_ALWAYS_FLUSH
  Make X.509 CRT cache reference counting unconditional
  Remove memory buffer alloc from i386 test in all.sh
  Don't mention pk_sign() in the context of public-key contexts
  Don't use assertion for failures of mbedtls_x509_crt_x_acquire()
  Fix copy pasta in x509_crt.h
  Reference copy-less versions of X.509 CRT frame/PK getters
  x509_crt.c: Add blank line to increase readability
  [FIXUP] Fix bug in ASN.1 traversal of silently ignored tag
  [FIXUP] Fix typo in declaration of mbedtls_x509_memcasecmp()
  Move signature-info extraction out of MBEDTLS_X509_REMOVE_INFO
  Fix certificate validity checking logic to work with !TIME_DATE
  Simplify X.509 CRT version check in UID parsing
  Remove unused variable warning in on-demand X.509 parsing
  ...
2019-07-03 10:03:45 +02:00
Hanno Becker c2cfdaa693 Allow config'n of incl of CertificateReq CA list Y/N at compile-time
Introduces MBEDTLS_SSL_CONF_CERT_REQ_CA_LIST which allows to configure
at compile-time whether a CA list should be included in the
CertificateRequest message sent by the server.

Impact on code-size:

|  | GCC 8.2.1 | ARMC5 5.06 | ARMC6 6.12 |
| --- | --- | --- | --- |
| `libmbedtls.a` before  | 23131 | 23805 | 26673 |
| `libmbedtls.a` after | 23099 | 23781 | 26639 |
| gain in Bytes | 32 | 24 | 34 |
2019-07-02 16:42:45 +01:00
Hanno Becker 2d9623f7d5 Allow configuration of endpoint (cli/srv) at compile-time
Introduces MBEDTLS_SSL_CONF_ENDPOINT to allow to choose between
server- or client-builds at compile-time.

Impact on code-size:

|  | GCC 8.2.1 | ARMC5 5.06 | ARMC6 6.12 |
| --- | --- | --- | --- |
| `libmbedtls.a` (client only) before  | 18355 | 18815 | 21485 |
| `libmbedtls.a` (client only) after | 18219 | 18683 | 21347 |
| gain in Bytes (client only) | 136 | 132 | 138 |
| `libmbedtls.a` (server only) before  | 18715 | 18987 | 21883 |
| `libmbedtls.a` (server only) after | 18595 | 18823 | 21717 |
| gain in Bytes (server only) | 120 | 164 | 166 |
2019-07-02 16:42:41 +01:00
Hanno Becker 1f835fa22b Allow configuration of read timeouts at compile-time
Introduces compile-time constants
- MBEDTLS_SSL_CONF_READ_TIMEOUT
- MBEDTLS_SSL_CONF_HS_TIMEOUT_MIN
- MBEDTLS_SSL_CONF_HS_TIMEOUT_MAX
which allow to configure the read timeouts and
minimum/maximum handshake timeout at compile time.

Impact on code-size:

|  | GCC 8.2.1 | ARMC5 5.06 | ARMC6 6.12 |
| --- | --- | --- | --- |
| `libmbedtls.a` before  | 23147 | 23781 | 26703 |
| `libmbedtls.a` after | 23131 | 23753 | 26673 |
| gain in Bytes | 16 | 28 | 30 |
2019-07-02 16:42:10 +01:00
Hanno Becker e0200dad63 Allow configuration of ConnectionID at compile-time
Introduces
- MBEDTLS_SSL_CONF_CID_LEN and
- MBEDTLS_SSL_CONF_IGNORE_UNEXPECTED_CID
to control
- the length of incoming CIDs
- the behaviour in receipt of unexpected CIDs
at compile-time.

Impact on code-size:

|  | GCC 82.1 | ARMC5 5.06 | ARMC6 6.12 |
| --- | --- | --- | --- |
| `libmbedtls.a` before | 23223 | 23865 | 26775 |
| `libmbedtls.a` after  | 23147 | 23781 | 26703 |
| gain in Bytes | 76 | 84 | 72 |
2019-07-02 16:41:35 +01:00
Hanno Becker b0b2b67568 Allow compile-time configuration of legacy renegotiation
Introduces MBEDTLS_SSL_CONF_ALLOW_LEGACY_RENEGOTIATION
allowing to configure enforcing secure renegotiation at
compile-time.

Impact on code-size:

|  | GCC | ARMC5 | ARMC6 |
| --- | --- | --- | --- |
| `libmbedtls.a` after  | 23379 | 23929 | 27727 |
| `libmbedtls.a` before | 23307 | 23865 | 27615 |
| gain in Bytes | 72 | 64 | 112 |
2019-07-02 16:41:34 +01:00
Hanno Becker acd4fc0ac9 Allow compile-time configuration of authentication mode
Introduces MBEDTLS_SSL_CONF_AUTHMODE to fix the authentication
mode (none, optional, mandatory) at compile-time.

Impact on code-size:

|  | GCC | ARMC5 | ARMC6 |
| --- | --- | --- | --- |
| `libmbedtls.a` before | 23487 | 24025 | 27885 |
| `libmbedtls.a` after  | 23379 | 23929 | 27727 |
| gain in Bytes | 108 | 96 | 157 |
2019-07-02 16:41:29 +01:00
Hanno Becker de67154658 Allow compile-time configuration of DTLS badmac limit
Introduces MBEDTLS_SSL_CONF_BADMAC_LIMIT to fix the maximum
number of records with bad MAC tolerated in DTLS at compile-time.

Impact on code-size:

|  | GCC | ARMC5 | ARMC6 |
| --- | --- | --- | --- |
| `libmbedtls.a` before  | 23511 | 24049 | 27903 |
| `libmbedtls.a` after | 23487 | 24025 | 27885 |
| gain in Bytes | 24 | 24 | 18 |
2019-07-02 16:40:50 +01:00
Manuel Pégourié-Gonnard 7b80c64de4 Fix compile-time guard for optional field in struct 2019-07-02 16:24:55 +02:00
Jarno Lamsa 29f2dd0a7b Address review comments 2019-07-02 15:12:29 +02:00
Jarno Lamsa 59bd12bf14 Add new config MBEDTLS_SSL_SESSION_RESUMPTION
Add a new configuration option MBEDTLS_SSL_SESSION_RESUMPTION
to enable/disable the session resumption feature including
ticket and cache based session resumption.
2019-07-02 15:12:29 +02:00
Jarno Lamsa 7be14065e2 Add config MBEDTLS_SSL_SESSION_CACHE
Add configuration option MBEDTLS_SSL_SESSION_CACHE to control
enabling/disabling of the cache based session resumption.
2019-07-02 15:12:29 +02:00
Hanno Becker abd929c89c Merge branch 'mbedtls-2.16' into baremetal-2.16-01_07_19 2019-07-01 11:25:42 +01:00
Hanno Becker 2224ccf390 Don't use assertion for failures of mbedtls_x509_crt_x_acquire()
These functions may afil in a regular run, e.g. due to an out of memory
error.
2019-06-28 14:48:31 +01:00
Hanno Becker c6d1c3ed1c Remove frame/pk parameter from mbedtls_x509_crt_xxx_release() 2019-06-25 09:07:16 +01:00
Hanno Becker 8c13ee615f Make use of CRT acquire/release in ssl_parse_certificate_verify()
Access the peer's PK through the PK acquire/release API only.

Care has to be taken not to accidentally overwrite the return
value `ret` from the CRT chain verification.
2019-06-25 09:06:26 +01:00
Hanno Becker 7f376f4ece Allow compile-time configuration of DTLS anti replay
Introduce MBEDTLS_SSL_CONF_ANTI_REPLAY to allow configuring
the use/nonuse of DTLS anti replay protection at compile-time.

Impact on code-size, measured with
> ./scripts/baremetal.sh --rom --gcc --armc5 --armc6

|  | GCC | ARMC5 | ARMC6 |
| --- | --- | --- | --- |
| `libmbedtls.a` before | 23559 | 24089 | 27921 |
| `libmbedtls.a` after  | 23511 | 24049 | 27903 |
| gain in Bytes | 48 | 40 | 18 |
2019-06-25 08:43:31 +01:00
Hanno Becker f765ce617f Remove ExtendedMS configuration API if hardcoded at compile-time
If the ExtendedMasterSecret extension is configured at compile-time
by setting MBEDTLS_SSL_CONF_EXTENDED_MASTER_SECRET and/or
MBEDTLS_SSL_CONF_ENFORCE_EXTENDED_MASTER_SECRET, the runtime
configuration APIs mbedtls_ssl_conf_extended_master_secret()
and mbedtls_ssl_conf_extended_master_secret_enforce() must
either be removed or modified to take no effect (or at most
check that the runtime value matches the hardcoded one, but
that would undermine the code-size benefits the hardcoding
is supposed to bring in the first place).

Previously, the API was kept but modified to have no effect.
While convenient for us because we don't have to adapt example
applications, this comes at the danger of users calling the runtime
configuration API, forgetting that the respective fields are
potentially already hardcoded at compile-time - and hence silently
using a configuration they don't intend to use.

This commit changes the approach to removing the configuration
API in case the respective field is hardcoded at compile-time,
and exemplifies it in the only case implemented so far, namely
the configuration of the ExtendedMasterSecret extension.

It adapts ssl_client2 and ssl_server2 by omitting the call to
the corresponding API if MBEDTLS_SSL_CONF_XXX are defined and
removing the command line parameters for the runtime configuration
of the ExtendedMasterSecret extension.
2019-06-25 08:42:20 +01:00
Hanno Becker a49ec56f51 Introduce getter function for extended_ms field in HS struct 2019-06-25 08:42:20 +01:00
Hanno Becker aabbb582eb Exemplify harcoding SSL config at compile-time in example of ExtMS
This commit is the first in a series demonstrating how code-size
can be reduced by hardcoding parts of the SSL configuration at
compile-time, focusing on the example of the configuration of
the ExtendedMasterSecret extension.

The flexibility of an SSL configuration defined a runtime vs.
compile-time is necessary for the use of Mbed TLS as a
dynamically linked library, but is undesirable in constrained
environments because it introduces the following overhead:
- Definition of SSL configuration API (code-size overhead)
  (and on the application-side: The API needs to be called)
- Additional fields in the SSL configuration (RAM overhead,
  and potentially code-size overhead if structures grow
  beyond immediate-offset bounds).
- Dereferencing is needed to obtain configuration settings.
- Code contains branches and potentially additional structure
  fields to distinguish between different configurations.

Considering the example of the ExtendedMasterSecret extension,
this instantiates as follows:
- mbedtls_ssl_conf_extended_master_secret() and
  mbedtls_ssl_conf_extended_master_secret_enforced()
  are introduced to configure the ExtendedMasterSecret extension.
- mbedtls_ssl_config contains bitflags `extended_ms` and
  `enforce_extended_master_secret` reflecting the runtime
  configuration of the ExtendedMasterSecret extension.
- Whenever we need to access these fields, we need a chain
  of dereferences `ssl->conf->extended_ms`.
- Determining whether Client/Server should write the
  ExtendedMasterSecret extension needs a branch
  depending on `extended_ms`, and the state of the
  ExtendedMasterSecret negotiation needs to be stored in a new
  handshake-local variable mbedtls_ssl_handshake_params::extended_ms.
  Finally (that's the point of ExtendedMasterSecret) key derivation
  depends on this handshake-local state of ExtendedMasterSecret.

All this is unnecessary if it is known at compile-time that the
ExtendedMasterSecret extension is used and enforced:
- No API calls are necessary because the configuration is fixed
  at compile-time.
- No SSL config fields are necessary because there are corresponding
  compile-time constants instead.
- Accordingly, no dereferences for field accesses are necessary,
  and these accesses can instead be replaced by the corresponding
  compile-time constants.
- Branches can be eliminated at compile-time because the compiler
  knows the configuration. Also, specifically for the ExtendedMasterSecret
  extension, the field `extended_ms` in the handshake structure
  is unnecessary, because we can fail immediately during the Hello-
  stage of the handshake if the ExtendedMasterSecret extension
  is not negotiated; accordingly, the non-ExtendedMS code-path
  can be eliminated from the key derivation logic.

A way needs to be found to allow fixing parts of the SSL configuration
at compile-time which removes this overhead in case it is used,
while at the same time maintaining readability and backwards
compatibility.

This commit proposes the following approach:

From the user perspective, for aspect of the SSL configuration
mbedtls_ssl_config that should be configurable at compile-time,
introduce a compile-time option MBEDTLS_SSL_CONF_FIELD_NAME.
If this option is not defined, the field is kept and configurable
at runtime as usual. If the option is defined, the field is logically
forced to the value of the option at compile time.

Internally, read-access to fields in the SSL configuration which are
configurable at compile-time gets replaced by new `static inline` getter
functions which evaluate to the corresponding field access or to the
constant MBEDTLS_SSL_CONF_FIELD_NAME, depending on whether the latter
is defined or not.

Write-access to fields which are configurable at compile-time needs
to be removed: Specifically, the corresponding API itself either
needs to be removed or replaced by a stub function without effect.
This commit takes the latter approach, which has the benefit of
not requiring any change on the example applications, but introducing
the risk of mismatching API calls and compile-time configuration,
in case a user doesn't correctly keep track of which parts of the
configuration have been fixed at compile-time, and which haven't.
Write-access for the purpose of setting defaults is simply omitted.
2019-06-25 08:42:20 +01:00
Manuel Pégourié-Gonnard 393338ca78
Merge pull request #586 from ARMmbed/remove_peer_crt_after_handshake_no_digest-baremetal
[Baremetal] Don't store peer CRT digest if renegotiation is disabled
2019-06-24 18:12:00 +02:00
Manuel Pégourié-Gonnard 79cf74a95f
Merge pull request #583 from ARMmbed/remove_peer_crt_after_handshake-baremetal
[Baremetal] Allow removal of peer certificate to reduce RAM usage
2019-06-24 18:11:46 +02:00
Manuel Pégourié-Gonnard cc3b7ccb04
Merge pull request #579 from Patater/bm-dont-use-non-existent-encrypt-then-mac
[Baremetal] ssl: Don't access non-existent encrypt_then_mac field
2019-06-24 18:06:53 +02:00
Jaeden Amero 7f132cc1a3 Merge remote-tracking branch 'origin/pr/2714' into mbedtls-2.16
* origin/pr/2714:
  programs: Make `make clean` clean all programs always
  ssl_tls: Enable Suite B with subset of ECP curves
  windows: Fix Release x64 configuration
  timing: Remove redundant include file
  net_sockets: Fix typo in net_would_block()
2019-06-21 16:00:52 +01:00
Jaeden Amero 16529b21fa 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 16:34:24 +01:00
Hanno Becker 5882dd0856 Remove CRT digest from SSL session if !RENEGO + !KEEP_PEER_CERT
If `MBEDTLS_SSL_KEEP_PEER_CERTIFICATE` is not set, `mbedtls_ssl_session`
contains the digest of the peer's certificate for the sole purpose of
detecting a CRT change on renegotiation. Hence, it is not needed if
renegotiation is disabled.

This commit removes the `peer_cert_digest` fields (and friends) from
`mbedtls_ssl_session` if
   `!MBEDTLS_SSL_KEEP_PEER_CERTIFICATE + !MBEDTLS_SSL_RENEGOTIATION`,
which is a sensible configuration for constrained devices.

Apart from straightforward replacements of
   `if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)`
by
   `if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE) && \
        defined(MBEDTLS_SSL_RENEGOTIATION)`,
there's one notable change: On the server-side, the CertificateVerify
parsing function is a no-op if the client hasn't sent a certificate.
So far, this was determined by either looking at the peer CRT or the
peer CRT digest in the SSL session structure (depending on the setting
of `MBEDTLS_SSL_KEEP_PEER_CERTIFICATE`), which now no longer works if
`MBEDTLS_SSL_KEEP_PEER_CERTIFICATE` is unset. Instead, this function
now checks whether the temporary copy of the peer's public key within
the handshake structure is initialized or not (which is also a
beneficial simplification in its own right, because the pubkey is
all the function needs anyway).
2019-06-19 16:56:51 +01:00
Hanno Becker 0528f82fa9 Clarify documentation of serialized session format 2019-06-19 14:59:42 +01:00
Hanno Becker 17daaa5cc6 Move return statement in ssl_srv_check_client_no_crt_notification
The previous placing of the return statement made it look like there
are configurations for which no return statement is emitted; while
that's not true (if this function is used, at least some version of
TLS must be enabled), it's still clearer to move the failing return
statement to outside of all preprocessor guards.
2019-06-19 14:59:42 +01:00
Hanno Becker 2326d20361 Validate consistency of certificate hash type and length in session 2019-06-19 14:59:42 +01:00
Hanno Becker fd5dc8ae07 Fix unused variable warning in ssl_parse_certificate_coordinate()
This was triggered in client-only builds.
2019-06-19 14:59:42 +01:00
Hanno Becker 42de8f8a42 Fix typo in documentation of ssl_parse_certificate_chain() 2019-06-19 14:59:41 +01:00
Hanno Becker 9d64b789cf Set peer CRT length only after successful allocation 2019-06-19 10:26:50 +01:00
Hanno Becker 257ef65d94 Remove question in comment about verify flags on cli vs. server 2019-06-19 10:26:50 +01:00
Hanno Becker 34106f6ae2 Free peer CRT chain immediately after verifying it
If we don't need to store the peer's CRT chain permanently, we may
free it immediately after verifying it. Moreover, since we parse the
CRT chain in-place from the input buffer in this case, pointers from
the CRT structure remain valid after freeing the structure, and we
use that to extract the digest and pubkey from the CRT after freeing
the structure.
2019-06-19 10:26:50 +01:00
Hanno Becker 0cc7af5be5 Parse peer's CRT chain in-place from the input buffer 2019-06-19 10:26:50 +01:00
Hanno Becker 17572473c6 Correct compile-time guards for ssl_clear_peer_cert()
It is used in `mbedtls_ssl_session_free()` under
`MBEDTLS_X509_CRT_PARSE_C`, but defined only if
`MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED`.

Issue #2422 tracks the use of
`MBEDTLS_KEY_EXCHANGE__WITH_CERT_ENABLED` instead of
`MBEDTLS_X509_CRT_PARSE_C` for code and fields
related to CRT-based ciphersuites.
2019-06-19 10:26:50 +01:00
Hanno Becker bfab9dfea1 Guard mbedtls_ssl_get_peer_cert() by new compile-time option 2019-06-19 10:26:17 +01:00
Hanno Becker 81d11aa640 Adapt mbedtls_ssl_parse_certificate() to removal of peer_cert field 2019-06-19 10:25:02 +01:00
Hanno Becker 5062897507 Adapt ssl_clear_peer_cert() to removal of peer_cert field 2019-06-19 10:25:02 +01:00
Hanno Becker d5258faa29 Adapt mbedtls_ssl_session_copy() to removal of peer_cert field 2019-06-19 10:25:02 +01:00
Hanno Becker cf291d63dd Make a copy of peer's raw public key after verifying its CRT chain
This commit modifies `mbedtls_ssl_parse_certificate()` to store a
copy of the peer's public key after parsing and verifying the peer's
CRT chain.

So far, this leads to heavy memory duplication: We have the CRT chain
in the I/O buffer, then parse (and, thereby, copy) it to a
`mbedtls_x509_crt` structure, and then make another copy of the
peer's public key, plus the overhead from the MPI and ECP structures.

This inefficiency will soon go away to a significant extend, because:
- Another PR adds functionality to parse CRTs without taking
  ownership of the input buffers. Applying this here will allow
  parsing and verifying the peer's chain without making an additional
  raw copy. The overhead reduces to the size of `mbedtls_x509_crt`,
  the public key, and the DN structures referenced in the CRT.
- Once copyless parsing is in place and the removal of the peer CRT
  is fully implemented, we can extract the public key bounds from
  the parsed certificate and then free the entire chain before
  parsing the public key again. This means that we never store
  the parsed public key twice at the same time.
2019-06-19 10:25:02 +01:00
Hanno Becker 3bf8cdf2f8 Add field for peer's raw public key to TLS handshake param structure
When removing the (session-local) copy of the peer's CRT chain, we must
keep a handshake-local copy of the peer's public key, as (naturally) every
key exchange will make use of that public key at some point to verify that
the peer actually owns the corresponding private key (e.g., verify signatures
from ServerKeyExchange or CertificateVerify, or encrypt a PMS in a RSA-based
exchange, or extract static (EC)DH parameters).

This commit adds a PK context field `peer_pubkey` to the handshake parameter
structure `mbedtls_handshake_params_init()` and adapts the init and free
functions accordingly. It does not yet make actual use of the new field.
2019-06-19 10:25:01 +01:00
Hanno Becker 2e6d34761f Remove peer CRT from mbedtls_ssl_session if !KEEP_PEER_CERT 2019-06-19 10:25:01 +01:00
Hanno Becker 4a2f8e584f Add peer CRT digest to session tickets
This commit changes the format of session tickets to include
the digest of the peer's CRT if MBEDTLS_SSL_KEEP_PEER_CERTIFICATE
is disabled.

This commit does not yet remove the peer CRT itself.
2019-06-19 10:25:01 +01:00
Hanno Becker e4aeb76a2c Parse and verify peer CRT chain in local variable
`mbedtls_ssl_parse_certificate()` parses the peer's certificate chain
directly into the `peer_cert` field of the `mbedtls_ssl_session`
structure being established. To allow to optionally remove this field
from the session structure, this commit changes this to parse the peer's
chain into a local variable instead first, which can then either be freed
after CRT verification - in case the chain should not be stored - or
mapped to the `peer_cert` if it should be kept. For now, only the latter
is implemented.
2019-06-19 10:25:01 +01:00
Hanno Becker df75938b84 Mitigate triple handshake attack by comparing digests only
This paves the way for the removal of the peer CRT chain from
`mbedtls_ssl_session`.
2019-06-19 10:25:01 +01:00
Hanno Becker 3008d2869f Compute digest of peer's end-CRT in mbedtls_ssl_parse_certificate() 2019-06-19 10:25:01 +01:00
Hanno Becker 9fb6e2e203 Extend mbedtls_ssl_session by buffer holding peer CRT digest 2019-06-19 10:25:01 +01:00
Hanno Becker 58fccf2f62 Give ssl_session_copy() external linkage
A subsequent commit will need this function in the session ticket
and session cache implementations. As the latter are server-side,
this commit also removes the MBEDTLS_SSL_CLI_C guard.

For now, the function is declared in ssl_internal.h and hence not
part of the public API.
2019-06-19 10:25:01 +01:00
Hanno Becker 35e41771fe Allow passing any X.509 CRT chain to ssl_parse_certificate_chain()
This commit modifies the helper `ssl_parse_certificate_chain()` to
accep any target X.509 CRT chain instead of hardcoding it to
`session_negotiate->peer_cert`. This increases modularity and paves
the way towards removing `mbedtls_ssl_session::peer_cert`.
2019-06-19 10:25:01 +01:00
Hanno Becker 3cf5061091 Introduce helper function for peer CRT chain verification 2019-06-19 10:25:01 +01:00
Hanno Becker a7c1df6321 Don't progress TLS state machine on peer CRT chain parsing error 2019-06-19 10:25:01 +01:00
Hanno Becker 6b9a6f3f37 Add helper function to check whether a CRT msg is expected
This commit adds a helper function `ssl_parse_certificate_coordinate()`
which checks whether a `Certificate` message is expected from the peer.

The logic is the following:
- For ciphersuites which don't use server-side CRTs, no Certificate
  message is expected (neither for the server, nor the client).
- On the server, no client certificate is expected in the following cases:
  * The server server didn't request a Certificate, which is controlled
    by the `authmode` setting.
  * A RSA-PSK suite is used; this is the only suite using server CRTs
    but not allowing client-side authentication.
2019-06-19 10:25:01 +01:00
Hanno Becker 5097cba93c Introduce helper function to determine whether suite uses server CRT
This commit introduces a static helper function

   `mbedtls_ssl_ciphersuite_uses_srv_cert()`

which determines whether a ciphersuite may make use of server-side CRTs.

This function is in turn uses in `mbedtls_ssl_parse_certificate()` to
skip certificate parsing for ciphersuites which don't involve CRTs.

Note: Ciphersuites not using server-side CRTs don't allow client-side CRTs
either, so it is safe to guard `mbedtls_ssl_{parse/write}_certificate()`
this way.

Note: Previously, the code uses a positive check over the suites

- MBEDTLS_KEY_EXCHANGE_PSK
- MBEDTLS_KEY_EXCHANGE_DHE_PSK
- MBEDTLS_KEY_EXCHANGE_ECDHE_PSK
- MBEDTLS_KEY_EXCHANGE_ECJPAKE,

while now, it uses a negative check over `mbedtls_ssl_ciphersuite_uses_srv_cert()`,
which checks for the suites

- MBEDTLS_KEY_EXCHANGE_RSA
- MBEDTLS_KEY_EXCHANGE_RSA_PSK
- MBEDTLS_KEY_EXCHANGE_DHE_RSA
- MBEDTLS_KEY_EXCHANGE_ECDH_RSA
- MBEDTLS_KEY_EXCHANGE_ECDHE_RSA
- MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA
- MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA

This is equivalent since, together, those are all ciphersuites.
Quoting ssl_ciphersuites.h:

```
typedef enum {
    MBEDTLS_KEY_EXCHANGE_NONE = 0,
    MBEDTLS_KEY_EXCHANGE_RSA,
    MBEDTLS_KEY_EXCHANGE_DHE_RSA,
    MBEDTLS_KEY_EXCHANGE_ECDHE_RSA,
    MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA,
    MBEDTLS_KEY_EXCHANGE_PSK,
    MBEDTLS_KEY_EXCHANGE_DHE_PSK,
    MBEDTLS_KEY_EXCHANGE_RSA_PSK,
    MBEDTLS_KEY_EXCHANGE_ECDHE_PSK,
    MBEDTLS_KEY_EXCHANGE_ECDH_RSA,
    MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA,
    MBEDTLS_KEY_EXCHANGE_ECJPAKE,
} mbedtls_key_exchange_type_t;
```
2019-06-19 10:25:01 +01:00
Hanno Becker b71e90acc5 Use helper macro to detect whether some ciphersuite uses CRTs 2019-06-19 10:25:01 +01:00
Hanno Becker 613d490bf1 Unify state machine update in mbedtls_ssl_parse_certificate()
The handler `mbedtls_ssl_parse_certificate()` for incoming `Certificate`
messages contains many branches updating the handshake state. For easier
reasoning about state evolution, this commit introduces a single code-path
updating the state machine at the end of `mbedtls_ssl_parse_certificate()`.
2019-06-19 10:25:01 +01:00
Hanno Becker a46c287796 Clear peer's CRT chain outside before parsing new one
If an attempt for session resumption fails, the `session_negotiate` structure
might be partially filled, and in particular already contain a peer certificate
structure. This certificate structure needs to be freed before parsing the
certificate sent in the `Certificate` message.

This commit moves the code-path taking care of this from the helper
function `ssl_parse_certificate_chain()`, whose purpose should be parsing
only, to the top-level handler `mbedtls_ssl_parse_certificate()`.

The fact that we don't know the state of `ssl->session_negotiate` after
a failed attempt for session resumption is undesirable, and a separate
issue #2414 has been opened to improve on this.
2019-06-19 10:25:01 +01:00
Hanno Becker b8a085744f Introduce helper to check for no-CRT notification from client
This commit introduces a server-side static helper function
`ssl_srv_check_client_no_crt_notification()`, which checks if
the message we received during the incoming certificate state
notifies the server of the lack of certificate on the client.

For SSLv3, such a notification comes as a specific alert,
while for all other TLS versions, it comes as a `Certificate`
handshake message with an empty CRT list.
2019-06-19 10:25:01 +01:00
Hanno Becker 8794fd927c Introduce CRT counter to CRT chain parsing function
So far, we've used the `peer_cert` pointer to detect whether
we're parsing the first CRT, but that will soon be removed
if `MBEDTLS_SSL_KEEP_PEER_CERTIFICATE` is unset.
2019-06-19 10:25:01 +01:00
Hanno Becker 22141593e1 Introduce helper function to clear peer CRT from session structure
This commit introduces a helper function `ssl_clear_peer_cert()`
which frees all data related to the peer's certificate from an
`mbedtls_ssl_session` structure. Currently, this is the peer's
certificate itself, while eventually, it'll be its digest only.
2019-06-19 10:25:01 +01:00
Hanno Becker 933b9fc815 Break overly long line in definition of mbedtls_ssl_get_session() 2019-06-19 10:25:01 +01:00
Hanno Becker 1332f35a4e Don't reuse CRT from initial handshake during renegotiation
After mitigating the 'triple handshake attack' by checking that
the peer's end-CRT didn't change during renegotation, the current
code avoids re-parsing the CRT by moving the CRT-pointer from the
old session to the new one. While efficient, this will no longer
work once only the hash of the peer's CRT is stored beyond the
handshake.

This commit removes the code-path moving the old CRT, and instead
frees the entire peer CRT chain from the initial handshake as soon
as the 'triple handshake attack' protection has completed.
2019-06-19 10:25:01 +01:00