- The validity of the input and output parameters is checked by
parameter validation.
- A PRNG is required in public mode only (even though it's also
recommended in private mode), so move the check to the
corresponding branch.
The check was already done later when calling ECB, (as evidenced by the tests
passing, which have a call with data_unit set to NULL), but it's more readable
to have it here too, and more helpful when debugging.
The function called through the macro MBEDTLS_PARAM_FAILED() must be supplied by
users and makes no sense as a library function, apart from debug and test.
Function calls to alternative implementations have to follow certain
rules in order to preserve correct functionality. To avoid accidentally
breaking these rules we state them explicitly in the ECP module for
ourselves and every contributor to see.
We initialized the ECC hardware before calling
mbedtls_ecp_mul_shortcuts(). This in turn calls
mbedtls_ecp_mul_restartable(), which initializes and frees the hardware
too. This issue has been introduced by recent changes and caused some
accelerators to hang.
We move the initialization after the mbedtle_ecp_mul_shortcuts() calls
to avoid double initialization.
The SSL module accesses ECDH context members directly. This can't work
with the new context, where we can't make any assumption about the
implementation of the context.
This commit makes use of the new functions to avoid accessing ECDH
members directly. The only members that are still accessed directly are
the group ID and the point format and they are independent from the
implementation.
The SSL module accesses ECDH context members directly to print debug
information. This can't work with the new context, where we can't make
assumptions about the implementation of the context. This commit adds
new debug functions to complete the encapsulation of the ECDH context
and work around the problem.
The functionality from public API functions are moved to
`xxx_internal()` functions. The public API functions are modified to do
basic parameter validation and dispatch the call to the right
implementation.
There is no intended change in behaviour when
`MBEDTLS_ECDH_LEGACY_CONTEXT` is enabled.
In the future we want to support alternative ECDH implementations. We
can't make assumptions about the structure of the context they might
use, and therefore shouldn't access the members of
`mbedtls_ecdh_context`.
Currently the lifecycle of the context can't be done without direct
manipulation. This commit adds `mbedtls_ecdh_setup()` to complete
covering the context lifecycle with functions.
`mbedtls_ecp_tls_read_group()` both parses the group ID and loads the
group into the structure provided. We want to support alternative
implementations of ECDH in the future and for that we need to parse the
group ID without populating an `mbedtls_ecp_group` structure (because
alternative implementations might not use that).
This commit moves the part that parses the group ID to a new function.
There is no need to test the new function directly, because the tests
for `mbedtls_ecp_tls_read_group()` are already implicitly testing it.
There is no intended change in behaviour in this commit.
Refactor `mpi_write_hlp()` to not be recursive, to fix stack overflows.
Iterate over the `mbedtls_mpi` division of the radix requested,
until it is zero. Each iteration, put the residue in the next LSB
of the output buffer. Fixes#2190
Refactor mbedtls_ctr_drbg_update_seed_file and
mbedtls_hmac_drbg_update_seed_file to make the error logic clearer.
The new code does not use fseek, so it works with non-seekable files.
Return early from mbedtls_pk_write_pubkey_der - public opaque key
exporting is expected to contain all of the needed data, therefore it shouldn't
be written again.
There is a probability that r will be encoded as 31 or less bytes in DER,
so additional padding is added in such case.
Added a signature-part extraction function to tidy up the code further.
Reasons:
- For the first release, we attempt to support TLS-1.2 only,
- At least TLS-1.0 is known to not work at the moment, as
for CBC ciphersuites the code in mbedtls_ssl_decrypt_buf()
and mbedtls_ssl_encrypt_buf() assumes that mbedtls_cipher_crypt()
updates the structure field for the IV in the cipher context,
which the PSA-based implementation currently doesn't.
This commit modifies the default SSL ticket implementation
from `library/ssl_ticket.c` to use PSA-based cipher context
for ticket creation and parsing.
As in mbedtls_ssl_derive_keys() adapted in an earlier commit,
we allow fallback to the ordinary mbedtls_cipher_setup()
if the provided cipher is not known. We do this even though
we always call mbedtls_ssl_ticket_setup() with AES-GCM
in our own code since this function is public and might
be used with other ciphers by users.
This commit changes the code path in mbedtls_ssl_derive_keys()
responsible for setting up record protection cipher contexts
to attempt to use the new API mbedtls_cipher_setup_psa() in
case MBEDTLS_USE_PSA_CRYPTO is set.
For that, the AEAD tag length must be provided, which is already
computed earlier in mbedtls_ssl_derive_keys() and only needs to be
stored a function scope to be available for mbedtls_cipher_setup_psa().
If mbedtls_cipher_setup_psa() fails cleanly indicating that the
requested cipher is not supported in PSA, we fall through to
the default setup using mbedtls_cipher_setup(). However, we print
a debug message in this case, to allow catching the fallthrough in
tests where we know we're using a cipher which should be supported
by PSA.
mbedtls_cipher_setup_psa() should return
MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE when the requested
cipher is not supported by PSA, so that the caller can
try the original mbedtls_cipher_setup() instead.
The previous version of mbedtls_cipher_setup_psa(), however,
only attempted to translate the cipher mode (GCM, CCM, CBC,
ChaChaPoly, Stream), but didn't consider the underlying
cipher primitive. Hence, it wouldn't fail when attempting
to setup a cipher context for, say, 3DES-CBC, where CBC
is currently supported by PSA but 3DES isn't.
This commit adds a check to mbedtls_cipher_setup_psa()
for whether the requested cipher primitive is available
in the underlying PSA Crypto implementation, and fails
cleanly with MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE if
it is isn't.
For AEAD ciphers, the information contained in mbedtls_cipher_info
is not enough to deduce a PSA algorithm value of type psa_algorithm_t.
This is because mbedtls_cipher_info doesn't contain the AEAD tag
length, while values of type psa_algorithm_t do.
This commit adds the AEAD tag length as a separate parameter
to mbedtls_cipher_setup_psa(). For Non-AEAD ciphers, the value
must be 0.
This approach is preferred over passing psa_algorithm_t directly
in order to keep the changes in existing code using the cipher layer
small.
Mbed TLS cipher layer allows usage of keys for other purposes
than indicated in the `operation` parameter of `mbedtls_cipher_setkey()`.
The semantics of the PSA Crypto API, in contrast, checks key
usage against the key policy.
As a remedy, this commit modifies the PSA key slot setup to
always allow both encryption and decryption.
This commit implements the internal key slot management performed
by PSA-based cipher contexts. Specifically, `mbedtls_cipher_setkey()`
wraps the provided raw key material into a key slot, and
`mbedtls_cipher_free()` destroys that key slot.
This field determines whether a cipher context should
use an external implementation of the PSA Crypto API for
cryptographic operations, or Mbed TLS' own crypto library.
The commit also adds dummy implementations for the cipher API.
It's better for names in the API to describe the "what" (opaque keys) rather
than the "how" (using PSA), at least since we don't intend to have multiple
function doing the same "what" in different ways in the foreseeable future.
Unfortunately the can_do wrapper does not receive the key context as an
argument, so it cannot check psa_get_key_information(). Later we might want to
change our internal structures to fix this, but for now we'll just restrict
opaque PSA keys to be ECDSA keypairs, as this is the only thing we need for
now. It also simplifies testing a bit (no need to test each key type).
The code maintains the invariant that raw and opaque PSKs are never
configured simultaneously, so strictly speaking `ssl_conf_remove_psk()`
need not consider clearing the raw PSK if it has already cleared an
opaque one - and previously, it didn't. However, it doesn't come at
any cost to keep this check as a safe-guard to future unforeseen
situations where opaque and raw PSKs _are_ both present.
In multiple places, it occurrs as the fixed length of
the master secret, so use a constant with a descriptive
name instead. This is reinforced by the fact the some
further occurrences of '48' are semantically different.
Using finer grained control over include directories will allow differnt
targets to use different include files. This will be useful when the
`crypto` subcomponent wants to use its own include files instead of or in
addition to the top level ones.
In mbedtls_mpi_write_binary, avoid leaking the size of the number
through timing or branches, if possible. More precisely, if the number
fits in the output buffer based on its allocated size, the new code's
trace doesn't depend on the value of the number.
Deprecate the module-specific XXX_HW_ACCEL_FAILED and
XXX_FEATURE_UNAVAILABLE errors, as alternative implementations should now
return `MBEDTLS_ERR_PLATFORM_HW_FAILED` and
`MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED`.
ssl_write_handshake_msg() includes the assertion that
`ssl->handshake != NULL` when handling a record which is
(a) a handshake message, and NOT
(b) a HelloRequest.
However, it later calls `ssl_append_flight()` for any
record different from a HelloRequest handshake record,
that is, records satisfying !(a) || !(b), instead of
(a) && !(b) as covered by the assertion (specifically,
CCS or Alert records).
Since `ssl_append_flight()` assumes that `ssl->handshake != NULL`,
this rightfully triggers static analyzer warnings.
This commit expands the scope of the assertion to check
that `ssl->handshake != NULL` for any record which is not
a HelloRequest.
Revert changes for checking whether `MBEDTLS_ECP_RESTARTABLE`
is defined, since it broke the CI. The context is used whether the
restartable feature is defined or not.
1. Checge to check for `MBEDTLS_ECP_RESTARTABLE` for all definitions
of `rs_ctx`.
2. Remove checks for `_ALT` when using `rs_ctx` as they cannot coexist
with the Restartable configuration.
Previously, when checking whether a CRT was revoked through
one of the configured CRLs, the library would only consider
those CRLs whose `issuer` field binary-matches the `subject`
field of the CA that has issued the CRT in question. If those
fields were not binary equivalent, the corresponding CRL was
discarded.
This is not in line with RFC 5280, which demands that the
comparison should be format- and case-insensitive. For example:
- If the same string is once encoded as a `PrintableString` and
another time as a `UTF8String`, they should compare equal.
- If two strings differ only in their choice of upper and lower case
letters, they should compare equal.
This commit fixes this by using the dedicated x509_name_cmp()
function to compare the CRL issuer with the CA subject.
Fixes#1784.
library/certs.c provides some hardcoded certificates that
are used e.g. by the test applications ssl_server2, ssl_client2
in case no certificates are provided on the command line.
The certificates used are from the tests/data_files folder
and have been updated in the latest commits. This commit
updates their copies in certs.c. It also adds comments
indicating the files from which the data is taken, in
order to ease update in the future.
Previous commits have added or modified build instructions for
server1*, server2*, server5*, test-ca*, cli-rsa* in the Makefile
tests/data_files/Makefile, or the apps they invoke have been changed.
This commit regenerates those files to make sure they are in match with
the build instructions.
Previously, when checking whether a CRT was revoked through
one of the configured CRLs, the library would only consider
those CRLs whose `issuer` field binary-matches the `subject`
field of the CA that has issued the CRT in question. If those
fields were not binary equivalent, the corresponding CRL was
discarded.
This is not in line with RFC 5280, which demands that the
comparison should be format- and case-insensitive. For example:
- If the same string is once encoded as a `PrintableString` and
another time as a `UTF8String`, they should compare equal.
- If two strings differ only in their choice of upper and lower case
letters, they should compare equal.
This commit fixes this by using the dedicated x509_name_cmp()
function to compare the CRL issuer with the CA subject.
Fixes#1784.
Return the condition compilation flags surrounding
`mbedtls_ecdh_compute_shared()`, `mbedtls_ecdh_gen_public()`,
`mbedtls_ecdsa_sign()` and `mbedtls_ecdsa_verify()` that were accidentally
removed in a previous merge.
Resolves#2163
This commit modifies a bounds check in `mbedtls_ecp_check_budget()` to
be correct even if the requested number of ECC operations would overflow
the operation counter.
Use `( x >> y ) & z` instead of `x >> y & z`. Both are equivalent
by operator precedence, but the former is more readable and the
commonly used idiom in the library.
Correct a typo in an AES XTS implementation comment where the relevant
NIST standard was incorrectly referred to as NIST 80-38E instead of NIST
800-38E.
It is inaccurate to call a data unit a "sector". A disk sector is a
common use case for the data unit, but there exist other types of data
units that are not sectors.
It turns out that in some environments MinGW esposes a non-conforming
(v)snprintf behavior despite the tests against the MSVC runtime pass.
Therefore it has been included in the "non-conforming" scope alongide
older MSVC rungime environments.
This commit fixes issue #1212 related to platform-specific entropy
polling in an syscall-emulated environment.
Previously, the implementation of the entropy gathering function
`mbedtls_platform_entropy_poll()` for linux machines used the
following logic to determine how to obtain entropy from the kernel:
1. If the getrandom() system call identifier SYS_getrandom is present and
the kernel version is 3.17 or higher, use syscall( SYS_getrandom, ... )
2. Otherwise, fall back to reading from /dev/random.
There are two issues with this:
1. Portability:
When cross-compiling the code for a different
architecture and running it through system call
emulation in qemu, qemu reports the host kernel
version through uname but, as of v.2.5.0,
doesn't support emulating the getrandom() syscall.
This leads to `mbedtls_platform_entropy_poll()`
failing even though reading from /dev/random would
have worked.
2. Style:
Extracting the linux kernel version from
the output of `uname` is slightly tedious.
This commit fixes both by implementing the suggestion in #1212:
- It removes the kernel-version detection through uname().
- Instead, it checks whether `syscall( SYS_getrandom, ... )`
fails with errno set to ENOSYS indicating an unknown system call.
If so, it falls through to trying to read from /dev/random.
Fixes#1212.
This commit changes the behavior of the record decryption routine
`ssl_decrypt_buf()` in the following situation:
1. A CBC ciphersuite with Encrypt-then-MAC is used.
2. A record with valid MAC but invalid CBC padding is received.
In this situation, the previous code would not raise and error but
instead forward the decrypted packet, including the wrong padding,
to the user.
This commit changes this behavior to return the error
MBEDTLS_ERR_SSL_INVALID_MAC instead.
While erroneous, the previous behavior does not constitute a
security flaw since it can only happen for properly authenticated
records, that is, if the peer makes a mistake while preparing the
padded plaintext.
This commit duplicates the public function mbedtls_asn1_find_named_data()
defined in library/asn1parse.c within library/asn1write.c in order to
avoid a dependency of the ASN.1 writing module on the ASN.1 parsing module.
The duplication is unproblematic from a semantic and an efficiency
perspective becasue it is just a short list traversal that doesn't
actually do any ASN.1 parsing.
Previously, mbedtls_pkcs5_pbes2() was unconditionally declared
in `pkcs5.h` but defined as a stub returning
`MBEDTLS_ERR_PKCS5_FEATURE_UNAVAILABLE` in case
MBEDTLS_ASN1_PARSE_C was not defined.
In line with the previous commits, this commit removes declaration
and definition from both `pkcs5.h` and `pkcs5.c` in case
MBEDTLS_ASN1_PARSE_C is not defined.
Our API makes no guarantee that you can use a context after free()ing it
without re-init()ing it first, so better not give the wrong impression that we
do, while it's not policy and the rest of the code might not allow it.
Rename the PLATFORM HW error, to avoid ABI breakage with Mbed OS.
The value changed as well, as previous value was not in the range of
Mbed TLS low level error codes.
* development:
ssl-opt.sh: change expected output for large srv packet test with SSLv3
Adapt ChangeLog
Fix bug in SSL ticket implementation removing keys of age < 1s
ssl-opt.sh: Add DTLS session resumption tests
Add ChangeLog entry
Fix typo
Fix hmac_drbg failure in benchmark, with threading
Remove trailing whitespace
Remove trailing whitespace
ssl_server2: add buffer overhead for a termination character
Add missing large and small packet tests for ssl_server2
Added buffer_size and response_size options for ssl-server2. Added appropriate tests.
Solving a conflict in tests/ssl-opt.sh: two set of tests were added at the
same place (just after large packets):
- restartable ECC tests (in this branch)
- server-side large packets (in development)
Resolution was to move the ECC tests after the newly added server large packet
ones.
The code assumed that `int x = - (unsigned) u` with 0 <= u < INT_MAX
sets `x` to the negative of u, but actually this calculates
(UINT_MAX - u) and then converts this value to int, which overflows.
Cast to int before applying the unary minus operator to guarantee the
desired behavior.
The code was making two unsequenced reads from volatile locations.
This is undefined behavior. It was probably harmless because we didn't
care in what order the reads happened and the reads were from ordinary
memory, but UB is UB and IAR8 complained.
This commit ensures that buffers holding fragmented or
future handshake messages get zeroized before they are
freed when the respective handshake message is no longer
needed. Previously, the handshake message content would
leak on the heap.
Context: This commit makes a change to mbedtls_pk_parse_key() which
is responsible for parsing of private keys. The function doesn't know
the key format in advance (PEM vs. DER, encrypted vs. unencrypted) and
tries them one by one, resetting the PK context in between.
Issue: The previous code resets the PK context through a call to
mbedtls_pk_free() along, lacking the accompanying mbedtls_pk_init()
call. Practically, this is not an issue because functionally
mbedtls_pk_free() + mbedtls_pk_init() is equivalent to mbedtls_pk_free()
with the current implementation of these functions, but strictly
speaking it's nonetheless a violation of the API semantics according
to which xxx_free() functions leave a context in uninitialized state.
(yet not entirely random, because xxx_free() functions must be idempotent,
so they cannot just fill the context they operate on with garbage).
Change: The commit adds calls to mbedtls_pk_init() after those calls
to mbedtls_pk_free() within mbedtls_pk_parse_key() after which the
PK context might still be used.
This commit removes the definition of the API function
`mbedtls_platform_set_calloc_free()`
from `library/platform.c` in case the macros
`MBEDTLS_PLATFORM_CALLOC_MACRO`
`MBEDTLS_PLATFORM_FREE_MACRO`
for compile time configuration of calloc/free are set.
This is in line with the corresponding header `mbedtls/platform.h`
which declares `mbedtls_platform_set_calloc_free()` only if
`MBEDTLS_PLATFORM_{CALLOC/FREE}_MACRO` are not defined.
Fixes#1642.
The previous code triggered a compiler warning because of a comparison
of a signed and an unsigned integer.
The conversion is safe because `len` is representable by 16-bits,
hence smaller than the maximum integer.
When a random number is generated for the Miller-Rabin primality test,
if the bit length of the random number is larger than the number being
tested, the random number is shifted right to have the same bit length.
This introduces bias, as the random number is now guaranteed to be
larger than 2^(bit length-1).
Changing this to instead zero all bits higher than the tested numbers
bit length will remove this bias and keep the random number being
uniformly generated.
When using a primality testing function the tolerable error rate depends
on the scheme in question, the required security strength and wether it
is used for key generation or parameter validation. To support all use
cases we need more flexibility than what the old API provides.
The input distribution to primality testing functions is completely
different when used for generating primes and when for validating
primes. The constants used in the library are geared towards the prime
generation use case and are weak when used for validation. (Maliciously
constructed composite numbers can pass the test with high probability)
The mbedtls_mpi_is_prime() function is in the public API and although it
is not documented, it is reasonable to assume that the primary use case
is validating primes. The RSA module too uses it for validating key
material.
The FIPS 186-4 RSA key generation prescribes lower failure probability
in primality testing and this makes key generation slower. We enable the
caller to decide between compliance/security and performance.
This python script calculates the base two logarithm of the formulas in
HAC Fact 4.48 and was used to determine the breakpoints and number of
rounds:
def mrpkt_log_2(k, t):
if t <= k/9.0:
return 3*math.log(k,2)/2+t-math.log(t,2)/2+4-2*math.sqrt(t*k)
elif t <= k/4.0:
c1 = math.log(7.0*k/20,2)-5*t
c2 = math.log(1/7.0,2)+15*math.log(k,2)/4.0-k/2.0-2*t
c3 = math.log(12*k,2)-k/4.0-3*t
return max(c1, c2, c3)
else:
return math.log(1/7.0)+15*math.log(k,2)/4.0-k/2.0-2*t
In the previous bounds check `(*p) > end - len`, the computation
of `end - len` might underflow if `end` is within the first 64KB
of the address space (note that the length `len` is controlled by
the peer). In this case, the bounds check will be bypassed, leading
to `*p` exceed the message bounds by up to 64KB when leaving
`ssl_parse_server_psk_hint()`. In a pure PSK-based handshake,
this doesn't seem to have any consequences, as `*p*` is not accessed
afterwards. In a PSK-(EC)DHE handshake, however, `*p` is read from
in `ssl_parse_server_ecdh_params()` and `ssl_parse_server_dh_params()`
which might lead to an application crash of information leakage.
Change the secondary X509 CSR parsing call for the alternative MS header to only
occur if the first call fails due to the header being unfound, instead of any
call.
Add support for RFC7468, and the alternative Microsoft footer/headers for CSR's
that contain the text 'BEGIN NEW CERTIFICATE REQUEST' instead of
'BEGIN CERTIFICATE REQUEST'.
Get rid of the variable p. This makes it more apparent where the code
accesses the buffer at an offset whose value is sensitive.
No intended behavior change in this commit.
Rather than doing the quadratic-time constant-memory-trace on the
whole working buffer, do it on the section of the buffer where the
data to copy has to lie, which can be significantly smaller if the
output buffer is significantly smaller than the working buffer, e.g.
for TLS RSA ciphersuites (48 bytes vs MBEDTLS_MPI_MAX_SIZE).
