The entropy context contains a SHA-256 or SHA-512 context for entropy
mixing, but doesn't initialize / free this context properly in the
initialization and freeing functions `mbedtls_entropy_init` and
`mbedtls_entropy_free` through a call to `mbedtls_sha{256/512}_init`
resp. `mbedtls_sha{256/512}_free`. Instead, only a zeroization of the
entire entropy structure is performed. This doesn't lead to problems
for the current software implementations of SHA-256 and SHA-512 because
zeroization is proper initialization for them, but it may (and does)
cause problems for alternative implementations of SHA-256 and SHA-512
that use context structures that cannot be properly initialized through
zeroization. This commit fixes this. Found and fix suggested by ccli8.
* mbedtls-2.1:
selftest: fix build error in some configurations
Timing self test: shorten redundant tests
Timing self test: increased duration
Timing self test: increased tolerance
selftest: allow excluding a subset of the tests
selftest: allow running a subset of the tests
selftest: fixed an erroneous return code
selftest: refactor to separate the list of tests from the logic
Timing self test: print some diagnosis information
mbedtls_timing_get_timer: don't use uninitialized memory
timing interface documentation: minor clarifications
Timing: fix mbedtls_set_alarm(0) on Unix/POSIX
Increase the duration of the self test, otherwise it tends to fail on
a busy machine even with the recently upped tolerance. But run the
loop only once, it's enough for a simple smoke test.
mbedtls_timing_self_test fails annoyingly often when running on a busy
machine such as can be expected of a continous integration system.
Increase the tolerances in the delay test, to reduce the chance of
failures that are only due to missing a deadline on a busy machine.
Print some not-very-nice-looking but helpful diagnosis information if
the timing selftest fails. Since the failures tend to be due to heavy
system load that's hard to reproduce, this information is necessary to
understand what's going on.
mbedtls_timing_get_timer with reset=1 is called both to initialize a
timer object and to reset an already-initialized object. In an
initial call, the content of the data structure is indeterminate, so
the code should not read from it. This could crash if signed overflows
trap, for example.
As a consequence, on reset, we can't return the previously elapsed
time as was previously done on Windows. Return 0 as was done on Unix.
The POSIX/Unix implementation of mbedtls_set_alarm did not set the
mbedtls_timing_alarmed flag when called with 0, which was inconsistent
with what the documentation implied and with the Windows behavior.
* restricted/pr/412:
Correct record header size in case of TLS
Don't allocate space for DTLS header if DTLS is disabled
Improve debugging output
Adapt ChangeLog
Add run-time check for handshake message size in ssl_write_record
Add run-time check for record content size in ssl_encrypt_buf
Add compile-time checks for size of record content and payload
In a previous PR (Fix heap corruption in implementation of truncated HMAC
extension #425) the place where MAC is computed was changed from the end of
the SSL I/O buffer to a local buffer (then (part of) the content of the local
buffer is either copied to the output buffer of compare to the input buffer).
Unfortunately, this change was made only for TLS 1.0 and later, leaving SSL
3.0 in an inconsistent state due to ssl_mac() still writing to the old,
hard-coded location, which, for MAC verification, resulted in later comparing
the end of the input buffer (containing the computed MAC) to the local buffer
(uninitialised), most likely resulting in MAC verification failure, hence no
interop (even with ourselves).
This commit completes the move to using a local buffer by using this strategy
for SSL 3.0 too. Fortunately ssl_mac() was static so it's not a problem to
change its signature.
Fix the x509_get_subject_alt_name() function to not accept invalid
tags. The problem was that the ASN.1 class for tags consists of two
bits. Simply doing bit-wise and of the CONTEXT_SPECIFIC macro with the
input tag has the potential of accepting tag values 0x10 (private)
which would indicate that the certificate has an incorrect format.
In case truncated HMAC must be used but the Mbed TLS peer hasn't been updated
yet, one can use the compile-time option MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT to
temporarily fall back to the old, non-compliant implementation of the truncated
HMAC extension.
The truncated HMAC extension as described in
https://tools.ietf.org/html/rfc6066.html#section-7 specifies that when truncated
HMAC is used, only the HMAC output should be truncated, while the HMAC key
generation stays unmodified. This commit fixes Mbed TLS's behavior of also
truncating the key, potentially leading to compatibility issues with peers
running other stacks than Mbed TLS.
Details:
The keys for the MAC are pieces of the keyblock that's generated from the
master secret in `mbedtls_ssl_derive_keys` through the PRF, their size being
specified as the size of the digest used for the MAC, regardless of whether
truncated HMAC is enabled or not.
/----- MD size ------\ /------- MD size ----\
Keyblock +----------------------+----------------------+------------------+---
now | MAC enc key | MAC dec key | Enc key | ...
(correct) +----------------------+----------------------+------------------+---
In the previous code, when truncated HMAC was enabled, the HMAC keys
were truncated to 10 bytes:
/-10 bytes-\ /-10 bytes-\
Keyblock +-------------+-------------+------------------+---
previously | MAC enc key | MAC dec key | Enc key | ...
(wrong) +-------------+-------------+------------------+---
The reason for this was that a single variable `transform->maclen` was used for
both the keysize and the size of the final MAC, and its value was reduced from
the MD size to 10 bytes in case truncated HMAC was negotiated.
This commit fixes this by introducing a temporary variable `mac_key_len` which
permanently holds the MD size irrespective of the presence of truncated HMAC,
and using this temporary to obtain the MAC key chunks from the keyblock.
Fix missing definition of mbedtls_zeroize when MBEDTLS_FS_IO is
disabled in the configuration.
Introduced by d08ae68237
Merge remote-tracking branch 'upstream-public/pr/1112' into mbedtls-2.1
Previously, MAC validation for an incoming record proceeded as follows:
1) Make a copy of the MAC contained in the record;
2) Compute the expected MAC in place, overwriting the presented one;
3) Compare both.
This resulted in a record buffer overflow if truncated MAC was used, as in this
case the record buffer only reserved 10 bytes for the MAC, but the MAC
computation routine in 2) always wrote a full digest.
For specially crafted records, this could be used to perform a controlled write of
up to 6 bytes past the boundary of the heap buffer holding the record, thereby
corrupting the heap structures and potentially leading to a crash or remote code
execution.
This commit fixes this by making the following change:
1) Compute the expected MAC in a temporary buffer that has the size of the
underlying message digest.
2) Compare to this to the MAC contained in the record, potentially
restricting to the first 10 bytes if truncated HMAC is used.
A similar fix is applied to the encryption routine `ssl_encrypt_buf`.
* mbedtls-2.1:
Fix typo in asn1.h
Improve leap year test names in x509parse.data
Correctly handle leap year in x509_date_is_valid()
Renegotiation: Add tests for SigAlg ext parsing
Parse Signature Algorithm ext when renegotiating
Fix changelog for ssl_server2.c usage fix
Fix ssl_server2 sample application prompt
Update ChangeLog for fix to #836
Enhance documentation of ssl_write_hostname_ext, adapt ChangeLog.
Enhance documentation of mbedtls_ssl_set_hostname
Add test case calling ssl_set_hostname twice
Make mbedtls_ssl_set_hostname safe to be called multiple times
Fix typo in configs/README.txt file
The function mbedtls_ecp_gen_keypair_base did not wipe the stack buffer used to
hold the private exponent before returning. This commit fixes this by not using
a stack buffer in the first place but instead calling mpi_fill_random directly
to acquire the necessary random MPI.
This commit modifies mpi_read_binary to always allocate the minimum number of
limbs required to hold the entire buffer provided to the function, regardless of
its content. Previously, leading zero bytes in the input data were detected and
used to reduce memory footprint and time, but this non-constant behavior turned
out to be non-tolerable for the cryptographic applications this function is used
for.
Previously, if `MBEDTLS_SSL_RENEGOTIATION` was disabled, incoming handshake
messages in `mbedtls_ssl_read` (expecting application data) lead to the
connection being closed. This commit fixes this, restricting the
`MBEDTLS_SSL_RENEGOTIATION`-guard to the code-paths responsible for accepting
renegotiation requests and aborting renegotiation attempts after too many
unexpected records have been received.
Remove a check introduced in the previous buffer overflow fix with keys of
size 8N+1 which the subsequent fix for buffer start calculations made
redundant.
Added a changelog entry for the buffer start calculation fix.
This commit fixes a comparison of ssl_session->encrypt_then_mac against the
ETM-unrelated constant MBEDTLS_SSL_EXTENDED_MS_DISABLED. Instead,
MBEDTLS_SSL_ETM_DISABLED should be used.
The typo is has no functional effect since both constants have the same value 0.
For a key of size 8N+1, check that the first byte after applying the
public key operation is 0 (it could have been 1 instead). The code was
incorrectly doing a no-op check instead, which led to invalid
signatures being accepted. Not a security flaw, since you would need the
private key to craft such an invalid signature, but a bug nonetheless.
The check introduced by the previous security fix was off by one. It
fixed the buffer overflow but was not compliant with the definition of
PSS which technically led to accepting some invalid signatures (but
not signatures made without the private key).
Fix buffer overflow in RSA-PSS signature verification when the hash is
too large for the key size. Found by Seth Terashima, Qualcomm.
Added a non-regression test and a positive test with the smallest
permitted key size for a SHA-512 hash.
Signature algorithm extension was skipped when renegotiation was in
progress, causing the signature algorithm not to be known when
renegotiating, and failing the handshake. Fix removes the renegotiation
step check before parsing the extension.
State explicitly that `pk_parse_pkcs8_undencrypted_der` and `pk_parse_key_pkcs8_encrypted_der` are not responsible for
zeroizing and freeing the provided key buffer.
This commit removes extension-writing code for X.509 non-v3 certificates from
mbedtls_x509write_crt_der. Previously, even if no extensions were present an
empty sequence would have been added.
The stack buffer used to hold the decrypted key in pk_parse_pkcs8_encrypted_der
was statically sized to 2048 bytes, which is not enough for DER encoded 4096bit
RSA keys.
This commit resolves the problem by performing the key-decryption in-place,
circumventing the introduction of another stack or heap copy of the key.
There are two situations where pk_parse_pkcs8_encrypted_der is invoked:
1. When processing a PEM-encoded encrypted key in mbedtls_pk_parse_key.
This does not need adaption since the PEM context used to hold the decoded
key is already constructed and owned by mbedtls_pk_parse_key.
2. When processing a DER-encoded encrypted key in mbedtls_pk_parse_key.
In this case, mbedtls_pk_parse_key calls pk_parse_pkcs8_encrypted_der with
the buffer provided by the user, which is declared const. The commit
therefore adds a small code paths making a copy of the keybuffer before
calling pk_parse_pkcs8_encrypted_der.
Although the variable ret was initialised to an error, the
MBEDTLS_MPI_CHK macro was overwriting it. Therefore it ended up being
0 whenewer the bignum computation was successfull and stayed 0
independently of the actual check.
This commit adds the macro ENTROPY_HAVE_STRONG to the helper test file tests/suites/helpers.function to be able to make
tests depend on the presence of strong entropy.
There were preprocessor directives in pk.c and pk_wrap.c that cheked
whether the bit length of size_t was greater than that of unsigned int.
However, the check relied on the MBEDTLS_HAVE_INT64 macro being defined
which is not directly related to size_t. This might result in errors in
some platforms. This change modifies the check to use the macros
SIZE_MAX and UINT_MAX instead making the code more robust.
As noted in #557, several functions use 'index' resp. 'time'
as parameter names in their declaration and/or definition, causing name
conflicts with the functions in the C standard library of the same
name some compilers warn about.
This commit renames the arguments accordingly.
