This change adds optional support for
- Armv8.3-A Pointer Authentication (PAuth) and
- Armv8.5-A Branch Target Identification (BTI)
features to the perl scripts.
Both features can be enabled with additional compiler flags.
Unless any of these are enabled explicitly there is no code change at
all.
The extensions are briefly described below. Please read the appropriate
chapters of the Arm Architecture Reference Manual for the complete
specification.
Scope
-----
This change only affects generated assembly code.
Armv8.3-A Pointer Authentication
--------------------------------
Pointer Authentication extension supports the authentication of the
contents of registers before they are used for indirect branching
or load.
PAuth provides a probabilistic method to detect corruption of register
values. PAuth signing instructions generate a Pointer Authentication
Code (PAC) based on the value of a register, a seed and a key.
The generated PAC is inserted into the original value in the register.
A PAuth authentication instruction recomputes the PAC, and if it matches
the PAC in the register, restores its original value. In case of a
mismatch, an architecturally unmapped address is generated instead.
With PAuth, mitigation against ROP (Return-oriented Programming) attacks
can be implemented. This is achieved by signing the contents of the
link-register (LR) before it is pushed to stack. Once LR is popped,
it is authenticated. This way a stack corruption which overwrites the
LR on the stack is detectable.
The PAuth extension adds several new instructions, some of which are not
recognized by older hardware. To support a single codebase for both pre
Armv8.3-A targets and newer ones, only NOP-space instructions are added
by this patch. These instructions are treated as NOPs on hardware
which does not support Armv8.3-A. Furthermore, this patch only considers
cases where LR is saved to the stack and then restored before branching
to its content. There are cases in the code where LR is pushed to stack
but it is not used later. We do not address these cases as they are not
affected by PAuth.
There are two keys available to sign an instruction address: A and B.
PACIASP and PACIBSP only differ in the used keys: A and B, respectively.
The keys are typically managed by the operating system.
To enable generating code for PAuth compile with
-mbranch-protection=<mode>:
- standard or pac-ret: add PACIASP and AUTIASP, also enables BTI
(read below)
- pac-ret+b-key: add PACIBSP and AUTIBSP
Armv8.5-A Branch Target Identification
--------------------------------------
Branch Target Identification features some new instructions which
protect the execution of instructions on guarded pages which are not
intended branch targets.
If Armv8.5-A is supported by the hardware, execution of an instruction
changes the value of PSTATE.BTYPE field. If an indirect branch
lands on a guarded page the target instruction must be one of the
BTI <jc> flavors, or in case of a direct call or jump it can be any
other instruction. If the target instruction is not compatible with the
value of PSTATE.BTYPE a Branch Target Exception is generated.
In short, indirect jumps are compatible with BTI <j> and <jc> while
indirect calls are compatible with BTI <c> and <jc>. Please refer to the
specification for the details.
Armv8.3-A PACIASP and PACIBSP are implicit branch target
identification instructions which are equivalent with BTI c or BTI jc
depending on system register configuration.
BTI is used to mitigate JOP (Jump-oriented Programming) attacks by
limiting the set of instructions which can be jumped to.
BTI requires active linker support to mark the pages with BTI-enabled
code as guarded. For ELF64 files BTI compatibility is recorded in the
.note.gnu.property section. For a shared object or static binary it is
required that all linked units support BTI. This means that even a
single assembly file without the required note section turns-off BTI
for the whole binary or shared object.
The new BTI instructions are treated as NOPs on hardware which does
not support Armv8.5-A or on pages which are not guarded.
To insert this new and optional instruction compile with
-mbranch-protection=standard (also enables PAuth) or +bti.
When targeting a guarded page from a non-guarded page, weaker
compatibility restrictions apply to maintain compatibility between
legacy and new code. For detailed rules please refer to the Arm ARM.
Compiler support
----------------
Compiler support requires understanding '-mbranch-protection=<mode>'
and emitting the appropriate feature macros (__ARM_FEATURE_BTI_DEFAULT
and __ARM_FEATURE_PAC_DEFAULT). The current state is the following:
-------------------------------------------------------
| Compiler | -mbranch-protection | Feature macros |
+----------+---------------------+--------------------+
| clang | 9.0.0 | 11.0.0 |
+----------+---------------------+--------------------+
| gcc | 9 | expected in 10.1+ |
-------------------------------------------------------
Available Platforms
------------------
Arm Fast Model and QEMU support both extensions.
https://developer.arm.com/tools-and-software/simulation-models/fast-modelshttps://www.qemu.org/
Implementation Notes
--------------------
This change adds BTI landing pads even to assembly functions which are
likely to be directly called only. In these cases, landing pads might
be superfluous depending on what code the linker generates.
Code size and performance impact for these cases would be negligible.
Interaction with C code
-----------------------
Pointer Authentication is a per-frame protection while Branch Target
Identification can be turned on and off only for all code pages of a
whole shared object or static binary. Because of these properties if
C/C++ code is compiled without any of the above features but assembly
files support any of them unconditionally there is no incompatibility
between the two.
Useful Links
------------
To fully understand the details of both PAuth and BTI it is advised to
read the related chapters of the Arm Architecture Reference Manual
(Arm ARM):
https://developer.arm.com/documentation/ddi0487/latest/
Additional materials:
"Providing protection for complex software"
https://developer.arm.com/architectures/learn-the-architecture/providing-protection-for-complex-software
Arm Compiler Reference Guide Version 6.14: -mbranch-protection
https://developer.arm.com/documentation/101754/0614/armclang-Reference/armclang-Command-line-Options/-mbranch-protection?lang=en
Arm C Language Extensions (ACLE)
https://developer.arm.com/docs/101028/latest
Addional Notes
--------------
This patch is a copy of the work done by Tamas Petz in boringssl. It
contains the changes from the following commits:
aarch64: support BTI and pointer authentication in assembly
Change-Id: I4335f92e2ccc8e209c7d68a0a79f1acdf3aeb791
URL: https://boringssl-review.googlesource.com/c/boringssl/+/42084
aarch64: Improve conditional compilation
Change-Id: I14902a64e5f403c2b6a117bc9f5fb1a4f4611ebf
URL: https://boringssl-review.googlesource.com/c/boringssl/+/43524
aarch64: Fix name of gnu property note section
Change-Id: I6c432d1c852129e9c273f6469a8b60e3983671ec
URL: https://boringssl-review.googlesource.com/c/boringssl/+/44024
Change-Id: I2d95ebc5e4aeb5610d3b226f9754ee80cf74a9af
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16674)
Some of the functions are being called on NULL bio with the
expectation that such call will not raise an error.
Fixes#16681
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/16686)
This is done using a single global lock. The premise for this is that new
objects will most frequently be added at start up and never added subsequently.
Thus, the locking will be for read most of the time.
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15713)
This is done using a single global lock. The premise for this is that new
objects will most frequently be added at start up and never added subsequently.
Thus, the locking will be for read most of the time.
This does, however, introduce the overhead of taking an uncontested read lock
when accessing the object database.
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15713)
The header is already included by <windows.h> for WinSDK 8 or later.
Actually this causes problem for WinSDK 7.1 (defaults for VS2010) that
it does not have this header while SRW Locks do exist for Windows 7.
CLA: trivial
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16603)
It is better to use array bounds for improved
gcc warning checks.
While "uint8_t*" allows arbitrary pointer arithmetic
using "uint8_t[SER_BYTES]" limits the pointer arithmetic
to the range 0..SER_BYTES.
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16376)
CLA:trivial
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16503)
In a chain of decoders, the first that specifies an input structure
gets it compared with the structure specified by the user, if there is
one. If they aren't the same, that decoder is skipped.
Because the first structure can appear anywhere along a chain of
decoders, not just the decoders associated with the resulting OpenSSL
type, the code that checked the structure name when building up the
chain of decoders is removed.
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16466)
If the internal operations dupctx() fails then a free is done (e.g. EVP_KEYEXCH_free()). If this is not set to NULL the EVP_PKEY_CTX_free() will do a double free.
This was found by testing kdf_dupctx() in kdf_exch.c (Note this always
fails since the internal KDF's do not have a dup method).
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16495)
When building the certificate chain, prioritise any Cert(0) Full(0)
certificates from TLSA records over certificates received from the peer.
This is important when the server sends a cross cert, but TLSA records include
the underlying root CA cert. We want to construct a chain with the issuer from
the TLSA record, which can then match the TLSA records (while the associated
cross cert may not).
Reviewed-by: Tomáš Mráz <tomas@openssl.org>
There is no point using it becuase they are getting full quality entropy from
the primary DRBG (which remains using the d.f.).
Also cleaned up the parameter passing to the DRBGs to not pass parameters that
are unknown.
Fixes#16117
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16156)
(kfreebsd-amd64, kfreebsd-i386). The error reported by the compiler
is:
../crypto/uid.c: In function 'OPENSSL_issetugid':
../crypto/uid.c:50:22: error: 'AT_SECURE' undeclared (first use in this function)
50 | return getauxval(AT_SECURE) != 0;
| ^~~~~~~~~
This commit changes the code to use the freebsd code in this case.
This fixes the compilation.
CLA: trivial
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16477)
We should not assume that the type of an ASN.1 value is UTF8String as
expected. We must actually check it, otherwise we could get a NULL ptr
deref, or worse memory errors.
Reported by David Benjamin.
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16443)
The previous commit provided some guidelines and some rules for using
locking in order to avoid deadlocks. This commit refactors the code in
order to adhere to those guidelines and rules.
Fixes#16312
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16469)
Provide some guidelines, as well as some rules for using the locks in
provider_core.c, in order to avoid the introduction of deadlocks.
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16469)
This fixes the following error with gcc10 under strict ANSI conditions:
.../crypto/bio/bss_dgram.c:373:20: error: 'const struct in6_addr' has no member named 's6_addr32'
CLA: trivial
Fixes#16449
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/16451)
Avoid races where 2 threads attempt to configure activation of providers
at the same time. E.g. via an explicit and an implict load of the config
file at the same time.
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16425)
We skip the activation if we already configured them.
Fixes#16250
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16425)
The legacy implementation duplicates the pctx before creating/verifying
the signature unless EVP_MD_CTX_FLAG_FINALISE is set. We have to do the
same with provided implementations.
Fixes#16321
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16422)
This allows for passing a NULL pointer with zero max_len.
Invoking memcpy on NULL is undefined behaviour, even if the size is zero.
https://en.cppreference.com/w/c/string/byte/memcpy
The function can now be queried for the necessary buffer length.
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10541)
Previously there was no check that the supplied buffer was large enough.
It was just assumed to be sufficient. Instead we should check and fail if
not.
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
Previously the length of the SM2 plaintext could be incorrectly calculated.
The plaintext length was calculated by taking the ciphertext length and
taking off an "overhead" value.
The overhead value was assumed to have a "fixed" element of 10 bytes.
This is incorrect since in some circumstances it can be more than 10 bytes.
Additionally the overhead included the length of two integers C1x and C1y,
which were assumed to be the same length as the field size (32 bytes for
the SM2 curve). However in some cases these integers can have an additional
padding byte when the msb is set, to disambiguate them from negative
integers. Additionally the integers can also be less than 32 bytes in
length in some cases.
If the calculated overhead is incorrect and larger than the actual value
this can result in the calculated plaintext length being too small.
Applications are likely to allocate buffer sizes based on this and therefore
a buffer overrun can occur.
CVE-2021-3711
Issue reported by John Ouyang.
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
Previously if an error path is entered a leak could result.
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David Benjamin <davidben@google.com>
If FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION is defined then we don't NUL
terminate ASN1_STRING datatypes. This shouldn't be necessary but we add it
any for safety in normal builds.
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David Benjamin <davidben@google.com>
Check that there's at least one byte in params->base before trying to
read it.
CVE-2021-3712
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David Benjamin <davidben@google.com>
ASN.1 strings may not be NUL terminated. Don't assume they are.
CVE-2021-3712
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David Benjamin <davidben@google.com>
ASN.1 strings may not be NUL terminated. Don't assume they are.
CVE-2021-3712
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David Benjamin <davidben@google.com>
ASN.1 strings may not be NUL terminated. Don't assume they are.
CVE-2021-3712
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David Benjamin <davidben@google.com>
ASN.1 strings may not be NUL terminated. Don't assume they are.
CVE-2021-3712
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David Benjamin <davidben@google.com>
ASN.1 strings may not be NUL terminated. Don't assume they are.
CVE-2021-3712
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David Benjamin <davidben@google.com>
ASN.1 strings may not be NUL terminated. Don't assume they are.
CVE-2021-3712
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David Benjamin <davidben@google.com>
ASN.1 strings may not be NUL terminated. Don't assume they are.
CVE-2021-3712
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David Benjamin <davidben@google.com>
ASN.1 strings may not be NUL terminated. Don't assume they are.
CVE-2021-3712
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David Benjamin <davidben@google.com>
A check is added to fail this function if the string buffer isn't
large enough to accomodate a terminating NUL byte.
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16334)
