The following two quantities:
SecDataDir->VirtualAddress + SecDataDir->Size
SecDataDir->VirtualAddress + SecDataDir->Size - OffSet
are used multiple times in DxeImageVerificationHandler(). Introduce helper
variables for them: "SecDataDirEnd" and "SecDataDirLeft", respectively.
This saves us multiple calculations and significantly simplifies the code.
Note that all three summands above have type UINT32, therefore the new
variables are also of type UINT32.
This patch does not change behavior.
(Note that the code already handles the case when the
SecDataDir->VirtualAddress + SecDataDir->Size
UINT32 addition overflows -- namely, in that case, the certificate loop is
never entered, and the corruption check right after the loop fires.)
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Wenyi Xie <xiewenyi2@huawei.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2215
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200901091221.20948-2-lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Wenyi Xie <xiewenyi2@huawei.com>
Reviewed-by: Min M Xu <min.m.xu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1608
To avoid false-negative issue in check hash against dbx, both error
condition (as return value) and check result (as out parameter) of
IsSignatureFoundInDatabase() are added. So the caller of this function
will know exactly if a failure is caused by a black list hit or
other error happening, and enforce a more secure operation to prevent
secure boot from being bypassed. For a white list check (db), there's
no such necessity.
All intermediate results inside this function will be checked and
returned immediately upon any failure or error, like out-of-resource,
hash calculation error or certificate retrieval failure.
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1608
To avoid false-negative issue in check hash against dbx, both error
condition (as return value) and check result (as out parameter) of
IsCertHashFoundInDatabase() are added. So the caller of this function
will know exactly if a failure is caused by a black list hit or
other error happening, and enforce a more secure operation to prevent
secure boot from being bypassed. For a white list check (db), there's
no such necessity.
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1608
The dbx fetching code inside the while/for-loop causes code hard to
understand. Since there's no need to get dbx more than once, this patch
simplify the code logic by moving related code to be outside the while-
loop. db fetching code is also refined accordingly to reduce the indent
level of code.
More comments are also added or refined to explain more details.
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1608
In timestamp check after the cert is found in db, the original code jumps
to 'Done' if any error happens in fetching dbx variable. At any of the
jump, VerifyStatus equals to TRUE, which means allowed-by-db. This should
not be allowed except to EFI_NOT_FOUND case (meaning dbx doesn't exist),
because it could be used to bypass timestamp check.
This patch add code to change VerifyStatus to FALSE in the case of memory
allocation failure and dbx fetching failure to avoid potential bypass
issue.
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1608
Normally two times of calling gRT->GetVariable() are needed to get
the data of a variable: get the variable size by passing zero variable
size, and then allocate enough memory and pass the correct variable size
and buffer.
But in the inner loop in IsAllowedByDb(), the DbxDataSize was not
initialized to zero before calling gRT->GetVariable(). It won't cause
problem if dbx does not exist. But it will give wrong result if dbx
exists and the DbxDataSize happens to be a small enough value. In this
situation, EFI_BUFFER_TOO_SMALL will be returned. Then the result check
code followed will jump to 'Done', which is not correct because it's
actually the value expected.
if (Status == EFI_BUFFER_TOO_SMALL) {
goto Done;
}
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
In case the signers' certificate stack, retrieved from the PE/COFF image's
Authenticode blob, has zero elements (=there are zero signer certificates),
then we should consider the image forbidden by DBX, not accepted by DBX.
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
In DxeImageVerificationHandler(), we should return EFI_SECURITY_VIOLATION
for a rejected image only if the platform sets
DEFER_EXECUTE_ON_SECURITY_VIOLATION as the policy for the image's source.
Otherwise, EFI_ACCESS_DENIED must be returned.
Right now, EFI_SECURITY_VIOLATION is returned for all rejected images,
which is wrong -- it causes LoadImage() to hold on to rejected images (in
untrusted state), for further platform actions. However, if a platform
already set DENY_EXECUTE_ON_SECURITY_VIOLATION, the platform will not
expect the rejected image to stick around in memory (regardless of its
untrusted state).
Therefore, adhere to the platform policy in the return value of the
DxeImageVerificationHandler() function.
Furthermore, according to "32.4.2 Image Execution Information Table" in
the UEFI v2.8 spec, and considering that edk2 only supports (AuditMode==0)
at the moment:
> When AuditMode==0, if the image's signature is not found in the
> authorized database, or is found in the forbidden database, the image
> will not be started and instead, information about it will be placed in
> this table.
we have to store an EFI_IMAGE_EXECUTION_INFO record in both the "defer"
case and the "deny" case. Thus, the AddImageExeInfo() call is not being
made conditional on (Policy == DEFER_EXECUTE_ON_SECURITY_VIOLATION); the
documentation is updated instead.
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2129
Fixes: 5db28a6753
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200116190705.18816-12-lersek@redhat.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
[lersek@redhat.com: push with Mike's R-b due to Chinese New Year
Holiday: <https://edk2.groups.io/g/devel/message/53429>; msgid
<d3fbb76dabed4e1987c512c328c82810@intel.com>]
It makes no sense to call AddImageExeInfo() with (Signature == NULL) and
(SignatureSize > 0). AddImageExeInfo() does not crash in such a case -- it
avoids the CopyMem() call --, but it creates an invalid
EFI_IMAGE_EXECUTION_INFO record. Namely, the
"EFI_IMAGE_EXECUTION_INFO.InfoSize" field includes "SignatureSize", but
the actual signature bytes are not filled in.
Document and ASSERT() this condition in AddImageExeInfo().
In DxeImageVerificationHandler(), zero out "SignatureListSize" if we set
"SignatureList" to NULL due to AllocateZeroPool() failure.
(Another approach could be to avoid calling AddImageExeInfo() completely,
in case AllocateZeroPool() fails. Unfortunately, the UEFI v2.8 spec does
not seem to state clearly whether a signature is mandatory in
EFI_IMAGE_EXECUTION_INFO, if the "Action" field is
EFI_IMAGE_EXECUTION_AUTH_SIG_FAILED or EFI_IMAGE_EXECUTION_AUTH_SIG_FOUND.
For now, the EFI_IMAGE_EXECUTION_INFO addition logic is not changed; we
only make sure that the record we add is not malformed.)
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2129
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200116190705.18816-11-lersek@redhat.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
[lersek@redhat.com: push with Mike's R-b due to Chinese New Year
Holiday: <https://edk2.groups.io/g/devel/message/53429>; msgid
<d3fbb76dabed4e1987c512c328c82810@intel.com>]
Inside the "for" loop that scans the signatures of the image, we call
HashPeImageByType(), and assign its return value to "Status".
Beyond the immediate retval check, this assignment is useless (never
consumed). That's because a subsequent access to "Status" may only be one
of the following:
- the "Status" assignment when we call HashPeImageByType() in the next
iteration of the loop,
- the "Status = EFI_ACCESS_DENIED" assignment right after the final
"IsVerified" check.
To make it clear that the assignment is only useful for the immediate
HashPeImageByType() retval check, introduce a specific helper variable,
called "HashStatus".
This patch is a no-op, functionally.
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2129
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200116190705.18816-5-lersek@redhat.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
[lersek@redhat.com: push with Mike's R-b due to Chinese New Year
Holiday: <https://edk2.groups.io/g/devel/message/53429>; msgid
<d3fbb76dabed4e1987c512c328c82810@intel.com>]
The PeCoffLoaderGetImageInfo() function may return various error codes,
such as RETURN_INVALID_PARAMETER and RETURN_UNSUPPORTED.
Such error values should not be assigned to our "Status" variable in the
DxeImageVerificationHandler() function, because "Status" generally stands
for the main exit value of the function. And
SECURITY2_FILE_AUTHENTICATION_HANDLER functions are expected to return one
of EFI_SUCCESS, EFI_SECURITY_VIOLATION, and EFI_ACCESS_DENIED only.
Introduce the "PeCoffStatus" helper variable for keeping the return value
of PeCoffLoaderGetImageInfo() internal to the function. If
PeCoffLoaderGetImageInfo() fails, we'll jump to the "Done" label with
"Status" being EFI_ACCESS_DENIED, inherited from the top of the function.
Note that this is consistent with the subsequent PE/COFF Signature check,
where we jump to the "Done" label with "Status" having been re-set to
EFI_ACCESS_DENIED.
As a consequence, we can at once remove the
Status = EFI_ACCESS_DENIED;
assignment right after the "PeCoffStatus" check.
This patch does not change the control flow in the function, it only
changes the "Status" outcome from API-incompatible error codes to
EFI_ACCESS_DENIED, under some circumstances.
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2129
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200116190705.18816-4-lersek@redhat.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
[lersek@redhat.com: push with Mike's R-b due to Chinese New Year
Holiday: <https://edk2.groups.io/g/devel/message/53429>; msgid
<d3fbb76dabed4e1987c512c328c82810@intel.com>]
1. Do not use tab characters
2. No trailing white space in one line
3. All files must end with CRLF
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liming Gao <liming.gao@intel.com>
For pointer subtraction, the result is of type "ptrdiff_t". According to
the C11 standard (Committee Draft - April 12, 2011):
"When two pointers are subtracted, both shall point to elements of the
same array object, or one past the last element of the array object; the
result is the difference of the subscripts of the two array elements. The
size of the result is implementation-defined, and its type (a signed
integer type) is ptrdiff_t defined in the <stddef.h> header. If the result
is not representable in an object of that type, the behavior is
undefined."
In our codes, there are cases that the pointer subtraction is not
performed by pointers to elements of the same array object. This might
lead to potential issues, since the behavior is undefined according to C11
standard.
Also, since the size of type "ptrdiff_t" is implementation-defined. Some
static code checkers may warn that the pointer subtraction might underflow
first and then being cast to a bigger size. For example:
UINT8 *Ptr1, *Ptr2;
UINTN PtrDiff;
...
PtrDiff = (UINTN) (Ptr1 - Ptr2);
The commit will refine the pointer subtraction expressions by casting each
pointer to UINTN first and then perform the subtraction:
PtrDiff = (UINTN) Ptr1 - (UINTN) Ptr2;
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>
The input PeImage in HashPeImage() has been checked.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>
In image verification, if image verified pass in DBT, still need to verify if it is blocked by any other cert/cert hash from DBX.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Chao Zhang <chao.b.zhang@intel.com>
Reviewed-by: Long Qin <qin.long@intel.com>
Reviewed-by: Dick Wilkins <dick_wilkins@phoenix.com>
Per UEFI spec, EFI_IMAGE_EXECUTION_INFO structure is updated to comment
Signature field. So, its structure doesn't include Signature field. But,
ImageExeInfoEntrySize uses its structure size minor Signature size. It
will be corrected in this change.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17687 6f19259b-4bc3-4df7-8a09-765794883524
This patch added one new X509GetTBSCert() interface in BaseCryptLib to retrieve the TBSCertificate,
and also corrected the hash calculation for revoked certificate to aligned the RFC3280 and UEFI 2.4 spec.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: "Long, Qin" <qin.long@intel.com>
Reviewed-by: "Dong, Guo" <guo.dong@initel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16559 6f19259b-4bc3-4df7-8a09-765794883524
