[edk2-devel] [PUBLIC edk2 PATCH v2 00/10] NetworkPkg/IScsiDxe: fix IScsiHexToBin() security and functionality bugs -- push #1698
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Working with overlong lines is difficult for me; rewrap the CHAP-related source files in IScsiDxe to 80 characters width. No functional changes. Cc: Jiaxin Wu <jiaxin.wu@intel.com> Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com> Cc: Philippe Mathieu-Daudé <philmd@redhat.com> Cc: Siyuan Fu <siyuan.fu@intel.com> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3356 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-Id: <20210608121259.32451-2-lersek@redhat.com>
The ISCSI_CHAP_AUTH_MAX_LEN macro is defined with value 1024. The usage of this macro currently involves a semantic (not functional) bug, which we're going to fix in a subsequent patch, eliminating ISCSI_CHAP_AUTH_MAX_LEN altogether. For now, remove the macro's usage from all "ISCSI_CHAP_AUTH_DATA.InChallenge" contexts. This is doable without duplicating open-coded constants. No changes in functionality. Cc: Jiaxin Wu <jiaxin.wu@intel.com> Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com> Cc: Philippe Mathieu-Daudé <philmd@redhat.com> Cc: Siyuan Fu <siyuan.fu@intel.com> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3356 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com> Message-Id: <20210608121259.32451-3-lersek@redhat.com>
The "ISCSI_CHAP_AUTH_DATA.OutChallenge" field is declared as a UINT8 array with ISCSI_CHAP_AUTH_MAX_LEN (1024) elements. However, when the challenge is generated and formatted, only ISCSI_CHAP_RSP_LEN (16) octets are used in the array. Change the array size to ISCSI_CHAP_RSP_LEN, and remove the (now unused) ISCSI_CHAP_AUTH_MAX_LEN macro. Remove the "ISCSI_CHAP_AUTH_DATA.OutChallengeLength" field, which is superfluous too. Most importantly, explain in a new comment *why* tying the challenge size to the digest size (ISCSI_CHAP_RSP_LEN) has always made sense. (See also Linux kernel commit 19f5f88ed779, "scsi: target: iscsi: tie the challenge length to the hash digest size", 2019-11-06.) For sure, the motivation that the new comment now explains has always been there, and has always been the same, for IScsiDxe; it's just that now we spell it out too. No change in peer-visible behavior. Cc: Jiaxin Wu <jiaxin.wu@intel.com> Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com> Cc: Philippe Mathieu-Daudé <philmd@redhat.com> Cc: Siyuan Fu <siyuan.fu@intel.com> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3356 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com> Message-Id: <20210608121259.32451-4-lersek@redhat.com>
Sort the library class dependencies in the #include directives and in the INF file. Remove the DpcLib class from the #include directives -- it is not listed in the INF file, and IScsiDxe doesn't call either DpcLib API (QueueDpc(), DispatchDpc()). No functional changes. Cc: Jiaxin Wu <jiaxin.wu@intel.com> Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com> Cc: Philippe Mathieu-Daudé <philmd@redhat.com> Cc: Siyuan Fu <siyuan.fu@intel.com> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3356 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com> Message-Id: <20210608121259.32451-5-lersek@redhat.com>
Considering IScsiBinToHex():
> if (((*HexLength) - 3) < BinLength * 2) {
> *HexLength = BinLength * 2 + 3;
> }
the following subexpressions are problematic:
(*HexLength) - 3
BinLength * 2
BinLength * 2 + 3
The first one may wrap under zero, the latter two may wrap over
MAX_UINT32.
Rewrite the calculation using SafeIntLib.
While at it, change the type of the "Index" variable from UINTN to UINT32.
The largest "Index"-based value that we calculate is
Index * 2 + 2 (with (Index == BinLength))
Because the patch makes
BinLength * 2 + 3
safe to calculate in UINT32, using UINT32 for
Index * 2 + 2 (with (Index == BinLength))
is safe too. Consistently using UINT32 improves readability.
This patch is best reviewed with "git show -W".
The integer overflows that this patch fixes are theoretical; a subsequent
patch in the series will audit the IScsiBinToHex() call sites, and show
that none of them can fail.
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Siyuan Fu <siyuan.fu@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3356
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210608121259.32451-6-lersek@redhat.com>
IScsiBinToHex() is called for encoding: - the answer to the target's challenge; that is, CHAP_R; - the challenge for the target, in case mutual authentication is enabled; that is, CHAP_C. The initiator controls the size of both blobs, the sizes of their hex encodings are correctly calculated in "RspLen" and "ChallengeLen". Therefore the IScsiBinToHex() calls never fail; assert that. Cc: Jiaxin Wu <jiaxin.wu@intel.com> Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com> Cc: Philippe Mathieu-Daudé <philmd@redhat.com> Cc: Siyuan Fu <siyuan.fu@intel.com> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3356 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com> Message-Id: <20210608121259.32451-7-lersek@redhat.com>
We'll need further return values for IScsiHexToBin() in a subsequent patch; make room for them in the leading comment block of the function. While at it, rewrap the comment block to 80 characters width. No functional changes. Cc: Jiaxin Wu <jiaxin.wu@intel.com> Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com> Cc: Philippe Mathieu-Daudé <philmd@redhat.com> Cc: Siyuan Fu <siyuan.fu@intel.com> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3356 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-Id: <20210608121259.32451-8-lersek@redhat.com>
The IScsiHexToBin() function has the following parser issues:
(1) If the *subject sequence* in "HexStr" is empty, the function returns
EFI_SUCCESS (with "BinLength" set to 0 on output). Such inputs should
be rejected.
(2) The function mis-handles a "HexStr" that ends with a stray nibble. For
example, if "HexStr" is "0xABC", the function decodes it to the bytes
{0xAB, 0x0C}, sets "BinLength" to 2 on output, and returns
EFI_SUCCESS. Such inputs should be rejected.
(3) If an invalid hex char is found in "HexStr", the function treats it as
end-of-hex-string, and returns EFI_SUCCESS. Such inputs should be
rejected.
All of the above cases are remotely triggerable, as shown in a subsequent
patch, which adds error checking to the IScsiHexToBin() call sites. While
the initiator is not immediately compromised, incorrectly parsing CHAP_R
from the target, in case of mutual authentication, is not great.
Extend the interface contract of IScsiHexToBin() with
EFI_INVALID_PARAMETER, for reporting issues (1) through (3), and implement
the new checks.
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Siyuan Fu <siyuan.fu@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3356
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210608121259.32451-9-lersek@redhat.com>
The IScsiHexToBin() function documents the EFI_BUFFER_TOO_SMALL return condition, but never actually checks whether the decoded buffer fits into the caller-provided room (i.e., the input value of "BinLength"), and EFI_BUFFER_TOO_SMALL is never returned. The decoding of "HexStr" can overflow "BinBuffer". This is remotely exploitable, as shown in a subsequent patch, which adds error checking to the IScsiHexToBin() call sites. This issue allows the target to compromise the initiator. Introduce EFI_BAD_BUFFER_SIZE, in addition to the existent EFI_BUFFER_TOO_SMALL, for reporting a special case of the buffer overflow, plus actually catch the buffer overflow. Cc: Jiaxin Wu <jiaxin.wu@intel.com> Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com> Cc: Philippe Mathieu-Daudé <philmd@redhat.com> Cc: Siyuan Fu <siyuan.fu@intel.com> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3356 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-Id: <20210608121259.32451-10-lersek@redhat.com>
IScsiDxe (that is, the initiator) receives two hex-encoded strings from
the iSCSI target:
- CHAP_C, where the target challenges the initiator,
- CHAP_R, where the target answers the challenge from the initiator (in
case the initiator wants mutual authentication).
Accordingly, we have two IScsiHexToBin() call sites:
- At the CHAP_C decoding site, check whether the decoding succeeds. The
decoded buffer ("AuthData->InChallenge") can accommodate 1024 bytes,
which is a permissible restriction on the target, per
<https://tools.ietf.org/html/rfc7143#section-12.1.3>. Shorter challenges
from the target are acceptable.
- At the CHAP_R decoding site, enforce that the decoding both succeed, and
provide exactly ISCSI_CHAP_RSP_LEN bytes. CHAP_R contains the digest
calculated by the target, therefore it must be of fixed size. We may
only call IScsiCHAPAuthTarget() if "TargetRsp" has been fully populated.
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Siyuan Fu <siyuan.fu@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3356
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com>
Message-Id: <20210608121259.32451-11-lersek@redhat.com>
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https://bugzilla.tianocore.org/show_bug.cgi?id=3356
Message-Id: 20210608121259.32451-1-lersek@redhat.com
https://listman.redhat.com/archives/edk2-devel-archive/2021-June/msg00316.html
https://edk2.groups.io/g/devel/message/76198