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NetworkPkg/IScsiDxe: clean up "ISCSI_CHAP_AUTH_DATA.OutChallengeLength" 

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>
This commit is contained in:
Laszlo Ersek 2021-06-08 14:12:52 +02:00 committed by mergify[bot]
parent 29cab43bb7
commit 95616b8661
2 changed files with 7 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
NetworkPkg/IScsiDxe/IScsiCHAP.c
View File

@ -122,7 +122,7 @@ IScsiCHAPAuthTarget (
AuthData->AuthConfig->ReverseCHAPSecret,
SecretSize,
AuthData->OutChallenge,
AuthData->OutChallengeLength,
ISCSI_CHAP_RSP_LEN, // ChallengeLength
VerifyRsp
);
@ -490,7 +490,6 @@ IScsiCHAPToSendReq (
// CHAP_C=<C>
//
IScsiGenRandom ((UINT8 *) AuthData->OutChallenge, ISCSI_CHAP_RSP_LEN);
AuthData->OutChallengeLength = ISCSI_CHAP_RSP_LEN;
IScsiBinToHex (
(UINT8 *) AuthData->OutChallenge,
ISCSI_CHAP_RSP_LEN,

9
NetworkPkg/IScsiDxe/IScsiCHAP.h
View File

@ -19,7 +19,6 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
#define ISCSI_CHAP_ALGORITHM_MD5 5
#define ISCSI_CHAP_AUTH_MAX_LEN 1024
///
/// MD5_HASHSIZE
///
@ -59,9 +58,13 @@ typedef struct _ISCSI_CHAP_AUTH_DATA {
//
// Auth-data to be sent out for mutual authentication.
//
// While the challenge size is technically independent of the hashing
// algorithm, it is good practice to avoid hashing *fewer bytes* than the
// digest size. In other words, it's good practice to feed *at least as many
// bytes* to the hashing algorithm as the hashing algorithm will output.
//
UINT32 OutIdentifier;
UINT8 OutChallenge[ISCSI_CHAP_AUTH_MAX_LEN];
UINT32 OutChallengeLength;
UINT8 OutChallenge[ISCSI_CHAP_RSP_LEN];
} ISCSI_CHAP_AUTH_DATA;
/**