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integrity: Avoid -Wflex-array-member-not-at-end warnings

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-Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
ready to enable it globally.

There is currently an object (`hdr)` in `struct ima_max_digest_data`
that contains a flexible structure (`struct ima_digest_data`):

 struct ima_max_digest_data {
        struct ima_digest_data hdr;
        u8 digest[HASH_MAX_DIGESTSIZE];
 } __packed;

So, in order to avoid ending up with a flexible-array member in the
middle of a struct, we use the `__struct_group()` helper to separate
the flexible array from the rest of the members in the flexible
structure:

struct ima_digest_data {
        __struct_group(ima_digest_data_hdr, hdr, __packed,

        ... the rest of the members

        );
        u8 digest[];
} __packed;

And similarly for `struct evm_ima_xattr_data`.

With the change described above, we can now declare an object of the
type of the tagged `struct ima_digest_data_hdr`, without embedding the
flexible array in the middle of another struct:

 struct ima_max_digest_data {
        struct ima_digest_data_hdr hdr;
        u8 digest[HASH_MAX_DIGESTSIZE];
 } __packed;

And similarly for `struct evm_digest` and `struct evm_xattr`.

We also use `container_of()` whenever we need to retrieve a pointer to
the flexible structure.

So, with these changes, fix the following warnings:

security/integrity/evm/evm.h:64:32: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
security/integrity/evm/../integrity.h:40:35: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
security/integrity/evm/../integrity.h:68:32: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
security/integrity/ima/../integrity.h:40:35: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
security/integrity/ima/../integrity.h:68:32: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
security/integrity/integrity.h:40:35: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
security/integrity/integrity.h:68:32: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
security/integrity/platform_certs/../integrity.h:40:35: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
security/integrity/platform_certs/../integrity.h:68:32: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Link: https://github.com/KSPP/linux/issues/202
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This commit is contained in:
Gustavo A. R. Silva
2024-04-04 09:00:48 -06:00
committed by Mimi Zohar
parent cc293c8466
commit 38aa3f5ac6
7 changed files with 31 additions and 15 deletions
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4
security/integrity/ima/ima_appraise.c
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@@ -378,7 +378,9 @@ static int xattr_verify(enum ima_hooks func, struct ima_iint_cache *iint,
}
rc = calc_file_id_hash(IMA_VERITY_DIGSIG, iint->ima_hash->algo,
iint->ima_hash->digest, &hash.hdr);
iint->ima_hash->digest,
container_of(&hash.hdr,
struct ima_digest_data, hdr));
if (rc) {
*cause = "sigv3-hashing-error";
*status = INTEGRITY_FAIL;