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integrity: Use static_assert() to check struct sizes

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Commit 38aa3f5ac6 ("integrity: Avoid -Wflex-array-member-not-at-end
warnings") introduced tagged `struct evm_ima_xattr_data_hdr` and
`struct ima_digest_data_hdr`. We want to ensure that when new members
need to be added to the flexible structures, they are always included
within these tagged structs.

So, we use `static_assert()` to ensure that the memory layout for
both the flexible structure and the tagged struct is the same after
any changes.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Tested-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This commit is contained in:
Gustavo A. R. Silva 2024-08-08 16:04:59 -06:00 committed by Mimi Zohar
parent 699ae62419
commit 08ae3e5f5f
1 changed files with 4 additions and 0 deletions
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4
security/integrity/integrity.h
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@ -37,6 +37,8 @@ struct evm_ima_xattr_data {
); );
u8 data[]; u8 data[];
} __packed; } __packed;
static_assert(offsetof(struct evm_ima_xattr_data, data) == sizeof(struct evm_ima_xattr_data_hdr),
"struct member likely outside of __struct_group()");
/* Only used in the EVM HMAC code. */ /* Only used in the EVM HMAC code. */
struct evm_xattr { struct evm_xattr {
@ -65,6 +67,8 @@ struct ima_digest_data {
); );
u8 digest[]; u8 digest[];
} __packed; } __packed;
static_assert(offsetof(struct ima_digest_data, digest) == sizeof(struct ima_digest_data_hdr),
"struct member likely outside of __struct_group()");
/* /*
* Instead of wrapping the ima_digest_data struct inside a local structure * Instead of wrapping the ima_digest_data struct inside a local structure