Re: [PATCH][next] integrity: Use static_assert() to check struct sizes
From: Roberto Sassu <hidden>
Date: 2024-08-16 12:46:56
Also in:
linux-hardening, linux-integrity, lkml
On Thu, 2024-08-08 at 16:04 -0600, Gustavo A. R. Silva wrote:
Commit 38aa3f5ac6d2 ("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.Looks good to me. Tested-by: Roberto Sassu <roberto.sassu@huawei.com> Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com> Thanks Roberto
quoted hunk ↗ jump to hunk
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- security/integrity/integrity.h | 4 ++++ 1 file changed, 4 insertions(+)diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index 660f76cb69d3..c2c2da691123 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h@@ -37,6 +37,8 @@ struct evm_ima_xattr_data { ); u8 data[]; } __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. */ struct evm_xattr {@@ -65,6 +67,8 @@ struct ima_digest_data { ); u8 digest[]; } __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