Commit 0496fc9c authored Jan 20, 2026 by Roberto Sassu Committed by Mimi Zohar Jan 23, 2026

evm: Use ordered xattrs list to calculate HMAC in evm_init_hmac()

Commit 8e5d9f91 ("smack: deduplicate xattr setting in
smack_inode_init_security()") introduced xattr_dupval() to simplify setting
the xattrs to be provided by the SMACK LSM on inode creation, in the
smack_inode_init_security().

Unfortunately, moving lsm_get_xattr_slot() caused the SMACK64TRANSMUTE
xattr be added in the array of new xattrs before SMACK64. This causes the
HMAC of xattrs calculated by evm_init_hmac() for new files to diverge from
the one calculated by both evm_calc_hmac_or_hash() and evmctl.

evm_init_hmac() calculates the HMAC of the xattrs of new files based on the
order LSMs provide them, while evm_calc_hmac_or_hash() and evmctl calculate
the HMAC based on an ordered xattrs list.

Fix the issue by making evm_init_hmac() calculate the HMAC of new files
based on the ordered xattrs list too.

Fixes: 8e5d9f91 ("smack: deduplicate xattr setting in smack_inode_init_security()")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

parent 377cae98

security/integrity/evm/evm_crypto.c

+10 −4

Original line number	Diff line number	Diff line
		@@ -401,6 +401,7 @@ int evm_init_hmac(struct inode inode, const struct xattr xattrs,
		{
		struct shash_desc *desc;
		const struct xattr *xattr;
		struct xattr_list *xattr_entry;

		desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
		if (IS_ERR(desc)) {
		@@ -408,11 +409,16 @@ int evm_init_hmac(struct inode inode, const struct xattr xattrs,
		return PTR_ERR(desc);
		}

		list_for_each_entry_lockless(xattr_entry, &evm_config_xattrnames,
		list) {
		for (xattr = xattrs; xattr->name; xattr++) {
		if (!evm_protected_xattr(xattr->name))
		if (strcmp(xattr_entry->name +
		XATTR_SECURITY_PREFIX_LEN, xattr->name) != 0)
		continue;

		crypto_shash_update(desc, xattr->value, xattr->value_len);
		crypto_shash_update(desc, xattr->value,
		xattr->value_len);
		}
		}

		hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);