/*
* evm_verify_hmac - calculate and compare the HMAC with the EVM xattr
*
* Compute the HMAC on the dentry's protected set of extended attributes
* and compare it against the stored security.evm xattr.
*
* For performance:
* - use the previoulsy retrieved xattr value and length to calculate the
* HMAC.)
* - cache the verification result in the iint, when available.
*
* Returns integrity status
*/
static enum integrity_status evm_verify_hmac(struct dentry *dentry,
const char *xattr_name,
char *xattr_value,
size_t xattr_value_len,
struct integrity_iint_cache *iint)
{
struct evm_ima_xattr_data xattr_data;
enum integrity_status evm_status = INTEGRITY_PASS;
int rc;
if (iint && iint->evm_status == INTEGRITY_PASS)
return iint->evm_status;
/* if status is not PASS, try to check again - against -ENOMEM */
rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
xattr_value_len, xattr_data.digest);
if (rc < 0) {
evm_status = (rc == -ENODATA)
? INTEGRITY_NOXATTRS : INTEGRITY_FAIL;
goto out;
}
xattr_data.type = EVM_XATTR_HMAC;
rc = vfs_xattr_cmp(dentry, XATTR_NAME_EVM, (u8 *)&xattr_data,
sizeof xattr_data, GFP_NOFS);
if (rc < 0)
evm_status = (rc == -ENODATA)
? INTEGRITY_NOLABEL : INTEGRITY_FAIL;
out:
if (iint)
iint->evm_status = evm_status;
return evm_status;
}
/*
* evm_verify_hmac - calculate and compare the HMAC with the EVM xattr
*
* Compute the HMAC on the dentry's protected set of extended attributes
* and compare it against the stored security.evm xattr.
*
* For performance:
* - use the previoulsy retrieved xattr value and length to calculate the
* HMAC.)
* - cache the verification result in the iint, when available.
*
* Returns integrity status
*/
static enum integrity_status evm_verify_hmac(struct dentry *dentry,
const char *xattr_name,
char *xattr_value,
size_t xattr_value_len,
struct integrity_iint_cache *iint)
{
struct evm_ima_xattr_data xattr_data;
enum integrity_status evm_status;
int rc;
if (iint && iint->evm_status == INTEGRITY_PASS)
return iint->evm_status;
/* if status is not PASS, try to check again - against -ENOMEM */
rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
xattr_value_len, xattr_data.digest);
if (rc < 0)
goto err_out;
xattr_data.type = EVM_XATTR_HMAC;
rc = vfs_xattr_cmp(dentry, XATTR_NAME_EVM, (u8 *)&xattr_data,
sizeof xattr_data, GFP_NOFS);
if (rc < 0)
goto err_out;
evm_status = INTEGRITY_PASS;
goto out;
err_out:
switch (rc) {
case -ENODATA: /* file not labelled */
evm_status = INTEGRITY_NOLABEL;
break;
default:
evm_status = INTEGRITY_FAIL;
}
out:
if (iint)
iint->evm_status = evm_status;
return evm_status;
}