/*
* evm_inode_init_security - initializes security.evm
*/
int evm_inode_init_security(struct inode *inode,
const struct xattr *lsm_xattr,
struct xattr *evm_xattr)
{
struct evm_ima_xattr_data *xattr_data;
int rc;
if (!evm_initialized || !evm_protected_xattr(lsm_xattr->name))
return 0;
xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS);
if (!xattr_data)
return -ENOMEM;
xattr_data->type = EVM_XATTR_HMAC;
rc = evm_init_hmac(inode, lsm_xattr, xattr_data->digest);
if (rc < 0)
goto out;
evm_xattr->value = xattr_data;
evm_xattr->value_len = sizeof(*xattr_data);
evm_xattr->name = kstrdup(XATTR_EVM_SUFFIX, GFP_NOFS);
return 0;
out:
kfree(xattr_data);
return rc;
}
/**
* evm_inode_post_removexattr - update 'security.evm' after removing the xattr
* @dentry: pointer to the affected dentry
* @xattr_name: pointer to the affected extended attribute name
*
* Update the HMAC stored in 'security.evm' to reflect removal of the xattr.
*
* No need to take the i_mutex lock here, as this function is called from
* vfs_removexattr() which takes the i_mutex.
*/
void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
{
if (!evm_initialized || !evm_protected_xattr(xattr_name))
return;
evm_update_evmxattr(dentry, xattr_name, NULL, 0);
}
/*
* evm_protect_xattr - protect the EVM extended attribute
*
* Prevent security.evm from being modified or removed without the
* necessary permissions or when the existing value is invalid.
*
* The posix xattr acls are 'system' prefixed, which normally would not
* affect security.evm. An interesting side affect of writing posix xattr
* acls is their modifying of the i_mode, which is included in security.evm.
* For posix xattr acls only, permit security.evm, even if it currently
* doesn't exist, to be updated.
*/
static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
enum integrity_status evm_status;
if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
} else if (!evm_protected_xattr(xattr_name)) {
if (!posix_xattr_acl(xattr_name))
return 0;
evm_status = evm_verify_current_integrity(dentry);
if ((evm_status == INTEGRITY_PASS) ||
(evm_status == INTEGRITY_NOXATTRS))
return 0;
goto out;
}
evm_status = evm_verify_current_integrity(dentry);
out:
if (evm_status != INTEGRITY_PASS)
integrity_audit_msg(AUDIT_INTEGRITY_METADATA, dentry->d_inode,
dentry->d_name.name, "appraise_metadata",
integrity_status_msg[evm_status],
-EPERM, 0);
return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
}
/**
* evm_inode_post_setxattr - update 'security.evm' to reflect the changes
* @dentry: pointer to the affected dentry
* @xattr_name: pointer to the affected extended attribute name
* @xattr_value: pointer to the new extended attribute value
* @xattr_value_len: pointer to the new extended attribute value length
*
* Update the HMAC stored in 'security.evm' to reflect the change.
*
* No need to take the i_mutex lock here, as this function is called from
* __vfs_setxattr_noperm(). The caller of which has taken the inode's
* i_mutex lock.
*/
void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
if (!evm_initialized || (!evm_protected_xattr(xattr_name)
&& !posix_xattr_acl(xattr_name)))
return;
evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len);
}
/**
* evm_inode_post_removexattr - update 'security.evm' after removing the xattr
* @dentry: pointer to the affected dentry
* @xattr_name: pointer to the affected extended attribute name
*
* Update the HMAC stored in 'security.evm' to reflect removal of the xattr.
*
* No need to take the i_mutex lock here, as this function is called from
* vfs_removexattr() which takes the i_mutex.
*/
void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
{
if (!evm_key_loaded() || !evm_protected_xattr(xattr_name))
return;
evm_reset_status(dentry->d_inode);
evm_update_evmxattr(dentry, xattr_name, NULL, 0);
}
/**
* evm_inode_post_removexattr - update 'security.evm' after removing the xattr
* @dentry: pointer to the affected dentry
* @xattr_name: pointer to the affected extended attribute name
*
* Update the HMAC stored in 'security.evm' to reflect removal of the xattr.
*/
void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
{
struct inode *inode = dentry->d_inode;
if (!evm_initialized || !evm_protected_xattr(xattr_name))
return;
mutex_lock(&inode->i_mutex);
evm_update_evmxattr(dentry, xattr_name, NULL, 0);
mutex_unlock(&inode->i_mutex);
}
/**
* evm_inode_post_setxattr - update 'security.evm' to reflect the changes
* @dentry: pointer to the affected dentry
* @xattr_name: pointer to the affected extended attribute name
* @xattr_value: pointer to the new extended attribute value
* @xattr_value_len: pointer to the new extended attribute value length
*
* Update the HMAC stored in 'security.evm' to reflect the change.
*
* No need to take the i_mutex lock here, as this function is called from
* __vfs_setxattr_noperm(). The caller of which has taken the inode's
* i_mutex lock.
*/
void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
if (!evm_key_loaded() || (!evm_protected_xattr(xattr_name)
&& !posix_xattr_acl(xattr_name)))
return;
evm_reset_status(dentry->d_inode);
evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len);
}
/**
* evm_verifyxattr - verify the integrity of the requested xattr
* @dentry: object of the verify xattr
* @xattr_name: requested xattr
* @xattr_value: requested xattr value
* @xattr_value_len: requested xattr value length
*
* Calculate the HMAC for the given dentry and verify it against the stored
* security.evm xattr. For performance, use the xattr value and length
* previously retrieved to calculate the HMAC.
*
* Returns the xattr integrity status.
*
* This function requires the caller to lock the inode's i_mutex before it
* is executed.
*/
enum integrity_status evm_verifyxattr(struct dentry *dentry,
const char *xattr_name,
void *xattr_value, size_t xattr_value_len,
struct integrity_iint_cache *iint)
{
if (!evm_initialized || !evm_protected_xattr(xattr_name))
return INTEGRITY_UNKNOWN;
if (!iint) {
iint = integrity_iint_find(dentry->d_inode);
if (!iint)
return INTEGRITY_UNKNOWN;
}
return evm_verify_hmac(dentry, xattr_name, xattr_value,
xattr_value_len, iint);
}
/*
* evm_protect_xattr - protect the EVM extended attribute
*
* Prevent security.evm from being modified or removed without the
* necessary permissions or when the existing value is invalid.
*
* The posix xattr acls are 'system' prefixed, which normally would not
* affect security.evm. An interesting side affect of writing posix xattr
* acls is their modifying of the i_mode, which is included in security.evm.
* For posix xattr acls only, permit security.evm, even if it currently
* doesn't exist, to be updated unless the EVM signature is immutable.
*/
static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
enum integrity_status evm_status;
if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
} else if (!evm_protected_xattr(xattr_name)) {
if (!posix_xattr_acl(xattr_name))
return 0;
evm_status = evm_verify_current_integrity(dentry);
if ((evm_status == INTEGRITY_PASS) ||
(evm_status == INTEGRITY_NOXATTRS))
return 0;
goto out;
}
evm_status = evm_verify_current_integrity(dentry);
if (evm_status == INTEGRITY_NOXATTRS) {
struct integrity_iint_cache *iint;
iint = integrity_iint_find(d_backing_inode(dentry));
if (iint && (iint->flags & IMA_NEW_FILE))
return 0;
/* exception for pseudo filesystems */
if (dentry->d_sb->s_magic == TMPFS_MAGIC
|| dentry->d_sb->s_magic == SYSFS_MAGIC)
return 0;
integrity_audit_msg(AUDIT_INTEGRITY_METADATA,
dentry->d_inode, dentry->d_name.name,
"update_metadata",
integrity_status_msg[evm_status],
-EPERM, 0);
}
out:
if (evm_status != INTEGRITY_PASS)
integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
dentry->d_name.name, "appraise_metadata",
integrity_status_msg[evm_status],
-EPERM, 0);
return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
}
/*
* evm_protect_xattr - protect the EVM extended attribute
*
* Prevent security.evm from being modified or removed without the
* necessary permissions or when the existing value is invalid.
*
* The posix xattr acls are 'system' prefixed, which normally would not
* affect security.evm. An interesting side affect of writing posix xattr
* acls is their modifying of the i_mode, which is included in security.evm.
* For posix xattr acls only, permit security.evm, even if it currently
* doesn't exist, to be updated.
*/
static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
enum integrity_status evm_status;
if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
} else if (!evm_protected_xattr(xattr_name)) {
if (!posix_xattr_acl(xattr_name))
return 0;
evm_status = evm_verify_current_integrity(dentry);
if ((evm_status == INTEGRITY_PASS) ||
(evm_status == INTEGRITY_NOXATTRS))
return 0;
return -EPERM;
}
evm_status = evm_verify_current_integrity(dentry);
return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
}
