linux-stable/include/linux/evm.h
Roberto Sassu 8c7a703ec9 evm: Verify portable signatures against all protected xattrs
Currently, the evm_config_default_xattrnames array contains xattr names
only related to LSMs which are enabled in the kernel configuration.
However, EVM portable signatures do not depend on local information and a
vendor might include in the signature calculation xattrs that are not
enabled in the target platform.

Just including all xattrs names in evm_config_default_xattrnames is not a
safe approach, because a target system might have already calculated
signatures or HMACs based only on the enabled xattrs. After applying this
patch, EVM would verify those signatures and HMACs with all xattrs instead.
The non-enabled ones, which could possibly exist, would cause a
verification error.

Thus, this patch adds a new field named enabled to the xattr_list
structure, which is set to true if the LSM associated to a given xattr name
is enabled in the kernel configuration. The non-enabled xattrs are taken
into account only in evm_calc_hmac_or_hash(), if the passed security.evm
type is EVM_XATTR_PORTABLE_DIGSIG.

The new function evm_protected_xattr_if_enabled() has been defined so that
IMA can include all protected xattrs and not only the enabled ones in the
measurement list, if the new template fields xattrnames, xattrlengths or
xattrvalues have been included in the template format.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-06-01 15:17:31 -04:00

124 lines
3.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
/*
* evm.h
*
* Copyright (c) 2009 IBM Corporation
* Author: Mimi Zohar <zohar@us.ibm.com>
*/
#ifndef _LINUX_EVM_H
#define _LINUX_EVM_H
#include <linux/integrity.h>
#include <linux/xattr.h>
struct integrity_iint_cache;
#ifdef CONFIG_EVM
extern int evm_set_key(void *key, size_t keylen);
extern 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);
extern int evm_inode_setattr(struct dentry *dentry, struct iattr *attr);
extern void evm_inode_post_setattr(struct dentry *dentry, int ia_valid);
extern int evm_inode_setxattr(struct user_namespace *mnt_userns,
struct dentry *dentry, const char *name,
const void *value, size_t size);
extern void evm_inode_post_setxattr(struct dentry *dentry,
const char *xattr_name,
const void *xattr_value,
size_t xattr_value_len);
extern int evm_inode_removexattr(struct user_namespace *mnt_userns,
struct dentry *dentry, const char *xattr_name);
extern void evm_inode_post_removexattr(struct dentry *dentry,
const char *xattr_name);
extern int evm_inode_init_security(struct inode *inode,
const struct xattr *xattr_array,
struct xattr *evm);
extern bool evm_revalidate_status(const char *xattr_name);
extern int evm_protected_xattr_if_enabled(const char *req_xattr_name);
#ifdef CONFIG_FS_POSIX_ACL
extern int posix_xattr_acl(const char *xattrname);
#else
static inline int posix_xattr_acl(const char *xattrname)
{
return 0;
}
#endif
#else
static inline int evm_set_key(void *key, size_t keylen)
{
return -EOPNOTSUPP;
}
#ifdef CONFIG_INTEGRITY
static inline 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)
{
return INTEGRITY_UNKNOWN;
}
#endif
static inline int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
{
return 0;
}
static inline void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
{
return;
}
static inline int evm_inode_setxattr(struct user_namespace *mnt_userns,
struct dentry *dentry, const char *name,
const void *value, size_t size)
{
return 0;
}
static inline void evm_inode_post_setxattr(struct dentry *dentry,
const char *xattr_name,
const void *xattr_value,
size_t xattr_value_len)
{
return;
}
static inline int evm_inode_removexattr(struct user_namespace *mnt_userns,
struct dentry *dentry,
const char *xattr_name)
{
return 0;
}
static inline void evm_inode_post_removexattr(struct dentry *dentry,
const char *xattr_name)
{
return;
}
static inline int evm_inode_init_security(struct inode *inode,
const struct xattr *xattr_array,
struct xattr *evm)
{
return 0;
}
static inline bool evm_revalidate_status(const char *xattr_name)
{
return false;
}
static inline int evm_protected_xattr_if_enabled(const char *req_xattr_name)
{
return false;
}
#endif /* CONFIG_EVM */
#endif /* LINUX_EVM_H */