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e3ccfe1ad7
When EVM_ALLOW_METADATA_WRITES is set, EVM allows any operation on metadata. Its main purpose is to allow users to freely set metadata when it is protected by a portable signature, until an HMAC key is loaded. However, callers of evm_verifyxattr() are not notified about metadata changes and continue to rely on the last status returned by the function. For example IMA, since it caches the appraisal result, will not call again evm_verifyxattr() until the appraisal flags are cleared, and will grant access to the file even if there was a metadata operation that made the portable signature invalid. This patch introduces evm_revalidate_status(), which callers of evm_verifyxattr() can use in their xattr hooks to determine whether re-validation is necessary and to do the proper actions. IMA calls it in its xattr hooks to reset the appraisal flags, so that the EVM status is re-evaluated after a metadata operation. Lastly, this patch also adds a call to evm_reset_status() in evm_inode_post_setattr() to invalidate the cached EVM status after a setattr operation. Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
114 lines
2.8 KiB
C
114 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* evm.h
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*
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* Copyright (c) 2009 IBM Corporation
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* Author: Mimi Zohar <zohar@us.ibm.com>
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*/
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#ifndef _LINUX_EVM_H
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#define _LINUX_EVM_H
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#include <linux/integrity.h>
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#include <linux/xattr.h>
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struct integrity_iint_cache;
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#ifdef CONFIG_EVM
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extern int evm_set_key(void *key, size_t keylen);
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extern enum integrity_status evm_verifyxattr(struct dentry *dentry,
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const char *xattr_name,
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void *xattr_value,
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size_t xattr_value_len,
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struct integrity_iint_cache *iint);
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extern int evm_inode_setattr(struct dentry *dentry, struct iattr *attr);
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extern void evm_inode_post_setattr(struct dentry *dentry, int ia_valid);
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extern int evm_inode_setxattr(struct dentry *dentry, const char *name,
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const void *value, size_t size);
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extern void evm_inode_post_setxattr(struct dentry *dentry,
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const char *xattr_name,
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const void *xattr_value,
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size_t xattr_value_len);
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extern int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name);
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extern void evm_inode_post_removexattr(struct dentry *dentry,
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const char *xattr_name);
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extern int evm_inode_init_security(struct inode *inode,
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const struct xattr *xattr_array,
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struct xattr *evm);
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extern bool evm_revalidate_status(const char *xattr_name);
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#ifdef CONFIG_FS_POSIX_ACL
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extern int posix_xattr_acl(const char *xattrname);
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#else
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static inline int posix_xattr_acl(const char *xattrname)
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{
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return 0;
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}
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#endif
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#else
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static inline int evm_set_key(void *key, size_t keylen)
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{
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return -EOPNOTSUPP;
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}
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#ifdef CONFIG_INTEGRITY
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static inline enum integrity_status evm_verifyxattr(struct dentry *dentry,
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const char *xattr_name,
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void *xattr_value,
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size_t xattr_value_len,
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struct integrity_iint_cache *iint)
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{
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return INTEGRITY_UNKNOWN;
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}
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#endif
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static inline int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
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{
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return 0;
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}
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static inline void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
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{
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return;
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}
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static inline int evm_inode_setxattr(struct dentry *dentry, const char *name,
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const void *value, size_t size)
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{
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return 0;
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}
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static inline void evm_inode_post_setxattr(struct dentry *dentry,
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const char *xattr_name,
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const void *xattr_value,
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size_t xattr_value_len)
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{
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return;
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}
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static inline int evm_inode_removexattr(struct dentry *dentry,
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const char *xattr_name)
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{
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return 0;
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}
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static inline void evm_inode_post_removexattr(struct dentry *dentry,
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const char *xattr_name)
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{
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return;
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}
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static inline int evm_inode_init_security(struct inode *inode,
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const struct xattr *xattr_array,
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struct xattr *evm)
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{
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return 0;
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}
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static inline bool evm_revalidate_status(const char *xattr_name)
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{
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return false;
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}
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#endif /* CONFIG_EVM */
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#endif /* LINUX_EVM_H */
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