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0e363cf3fa
Before this change we used to take a shortcut and place the actual
values that would be written to inode->i_{g,u}id into struct iattr. This
had the advantage that we moved idmappings mostly out of the picture
early on but it made reasoning about changes more difficult than it
should be.
The filesystem was never explicitly told that it dealt with an idmapped
mount. The transition to the value that needed to be stored in
inode->i_{g,u}id appeared way too early and increased the probability of
bugs in various codepaths.
We know place the same value in struct iattr no matter if this is an
idmapped mount or not. The vfs will only deal with type safe
vfs{g,u}id_t. This makes it massively safer to perform permission checks
as the type will tell us what checks we need to perform and what helpers
we need to use.
Adapt the security_inode_setattr() helper to pass down the mount's
idmapping to account for that change.
Link: https://lore.kernel.org/r/20220621141454.2914719-8-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
136 lines
3.5 KiB
C
136 lines
3.5 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 user_namespace *mnt_userns,
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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 user_namespace *mnt_userns,
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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 user_namespace *mnt_userns,
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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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extern int evm_protected_xattr_if_enabled(const char *req_xattr_name);
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extern int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
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int buffer_size, char type,
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bool canonical_fmt);
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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 user_namespace *mnt_userns,
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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 user_namespace *mnt_userns,
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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 user_namespace *mnt_userns,
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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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static inline int evm_protected_xattr_if_enabled(const char *req_xattr_name)
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{
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return false;
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}
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static inline int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
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int buffer_size, char type,
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bool canonical_fmt)
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{
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return -EOPNOTSUPP;
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}
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#endif /* CONFIG_EVM */
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#endif /* LINUX_EVM_H */
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