![Kees Cook](/assets/img/avatar_default.png)
There are a few places in the kernel where LSMs would like to have visibility into the contents of a kernel buffer that has been loaded or read. While security_kernel_post_read_file() (which includes the buffer) exists as a pairing for security_kernel_read_file(), no such hook exists to pair with security_kernel_load_data(). Earlier proposals for just using security_kernel_post_read_file() with a NULL file argument were rejected (i.e. "file" should always be valid for the security_..._file hooks, but it appears at least one case was left in the kernel during earlier refactoring. (This will be fixed in a subsequent patch.) Since not all cases of security_kernel_load_data() can have a single contiguous buffer made available to the LSM hook (e.g. kexec image segments are separately loaded), there needs to be a way for the LSM to reason about its expectations of the hook coverage. In order to handle this, add a "contents" argument to the "kernel_load_data" hook that indicates if the newly added "kernel_post_load_data" hook will be called with the full contents once loaded. That way, LSMs requiring full contents can choose to unilaterally reject "kernel_load_data" with contents=false (which is effectively the existing hook coverage), but when contents=true they can allow it and later evaluate the "kernel_post_load_data" hook once the buffer is loaded. With this change, LSMs can gain coverage over non-file-backed data loads (e.g. init_module(2) and firmware userspace helper), which will happen in subsequent patches. Additionally prepare IMA to start processing these cases. Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: KP Singh <kpsingh@google.com> Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
181 lines
4.5 KiB
C
181 lines
4.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2008 IBM Corporation
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* Author: Mimi Zohar <zohar@us.ibm.com>
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*/
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#ifndef _LINUX_IMA_H
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#define _LINUX_IMA_H
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#include <linux/kernel_read_file.h>
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#include <linux/fs.h>
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#include <linux/security.h>
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#include <linux/kexec.h>
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struct linux_binprm;
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#ifdef CONFIG_IMA
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extern int ima_bprm_check(struct linux_binprm *bprm);
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extern int ima_file_check(struct file *file, int mask);
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extern void ima_post_create_tmpfile(struct inode *inode);
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extern void ima_file_free(struct file *file);
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extern int ima_file_mmap(struct file *file, unsigned long prot);
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extern int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot);
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extern int ima_load_data(enum kernel_load_data_id id, bool contents);
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extern int ima_post_load_data(char *buf, loff_t size,
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enum kernel_load_data_id id, char *description);
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extern int ima_read_file(struct file *file, enum kernel_read_file_id id);
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extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
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enum kernel_read_file_id id);
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extern void ima_post_path_mknod(struct dentry *dentry);
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extern int ima_file_hash(struct file *file, char *buf, size_t buf_size);
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extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size);
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#ifdef CONFIG_IMA_KEXEC
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extern void ima_add_kexec_buffer(struct kimage *image);
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#endif
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#ifdef CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT
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extern bool arch_ima_get_secureboot(void);
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extern const char * const *arch_get_ima_policy(void);
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#else
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static inline bool arch_ima_get_secureboot(void)
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{
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return false;
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}
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static inline const char * const *arch_get_ima_policy(void)
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{
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return NULL;
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}
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#endif
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#else
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static inline int ima_bprm_check(struct linux_binprm *bprm)
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{
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return 0;
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}
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static inline int ima_file_check(struct file *file, int mask)
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{
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return 0;
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}
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static inline void ima_post_create_tmpfile(struct inode *inode)
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{
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}
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static inline void ima_file_free(struct file *file)
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{
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return;
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}
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static inline int ima_file_mmap(struct file *file, unsigned long prot)
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{
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return 0;
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}
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static inline int ima_file_mprotect(struct vm_area_struct *vma,
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unsigned long prot)
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{
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return 0;
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}
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static inline int ima_load_data(enum kernel_load_data_id id, bool contents)
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{
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return 0;
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}
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static inline int ima_post_load_data(char *buf, loff_t size,
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enum kernel_load_data_id id,
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char *description)
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{
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return 0;
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}
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static inline int ima_read_file(struct file *file, enum kernel_read_file_id id)
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{
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return 0;
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}
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static inline int ima_post_read_file(struct file *file, void *buf, loff_t size,
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enum kernel_read_file_id id)
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{
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return 0;
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}
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static inline void ima_post_path_mknod(struct dentry *dentry)
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{
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return;
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}
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static inline int ima_file_hash(struct file *file, char *buf, size_t buf_size)
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{
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return -EOPNOTSUPP;
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}
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static inline void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) {}
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#endif /* CONFIG_IMA */
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#ifndef CONFIG_IMA_KEXEC
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struct kimage;
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static inline void ima_add_kexec_buffer(struct kimage *image)
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{}
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#endif
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#ifdef CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS
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extern void ima_post_key_create_or_update(struct key *keyring,
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struct key *key,
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const void *payload, size_t plen,
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unsigned long flags, bool create);
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#else
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static inline void ima_post_key_create_or_update(struct key *keyring,
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struct key *key,
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const void *payload,
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size_t plen,
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unsigned long flags,
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bool create) {}
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#endif /* CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS */
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#ifdef CONFIG_IMA_APPRAISE
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extern bool is_ima_appraise_enabled(void);
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extern void ima_inode_post_setattr(struct dentry *dentry);
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extern int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
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const void *xattr_value, size_t xattr_value_len);
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extern int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name);
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#else
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static inline bool is_ima_appraise_enabled(void)
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{
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return 0;
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}
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static inline void ima_inode_post_setattr(struct dentry *dentry)
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{
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return;
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}
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static inline int ima_inode_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 0;
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}
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static inline int ima_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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#endif /* CONFIG_IMA_APPRAISE */
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#if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
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extern bool ima_appraise_signature(enum kernel_read_file_id func);
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#else
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static inline bool ima_appraise_signature(enum kernel_read_file_id func)
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{
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return false;
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}
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#endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */
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#endif /* _LINUX_IMA_H */
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