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linux/security/ipe/hooks.h

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ipe: add LSM hooks on execution and kernel read IPE's initial goal is to control both execution and the loading of kernel modules based on the system's definition of trust. It accomplishes this by plugging into the security hooks for bprm_check_security, file_mprotect, mmap_file, kernel_load_data, and kernel_read_data. Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-08-02 23:08:18 -07:00
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
*/
#ifndef _IPE_HOOKS_H
#define _IPE_HOOKS_H
#include <linux/fs.h>
#include <linux/binfmts.h>
#include <linux/security.h>
ipe: add support for dm-verity as a trust provider Allows author of IPE policy to indicate trust for a singular dm-verity volume, identified by roothash, through "dmverity_roothash" and all signed and validated dm-verity volumes, through "dmverity_signature". Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> [PM: fixed some line length issues in the comments] Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-08-02 23:08:27 -07:00
#include <linux/blk_types.h>
ipe: enable support for fs-verity as a trust provider Enable IPE policy authors to indicate trust for a singular fsverity file, identified by the digest information, through "fsverity_digest" and all files using valid fsverity builtin signatures via "fsverity_signature". This enables file-level integrity claims to be expressed in IPE, allowing individual files to be authorized, giving some flexibility for policy authors. Such file-level claims are important to be expressed for enforcing the integrity of packages, as well as address some of the scalability issues in a sole dm-verity based solution (# of loop back devices, etc). This solution cannot be done in userspace as the minimum threat that IPE should mitigate is an attacker downloads malicious payload with all required dependencies. These dependencies can lack the userspace check, bypassing the protection entirely. A similar attack succeeds if the userspace component is replaced with a version that does not perform the check. As a result, this can only be done in the common entry point - the kernel. Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-08-02 23:08:30 -07:00
#include <linux/fsverity.h>
ipe: add LSM hooks on execution and kernel read IPE's initial goal is to control both execution and the loading of kernel modules based on the system's definition of trust. It accomplishes this by plugging into the security hooks for bprm_check_security, file_mprotect, mmap_file, kernel_load_data, and kernel_read_data. Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-08-02 23:08:18 -07:00
audit,ipe: add IPE auditing support Users of IPE require a way to identify when and why an operation fails, allowing them to both respond to violations of policy and be notified of potentially malicious actions on their systems with respect to IPE itself. This patch introduces 3 new audit events. AUDIT_IPE_ACCESS(1420) indicates the result of an IPE policy evaluation of a resource. AUDIT_IPE_CONFIG_CHANGE(1421) indicates the current active IPE policy has been changed to another loaded policy. AUDIT_IPE_POLICY_LOAD(1422) indicates a new IPE policy has been loaded into the kernel. This patch also adds support for success auditing, allowing users to identify why an allow decision was made for a resource. However, it is recommended to use this option with caution, as it is quite noisy. Here are some examples of the new audit record types: AUDIT_IPE_ACCESS(1420): audit: AUDIT1420 ipe_op=EXECUTE ipe_hook=BPRM_CHECK enforcing=1 pid=297 comm="sh" path="/root/vol/bin/hello" dev="tmpfs" ino=3897 rule="op=EXECUTE boot_verified=TRUE action=ALLOW" audit: AUDIT1420 ipe_op=EXECUTE ipe_hook=BPRM_CHECK enforcing=1 pid=299 comm="sh" path="/mnt/ipe/bin/hello" dev="dm-0" ino=2 rule="DEFAULT action=DENY" audit: AUDIT1420 ipe_op=EXECUTE ipe_hook=BPRM_CHECK enforcing=1 pid=300 path="/tmp/tmpdp2h1lub/deny/bin/hello" dev="tmpfs" ino=131 rule="DEFAULT action=DENY" The above three records were generated when the active IPE policy only allows binaries from the initramfs to run. The three identical `hello` binary were placed at different locations, only the first hello from the rootfs(initramfs) was allowed. Field ipe_op followed by the IPE operation name associated with the log. Field ipe_hook followed by the name of the LSM hook that triggered the IPE event. Field enforcing followed by the enforcement state of IPE. (it will be introduced in the next commit) Field pid followed by the pid of the process that triggered the IPE event. Field comm followed by the command line program name of the process that triggered the IPE event. Field path followed by the file's path name. Field dev followed by the device name as found in /dev where the file is from. Note that for device mappers it will use the name `dm-X` instead of the name in /dev/mapper. For a file in a temp file system, which is not from a device, it will use `tmpfs` for the field. The implementation of this part is following another existing use case LSM_AUDIT_DATA_INODE in security/lsm_audit.c Field ino followed by the file's inode number. Field rule followed by the IPE rule made the access decision. The whole rule must be audited because the decision is based on the combination of all property conditions in the rule. Along with the syscall audit event, user can know why a blocked happened. For example: audit: AUDIT1420 ipe_op=EXECUTE ipe_hook=BPRM_CHECK enforcing=1 pid=2138 comm="bash" path="/mnt/ipe/bin/hello" dev="dm-0" ino=2 rule="DEFAULT action=DENY" audit[1956]: SYSCALL arch=c000003e syscall=59 success=no exit=-13 a0=556790138df0 a1=556790135390 a2=5567901338b0 a3=ab2a41a67f4f1f4e items=1 ppid=147 pid=1956 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=4294967295 comm="bash" exe="/usr/bin/bash" key=(null) The above two records showed bash used execve to run "hello" and got blocked by IPE. Note that the IPE records are always prior to a SYSCALL record. AUDIT_IPE_CONFIG_CHANGE(1421): audit: AUDIT1421 old_active_pol_name="Allow_All" old_active_pol_version=0.0.0 old_policy_digest=sha256:E3B0C44298FC1C149AFBF4C8996FB92427AE41E4649 new_active_pol_name="boot_verified" new_active_pol_version=0.0.0 new_policy_digest=sha256:820EEA5B40CA42B51F68962354BA083122A20BB846F auid=4294967295 ses=4294967295 lsm=ipe res=1 The above record showed the current IPE active policy switch from `Allow_All` to `boot_verified` along with the version and the hash digest of the two policies. Note IPE can only have one policy active at a time, all access decision evaluation is based on the current active policy. The normal procedure to deploy a policy is loading the policy to deploy into the kernel first, then switch the active policy to it. AUDIT_IPE_POLICY_LOAD(1422): audit: AUDIT1422 policy_name="boot_verified" policy_version=0.0.0 policy_digest=sha256:820EEA5B40CA42B51F68962354BA083122A20BB846F2676 auid=4294967295 ses=4294967295 lsm=ipe res=1 The above record showed a new policy has been loaded into the kernel with the policy name, policy version and policy hash. Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> [PM: subject line tweak] Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-08-02 23:08:23 -07:00
enum ipe_hook_type {
IPE_HOOK_BPRM_CHECK = 0,
IPE_HOOK_MMAP,
IPE_HOOK_MPROTECT,
IPE_HOOK_KERNEL_READ,
IPE_HOOK_KERNEL_LOAD,
__IPE_HOOK_MAX
};
#define IPE_HOOK_INVALID __IPE_HOOK_MAX
ipe: add LSM hooks on execution and kernel read IPE's initial goal is to control both execution and the loading of kernel modules based on the system's definition of trust. It accomplishes this by plugging into the security hooks for bprm_check_security, file_mprotect, mmap_file, kernel_load_data, and kernel_read_data. Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-08-02 23:08:18 -07:00
int ipe_bprm_check_security(struct linux_binprm *bprm);
int ipe_mmap_file(struct file *f, unsigned long reqprot, unsigned long prot,
unsigned long flags);
int ipe_file_mprotect(struct vm_area_struct *vma, unsigned long reqprot,
unsigned long prot);
int ipe_kernel_read_file(struct file *file, enum kernel_read_file_id id,
bool contents);
int ipe_kernel_load_data(enum kernel_load_data_id id, bool contents);
ipe: introduce 'boot_verified' as a trust provider IPE is designed to provide system level trust guarantees, this usually implies that trust starts from bootup with a hardware root of trust, which validates the bootloader. After this, the bootloader verifies the kernel and the initramfs. As there's no currently supported integrity method for initramfs, and it's typically already verified by the bootloader. This patch introduces a new IPE property `boot_verified` which allows author of IPE policy to indicate trust for files from initramfs. The implementation of this feature utilizes the newly added `initramfs_populated` hook. This hook marks the superblock of the rootfs after the initramfs has been unpacked into it. Before mounting the real rootfs on top of the initramfs, initramfs script will recursively remove all files and directories on the initramfs. This is typically implemented by using switch_root(8) (https://man7.org/linux/man-pages/man8/switch_root.8.html). Therefore the initramfs will be empty and not accessible after the real rootfs takes over. It is advised to switch to a different policy that doesn't rely on the `boot_verified` property after this point. This ensures that the trust policies remain relevant and effective throughout the system's operation. Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-08-02 23:08:20 -07:00
void ipe_unpack_initramfs(void);
ipe: add support for dm-verity as a trust provider Allows author of IPE policy to indicate trust for a singular dm-verity volume, identified by roothash, through "dmverity_roothash" and all signed and validated dm-verity volumes, through "dmverity_signature". Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> [PM: fixed some line length issues in the comments] Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-08-02 23:08:27 -07:00
#ifdef CONFIG_IPE_PROP_DM_VERITY
void ipe_bdev_free_security(struct block_device *bdev);
int ipe_bdev_setintegrity(struct block_device *bdev, enum lsm_integrity_type type,
const void *value, size_t len);
#endif /* CONFIG_IPE_PROP_DM_VERITY */
ipe: enable support for fs-verity as a trust provider Enable IPE policy authors to indicate trust for a singular fsverity file, identified by the digest information, through "fsverity_digest" and all files using valid fsverity builtin signatures via "fsverity_signature". This enables file-level integrity claims to be expressed in IPE, allowing individual files to be authorized, giving some flexibility for policy authors. Such file-level claims are important to be expressed for enforcing the integrity of packages, as well as address some of the scalability issues in a sole dm-verity based solution (# of loop back devices, etc). This solution cannot be done in userspace as the minimum threat that IPE should mitigate is an attacker downloads malicious payload with all required dependencies. These dependencies can lack the userspace check, bypassing the protection entirely. A similar attack succeeds if the userspace component is replaced with a version that does not perform the check. As a result, this can only be done in the common entry point - the kernel. Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-08-02 23:08:30 -07:00
#ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG
int ipe_inode_setintegrity(const struct inode *inode, enum lsm_integrity_type type,
const void *value, size_t size);
#endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
ipe: add LSM hooks on execution and kernel read IPE's initial goal is to control both execution and the loading of kernel modules based on the system's definition of trust. It accomplishes this by plugging into the security hooks for bprm_check_security, file_mprotect, mmap_file, kernel_load_data, and kernel_read_data. Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-08-02 23:08:18 -07:00
#endif /* _IPE_HOOKS_H */
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