// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
*/
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/types.h>
#include <linux/dcache.h>
#include <linux/security.h>
#include "ipe.h"
#include "policy.h"
#include "eval.h"
#include "fs.h"
#define MAX_VERSION_SIZE ARRAY_SIZE("65535.65535.65535")
/**
* ipefs_file - defines a file in securityfs.
*/
struct ipefs_file {
const char *name;
umode_t access;
const struct file_operations *fops;
};
/**
* read_pkcs7() - Read handler for "ipe/policies/$name/pkcs7".
* @f: Supplies a file structure representing the securityfs node.
* @data: Supplies a buffer passed to the write syscall.
* @len: Supplies the length of @data.
* @offset: unused.
*
* @data will be populated with the pkcs7 blob representing the policy
* on success. If the policy is unsigned (like the boot policy), this
* will return -ENOENT.
*
* Return:
* * Length of buffer written - Success
* * %-ENOENT - Policy initializing/deleted or is unsigned
*/
static ssize_t read_pkcs7(struct file *f, char __user *data,
size_t len, loff_t *offset)
{
const struct ipe_policy *p = NULL;
struct inode *root = NULL;
int rc = 0;
root = d_inode(f->f_path.dentry->d_parent);
inode_lock_shared(root);
p = (struct ipe_policy *)root->i_private;
if (!p) {
rc = -ENOENT;
goto out;
}
if (!p->pkcs7) {
rc = -ENOENT;
goto out;
}
rc = simple_read_from_buffer(data, len, offset, p->pkcs7, p->pkcs7len);
out:
inode_unlock_shared(root);
return rc;
}
/**
* read_policy() - Read handler for "ipe/policies/$name/policy".
* @f: Supplies a file structure representing the securityfs node.
* @data: Supplies a buffer passed to the write syscall.
* @len: Supplies the length of @data.
* @offset: unused.
*
* @data will be populated with the plain-text version of the policy
* on success.
*
* Return:
* * Length of buffer written - Success
* * %-ENOENT - Policy initializing/deleted
*/
static ssize_t read_policy(struct file *f, char __user *data,
size_t len, loff_t *offset)
{
const struct ipe_policy *p = NULL;
struct inode *root = NULL;
int rc = 0;
root = d_inode(f->f_path.dentry->d_parent);
inode_lock_shared(root);
p = (struct ipe_policy *)root->i_private;
if (!p) {
rc = -ENOENT;
goto out;
}
rc = simple_read_from_buffer(data, len, offset, p->text, p->textlen);
out:
inode_unlock_shared(root);
return rc;
}
/**
* read_name() - Read handler for "ipe/policies/$name/name".
* @f: Supplies a file structure representing the securityfs node.
* @data: Supplies a buffer passed to the write syscall.
* @len: Supplies the length of @data.
* @offset: unused.
*
* @data will be populated with the policy_name attribute on success.
*
* Return:
* * Length of buffer written - Success
* * %-ENOENT - Policy initializing/deleted
*/
static ssize_t read_name(struct file *f, char __user *data,
size_t len, loff_t *offset)
{
const struct ipe_policy *p = NULL;
struct inode *root = NULL;
int rc = 0;
root = d_inode(f->f_path.dentry->d_parent);
inode_lock_shared(root);
p = (struct ipe_policy *)root->i_private;
if (!p) {
rc = -ENOENT;
goto out;
}
rc = simple_read_from_buffer(data, len, offset, p->parsed->name,
strlen(p->parsed->name));
out:
inode_unlock_shared(root);
return rc;
}
/**
* read_version() - Read handler for "ipe/policies/$name/version".
* @f: Supplies a file structure representing the securityfs node.
* @data: Supplies a buffer passed to the write syscall.
* @len: Supplies the length of @data.
* @offset: unused.
*
* @data will be populated with the version string on success.
*
* Return:
* * Length of buffer written - Success
* * %-ENOENT - Policy initializing/deleted
*/
static ssize_t read_version(struct file *f, char __user *data,
size_t len, loff_t *offset)
{
char buffer[MAX_VERSION_SIZE] = { 0 };
const struct ipe_policy *p = NULL;
struct inode *root = NULL;
size_t strsize = 0;
ssize_t rc = 0;
root = d_inode(f->f_path.dentry->d_parent);
inode_lock_shared(root);
p = (struct ipe_policy *)root->i_private;
if (!p) {
rc = -ENOENT;
goto out;
}
strsize = scnprintf(buffer, ARRAY_SIZE(buffer), "%hu.%hu.%hu",
p->parsed->version.major, p->parsed->version.minor,
p->parsed->version.rev);
rc = simple_read_from_buffer(data, len, offset, buffer, strsize);
out:
inode_unlock_shared(root);
return rc;
}
/**
* setactive() - Write handler for "ipe/policies/$name/active".
* @f: Supplies a file structure representing the securityfs node.
* @data: Supplies a buffer passed to the write syscall.
* @len: Supplies the length of @data.
* @offset: unused.
*
* Return:
* * Length of buffer written - Success
* * %-EPERM - Insufficient permission
* * %-EINVAL - Invalid input
* * %-ENOENT - Policy initializing/deleted
*/
static ssize_t setactive(struct file *f, const char __user *data,
size_t len, loff_t *offset)
{
const struct ipe_policy *p = NULL;
struct inode *root = NULL;
bool value = false;
int rc = 0;
if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
return -EPERM;
rc = kstrtobool_from_user(data, len, &value);
if (rc)
return rc;
if (!value)
return -EINVAL;
root = d_inode(f->f_path.dentry->d_parent);
inode_lock(root);
p = (struct ipe_policy *)root->i_private;
if (!p) {
rc = -ENOENT;
goto out;
}
rc = ipe_set_active_pol(p);
out:
inode_unlock(root);
return (rc < 0) ? rc : len;
}
/**
* getactive() - Read handler for "ipe/policies/$name/active".
* @f: Supplies a file structure representing the securityfs node.
* @data: Supplies a buffer passed to the write syscall.
* @len: Supplies the length of @data.
* @offset: unused.
*
* @data will be populated with the 1 or 0 depending on if the
* corresponding policy is active.
*
* Return:
* * Length of buffer written - Success
* * %-ENOENT - Policy initializing/deleted
*/
static ssize_t getactive(struct file *f, char __user *data,
size_t len, loff_t *offset)
{
const struct ipe_policy *p = NULL;
struct inode *root = NULL;
const char *str;
int rc = 0;
root = d_inode(f->f_path.dentry->d_parent);
inode_lock_shared(root);
p = (struct ipe_policy *)root->i_private;
if (!p) {
inode_unlock_shared(root);
return -ENOENT;
}
inode_unlock_shared(root);
str = (p == rcu_access_pointer(ipe_active_policy)) ? "1" : "0";
rc = simple_read_from_buffer(data, len, offset, str, 1);
return rc;
}
/**
* update_policy() - Write handler for "ipe/policies/$name/update".
* @f: Supplies a file structure representing the securityfs node.
* @data: Supplies a buffer passed to the write syscall.
* @len: Supplies the length of @data.
* @offset: unused.
*
* On success this updates the policy represented by $name,
* in-place.
*
* Return: Length of buffer written on success. If an error occurs,
* the function will return the -errno.
*/
static ssize_t update_policy(struct file *f, const char __user *data,
size_t len, loff_t *offset)
{
struct inode *root = NULL;
char *copy = NULL;
int rc = 0;
if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
return -EPERM;
copy = memdup_user(data, len);
if (IS_ERR(copy))
return PTR_ERR(copy);
root = d_inode(f->f_path.dentry->d_parent);
inode_lock(root);
rc = ipe_update_policy(root, NULL, 0, copy, len);
inode_unlock(root);
kfree(copy);
if (rc)
return rc;
return len;
}
/**
* delete_policy() - write handler for "ipe/policies/$name/delete".
* @f: Supplies a file structure representing the securityfs node.
* @data: Supplies a buffer passed to the write syscall.
* @len: Supplies the length of @data.
* @offset: unused.
*
* On success this deletes the policy represented by $name.
*
* Return:
* * Length of buffer written - Success
* * %-EPERM - Insufficient permission/deleting active policy
* * %-EINVAL - Invalid input
* * %-ENOENT - Policy initializing/deleted
*/
static ssize_t delete_policy(struct file *f, const char __user *data,
size_t len, loff_t *offset)
{
struct ipe_policy *ap = NULL;
struct ipe_policy *p = NULL;
struct inode *root = NULL;
bool value = false;
int rc = 0;
if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
return -EPERM;
rc = kstrtobool_from_user(data, len, &value);
if (rc)
return rc;
if (!value)
return -EINVAL;
root = d_inode(f->f_path.dentry->d_parent);
inode_lock(root);
p = (struct ipe_policy *)root->i_private;
if (!p) {
inode_unlock(root);
return -ENOENT;
}
mutex_lock(&ipe_policy_lock);
ap = rcu_dereference_protected(ipe_active_policy,
lockdep_is_held(&ipe_policy_lock));
if (p == ap) {
mutex_unlock(&ipe_policy_lock);
inode_unlock(root);
return -EPERM;
}
mutex_unlock(&ipe_policy_lock);
root->i_private = NULL;
inode_unlock(root);
synchronize_rcu();
ipe_free_policy(p);
return len;
}
static const struct file_operations content_fops = {
.read = read_policy,
};
static const struct file_operations pkcs7_fops = {
.read = read_pkcs7,
};
static const struct file_operations name_fops = {
.read = read_name,
};
static const struct file_operations ver_fops = {
.read = read_version,
};
static const struct file_operations active_fops = {
.write = setactive,
.read = getactive,
};
static const struct file_operations update_fops = {
.write = update_policy,
};
static const struct file_operations delete_fops = {
.write = delete_policy,
};
/**
* policy_subdir - files under a policy subdirectory
*/
static const struct ipefs_file policy_subdir[] = {
{ "pkcs7", 0444, &pkcs7_fops },
{ "policy", 0444, &content_fops },
{ "name", 0444, &name_fops },
{ "version", 0444, &ver_fops },
{ "active", 0600, &active_fops },
{ "update", 0200, &update_fops },
{ "delete", 0200, &delete_fops },
};
/**
* ipe_del_policyfs_node() - Delete a securityfs entry for @p.
* @p: Supplies a pointer to the policy to delete a securityfs entry for.
*/
void ipe_del_policyfs_node(struct ipe_policy *p)
{
securityfs_recursive_remove(p->policyfs);
p->policyfs = NULL;
}
/**
* ipe_new_policyfs_node() - Create a securityfs entry for @p.
* @p: Supplies a pointer to the policy to create a securityfs entry for.
*
* Return: %0 on success. If an error occurs, the function will return
* the -errno.
*/
int ipe_new_policyfs_node(struct ipe_policy *p)
{
const struct ipefs_file *f = NULL;
struct dentry *policyfs = NULL;
struct inode *root = NULL;
struct dentry *d = NULL;
size_t i = 0;
int rc = 0;
if (p->policyfs)
return 0;
policyfs = securityfs_create_dir(p->parsed->name, policy_root);
if (IS_ERR(policyfs))
return PTR_ERR(policyfs);
root = d_inode(policyfs);
for (i = 0; i < ARRAY_SIZE(policy_subdir); ++i) {
f = &policy_subdir[i];
d = securityfs_create_file(f->name, f->access, policyfs,
NULL, f->fops);
if (IS_ERR(d)) {
rc = PTR_ERR(d);
goto err;
}
}
inode_lock(root);
p->policyfs = policyfs;
root->i_private = p;
inode_unlock(root);
return 0;
err:
securityfs_recursive_remove(policyfs);
return rc;
}
Codebase Browser
linux