// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
*/
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/sched.h>
#include <linux/rcupdate.h>
#include <linux/moduleparam.h>
#include <linux/fsverity.h>
#include "ipe.h"
#include "eval.h"
#include "policy.h"
#include "audit.h"
#include "digest.h"
struct ipe_policy __rcu *ipe_active_policy;
bool success_audit;
bool enforce = true;
#define INO_BLOCK_DEV(ino) ((ino)->i_sb->s_bdev)
#define FILE_SUPERBLOCK(f) ((f)->f_path.mnt->mnt_sb)
/**
* build_ipe_sb_ctx() - Build initramfs field of an ipe evaluation context.
* @ctx: Supplies a pointer to the context to be populated.
* @file: Supplies the file struct of the file triggered IPE event.
*/
static void build_ipe_sb_ctx(struct ipe_eval_ctx *ctx, const struct file *const file)
{
ctx->initramfs = ipe_sb(FILE_SUPERBLOCK(file))->initramfs;
}
#ifdef CONFIG_IPE_PROP_DM_VERITY
/**
* build_ipe_bdev_ctx() - Build ipe_bdev field of an evaluation context.
* @ctx: Supplies a pointer to the context to be populated.
* @ino: Supplies the inode struct of the file triggered IPE event.
*/
static void build_ipe_bdev_ctx(struct ipe_eval_ctx *ctx, const struct inode *const ino)
{
if (INO_BLOCK_DEV(ino))
ctx->ipe_bdev = ipe_bdev(INO_BLOCK_DEV(ino));
}
#else
static void build_ipe_bdev_ctx(struct ipe_eval_ctx *ctx, const struct inode *const ino)
{
}
#endif /* CONFIG_IPE_PROP_DM_VERITY */
#ifdef CONFIG_IPE_PROP_FS_VERITY
#ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG
static void build_ipe_inode_blob_ctx(struct ipe_eval_ctx *ctx,
const struct inode *const ino)
{
ctx->ipe_inode = ipe_inode(ctx->ino);
}
#else
static inline void build_ipe_inode_blob_ctx(struct ipe_eval_ctx *ctx,
const struct inode *const ino)
{
}
#endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
/**
* build_ipe_inode_ctx() - Build inode fields of an evaluation context.
* @ctx: Supplies a pointer to the context to be populated.
* @ino: Supplies the inode struct of the file triggered IPE event.
*/
static void build_ipe_inode_ctx(struct ipe_eval_ctx *ctx, const struct inode *const ino)
{
ctx->ino = ino;
build_ipe_inode_blob_ctx(ctx, ino);
}
#else
static void build_ipe_inode_ctx(struct ipe_eval_ctx *ctx, const struct inode *const ino)
{
}
#endif /* CONFIG_IPE_PROP_FS_VERITY */
/**
* ipe_build_eval_ctx() - Build an ipe evaluation context.
* @ctx: Supplies a pointer to the context to be populated.
* @file: Supplies a pointer to the file to associated with the evaluation.
* @op: Supplies the IPE policy operation associated with the evaluation.
* @hook: Supplies the LSM hook associated with the evaluation.
*/
void ipe_build_eval_ctx(struct ipe_eval_ctx *ctx,
const struct file *file,
enum ipe_op_type op,
enum ipe_hook_type hook)
{
struct inode *ino;
ctx->file = file;
ctx->op = op;
ctx->hook = hook;
if (file) {
build_ipe_sb_ctx(ctx, file);
ino = d_real_inode(file->f_path.dentry);
build_ipe_bdev_ctx(ctx, ino);
build_ipe_inode_ctx(ctx, ino);
}
}
/**
* evaluate_boot_verified() - Evaluate @ctx for the boot verified property.
* @ctx: Supplies a pointer to the context being evaluated.
*
* Return:
* * %true - The current @ctx match the @p
* * %false - The current @ctx doesn't match the @p
*/
static bool evaluate_boot_verified(const struct ipe_eval_ctx *const ctx)
{
return ctx->initramfs;
}
#ifdef CONFIG_IPE_PROP_DM_VERITY
/**
* evaluate_dmv_roothash() - Evaluate @ctx against a dmv roothash property.
* @ctx: Supplies a pointer to the context being evaluated.
* @p: Supplies a pointer to the property being evaluated.
*
* Return:
* * %true - The current @ctx match the @p
* * %false - The current @ctx doesn't match the @p
*/
static bool evaluate_dmv_roothash(const struct ipe_eval_ctx *const ctx,
struct ipe_prop *p)
{
return !!ctx->ipe_bdev &&
!!ctx->ipe_bdev->root_hash &&
ipe_digest_eval(p->value,
ctx->ipe_bdev->root_hash);
}
#else
static bool evaluate_dmv_roothash(const struct ipe_eval_ctx *const ctx,
struct ipe_prop *p)
{
return false;
}
#endif /* CONFIG_IPE_PROP_DM_VERITY */
#ifdef CONFIG_IPE_PROP_DM_VERITY_SIGNATURE
/**
* evaluate_dmv_sig_false() - Evaluate @ctx against a dmv sig false property.
* @ctx: Supplies a pointer to the context being evaluated.
*
* Return:
* * %true - The current @ctx match the property
* * %false - The current @ctx doesn't match the property
*/
static bool evaluate_dmv_sig_false(const struct ipe_eval_ctx *const ctx)
{
return !ctx->ipe_bdev || (!ctx->ipe_bdev->dm_verity_signed);
}
/**
* evaluate_dmv_sig_true() - Evaluate @ctx against a dmv sig true property.
* @ctx: Supplies a pointer to the context being evaluated.
*
* Return:
* * %true - The current @ctx match the property
* * %false - The current @ctx doesn't match the property
*/
static bool evaluate_dmv_sig_true(const struct ipe_eval_ctx *const ctx)
{
return !evaluate_dmv_sig_false(ctx);
}
#else
static bool evaluate_dmv_sig_false(const struct ipe_eval_ctx *const ctx)
{
return false;
}
static bool evaluate_dmv_sig_true(const struct ipe_eval_ctx *const ctx)
{
return false;
}
#endif /* CONFIG_IPE_PROP_DM_VERITY_SIGNATURE */
#ifdef CONFIG_IPE_PROP_FS_VERITY
/**
* evaluate_fsv_digest() - Evaluate @ctx against a fsv digest property.
* @ctx: Supplies a pointer to the context being evaluated.
* @p: Supplies a pointer to the property being evaluated.
*
* Return:
* * %true - The current @ctx match the @p
* * %false - The current @ctx doesn't match the @p
*/
static bool evaluate_fsv_digest(const struct ipe_eval_ctx *const ctx,
struct ipe_prop *p)
{
enum hash_algo alg;
u8 digest[FS_VERITY_MAX_DIGEST_SIZE];
struct digest_info info;
if (!ctx->ino)
return false;
if (!fsverity_get_digest((struct inode *)ctx->ino,
digest,
NULL,
&alg))
return false;
info.alg = hash_algo_name[alg];
info.digest = digest;
info.digest_len = hash_digest_size[alg];
return ipe_digest_eval(p->value, &info);
}
#else
static bool evaluate_fsv_digest(const struct ipe_eval_ctx *const ctx,
struct ipe_prop *p)
{
return false;
}
#endif /* CONFIG_IPE_PROP_FS_VERITY */
#ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG
/**
* evaluate_fsv_sig_false() - Evaluate @ctx against a fsv sig false property.
* @ctx: Supplies a pointer to the context being evaluated.
*
* Return:
* * %true - The current @ctx match the property
* * %false - The current @ctx doesn't match the property
*/
static bool evaluate_fsv_sig_false(const struct ipe_eval_ctx *const ctx)
{
return !ctx->ino ||
!IS_VERITY(ctx->ino) ||
!ctx->ipe_inode ||
!ctx->ipe_inode->fs_verity_signed;
}
/**
* evaluate_fsv_sig_true() - Evaluate @ctx against a fsv sig true property.
* @ctx: Supplies a pointer to the context being evaluated.
*
* Return:
* * %true - The current @ctx match the property
* * %false - The current @ctx doesn't match the property
*/
static bool evaluate_fsv_sig_true(const struct ipe_eval_ctx *const ctx)
{
return !evaluate_fsv_sig_false(ctx);
}
#else
static bool evaluate_fsv_sig_false(const struct ipe_eval_ctx *const ctx)
{
return false;
}
static bool evaluate_fsv_sig_true(const struct ipe_eval_ctx *const ctx)
{
return false;
}
#endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
/**
* evaluate_property() - Analyze @ctx against a rule property.
* @ctx: Supplies a pointer to the context to be evaluated.
* @p: Supplies a pointer to the property to be evaluated.
*
* This function Determines whether the specified @ctx
* matches the conditions defined by a rule property @p.
*
* Return:
* * %true - The current @ctx match the @p
* * %false - The current @ctx doesn't match the @p
*/
static bool evaluate_property(const struct ipe_eval_ctx *const ctx,
struct ipe_prop *p)
{
switch (p->type) {
case IPE_PROP_BOOT_VERIFIED_FALSE:
return !evaluate_boot_verified(ctx);
case IPE_PROP_BOOT_VERIFIED_TRUE:
return evaluate_boot_verified(ctx);
case IPE_PROP_DMV_ROOTHASH:
return evaluate_dmv_roothash(ctx, p);
case IPE_PROP_DMV_SIG_FALSE:
return evaluate_dmv_sig_false(ctx);
case IPE_PROP_DMV_SIG_TRUE:
return evaluate_dmv_sig_true(ctx);
case IPE_PROP_FSV_DIGEST:
return evaluate_fsv_digest(ctx, p);
case IPE_PROP_FSV_SIG_FALSE:
return evaluate_fsv_sig_false(ctx);
case IPE_PROP_FSV_SIG_TRUE:
return evaluate_fsv_sig_true(ctx);
default:
return false;
}
}
/**
* ipe_evaluate_event() - Analyze @ctx against the current active policy.
* @ctx: Supplies a pointer to the context to be evaluated.
*
* This is the loop where all policy evaluations happen against the IPE policy.
*
* Return:
* * %0 - Success
* * %-EACCES - @ctx did not pass evaluation
*/
int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx)
{
const struct ipe_op_table *rules = NULL;
const struct ipe_rule *rule = NULL;
struct ipe_policy *pol = NULL;
struct ipe_prop *prop = NULL;
enum ipe_action_type action;
enum ipe_match match_type;
bool match = false;
int rc = 0;
rcu_read_lock();
pol = rcu_dereference(ipe_active_policy);
if (!pol) {
rcu_read_unlock();
return 0;
}
if (ctx->op == IPE_OP_INVALID) {
if (pol->parsed->global_default_action == IPE_ACTION_INVALID) {
WARN(1, "no default rule set for unknown op, ALLOW it");
action = IPE_ACTION_ALLOW;
} else {
action = pol->parsed->global_default_action;
}
match_type = IPE_MATCH_GLOBAL;
goto eval;
}
rules = &pol->parsed->rules[ctx->op];
list_for_each_entry(rule, &rules->rules, next) {
match = true;
list_for_each_entry(prop, &rule->props, next) {
match = evaluate_property(ctx, prop);
if (!match)
break;
}
if (match)
break;
}
if (match) {
action = rule->action;
match_type = IPE_MATCH_RULE;
} else if (rules->default_action != IPE_ACTION_INVALID) {
action = rules->default_action;
match_type = IPE_MATCH_TABLE;
} else {
action = pol->parsed->global_default_action;
match_type = IPE_MATCH_GLOBAL;
}
eval:
ipe_audit_match(ctx, match_type, action, rule);
rcu_read_unlock();
if (action == IPE_ACTION_DENY)
rc = -EACCES;
if (!READ_ONCE(enforce))
rc = 0;
return rc;
}
/* Set the right module name */
#ifdef KBUILD_MODNAME
#undef KBUILD_MODNAME
#define KBUILD_MODNAME "ipe"
#endif
module_param(success_audit, bool, 0400);
MODULE_PARM_DESC(success_audit, "Start IPE with success auditing enabled");
module_param(enforce, bool, 0400);
MODULE_PARM_DESC(enforce, "Start IPE in enforce or permissive mode");
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