1 files changed, 393 insertions, 0 deletions
diff --git a/security/ipe/eval.c b/security/ipe/eval.c
new file mode 100644
index 000000000000..21439c5be336
--- /dev/null
+++ b/security/ipe/eval.c
@@ -0,0 +1,393 @@
+// 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");