diff mbox series

[RFC,v8,02/17] ipe: add policy parser

Message ID 1654714889-26728-3-git-send-email-deven.desai@linux.microsoft.com (mailing list archive)
State New, archived
Headers show
Series Integrity Policy Enforcement LSM (IPE) | expand

Commit Message

Deven Bowers June 8, 2022, 7:01 p.m. UTC
IPE's interpretation of the what the user trusts is accomplished through
its policy. IPE's design is to not provide support for a single trust
provider, but to support multiple providers to enable the end-user to
choose the best one to seek their needs.

This requires the policy to be rather flexible and modular so that
integrity providers, like fs-verity, dm-verity, dm-integrity, or
some other system, can plug into the policy with minimal code changes,
and IPE can

Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com>

---
v2:
  + Split evaluation loop, access control hooks,
    and evaluation loop from policy parser and userspace
    interface to pass mailing list character limit

v3:
  + Move policy load and activation audit event to 03/12
  + Fix a potential panic when a policy failed to load.
  + use pr_warn for a failure to parse instead of an
    audit record
  + Remove comments from headers
  + Add lockdep assertions to ipe_update_active_policy and
    ipe_activate_policy
  + Fix up warnings with checkpatch --strict
  + Use file_ns_capable for CAP_MAC_ADMIN for securityfs
    nodes.
  + Use memdup_user instead of kzalloc+simple_write_to_buffer.
  + Remove strict_parse command line parameter, as it is added
    by the sysctl command line.
  + Prefix extern variables with ipe_

v4:
  + Remove securityfs to reverse-dependency
  + Add SHA1 reverse dependency.
  + Add versioning scheme for IPE properties, and associated
    interface to query the versioning scheme.
  + Cause a parser to always return an error on unknown syntax.
  + Remove strict_parse option
  + Change active_policy interface from sysctl, to securityfs,
    and change scheme.

v5:
  + Cause an error if a default action is not defined for each
    operaiton.
  + Minor function renames

v6:
  + No changes

v7:
  + Further split parser and userspace interface into two
    separate commits, for easier review.

  + Refactor policy parser to make code cleaner via introducing a
    more modular design, for easier extension of policy, and
    easier review.

v8:
  + remove unnecessary pr_info emission on parser loading

  + add explicit newline to the pr_err emitted when a parser
    fails to load.
---
 include/asm-generic/vmlinux.lds.h    |  16 +
 security/ipe/Makefile                |   6 +
 security/ipe/ipe.c                   |  61 ++
 security/ipe/ipe.h                   |   5 +
 security/ipe/ipe_parser.h            |  59 ++
 security/ipe/modules.c               | 109 +++
 security/ipe/modules.h               |  17 +
 security/ipe/modules/ipe_module.h    |  33 +
 security/ipe/parsers.c               | 143 ++++
 security/ipe/parsers/Makefile        |  12 +
 security/ipe/parsers/default.c       | 106 +++
 security/ipe/parsers/policy_header.c | 126 ++++
 security/ipe/policy.c                | 946 +++++++++++++++++++++++++++
 security/ipe/policy.h                |  97 +++
 14 files changed, 1736 insertions(+)
 create mode 100644 security/ipe/ipe_parser.h
 create mode 100644 security/ipe/modules.c
 create mode 100644 security/ipe/modules.h
 create mode 100644 security/ipe/modules/ipe_module.h
 create mode 100644 security/ipe/parsers.c
 create mode 100644 security/ipe/parsers/Makefile
 create mode 100644 security/ipe/parsers/default.c
 create mode 100644 security/ipe/parsers/policy_header.c
 create mode 100644 security/ipe/policy.c
 create mode 100644 security/ipe/policy.h

Comments

Paul Moore June 15, 2022, 10:12 p.m. UTC | #1
On Wed, Jun 8, 2022 at 3:03 PM Deven Bowers
<deven.desai@linux.microsoft.com> wrote:
>
> IPE's interpretation of the what the user trusts is accomplished through
> its policy. IPE's design is to not provide support for a single trust
> provider, but to support multiple providers to enable the end-user to
> choose the best one to seek their needs.
>
> This requires the policy to be rather flexible and modular so that
> integrity providers, like fs-verity, dm-verity, dm-integrity, or
> some other system, can plug into the policy with minimal code changes,
> and IPE can
>
> Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com>
>
> ---
> v2:
>   + Split evaluation loop, access control hooks,
>     and evaluation loop from policy parser and userspace
>     interface to pass mailing list character limit
>
> v3:
>   + Move policy load and activation audit event to 03/12
>   + Fix a potential panic when a policy failed to load.
>   + use pr_warn for a failure to parse instead of an
>     audit record
>   + Remove comments from headers
>   + Add lockdep assertions to ipe_update_active_policy and
>     ipe_activate_policy
>   + Fix up warnings with checkpatch --strict
>   + Use file_ns_capable for CAP_MAC_ADMIN for securityfs
>     nodes.
>   + Use memdup_user instead of kzalloc+simple_write_to_buffer.
>   + Remove strict_parse command line parameter, as it is added
>     by the sysctl command line.
>   + Prefix extern variables with ipe_
>
> v4:
>   + Remove securityfs to reverse-dependency
>   + Add SHA1 reverse dependency.
>   + Add versioning scheme for IPE properties, and associated
>     interface to query the versioning scheme.
>   + Cause a parser to always return an error on unknown syntax.
>   + Remove strict_parse option
>   + Change active_policy interface from sysctl, to securityfs,
>     and change scheme.
>
> v5:
>   + Cause an error if a default action is not defined for each
>     operaiton.
>   + Minor function renames
>
> v6:
>   + No changes
>
> v7:
>   + Further split parser and userspace interface into two
>     separate commits, for easier review.
>
>   + Refactor policy parser to make code cleaner via introducing a
>     more modular design, for easier extension of policy, and
>     easier review.
>
> v8:
>   + remove unnecessary pr_info emission on parser loading
>
>   + add explicit newline to the pr_err emitted when a parser
>     fails to load.
> ---
>  include/asm-generic/vmlinux.lds.h    |  16 +
>  security/ipe/Makefile                |   6 +
>  security/ipe/ipe.c                   |  61 ++
>  security/ipe/ipe.h                   |   5 +
>  security/ipe/ipe_parser.h            |  59 ++
>  security/ipe/modules.c               | 109 +++
>  security/ipe/modules.h               |  17 +
>  security/ipe/modules/ipe_module.h    |  33 +
>  security/ipe/parsers.c               | 143 ++++
>  security/ipe/parsers/Makefile        |  12 +
>  security/ipe/parsers/default.c       | 106 +++
>  security/ipe/parsers/policy_header.c | 126 ++++
>  security/ipe/policy.c                | 946 +++++++++++++++++++++++++++
>  security/ipe/policy.h                |  97 +++
>  14 files changed, 1736 insertions(+)
>  create mode 100644 security/ipe/ipe_parser.h
>  create mode 100644 security/ipe/modules.c
>  create mode 100644 security/ipe/modules.h
>  create mode 100644 security/ipe/modules/ipe_module.h
>  create mode 100644 security/ipe/parsers.c
>  create mode 100644 security/ipe/parsers/Makefile
>  create mode 100644 security/ipe/parsers/default.c
>  create mode 100644 security/ipe/parsers/policy_header.c
>  create mode 100644 security/ipe/policy.c
>  create mode 100644 security/ipe/policy.h

I had a few small comments while reading through this code, e.g. try
to drop the support for quoted values, but I think my big issue here
is that non-trivial string parsers in the kernel make me nervous and
with +1700 lines spread across 14 files this is definitely a
non-trivial parser.

I understand the basic 'key=value' pair format, and I think that's
okay, but I worry about the added complexity in the parser brought
about by the need to introduce an abstraction layer between the core
parser(s) and modules.  I realize flexibility is an important part of
IPE, and this relies on the ability to add support for new language
keys/modules, but I don't believe that requires the level of
indirection seen here.

I'm not asking you to make radical changes to the IPE policy language,
but I do believe spending some time to rethink how you parse the
language would be a good idea.  When in doubt keep the parser as
simple as possible, you can always add complexity and more nuance in
the future when the language requires it.  The IPE policy language
grammar is the immutable kernel/userspace API promise, not the parser
implementation.

--
paul-moore.com
diff mbox series

Patch

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 7515a465ec03..8549b98d0cf6 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -284,6 +284,20 @@ 
 #define EARLY_LSM_TABLE()
 #endif
 
+#ifdef CONFIG_SECURITY_IPE
+#define IPE_PARSER_TABLE()	. = ALIGN(8);				\
+				__start_ipe_parsers = .;		\
+				KEEP(*(.ipe_parsers))		\
+				__end_ipe_parsers = .;
+#define IPE_MODULE_TABLE()	. = ALIGN(8);				\
+				__start_ipe_modules = .;		\
+				KEEP(*(.ipe_modules))			\
+				__end_ipe_modules = .;
+#else
+#define IPE_PARSER_TABLE()
+#define IPE_MODULE_TABLE()
+#endif
+
 #define ___OF_TABLE(cfg, name)	_OF_TABLE_##cfg(name)
 #define __OF_TABLE(cfg, name)	___OF_TABLE(cfg, name)
 #define OF_TABLE(cfg, name)	__OF_TABLE(IS_ENABLED(cfg), name)
@@ -436,6 +450,8 @@ 
 		KEEP(*(__tracepoints_ptrs)) /* Tracepoints: pointer array */ \
 		__stop___tracepoints_ptrs = .;				\
 		*(__tracepoints_strings)/* Tracepoints: strings */	\
+		IPE_PARSER_TABLE()					\
+		IPE_MODULE_TABLE()					\
 	}								\
 									\
 	.rodata1          : AT(ADDR(.rodata1) - LOAD_OFFSET) {		\
diff --git a/security/ipe/Makefile b/security/ipe/Makefile
index ba3df729e252..9a97efd8a190 100644
--- a/security/ipe/Makefile
+++ b/security/ipe/Makefile
@@ -5,7 +5,13 @@ 
 # Makefile for building the IPE module as part of the kernel tree.
 #
 
+ccflags-y := -I$(srctree)/security/ipe/modules
+
 obj-$(CONFIG_SECURITY_IPE) += \
 	ctx.o \
 	hooks.o \
 	ipe.o \
+	modules.o \
+	parsers/ \
+	parsers.o \
+	policy.o \
diff --git a/security/ipe/ipe.c b/security/ipe/ipe.c
index 8a1e0b1c7240..3f387f4ab38a 100644
--- a/security/ipe/ipe.c
+++ b/security/ipe/ipe.c
@@ -6,6 +6,9 @@ 
 #include "ipe.h"
 #include "ctx.h"
 #include "hooks.h"
+#include "ipe_parser.h"
+#include "modules/ipe_module.h"
+#include "modules.h"
 
 #include <linux/fs.h>
 #include <linux/sched.h>
@@ -40,6 +43,56 @@  struct ipe_context __rcu **ipe_tsk_ctx(struct task_struct *tsk)
 	return tsk->security + ipe_blobs.lbs_task;
 }
 
+/*
+ * load_parsers: Load all the parsers compiled into IPE. This needs
+ *		 to be called prior to the boot policy being loaded.
+ *
+ * Return:
+ * 0 - OK
+ * !0 - Error
+ */
+static int load_parsers(void)
+{
+	int rc = 0;
+	struct ipe_parser *parser;
+
+	for (parser = __start_ipe_parsers; parser < __end_ipe_parsers; ++parser) {
+		rc = ipe_register_parser(parser);
+		if (rc) {
+			pr_err("failed to initialize '%s'", parser->first_token);
+			return rc;
+		}
+
+		pr_info("initialized parser module '%s'", parser->first_token);
+	}
+
+	return 0;
+}
+
+/**
+ * load_modules: Load all the modules compiled into IPE. This needs
+ *		 to be called prior to the boot policy being loaded.
+ *
+ * Return:
+ * 0 - OK
+ * !0 - Error
+ */
+static int load_modules(void)
+{
+	int rc = 0;
+	struct ipe_module *m;
+
+	for (m = __start_ipe_modules; m < __end_ipe_modules; ++m) {
+		rc = ipe_register_module(m);
+		if (rc) {
+			pr_err("failed to initialize '%s'\n", m->name);
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
 /**
  * ipe_init: Entry point of IPE.
  *
@@ -57,6 +110,14 @@  static int __init ipe_init(void)
 {
 	int rc = 0;
 
+	rc = load_parsers();
+	if (rc)
+		return rc;
+
+	rc = load_modules();
+	if (rc)
+		return rc;
+
 	rc = ipe_init_ctx();
 	if (rc)
 		return rc;
diff --git a/security/ipe/ipe.h b/security/ipe/ipe.h
index 152ae28f3cdd..417b474e0543 100644
--- a/security/ipe/ipe.h
+++ b/security/ipe/ipe.h
@@ -9,9 +9,14 @@ 
 #define pr_fmt(fmt) "IPE " fmt "\n"
 
 #include "ctx.h"
+#include "ipe_parser.h"
+#include "modules/ipe_module.h"
 
 #include <linux/types.h>
 #include <linux/sched.h>
 #include <linux/lsm_hooks.h>
 
+extern struct ipe_parser __start_ipe_parsers[], __end_ipe_parsers[];
+extern struct ipe_module __start_ipe_modules[], __end_ipe_modules[];
+
 #endif /* IPE_H */
diff --git a/security/ipe/ipe_parser.h b/security/ipe/ipe_parser.h
new file mode 100644
index 000000000000..f7c5c11bde44
--- /dev/null
+++ b/security/ipe/ipe_parser.h
@@ -0,0 +1,59 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+#ifndef IPE_PARSER_H
+#define IPE_PARSER_H
+
+#include "policy.h"
+
+#include <linux/list.h>
+#include <linux/types.h>
+
+/*
+ * Struct used to define internal parsers that effect the policy,
+ * but do not belong as policy modules, as they are not used to make
+ * decisions in the event loop, and only effect the internal workings
+ * of IPE.
+ *
+ * These structures are used in pass2, and policy deallocation.
+ */
+struct ipe_parser {
+	u8 version;
+	const char *first_token;
+
+	int (*parse)(const struct ipe_policy_line *line,
+		     struct ipe_parsed_policy *pol);
+	int (*free)(struct ipe_parsed_policy *pol);
+	int (*validate)(const struct ipe_parsed_policy *pol);
+};
+
+int ipe_parse_op(const struct ipe_policy_token *tok,
+		 enum ipe_operation *op);
+
+int ipe_parse_action(const struct ipe_policy_token *tok,
+		     enum ipe_action *action);
+
+/*
+ * Optional struct to make structured parsers easier.
+ */
+struct ipe_token_parser {
+	const char *key;
+	int (*parse_token)(const struct ipe_policy_token *t,
+			   struct ipe_parsed_policy *p);
+};
+
+const struct ipe_parser *ipe_lookup_parser(const char *first_token);
+
+int ipe_for_each_parser(int (*view)(const struct ipe_parser *parser,
+				    void *ctx),
+			void *ctx);
+
+int ipe_register_parser(struct ipe_parser *p);
+
+#define IPE_PARSER(parser)				\
+	static struct ipe_parser __ipe_parser_##parser	\
+		__used __section(".ipe_parsers")	\
+		__aligned(sizeof(unsigned long))
+
+#endif /* IPE_PARSER_MODULE_H */
diff --git a/security/ipe/modules.c b/security/ipe/modules.c
new file mode 100644
index 000000000000..fb100c14cce5
--- /dev/null
+++ b/security/ipe/modules.c
@@ -0,0 +1,109 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+
+#include "ipe.h"
+#include "modules.h"
+
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/rbtree.h>
+
+static struct rb_root module_root = RB_ROOT;
+
+struct module_container {
+	struct rb_node node;
+	const struct ipe_module *mod;
+};
+
+/**
+ * cmp_node: Comparator for a node in the module lookup tree.
+ * @n: First node to compare
+ * @nn: Second node to compare
+ *
+ * Return:
+ * <0 - @n's key is lexigraphically before @nn.
+ * 0 - n's key is identical to @nn
+ * >0 - n's key is legxigraphically after @nn
+ */
+static int cmp_node(struct rb_node *n, const struct rb_node *nn)
+{
+	const struct module_container *c1;
+	const struct module_container *c2;
+
+	c1 = container_of(n, struct module_container, node);
+	c2 = container_of(nn, struct module_container, node);
+
+	return strcmp(c1->mod->name, c2->mod->name);
+}
+
+/**
+ * cmp_key: Comparator to find a module in the tree by key.
+ * @key: Supplies a pointer to a null-terminated string key
+ * @n: Node to compare @key against
+ *
+ * Return:
+ * <0 - Desired node is to the left of @n
+ * 0  - @n is the desired node
+ * >0 - Desired node is to the right of @n
+ */
+static int cmp_key(const void *key, const struct rb_node *n)
+{
+	struct module_container *mod;
+
+	mod = container_of(n, struct module_container, node);
+
+	return strcmp((const char *)key, mod->mod->name);
+}
+
+/**
+ * ipe_lookup_module: Attempt to find a ipe_pmodule structure by @key.
+ * @key: The key to look for in the tree.
+ *
+ * Return:
+ * !NULL - OK
+ * NULL - No property exists under @key
+ */
+const struct ipe_module *ipe_lookup_module(const char *key)
+{
+	struct rb_node *n;
+
+	n = rb_find(key, &module_root, cmp_key);
+	if (!n)
+		return NULL;
+
+	return container_of(n, struct module_container, node)->mod;
+}
+
+/**
+ * ipe_register_module: Register a policy module to be used in IPE's policy.
+ * @m: Module to register.
+ *
+ * This function allows parsers (policy constructs that represent integrations
+ * with other subsystems, to be leveraged in rules) to be leveraged in IPE policy.
+ * This must be called prior to any policies being loaded.
+ *
+ * Return:
+ * 0 - OK
+ * !0 - Error
+ */
+int ipe_register_module(struct ipe_module *m)
+{
+	struct rb_node *n = NULL;
+	struct module_container *c = NULL;
+
+	c = kzalloc(sizeof(*c), GFP_KERNEL);
+	if (!c)
+		return -ENOMEM;
+
+	c->mod = m;
+
+	n = rb_find_add(&c->node, &module_root, cmp_node);
+	if (n) {
+		kfree(c);
+		return -EEXIST;
+	}
+
+	return 0;
+}
diff --git a/security/ipe/modules.h b/security/ipe/modules.h
new file mode 100644
index 000000000000..7b897bdd870b
--- /dev/null
+++ b/security/ipe/modules.h
@@ -0,0 +1,17 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+#ifndef IPE_MODULES_H
+#define IPE_MODULES_H
+
+#include "ipe.h"
+#include "ipe_module.h"
+
+#include <linux/types.h>
+#include <linux/rbtree.h>
+
+const struct ipe_module *ipe_lookup_module(const char *key);
+int ipe_register_module(struct ipe_module *m);
+
+#endif /* IPE_MODULES_H */
diff --git a/security/ipe/modules/ipe_module.h b/security/ipe/modules/ipe_module.h
new file mode 100644
index 000000000000..c4e98b548df3
--- /dev/null
+++ b/security/ipe/modules/ipe_module.h
@@ -0,0 +1,33 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+#ifndef IPE_MODULE_H
+#define IPE_MODULE_H
+
+#include <linux/types.h>
+
+/**
+ * ipe_module: definition of an extensible module for IPE properties.
+ *	       These structures are used to implement 'key=value' pairs
+ *	       in IPE policy, which will be evaluated on every IPE policy
+ *	       evaluation.
+ *
+ *	       Integrity mechanisms should be define as a module, and modules
+ *	       should manage their own dependencies via KConfig. @name is both
+ *	       the key half of the key=value pair in the policy, and the unique
+ *	       identifier for the module.
+ */
+struct ipe_module {
+	const char			*const name;	/* required */
+	u16				version;	/* required */
+	int (*parse)(const char *valstr, void **value);	/* required */
+	void (*free)(void **value);			/* optional */
+};
+
+#define IPE_MODULE(parser)				\
+	static struct ipe_module __ipe_module_##parser	\
+		__used __section(".ipe_modules")	\
+		__aligned(sizeof(unsigned long))
+
+#endif /* IPE_MODULE_H */
diff --git a/security/ipe/parsers.c b/security/ipe/parsers.c
new file mode 100644
index 000000000000..87006270b9cd
--- /dev/null
+++ b/security/ipe/parsers.c
@@ -0,0 +1,143 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+
+#include "policy.h"
+#include "ipe_parser.h"
+
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/rbtree.h>
+
+/*
+ * locking unnecessary, this is called by lsm_init,
+ * and is read-only after that point.
+ */
+static struct rb_root ipe_parser_root = RB_ROOT;
+
+struct parser_container {
+	struct rb_node node;
+	const struct ipe_parser *parser;
+};
+
+/**
+ * cmp_key: Comparator for the nodes within the parser tree by key
+ * @key: Supplies a the key to evaluate nodes against
+ * @n: Supplies a pointer to the node to compare.
+ *
+ * Return:
+ * <0 - @key is to the left of @n
+ * 0 - @key identifies @n
+ * >0 - @key is to the right of @n
+ */
+static int cmp_key(const void *key, const struct rb_node *n)
+{
+	const struct parser_container *node;
+
+	node = container_of(n, struct parser_container, node);
+
+	return strcmp((const char *)key, node->parser->first_token);
+}
+
+/**
+ * cmp_node: Comparator for the nodes within the parser tree
+ * @n: Supplies a pointer to the node to compare
+ * @nn: Supplies a pointer to the another node to compare.
+ *
+ * Return:
+ * <0 - @n is lexigraphically before @nn
+ * 0 - @n is identical @nn
+ * >0 - @n is lexigraphically after @nn
+ */
+static int cmp_node(struct rb_node *n, const struct rb_node *nn)
+{
+	const struct parser_container *c1;
+	const struct parser_container *c2;
+
+	c1 = container_of(n, struct parser_container, node);
+	c2 = container_of(nn, struct parser_container, node);
+
+	return strcmp(c1->parser->first_token, c2->parser->first_token);
+}
+
+/**
+ * ipe_lookup_parser: Attempt to find a ipe_property structure by @first_token.
+ * @first_token: The key to look for in the tree.
+ *
+ * Return:
+ * !NULL - OK
+ * NULL - No property exists under @key
+ */
+const struct ipe_parser *ipe_lookup_parser(const char *first_token)
+{
+	struct rb_node *n;
+
+	n = rb_find(first_token, &ipe_parser_root, cmp_key);
+	if (!n)
+		return NULL;
+
+	return container_of(n, struct parser_container, node)->parser;
+}
+
+/**
+ * ipe_for_each_parser: Iterate over all currently-registered parsers
+ *			calling @fn on the values, and providing @view @ctx.
+ * @view: The function to call for each property. This is given the property
+ *	  structure as the first argument, and @ctx as the second.
+ * @ctx: caller-specified context that is passed to the function. Can be NULL.
+ *
+ * Return:
+ * 0 - OK
+ * !0 - Proper errno as returned by @view.
+ */
+int ipe_for_each_parser(int (*view)(const struct ipe_parser *parser,
+				    void *ctx),
+			void *ctx)
+{
+	int rc = 0;
+	struct rb_node *node;
+	struct parser_container *val;
+
+	for (node = rb_first(&ipe_parser_root); node; node = rb_next(node)) {
+		val = container_of(node, struct parser_container, node);
+
+		rc = view(val->parser, ctx);
+		if (rc)
+			return rc;
+	}
+
+	return rc;
+}
+
+/**
+ * ipe_register_parser: Register a parser to be used in IPE's policy.
+ * @p: Parser to register.
+ *
+ * This function allows parsers (policy constructs that effect IPE's
+ * internal functionality) to be leveraged in IPE policy. This must
+ * be called prior to any policies being loaded.
+ *
+ * Return:
+ * 0 - OK
+ * !0 - Error
+ */
+int ipe_register_parser(struct ipe_parser *p)
+{
+	struct rb_node *n = NULL;
+	struct parser_container *c = NULL;
+
+	c = kzalloc(sizeof(*c), GFP_KERNEL);
+	if (!c)
+		return -ENOMEM;
+
+	c->parser = p;
+
+	n = rb_find_add(&c->node, &ipe_parser_root, cmp_node);
+	if (n) {
+		kfree(c);
+		return -EEXIST;
+	}
+
+	return 0;
+}
diff --git a/security/ipe/parsers/Makefile b/security/ipe/parsers/Makefile
new file mode 100644
index 000000000000..1a19a094724f
--- /dev/null
+++ b/security/ipe/parsers/Makefile
@@ -0,0 +1,12 @@ 
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) Microsoft Corporation. All rights reserved.
+#
+# Makefile for building the IPE module as part of the kernel tree.
+#
+
+ccflags-y := -I$(srctree)/security/ipe
+
+obj-$(CONFIG_SECURITY_IPE) += \
+	default.o \
+	policy_header.o \
diff --git a/security/ipe/parsers/default.c b/security/ipe/parsers/default.c
new file mode 100644
index 000000000000..30181d2cc4ed
--- /dev/null
+++ b/security/ipe/parsers/default.c
@@ -0,0 +1,106 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+
+#include "ipe_parser.h"
+
+static int set_op_default(enum ipe_operation op, enum ipe_action act,
+			  struct ipe_parsed_policy *pol)
+{
+	size_t i, remap_len;
+	const enum ipe_operation *remap;
+
+	if (!ipe_is_op_alias(op, &remap, &remap_len)) {
+		if (pol->rules[op].default_action != ipe_action_max)
+			return -EBADMSG;
+
+		pol->rules[op].default_action = act;
+		return 0;
+	}
+
+	for (i = 0; i < remap_len; ++i) {
+		if (pol->rules[remap[i]].default_action != ipe_action_max)
+			return -EBADMSG;
+
+		pol->rules[remap[i]].default_action = act;
+	}
+
+	return 0;
+}
+
+static int parse_default(const struct ipe_policy_line *line,
+			 struct ipe_parsed_policy *pol)
+{
+	int rc = 0;
+	size_t idx = 0;
+	struct ipe_policy_token *tok = NULL;
+	enum ipe_operation op = ipe_operation_max;
+	enum ipe_action act = ipe_action_max;
+
+	list_for_each_entry(tok, &line->tokens, next) {
+		switch (idx) {
+		case 0:
+			if (strcmp("DEFAULT", tok->key) || tok->value)
+				return -EBADMSG;
+			break;
+		case 1:
+			/* schema 1 - operation, followed by action */
+			rc = ipe_parse_op(tok, &op);
+			if (!rc) {
+				++idx;
+				continue;
+			}
+
+			if (pol->global_default != ipe_action_max)
+				return -EBADMSG;
+
+			/* schema 2 - action */
+			rc = ipe_parse_action(tok, &pol->global_default);
+			if (!rc)
+				return rc;
+
+			return -EBADMSG;
+		case 2:
+			rc = ipe_parse_action(tok, &act);
+			if (rc)
+				return rc;
+
+			return set_op_default(op, act, pol);
+		default:
+			return -EBADMSG;
+		}
+		++idx;
+	}
+
+	/* met no schema */
+	return -EBADMSG;
+}
+
+static int validate_defaults(const struct ipe_parsed_policy *p)
+{
+	size_t i = 0;
+
+	if (p->global_default != ipe_action_max)
+		return 0;
+
+	for (i = 0; i < ARRAY_SIZE(p->rules); ++i) {
+		if (p->rules[i].default_action == ipe_action_max)
+			return -EBADMSG;
+	}
+
+	return 0;
+}
+
+IPE_PARSER(default_decl) = {
+	.first_token = "DEFAULT",
+	.version = 1,
+	.parse = parse_default,
+	.free = NULL,
+	.validate = validate_defaults,
+};
diff --git a/security/ipe/parsers/policy_header.c b/security/ipe/parsers/policy_header.c
new file mode 100644
index 000000000000..4d3c1a42c915
--- /dev/null
+++ b/security/ipe/parsers/policy_header.c
@@ -0,0 +1,126 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+
+#include "ipe.h"
+#include "ipe_parser.h"
+
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+
+#include "ipe_parser.h"
+
+static int parse_name(const struct ipe_policy_token *t,
+		      struct ipe_parsed_policy *p)
+{
+	if (p->name)
+		return -EBADMSG;
+
+	p->name = kstrdup_const(t->value, GFP_KERNEL);
+	if (!p->name)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int parse_ver(const struct ipe_policy_token *t,
+		     struct ipe_parsed_policy *p)
+{
+	int rc = 0;
+	char *dup = NULL;
+	char *dup2 = NULL;
+	char *token = NULL;
+	size_t sep_count = 0;
+	u16 *const cv[] = { &p->version.major, &p->version.minor, &p->version.rev };
+
+	dup = kstrdup(t->value, GFP_KERNEL);
+	if (!dup) {
+		rc = -ENOMEM;
+		goto err;
+	}
+
+	dup2 = dup;
+
+	while ((token = strsep(&dup, ".\n")) != NULL) {
+		/* prevent overflow */
+		if (sep_count >= ARRAY_SIZE(cv)) {
+			rc = -EBADMSG;
+			goto err;
+		}
+
+		rc = kstrtou16(token, 10, cv[sep_count]);
+		if (rc)
+			goto err;
+
+		++sep_count;
+	}
+
+	/* prevent underflow */
+	if (sep_count != ARRAY_SIZE(cv))
+		rc = -EBADMSG;
+
+err:
+	kfree(dup2);
+	return rc;
+}
+
+static const struct ipe_token_parser parsers[] = {
+	{ .key = "policy_name", .parse_token = parse_name },
+	{ .key = "policy_version", .parse_token = parse_ver },
+};
+
+static int parse_policy_hdr(const struct ipe_policy_line *line,
+			    struct ipe_parsed_policy *pol)
+{
+	int rc = 0;
+	size_t idx = 0;
+	struct ipe_policy_token *tok = NULL;
+	const struct ipe_token_parser *p = NULL;
+
+	list_for_each_entry(tok, &line->tokens, next) {
+		if (!tok->value || idx >= sizeof(parsers)) {
+			rc = -EBADMSG;
+			goto err;
+		}
+
+		p = &parsers[idx];
+
+		if (strcmp(p->key, tok->key)) {
+			rc = -EBADMSG;
+			goto err;
+		}
+
+		rc = p->parse_token(tok, pol);
+		if (rc)
+			goto err;
+
+		++idx;
+	}
+
+	return 0;
+
+err:
+	return rc;
+}
+
+static int free_policy_hdr(struct ipe_parsed_policy *pol)
+{
+	kfree(pol->name);
+	return 0;
+}
+
+static int validate_policy_hdr(const struct ipe_parsed_policy *p)
+{
+	return !p->name ? -EBADMSG : 0;
+}
+
+IPE_PARSER(policy_header) = {
+	.first_token = "policy_name",
+	.version = 1,
+	.parse = parse_policy_hdr,
+	.free = free_policy_hdr,
+	.validate = validate_policy_hdr,
+};
diff --git a/security/ipe/policy.c b/security/ipe/policy.c
new file mode 100644
index 000000000000..6381fa7c2ec6
--- /dev/null
+++ b/security/ipe/policy.c
@@ -0,0 +1,946 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+
+#include "ipe.h"
+#include "policy.h"
+#include "ipe_parser.h"
+#include "modules.h"
+
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/ctype.h>
+#include <linux/types.h>
+#include <linux/parser.h>
+#include <linux/verification.h>
+
+#define START_COMMENT	'#'
+#define KEYVAL_DELIMIT	'='
+
+static inline bool is_quote(char ch)
+{
+	return ch == '\'' || ch == '\"';
+}
+
+/**
+ * is_key_char: Determine whether @ch is an acceptable character for a
+ *		key type
+ * @ch: Supplies the character to evaluate.
+ *
+ * Return:
+ * true - Character is acceptable.
+ * false - Character is not acceptable.
+ */
+static inline bool is_key_char(char ch)
+{
+	return isalnum(ch) || ch == '_';
+}
+
+/**
+ * is_val_char: Determine whether @ch is an acceptable character for a
+ *		value type
+ * @ch: Supplies the character to evaluate.
+ *
+ * Return:
+ * true - Character is acceptable.
+ * false - Character is not acceptable.
+ */
+static inline bool is_val_char(char ch)
+{
+	return isgraph(ch) || ch == ' ' || ch == '\t';
+}
+
+/**
+ * free_parser: Callback to invoke, freeing data allocated by parsers.
+ * @parser: parser to free data.
+ * @ctx: ctx object passed to ipe_for_each_parser.
+ *
+ * This function is intended to be used with ipe_for_each_parser only.
+ *
+ * Return:
+ * 0 - Always
+ */
+static int free_parser(const struct ipe_parser *parser, void *ctx)
+{
+	struct ipe_parsed_policy *pol = ctx;
+
+	if (parser->free)
+		parser->free(pol);
+
+	return 0;
+}
+
+/**
+ * free_rule: free an ipe_rule.
+ * @r: Supplies the rule to free.
+ *
+ * This function is safe to call if @r is NULL or ERR_PTR.
+ */
+static void free_rule(struct ipe_rule *r)
+{
+	struct ipe_policy_mod *p, *t;
+
+	if (IS_ERR_OR_NULL(r))
+		return;
+
+	list_for_each_entry_safe(p, t, &r->modules, next) {
+		if (p->mod->free)
+			p->mod->free(&p->mod_value);
+
+		kfree(p);
+	}
+
+	kfree(r);
+}
+
+static void free_parsed_policy(struct ipe_parsed_policy *p)
+{
+	size_t i = 0;
+	struct ipe_rule *pp, *t;
+
+	if (IS_ERR_OR_NULL(p))
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(p->rules); ++i)
+		list_for_each_entry_safe(pp, t, &p->rules[i].rules, next)
+			free_rule(pp);
+
+	(void)ipe_for_each_parser(free_parser, p);
+	kfree(p);
+}
+
+/**
+ * free_parsed_line: free a single parsed line of tokens.
+ * @line: Supplies the line to free.
+ *
+ * This function is safe to call if @line is NULL or ERR_PTR.
+ */
+static void free_parsed_line(struct ipe_policy_line *line)
+{
+	struct ipe_policy_token *p, *t;
+
+	if (IS_ERR_OR_NULL(line))
+		return;
+
+	list_for_each_entry_safe(p, t, &line->tokens, next)
+		kfree(p);
+}
+
+/**
+ * free_parsed_text: free a 2D list representing a tokenized policy.
+ * @parsed: Supplies the policy to free.
+ *
+ * This function is safe to call if @parsed is NULL or ERR_PTR.
+ */
+static void free_parsed_text(struct list_head *parsed)
+{
+	struct ipe_policy_line *p, *t;
+
+	if (IS_ERR_OR_NULL(parsed))
+		return;
+
+	list_for_each_entry_safe(p, t, parsed, next)
+		free_parsed_line(p);
+}
+
+/**
+ * trim_quotes: Edit @str to remove a single instance of a trailing and
+ *		leading quotes.
+ * @str: Supplies the string to edit.
+ *
+ * If the string is not quoted, @str will be returned. This function is
+ * safe to call if @str is NULL.
+ *
+ * Return:
+ * !0 - OK
+ * ERR_PTR(-EBADMSG) - Quote mismatch.
+ */
+static char *trim_quotes(char *str)
+{
+	char s;
+	size_t len;
+
+	if (!str)
+		return str;
+
+	s = *str;
+
+	if (is_quote(s)) {
+		len = strlen(str) - 1;
+
+		if (str[len] != s)
+			return ERR_PTR(-EBADMSG);
+
+		str[len] = '\0';
+		++str;
+	}
+
+	return str;
+}
+
+/**
+ * parse_token: Parse a string into a proper token representation.
+ * @token: Supplies the token string to parse.
+ *
+ * @token will be edited destructively. Pass a copy if you wish to retain
+ * the state of the original.
+ *
+ * This function will emit an error to pr_err when a parsing error occurs.
+ *
+ * Return:
+ * !0 - OK
+ * ERR_PTR(-EBADMSG) - An invalid character was encountered while parsing.
+ * ERR_PTR(-ENOMEM) - No Memory
+ */
+static struct ipe_policy_token *parse_token(char *token)
+{
+	size_t i, len = 0;
+	char *key = token;
+	char *value = NULL;
+	struct ipe_policy_token *local = NULL;
+
+	len = strlen(token);
+
+	for (i = 0; (i < len) && token[i] != KEYVAL_DELIMIT; ++i)
+		if (!is_key_char(token[i]))
+			return ERR_PTR(-EBADMSG);
+
+	token[i] = '\0';
+	++i;
+
+	/* there is a value */
+	if (i < len) {
+		value = trim_quotes(&token[i]);
+		if (IS_ERR(value))
+			return ERR_PTR(-EBADMSG);
+
+		len = strlen(value);
+
+		for (i = 0; i < len; ++i)
+			if (!is_val_char(value[i]))
+				return ERR_PTR(-EBADMSG);
+	}
+
+	local = kzalloc(sizeof(*local), GFP_KERNEL);
+	if (!local)
+		return ERR_PTR(-ENOMEM);
+
+	INIT_LIST_HEAD(&local->next);
+	local->key = key;
+	local->value = value;
+
+	return local;
+}
+
+/**
+ * append_token: Parse and append a token into an ipe_policy_line structure.
+ * @p: Supplies the ipe_policy_line structure to append to.
+ * @token: Supplies the token to parse and append to.
+ *
+ * @token will be edited during the parsing destructively. Pass a copy if you
+ * wish to retain the original.
+ *
+ * Return:
+ * 0 - OK
+ * -EBADMSG - Parsing error of @token
+ */
+static int append_token(struct ipe_policy_line *p, char *token)
+{
+	struct ipe_policy_token *t = NULL;
+
+	t = parse_token(token);
+	if (IS_ERR(t))
+		return PTR_ERR(t);
+
+	list_add_tail(&t->next, &p->tokens);
+
+	return 0;
+}
+
+/**
+ * alloc_line: Allocate an ipe_policy_line structure.
+ *
+ * Return:
+ * !0 - OK
+ * -EBADMSG - Parsing error of @token
+ */
+static struct ipe_policy_line *alloc_line(void)
+{
+	struct ipe_policy_line *l = NULL;
+
+	l = kzalloc(sizeof(*l), GFP_KERNEL);
+	if (!l)
+		return ERR_PTR(-ENOMEM);
+
+	INIT_LIST_HEAD(&l->next);
+	INIT_LIST_HEAD(&l->tokens);
+
+	return l;
+}
+
+/**
+ * insert_token: Append a token to @line.
+ * @token: Supplies the token to append to @line.
+ * @line: Supplies a pointer to the ipe_policy_line structure to append to.
+ *
+ * If @line is NULL, it will be allocated on behalf of the caller.
+ *
+ * Return:
+ * 0 - OK
+ * -ENOMEM - No Memory
+ * -EBADMSG - Parsing error of @token
+ */
+static int insert_token(char *token, struct ipe_policy_line **line)
+{
+	int rc = 0;
+	struct ipe_policy_line *local = *line;
+
+	if (!local) {
+		local = alloc_line();
+		if (IS_ERR(local))
+			return PTR_ERR(local);
+
+		*line = local;
+	}
+
+	rc = append_token(local, token);
+	if (rc)
+		return rc;
+
+	return 0;
+}
+
+/**
+ * ipe_tokenize_line: Parse a line of text into a list of token structures.
+ * @line: Supplies the line to parse.
+ *
+ * The final result can be NULL, which represents no tokens were parsed.
+ *
+ * Return:
+ * !0 - OK
+ * NULL - OK, no tokens were parsed.
+ * ERR_PTR(-EBADMSG) - Invalid policy syntax
+ * ERR_PTR(-ENOMEM) - No Memory
+ */
+static struct ipe_policy_line *tokenize_line(char *line)
+{
+	int rc = 0;
+	size_t i = 0;
+	size_t len = 0;
+	char *tok = NULL;
+	char quote = '\0';
+	struct ipe_policy_line *p = NULL;
+
+	/* nullterm guaranteed by strsep */
+	len = strlen(line);
+
+	for (i = 0; i < len; ++i) {
+		if (quote == '\0' && is_quote(line[i])) {
+			quote = line[i];
+			continue;
+		}
+
+		if (quote != '\0' && line[i] == quote) {
+			quote = '\0';
+			continue;
+		}
+
+		if (quote == '\0' && line[i] == START_COMMENT) {
+			tok = NULL;
+			break;
+		}
+
+		if (isgraph(line[i]) && !tok)
+			tok = &line[i];
+
+		if (quote == '\0' && isspace(line[i])) {
+			line[i] = '\0';
+
+			if (!tok)
+				continue;
+
+			rc = insert_token(tok, &p);
+			if (rc)
+				goto err;
+
+			tok = NULL;
+		}
+	}
+
+	if (quote != '\0') {
+		rc = -EBADMSG;
+		goto err;
+	}
+
+	if (tok) {
+		rc = insert_token(tok, &p);
+		if (rc)
+			goto err;
+	}
+
+	return p;
+
+err:
+	free_parsed_line(p);
+	return ERR_PTR(rc);
+}
+
+/**
+ * parse_pass1: parse @policy into a 2D list, representing tokens on each line.
+ * @policy: Supplies the policy to parse. Must be nullterminated, and is
+ *	    edited.
+ *
+ * In pass1 of the parser, the policy is tokenized. Minor structure checks
+ * are done (mismatching quotes, invalid characters).
+ *
+ * Caller must maintain the lifetime of @policy while the return value is
+ * alive.
+ *
+ * Return:
+ * !0 - OK
+ * ERR_PTR(-ENOMEM) - Out of Memory
+ * ERR_PTR(-EBADMSG) - Parsing Error
+ */
+static int parse_pass1(char *policy, struct list_head *tokens)
+{
+	int rc = 0;
+	char *p = NULL;
+
+	while ((p = strsep(&policy, "\n\0")) != NULL) {
+		struct ipe_policy_line *t = NULL;
+
+		t = tokenize_line(p);
+		if (IS_ERR(t)) {
+			rc = PTR_ERR(t);
+			goto err_free_parsed;
+		}
+
+		if (!t)
+			continue;
+
+		list_add_tail(&t->next, tokens);
+	}
+
+	return 0;
+
+err_free_parsed:
+	free_parsed_text(tokens);
+	return rc;
+}
+
+/**
+ * parse_pass2: Take the 2D list of tokens generated from pass1, and transform
+ *		it into a partial ipe_policy.
+ * @parsed: Supplies the list of tokens generated from pass1.
+ * @p: Policy to manipulate with parsed tokens.
+ *
+ * This function is where various declarations and references are parsed into
+ * policy. All declarations and references required to parse rules should be
+ * done here as a parser, and then in pass3 these can be utilized.
+ *
+ * Return:
+ * !0 - OK
+ * -EBADMSG - Syntax Parsing Errors
+ * -ENOENT - No handler for a token.
+ * -ENOMEM - Out of memory
+ */
+static int parse_pass2(struct list_head *parsed, struct ipe_parsed_policy *pol)
+{
+	int rc = 0;
+	const struct ipe_parser *p = NULL;
+	struct ipe_policy_line *line = NULL;
+	const struct ipe_policy_token *token = NULL;
+
+	list_for_each_entry(line, parsed, next) {
+		token = list_first_entry(&line->tokens, struct ipe_policy_token, next);
+		p = ipe_lookup_parser(token->key);
+		if (!p)
+			continue;
+
+		rc = p->parse(line, pol);
+		if (rc)
+			return rc;
+
+		line->consumed = true;
+	}
+
+	return rc;
+}
+
+/**
+ * ipe_parse_op: parse a token to an operation value.
+ * @tok: Token to parse
+ * @op: Operation Parsed.
+ *
+ * Return:
+ * 0 - OK
+ * -EINVAL - Invalid key or value.
+ */
+int ipe_parse_op(const struct ipe_policy_token *tok,
+		 enum ipe_operation *op)
+{
+	substring_t match[MAX_OPT_ARGS] = { 0 };
+	const match_table_t ops = {
+		{ ipe_op_alias_max, NULL },
+	};
+
+	if (strcmp(tok->key, "op") || !tok->value)
+		return -EINVAL;
+
+	*op = match_token((char *)tok->value, ops, match);
+	if ((*op) == (int)ipe_op_alias_max)
+		return -ENOENT;
+
+	return 0;
+}
+
+/**
+ * ipe_parse_action: parse a token to an operation value.
+ * @tok: Token to parse
+ * @action: action parsed.
+ *
+ * Return:
+ * 0 - OK
+ * -EINVAL - Invalid key or value.
+ */
+int ipe_parse_action(const struct ipe_policy_token *tok,
+		     enum ipe_action *action)
+{
+	substring_t match[MAX_OPT_ARGS] = { 0 };
+	const match_table_t actions = {
+		{ ipe_action_allow, "ALLOW" },
+		{ ipe_action_deny, "DENY" },
+		{ ipe_action_max, NULL },
+	};
+
+	if (strcmp(tok->key, "action") || !tok->value)
+		return -EINVAL;
+
+	*action = match_token((char *)tok->value, actions, match);
+
+	if (*action == ipe_action_max)
+		return -EINVAL;
+
+	return 0;
+}
+
+/**
+ * parse_mod_to_rule: Parse a module token and append the values to the
+ *		      provided rule.
+ * @t: Supplies the token to parse.
+ * @r: Supplies the rule to modify with the result.
+ *
+ * Return:
+ * 0 - OK
+ * -ENOENT - No such module to handle @t.
+ * -ENOMEM - No memory.
+ * Others - Module defined errors.
+ */
+static int parse_mod_to_rule(const struct ipe_policy_token *t, struct ipe_rule *r)
+{
+	int rc = 0;
+	struct ipe_policy_mod *p = NULL;
+	const struct ipe_module *m = NULL;
+
+	m = ipe_lookup_module(t->key);
+	if (IS_ERR_OR_NULL(m)) {
+		rc = (m) ? PTR_ERR(m) : -ENOENT;
+		goto err;
+	}
+
+	p = kzalloc(sizeof(*p), GFP_KERNEL);
+	if (!p) {
+		rc = -ENOMEM;
+		goto err;
+	}
+	INIT_LIST_HEAD(&p->next);
+	p->mod = m;
+
+	rc = m->parse(t->value, &p->mod_value);
+	if (rc)
+		goto err2;
+
+	list_add_tail(&p->next, &r->modules);
+	return 0;
+err2:
+	kfree(p);
+err:
+	return rc;
+}
+
+/**
+ * parse_rule: Parse a policy line into an ipe_rule structure.
+ * @line: Supplies the line to parse.
+ *
+ * Return:
+ * Valid ipe_rule - OK
+ * ERR_PTR(-ENOMEM) - Out of Memory
+ * ERR_PTR(-ENOENT) - No such module to handle a token
+ * ERR_PTR(-EINVAL) - An unacceptable value has been encountered.
+ * ERR_PTR(...) - Module defined errors.
+ */
+static struct ipe_rule *parse_rule(const struct ipe_policy_line *line)
+{
+	int rc = 0;
+	struct ipe_rule *r = NULL;
+	const struct list_head *node = NULL;
+
+	r = kzalloc(sizeof(*r), GFP_KERNEL);
+	if (!r) {
+		rc = -ENOMEM;
+		goto err;
+	}
+
+	INIT_LIST_HEAD(&r->next);
+	INIT_LIST_HEAD(&r->modules);
+	r->op = (int)ipe_op_alias_max;
+	r->action = ipe_action_max;
+
+	list_for_each(node, &line->tokens) {
+		const struct ipe_policy_token *token = NULL;
+
+		token = container_of(node, struct ipe_policy_token, next);
+
+		if (list_is_first(node, &line->tokens)) {
+			enum ipe_operation op;
+
+			rc = ipe_parse_op(token, &op);
+			if (rc)
+				goto err;
+
+			r->op = op;
+			continue;
+		}
+
+		if (list_is_last(node, &line->tokens)) {
+			enum ipe_action action;
+
+			rc = ipe_parse_action(token, &action);
+			if (rc)
+				goto err;
+
+			r->action = action;
+			continue;
+		}
+
+		rc = parse_mod_to_rule(token, r);
+		if (rc)
+			goto err;
+	}
+
+	if (r->action == ipe_action_max || r->op == (int)ipe_op_alias_max) {
+		rc = -EBADMSG;
+		goto err;
+	}
+
+	return r;
+err:
+	free_rule(r);
+	return ERR_PTR(rc);
+}
+
+/**
+ * parse_pass3: Take the partially parsed list of tokens from pass 1 and the
+ *		parial policy from pass 2, and finalize the policy.
+ * @parsed: Supplies the tokens parsed from pass 1.
+ * @p: Supplies the partial policy from pass 2.
+ *
+ * This function finalizes the IPE policy by parsing all rules in the
+ * policy. This must occur in pass3, as in pass2, references are resolved
+ * that can be used in pass3.
+ *
+ * Return:
+ * 0 - OK
+ * !0 - Standard errno
+ */
+static int parse_pass3(struct list_head *parsed,
+		       struct ipe_parsed_policy *p)
+{
+	int rc = 0;
+	size_t i = 0;
+	size_t remap_len = 0;
+	struct ipe_rule *rule = NULL;
+	struct ipe_policy_line *line = NULL;
+	const enum ipe_operation *remap;
+
+	list_for_each_entry(line, parsed, next) {
+		if (line->consumed)
+			continue;
+
+		rule = parse_rule(line);
+		if (IS_ERR(rule)) {
+			rc = PTR_ERR(rule);
+			goto err;
+		}
+
+		if (ipe_is_op_alias(rule->op, &remap, &remap_len)) {
+			for (i = 0; i < remap_len; ++i) {
+				rule->op = remap[i];
+				list_add_tail(&rule->next, &p->rules[rule->op].rules);
+				rule = parse_rule(line);
+			}
+
+			free_rule(rule);
+		} else {
+			list_add_tail(&rule->next, &p->rules[rule->op].rules);
+		}
+
+		line->consumed = true;
+	}
+
+	return 0;
+err:
+	free_rule(rule);
+	return rc;
+}
+
+/**
+ * parser_validate: Callback to invoke, validating parsers as necessary
+ * @parser: parser to call to validate data.
+ * @ctx: ctx object passed to ipe_for_each_parser.
+ *
+ * This function is intended to be used with ipe_for_each_parser only.
+ *
+ * Return:
+ * 0 - OK
+ * !0 - Validation failed.
+ */
+static int parser_validate(const struct ipe_parser *parser, void *ctx)
+{
+	int rc = 0;
+	const struct ipe_parsed_policy *pol = ctx;
+
+	if (parser->validate)
+		rc = parser->validate(pol);
+
+	return rc;
+}
+
+/**
+ * validate_policy: Given a policy structure that was just parsed, validate
+ *		    that all necessary fields are present, initialized
+ *		    correctly, and all lines parsed are have been consumed.
+ * @parsed: Supplies the policy lines that were parsed in pass1.
+ * @policy: Supplies the fully parsed policy.
+ *
+ * A parsed policy can be an invalid state for use (a default was undefined,
+ * a header was undefined) by just parsing the policy.
+ *
+ * Return:
+ * 0 - OK
+ * -EBADMSG - Policy is invalid.
+ */
+static int validate_policy(const struct list_head *parsed,
+			   const struct ipe_parsed_policy *p)
+{
+	int rc = 0;
+	const struct ipe_policy_line *line = NULL;
+
+	list_for_each_entry(line, parsed, next) {
+		if (!line->consumed)
+			return -EBADMSG;
+	}
+
+	rc = ipe_for_each_parser(parser_validate,
+				 (struct ipe_parsed_policy *)p);
+
+	return rc;
+}
+
+/**
+ * new_parsed_policy: Allocate and initialize a parsed policy to its default
+ *		      values.
+ *
+ * Return:
+ * !IS_ERR - OK
+ */
+static struct ipe_parsed_policy *new_parsed_policy(void)
+{
+	size_t i = 0;
+	struct ipe_parsed_policy *p = NULL;
+	struct ipe_operation_table *t = NULL;
+
+	p = kzalloc(sizeof(*p), GFP_KERNEL);
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+
+	p->global_default = ipe_action_max;
+
+	for (i = 0; i < ARRAY_SIZE(p->rules); ++i) {
+		t = &p->rules[i];
+
+		t->default_action = ipe_action_max;
+		INIT_LIST_HEAD(&t->rules);
+	}
+
+	return p;
+}
+
+/**
+ * parse_policy: Given a string, parse the string into an IPE policy
+ *		     structure.
+ * @p: partially filled ipe_policy structure to populate with the result.
+ *
+ * @p must have text and textlen set.
+ *
+ * Return:
+ * Valid ipe_policy structure - OK
+ * ERR_PTR(-EBADMSG) - Invalid Policy Syntax (Unrecoverable)
+ * ERR_PTR(-ENOMEM) - Out of Memory
+ */
+static int parse_policy(struct ipe_policy *p)
+{
+	int rc = 0;
+	char *dup = NULL;
+	LIST_HEAD(parsed);
+	struct ipe_parsed_policy *pp = NULL;
+
+	if (!p->textlen)
+		return -EBADMSG;
+
+	dup = kmemdup_nul(p->text, p->textlen, GFP_KERNEL);
+	if (!dup)
+		return -ENOMEM;
+
+	pp = new_parsed_policy();
+	if (IS_ERR(pp)) {
+		rc = PTR_ERR(pp);
+		goto out;
+	}
+
+	rc = parse_pass1(dup, &parsed);
+	if (rc)
+		goto err;
+
+	rc = parse_pass2(&parsed, pp);
+	if (rc)
+		goto err;
+
+	rc = parse_pass3(&parsed, pp);
+	if (rc)
+		goto err;
+
+	rc = validate_policy(&parsed, pp);
+	if (rc)
+		goto err;
+
+	p->parsed = pp;
+
+	goto out;
+err:
+	free_parsed_policy(pp);
+out:
+	free_parsed_text(&parsed);
+	kfree(dup);
+
+	return rc;
+}
+
+/**
+ * ipe_is_op_alias: Determine if @op is an alias for one or more operations
+ * @op: Supplies the operation to check. Should be either ipe_operation or
+ *	ipe_op_alias.
+ * @map: Supplies a pointer to populate with the mapping if @op is an alias
+ * @size: Supplies the size of @map if @op is an alias.
+ *
+ * Return:
+ * true - @op is an alias
+ * false - @op is not an alias
+ */
+bool ipe_is_op_alias(int op, const enum ipe_operation **map, size_t *size)
+{
+	switch (op) {
+	default:
+		return false;
+	}
+}
+
+/**
+ * ipe_put_policy: Deallocate a given IPE policy.
+ * @p: Supplies the policy to free.
+ *
+ * Safe to call on IS_ERR/NULL.
+ */
+void ipe_put_policy(struct ipe_policy *p)
+{
+	if (IS_ERR_OR_NULL(p) || !refcount_dec_and_test(&p->refcount))
+		return;
+
+	free_parsed_policy(p->parsed);
+	if (!p->pkcs7)
+		kfree(p->text);
+	kfree(p->pkcs7);
+	kfree(p);
+}
+
+static int set_pkcs7_data(void *ctx, const void *data, size_t len,
+			  size_t asn1hdrlen)
+{
+	struct ipe_policy *p = ctx;
+
+	p->text = (const char *)data;
+	p->textlen = len;
+
+	return 0;
+}
+
+/**
+ * ipe_new_policy: allocate and parse an ipe_policy structure.
+ *
+ * @text: Supplies a pointer to the plain-text policy to parse.
+ * @textlen: Supplies the length of @text.
+ * @pkcs7: Supplies a pointer to a pkcs7-signed IPE policy.
+ * @pkcs7len: Supplies the length of @pkcs7.
+ *
+ * @text/@textlen Should be NULL/0 if @pkcs7/@pkcs7len is set.
+ *
+ * The result will still need to be associated with a context via
+ * ipe_add_policy.
+ *
+ * Return:
+ * !IS_ERR - Success
+ */
+struct ipe_policy *ipe_new_policy(const char *text, size_t textlen,
+				  const char *pkcs7, size_t pkcs7len)
+{
+	int rc = 0;
+	struct ipe_policy *new = NULL;
+
+	new = kzalloc(sizeof(*new), GFP_KERNEL);
+	if (!new)
+		return ERR_PTR(-ENOMEM);
+
+	refcount_set(&new->refcount, 1);
+
+	if (!text) {
+		new->pkcs7len = pkcs7len;
+		new->pkcs7 = kmemdup(pkcs7, pkcs7len, GFP_KERNEL);
+		if (!new->pkcs7) {
+			rc = -ENOMEM;
+			goto err;
+		}
+
+		rc = verify_pkcs7_signature(NULL, 0, new->pkcs7, pkcs7len, NULL,
+					    VERIFYING_UNSPECIFIED_SIGNATURE,
+					    set_pkcs7_data, new);
+		if (rc)
+			goto err;
+	} else {
+		new->textlen = textlen;
+		new->text = kstrndup(text, textlen, GFP_KERNEL);
+		if (!new->text) {
+			rc = -ENOMEM;
+			goto err;
+		}
+	}
+
+	rc = parse_policy(new);
+	if (rc)
+		goto err;
+
+	return new;
+err:
+	ipe_put_policy(new);
+	return ERR_PTR(rc);
+}
diff --git a/security/ipe/policy.h b/security/ipe/policy.h
new file mode 100644
index 000000000000..d78788db238c
--- /dev/null
+++ b/security/ipe/policy.h
@@ -0,0 +1,97 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+#ifndef IPE_POLICY_H
+#define IPE_POLICY_H
+
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/refcount.h>
+
+struct ipe_policy_token {
+	struct list_head next;		/* type: policy_token */
+
+	const char *key;
+	const char *value;
+};
+
+struct ipe_policy_line {
+	struct list_head next;		/* type: policy_line */
+	struct list_head tokens;	/* type: policy_token */
+
+	bool consumed;
+};
+
+struct ipe_module;
+
+enum ipe_operation {
+	ipe_operation_max = 0,
+};
+
+/*
+ * Extension to ipe_operation, representing operations
+ * that are just one or more operations under the hood
+ */
+enum ipe_op_alias {
+	ipe_op_alias_max = ipe_operation_max,
+};
+
+enum ipe_action {
+	ipe_action_allow = 0,
+	ipe_action_deny,
+	ipe_action_max,
+};
+
+struct ipe_policy_mod {
+	const struct ipe_module *mod;
+	void			*mod_value;
+
+	struct list_head next;
+};
+
+struct ipe_rule {
+	enum ipe_operation op;
+	enum ipe_action action;
+
+	struct list_head modules;
+
+	struct list_head next;
+};
+
+struct ipe_operation_table {
+	struct list_head rules;
+	enum ipe_action default_action;
+};
+
+struct ipe_parsed_policy {
+	const char *name;
+	struct {
+		u16 major;
+		u16 minor;
+		u16 rev;
+	} version;
+
+	enum ipe_action global_default;
+
+	struct ipe_operation_table rules[ipe_operation_max];
+};
+
+struct ipe_policy {
+	const char     *pkcs7;
+	size_t		pkcs7len;
+
+	const char     *text;
+	size_t		textlen;
+
+	struct ipe_parsed_policy *parsed;
+
+	refcount_t	refcount;
+};
+
+struct ipe_policy *ipe_new_policy(const char *text, size_t textlen,
+				  const char *pkcs7, size_t pkcs7len);
+void ipe_put_policy(struct ipe_policy *pol);
+bool ipe_is_op_alias(int op, const enum ipe_operation **map, size_t *size);
+
+#endif /* IPE_POLICY_H */