RE: [RFC PATCH v7 04/16] ipe: add userspace interface

[Roberto Sassu]

> From: deven.desai@xxxxxxxxxxxxxxxxxxx
> [mailto:deven.desai@xxxxxxxxxxxxxxxxxxx]
> From: Deven Bowers <deven.desai@xxxxxxxxxxxxxxxxxxx>
> 
> As is typical with LSMs, IPE uses securityfs as its interface with
> userspace. for a complete list of the interfaces and the respective
> inputs/outputs, please see the documentation under
> admin-guide/LSM/ipe.rst
> 
> Signed-off-by: Deven Bowers <deven.desai@xxxxxxxxxxxxxxxxxxx>
> ---
> 
> Relevant changes since v6:
>   * Refactor series to:
>       1. Support a context structure, enabling easier testing
>   * Split up patch 03/12 into two parts:
>       1. parser [02/16]
>       2. userspace interface [04/16] (this patch)
>   * Interface changes:
>       1. "raw" was renamed to "pkcs7" and made read only
>       2. "raw"'s write functionality (update a policy) moved to "update"
>       3. introduced "version", "policy_name" nodes.
>       4. "content" renamed to "policy"
>       5. The boot policy can now be updated like any other policy.
> 
> ---
>  security/ipe/Makefile   |   2 +
>  security/ipe/ctx.c      | 121 +++++++++
>  security/ipe/ctx.h      |   6 +
>  security/ipe/fs.c       | 170 +++++++++++++
>  security/ipe/fs.h       |  13 +
>  security/ipe/policy.c   |  41 ++++
>  security/ipe/policy.h   |   4 +
>  security/ipe/policyfs.c | 528 ++++++++++++++++++++++++++++++++++++++++
>  8 files changed, 885 insertions(+)
>  create mode 100644 security/ipe/fs.c
>  create mode 100644 security/ipe/fs.h
>  create mode 100644 security/ipe/policyfs.c
> 
> diff --git a/security/ipe/Makefile b/security/ipe/Makefile
> index 0db69f13e82a..d5660a17364c 100644
> --- a/security/ipe/Makefile
> +++ b/security/ipe/Makefile
> @@ -10,9 +10,11 @@ ccflags-y := -I$(srctree)/security/ipe/modules
>  obj-$(CONFIG_SECURITY_IPE) += \
>  	ctx.o \
>  	eval.o \
> +	fs.o \
>  	hooks.o \
>  	ipe.o \
>  	modules.o \
>  	parsers/ \
>  	parsers.o \
>  	policy.o \
> +	policyfs.o \
> diff --git a/security/ipe/ctx.c b/security/ipe/ctx.c
> index 9274e51eff52..664c671a4f9c 100644
> --- a/security/ipe/ctx.c
> +++ b/security/ipe/ctx.c
> @@ -13,6 +13,29 @@
>  #include <linux/refcount.h>
>  #include <linux/spinlock.h>
> 
> +/**
> + * ver_to_u64: convert an internal ipe_policy_version to a u64
> + * @p: Policy to extract the version from
> + *
> + * Bits (LSB is index 0):
> + *	[48,32] -> Major
> + *	[32,16] -> Minor
> + *	[16, 0] -> Revision
> + *
> + * Return:
> + * u64 version of the embedded version structure.
> + */
> +static inline u64 ver_to_u64(const struct ipe_policy *const p)
> +{
> +	u64 r = 0;
> +
> +	r = (((u64)p->parsed->version.major) << 32)
> +	  | (((u64)p->parsed->version.minor) << 16)
> +	  | ((u64)(p->parsed->version.rev));
> +
> +	return r;
> +}
> +
>  /**
>   * ipe_current_ctx: Helper to retrieve the ipe_context for the current task.
>   *
> @@ -96,6 +119,7 @@ static void free_ctx_work(struct work_struct *const
> work)
>  	list_for_each_entry(p, &ctx->policies, next)
>  		ipe_put_policy(p);
> 
> +	securityfs_remove(ctx->policy_root);
>  	kfree(ctx);
>  }
> 
> @@ -160,6 +184,9 @@ void ipe_remove_policy(struct ipe_policy *p)
>   * ipe_add_policy: Associate @p with @ctx
>   * @ctx: Supplies a pointer to the ipe_context structure to associate @p with.
>   * @p: Supplies a pointer to the ipe_policy structure to associate.
> + *
> + * This will increase @p's reference count by one.
> + *
>   */
>  void ipe_add_policy(struct ipe_context *ctx, struct ipe_policy *p)
>  {
> @@ -168,7 +195,101 @@ void ipe_add_policy(struct ipe_context *ctx, struct
> ipe_policy *p)
>  	list_add_tail(&p->next, &ctx->policies);
>  	refcount_inc(&p->refcount);
>  	spin_unlock(&ctx->lock);
> +}
> +
> +/**
> + * ipe_replace_policy: Replace @old with @new in the list of policies in @ctx
> + * @ctx: Supplies the context object to manipulate.
> + * @old: Supplies a pointer to the ipe_policy to replace with @new
> + * @new: Supplies a pointer to the ipe_policy structure to replace @old with
> + */
> +int ipe_replace_policy(struct ipe_policy *old, struct ipe_policy *new)
> +{
> +	int rc = -EINVAL;
> +	struct ipe_context *ctx;
> +	struct ipe_policy *cursor;
> +	struct ipe_policy *p = NULL;
> +
> +	ctx = ipe_get_ctx_rcu(old->ctx);
> +	if (!ctx)
> +		return -ENOENT;
> +
> +	spin_lock(&ctx->lock);
> +	list_for_each_entry(cursor, &ctx->policies, next) {
> +		if (!strcmp(old->parsed->name, cursor->parsed->name)) {
> +			if (ipe_is_policy_active(old)) {
> +				if (ver_to_u64(old) > ver_to_u64(new))
> +					break;
> +				rcu_assign_pointer(ctx->active_policy, new);
> +			}
> +			list_replace_init(&cursor->next, &new->next);
> +			refcount_inc(&new->refcount);
> +			rcu_assign_pointer(new->ctx, old->ctx);
> +			p = cursor;
> +			rc = 0;
> +			break;
> +		}
> +	}
> +	spin_unlock(&ctx->lock);
> +	synchronize_rcu();
> +
> +	ipe_put_policy(p);
> +	ipe_put_ctx(ctx);
> +	return rc;
> +}
> +
> +/**
> + * ipe_set_active_pol: Make @p the active policy.
> + * @p: Supplies a pointer to the policy to make active.
> + */
> +int ipe_set_active_pol(const struct ipe_policy *p)
> +{
> +	int rc = 0;
> +	struct ipe_policy *ap = NULL;
> +	struct ipe_context *ctx = NULL;
> +
> +	ctx = ipe_get_ctx_rcu(p->ctx);
> +	if (!ctx) {
> +		rc = -ENOENT;
> +		goto out;
> +	}
> +
> +	ap = ipe_get_policy_rcu(ctx->active_policy);
> +	if (ap && ver_to_u64(ap) > ver_to_u64(p)) {
> +		rc = -EINVAL;
> +		goto out;
> +	}
> +
> +	spin_lock(&ctx->lock);
> +	rcu_assign_pointer(ctx->active_policy, p);
> +	spin_unlock(&ctx->lock);
>  	synchronize_rcu();
> +
> +out:
> +	ipe_put_policy(ap);
> +	ipe_put_ctx(ctx);
> +	return rc;
> +}
> +
> +/**
> + * ipe_is_policy_active: Determine wehther @p is the active policy
> + * @p: Supplies a pointer to the policy to check.
> + *
> + * Return:
> + * true - @p is the active policy of @ctx
> + * false - @p is not the active policy of @ctx
> + */
> +bool ipe_is_policy_active(const struct ipe_policy *p)
> +{
> +	bool rv;
> +	struct ipe_context *ctx;
> +
> +	rcu_read_lock();
> +	ctx = rcu_dereference(p->ctx);
> +	rv = !IS_ERR_OR_NULL(ctx) && rcu_access_pointer(ctx->active_policy)
> == p;
> +	rcu_read_unlock();
> +
> +	return rv;
>  }
> 
>  /**
> diff --git a/security/ipe/ctx.h b/security/ipe/ctx.h
> index a0da92da818c..fe11fb767788 100644
> --- a/security/ipe/ctx.h
> +++ b/security/ipe/ctx.h
> @@ -7,6 +7,7 @@
> 
>  #include <linux/sched.h>
>  #include <linux/types.h>
> +#include <linux/dcache.h>
>  #include <linux/refcount.h>
>  #include <linux/spinlock.h>
>  #include <linux/workqueue.h>
> @@ -20,6 +21,8 @@ struct ipe_context {
> 
>  	struct list_head policies; /* type: ipe_policy */
> 
> +	struct dentry *policy_root;
> +
>  	struct work_struct free_work;
>  };
> 
> @@ -30,5 +33,8 @@ struct ipe_context *ipe_get_ctx_rcu(struct ipe_context
> __rcu *ctx);
>  void ipe_put_ctx(struct ipe_context *ctx);
>  void ipe_add_policy(struct ipe_context *ctx, struct ipe_policy *p);
>  void ipe_remove_policy(struct ipe_policy *p);
> +int ipe_replace_policy(struct ipe_policy *old, struct ipe_policy *new);
> +int ipe_set_active_pol(const struct ipe_policy *p);
> +bool ipe_is_policy_active(const struct ipe_policy *p);
> 
>  #endif /* IPE_CONTEXT_H */
> diff --git a/security/ipe/fs.c b/security/ipe/fs.c
> new file mode 100644
> index 000000000000..10ad23f8bf92
> --- /dev/null
> +++ b/security/ipe/fs.c
> @@ -0,0 +1,170 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) Microsoft Corporation. All rights reserved.
> + */
> +#include "ipe.h"
> +#include "fs.h"
> +#include "policy.h"
> +
> +#include <linux/dcache.h>
> +#include <linux/security.h>
> +
> +static struct dentry *np __ro_after_init;
> +static struct dentry *root __ro_after_init;
> +static struct dentry *config __ro_after_init;
> +
> +/**
> + * new_policy: Write handler for the securityfs node, "ipe/new_policy"
> + * @f: Supplies a file structure representing the securityfs node.
> + * @data: Suppleis a buffer passed to the write syscall
> + * @len: Supplies the length of @data
> + * @offset: unused.
> + *
> + * Return:
> + * >0 - Success, Length of buffer written
> + * <0 - Error
> + */
> +static ssize_t new_policy(struct file *f, const char __user *data,
> +			  size_t len, loff_t *offset)
> +{
> +	int rc = 0;
> +	char *copy = NULL;
> +	struct ipe_policy *p = NULL;
> +	struct ipe_context *ctx = NULL;
> +
> +	if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
> +		return -EPERM;
> +
> +	ctx = ipe_current_ctx();
> +
> +	copy = memdup_user_nul(data, len);
> +	if (IS_ERR(copy)) {
> +		rc = PTR_ERR(copy);
> +		goto err;
> +	}
> +
> +	p = ipe_new_policy(NULL, 0, copy, len);
> +	if (IS_ERR(p)) {
> +		rc = PTR_ERR(p);
> +		goto err;
> +	}
> +
> +	rc = ipe_new_policyfs_node(ctx, p);
> +	if (rc)
> +		goto err;
> +
> +	ipe_add_policy(ctx, p);
> +err:
> +	ipe_put_policy(p);
> +	ipe_put_ctx(ctx);
> +	return (rc < 0) ? rc : len;
> +}
> +
> +/**
> + * get_config: Read handler for the securityfs node, "ipe/config"
> + * @f: Supplies a file structure representing the securityfs node.
> + * @data: Supplies a buffer passed to the read syscall
> + * @len: Supplies the length of @data
> + * @offset: unused.
> + *
> + * Return:
> + * >0 - Success, Length of buffer written
> + * <0 - Error
> + */
> +static ssize_t get_config(struct file *f, char __user *data, size_t len,
> +			  loff_t *offset)
> +{
> +	int rc = 0;
> +	char *buf = NULL;
> +	size_t buflen = 0;
> +	char tmp[30] = { 0 };
> +	struct ipe_parser *p = NULL;
> +	struct ipe_module *m = NULL;
> +
> +	for (p = __start_ipe_parsers; p < __end_ipe_parsers; ++p)
> +		buflen += snprintf(NULL, 0, "%s=%d\n", p->first_token, p-
> >version);
> +	for (m = __start_ipe_modules; m < __end_ipe_modules; ++m)
> +		buflen += snprintf(NULL, 0, "%s=%d\n", m->name, m->version);
> +
> +	++buflen;
> +	buf = kzalloc(buflen, GFP_KERNEL);
> +	if (!buf) {
> +		rc = -ENOMEM;
> +		goto out;
> +	}
> +
> +	for (p = __start_ipe_parsers; p < __end_ipe_parsers; ++p) {
> +		memset(tmp, 0x0, ARRAY_SIZE(tmp));
> +		scnprintf(tmp, ARRAY_SIZE(tmp), "%s=%d\n", p->first_token, p-
> >version);
> +		strcat(buf, tmp);
> +	}
> +
> +	for (m = __start_ipe_modules; m < __end_ipe_modules; ++m) {
> +		memset(tmp, 0x0, ARRAY_SIZE(tmp));
> +		scnprintf(tmp, ARRAY_SIZE(tmp), "%s=%d\n", m->name, m-
> >version);
> +		strcat(buf, tmp);
> +	}
> +
> +	rc = simple_read_from_buffer(data, len, offset, buf, buflen);
> +out:
> +	kfree(buf);
> +	return rc;
> +}
> +
> +static const struct file_operations cfg_fops = {
> +	.read = get_config,
> +};
> +
> +static const struct file_operations np_fops = {
> +	.write = new_policy,
> +};
> +
> +/**
> + * ipe_init_securityfs: Initialize IPE's securityfs tree at fsinit
> + *
> + * Return:
> + * !0 - Error
> + * 0 - OK
> + */
> +static int __init ipe_init_securityfs(void)
> +{
> +	int rc = 0;
> +	struct ipe_context *ctx = NULL;
> +
> +	ctx = ipe_current_ctx();

Hi Deven

the instruction above should be executed only if IPE LSM is
enabled. Otherwise, the kernel panics due to the illegal access
to the security blob of the task.

Roberto

HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
Managing Director: Li Peng, Zhong Ronghua

> +
> +	root = securityfs_create_dir("ipe", NULL);
> +	if (IS_ERR(root)) {
> +		rc = PTR_ERR(root);
> +		goto err;
> +	}
> +
> +	np = securityfs_create_file("new_policy", 0200, root, NULL, &np_fops);
> +	if (IS_ERR(np)) {
> +		rc = PTR_ERR(np);
> +		goto err;
> +	}
> +
> +	config = securityfs_create_file("config", 0400, root, NULL,
> +					&cfg_fops);
> +	if (IS_ERR(config)) {
> +		rc = PTR_ERR(config);
> +		goto err;
> +	}
> +
> +	ctx->policy_root = securityfs_create_dir("policies", root);
> +	if (IS_ERR(ctx->policy_root)) {
> +		rc = PTR_ERR(ctx->policy_root);
> +		goto err;
> +	}
> +
> +	return 0;
> +err:
> +	securityfs_remove(np);
> +	securityfs_remove(root);
> +	securityfs_remove(config);
> +	securityfs_remove(ctx->policy_root);
> +	return rc;
> +}
> +
> +fs_initcall(ipe_init_securityfs);
> diff --git a/security/ipe/fs.h b/security/ipe/fs.h
> new file mode 100644
> index 000000000000..4ab2f4e8c454
> --- /dev/null
> +++ b/security/ipe/fs.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) Microsoft Corporation. All rights reserved.
> + */
> +
> +#ifndef IPE_FS_H
> +#define IPE_FS_H
> +
> +void ipe_soft_del_policyfs(struct ipe_policy *p);
> +int ipe_new_policyfs_node(struct ipe_context *ctx, struct ipe_policy *p);
> +void ipe_del_policyfs_node(struct ipe_policy *p);
> +
> +#endif /* IPE_FS_H */
> diff --git a/security/ipe/policy.c b/security/ipe/policy.c
> index 8970f96453d6..b766824cc08f 100644
> --- a/security/ipe/policy.c
> +++ b/security/ipe/policy.c
> @@ -4,6 +4,7 @@
>   */
> 
>  #include "ipe.h"
> +#include "fs.h"
>  #include "policy.h"
>  #include "ipe_parser.h"
>  #include "modules.h"
> @@ -867,6 +868,8 @@ void ipe_put_policy(struct ipe_policy *p)
>  	if (IS_ERR_OR_NULL(p) || !refcount_dec_and_test(&p->refcount))
>  		return;
> 
> +	ipe_del_policyfs_node(p);
> +	securityfs_remove(p->policyfs);
>  	free_parsed_policy(p->parsed);
>  	if (!p->pkcs7)
>  		kfree(p->text);
> @@ -911,6 +914,44 @@ static int set_pkcs7_data(void *ctx, const void *data,
> size_t len,
>  	return 0;
>  }
> 
> +/**
> + * ipe_update_policy: parse a new policy and replace @old with it.
> + * @old: Supplies a pointer to the policy to replace
> + * @text: Supplies a pointer to the plain text policy
> + * @textlen: Supplies the length of @text
> + * @pkcs7: Supplies a pointer to a buffer containing a pkcs7 message.
> + * @pkcs7len: Supplies the length of @pkcs7len
> + *
> + * @text/@textlen is mutually exclusive with @pkcs7/@pkcs7len - see
> + * ipe_new_policy.
> + *
> + * Return:
> + * !IS_ERR - OK
> + */
> +struct ipe_policy *ipe_update_policy(struct ipe_policy *old,
> +				     const char *text, size_t textlen,
> +				     const char *pkcs7, size_t pkcs7len)
> +{
> +	int rc = 0;
> +	struct ipe_policy *new;
> +
> +	new = ipe_new_policy(text, textlen, pkcs7, pkcs7len);
> +	if (IS_ERR(new)) {
> +		rc = PTR_ERR(new);
> +		goto err;
> +	}
> +
> +	if (strcmp(new->parsed->name, old->parsed->name)) {
> +		rc = -EINVAL;
> +		goto err;
> +	}
> +
> +	rc = ipe_replace_policy(old, new);
> +err:
> +	ipe_put_policy(new);
> +	return (rc < 0) ? ERR_PTR(rc) : new;
> +}
> +
>  /**
>   * ipe_new_policy: allocate and parse an ipe_policy structure.
>   *
> diff --git a/security/ipe/policy.h b/security/ipe/policy.h
> index 2b5041c5a75a..6818f6405dd0 100644
> --- a/security/ipe/policy.h
> +++ b/security/ipe/policy.h
> @@ -88,12 +88,16 @@ struct ipe_policy {
> 
>  	refcount_t	refcount;
> 
> +	struct dentry *policyfs;
>  	struct list_head next;		/* type: ipe_policy */
>  	struct ipe_context __rcu *ctx;
>  };
> 
>  struct ipe_policy *ipe_new_policy(const char *text, size_t textlen,
>  				  const char *pkcs7, size_t pkcs7len);
> +struct ipe_policy *ipe_update_policy(struct ipe_policy *old, 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);
>  struct ipe_policy *ipe_get_policy_rcu(struct ipe_policy __rcu *p);
> diff --git a/security/ipe/policyfs.c b/security/ipe/policyfs.c
> new file mode 100644
> index 000000000000..d34c22e99225
> --- /dev/null
> +++ b/security/ipe/policyfs.c
> @@ -0,0 +1,528 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) Microsoft Corporation. All rights reserved.
> + */
> +#include "ipe.h"
> +#include "policy.h"
> +#include "fs.h"
> +
> +#include <linux/fs.h>
> +#include <linux/namei.h>
> +#include <linux/types.h>
> +#include <linux/dcache.h>
> +#include <linux/security.h>
> +
> +#define MAX_VERSION_SIZE ARRAY_SIZE("65535.65535.65535")
> +
> +/**
> + * find_policy: Follow the i_private field of a dentry, returning the address
> + *		of the resulting policy structure.
> + * @f: Securityfs object that contains a link to the dentry containing the
> + *     policy structure.
> + *
> + * Return:
> + * Always-Valid Address Pointer
> + */
> +static inline struct ipe_policy __rcu **find_policy(struct file *f)
> +{
> +	struct dentry *link;
> +
> +	link = d_inode(f->f_path.dentry)->i_private;
> +
> +	return (struct ipe_policy __rcu **)&(d_inode(link)->i_private);
> +}
> +
> +/**
> + * 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 the securityfs node,
> + *	       "ipe/policies/$name/pkcs7"
> + * @f: Supplies a file structure representing the securityfs node.
> + * @data: Suppleis a buffer passed to the write syscall
> + * @len: Supplies the length of @data
> + * @offset: unused.
> + *
> + * @data will be populated with the pkcs7 blob representing the policy
> + * on success. If the policy is unsigned (like the boot policy), this
> + * will return -ENOENT.
> + *
> + * Return:
> + * >0 - Success, Length of buffer written
> + * <0 - Error
> + */
> +static ssize_t read_pkcs7(struct file *f, char __user *data,
> +			  size_t len, loff_t *offset)
> +{
> +	int rc = 0;
> +	struct ipe_policy *p = NULL;
> +
> +	p = ipe_get_policy_rcu(*find_policy(f));
> +	if (!p)
> +		return -ENOENT;
> +
> +	if (!p->pkcs7) {
> +		rc = -ENOENT;
> +		goto out;
> +	}
> +
> +	rc = simple_read_from_buffer(data, len, offset, p->pkcs7, p->pkcs7len);
> +
> +out:
> +	ipe_put_policy(p);
> +	return rc;
> +}
> +
> +/**
> + * read_policy: Read handler for the securityfs node,
> + *		"ipe/policies/$name/policy"
> + * @f: Supplies a file structure representing the securityfs node.
> + * @data: Suppleis 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:
> + * >0 - Success, Length of buffer written
> + * <0 - Error
> + */
> +static ssize_t read_policy(struct file *f, char __user *data,
> +			   size_t len, loff_t *offset)
> +{
> +	int rc = 0;
> +	struct ipe_policy *p = NULL;
> +
> +	p = ipe_get_policy_rcu(*find_policy(f));
> +	if (!p)
> +		return -ENOENT;
> +
> +	rc = simple_read_from_buffer(data, len, offset, p->text, p->textlen);
> +
> +	ipe_put_policy(p);
> +	return rc;
> +}
> +
> +/**
> + * read_name: Read handler for the securityfs node,
> + *	      "ipe/policies/$name/name"
> + * @f: Supplies a file structure representing the securityfs node.
> + * @data: Suppleis a buffer passed to the write syscall
> + * @len: Supplies the length of @data
> + * @offset: unused.
> + *
> + * @data will be populated with the policy_name attribute on success
> + *
> + * Return:
> + * >0 - Success, Length of buffer written
> + * <0 - Error
> + */
> +static ssize_t read_name(struct file *f, char __user *data,
> +			 size_t len, loff_t *offset)
> +{
> +	int rc = 0;
> +	struct ipe_policy *p = NULL;
> +
> +	p = ipe_get_policy_rcu(*find_policy(f));
> +	if (!p)
> +		return -ENOENT;
> +
> +	rc = simple_read_from_buffer(data, len, offset, p->parsed->name,
> +				     strlen(p->parsed->name));
> +
> +	ipe_put_policy(p);
> +	return rc;
> +}
> +
> +/**
> + * read_version: Read handler for the securityfs node,
> + *		 "ipe/policies/$name/version"
> + * @f: Supplies a file structure representing the securityfs node.
> + * @data: Suppleis 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:
> + * >0 - Success, Length of buffer written
> + * <0 - Error
> + */
> +static ssize_t read_version(struct file *f, char __user *data,
> +			    size_t len, loff_t *offset)
> +{
> +	ssize_t rc = 0;
> +	size_t bufsize = 0;
> +	struct ipe_policy *p = NULL;
> +	char buffer[MAX_VERSION_SIZE] = { 0 };
> +
> +	p = ipe_get_policy_rcu(*find_policy(f));
> +	if (!p)
> +		return -ENOENT;
> +
> +	bufsize = 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, bufsize);
> +
> +	ipe_put_policy(p);
> +	return rc;
> +}
> +
> +/**
> + * setactive: Write handler for the securityfs node,
> + *	      "ipe/policies/$name/active"
> + * @f: Supplies a file structure representing the securityfs node.
> + * @data: Supplies a buffer passed to the write syscall
> + * @len: Supplies the length of @data
> + * @offset: unused.
> + *
> + * Return:
> + * >0 - Success, Length of buffer written
> + * <0 - Error
> + */
> +static ssize_t setactive(struct file *f, const char __user *data,
> +			 size_t len, loff_t *offset)
> +{
> +	int rc = 0;
> +	bool value = false;
> +	struct ipe_policy *p = NULL;
> +	struct ipe_context *ctx = NULL;
> +
> +	if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
> +		return -EPERM;
> +
> +	rc = kstrtobool_from_user(data, len, &value);
> +	if (rc)
> +		goto out;
> +
> +	if (!value) {
> +		rc = -EINVAL;
> +		goto out;
> +	}
> +
> +	p = ipe_get_policy_rcu(*find_policy(f));
> +	if (!p) {
> +		rc = -ENOENT;
> +		goto out;
> +	}
> +
> +	ctx = ipe_get_ctx_rcu(p->ctx);
> +	if (!ctx) {
> +		rc = -ENOENT;
> +		goto out;
> +	}
> +
> +	rc = ipe_set_active_pol(p);
> +
> +out:
> +	ipe_put_ctx(ctx);
> +	ipe_put_policy(p);
> +	return (rc < 0) ? rc : len;
> +}
> +
> +/**
> + * getactive: Read handler for the securityfs node,
> + *	      "ipe/policies/$name/active"
> + * @f: Supplies a file structure representing the securityfs node.
> + * @data: Suppleis 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:
> + * >0 - Success, Length of buffer written
> + * <0 - Error
> + */
> +static ssize_t getactive(struct file *f, char __user *data,
> +			 size_t len, loff_t *offset)
> +{
> +	int rc = 0;
> +	const char *str;
> +	struct ipe_policy *p = NULL;
> +
> +	p = ipe_get_policy_rcu(*find_policy(f));
> +	if (!p) {
> +		rc = -ENOENT;
> +		goto out;
> +	}
> +
> +	str = ipe_is_policy_active(p) ? "1" : "0";
> +	rc = simple_read_from_buffer(data, len, offset, str, 2);
> +
> +out:
> +	ipe_put_policy(p);
> +	return rc;
> +}
> +
> +/**
> + * update_policy: Write handler for the securityfs node,
> + *		  "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.
> + *
> + * On success this updates the policy represented by $name,
> + * in-place.
> + *
> + * Return:
> + * >0 - Success, Length of buffer written
> + * <0 - Error
> + */
> +static ssize_t update_policy(struct file *f, const char __user *data,
> +			     size_t len, loff_t *offset)
> +{
> +	int rc = 0;
> +	char *copy = NULL;
> +	struct ipe_policy *new = NULL;
> +	struct ipe_policy *old = NULL;
> +	struct ipe_context *ctx = NULL;
> +	struct ipe_policy __rcu **addr = NULL;
> +
> +	if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
> +		return -EPERM;
> +
> +	ctx = ipe_current_ctx();
> +	if (!ctx)
> +		return -ENOENT;
> +
> +	addr = find_policy(f);
> +	old = ipe_get_policy_rcu(*addr);
> +	if (!old) {
> +		rc = -ENOENT;
> +		goto err;
> +	}
> +
> +	copy = memdup_user(data, len);
> +	if (IS_ERR(copy)) {
> +		rc = PTR_ERR(copy);
> +		goto err;
> +	}
> +
> +	new = ipe_update_policy(old, NULL, 0, copy, len);
> +	if (IS_ERR(new)) {
> +		rc = PTR_ERR(new);
> +		goto err;
> +	}
> +
> +	spin_lock(&ctx->lock);
> +	rcu_assign_pointer(*addr, new);
> +	spin_unlock(&ctx->lock);
> +	synchronize_rcu();
> +
> +	swap(new->policyfs, old->policyfs);
> +
> +	kfree(copy);
> +	ipe_put_ctx(ctx);
> +	ipe_put_policy(old);
> +	return len;
> +err:
> +	kfree(copy);
> +	ipe_put_ctx(ctx);
> +	ipe_put_policy(new);
> +	ipe_put_policy(old);
> +	return rc;
> +}
> +
> +/**
> + * delete_policy: write handler for securityfs dir, "ipe/policies/$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:
> + * >0 - Success, Length of buffer written
> + * <0 - Error
> + */
> +static ssize_t delete_policy(struct file *f, const char __user *data,
> +			     size_t len, loff_t *offset)
> +{
> +	int rc = 0;
> +	bool value = false;
> +	struct ipe_policy *p = NULL;
> +	struct ipe_context *ctx = NULL;
> +
> +	if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
> +		return -EPERM;
> +
> +	rc = kstrtobool_from_user(data, len, &value);
> +	if (rc)
> +		goto out;
> +
> +	if (!value) {
> +		rc = -EINVAL;
> +		goto out;
> +	}
> +
> +	p = ipe_get_policy_rcu(*find_policy(f));
> +	if (!p) {
> +		rc = -ENOENT;
> +		goto out;
> +	}
> +
> +	if (ipe_is_policy_active(p)) {
> +		rc = -EPERM;
> +		goto out;
> +	}
> +
> +	ctx = ipe_get_ctx_rcu(p->ctx);
> +	if (!ctx) {
> +		rc = -ENOENT;
> +		goto out;
> +	}
> +
> +	ipe_remove_policy(p);
> +out:
> +	ipe_put_ctx(ctx);
> +	ipe_put_policy(p);
> +	return (rc < 0) ? rc : 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 },
> +};
> +
> +/**
> + * soft_del_policyfs - soft delete the policyfs tree, preventing new
> + *		       accesses to the interfaces for this policy.
> + * @p - Policy to soft delete the tree for.
> + */
> +static void soft_del_policyfs(struct ipe_policy *p)
> +{
> +	struct inode *ino = NULL;
> +	struct ipe_policy __rcu **addr = NULL;
> +
> +	ino = d_inode(p->policyfs);
> +	addr = (struct ipe_policy __rcu **)&ino->i_private;
> +
> +	inode_lock(ino);
> +	rcu_assign_pointer(*addr, NULL);
> +	inode_unlock(ino);
> +	synchronize_rcu();
> +}
> +
> +/**
> + * 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)
> +{
> +	size_t i = 0;
> +	struct dentry *d = NULL;
> +	const struct ipefs_file *f = NULL;
> +
> +	if (IS_ERR_OR_NULL(p->policyfs))
> +		return;
> +
> +	soft_del_policyfs(p);
> +
> +	for (i = 0; i < ARRAY_SIZE(policy_subdir); ++i) {
> +		f = &policy_subdir[i];
> +
> +		d = lookup_positive_unlocked(f->name, p->policyfs,
> +					     strlen(f->name));
> +		if (IS_ERR(d))
> +			continue;
> +
> +		securityfs_remove(d);
> +		dput(d);
> +	}
> +
> +	securityfs_remove(p->policyfs);
> +}
> +
> +/**
> + * ipe_new_policyfs_node: Create a securityfs entry for @p
> + * @ctx: Supplies a pointer to a context structure that contains the root of
> + *	 the policy tree.
> + * @p: Supplies a pointer to the policy to create a securityfs entry for.
> + *
> + * Return:
> + * 0 - OK
> + * !0 - Error
> + */
> +int ipe_new_policyfs_node(struct ipe_context *ctx, struct ipe_policy *p)
> +{
> +	int rc = 0;
> +	size_t i = 0;
> +	struct dentry *d = NULL;
> +	struct ipe_policy **addr = NULL;
> +	const struct ipefs_file *f = NULL;
> +
> +	p->policyfs = securityfs_create_dir(p->parsed->name, ctx->policy_root);
> +	if (IS_ERR(p->policyfs)) {
> +		rc = PTR_ERR(p->policyfs);
> +		goto err;
> +	}
> +
> +	addr = (struct ipe_policy **)&(d_inode(p->policyfs)->i_private);
> +	*addr = p;
> +
> +	for (i = 0; i < ARRAY_SIZE(policy_subdir); ++i) {
> +		f = &policy_subdir[i];
> +
> +		d = securityfs_create_file(f->name, f->access, p->policyfs, p-
> >policyfs,
> +					   f->fops);
> +		if (IS_ERR(d)) {
> +			rc = PTR_ERR(d);
> +			goto err;
> +		}
> +	}
> +
> +	return 0;
> +err:
> +	ipe_del_policyfs_node(p);
> +	return rc;
> +}
> --
> 2.33.0