@@ -8,6 +8,7 @@ menuconfig SECURITY_IPE
depends on SECURITY && SECURITYFS && AUDIT && AUDITSYSCALL
select PKCS7_MESSAGE_PARSER
select SYSTEM_DATA_VERIFICATION
+ select IPE_PROP_DM_VERITY if DM_VERITY && DM_VERITY_VERIFY_ROOTHASH_SIG
help
This option enables the Integrity Policy Enforcement LSM
allowing users to define a policy to enforce a trust-based access
@@ -15,3 +16,20 @@ menuconfig SECURITY_IPE
admins to reconfigure trust requirements on the fly.
If unsure, answer N.
+
+if SECURITY_IPE
+menu "IPE Trust Providers"
+
+config IPE_PROP_DM_VERITY
+ bool "Enable support for dm-verity volumes"
+ depends on DM_VERITY && DM_VERITY_VERIFY_ROOTHASH_SIG
+ help
+ This option enables the properties 'dmverity_signature' and
+ 'dmverity_roothash' in IPE policy. These properties evaluates
+ to TRUE when a file is evaluated against a dm-verity volume
+ that was mounted with a signed root-hash or the volume's
+ root hash matches the supplied value in the policy.
+
+endmenu
+
+endif
@@ -6,6 +6,7 @@
#
obj-$(CONFIG_SECURITY_IPE) += \
+ digest.o \
eval.o \
fs.o \
hooks.o \
@@ -13,6 +13,7 @@
#include "hooks.h"
#include "policy.h"
#include "audit.h"
+#include "digest.h"
#define ACTSTR(x) ((x) == __IPE_ACTION_ALLOW ? "ALLOW" : "DENY")
@@ -40,8 +41,29 @@ static const char *const audit_op_names[__IPE_OP_MAX] = {
static const char *const audit_prop_names[__IPE_PROP_MAX] = {
"boot_verified=FALSE",
"boot_verified=TRUE",
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+ "dmverity_roothash=",
+ "dmverity_signature=FALSE",
+ "dmverity_signature=TRUE",
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
};
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+/**
+ * audit_dmv_roothash - audit a roothash of a dmverity volume.
+ * @ab: Supplies a pointer to the audit_buffer to append to.
+ * @r: Supplies a pointer to the digest structure.
+ */
+static void audit_dmv_roothash(struct audit_buffer *ab, const void *rh)
+{
+ ipe_digest_audit(ab, rh);
+}
+#else
+static void audit_dmv_roothash(struct audit_buffer *ab, const void *rh)
+{
+}
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
+
/**
* audit_rule - audit an IPE policy rule approximation.
* @ab: Supplies a pointer to the audit_buffer to append to.
@@ -55,6 +77,9 @@ static void audit_rule(struct audit_buffer *ab, const struct ipe_rule *r)
list_for_each_entry(ptr, &r->props, next) {
audit_log_format(ab, "%s", audit_prop_names[ptr->type]);
+ if (ptr->type == __IPE_PROP_DMV_ROOTHASH)
+ audit_dmv_roothash(ab, ptr->value);
+
audit_log_format(ab, " ");
}
new file mode 100644
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+
+#include "digest.h"
+
+/**
+ * ipe_digest_parse - parse a digest in IPE's policy.
+ * @valstr: Supplies the string parsed from the policy.
+ * @value: Supplies a pointer to be populated with the result.
+ *
+ * Digests in IPE are defined in a standard way:
+ * <alg_name>:<hex>
+ *
+ * Use this function to create a property to parse the digest
+ * consistently. The parsed digest will be saved in @value in IPE's
+ * policy.
+ *
+ * Return:
+ * * 0 - OK
+ * * !0 - Error
+ */
+int ipe_digest_parse(const char *valstr, void **value)
+{
+ char *sep, *raw_digest;
+ size_t raw_digest_len;
+ int rc = 0;
+ u8 *digest = NULL;
+ struct digest_info *info = NULL;
+
+ info = kzalloc(sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+
+ sep = strchr(valstr, ':');
+ if (!sep) {
+ rc = -EBADMSG;
+ goto err;
+ }
+
+ info->alg = kstrndup(valstr, sep - valstr, GFP_KERNEL);
+ if (!info->alg) {
+ rc = -ENOMEM;
+ goto err;
+ }
+
+ raw_digest = sep + 1;
+ raw_digest_len = strlen(raw_digest);
+ info->raw_digest = kstrndup(raw_digest, raw_digest_len, GFP_KERNEL);
+ if (!info->raw_digest) {
+ rc = -ENOMEM;
+ goto err_free_alg;
+ }
+
+ info->digest_len = (raw_digest_len + 1) / 2;
+ digest = kzalloc(info->digest_len, GFP_KERNEL);
+ if (!digest) {
+ rc = -ENOMEM;
+ goto err_free_raw;
+ }
+
+ rc = hex2bin(digest, raw_digest, info->digest_len);
+ if (rc < 0) {
+ rc = -EINVAL;
+ goto err_free_raw;
+ }
+
+ info->digest = digest;
+ *value = info;
+ return 0;
+
+err_free_raw:
+ kfree(info->raw_digest);
+err_free_alg:
+ kfree(info->alg);
+err:
+ kfree(digest);
+ kfree(info);
+ return rc;
+}
+
+/**
+ * ipe_digest_eval - evaluate an IPE digest against another digest.
+ * @expect: Supplies the policy-provided digest value.
+ * @digest: Supplies the digest to compare against the policy digest value.
+ * @digest_len: The length of @digest.
+ * @alg: Supplies the name of the algorithm used to calculated @digest.
+ *
+ * Return:
+ * * true - digests match
+ * * false - digests do not match
+ */
+bool ipe_digest_eval(const void *expect, const u8 *digest, size_t digest_len,
+ const char *alg)
+{
+ const struct digest_info *info = (struct digest_info *)expect;
+
+ return (digest_len == info->digest_len) && !strcmp(alg, info->alg) &&
+ (!memcmp(info->digest, digest, info->digest_len));
+}
+
+/**
+ * ipe_digest_free - free an IPE digest.
+ * @value: Supplies a pointer the policy-provided digest value to free.
+ */
+void ipe_digest_free(void **value)
+{
+ struct digest_info *info = (struct digest_info *)(*value);
+
+ if (IS_ERR_OR_NULL(info))
+ return;
+
+ kfree(info->alg);
+ kfree(info->raw_digest);
+ kfree(info->digest);
+ kfree(info);
+}
+
+/**
+ * ipe_digest_audit - audit a digest that was sourced from IPE's policy.
+ * @ab: Supplies the audit_buffer to append the formatted result.
+ * @val: Supplies a pointer to source the audit record from.
+ *
+ * Digests in IPE are defined in a standard way:
+ * <alg_name>:<hex>
+ *
+ * Use this function to create a property to audit the digest
+ * consistently.
+ *
+ * Return:
+ * 0 - OK
+ * !0 - Error
+ */
+void ipe_digest_audit(struct audit_buffer *ab, const void *val)
+{
+ const struct digest_info *info = (struct digest_info *)val;
+
+ audit_log_untrustedstring(ab, info->alg);
+ audit_log_format(ab, ":");
+ audit_log_untrustedstring(ab, info->raw_digest);
+}
new file mode 100644
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+
+#ifndef _IPE_DIGEST_H
+#define _IPE_DIGEST_H
+
+#include "policy.h"
+#include <linux/types.h>
+#include <linux/audit.h>
+
+struct digest_info {
+ const char *alg;
+ const char *raw_digest;
+ const u8 *digest;
+ size_t digest_len;
+};
+
+int ipe_digest_parse(const char *valstr, void **value);
+void ipe_digest_free(void **value);
+void ipe_digest_audit(struct audit_buffer *ab, const void *val);
+bool ipe_digest_eval(const void *expect, const u8 *digest, size_t digest_len,
+ const char *alg);
+
+#endif /* _IPE_DIGEST_H */
@@ -17,10 +17,12 @@
#include "hooks.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)
static const struct super_block *pinned_sb;
static DEFINE_SPINLOCK(pin_lock);
@@ -60,6 +62,23 @@ static bool from_pinned(const struct super_block *sb)
return rv;
}
+#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 populdated.
+ * @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 */
+
/**
* build_eval_ctx - Build an evaluation context.
* @ctx: Supplies a pointer to the context to be populdated.
@@ -70,15 +89,89 @@ void build_eval_ctx(struct ipe_eval_ctx *ctx,
const struct file *file,
enum ipe_op_type op)
{
+ struct inode *ino = NULL;
+
if (op == __IPE_OP_EXEC && file)
pin_sb(FILE_SUPERBLOCK(file));
ctx->file = file;
ctx->op = op;
- if (file)
+ if (file) {
ctx->from_init_sb = from_pinned(FILE_SUPERBLOCK(file));
+ ino = d_real_inode(file->f_path.dentry);
+ build_ipe_bdev_ctx(ctx, ino);
+ }
+}
+
+#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 &&
+ ipe_digest_eval(p->value,
+ ctx->ipe_bdev->digest,
+ ctx->ipe_bdev->digest_len,
+ ctx->ipe_bdev->digest_algo);
+}
+
+/**
+ * evaluate_dmv_sig_false: Analyze @ctx against a dmv sig false 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_sig_false(const struct ipe_eval_ctx *const ctx,
+ struct ipe_prop *p)
+{
+ return !ctx->ipe_bdev || (!ctx->ipe_bdev->dm_verity_signed);
+}
+
+/**
+ * evaluate_dmv_sig_true: Analyze @ctx against a dmv sig true 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_sig_true(const struct ipe_eval_ctx *const ctx,
+ struct ipe_prop *p)
+{
+ return ctx->ipe_bdev && (!!ctx->ipe_bdev->dm_verity_signed);
+}
+#else
+static bool evaluate_dmv_roothash(const struct ipe_eval_ctx *const ctx,
+ struct ipe_prop *p)
+{
+ return false;
+}
+
+static bool evaluate_dmv_sig_false(const struct ipe_eval_ctx *const ctx,
+ struct ipe_prop *p)
+{
+ return false;
+}
+
+static bool evaluate_dmv_sig_true(const struct ipe_eval_ctx *const ctx,
+ struct ipe_prop *p)
+{
+ return false;
}
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
/**
* evaluate_property - Analyze @ctx against a property.
@@ -97,6 +190,12 @@ static bool evaluate_property(const struct ipe_eval_ctx *const ctx,
return !ctx->from_init_sb;
case __IPE_PROP_BOOT_VERIFIED_TRUE:
return ctx->from_init_sb;
+ case __IPE_PROP_DMV_ROOTHASH:
+ return evaluate_dmv_roothash(ctx, p);
+ case __IPE_PROP_DMV_SIG_FALSE:
+ return evaluate_dmv_sig_false(ctx, p);
+ case __IPE_PROP_DMV_SIG_TRUE:
+ return evaluate_dmv_sig_true(ctx, p);
default:
return false;
}
@@ -16,11 +16,24 @@ extern struct ipe_policy __rcu *ipe_active_policy;
extern bool success_audit;
extern bool enforce;
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+struct ipe_bdev {
+ bool dm_verity_signed;
+
+ const u8 *digest;
+ size_t digest_len;
+ const char *digest_algo;
+};
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
+
struct ipe_eval_ctx {
enum ipe_op_type op;
const struct file *file;
bool from_init_sb;
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+ const struct ipe_bdev *ipe_bdev;
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
};
enum ipe_match {
@@ -7,6 +7,9 @@
#include <linux/types.h>
#include <linux/binfmts.h>
#include <linux/mman.h>
+#include <linux/blk_types.h>
+#include <linux/dm-verity.h>
+#include <crypto/hash_info.h>
#include "ipe.h"
#include "hooks.h"
@@ -192,3 +195,51 @@ void ipe_sb_free_security(struct super_block *mnt_sb)
{
ipe_invalidate_pinned_sb(mnt_sb);
}
+
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+/**
+ * ipe_bdev_free_security - free IPE's LSM blob of block_devices.
+ * @bdev: Supplies a pointer to a block_device that contains the structure
+ * to free.
+ */
+void ipe_bdev_free_security(struct block_device *bdev)
+{
+ struct ipe_bdev *blob = ipe_bdev(bdev);
+
+ kfree(blob->digest);
+ kfree(blob->digest_algo);
+}
+
+/**
+ * ipe_bdev_setsecurity - save data from a bdev to IPE's LSM blob.
+ * @bdev: Supplies a pointer to a block_device that contains the LSM blob.
+ * @key: Supplies the string key that uniquely identifies the value.
+ * @value: Supplies the value to store.
+ * @len: The length of @value.
+ */
+int ipe_bdev_setsecurity(struct block_device *bdev, const char *key,
+ const void *value, size_t len)
+{
+ struct ipe_bdev *blob = ipe_bdev(bdev);
+
+ if (!strcmp(key, DM_VERITY_ROOTHASH_SEC_NAME)) {
+ const struct dm_verity_digest *digest = value;
+
+ blob->digest = kmemdup(digest->digest, digest->digest_len, GFP_KERNEL);
+ if (!blob->digest)
+ return -ENOMEM;
+
+ blob->digest_algo = kstrdup_const(digest->algo, GFP_KERNEL);
+ if (!blob->digest_algo)
+ return -ENOMEM;
+
+ blob->digest_len = digest->digest_len;
+ return 0;
+ } else if (!strcmp(key, DM_VERITY_SIGNATURE_SEC_NAME)) {
+ blob->dm_verity_signed = true;
+ return 0;
+ }
+
+ return -EOPNOTSUPP;
+}
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
@@ -8,6 +8,7 @@
#include <linux/fs.h>
#include <linux/binfmts.h>
#include <linux/security.h>
+#include <linux/device-mapper.h>
int ipe_bprm_check_security(struct linux_binprm *bprm);
@@ -24,4 +25,11 @@ int ipe_kernel_load_data(enum kernel_load_data_id id, bool contents);
void ipe_sb_free_security(struct super_block *mnt_sb);
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+void ipe_bdev_free_security(struct block_device *bdev);
+
+int ipe_bdev_setsecurity(struct block_device *bdev, const char *key,
+ const void *value, size_t len);
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
+
#endif /* _IPE_HOOKS_H */
@@ -5,12 +5,23 @@
#include "ipe.h"
#include "hooks.h"
+#include "eval.h"
bool ipe_enabled;
static struct lsm_blob_sizes ipe_blobs __ro_after_init = {
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+ .lbs_bdev = sizeof(struct ipe_bdev),
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
};
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+struct ipe_bdev *ipe_bdev(struct block_device *b)
+{
+ return b->security + ipe_blobs.lbs_bdev;
+}
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
+
static struct security_hook_list ipe_hooks[] __ro_after_init = {
LSM_HOOK_INIT(bprm_check_security, ipe_bprm_check_security),
LSM_HOOK_INIT(mmap_file, ipe_mmap_file),
@@ -18,6 +29,10 @@ static struct security_hook_list ipe_hooks[] __ro_after_init = {
LSM_HOOK_INIT(kernel_read_file, ipe_kernel_read_file),
LSM_HOOK_INIT(kernel_load_data, ipe_kernel_load_data),
LSM_HOOK_INIT(sb_free_security, ipe_sb_free_security),
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+ LSM_HOOK_INIT(bdev_free_security, ipe_bdev_free_security),
+ LSM_HOOK_INIT(bdev_setsecurity, ipe_bdev_setsecurity),
+#endif
};
/**
@@ -15,4 +15,8 @@
extern bool ipe_enabled;
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+struct ipe_bdev *ipe_bdev(struct block_device *b);
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
+
#endif /* _IPE_H */
@@ -33,6 +33,9 @@ enum ipe_action_type {
enum ipe_prop_type {
__IPE_PROP_BOOT_VERIFIED_FALSE,
__IPE_PROP_BOOT_VERIFIED_TRUE,
+ __IPE_PROP_DMV_ROOTHASH,
+ __IPE_PROP_DMV_SIG_FALSE,
+ __IPE_PROP_DMV_SIG_TRUE,
__IPE_PROP_MAX
};
@@ -8,6 +8,7 @@
#include "policy.h"
#include "policy_parser.h"
+#include "digest.h"
#define START_COMMENT '#'
@@ -216,6 +217,7 @@ static void free_rule(struct ipe_rule *r)
list_for_each_entry_safe(p, t, &r->props, next) {
list_del(&p->next);
+ ipe_digest_free(&p->value);
kfree(p);
}
@@ -268,6 +270,11 @@ static enum ipe_action_type parse_action(char *t)
static const match_table_t property_tokens = {
{__IPE_PROP_BOOT_VERIFIED_FALSE, "boot_verified=FALSE"},
{__IPE_PROP_BOOT_VERIFIED_TRUE, "boot_verified=TRUE"},
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+ {__IPE_PROP_DMV_ROOTHASH, "dmverity_roothash=%s"},
+ {__IPE_PROP_DMV_SIG_FALSE, "dmverity_signature=FALSE"},
+ {__IPE_PROP_DMV_SIG_TRUE, "dmverity_signature=TRUE"},
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
{__IPE_PROP_INVALID, NULL}
};
@@ -287,6 +294,7 @@ static int parse_property(char *t, struct ipe_rule *r)
struct ipe_prop *p = NULL;
int rc = 0;
int token;
+ char *dup = NULL;
p = kzalloc(sizeof(*p), GFP_KERNEL);
if (!p)
@@ -295,8 +303,20 @@ static int parse_property(char *t, struct ipe_rule *r)
token = match_token(t, property_tokens, args);
switch (token) {
+ case __IPE_PROP_DMV_ROOTHASH:
+ dup = match_strdup(&args[0]);
+ if (!dup) {
+ rc = -ENOMEM;
+ goto err;
+ }
+ rc = ipe_digest_parse(dup, &p->value);
+ if (rc)
+ goto err;
+ fallthrough;
case __IPE_PROP_BOOT_VERIFIED_FALSE:
case __IPE_PROP_BOOT_VERIFIED_TRUE:
+ case __IPE_PROP_DMV_SIG_FALSE:
+ case __IPE_PROP_DMV_SIG_TRUE:
p->type = token;
break;
case __IPE_PROP_INVALID:
@@ -309,6 +329,7 @@ static int parse_property(char *t, struct ipe_rule *r)
list_add_tail(&p->next, &r->props);
out:
+ kfree(dup);
return rc;
err:
kfree(p);