[RFC,v11,05/19] ipe: introduce 'boot_verified' as a trust provider

Message ID	1696457386-3010-6-git-send-email-wufan@linux.microsoft.com (mailing list archive)
State	Not Applicable
Headers	show Return-Path: <linux-fscrypt-owner@vger.kernel.org> From: Fan Wu <wufan@linux.microsoft.com> To: corbet@lwn.net, zohar@linux.ibm.com, jmorris@namei.org, serge@hallyn.com, tytso@mit.edu, ebiggers@kernel.org, axboe@kernel.dk, agk@redhat.com, snitzer@kernel.org, eparis@redhat.com, paul@paul-moore.com Cc: linux-doc@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fscrypt@vger.kernel.org, linux-block@vger.kernel.org, dm-devel@redhat.com, audit@vger.kernel.org, roberto.sassu@huawei.com, linux-kernel@vger.kernel.org, Deven Bowers <deven.desai@linux.microsoft.com>, Fan Wu <wufan@linux.microsoft.com> Subject: [RFC PATCH v11 05/19] ipe: introduce 'boot_verified' as a trust provider Date: Wed, 4 Oct 2023 15:09:32 -0700 Message-Id: <1696457386-3010-6-git-send-email-wufan@linux.microsoft.com> In-Reply-To: <1696457386-3010-1-git-send-email-wufan@linux.microsoft.com> References: <1696457386-3010-1-git-send-email-wufan@linux.microsoft.com> Precedence: bulk
Series	Integrity Policy Enforcement LSM (IPE) \| expand [RFC,v11,00/19] Integrity Policy Enforcement LSM (IPE) [RFC,v11,01/19] security: add ipe lsm [RFC,v11,02/19] ipe: add policy parser [RFC,v11,03/19] ipe: add evaluation loop [RFC,v11,04/19] ipe: add LSM hooks on execution and kernel read [RFC,v11,05/19] ipe: introduce 'boot_verified' as a trust provider [RFC,v11,06/19] security: add new securityfs delete function [RFC,v11,07/19] ipe: add userspace interface [RFC,v11,08/19] uapi\|audit\|ipe: add ipe auditing support [RFC,v11,09/19] ipe: add permissive toggle [RFC,v11,10/19] block\|security: add LSM blob to block_device [RFC,v11,11/19] dm verity: set DM_TARGET_SINGLETON feature flag [RFC,v11,12/19] dm: add finalize hook to target_type [RFC,v11,13/19] dm verity: consume root hash digest and signature data via LSM hook [RFC,v11,14/19] ipe: add support for dm-verity as a trust provider [RFC,v11,15/19] fsverity: consume builtin signature via LSM hook [RFC,v11,16/19] ipe: enable support for fs-verity as a trust provider [RFC,v11,17/19] scripts: add boot policy generation program [RFC,v11,18/19] ipe: kunit test for parser [RFC,v11,19/19] documentation: add ipe documentation

diff --git a/security/ipe/eval.c b/security/ipe/eval.c index 8a8bcc5c7d7f..bdac4abc0ddb 100644 --- a/security/ipe/eval.c +++ b/security/ipe/eval.c @@ -9,6 +9,7 @@ #include <linux/file.h> #include <linux/sched.h> #include <linux/rcupdate.h> +#include <linux/spinlock.h> #include "ipe.h" #include "eval.h" @@ -16,6 +17,44 @@ struct ipe_policy __rcu *ipe_active_policy; +static const struct super_block *pinned_sb; +static DEFINE_SPINLOCK(pin_lock); +#define FILE_SUPERBLOCK(f) ((f)->f_path.mnt->mnt_sb) + +/** + * pin_sb - Pin the underlying superblock of @f, marking it as trusted. + * @sb: Supplies a super_block structure to be pinned. + */ +static void pin_sb(const struct super_block *sb) +{ + if (!sb) + return; + spin_lock(&pin_lock); + if (!pinned_sb) + pinned_sb = sb; + spin_unlock(&pin_lock); +} + +/** + * from_pinned - Determine whether @sb is the pinned super_block. + * @sb: Supplies a super_block to check against the pinned super_block. + * + * Return: + * * true - @sb is the pinned super_block + * * false - @sb is not the pinned super_block + */ +static bool from_pinned(const struct super_block *sb) +{ + bool rv; + + if (!sb) + return false; + spin_lock(&pin_lock); + rv = !IS_ERR_OR_NULL(pinned_sb) && pinned_sb == sb; + spin_unlock(&pin_lock); + return rv; +} + /** * build_eval_ctx - Build an evaluation context. * @ctx: Supplies a pointer to the context to be populdated. @@ -26,8 +65,14 @@ void build_eval_ctx(struct ipe_eval_ctx *ctx, const struct file *file, enum ipe_op_type op) { + if (op == IPE_OP_EXEC && file) + pin_sb(FILE_SUPERBLOCK(file)); + ctx->file = file; ctx->op = op; + + if (file) + ctx->from_init_sb = from_pinned(FILE_SUPERBLOCK(file)); } /** @@ -42,7 +87,14 @@ void build_eval_ctx(struct ipe_eval_ctx *ctx, static bool evaluate_property(const struct ipe_eval_ctx *const ctx, struct ipe_prop *p) { - return false; + switch (p->type) { + case IPE_PROP_BOOT_VERIFIED_FALSE: + return !ctx->from_init_sb; + case IPE_PROP_BOOT_VERIFIED_TRUE: + return ctx->from_init_sb; + default: + return false; + } } /** @@ -108,3 +160,21 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) return 0; } + +/** + * ipe_invalidate_pinned_sb - invalidate the ipe pinned super_block. + * @mnt_sb: super_block to check against the pinned super_block. + * + * This function is called a super_block like the initramfs's is freed, + * if the super_block is currently pinned by ipe it will be invalided, + * so ipe won't consider the block device is boot verified afterward. + */ +void ipe_invalidate_pinned_sb(const struct super_block *mnt_sb) +{ + spin_lock(&pin_lock); + + if (mnt_sb == pinned_sb) + pinned_sb = ERR_PTR(-EIO); + + spin_unlock(&pin_lock); +} diff --git a/security/ipe/eval.h b/security/ipe/eval.h index cfdf3c8dfe8a..9769da42c65f 100644 --- a/security/ipe/eval.h +++ b/security/ipe/eval.h @@ -19,9 +19,11 @@ struct ipe_eval_ctx { enum ipe_op_type op; const struct file *file; + bool from_init_sb; }; void build_eval_ctx(struct ipe_eval_ctx *ctx, const struct file *file, enum ipe_op_type op); int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx); +void ipe_invalidate_pinned_sb(const struct super_block *mnt_sb); #endif /* _IPE_EVAL_H */ diff --git a/security/ipe/hooks.c b/security/ipe/hooks.c index 6164a9b53361..e9386762a597 100644 --- a/security/ipe/hooks.c +++ b/security/ipe/hooks.c @@ -181,3 +181,15 @@ int ipe_kernel_load_data(enum kernel_load_data_id id, bool contents) build_eval_ctx(&ctx, NULL, op); return ipe_evaluate_event(&ctx); } + +/** + * ipe_sb_free_security - ipe security hook function for super_block. + * @mnt_sb: Supplies a pointer to a super_block is about to be freed. + * + * IPE does not have any structures with mnt_sb, but uses this hook to + * invalidate a pinned super_block. + */ +void ipe_sb_free_security(struct super_block *mnt_sb) +{ + ipe_invalidate_pinned_sb(mnt_sb); +} diff --git a/security/ipe/hooks.h b/security/ipe/hooks.h index 23205452f758..ac0cdfd9877f 100644 --- a/security/ipe/hooks.h +++ b/security/ipe/hooks.h @@ -22,4 +22,6 @@ int ipe_kernel_read_file(struct file *file, enum kernel_read_file_id id, int ipe_kernel_load_data(enum kernel_load_data_id id, bool contents); +void ipe_sb_free_security(struct super_block *mnt_sb); + #endif /* _IPE_HOOKS_H */ diff --git a/security/ipe/ipe.c b/security/ipe/ipe.c index 77c950459810..06da94a58aba 100644 --- a/security/ipe/ipe.c +++ b/security/ipe/ipe.c @@ -15,6 +15,7 @@ static struct security_hook_list ipe_hooks[] __ro_after_init = { LSM_HOOK_INIT(file_mprotect, ipe_file_mprotect), 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), }; /** diff --git a/security/ipe/policy.h b/security/ipe/policy.h index 77aa91f2b953..45704465dc01 100644 --- a/security/ipe/policy.h +++ b/security/ipe/policy.h @@ -30,6 +30,8 @@ enum ipe_action_type { #define IPE_ACTION_INVALID __IPE_ACTION_MAX enum ipe_prop_type { + IPE_PROP_BOOT_VERIFIED_FALSE, + IPE_PROP_BOOT_VERIFIED_TRUE, __IPE_PROP_MAX }; diff --git a/security/ipe/policy_parser.c b/security/ipe/policy_parser.c index c09458bd348d..ee7646de72ed 100644 --- a/security/ipe/policy_parser.c +++ b/security/ipe/policy_parser.c @@ -265,6 +265,12 @@ static enum ipe_action_type parse_action(char *t) return match_token(t, action_tokens, args); } +static const match_table_t property_tokens = { + {IPE_PROP_BOOT_VERIFIED_FALSE, "boot_verified=FALSE"}, + {IPE_PROP_BOOT_VERIFIED_TRUE, "boot_verified=TRUE"}, + {IPE_PROP_INVALID, NULL} +}; + /** * parse_property - Parse the property type given a token string. * @t: Supplies the token string to be parsed. @@ -277,7 +283,34 @@ static enum ipe_action_type parse_action(char *t) */ static int parse_property(char *t, struct ipe_rule *r) { - return -EBADMSG; + substring_t args[MAX_OPT_ARGS]; + struct ipe_prop *p = NULL; + int rc = 0; + int token; + + p = kzalloc(sizeof(*p), GFP_KERNEL); + if (!p) + return -ENOMEM; + + token = match_token(t, property_tokens, args); + + switch (token) { + case IPE_PROP_BOOT_VERIFIED_FALSE: + case IPE_PROP_BOOT_VERIFIED_TRUE: + p->type = token; + break; + default: + rc = -EBADMSG; + break; + } + if (rc) + goto err; + list_add_tail(&p->next, &r->props); + + return rc; +err: + kfree(p); + return rc; } /**

[RFC,v11,05/19] ipe: introduce 'boot_verified' as a trust provider

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