From patchwork Sat Mar 16 03:35:40 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fan Wu X-Patchwork-Id: 13594253 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id AA95D63D0; Sat, 16 Mar 2024 03:35:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710560159; cv=none; b=Owri0fDq0XIZ1UxOMMcd0VrpIcvTh89nAvoUD/l8JoVybDuP3HHVSGwIwGIIolYSl/NytD3J4N/IVw5uICOHILDNmmXWr5oKr6/MV6lHU4oTpEDngk4oRsEMUpDL38ha2tRbhsdWFSWm6iTKoiSLapgr8UMh2cP0ndawyuxRiHw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710560159; c=relaxed/simple; bh=6t9BEvWaMcIaCVEeeGnUIPJ/mMudkG4bOr8epzDYiq4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References; b=VEIaHB77URh5Zh25P+rIl73DUq6YaOb3BldzlrRvWTwIhOBFzi++iwQTJ/q0r8Azp9H4o90EFUww1ooyStLoNNXbDeNUP4vJcd1hptAT96HpG2csnFuXNRGBA40zD1gxMR2l4uCzv5kIiIw1ZY/F13xf9Rz/9Z610GRCPLgc8fs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=kj14USb0; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="kj14USb0" Received: by linux.microsoft.com (Postfix, from userid 1052) id BED1220B74D3; Fri, 15 Mar 2024 20:35:53 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com BED1220B74D3 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1710560153; bh=j1PJ7f2wNKceGww3zk5/9GSWDNHp/DvwLwbB4Saq6ck=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kj14USb0VgJPgjVyOVbWyMD9AY/fyOB8nEfr4zh1gT1b4SSh2j9hvJxIPXDXwdIw3 NxxidVJX9VoKlVkevd32I0EjCchCta4I73c3AJcf67ZHtmX1WzIQAF/KfkoigoFZLq N2XaFJHD2d2hXi/tcOArkRPEtw95ULqf+z1R/31o= From: Fan Wu 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, fsverity@lists.linux.dev, linux-block@vger.kernel.org, dm-devel@lists.linux.dev, audit@vger.kernel.org, linux-kernel@vger.kernel.org, Deven Bowers , Fan Wu Subject: [RFC PATCH v15 10/21] ipe: add permissive toggle Date: Fri, 15 Mar 2024 20:35:40 -0700 Message-Id: <1710560151-28904-11-git-send-email-wufan@linux.microsoft.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1710560151-28904-1-git-send-email-wufan@linux.microsoft.com> References: <1710560151-28904-1-git-send-email-wufan@linux.microsoft.com> Precedence: bulk X-Mailing-List: fsverity@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: From: Deven Bowers IPE, like SELinux, supports a permissive mode. This mode allows policy authors to test and evaluate IPE policy without it effecting their programs. When the mode is changed, a 1404 AUDIT_MAC_STATUS be reported. This patch adds the following audit records: audit: MAC_STATUS enforcing=0 old_enforcing=1 auid=4294967295 ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1 audit: MAC_STATUS enforcing=1 old_enforcing=0 auid=4294967295 ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1 The audit record only emit when the value from the user input is different from the current enforce value. Signed-off-by: Deven Bowers Signed-off-by: Fan Wu --- v2: + Split evaluation loop, access control hooks, and evaluation loop from policy parser and userspace interface to pass mailing list character limit v3: + Move ipe_load_properties to patch 04. + Remove useless 0-initializations + Prefix extern variables with ipe_ + Remove kernel module parameters, as these are exposed through sysctls. + Add more prose to the IPE base config option help text. + Use GFP_KERNEL for audit_log_start. + Remove unnecessary caching system. + Remove comments from headers + Use rcu_access_pointer for rcu-pointer null check + Remove usage of reqprot; use prot only. + Move policy load and activation audit event to 03/12 v4: + Remove sysctls in favor of securityfs nodes + Re-add kernel module parameters, as these are now exposed through securityfs. + Refactor property audit loop to a separate function. v5: + fix minor grammatical errors + do not group rule by curly-brace in audit record, reconstruct the exact rule. v6: + No changes v7: + Further split lsm creation into a separate commit from the evaluation loop and audit system, for easier review. + Propagating changes to support the new ipe_context structure in the evaluation loop. + Split out permissive functionality into a separate patch for easier review. + Remove permissive switch compile-time configuration option - this is trivial to add later. v8: + Remove "IPE" prefix from permissive audit record + align fields to the linux-audit field dictionary. This causes the following fields to change: enforce -> permissive + Remove duplicated information correlated with syscall record, that will always be present in the audit event. + Change audit types: + AUDIT_TRUST_STATUS -> AUDIT_MAC_STATUS + There is no significant difference in meaning between these types. v9: + Clean up ipe_context related code v10: + Change audit format to comform with the existing format selinux is using + Remove the audit record emission during init to align with selinux, which does not perform this action. v11: + Remove redundant code v12: + Remove redundant code v13: + Remove audit format macro v14: + No changes v15: + No changes --- security/ipe/audit.c | 27 ++++++++++++++++-- security/ipe/audit.h | 1 + security/ipe/eval.c | 11 +++++-- security/ipe/eval.h | 1 + security/ipe/fs.c | 68 ++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 104 insertions(+), 4 deletions(-) diff --git a/security/ipe/audit.c b/security/ipe/audit.c index f167fdc87986..a480f27278df 100644 --- a/security/ipe/audit.c +++ b/security/ipe/audit.c @@ -93,8 +93,8 @@ void ipe_audit_match(const struct ipe_eval_ctx *const ctx, if (!ab) return; - audit_log_format(ab, "ipe_op=%s ipe_hook=%s pid=%d comm=", - op, audit_hook_names[ctx->hook], + audit_log_format(ab, "ipe_op=%s ipe_hook=%s enforcing=%d pid=%d comm=", + op, audit_hook_names[ctx->hook], READ_ONCE(enforce), task_tgid_nr(current)); audit_log_untrustedstring(ab, get_task_comm(comm, current)); @@ -212,3 +212,26 @@ void ipe_audit_policy_load(const struct ipe_policy *const p) audit_log_end(ab); } + +/** + * ipe_audit_enforce - Audit a change in IPE's enforcement state. + * @new_enforce: The new value enforce to be set. + * @old_enforce: The old value currently in enforce. + */ +void ipe_audit_enforce(bool new_enforce, bool old_enforce) +{ + struct audit_buffer *ab; + + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_MAC_STATUS); + if (!ab) + return; + + audit_log(audit_context(), GFP_KERNEL, AUDIT_MAC_STATUS, + "enforcing=%d old_enforcing=%d auid=%u ses=%u" + " enabled=1 old-enabled=1 lsm=ipe res=1", + new_enforce, old_enforce, + from_kuid(&init_user_ns, audit_get_loginuid(current)), + audit_get_sessionid(current)); + + audit_log_end(ab); +} diff --git a/security/ipe/audit.h b/security/ipe/audit.h index 0ff5a06808de..914f001e5286 100644 --- a/security/ipe/audit.h +++ b/security/ipe/audit.h @@ -14,5 +14,6 @@ void ipe_audit_match(const struct ipe_eval_ctx *const ctx, void ipe_audit_policy_load(const struct ipe_policy *const p); void ipe_audit_policy_activation(const struct ipe_policy *const op, const struct ipe_policy *const np); +void ipe_audit_enforce(bool new_enforce, bool old_enforce); #endif /* _IPE_AUDIT_H */ diff --git a/security/ipe/eval.c b/security/ipe/eval.c index 274f7346ef42..3f3125478dd0 100644 --- a/security/ipe/eval.c +++ b/security/ipe/eval.c @@ -18,6 +18,7 @@ struct ipe_policy __rcu *ipe_active_policy; bool success_audit; +bool enforce = true; #define FILE_SUPERBLOCK(f) ((f)->f_path.mnt->mnt_sb) @@ -106,6 +107,7 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) const struct ipe_rule *rule = NULL; const struct ipe_op_table *rules = NULL; struct ipe_prop *prop = NULL; + int rc = 0; rcu_read_lock(); @@ -158,9 +160,12 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) ipe_audit_match(ctx, match_type, action, rule); if (action == IPE_ACTION_DENY) - return -EACCES; + rc = -EACCES; - return 0; + if (!READ_ONCE(enforce)) + rc = 0; + + return rc; } /* Set the right module name */ @@ -171,3 +176,5 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) module_param(success_audit, bool, 0400); MODULE_PARM_DESC(success_audit, "Start IPE with success auditing enabled"); +module_param(enforce, bool, 0400); +MODULE_PARM_DESC(enforce, "Start IPE in enforce or permissive mode"); diff --git a/security/ipe/eval.h b/security/ipe/eval.h index 4631b236358e..0b50302611a4 100644 --- a/security/ipe/eval.h +++ b/security/ipe/eval.h @@ -16,6 +16,7 @@ extern struct ipe_policy __rcu *ipe_active_policy; extern bool success_audit; +extern bool enforce; struct ipe_superblock { bool initramfs; diff --git a/security/ipe/fs.c b/security/ipe/fs.c index 95407997cf0c..b16d87443a3b 100644 --- a/security/ipe/fs.c +++ b/security/ipe/fs.c @@ -16,6 +16,7 @@ static struct dentry *np __ro_after_init; static struct dentry *root __ro_after_init; struct dentry *policy_root __ro_after_init; static struct dentry *audit_node __ro_after_init; +static struct dentry *enforce_node __ro_after_init; /** * setaudit - Write handler for the securityfs node, "ipe/success_audit" @@ -67,6 +68,60 @@ static ssize_t getaudit(struct file *f, char __user *data, return simple_read_from_buffer(data, len, offset, result, 1); } +/** + * setenforce - Write handler for the securityfs node, "ipe/enforce" + * @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 setenforce(struct file *f, const char __user *data, + size_t len, loff_t *offset) +{ + int rc = 0; + bool new_value, old_value; + + if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN)) + return -EPERM; + + old_value = READ_ONCE(enforce); + rc = kstrtobool_from_user(data, len, &new_value); + if (rc) + return rc; + + if (new_value != old_value) { + ipe_audit_enforce(new_value, old_value); + WRITE_ONCE(enforce, new_value); + } + + return len; +} + +/** + * getenforce - Read handler for the securityfs node, "ipe/enforce" + * @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 getenforce(struct file *f, char __user *data, + size_t len, loff_t *offset) +{ + const char *result; + + result = ((READ_ONCE(enforce)) ? "1" : "0"); + + return simple_read_from_buffer(data, len, offset, result, 1); +} + /** * new_policy - Write handler for the securityfs node, "ipe/new_policy". * @f: Supplies a file structure representing the securityfs node. @@ -120,6 +175,11 @@ static const struct file_operations audit_fops = { .read = getaudit, }; +static const struct file_operations enforce_fops = { + .write = setenforce, + .read = getenforce, +}; + /** * ipe_init_securityfs - Initialize IPE's securityfs tree at fsinit. * @@ -147,6 +207,13 @@ static int __init ipe_init_securityfs(void) goto err; } + enforce_node = securityfs_create_file("enforce", 0600, root, NULL, + &enforce_fops); + if (IS_ERR(enforce_node)) { + rc = PTR_ERR(enforce_node); + goto err; + } + policy_root = securityfs_create_dir("policies", root); if (IS_ERR(policy_root)) { rc = PTR_ERR(policy_root); @@ -163,6 +230,7 @@ static int __init ipe_init_securityfs(void) err: securityfs_remove(np); securityfs_remove(policy_root); + securityfs_remove(enforce_node); securityfs_remove(audit_node); securityfs_remove(root); return rc;