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Date: Thu, 23 Jul 2020 19:12:27 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: linux-kernel@...r.kernel.org
Cc: Mickaël Salaün <mic@...ikod.net>,
	Aleksa Sarai <cyphar@...har.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	Christian Brauner <christian.brauner@...ntu.com>,
	Christian Heimes <christian@...hon.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Deven Bowers <deven.desai@...ux.microsoft.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Eric Biggers <ebiggers@...nel.org>,
	Eric Chiang <ericchiang@...gle.com>,
	Florian Weimer <fweimer@...hat.com>,
	James Morris <jmorris@...ei.org>,
	Jan Kara <jack@...e.cz>,
	Jann Horn <jannh@...gle.com>,
	Jonathan Corbet <corbet@....net>,
	Kees Cook <keescook@...omium.org>,
	Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
	Matthew Garrett <mjg59@...gle.com>,
	Matthew Wilcox <willy@...radead.org>,
	Michael Kerrisk <mtk.manpages@...il.com>,
	Mimi Zohar <zohar@...ux.ibm.com>,
	Philippe Trébuchet <philippe.trebuchet@....gouv.fr>,
	Scott Shell <scottsh@...rosoft.com>,
	Sean Christopherson <sean.j.christopherson@...el.com>,
	Shuah Khan <shuah@...nel.org>,
	Steve Dower <steve.dower@...hon.org>,
	Steve Grubb <sgrubb@...hat.com>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	Thibaut Sautereau <thibaut.sautereau@...p-os.org>,
	Vincent Strubel <vincent.strubel@....gouv.fr>,
	kernel-hardening@...ts.openwall.com,
	linux-api@...r.kernel.org,
	linux-integrity@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: [PATCH v7 7/7] ima: add policy support for the new file open MAY_OPENEXEC flag

From: Mimi Zohar <zohar@...ux.ibm.com>

The kernel has no way of differentiating between a file containing data
or code being opened by an interpreter.  The proposed O_MAYEXEC
openat2(2) flag bridges this gap by defining and enabling the
MAY_OPENEXEC flag.

This patch adds IMA policy support for the new MAY_OPENEXEC flag.

Example:
measure func=FILE_CHECK mask=^MAY_OPENEXEC
appraise func=FILE_CHECK appraise_type=imasig mask=^MAY_OPENEXEC

Signed-off-by: Mickaël Salaün <mic@...ikod.net>
Signed-off-by: Mimi Zohar <zohar@...ux.ibm.com>
Reviewed-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
Link: https://lore.kernel.org/r/1588167523-7866-3-git-send-email-zohar@linux.ibm.com
---
 Documentation/ABI/testing/ima_policy |  2 +-
 security/integrity/ima/ima_main.c    |  3 ++-
 security/integrity/ima/ima_policy.c  | 15 +++++++++++----
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index cd572912c593..caca46125fe0 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -31,7 +31,7 @@ Description:
 				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
 				[KEXEC_CMDLINE] [KEY_CHECK]
 			mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
-			       [[^]MAY_EXEC]
+			       [[^]MAY_EXEC] [[^]MAY_OPENEXEC]
 			fsmagic:= hex value
 			fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
 			uid:= decimal value
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index c1583d98c5e5..59fd1658a203 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -490,7 +490,8 @@ int ima_file_check(struct file *file, int mask)
 
 	security_task_getsecid(current, &secid);
 	return process_measurement(file, current_cred(), secid, NULL, 0,
-				   mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
+				   mask & (MAY_READ | MAY_WRITE |
+					   MAY_EXEC | MAY_OPENEXEC |
 					   MAY_APPEND), FILE_CHECK);
 }
 EXPORT_SYMBOL_GPL(ima_file_check);
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index e493063a3c34..6487f0b2afdd 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -406,7 +406,8 @@ static bool ima_match_keyring(struct ima_rule_entry *rule,
  * @cred: a pointer to a credentials structure for user validation
  * @secid: the secid of the task to be validated
  * @func: LIM hook identifier
- * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
+ * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC |
+ *			    MAY_OPENEXEC)
  * @keyring: keyring name to check in policy for KEY_CHECK func
  *
  * Returns true on rule match, false on failure.
@@ -527,7 +528,8 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
  *        being made
  * @secid: LSM secid of the task to be validated
  * @func: IMA hook identifier
- * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
+ * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC |
+ *			    MAY_OPENEXEC)
  * @pcr: set the pcr to extend
  * @template_desc: the template that should be used for this rule
  * @keyring: the keyring name, if given, to be used to check in the policy.
@@ -1091,6 +1093,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 				entry->mask = MAY_READ;
 			else if (strcmp(from, "MAY_APPEND") == 0)
 				entry->mask = MAY_APPEND;
+			else if (strcmp(from, "MAY_OPENEXEC") == 0)
+				entry->mask = MAY_OPENEXEC;
 			else
 				result = -EINVAL;
 			if (!result)
@@ -1422,14 +1426,15 @@ const char *const func_tokens[] = {
 
 #ifdef	CONFIG_IMA_READ_POLICY
 enum {
-	mask_exec = 0, mask_write, mask_read, mask_append
+	mask_exec = 0, mask_write, mask_read, mask_append, mask_openexec
 };
 
 static const char *const mask_tokens[] = {
 	"^MAY_EXEC",
 	"^MAY_WRITE",
 	"^MAY_READ",
-	"^MAY_APPEND"
+	"^MAY_APPEND",
+	"^MAY_OPENEXEC"
 };
 
 void *ima_policy_start(struct seq_file *m, loff_t *pos)
@@ -1518,6 +1523,8 @@ int ima_policy_show(struct seq_file *m, void *v)
 			seq_printf(m, pt(Opt_mask), mt(mask_read) + offset);
 		if (entry->mask & MAY_APPEND)
 			seq_printf(m, pt(Opt_mask), mt(mask_append) + offset);
+		if (entry->mask & MAY_OPENEXEC)
+			seq_printf(m, pt(Opt_mask), mt(mask_openexec) + offset);
 		seq_puts(m, " ");
 	}
 
-- 
2.27.0

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