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From: Paul Moore <[email protected]>
To: [email protected], [email protected],
	[email protected], [email protected],
	[email protected],
	Kumar Kartikeya Dwivedi <[email protected]>,
	Jens Axboe <[email protected]>,
	Pavel Begunkov <[email protected]>
Subject: [RFC PATCH v2 9/9] Smack: Brutalist io_uring support with debug
Date: Wed, 11 Aug 2021 16:49:07 -0400	[thread overview]
Message-ID: <162871494794.63873.18299137802334845525.stgit@olly> (raw)
In-Reply-To: <162871480969.63873.9434591871437326374.stgit@olly>

From: Casey Schaufler <[email protected]>

Add Smack privilege checks for io_uring. Use CAP_MAC_OVERRIDE
for the override_creds case and CAP_MAC_ADMIN for creating a
polling thread. These choices are based on conjecture regarding
the intent of the surrounding code.

Signed-off-by: Casey Schaufler <[email protected]>
[PM: make the smack_uring_* funcs static]
Signed-off-by: Paul Moore <[email protected]>

---
v2:
- made the smack_uring_* funcs static
v1:
- initial draft
---
 security/smack/smack_lsm.c |   64 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 223a6da0e6dc..7fb094098f38 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4691,6 +4691,66 @@ static int smack_dentry_create_files_as(struct dentry *dentry, int mode,
 	return 0;
 }
 
+#ifdef CONFIG_IO_URING
+/**
+ * smack_uring_override_creds - Is io_uring cred override allowed?
+ * @new: the target creds
+ *
+ * Check to see if the current task is allowed to override it's credentials
+ * to service an io_uring operation.
+ */
+static int smack_uring_override_creds(const struct cred *new)
+{
+	struct task_smack *tsp = smack_cred(current_cred());
+	struct task_smack *nsp = smack_cred(new);
+
+#if 1
+	if (tsp->smk_task == nsp->smk_task)
+		pr_info("%s: Smack matches %s\n", __func__,
+			tsp->smk_task->smk_known);
+	else
+		pr_info("%s: Smack override check %s to %s\n", __func__,
+			tsp->smk_task->smk_known, nsp->smk_task->smk_known);
+#endif
+	/*
+	 * Allow the degenerate case where the new Smack value is
+	 * the same as the current Smack value.
+	 */
+	if (tsp->smk_task == nsp->smk_task)
+		return 0;
+
+#if 1
+	pr_info("%s: Smack sqpoll %s\n", __func__,
+		smack_privileged_cred(CAP_MAC_OVERRIDE, current_cred()) ?
+		"ok by Smack" : "disallowed (No CAP_MAC_OVERRIDE)");
+#endif
+	if (smack_privileged_cred(CAP_MAC_OVERRIDE, current_cred()))
+		return 0;
+
+	return -EPERM;
+}
+
+/**
+ * smack_uring_sqpoll - check if a io_uring polling thread can be created
+ *
+ * Check to see if the current task is allowed to create a new io_uring
+ * kernel polling thread.
+ */
+static int smack_uring_sqpoll(void)
+{
+#if 1
+	pr_info("%s: Smack new ring %s\n", __func__,
+		smack_privileged_cred(CAP_MAC_ADMIN, current_cred()) ?
+		"ok by Smack" : "disallowed (No CAP_MAC_ADMIN)");
+#endif
+	if (smack_privileged_cred(CAP_MAC_ADMIN, current_cred()))
+		return 0;
+
+	return -EPERM;
+}
+
+#endif /* CONFIG_IO_URING */
+
 struct lsm_blob_sizes smack_blob_sizes __lsm_ro_after_init = {
 	.lbs_cred = sizeof(struct task_smack),
 	.lbs_file = sizeof(struct smack_known *),
@@ -4843,6 +4903,10 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(inode_copy_up, smack_inode_copy_up),
 	LSM_HOOK_INIT(inode_copy_up_xattr, smack_inode_copy_up_xattr),
 	LSM_HOOK_INIT(dentry_create_files_as, smack_dentry_create_files_as),
+#ifdef CONFIG_IO_URING
+	LSM_HOOK_INIT(uring_override_creds, smack_uring_override_creds),
+	LSM_HOOK_INIT(uring_sqpoll, smack_uring_sqpoll),
+#endif
 };
 
 


  parent reply	other threads:[~2021-08-11 20:49 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-11 20:48 [RFC PATCH v2 0/9] Add LSM access controls and auditing to io_uring Paul Moore
2021-08-11 20:48 ` [RFC PATCH v2 1/9] audit: prepare audit_context for use in calling contexts beyond syscalls Paul Moore
2021-08-11 20:48 ` [RFC PATCH v2 2/9] audit,io_uring,io-wq: add some basic audit support to io_uring Paul Moore
2021-08-11 20:48 ` [RFC PATCH v2 3/9] audit: dev/test patch to force io_uring auditing Paul Moore
2021-08-11 20:48 ` [RFC PATCH v2 4/9] audit: add filtering for io_uring records Paul Moore
2021-08-11 20:48 ` [RFC PATCH v2 5/9] fs: add anon_inode_getfile_secure() similar to anon_inode_getfd_secure() Paul Moore
2021-08-12  9:32   ` Mickaël Salaün
2021-08-12 14:32     ` Paul Moore
2021-08-12 15:35       ` Mickaël Salaün
2021-08-11 20:48 ` [RFC PATCH v2 6/9] io_uring: convert io_uring to the secure anon inode interface Paul Moore
2021-08-11 20:48 ` [RFC PATCH v2 7/9] lsm,io_uring: add LSM hooks to io_uring Paul Moore
2021-08-11 20:49 ` [RFC PATCH v2 8/9] selinux: add support for the io_uring access controls Paul Moore
2021-08-11 20:49 ` Paul Moore [this message]
2021-08-31 14:44   ` [RFC PATCH v2 9/9] Smack: Brutalist io_uring support with debug Paul Moore
2021-08-31 15:03     ` Casey Schaufler
2021-08-31 16:43       ` Paul Moore
2021-08-24 20:57 ` [RFC PATCH v2 0/9] Add LSM access controls and auditing to io_uring Richard Guy Briggs
2021-08-24 22:27   ` Paul Moore
2021-08-25  1:36     ` Richard Guy Briggs
2021-08-26  1:16   ` Richard Guy Briggs
2021-08-26  1:34     ` Paul Moore
2021-08-26 16:32       ` Richard Guy Briggs
2021-08-26 19:14         ` Paul Moore
2021-08-27 13:35           ` Richard Guy Briggs
2021-08-27 19:49             ` Paul Moore
2021-08-28 15:03               ` Richard Guy Briggs
2021-08-29 15:18                 ` Paul Moore
2021-09-01 19:21                   ` Paul Moore
2021-09-10  0:58                     ` Richard Guy Briggs
2021-09-13 19:23                       ` Paul Moore
2021-09-14  1:50                         ` Paul Moore
2021-09-14  2:49                           ` Paul Moore
2021-09-15 12:29                             ` Richard Guy Briggs
2021-09-15 13:02                               ` Steve Grubb
2021-09-15 14:12                               ` Paul Moore

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