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From: Paul Moore <paul@paul-moore.com>
To: linux-security-module@vger.kernel.org, selinux@vger.kernel.org,
	linux-audit@redhat.com, io-uring@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
	Pavel Begunkov <asml.silence@gmail.com>,
	Kumar Kartikeya Dwivedi <memxor@gmail.com>
Subject: [PATCH v3 8/8] Smack: Brutalist io_uring support with debug
Date: Mon, 13 Sep 2021 23:33:41 -0400	[thread overview]
Message-ID: <163159042110.470089.9405201508228711833.stgit@olly> (raw)
In-Reply-To: <163159032713.470089.11728103630366176255.stgit@olly>

From: Casey Schaufler <casey@schaufler-ca.com>

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 <casey@schaufler-ca.com>
[PM: make the smack_uring_* funcs static, remove debug code]
Signed-off-by: Paul Moore <paul@paul-moore.com>

---
v3:
- removed debug code
v2:
- made the smack_uring_* funcs static
v1:
- initial draft
---
 security/smack/smack_lsm.c |   46 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index cacbe7518519..f90ab1efeb6d 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4691,6 +4691,48 @@ 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);
+
+	/*
+	 * 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 (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 (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 +4885,10 @@ 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:[~2021-09-14  3:34 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-14  3:32 [PATCH v3 0/8] Add LSM access controls and auditing to io_uring Paul Moore
2021-09-14  3:32 ` [PATCH v3 1/8] audit: prepare audit_context for use in calling contexts beyond syscalls Paul Moore
2021-09-14  3:33 ` [PATCH v3 2/8] audit,io_uring,io-wq: add some basic audit support to io_uring Paul Moore
2021-09-14  3:33 ` [PATCH v3 3/8] audit: add filtering for io_uring records Paul Moore
2021-09-14  3:33 ` [PATCH v3 4/8] fs: add anon_inode_getfile_secure() similar to anon_inode_getfd_secure() Paul Moore
2021-09-14  3:33 ` [PATCH v3 5/8] io_uring: convert io_uring to the secure anon inode interface Paul Moore
2021-09-14  3:33 ` [PATCH v3 6/8] lsm,io_uring: add LSM hooks to io_uring Paul Moore
2021-09-14  3:33 ` [PATCH v3 7/8] selinux: add support for the io_uring access controls Paul Moore
2021-09-14  3:33 ` Paul Moore [this message]

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