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,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Jens Axboe <axboe@kernel.dk>,
Pavel Begunkov <asml.silence@gmail.com>
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 <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]
Signed-off-by: Paul Moore <paul@paul-moore.com>
---
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
};
--
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next prev parent reply other threads:[~2021-08-11 20:50 UTC|newest]
Thread overview: 41+ 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
2021-10-02 13:16 ` Steve Grubb
2021-10-03 23:21 ` Paul Moore
2021-10-04 12:39 ` Richard Guy Briggs
2021-10-04 13:27 ` Paul Moore
2021-10-04 14:59 ` Steve Grubb
2021-10-28 20:07 ` Richard Guy Briggs
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