linux-kernel - [PATCH 2/2] io_uring: use security_uring

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Message-ID: <20241219211610.83638-2-hamzamahfooz@linux.microsoft.com>
Date: Thu, 19 Dec 2024 16:16:07 -0500
From: Hamza Mahfooz <hamzamahfooz@...ux.microsoft.com>
To: linux-security-module@...r.kernel.org,
	io-uring@...r.kernel.org
Cc: Hamza Mahfooz <hamzamahfooz@...ux.microsoft.com>,
	Jens Axboe <axboe@...nel.dk>,
	Pavel Begunkov <asml.silence@...il.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] io_uring: use security_uring_allowed()

To make use of the new LSM hook, call security_uring_allowed()
from io_uring_allowed() and while we are at it return error codes
from io_uring_allowed() instead of true/false.

Cc: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Hamza Mahfooz <hamzamahfooz@...ux.microsoft.com>
---
 io_uring/io_uring.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 06ff41484e29..0922bb0724c0 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3806,29 +3806,36 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
 	return io_uring_create(entries, &p, params);
 }
 
-static inline bool io_uring_allowed(void)
+static inline int io_uring_allowed(void)
 {
 	int disabled = READ_ONCE(sysctl_io_uring_disabled);
 	kgid_t io_uring_group;
 
 	if (disabled == 2)
-		return false;
+		return -EPERM;
 
 	if (disabled == 0 || capable(CAP_SYS_ADMIN))
-		return true;
+		goto allowed_lsm;
 
 	io_uring_group = make_kgid(&init_user_ns, sysctl_io_uring_group);
 	if (!gid_valid(io_uring_group))
-		return false;
+		return -EPERM;
+
+	if (!in_group_p(io_uring_group))
+		return -EPERM;
 
-	return in_group_p(io_uring_group);
+allowed_lsm:
+	return security_uring_allowed();
 }
 
 SYSCALL_DEFINE2(io_uring_setup, u32, entries,
 		struct io_uring_params __user *, params)
 {
-	if (!io_uring_allowed())
-		return -EPERM;
+	int ret;
+
+	ret = io_uring_allowed();
+	if (ret)
+		return ret;
 
 	return io_uring_setup(entries, params);
 }
-- 
2.47.1