From 3ec482d15cb986bf08b923f9193eeddb3b9ca69f Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Mon, 8 Apr 2019 10:51:01 -0600
Subject: [PATCH] io_uring: restrict IORING_SETUP_SQPOLL to root
This options spawns a kernel side thread that will poll for submissions
(and completions, if IORING_SETUP_IOPOLL is set). As this allows a user
to potentially use more cycles outside of the normal hierarchy,
restrict the use of this feature to root.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
fs/io_uring.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 07d6ef195d05a..89aa8412b5f59 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2245,6 +2245,10 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx,
goto err;
if (ctx->flags & IORING_SETUP_SQPOLL) {
+ ret = -EPERM;
+ if (!capable(CAP_SYS_ADMIN))
+ goto err;
+
if (p->flags & IORING_SETUP_SQ_AFF) {
int cpu;
--
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