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authorMatteo Rizzo <matteorizzo@google.com>2023-08-22 00:15:52 +0300
committerJens Axboe <axboe@kernel.dk>2023-09-05 17:34:07 +0300
commit76d3ccecfa186af3120e206d62f03db1a94a535f (patch)
tree8b3760ca153fe6e034e0caaaf7558055ad88afa3 /Documentation/admin-guide/sysctl
parent32f5dea040ee6e3cc30ac52d23f1674fd5110d03 (diff)
downloadlinux-76d3ccecfa186af3120e206d62f03db1a94a535f.tar.xz
io_uring: add a sysctl to disable io_uring system-wide
Introduce a new sysctl (io_uring_disabled) which can be either 0, 1, or 2. When 0 (the default), all processes are allowed to create io_uring instances, which is the current behavior. When 1, io_uring creation is disabled (io_uring_setup() will fail with -EPERM) for unprivileged processes not in the kernel.io_uring_group group. When 2, calls to io_uring_setup() fail with -EPERM regardless of privilege. Signed-off-by: Matteo Rizzo <matteorizzo@google.com> [JEM: modified to add io_uring_group] Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Link: https://lore.kernel.org/r/x49y1i42j1z.fsf@segfault.boston.devel.redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'Documentation/admin-guide/sysctl')
-rw-r--r--Documentation/admin-guide/sysctl/kernel.rst29
1 files changed, 29 insertions, 0 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 3800fab1619b..0795d790cc56 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -450,6 +450,35 @@ this allows system administrators to override the
``IA64_THREAD_UAC_NOPRINT`` ``prctl`` and avoid logs being flooded.
+io_uring_disabled
+=================
+
+Prevents all processes from creating new io_uring instances. Enabling this
+shrinks the kernel's attack surface.
+
+= ======================================================================
+0 All processes can create io_uring instances as normal. This is the
+ default setting.
+1 io_uring creation is disabled (io_uring_setup() will fail with
+ -EPERM) for unprivileged processes not in the io_uring_group group.
+ Existing io_uring instances can still be used. See the
+ documentation for io_uring_group for more information.
+2 io_uring creation is disabled for all processes. io_uring_setup()
+ always fails with -EPERM. Existing io_uring instances can still be
+ used.
+= ======================================================================
+
+
+io_uring_group
+==============
+
+When io_uring_disabled is set to 1, a process must either be
+privileged (CAP_SYS_ADMIN) or be in the io_uring_group group in order
+to create an io_uring instance. If io_uring_group is set to -1 (the
+default), only processes with the CAP_SYS_ADMIN capability may create
+io_uring instances.
+
+
kexec_load_disabled
===================