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Diffstat (limited to 'Documentation/admin-guide/sysctl/kernel.rst')
| -rw-r--r-- | Documentation/admin-guide/sysctl/kernel.rst | 56 |
1 files changed, 52 insertions, 4 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 3800fab1619b..cf33de56da27 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 =================== @@ -941,16 +970,35 @@ enabled, otherwise writing to this file will return ``-EBUSY``. The default value is 8. -perf_user_access (arm64 only) -================================= +perf_user_access (arm64 and riscv only) +======================================= + +Controls user space access for reading perf event counters. -Controls user space access for reading perf event counters. When set to 1, -user space can read performance monitor counter registers directly. +arm64 +===== The default value is 0 (access disabled). +When set to 1, user space can read performance monitor counter registers +directly. + See Documentation/arch/arm64/perf.rst for more information. +riscv +===== + +When set to 0, user space access is disabled. + +The default value is 1, user space can read performance monitor counter +registers through perf, any direct access without perf intervention will trigger +an illegal instruction. + +When set to 2, which enables legacy mode (user space has direct access to cycle +and insret CSRs only). Note that this legacy value is deprecated and will be +removed once all user space applications are fixed. + +Note that the time CSR is always directly accessible to all modes. pid_max ======= |