mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-11-01 00:48:50 +00:00
8a03e56b25
Disabling unprivileged BPF would help prevent unprivileged users from
creating certain conditions required for potential speculative execution
side-channel attacks on unmitigated affected hardware.
A deep dive on such attacks and current mitigations is available here [0].
Sync with what many distros are currently applying already, and disable
unprivileged BPF by default. An admin can enable this at runtime, if
necessary, as described in 08389d8882 ("bpf: Add kconfig knob for
disabling unpriv bpf by default").
[0] "BPF and Spectre: Mitigating transient execution attacks", Daniel Borkmann, eBPF Summit '21
https://ebpf.io/summit-2021-slides/eBPF_Summit_2021-Keynote-Daniel_Borkmann-BPF_and_Spectre.pdf
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/bpf/0ace9ce3f97656d5f62d11093ad7ee81190c3c25.1635535215.git.pawan.kumar.gupta@linux.intel.com
96 lines
2.8 KiB
Text
96 lines
2.8 KiB
Text
# SPDX-License-Identifier: GPL-2.0-only
|
|
|
|
# BPF interpreter that, for example, classic socket filters depend on.
|
|
config BPF
|
|
bool
|
|
|
|
# Used by archs to tell that they support BPF JIT compiler plus which
|
|
# flavour. Only one of the two can be selected for a specific arch since
|
|
# eBPF JIT supersedes the cBPF JIT.
|
|
|
|
# Classic BPF JIT (cBPF)
|
|
config HAVE_CBPF_JIT
|
|
bool
|
|
|
|
# Extended BPF JIT (eBPF)
|
|
config HAVE_EBPF_JIT
|
|
bool
|
|
|
|
# Used by archs to tell that they want the BPF JIT compiler enabled by
|
|
# default for kernels that were compiled with BPF JIT support.
|
|
config ARCH_WANT_DEFAULT_BPF_JIT
|
|
bool
|
|
|
|
menu "BPF subsystem"
|
|
|
|
config BPF_SYSCALL
|
|
bool "Enable bpf() system call"
|
|
select BPF
|
|
select IRQ_WORK
|
|
select TASKS_TRACE_RCU
|
|
select BINARY_PRINTF
|
|
select NET_SOCK_MSG if NET
|
|
default n
|
|
help
|
|
Enable the bpf() system call that allows to manipulate BPF programs
|
|
and maps via file descriptors.
|
|
|
|
config BPF_JIT
|
|
bool "Enable BPF Just In Time compiler"
|
|
depends on BPF
|
|
depends on HAVE_CBPF_JIT || HAVE_EBPF_JIT
|
|
depends on MODULES
|
|
help
|
|
BPF programs are normally handled by a BPF interpreter. This option
|
|
allows the kernel to generate native code when a program is loaded
|
|
into the kernel. This will significantly speed-up processing of BPF
|
|
programs.
|
|
|
|
Note, an admin should enable this feature changing:
|
|
/proc/sys/net/core/bpf_jit_enable
|
|
/proc/sys/net/core/bpf_jit_harden (optional)
|
|
/proc/sys/net/core/bpf_jit_kallsyms (optional)
|
|
|
|
config BPF_JIT_ALWAYS_ON
|
|
bool "Permanently enable BPF JIT and remove BPF interpreter"
|
|
depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
|
|
help
|
|
Enables BPF JIT and removes BPF interpreter to avoid speculative
|
|
execution of BPF instructions by the interpreter.
|
|
|
|
config BPF_JIT_DEFAULT_ON
|
|
def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
|
|
depends on HAVE_EBPF_JIT && BPF_JIT
|
|
|
|
config BPF_UNPRIV_DEFAULT_OFF
|
|
bool "Disable unprivileged BPF by default"
|
|
default y
|
|
depends on BPF_SYSCALL
|
|
help
|
|
Disables unprivileged BPF by default by setting the corresponding
|
|
/proc/sys/kernel/unprivileged_bpf_disabled knob to 2. An admin can
|
|
still reenable it by setting it to 0 later on, or permanently
|
|
disable it by setting it to 1 (from which no other transition to
|
|
0 is possible anymore).
|
|
|
|
Unprivileged BPF could be used to exploit certain potential
|
|
speculative execution side-channel vulnerabilities on unmitigated
|
|
affected hardware.
|
|
|
|
If you are unsure how to answer this question, answer Y.
|
|
|
|
source "kernel/bpf/preload/Kconfig"
|
|
|
|
config BPF_LSM
|
|
bool "Enable BPF LSM Instrumentation"
|
|
depends on BPF_EVENTS
|
|
depends on BPF_SYSCALL
|
|
depends on SECURITY
|
|
depends on BPF_JIT
|
|
help
|
|
Enables instrumentation of the security hooks with BPF programs for
|
|
implementing dynamic MAC and Audit Policies.
|
|
|
|
If you are unsure how to answer this question, answer N.
|
|
|
|
endmenu # "BPF subsystem"
|