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authorPawan Gupta <pawan.kumar.gupta@linux.intel.com>2021-10-29 22:43:54 +0300
committerDaniel Borkmann <daniel@iogearbox.net>2021-11-01 19:06:47 +0300
commit8a03e56b253e9691c90bc52ca199323d71b96204 (patch)
tree5c4bdf42553fc742175e01f490a591088cf75468
parentf48ad69097fe79d1de13c4d8fef556d4c11c5e68 (diff)
downloadlinux-8a03e56b253e9691c90bc52ca199323d71b96204.tar.xz
bpf: Disallow unprivileged bpf by default
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 08389d888287 ("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
-rw-r--r--kernel/bpf/Kconfig7
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
index a82d6de86522..d24d518ddd63 100644
--- a/kernel/bpf/Kconfig
+++ b/kernel/bpf/Kconfig
@@ -64,6 +64,7 @@ config BPF_JIT_DEFAULT_ON
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
@@ -72,6 +73,12 @@ config BPF_UNPRIV_DEFAULT_OFF
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