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| author | Daniel Borkmann <daniel@iogearbox.net> | 2021-05-11 22:35:17 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-05-11 13:56:16 -0700 |
| commit | 08389d888287c3823f80b0216766b71e17f0aba5 (patch) | |
| tree | 6d5c9fc6185c944141c44c00dcafa22901156908 /kernel/bpf | |
| parent | b24abcff918a5cbf44b0c982bd3477a93e8e4911 (diff) | |
| download | linux-08389d888287c3823f80b0216766b71e17f0aba5.tar.gz | |
bpf: Add kconfig knob for disabling unpriv bpf by default
Add a kconfig knob which allows for unprivileged bpf to be disabled by default.
If set, the knob sets /proc/sys/kernel/unprivileged_bpf_disabled to value of 2.
This still allows a transition of 2 -> {0,1} through an admin. Similarly,
this also still keeps 1 -> {1} behavior intact, so that once set to permanently
disabled, it cannot be undone aside from a reboot.
We've also added extra2 with max of 2 for the procfs handler, so that an admin
still has a chance to toggle between 0 <-> 2.
Either way, as an additional alternative, applications can make use of CAP_BPF
that we added a while ago.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/74ec548079189e4e4dffaeb42b8987bb3c852eee.1620765074.git.daniel@iogearbox.net
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/Kconfig | 10 | ||||
| -rw-r--r-- | kernel/bpf/syscall.c | 3 |
2 files changed, 12 insertions, 1 deletions
diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig index b4edaefc6255..26b591e23f16 100644 --- a/kernel/bpf/Kconfig +++ b/kernel/bpf/Kconfig @@ -61,6 +61,16 @@ 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" + 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). + source "kernel/bpf/preload/Kconfig" config BPF_LSM diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 941ca06d9dfa..ea04b0deb5ce 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -50,7 +50,8 @@ static DEFINE_SPINLOCK(map_idr_lock); static DEFINE_IDR(link_idr); static DEFINE_SPINLOCK(link_idr_lock); -int sysctl_unprivileged_bpf_disabled __read_mostly; +int sysctl_unprivileged_bpf_disabled __read_mostly = + IS_BUILTIN(CONFIG_BPF_UNPRIV_DEFAULT_OFF) ? 2 : 0; static const struct bpf_map_ops * const bpf_map_types[] = { #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) |