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authorDaniel Borkmann <daniel@iogearbox.net>2021-05-11 22:35:17 +0200
committerAlexei Starovoitov <ast@kernel.org>2021-05-11 13:56:16 -0700
commit08389d888287c3823f80b0216766b71e17f0aba5 (patch)
tree6d5c9fc6185c944141c44c00dcafa22901156908 /kernel/bpf
parentb24abcff918a5cbf44b0c982bd3477a93e8e4911 (diff)
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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/Kconfig10
-rw-r--r--kernel/bpf/syscall.c3
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)