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Date: Mon, 11 Jul 2022 10:32:19 +0200
From: Artem Savkov <asavkov@...hat.com>
To: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org,
netdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
Andrea Arcangeli <aarcange@...hat.com>,
Artem Savkov <asavkov@...hat.com>
Subject: [RFC PATCH bpf-next 3/4] bpf: add bpf_panic() helper
Add a helper that will make the kernel panic immediately with specified
message. Using this helper requires kernel.destructive_bpf_enabled sysctl
to be enabled, BPF_F_DESTRUCTIVE flag to be supplied on program load as
well as CAP_SYS_BOOT capabilities.
Signed-off-by: Artem Savkov <asavkov@...hat.com>
---
include/linux/bpf.h | 1 +
include/uapi/linux/bpf.h | 7 +++++++
kernel/bpf/core.c | 1 +
kernel/bpf/helpers.c | 13 +++++++++++++
kernel/bpf/verifier.c | 7 +++++++
kernel/trace/bpf_trace.c | 2 ++
tools/include/uapi/linux/bpf.h | 7 +++++++
7 files changed, 38 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 43c008e3587a..77c20ba9ca8e 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2339,6 +2339,7 @@ extern const struct bpf_func_proto bpf_strtol_proto;
extern const struct bpf_func_proto bpf_strtoul_proto;
extern const struct bpf_func_proto bpf_tcp_sock_proto;
extern const struct bpf_func_proto bpf_jiffies64_proto;
+extern const struct bpf_func_proto bpf_panic_proto;
extern const struct bpf_func_proto bpf_get_ns_current_pid_tgid_proto;
extern const struct bpf_func_proto bpf_event_output_data_proto;
extern const struct bpf_func_proto bpf_ringbuf_output_proto;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 4423874b5da4..e2e2c4de44ee 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3927,6 +3927,12 @@ union bpf_attr {
* Return
* The 64 bit jiffies
*
+ * void bpf_panic(const char *msg)
+ * Description
+ * Make the kernel panic immediately
+ * Return
+ * void
+ *
* long bpf_read_branch_records(struct bpf_perf_event_data *ctx, void *buf, u32 size, u64 flags)
* Description
* For an eBPF program attached to a perf event, retrieve the
@@ -5452,6 +5458,7 @@ union bpf_attr {
FN(tcp_send_ack), \
FN(send_signal_thread), \
FN(jiffies64), \
+ FN(panic), \
FN(read_branch_records), \
FN(get_ns_current_pid_tgid), \
FN(xdp_output), \
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index b5ffebcce6cc..0f333a0e85a5 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2649,6 +2649,7 @@ const struct bpf_func_proto bpf_map_lookup_percpu_elem_proto __weak;
const struct bpf_func_proto bpf_spin_lock_proto __weak;
const struct bpf_func_proto bpf_spin_unlock_proto __weak;
const struct bpf_func_proto bpf_jiffies64_proto __weak;
+const struct bpf_func_proto bpf_panic_proto __weak;
const struct bpf_func_proto bpf_get_prandom_u32_proto __weak;
const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak;
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index a1c84d256f83..5cb90208a264 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -374,6 +374,19 @@ const struct bpf_func_proto bpf_jiffies64_proto = {
.ret_type = RET_INTEGER,
};
+BPF_CALL_1(bpf_panic, const char *, msg)
+{
+ panic(msg);
+ return 0;
+}
+
+const struct bpf_func_proto bpf_panic_proto = {
+ .func = bpf_panic,
+ .gpl_only = false,
+ .ret_type = RET_VOID,
+ .arg1_type = ARG_PTR_TO_CONST_STR,
+};
+
#ifdef CONFIG_CGROUPS
BPF_CALL_0(bpf_get_current_cgroup_id)
{
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2859901ffbe3..f49c026917c5 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7285,6 +7285,13 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
reg_type_str(env, regs[BPF_REG_1].type));
return -EACCES;
}
+ break;
+ case BPF_FUNC_panic:
+ struct bpf_prog_aux *aux = env->prog->aux;
+ if (!aux->destructive) {
+ verbose(env, "bpf_panic() calls require BPF_F_DESTRUCTIVE flag\n");
+ return -EACCES;
+ }
}
if (err)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 4be976cf7d63..3ee888507795 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1304,6 +1304,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_find_vma_proto;
case BPF_FUNC_trace_vprintk:
return bpf_get_trace_vprintk_proto();
+ case BPF_FUNC_panic:
+ return capable(CAP_SYS_BOOT) && destructive_ebpf_enabled() ? &bpf_panic_proto : NULL;
default:
return bpf_base_func_proto(func_id);
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 4423874b5da4..e2e2c4de44ee 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3927,6 +3927,12 @@ union bpf_attr {
* Return
* The 64 bit jiffies
*
+ * void bpf_panic(const char *msg)
+ * Description
+ * Make the kernel panic immediately
+ * Return
+ * void
+ *
* long bpf_read_branch_records(struct bpf_perf_event_data *ctx, void *buf, u32 size, u64 flags)
* Description
* For an eBPF program attached to a perf event, retrieve the
@@ -5452,6 +5458,7 @@ union bpf_attr {
FN(tcp_send_ack), \
FN(send_signal_thread), \
FN(jiffies64), \
+ FN(panic), \
FN(read_branch_records), \
FN(get_ns_current_pid_tgid), \
FN(xdp_output), \
--
2.35.3
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