bpf: Fail PERF_EVENT_IOC_SET_BPF when bpf_get_[stack|stackid] cannot work (5d99cb2c) · Commits · 戴 / test

include/linux/filter.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -533,7 +533,8 @@ struct bpf_prog {
		is_func:1, /* program is a bpf function */
		kprobe_override:1, /* Do we override a kprobe? */
		has_callchain_buf:1, /* callchain buffer allocated? */
		enforce_expected_attach_type:1; /* Enforce expected_attach_type checking at attach time */
		enforce_expected_attach_type:1, /* Enforce expected_attach_type checking at attach time */
		call_get_stack:1; /* Do we call bpf_get_stack() or bpf_get_stackid() */
		enum bpf_prog_type type; /* Type of BPF program */
		enum bpf_attach_type expected_attach_type; /* For some prog types */
		u32 len; /* Number of filter blocks */

+3 −0

Original line number	Diff line number	Diff line
		@@ -4962,6 +4962,9 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
		env->prog->has_callchain_buf = true;
		}

		if (func_id == BPF_FUNC_get_stackid \|\| func_id == BPF_FUNC_get_stack)
		env->prog->call_get_stack = true;

		if (changes_data)
		clear_all_pkt_pointers(env);
		return 0;

+18 −0

Original line number	Diff line number	Diff line
		@@ -9544,6 +9544,24 @@ static int perf_event_set_bpf_handler(struct perf_event *event, u32 prog_fd)
		if (IS_ERR(prog))
		return PTR_ERR(prog);

		if (event->attr.precise_ip &&
		prog->call_get_stack &&
		(!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY) \|\|
		event->attr.exclude_callchain_kernel \|\|
		event->attr.exclude_callchain_user)) {
		/*
		* On perf_event with precise_ip, calling bpf_get_stack()
		* may trigger unwinder warnings and occasional crashes.
		* bpf_get_[stack\|stackid] works around this issue by using
		* callchain attached to perf_sample_data. If the
		* perf_event does not full (kernel and user) callchain
		* attached to perf_sample_data, do not allow attaching BPF
		* program that calls bpf_get_[stack\|stackid].
		*/
		bpf_prog_put(prog);
		return -EPROTO;
		}

		event->prog = prog;
		event->orig_overflow_handler = READ_ONCE(event->overflow_handler);
		WRITE_ONCE(event->overflow_handler, bpf_overflow_handler);