Commit 4279adb0 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
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bpf: Add new bpf_task_storage_get proto with no deadlock detection 



The bpf_lsm and bpf_iter do not recur that will cause a deadlock.
The situation is similar to the bpf_pid_task_storage_lookup_elem()
which is called from the syscall map_lookup_elem.  It does not need
deadlock detection.  Otherwise, it will cause unnecessary failure
when calling the bpf_task_storage_get() helper.

This patch adds bpf_task_storage_get proto that does not do deadlock
detection.  It will be used by bpf_lsm and bpf_iter programs.

Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20221025184524.3526117-6-martin.lau@linux.dev


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent e8b02296

include/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -2520,6 +2520,7 @@ extern const struct bpf_func_proto bpf_ktime_get_coarse_ns_proto; 
extern const struct bpf_func_proto bpf_sock_from_file_proto;

extern const struct bpf_func_proto bpf_get_socket_ptr_cookie_proto;

extern const struct bpf_func_proto bpf_task_storage_get_recur_proto;

extern const struct bpf_func_proto bpf_task_storage_get_proto;

extern const struct bpf_func_proto bpf_task_storage_delete_recur_proto;

extern const struct bpf_func_proto bpf_for_each_map_elem_proto;

extern const struct bpf_func_proto bpf_btf_find_by_name_kind_proto;

kernel/bpf/bpf_task_storage.c

+28 −0
Original line number Diff line number Diff line
@@ -269,6 +269,23 @@ BPF_CALL_5(bpf_task_storage_get_recur, struct bpf_map *, map, struct task_struct 
	return (unsigned long)data;

}



/* *gfp_flags* is a hidden argument provided by the verifier */

BPF_CALL_5(bpf_task_storage_get, struct bpf_map *, map, struct task_struct *,

	   task, void *, value, u64, flags, gfp_t, gfp_flags)

{

	void *data;



	WARN_ON_ONCE(!bpf_rcu_lock_held());

	if (flags & ~BPF_LOCAL_STORAGE_GET_F_CREATE || !task)

		return (unsigned long)NULL;



	bpf_task_storage_lock();

	data = __bpf_task_storage_get(map, task, value, flags,

				      gfp_flags, true);

	bpf_task_storage_unlock();

	return (unsigned long)data;

}



BPF_CALL_2(bpf_task_storage_delete_recur, struct bpf_map *, map, struct task_struct *,

	   task)

{
@@ -342,6 +359,17 @@ const struct bpf_func_proto bpf_task_storage_get_recur_proto = { 
	.arg4_type = ARG_ANYTHING,

};



const struct bpf_func_proto bpf_task_storage_get_proto = {

	.func = bpf_task_storage_get,

	.gpl_only = false,

	.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,

	.arg1_type = ARG_CONST_MAP_PTR,

	.arg2_type = ARG_PTR_TO_BTF_ID,

	.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],

	.arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,

	.arg4_type = ARG_ANYTHING,

};



const struct bpf_func_proto bpf_task_storage_delete_recur_proto = {

	.func = bpf_task_storage_delete_recur,

	.gpl_only = false,

kernel/trace/bpf_trace.c

+4 −1
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#include <linux/types.h>

#include <linux/slab.h>

#include <linux/bpf.h>

#include <linux/bpf_verifier.h>

#include <linux/bpf_perf_event.h>

#include <linux/btf.h>

#include <linux/filter.h>
@@ -1488,7 +1489,9 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
	case BPF_FUNC_this_cpu_ptr:

		return &bpf_this_cpu_ptr_proto;

	case BPF_FUNC_task_storage_get:

		if (bpf_prog_check_recur(prog))

			return &bpf_task_storage_get_recur_proto;

		return &bpf_task_storage_get_proto;

	case BPF_FUNC_task_storage_delete:

		return &bpf_task_storage_delete_recur_proto;

	case BPF_FUNC_for_each_map_elem: