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bpf: Add new bpf_task_storage_get proto with no deadlock detection

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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: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20221025184524.3526117-6-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Martin KaFai Lau 2022-10-25 11:45:20 -07:00 committed by Alexei Starovoitov
parent e8b02296a6
commit 4279adb094
3 changed files with 33 additions and 1 deletions
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1
include/linux/bpf.h
View File

@ -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;

28
kernel/bpf/bpf_task_storage.c
View File

@ -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,

5
kernel/trace/bpf_trace.c
View File

@ -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:
return &bpf_task_storage_get_recur_proto;
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: