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bpf: Allow bpf_current_task_under_cgroup() with BPF_CGROUP_*

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The helper bpf_current_task_under_cgroup() currently is only allowed for
tracing programs, allow its usage also in the BPF_CGROUP_* program types.

Move the code from kernel/trace/bpf_trace.c to kernel/bpf/helpers.c,
so it compiles also without CONFIG_BPF_EVENTS.

This will be used in systemd-networkd to monitor the sysctl writes,
and filter it's own writes from others:
https://github.com/systemd/systemd/pull/32212

Signed-off-by: Matteo Croce <teknoraver@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240819162805.78235-3-technoboy85@gmail.com
This commit is contained in:
Matteo Croce 2024-08-19 18:28:05 +02:00 committed by Andrii Nakryiko
parent 67666479ed
commit 7f6287417b
4 changed files with 28 additions and 25 deletions
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1
include/linux/bpf.h
View File

@ -3206,6 +3206,7 @@ extern const struct bpf_func_proto bpf_sock_hash_update_proto;
extern const struct bpf_func_proto bpf_get_current_cgroup_id_proto;
extern const struct bpf_func_proto bpf_get_current_ancestor_cgroup_id_proto;
extern const struct bpf_func_proto bpf_get_cgroup_classid_curr_proto;
extern const struct bpf_func_proto bpf_current_task_under_cgroup_proto;
extern const struct bpf_func_proto bpf_msg_redirect_hash_proto;
extern const struct bpf_func_proto bpf_msg_redirect_map_proto;
extern const struct bpf_func_proto bpf_sk_redirect_hash_proto;

2
kernel/bpf/cgroup.c
View File

@ -2581,6 +2581,8 @@ cgroup_current_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_get_cgroup_classid:
return &bpf_get_cgroup_classid_curr_proto;
#endif
case BPF_FUNC_current_task_under_cgroup:
return &bpf_current_task_under_cgroup_proto;
default:
return NULL;
}

23
kernel/bpf/helpers.c
View File

@ -2458,6 +2458,29 @@ __bpf_kfunc long bpf_task_under_cgroup(struct task_struct *task,
return ret;
}
BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct cgroup *cgrp;
if (unlikely(idx >= array->map.max_entries))
return -E2BIG;
cgrp = READ_ONCE(array->ptrs[idx]);
if (unlikely(!cgrp))
return -EAGAIN;
return task_under_cgroup_hierarchy(current, cgrp);
}
const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
.func = bpf_current_task_under_cgroup,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_CONST_MAP_PTR,
.arg2_type = ARG_ANYTHING,
};
/**
* bpf_task_get_cgroup1 - Acquires the associated cgroup of a task within a
* specific cgroup1 hierarchy. The cgroup1 hierarchy is identified by its

27
kernel/trace/bpf_trace.c
View File

@ -797,29 +797,6 @@ const struct bpf_func_proto bpf_task_pt_regs_proto = {
.ret_btf_id = &bpf_task_pt_regs_ids[0],
};
BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct cgroup *cgrp;
if (unlikely(idx >= array->map.max_entries))
return -E2BIG;
cgrp = READ_ONCE(array->ptrs[idx]);
if (unlikely(!cgrp))
return -EAGAIN;
return task_under_cgroup_hierarchy(current, cgrp);
}
static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
.func = bpf_current_task_under_cgroup,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_CONST_MAP_PTR,
.arg2_type = ARG_ANYTHING,
};
struct send_signal_irq_work {
struct irq_work irq_work;
struct task_struct *task;
@ -1480,8 +1457,6 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_get_numa_node_id_proto;
case BPF_FUNC_perf_event_read:
return &bpf_perf_event_read_proto;
case BPF_FUNC_current_task_under_cgroup:
return &bpf_current_task_under_cgroup_proto;
case BPF_FUNC_get_prandom_u32:
return &bpf_get_prandom_u32_proto;
case BPF_FUNC_probe_write_user:
@ -1510,6 +1485,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_cgrp_storage_get_proto;
case BPF_FUNC_cgrp_storage_delete:
return &bpf_cgrp_storage_delete_proto;
case BPF_FUNC_current_task_under_cgroup:
return &bpf_current_task_under_cgroup_proto;
#endif
case BPF_FUNC_send_signal:
return &bpf_send_signal_proto;