[PATCH bpf-next v6 0/2] bpf: enable some functions in cgroup programs

[PATCH bpf-next v6 0/2] bpf: enable some functions in cgroup programs

[Matteo Croce]

From: Matteo Croce <teknoraver@meta.com>

Enable some BPF kfuncs and the helper bpf_current_task_under_cgroup()
for program types BPF_CGROUP_*.
These will be used by systemd-networkd:
https://github.com/systemd/systemd/pull/32212

v5->v6:
Called register_btf_kfunc_id_set() only once
Fixed build error with !CONFIG_CGROUPS

v4->v5:
Same code, but v4 had an old cover letter

v3->v4:
Reset all the acked-by tags because the code changed a bit.

Signed-off-by: Matteo Croce <teknoraver@meta.com>

Matteo Croce (2):
  bpf: enable generic kfuncs for BPF_CGROUP_* programs
  bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP_*

 include/linux/bpf.h      |  1 +
 kernel/bpf/btf.c         |  8 ++++++--
 kernel/bpf/cgroup.c      |  2 ++
 kernel/bpf/helpers.c     | 24 ++++++++++++++++++++++++
 kernel/trace/bpf_trace.c | 27 ++-------------------------
 5 files changed, 35 insertions(+), 27 deletions(-)

-- 
2.46.0

[PATCH bpf-next v6 1/2] bpf: enable generic kfuncs for BPF_CGROUP_* programs

[Matteo Croce]

From: Matteo Croce <teknoraver@meta.com>

These kfuncs are enabled even in BPF_PROG_TYPE_TRACING, so they
should be safe also in BPF_CGROUP_* programs.
Since all BPF_CGROUP_* programs share the same hook,
call register_btf_kfunc_id_set() only once.

In enum btf_kfunc_hook, rename BTF_KFUNC_HOOK_CGROUP_SKB to a more
generic BTF_KFUNC_HOOK_CGROUP, since it's used for all the cgroup
related program types.

Signed-off-by: Matteo Croce <teknoraver@meta.com>
---
 kernel/bpf/btf.c     | 8 ++++++--
 kernel/bpf/helpers.c | 1 +
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index bfb0d89ccc8b..b12db397303e 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -212,7 +212,7 @@ enum btf_kfunc_hook {
 	BTF_KFUNC_HOOK_TRACING,
 	BTF_KFUNC_HOOK_SYSCALL,
 	BTF_KFUNC_HOOK_FMODRET,
-	BTF_KFUNC_HOOK_CGROUP_SKB,
+	BTF_KFUNC_HOOK_CGROUP,
 	BTF_KFUNC_HOOK_SCHED_ACT,
 	BTF_KFUNC_HOOK_SK_SKB,
 	BTF_KFUNC_HOOK_SOCKET_FILTER,
@@ -8307,8 +8307,12 @@ static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
 	case BPF_PROG_TYPE_SYSCALL:
 		return BTF_KFUNC_HOOK_SYSCALL;
 	case BPF_PROG_TYPE_CGROUP_SKB:
+	case BPF_PROG_TYPE_CGROUP_SOCK:
+	case BPF_PROG_TYPE_CGROUP_DEVICE:
 	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
-		return BTF_KFUNC_HOOK_CGROUP_SKB;
+	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
+	case BPF_PROG_TYPE_CGROUP_SYSCTL:
+		return BTF_KFUNC_HOOK_CGROUP;
 	case BPF_PROG_TYPE_SCHED_ACT:
 		return BTF_KFUNC_HOOK_SCHED_ACT;
 	case BPF_PROG_TYPE_SK_SKB:
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index d02ae323996b..26b9649ab4ce 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -3052,6 +3052,7 @@ static int __init kfunc_init(void)
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &generic_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &generic_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &generic_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SKB, &generic_kfunc_set);
 	ret = ret ?: register_btf_id_dtor_kfuncs(generic_dtors,
 						  ARRAY_SIZE(generic_dtors),
 						  THIS_MODULE);
-- 
2.46.0

[PATCH bpf-next v6 2/2] bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP_*

[Matteo Croce]

From: Matteo Croce <teknoraver@meta.com>

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>
---
 include/linux/bpf.h      |  1 +
 kernel/bpf/cgroup.c      |  2 ++
 kernel/bpf/helpers.c     | 23 +++++++++++++++++++++++
 kernel/trace/bpf_trace.c | 27 ++-------------------------
 4 files changed, 28 insertions(+), 25 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b9425e410bcb..f0192c173ed8 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -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;
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 8ba73042a239..e7113d700b87 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -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;
 	}
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 26b9649ab4ce..12e3aa40b180 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -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
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index d557bb11e0ff..b69a39316c0c 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -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;
-- 
2.46.0

Re: [PATCH bpf-next v6 0/2] bpf: enable some functions in cgroup programs

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Mon, 19 Aug 2024 18:28:03 +0200 you wrote:
> From: Matteo Croce <teknoraver@meta.com>
> 
> Enable some BPF kfuncs and the helper bpf_current_task_under_cgroup()
> for program types BPF_CGROUP_*.
> These will be used by systemd-networkd:
> https://github.com/systemd/systemd/pull/32212
> 
> [...]

Here is the summary with links:
  - [bpf-next,v6,1/2] bpf: enable generic kfuncs for BPF_CGROUP_* programs
    https://git.kernel.org/bpf/bpf-next/c/67666479edf1
  - [bpf-next,v6,2/2] bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP_*
    https://git.kernel.org/bpf/bpf-next/c/7f6287417baf

You are awesome, thank you!
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