linux-kernel - [PATCH bpf-next v7 07/24] bpf: prepare for more bpf syscall to be used from kernel and user space.

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Message-Id: <20220721153625.1282007-8-benjamin.tissoires@redhat.com>
Date:   Thu, 21 Jul 2022 17:36:08 +0200
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Greg KH <gregkh@...uxfoundation.org>,
        Jiri Kosina <jikos@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Kumar Kartikeya Dwivedi <memxor@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, Shuah Khan <shuah@...nel.org>,
        Dave Marchevsky <davemarchevsky@...com>,
        Joe Stringer <joe@...ium.io>, Jonathan Corbet <corbet@....net>
Cc:     Tero Kristo <tero.kristo@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-doc@...r.kernel.org,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Subject: [PATCH bpf-next v7 07/24] bpf: prepare for more bpf syscall to be used from kernel and user space.

Add BPF_MAP_GET_FD_BY_ID and BPF_MAP_DELETE_PROG.

Only BPF_MAP_GET_FD_BY_ID needs to be amended to be able
to access the bpf pointer either from the userspace or the kernel.

Acked-by: Yonghong Song <yhs@...com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>

---

no changes in v7

changes in v6:
- commit description change

new in v5
---
 kernel/bpf/syscall.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 83c7136c5788..776c7a37c433 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1437,9 +1437,9 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr)
 
 #define BPF_MAP_DELETE_ELEM_LAST_FIELD key
 
-static int map_delete_elem(union bpf_attr *attr)
+static int map_delete_elem(union bpf_attr *attr, bpfptr_t uattr)
 {
-	void __user *ukey = u64_to_user_ptr(attr->key);
+	bpfptr_t ukey = make_bpfptr(attr->key, uattr.is_kernel);
 	int ufd = attr->map_fd;
 	struct bpf_map *map;
 	struct fd f;
@@ -1459,7 +1459,7 @@ static int map_delete_elem(union bpf_attr *attr)
 		goto err_put;
 	}
 
-	key = __bpf_copy_key(ukey, map->key_size);
+	key = ___bpf_copy_key(ukey, map->key_size);
 	if (IS_ERR(key)) {
 		err = PTR_ERR(key);
 		goto err_put;
@@ -4942,7 +4942,7 @@ static int __sys_bpf(int cmd, bpfptr_t uattr, unsigned int size)
 		err = map_update_elem(&attr, uattr);
 		break;
 	case BPF_MAP_DELETE_ELEM:
-		err = map_delete_elem(&attr);
+		err = map_delete_elem(&attr, uattr);
 		break;
 	case BPF_MAP_GET_NEXT_KEY:
 		err = map_get_next_key(&attr);
@@ -5077,8 +5077,10 @@ BPF_CALL_3(bpf_sys_bpf, int, cmd, union bpf_attr *, attr, u32, attr_size)
 
 	switch (cmd) {
 	case BPF_MAP_CREATE:
+	case BPF_MAP_DELETE_ELEM:
 	case BPF_MAP_UPDATE_ELEM:
 	case BPF_MAP_FREEZE:
+	case BPF_MAP_GET_FD_BY_ID:
 	case BPF_PROG_LOAD:
 	case BPF_BTF_LOAD:
 	case BPF_LINK_CREATE:
-- 
2.36.1