[PATCH bpf-next 11/15] bpf: Add bpf_sys_close() helper.

[Alexei Starovoitov]

From: Alexei Starovoitov <a...@kernel.org>

Add bpf_sys_close() helper to be used by the syscall/loader program to close
intermediate FDs and other cleanup.

Signed-off-by: Alexei Starovoitov <a...@kernel.org>
---
 include/uapi/linux/bpf.h       |  7 +++++++
 kernel/bpf/syscall.c           | 14 ++++++++++++++
 tools/include/uapi/linux/bpf.h |  7 +++++++
 3 files changed, 28 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 47c4b21a51b6..2251e7894799 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4728,6 +4728,12 @@ union bpf_attr {
  *             If btf_fd is zero look for the name in vmlinux BTF and kernel 
module BTFs.
  *     Return
  *             Return btf_id and store module's BTF FD into attach_btf_obj_fd.
+ *
+ * long bpf_sys_close(u32 fd)
+ *     Description
+ *             Execute close syscall for given FD.
+ *     Return
+ *             A syscall result.
  */
 #define __BPF_FUNC_MAPPER(FN)          \
        FN(unspec),                     \
@@ -4897,6 +4903,7 @@ union bpf_attr {
        FN(for_each_map_elem),          \
        FN(sys_bpf),                    \
        FN(btf_find_by_name_kind),      \
+       FN(sys_close),                  \
        /* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 6d4d9925c0ec..822b00908c58 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4557,6 +4557,18 @@ const struct bpf_func_proto bpf_sys_bpf_proto = {
        .arg3_type      = ARG_CONST_SIZE,
 };
 
+BPF_CALL_1(bpf_sys_close, u32, fd)
+{
+       return close_fd(fd);
+}
+
+const struct bpf_func_proto bpf_sys_close_proto = {
+       .func           = bpf_sys_close,
+       .gpl_only       = false,
+       .ret_type       = RET_INTEGER,
+       .arg1_type      = ARG_ANYTHING,
+};
+
 static const struct bpf_func_proto *
 syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
@@ -4565,6 +4577,8 @@ syscall_prog_func_proto(enum bpf_func_id func_id, const 
struct bpf_prog *prog)
                return &bpf_sys_bpf_proto;
        case BPF_FUNC_btf_find_by_name_kind:
                return &bpf_btf_find_by_name_kind_proto;
+       case BPF_FUNC_sys_close:
+               return &bpf_sys_close_proto;
        default:
                return bpf_base_func_proto(func_id);
        }
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 47c4b21a51b6..2251e7894799 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4728,6 +4728,12 @@ union bpf_attr {
  *             If btf_fd is zero look for the name in vmlinux BTF and kernel 
module BTFs.
  *     Return
  *             Return btf_id and store module's BTF FD into attach_btf_obj_fd.
+ *
+ * long bpf_sys_close(u32 fd)
+ *     Description
+ *             Execute close syscall for given FD.
+ *     Return
+ *             A syscall result.
  */
 #define __BPF_FUNC_MAPPER(FN)          \
        FN(unspec),                     \
@@ -4897,6 +4903,7 @@ union bpf_attr {
        FN(for_each_map_elem),          \
        FN(sys_bpf),                    \
        FN(btf_find_by_name_kind),      \
+       FN(sys_close),                  \
        /* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
-- 
2.30.2