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authorAlexei Starovoitov <ast@kernel.org>2021-05-13 17:36:12 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2021-05-19 00:33:40 +0200
commit3abea089246f76c1517b054ddb5946f3f1dbd2c0 (patch)
tree7811366681e39789541fac724f153be78b6427c1 /kernel
parent3d78417b60fba249cc555468cb72d96f5cde2964 (diff)
downloadlinux-3abea089246f76c1517b054ddb5946f3f1dbd2c0.tar.bz2
bpf: Add bpf_sys_close() helper.
Add bpf_sys_close() helper to be used by the syscall/loader program to close intermediate FDs and other cleanup. Note this helper must never be allowed inside fdget/fdput bracketing. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210514003623.28033-11-alexei.starovoitov@gmail.com
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/syscall.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index f93ff2ebf96d..0f1ce2171f1e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4578,6 +4578,23 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return bpf_base_func_proto(func_id);
}
+BPF_CALL_1(bpf_sys_close, u32, fd)
+{
+ /* When bpf program calls this helper there should not be
+ * an fdget() without matching completed fdput().
+ * This helper is allowed in the following callchain only:
+ * sys_bpf->prog_test_run->bpf_prog->bpf_sys_close
+ */
+ 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)
{
@@ -4586,6 +4603,8 @@ 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 tracing_prog_func_proto(func_id, prog);
}