From: Alexei Starovoitov ast@kernel.org
mainline inclusion from mainline-5.14-rc1 commit 3abea089246f76c1517b054ddb5946f3f1dbd2c0 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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... (cherry picked from commit 3abea089246f76c1517b054ddb5946f3f1dbd2c0) Signed-off-by: Wang Yufen wangyufen@huawei.com --- include/uapi/linux/bpf.h | 7 +++++++ kernel/bpf/syscall.c | 19 +++++++++++++++++++ tools/include/uapi/linux/bpf.h | 7 +++++++ 3 files changed, 33 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 0e88c9c8552e..d8fc4d8c7bc5 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3892,6 +3892,12 @@ union bpf_attr { * Find BTF type with given name and kind in vmlinux BTF or in module's BTFs. * Return * Returns btf_id and btf_obj_fd in lower and upper 32 bits. + * + * long bpf_sys_close(u32 fd) + * Description + * Execute close syscall for given FD. + * Return + * A syscall result. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -4059,6 +4065,7 @@ union bpf_attr { FN(snprintf), \ 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 a9c1fa6d05a7..b916a6438d7d 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -4665,6 +4665,23 @@ 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(current->files, 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) { @@ -4673,6 +4690,8 @@ 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); } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index f9d82a60d26b..dde6a6042d32 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -4602,6 +4602,12 @@ union bpf_attr { * Find BTF type with given name and kind in vmlinux BTF or in module's BTFs. * Return * Returns btf_id and btf_obj_fd in lower and upper 32 bits. + * + * long bpf_sys_close(u32 fd) + * Description + * Execute close syscall for given FD. + * Return + * A syscall result. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -4769,6 +4775,7 @@ union bpf_attr { FN(snprintf), \ FN(sys_bpf), \ FN(btf_find_by_name_kind), \ + FN(sys_close), \ /* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper