This is a note to let you know that I've just added the patch titled
selftests/bpf: Add tests for _opts variants of bpf_*_get_fd_by_id()
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
selftests-bpf-add-tests-for-_opts-variants-of-bpf_-_.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0518935ec5cbf2164071978f6e007ec8a5bf27e7
Author: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Date: Thu Oct 6 13:07:36 2022 +0200
selftests/bpf: Add tests for _opts variants of bpf_*_get_fd_by_id()
[ Upstream commit a9c7c18b57594c72a63fad749021b743c65a098b ]
Introduce the data_input map, write-protected with a small eBPF program
implementing the lsm/bpf_map hook.
Then, ensure that bpf_map_get_fd_by_id() and bpf_map_get_fd_by_id_opts()
with NULL opts don't succeed due to requesting read-write access to the
write-protected map. Also, ensure that bpf_map_get_fd_by_id_opts() with
open_flags in opts set to BPF_F_RDONLY instead succeeds.
After obtaining a read-only fd, ensure that only map lookup succeeds and
not update. Ensure that update works only with the read-write fd obtained
at program loading time, when the write protection was not yet enabled.
Finally, ensure that the other _opts variants of bpf_*_get_fd_by_id() don't
work if the BPF_F_RDONLY flag is set in opts (due to the kernel not
handling the open_flags member of bpf_attr).
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20221006110736.84253-7-roberto.sassu@xxxxxxxxxxxxxxx
Stable-dep-of: aa8ebb270c66 ("selftests/bpf: Workaround strict bpf_lsm return value check.")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x
index 0fb03b8047d53..beef1232a47ae 100644
--- a/tools/testing/selftests/bpf/DENYLIST.s390x
+++ b/tools/testing/selftests/bpf/DENYLIST.s390x
@@ -76,3 +76,4 @@ lookup_key # JIT does not support calling kernel f
verify_pkcs7_sig # JIT does not support calling kernel function (kfunc)
kfunc_dynptr_param # JIT does not support calling kernel function (kfunc)
deny_namespace # failed to attach: ERROR: strerror_r(-524)=22 (trampoline)
+libbpf_get_fd_by_id_opts # failed to attach: ERROR: strerror_r(-524)=22 (trampoline)
diff --git a/tools/testing/selftests/bpf/prog_tests/libbpf_get_fd_by_id_opts.c b/tools/testing/selftests/bpf/prog_tests/libbpf_get_fd_by_id_opts.c
new file mode 100644
index 0000000000000..25e5dfa9c315c
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/libbpf_get_fd_by_id_opts.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
+ */
+
+#include <test_progs.h>
+
+#include "test_libbpf_get_fd_by_id_opts.skel.h"
+
+void test_libbpf_get_fd_by_id_opts(void)
+{
+ struct test_libbpf_get_fd_by_id_opts *skel;
+ struct bpf_map_info info_m = {};
+ __u32 len = sizeof(info_m), value;
+ int ret, zero = 0, fd = -1;
+ LIBBPF_OPTS(bpf_get_fd_by_id_opts, fd_opts_rdonly,
+ .open_flags = BPF_F_RDONLY,
+ );
+
+ skel = test_libbpf_get_fd_by_id_opts__open_and_load();
+ if (!ASSERT_OK_PTR(skel,
+ "test_libbpf_get_fd_by_id_opts__open_and_load"))
+ return;
+
+ ret = test_libbpf_get_fd_by_id_opts__attach(skel);
+ if (!ASSERT_OK(ret, "test_libbpf_get_fd_by_id_opts__attach"))
+ goto close_prog;
+
+ ret = bpf_obj_get_info_by_fd(bpf_map__fd(skel->maps.data_input),
+ &info_m, &len);
+ if (!ASSERT_OK(ret, "bpf_obj_get_info_by_fd"))
+ goto close_prog;
+
+ fd = bpf_map_get_fd_by_id(info_m.id);
+ if (!ASSERT_LT(fd, 0, "bpf_map_get_fd_by_id"))
+ goto close_prog;
+
+ fd = bpf_map_get_fd_by_id_opts(info_m.id, NULL);
+ if (!ASSERT_LT(fd, 0, "bpf_map_get_fd_by_id_opts"))
+ goto close_prog;
+
+ fd = bpf_map_get_fd_by_id_opts(info_m.id, &fd_opts_rdonly);
+ if (!ASSERT_GE(fd, 0, "bpf_map_get_fd_by_id_opts"))
+ goto close_prog;
+
+ /* Map lookup should work with read-only fd. */
+ ret = bpf_map_lookup_elem(fd, &zero, &value);
+ if (!ASSERT_OK(ret, "bpf_map_lookup_elem"))
+ goto close_prog;
+
+ if (!ASSERT_EQ(value, 0, "map value mismatch"))
+ goto close_prog;
+
+ /* Map update should not work with read-only fd. */
+ ret = bpf_map_update_elem(fd, &zero, &len, BPF_ANY);
+ if (!ASSERT_LT(ret, 0, "bpf_map_update_elem"))
+ goto close_prog;
+
+ /* Map update should work with read-write fd. */
+ ret = bpf_map_update_elem(bpf_map__fd(skel->maps.data_input), &zero,
+ &len, BPF_ANY);
+ if (!ASSERT_OK(ret, "bpf_map_update_elem"))
+ goto close_prog;
+
+ /* Prog get fd with opts set should not work (no kernel support). */
+ ret = bpf_prog_get_fd_by_id_opts(0, &fd_opts_rdonly);
+ if (!ASSERT_EQ(ret, -EINVAL, "bpf_prog_get_fd_by_id_opts"))
+ goto close_prog;
+
+ /* Link get fd with opts set should not work (no kernel support). */
+ ret = bpf_link_get_fd_by_id_opts(0, &fd_opts_rdonly);
+ if (!ASSERT_EQ(ret, -EINVAL, "bpf_link_get_fd_by_id_opts"))
+ goto close_prog;
+
+ /* BTF get fd with opts set should not work (no kernel support). */
+ ret = bpf_btf_get_fd_by_id_opts(0, &fd_opts_rdonly);
+ ASSERT_EQ(ret, -EINVAL, "bpf_btf_get_fd_by_id_opts");
+
+close_prog:
+ if (fd >= 0)
+ close(fd);
+
+ test_libbpf_get_fd_by_id_opts__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_libbpf_get_fd_by_id_opts.c b/tools/testing/selftests/bpf/progs/test_libbpf_get_fd_by_id_opts.c
new file mode 100644
index 0000000000000..f5ac5f3e89196
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_libbpf_get_fd_by_id_opts.c
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
+ */
+
+#include "vmlinux.h"
+#include <errno.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+/* From include/linux/mm.h. */
+#define FMODE_WRITE 0x2
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, __u32);
+} data_input SEC(".maps");
+
+char _license[] SEC("license") = "GPL";
+
+SEC("lsm/bpf_map")
+int BPF_PROG(check_access, struct bpf_map *map, fmode_t fmode)
+{
+ if (map != (struct bpf_map *)&data_input)
+ return 0;
+
+ if (fmode & FMODE_WRITE)
+ return -EACCES;
+
+ return 0;
+}
