6.1-stable review patch. If anyone has any objections, please let me know.
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From: Roberto Sassu roberto.sassu@huawei.com
[ 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@huawei.com Signed-off-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20221006110736.84253-7-roberto.sassu@huaweicloud... Stable-dep-of: aa8ebb270c66 ("selftests/bpf: Workaround strict bpf_lsm return value check.") Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/bpf/DENYLIST.s390x | 1 + .../bpf/prog_tests/libbpf_get_fd_by_id_opts.c | 87 +++++++++++++++++++ .../bpf/progs/test_libbpf_get_fd_by_id_opts.c | 36 ++++++++ 3 files changed, 124 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/libbpf_get_fd_by_id_opts.c create mode 100644 tools/testing/selftests/bpf/progs/test_libbpf_get_fd_by_id_opts.c
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@huawei.com + */ + +#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@huawei.com + */ + +#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; +}