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Date: Fri, 16 Aug 2024 12:12:13 -0700 Message-Id: <20240816191213.35573-7-thinker.li@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240816191213.35573-1-thinker.li@gmail.com> References: <20240816191213.35573-1-thinker.li@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net X-Patchwork-State: RFC Make sure the memory of uptrs have been mapped to the kernel properly. Also ensure the values of uptrs in the kernel haven't been copied to userspace. Signed-off-by: Kui-Feng Lee --- .../bpf/prog_tests/task_local_storage.c | 106 ++++++++++++++++++ .../selftests/bpf/progs/task_ls_uptr.c | 65 +++++++++++ 2 files changed, 171 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/task_ls_uptr.c diff --git a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c index c33c05161a9e..5709b083021c 100644 --- a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c +++ b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c @@ -5,6 +5,7 @@ #include #include #include +#include #include /* For SYS_xxx definitions */ #include #include @@ -14,6 +15,20 @@ #include "task_ls_recursion.skel.h" #include "task_storage_nodeadlock.skel.h" +struct user_data { + int a; + int b; + int result; +}; + +struct value_type { + struct user_data *udata; +}; + +#define MAGIC_VALUE 0xabcd1234 + +#include "task_ls_uptr.skel.h" + static void test_sys_enter_exit(void) { struct task_local_storage *skel; @@ -40,6 +55,95 @@ static void test_sys_enter_exit(void) task_local_storage__destroy(skel); } +static struct user_data user_data __attribute__((aligned(16))) = { + .a = 1, + .b = 2, +}; + +static void test_uptr(void) +{ + struct task_ls_uptr *skel = NULL; + int task_fd = -1, ev_fd = -1; + struct value_type value; + int err, wstatus; + __u64 dummy = 1; + pid_t pid; + + value.udata = &user_data; + + task_fd = sys_pidfd_open(getpid(), 0); + if (!ASSERT_NEQ(task_fd, -1, "sys_pidfd_open")) + goto out; + + ev_fd = eventfd(0, 0); + if (!ASSERT_NEQ(ev_fd, -1, "eventfd")) + goto out; + + skel = task_ls_uptr__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_open_and_load")) + goto out; + + err = bpf_map_update_elem(bpf_map__fd(skel->maps.datamap), &task_fd, &value, 0); + if (!ASSERT_OK(err, "update_datamap")) + exit(1); + + err = task_ls_uptr__attach(skel); + if (!ASSERT_OK(err, "skel_attach")) + goto out; + + fflush(stdout); + fflush(stderr); + + pid = fork(); + if (pid < 0) + goto out; + + /* Call syscall in the child process, but access the map value of + * the parent process in the BPF program to check if the user kptr + * is translated/mapped correctly. + */ + if (pid == 0) { + /* child */ + + /* Overwrite the user_data in the child process to check if + * the BPF program accesses the user_data of the parent. + */ + user_data.a = 0; + user_data.b = 0; + + /* Wait for the parent to set child_pid */ + read(ev_fd, &dummy, sizeof(dummy)); + + exit(0); + } + + skel->bss->parent_pid = syscall(SYS_gettid); + skel->bss->child_pid = pid; + + write(ev_fd, &dummy, sizeof(dummy)); + + err = waitpid(pid, &wstatus, 0); + ASSERT_EQ(err, pid, "waitpid"); + skel->bss->child_pid = 0; + + ASSERT_EQ(MAGIC_VALUE + user_data.a + user_data.b, + user_data.result, "result"); + + /* Check if user programs can access the value of user kptrs + * through bpf_map_lookup_elem(). Make sure the kernel value is not + * leaked. + */ + err = bpf_map_lookup_elem(bpf_map__fd(skel->maps.datamap), &task_fd, &value); + if (!ASSERT_OK(err, "bpf_map_lookup_elem")) + goto out; + ASSERT_EQ(value.udata, NULL, "lookup_udata"); + +out: + task_ls_uptr__destroy(skel); + close(ev_fd); + close(task_fd); +} + static void test_exit_creds(void) { struct task_local_storage_exit_creds *skel; @@ -237,4 +341,6 @@ void test_task_local_storage(void) test_recursion(); if (test__start_subtest("nodeadlock")) test_nodeadlock(); + if (test__start_subtest("uptr")) + test_uptr(); } diff --git a/tools/testing/selftests/bpf/progs/task_ls_uptr.c b/tools/testing/selftests/bpf/progs/task_ls_uptr.c new file mode 100644 index 000000000000..473e6890d522 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/task_ls_uptr.c @@ -0,0 +1,65 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */ + +#include "vmlinux.h" +#include +#include +#include "task_kfunc_common.h" + +char _license[] SEC("license") = "GPL"; + +struct user_data { + int a; + int b; + int result; +}; + +struct value_type { + struct user_data __uptr *udata; +}; + +struct { + __uint(type, BPF_MAP_TYPE_TASK_STORAGE); + __uint(map_flags, BPF_F_NO_PREALLOC); + __type(key, int); + __type(value, struct value_type); +} datamap SEC(".maps"); + +#define MAGIC_VALUE 0xabcd1234 + +/* This is a workaround to avoid clang generating a forward reference for + * struct user_data. This is a known issue and will be fixed in the future. + */ +struct user_data __dummy; + +pid_t child_pid = 0; +pid_t parent_pid = 0; + +SEC("tp_btf/sys_enter") +int BPF_PROG(on_enter, struct pt_regs *regs, long id) +{ + struct task_struct *task, *data_task; + struct value_type *ptr; + struct user_data *udata; + + task = bpf_get_current_task_btf(); + if (task->pid != child_pid) + return 0; + + data_task = bpf_task_from_pid(parent_pid); + if (!data_task) + return 0; + + ptr = bpf_task_storage_get(&datamap, data_task, 0, + BPF_LOCAL_STORAGE_GET_F_CREATE); + bpf_task_release(data_task); + if (!ptr) + return 0; + + udata = ptr->udata; + if (!udata) + return 0; + udata->result = MAGIC_VALUE + udata->a + udata->b; + + return 0; +}