// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
#define _GNU_SOURCE
#include <test_progs.h>
#include <bpf/btf.h>
#include "cap_helpers.h"
#include <fcntl.h>
#include <sched.h>
#include <signal.h>
#include <unistd.h>
#include <linux/filter.h>
#include <linux/unistd.h>
#include <linux/mount.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/un.h>
#include "priv_map.skel.h"
#include "priv_prog.skel.h"
#include "dummy_st_ops_success.skel.h"
#include "token_lsm.skel.h"
static inline int sys_mount(const char *dev_name, const char *dir_name,
const char *type, unsigned long flags,
const void *data)
{
return syscall(__NR_mount, dev_name, dir_name, type, flags, data);
}
static inline int sys_fsopen(const char *fsname, unsigned flags)
{
return syscall(__NR_fsopen, fsname, flags);
}
static inline int sys_fspick(int dfd, const char *path, unsigned flags)
{
return syscall(__NR_fspick, dfd, path, flags);
}
static inline int sys_fsconfig(int fs_fd, unsigned cmd, const char *key, const void *val, int aux)
{
return syscall(__NR_fsconfig, fs_fd, cmd, key, val, aux);
}
static inline int sys_fsmount(int fs_fd, unsigned flags, unsigned ms_flags)
{
return syscall(__NR_fsmount, fs_fd, flags, ms_flags);
}
static inline int sys_move_mount(int from_dfd, const char *from_path,
int to_dfd, const char *to_path,
unsigned flags)
{
return syscall(__NR_move_mount, from_dfd, from_path, to_dfd, to_path, flags);
}
static int drop_priv_caps(__u64 *old_caps)
{
return cap_disable_effective((1ULL << CAP_BPF) |
(1ULL << CAP_PERFMON) |
(1ULL << CAP_NET_ADMIN) |
(1ULL << CAP_SYS_ADMIN), old_caps);
}
static int restore_priv_caps(__u64 old_caps)
{
return cap_enable_effective(old_caps, NULL);
}
static int set_delegate_mask(int fs_fd, const char *key, __u64 mask, const char *mask_str)
{
char buf[32];
int err;
if (!mask_str) {
if (mask == ~0ULL) {
mask_str = "any";
} else {
snprintf(buf, sizeof(buf), "0x%llx", (unsigned long long)mask);
mask_str = buf;
}
}
err = sys_fsconfig(fs_fd, FSCONFIG_SET_STRING, key,
mask_str, 0);
if (err < 0)
err = -errno;
return err;
}
#define zclose(fd) do { if (fd >= 0) close(fd); fd = -1; } while (0)
struct bpffs_opts {
__u64 cmds;
__u64 maps;
__u64 progs;
__u64 attachs;
const char *cmds_str;
const char *maps_str;
const char *progs_str;
const char *attachs_str;
};
static int create_bpffs_fd(void)
{
int fs_fd;
/* create VFS context */
fs_fd = sys_fsopen("bpf", 0);
ASSERT_GE(fs_fd, 0, "fs_fd");
return fs_fd;
}
static int materialize_bpffs_fd(int fs_fd, struct bpffs_opts *opts)
{
int mnt_fd, err;
/* set up token delegation mount options */
err = set_delegate_mask(fs_fd, "delegate_cmds", opts->cmds, opts->cmds_str);
if (!ASSERT_OK(err, "fs_cfg_cmds"))
return err;
err = set_delegate_mask(fs_fd, "delegate_maps", opts->maps, opts->maps_str);
if (!ASSERT_OK(err, "fs_cfg_maps"))
return err;
err = set_delegate_mask(fs_fd, "delegate_progs", opts->progs, opts->progs_str);
if (!ASSERT_OK(err, "fs_cfg_progs"))
return err;
err = set_delegate_mask(fs_fd, "delegate_attachs", opts->attachs, opts->attachs_str);
if (!ASSERT_OK(err, "fs_cfg_attachs"))
return err;
/* instantiate FS object */
err = sys_fsconfig(fs_fd, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
if (err < 0)
return -errno;
/* create O_PATH fd for detached mount */
mnt_fd = sys_fsmount(fs_fd, 0, 0);
if (err < 0)
return -errno;
return mnt_fd;
}
/* send FD over Unix domain (AF_UNIX) socket */
static int sendfd(int sockfd, int fd)
{
struct msghdr msg = {};
struct cmsghdr *cmsg;
int fds[1] = { fd }, err;
char iobuf[1];
struct iovec io = {
.iov_base = iobuf,
.iov_len = sizeof(iobuf),
};
union {
char buf[CMSG_SPACE(sizeof(fds))];
struct cmsghdr align;
} u;
msg.msg_iov = &io;
msg.msg_iovlen = 1;
msg.msg_control = u.buf;
msg.msg_controllen = sizeof(u.buf);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(fds));
memcpy(CMSG_DATA(cmsg), fds, sizeof(fds));
err = sendmsg(sockfd, &msg, 0);
if (err < 0)
err = -errno;
if (!ASSERT_EQ(err, 1, "sendmsg"))
return -EINVAL;
return 0;
}
/* receive FD over Unix domain (AF_UNIX) socket */
static int recvfd(int sockfd, int *fd)
{
struct msghdr msg = {};
struct cmsghdr *cmsg;
int fds[1], err;
char iobuf[1];
struct iovec io = {
.iov_base = iobuf,
.iov_len = sizeof(iobuf),
};
union {
char buf[CMSG_SPACE(sizeof(fds))];
struct cmsghdr align;
} u;
msg.msg_iov = &io;
msg.msg_iovlen = 1;
msg.msg_control = u.buf;
msg.msg_controllen = sizeof(u.buf);
err = recvmsg(sockfd, &msg, 0);
if (err < 0)
err = -errno;
if (!ASSERT_EQ(err, 1, "recvmsg"))
return -EINVAL;
cmsg = CMSG_FIRSTHDR(&msg);
if (!ASSERT_OK_PTR(cmsg, "cmsg_null") ||
!ASSERT_EQ(cmsg->cmsg_len, CMSG_LEN(sizeof(fds)), "cmsg_len") ||
!ASSERT_EQ(cmsg->cmsg_level, SOL_SOCKET, "cmsg_level") ||
!ASSERT_EQ(cmsg->cmsg_type, SCM_RIGHTS, "cmsg_type"))
return -EINVAL;
memcpy(fds, CMSG_DATA(cmsg), sizeof(fds));
*fd = fds[0];
return 0;
}
static ssize_t write_nointr(int fd, const void *buf, size_t count)
{
ssize_t ret;
do {
ret = write(fd, buf, count);
} while (ret < 0 && errno == EINTR);
return ret;
}
static int write_file(const char *path, const void *buf, size_t count)
{
int fd;
ssize_t ret;
fd = open(path, O_WRONLY | O_CLOEXEC | O_NOCTTY | O_NOFOLLOW);
if (fd < 0)
return -1;
ret = write_nointr(fd, buf, count);
close(fd);
if (ret < 0 || (size_t)ret != count)
return -1;
return 0;
}
static int create_and_enter_userns(void)
{
uid_t uid;
gid_t gid;
char map[100];
uid = getuid();
gid = getgid();
if (unshare(CLONE_NEWUSER))
return -1;
if (write_file("/proc/self/setgroups", "deny", sizeof("deny") - 1) &&
errno != ENOENT)
return -1;
snprintf(map, sizeof(map), "0 %d 1", uid);
if (write_file("/proc/self/uid_map", map, strlen(map)))
return -1;
snprintf(map, sizeof(map), "0 %d 1", gid);
if (write_file("/proc/self/gid_map", map, strlen(map)))
return -1;
if (setgid(0))
return -1;
if (setuid(0))
return -1;
return 0;
}
typedef int (*child_callback_fn)(int bpffs_fd, struct token_lsm *lsm_skel);
static void child(int sock_fd, struct bpffs_opts *opts, child_callback_fn callback)
{
int mnt_fd = -1, fs_fd = -1, err = 0, bpffs_fd = -1, token_fd = -1;
struct token_lsm *lsm_skel = NULL;
/* load and attach LSM "policy" before we go into unpriv userns */
lsm_skel = token_lsm__open_and_load();
if (!ASSERT_OK_PTR(lsm_skel, "lsm_skel_load")) {
err = -EINVAL;
goto cleanup;
}
lsm_skel->bss->my_pid = getpid();
err = token_lsm__attach(lsm_skel);
if (!ASSERT_OK(err, "lsm_skel_attach"))
goto cleanup;
/* setup userns with root mappings */
err = create_and_enter_userns();
if (!ASSERT_OK(err, "create_and_enter_userns"))
goto cleanup;
/* setup mountns to allow creating BPF FS (fsopen("bpf")) from unpriv process */
err = unshare(CLONE_NEWNS);
if (!ASSERT_OK(err, "create_mountns"))
goto cleanup;
err = sys_mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
if (!ASSERT_OK(err, "remount_root"))
goto cleanup;
fs_fd = create_bpffs_fd();
if (!ASSERT_GE(fs_fd, 0, "create_bpffs_fd")) {
err = -EINVAL;
goto cleanup;
}
/* ensure unprivileged child cannot set delegation options */
err = set_delegate_mask(fs_fd, "delegate_cmds", 0x1, NULL);
ASSERT_EQ(err, -EPERM, "delegate_cmd_eperm");
err = set_delegate_mask(fs_fd, "delegate_maps", 0x1, NULL);
ASSERT_EQ(err, -EPERM, "delegate_maps_eperm");
err = set_delegate_mask(fs_fd, "delegate_progs", 0x1, NULL);
ASSERT_EQ(err, -EPERM, "delegate_progs_eperm");
err = set_delegate_mask(fs_fd, "delegate_attachs", 0x1, NULL);
ASSERT_EQ(err, -EPERM, "delegate_attachs_eperm");
/* pass BPF FS context object to parent */
err = sendfd(sock_fd, fs_fd);
if (!ASSERT_OK(err, "send_fs_fd"))
goto cleanup;
zclose(fs_fd);
/* avoid mucking around with mount namespaces and mounting at
* well-known path, just get detach-mounted BPF FS fd back from parent
*/
err = recvfd(sock_fd, &mnt_fd);
if (!ASSERT_OK(err, "recv_mnt_fd"))
goto cleanup;
/* try to fspick() BPF FS and try to add some delegation options */
fs_fd = sys_fspick(mnt_fd, "", FSPICK_EMPTY_PATH);
if (!ASSERT_GE(fs_fd, 0, "bpffs_fspick")) {
err = -EINVAL;
goto cleanup;
}
/* ensure unprivileged child cannot reconfigure to set delegation options */
err = set_delegate_mask(fs_fd, "delegate_cmds", 0, "any");
if (!ASSERT_EQ(err, -EPERM, "delegate_cmd_eperm_reconfig")) {
err = -EINVAL;
goto cleanup;
}
err = set_delegate_mask(fs_fd, "delegate_maps", 0, "any");
if (!ASSERT_EQ(err, -EPERM, "delegate_maps_eperm_reconfig")) {
err = -EINVAL;
goto cleanup;
}
err = set_delegate_mask(fs_fd, "delegate_progs", 0, "any");
if (!ASSERT_EQ(err, -EPERM, "delegate_progs_eperm_reconfig")) {
err = -EINVAL;
goto cleanup;
}
err = set_delegate_mask(fs_fd, "delegate_attachs", 0, "any");
if (!ASSERT_EQ(err, -EPERM, "delegate_attachs_eperm_reconfig")) {
err = -EINVAL;
goto cleanup;
}
zclose(fs_fd);
bpffs_fd = openat(mnt_fd, ".", 0, O_RDWR);
if (!ASSERT_GE(bpffs_fd, 0, "bpffs_open")) {
err = -EINVAL;
goto cleanup;
}
/* create BPF token FD and pass it to parent for some extra checks */
token_fd = bpf_token_create(bpffs_fd, NULL);
if (!ASSERT_GT(token_fd, 0, "child_token_create")) {
err = -EINVAL;
goto cleanup;
}
err = sendfd(sock_fd, token_fd);
if (!ASSERT_OK(err, "send_token_fd"))
goto cleanup;
zclose(token_fd);
/* do custom test logic with customly set up BPF FS instance */
err = callback(bpffs_fd, lsm_skel);
if (!ASSERT_OK(err, "test_callback"))
goto cleanup;
err = 0;
cleanup:
zclose(sock_fd);
zclose(mnt_fd);
zclose(fs_fd);
zclose(bpffs_fd);
zclose(token_fd);
lsm_skel->bss->my_pid = 0;
token_lsm__destroy(lsm_skel);
exit(-err);
}
static int wait_for_pid(pid_t pid)
{
int status, ret;
again:
ret = waitpid(pid, &status, 0);
if (ret == -1) {
if (errno == EINTR)
goto again;
return -1;
}
if (!WIFEXITED(status))
return -1;
return WEXITSTATUS(status);
}
static void parent(int child_pid, struct bpffs_opts *bpffs_opts, int sock_fd)
{
int fs_fd = -1, mnt_fd = -1, token_fd = -1, err;
err = recvfd(sock_fd, &fs_fd);
if (!ASSERT_OK(err, "recv_bpffs_fd"))
goto cleanup;
mnt_fd = materialize_bpffs_fd(fs_fd, bpffs_opts);
if (!ASSERT_GE(mnt_fd, 0, "materialize_bpffs_fd")) {
err = -EINVAL;
goto cleanup;
}
zclose(fs_fd);
/* pass BPF FS context object to parent */
err = sendfd(sock_fd, mnt_fd);
if (!ASSERT_OK(err, "send_mnt_fd"))
goto cleanup;
zclose(mnt_fd);
/* receive BPF token FD back from child for some extra tests */
err = recvfd(sock_fd, &token_fd);
if (!ASSERT_OK(err, "recv_token_fd"))
goto cleanup;
err = wait_for_pid(child_pid);
ASSERT_OK(err, "waitpid_child");
cleanup:
zclose(sock_fd);
zclose(fs_fd);
zclose(mnt_fd);
zclose(token_fd);
if (child_pid > 0)
(void)kill(child_pid, SIGKILL);
}
static void subtest_userns(struct bpffs_opts *bpffs_opts,
child_callback_fn child_cb)
{
int sock_fds[2] = { -1, -1 };
int child_pid = 0, err;
err = socketpair(AF_UNIX, SOCK_STREAM, 0, sock_fds);
if (!ASSERT_OK(err, "socketpair"))
goto cleanup;
child_pid = fork();
if (!ASSERT_GE(child_pid, 0, "fork"))
goto cleanup;
if (child_pid == 0) {
zclose(sock_fds[0]);
return child(sock_fds[1], bpffs_opts, child_cb);
} else {
zclose(sock_fds[1]);
return parent(child_pid, bpffs_opts, sock_fds[0]);
}
cleanup:
zclose(sock_fds[0]);
zclose(sock_fds[1]);
if (child_pid > 0)
(void)kill(child_pid, SIGKILL);
}
static int userns_map_create(int mnt_fd, struct token_lsm *lsm_skel)
{
LIBBPF_OPTS(bpf_map_create_opts, map_opts);
int err, token_fd = -1, map_fd = -1;
__u64 old_caps = 0;
/* create BPF token from BPF FS mount */
token_fd = bpf_token_create(mnt_fd, NULL);
if (!ASSERT_GT(token_fd, 0, "token_create")) {
err = -EINVAL;
goto cleanup;
}
/* while inside non-init userns, we need both a BPF token *and*
* CAP_BPF inside current userns to create privileged map; let's test
* that neither BPF token alone nor namespaced CAP_BPF is sufficient
*/
err = drop_priv_caps(&old_caps);
if (!ASSERT_OK(err, "drop_caps"))
goto cleanup;
/* no token, no CAP_BPF -> fail */
map_opts.map_flags = 0;
map_opts.token_fd = 0;
map_fd = bpf_map_create(BPF_MAP_TYPE_STACK, "wo_token_wo_bpf", 0, 8, 1, &map_opts);
if (!ASSERT_LT(map_fd, 0, "stack_map_wo_token_wo_cap_bpf_should_fail")) {
err = -EINVAL;
goto cleanup;
}
/* token without CAP_BPF -> fail */
map_opts.map_flags = BPF_F_TOKEN_FD;
map_opts.token_fd = token_fd;
map_fd = bpf_map_create(BPF_MAP_TYPE_STACK, "w_token_wo_bpf", 0, 8, 1, &map_opts);
if (!ASSERT_LT(map_fd, 0, "stack_map_w_token_wo_cap_bpf_should_fail")) {
err = -EINVAL;
goto cleanup;
}
/* get back effective local CAP_BPF (and CAP_SYS_ADMIN) */
err = restore_priv_caps(old_caps);
if (!ASSERT_OK(err, "restore_caps"))
goto cleanup;
/* CAP_BPF without token -> fail */
map_opts.map_flags = 0;
map_opts.token_fd = 0;
map_fd = bpf_map_create(BPF_MAP_TYPE_STACK, "wo_token_w_bpf", 0, 8, 1, &map_opts);
if (!ASSERT_LT(map_fd, 0, "stack_map_wo_token_w_cap_bpf_should_fail")) {
err = -EINVAL;
goto cleanup;
}
/* finally, namespaced CAP_BPF + token -> success */
map_opts.map_flags = BPF_F_TOKEN_FD;
map_opts.token_fd = token_fd;
map_fd = bpf_map_create(BPF_MAP_TYPE_STACK, "w_token_w_bpf", 0, 8, 1, &map_opts);
if (!ASSERT_GT(map_fd, 0, "stack_map_w_token_w_cap_bpf")) {
err = -EINVAL;
goto cleanup;
}
cleanup:
zclose(token_fd);
zclose(map_fd);
return err;
}
static int userns_btf_load(int mnt_fd, struct token_lsm *lsm_skel)
{
LIBBPF_OPTS(bpf_btf_load_opts, btf_opts);
int err, token_fd = -1, btf_fd = -1;
const void *raw_btf_data;
struct btf *btf = NULL;
__u32 raw_btf_size;
__u64 old_caps = 0;
/* create BPF token from BPF FS mount */
token_fd = bpf_token_create(mnt_fd, NULL);
if (!ASSERT_GT(token_fd, 0, "token_create")) {
err = -EINVAL;
goto cleanup;
}
/* while inside non-init userns, we need both a BPF token *and*
* CAP_BPF inside current userns to create privileged map; let's test
* that neither BPF token alone nor namespaced CAP_BPF is sufficient
*/
err = drop_priv_caps(&old_caps);
if (!ASSERT_OK(err, "drop_caps"))
goto cleanup;
/* setup a trivial BTF data to load to the kernel */
btf = btf__new_empty();
if (!ASSERT_OK_PTR(btf, "empty_btf"))
goto cleanup;
ASSERT_GT(btf__add_int(btf, "int", 4, 0), 0, "int_type");
raw_btf_data = btf__raw_data(btf, &raw_btf_size);
if (!ASSERT_OK_PTR(raw_btf_data, "raw_btf_data"))
goto cleanup;
/* no token + no CAP_BPF -> failure */
btf_opts.btf_flags = 0;
btf_opts.token_fd = 0;
btf_fd = bpf_btf_load(raw_btf_data, raw_btf_size, &btf_opts);
if (!ASSERT_LT(btf_fd, 0, "no_token_no_cap_should_fail"))
goto cleanup;
/* token + no CAP_BPF -> failure */
btf_opts.btf_flags = BPF_F_TOKEN_FD;
btf_opts.token_fd = token_fd;
btf_fd = bpf_btf_load(raw_btf_data, raw_btf_size, &btf_opts);
if (!ASSERT_LT(btf_fd, 0, "token_no_cap_should_fail"))
goto cleanup;
/* get back effective local CAP_BPF (and CAP_SYS_ADMIN) */
err = restore_priv_caps(old_caps);
if (!ASSERT_OK(err, "restore_caps"))
goto cleanup;
/* token + CAP_BPF -> success */
btf_opts.btf_flags = BPF_F_TOKEN_FD;
btf_opts.token_fd = token_fd;
btf_fd = bpf_btf_load(raw_btf_data, raw_btf_size, &btf_opts);
if (!ASSERT_GT(btf_fd, 0, "token_and_cap_success"))
goto cleanup;
err = 0;
cleanup:
btf__free(btf);
zclose(btf_fd);
zclose(token_fd);
return err;
}
static int userns_prog_load(int mnt_fd, struct token_lsm *lsm_skel)
{
LIBBPF_OPTS(bpf_prog_load_opts, prog_opts);
int err, token_fd = -1, prog_fd = -1;
struct bpf_insn insns[] = {
/* bpf_jiffies64() requires CAP_BPF */
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_jiffies64),
/* bpf_get_current_task() requires CAP_PERFMON */
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_current_task),
/* r0 = 0; exit; */
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
};
size_t insn_cnt = ARRAY_SIZE(insns);
__u64 old_caps = 0;
/* create BPF token from BPF FS mount */
token_fd = bpf_token_create(mnt_fd, NULL);
if (!ASSERT_GT(token_fd, 0, "token_create")) {
err = -EINVAL;
goto cleanup;
}
/* validate we can successfully load BPF program with token; this
* being XDP program (CAP_NET_ADMIN) using bpf_jiffies64() (CAP_BPF)
* and bpf_get_current_task() (CAP_PERFMON) helpers validates we have
* BPF token wired properly in a bunch of places in the kernel
*/
prog_opts.prog_flags = BPF_F_TOKEN_FD;
prog_opts.token_fd = token_fd;
prog_opts.expected_attach_type = BPF_XDP;
prog_fd = bpf_prog_load(BPF_PROG_TYPE_XDP, "token_prog", "GPL",
insns, insn_cnt, &prog_opts);
if (!ASSERT_GT(prog_fd, 0, "prog_fd")) {
err = -EPERM;
goto cleanup;
}
/* no token + caps -> failure */
prog_opts.prog_flags = 0;
prog_opts.token_fd = 0;
prog_fd = bpf_prog_load(BPF_PROG_TYPE_XDP, "token_prog", "GPL",
insns, insn_cnt, &prog_opts);
if (!ASSERT_EQ(prog_fd, -EPERM, "prog_fd_eperm")) {
err = -EPERM;
goto cleanup;
}
err = drop_priv_caps(&old_caps);
if (!ASSERT_OK(err, "drop_caps"))
goto cleanup;
/* no caps + token -> failure */
prog_opts.prog_flags = BPF_F_TOKEN_FD;
prog_opts.token_fd = token_fd;
prog_fd = bpf_prog_load(BPF_PROG_TYPE_XDP, "token_prog", "GPL",
insns, insn_cnt, &prog_opts);
if (!ASSERT_EQ(prog_fd, -EPERM, "prog_fd_eperm")) {
err = -EPERM;
goto cleanup;
}
/* no caps + no token -> definitely a failure */
prog_opts.prog_flags = 0;
prog_opts.token_fd = 0;
prog_fd = bpf_prog_load(BPF_PROG_TYPE_XDP, "token_prog", "GPL",
insns, insn_cnt, &prog_opts);
if (!ASSERT_EQ(prog_fd, -EPERM, "prog_fd_eperm")) {
err = -EPERM;
goto cleanup;
}
err = 0;
cleanup:
zclose(prog_fd);
zclose(token_fd);
return err;
}
static int userns_obj_priv_map(int mnt_fd, struct token_lsm *lsm_skel)
{
LIBBPF_OPTS(bpf_object_open_opts, opts);
char buf[256];
struct priv_map *skel;
int err;
skel = priv_map__open_and_load();
if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load")) {
priv_map__destroy(skel);
return -EINVAL;
}
/* use bpf_token_path to provide BPF FS path */
snprintf(buf, sizeof(buf), "/proc/self/fd/%d", mnt_fd);
opts.bpf_token_path = buf;
skel = priv_map__open_opts(&opts);
if (!ASSERT_OK_PTR(skel, "obj_token_path_open"))
return -EINVAL;
err = priv_map__load(skel);
priv_map__destroy(skel);
if (!ASSERT_OK(err, "obj_token_path_load"))
return -EINVAL;
return 0;
}
static int userns_obj_priv_prog(int mnt_fd, struct token_lsm *lsm_skel)
{
LIBBPF_OPTS(bpf_object_open_opts, opts);
char buf[256];
struct priv_prog *skel;
int err;
skel = priv_prog__open_and_load();
if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load")) {
priv_prog__destroy(skel);
return -EINVAL;
}
/* use bpf_token_path to provide BPF FS path */
snprintf(buf, sizeof(buf), "/proc/self/fd/%d", mnt_fd);
opts.bpf_token_path = buf;
skel = priv_prog__open_opts(&opts);
if (!ASSERT_OK_PTR(skel, "obj_token_path_open"))
return -EINVAL;
err = priv_prog__load(skel);
priv_prog__destroy(skel);
if (!ASSERT_OK(err, "obj_token_path_load"))
return -EINVAL;
/* provide BPF token, but reject bpf_token_capable() with LSM */
lsm_skel->bss->reject_capable = true;
lsm_skel->bss->reject_cmd = false;
skel = priv_prog__open_opts(&opts);
if (!ASSERT_OK_PTR(skel, "obj_token_lsm_reject_cap_open"))
return -EINVAL;
err = priv_prog__load(skel);
priv_prog__destroy(skel);
if (!ASSERT_ERR(err, "obj_token_lsm_reject_cap_load"))
return -EINVAL;
/* provide BPF token, but reject bpf_token_cmd() with LSM */
lsm_skel->bss->reject_capable = false;
lsm_skel->bss->reject_cmd = true;
skel = priv_prog__open_opts(&opts);
if (!ASSERT_OK_PTR(skel, "obj_token_lsm_reject_cmd_open"))
return -EINVAL;
err = priv_prog__load(skel);
priv_prog__destroy(skel);
if (!ASSERT_ERR(err, "obj_token_lsm_reject_cmd_load"))
return -EINVAL;
return 0;
}
/* this test is called with BPF FS that doesn't delegate BPF_BTF_LOAD command,
* which should cause struct_ops application to fail, as BTF won't be uploaded
* into the kernel, even if STRUCT_OPS programs themselves are allowed
*/
static int validate_struct_ops_load(int mnt_fd, bool expect_success)
{
LIBBPF_OPTS(bpf_object_open_opts, opts);
char buf[256];
struct dummy_st_ops_success *skel;
int err;
snprintf(buf, sizeof(buf), "/proc/self/fd/%d", mnt_fd);
opts.bpf_token_path = buf;
skel = dummy_st_ops_success__open_opts(&opts);
if (!ASSERT_OK_PTR(skel, "obj_token_path_open"))
return -EINVAL;
err = dummy_st_ops_success__load(skel);
dummy_st_ops_success__destroy(skel);
if (expect_success) {
if (!ASSERT_OK(err, "obj_token_path_load"))
return -EINVAL;
} else /* expect failure */ {
if (!ASSERT_ERR(err, "obj_token_path_load"))
return -EINVAL;
}
return 0;
}
static int userns_obj_priv_btf_fail(int mnt_fd, struct token_lsm *lsm_skel)
{
return validate_struct_ops_load(mnt_fd, false /* should fail */);
}
static int userns_obj_priv_btf_success(int mnt_fd, struct token_lsm *lsm_skel)
{
return validate_struct_ops_load(mnt_fd, true /* should succeed */);
}
#define TOKEN_ENVVAR "LIBBPF_BPF_TOKEN_PATH"
#define TOKEN_BPFFS_CUSTOM "/bpf-token-fs"
static int userns_obj_priv_implicit_token(int mnt_fd, struct token_lsm *lsm_skel)
{
LIBBPF_OPTS(bpf_object_open_opts, opts);
struct dummy_st_ops_success *skel;
int err;
/* before we mount BPF FS with token delegation, struct_ops skeleton
* should fail to load
*/
skel = dummy_st_ops_success__open_and_load();
if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load")) {
dummy_st_ops_success__destroy(skel);
return -EINVAL;
}
/* mount custom BPF FS over /sys/fs/bpf so that libbpf can create BPF
* token automatically and implicitly
*/
err = sys_move_mount(mnt_fd, "", AT_FDCWD, "/sys/fs/bpf", MOVE_MOUNT_F_EMPTY_PATH);
if (!ASSERT_OK(err, "move_mount_bpffs"))
return -EINVAL;
/* disable implicit BPF token creation by setting
* LIBBPF_BPF_TOKEN_PATH envvar to empty value, load should fail
*/
err = setenv(TOKEN_ENVVAR, "", 1 /*overwrite*/);
if (!ASSERT_OK(err, "setenv_token_path"))
return -EINVAL;
skel = dummy_st_ops_success__open_and_load();
if (!ASSERT_ERR_PTR(skel, "obj_token_envvar_disabled_load")) {
unsetenv(TOKEN_ENVVAR);
dummy_st_ops_success__destroy(skel);
return -EINVAL;
}
unsetenv(TOKEN_ENVVAR);
/* now the same struct_ops skeleton should succeed thanks to libppf
* creating BPF token from /sys/fs/bpf mount point
*/
skel = dummy_st_ops_success__open_and_load();
if (!ASSERT_OK_PTR(skel, "obj_implicit_token_load"))
return -EINVAL;
dummy_st_ops_success__destroy(skel);
/* now disable implicit token through empty bpf_token_path, should fail */
opts.bpf_token_path = "";
skel = dummy_st_ops_success__open_opts(&opts);
if (!ASSERT_OK_PTR(skel, "obj_empty_token_path_open"))
return -EINVAL;
err = dummy_st_ops_success__load(skel);
dummy_st_ops_success__destroy(skel);
if (!ASSERT_ERR(err, "obj_empty_token_path_load"))
return -EINVAL;
return 0;
}
static int userns_obj_priv_implicit_token_envvar(int mnt_fd, struct token_lsm *lsm_skel)
{
LIBBPF_OPTS(bpf_object_open_opts, opts);
struct dummy_st_ops_success *skel;
int err;
/* before we mount BPF FS with token delegation, struct_ops skeleton
* should fail to load
*/
skel = dummy_st_ops_success__open_and_load();
if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load")) {
dummy_st_ops_success__destroy(skel);
return -EINVAL;
}
/* mount custom BPF FS over custom location, so libbpf can't create
* BPF token implicitly, unless pointed to it through
* LIBBPF_BPF_TOKEN_PATH envvar
*/
rmdir(TOKEN_BPFFS_CUSTOM);
if (!ASSERT_OK(mkdir(TOKEN_BPFFS_CUSTOM, 0777), "mkdir_bpffs_custom"))
goto err_out;
err = sys_move_mount(mnt_fd, "", AT_FDCWD, TOKEN_BPFFS_CUSTOM, MOVE_MOUNT_F_EMPTY_PATH);
if (!ASSERT_OK(err, "move_mount_bpffs"))
goto err_out;
/* even though we have BPF FS with delegation, it's not at default
* /sys/fs/bpf location, so we still fail to load until envvar is set up
*/
skel = dummy_st_ops_success__open_and_load();
if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load2")) {
dummy_st_ops_success__destroy(skel);
goto err_out;
}
err = setenv(TOKEN_ENVVAR, TOKEN_BPFFS_CUSTOM, 1 /*overwrite*/);
if (!ASSERT_OK(err, "setenv_token_path"))
goto err_out;
/* now the same struct_ops skeleton should succeed thanks to libppf
* creating BPF token from custom mount point
*/
skel = dummy_st_ops_success__open_and_load();
if (!ASSERT_OK_PTR(skel, "obj_implicit_token_load"))
goto err_out;
dummy_st_ops_success__destroy(skel);
/* now disable implicit token through empty bpf_token_path, envvar
* will be ignored, should fail
*/
opts.bpf_token_path = "";
skel = dummy_st_ops_success__open_opts(&opts);
if (!ASSERT_OK_PTR(skel, "obj_empty_token_path_open"))
goto err_out;
err = dummy_st_ops_success__load(skel);
dummy_st_ops_success__destroy(skel);
if (!ASSERT_ERR(err, "obj_empty_token_path_load"))
goto err_out;
rmdir(TOKEN_BPFFS_CUSTOM);
unsetenv(TOKEN_ENVVAR);
return 0;
err_out:
rmdir(TOKEN_BPFFS_CUSTOM);
unsetenv(TOKEN_ENVVAR);
return -EINVAL;
}
#define bit(n) (1ULL << (n))
void test_token(void)
{
if (test__start_subtest("map_token")) {
struct bpffs_opts opts = {
.cmds_str = "map_create",
.maps_str = "stack",
};
subtest_userns(&opts, userns_map_create);
}
if (test__start_subtest("btf_token")) {
struct bpffs_opts opts = {
.cmds = 1ULL << BPF_BTF_LOAD,
};
subtest_userns(&opts, userns_btf_load);
}
if (test__start_subtest("prog_token")) {
struct bpffs_opts opts = {
.cmds_str = "PROG_LOAD",
.progs_str = "XDP",
.attachs_str = "xdp",
};
subtest_userns(&opts, userns_prog_load);
}
if (test__start_subtest("obj_priv_map")) {
struct bpffs_opts opts = {
.cmds = bit(BPF_MAP_CREATE),
.maps = bit(BPF_MAP_TYPE_QUEUE),
};
subtest_userns(&opts, userns_obj_priv_map);
}
if (test__start_subtest("obj_priv_prog")) {
struct bpffs_opts opts = {
.cmds = bit(BPF_PROG_LOAD),
.progs = bit(BPF_PROG_TYPE_KPROBE),
.attachs = ~0ULL,
};
subtest_userns(&opts, userns_obj_priv_prog);
}
if (test__start_subtest("obj_priv_btf_fail")) {
struct bpffs_opts opts = {
/* disallow BTF loading */
.cmds = bit(BPF_MAP_CREATE) | bit(BPF_PROG_LOAD),
.maps = bit(BPF_MAP_TYPE_STRUCT_OPS),
.progs = bit(BPF_PROG_TYPE_STRUCT_OPS),
.attachs = ~0ULL,
};
subtest_userns(&opts, userns_obj_priv_btf_fail);
}
if (test__start_subtest("obj_priv_btf_success")) {
struct bpffs_opts opts = {
/* allow BTF loading */
.cmds = bit(BPF_BTF_LOAD) | bit(BPF_MAP_CREATE) | bit(BPF_PROG_LOAD),
.maps = bit(BPF_MAP_TYPE_STRUCT_OPS),
.progs = bit(BPF_PROG_TYPE_STRUCT_OPS),
.attachs = ~0ULL,
};
subtest_userns(&opts, userns_obj_priv_btf_success);
}
if (test__start_subtest("obj_priv_implicit_token")) {
struct bpffs_opts opts = {
/* allow BTF loading */
.cmds = bit(BPF_BTF_LOAD) | bit(BPF_MAP_CREATE) | bit(BPF_PROG_LOAD),
.maps = bit(BPF_MAP_TYPE_STRUCT_OPS),
.progs = bit(BPF_PROG_TYPE_STRUCT_OPS),
.attachs = ~0ULL,
};
subtest_userns(&opts, userns_obj_priv_implicit_token);
}
if (test__start_subtest("obj_priv_implicit_token_envvar")) {
struct bpffs_opts opts = {
/* allow BTF loading */
.cmds = bit(BPF_BTF_LOAD) | bit(BPF_MAP_CREATE) | bit(BPF_PROG_LOAD),
.maps = bit(BPF_MAP_TYPE_STRUCT_OPS),
.progs = bit(BPF_PROG_TYPE_STRUCT_OPS),
.attachs = ~0ULL,
};
subtest_userns(&opts, userns_obj_priv_implicit_token_envvar);
}
}
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