| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Minimal file system backend for holding eBPF maps and programs, |
| * used by bpf(2) object pinning. |
| * |
| * Authors: |
| * |
| * Daniel Borkmann <daniel@iogearbox.net> |
| */ |
| |
| #include <linux/init.h> |
| #include <linux/magic.h> |
| #include <linux/major.h> |
| #include <linux/mount.h> |
| #include <linux/namei.h> |
| #include <linux/fs.h> |
| #include <linux/fs_context.h> |
| #include <linux/fs_parser.h> |
| #include <linux/kdev_t.h> |
| #include <linux/filter.h> |
| #include <linux/bpf.h> |
| #include <linux/bpf_trace.h> |
| |
| enum bpf_type { |
| BPF_TYPE_UNSPEC = 0, |
| BPF_TYPE_PROG, |
| BPF_TYPE_MAP, |
| }; |
| |
| static void *bpf_any_get(void *raw, enum bpf_type type) |
| { |
| switch (type) { |
| case BPF_TYPE_PROG: |
| bpf_prog_inc(raw); |
| break; |
| case BPF_TYPE_MAP: |
| bpf_map_inc_with_uref(raw); |
| break; |
| default: |
| WARN_ON_ONCE(1); |
| break; |
| } |
| |
| return raw; |
| } |
| |
| static void bpf_any_put(void *raw, enum bpf_type type) |
| { |
| switch (type) { |
| case BPF_TYPE_PROG: |
| bpf_prog_put(raw); |
| break; |
| case BPF_TYPE_MAP: |
| bpf_map_put_with_uref(raw); |
| break; |
| default: |
| WARN_ON_ONCE(1); |
| break; |
| } |
| } |
| |
| static void *bpf_fd_probe_obj(u32 ufd, enum bpf_type *type) |
| { |
| void *raw; |
| |
| *type = BPF_TYPE_MAP; |
| raw = bpf_map_get_with_uref(ufd); |
| if (IS_ERR(raw)) { |
| *type = BPF_TYPE_PROG; |
| raw = bpf_prog_get(ufd); |
| } |
| |
| return raw; |
| } |
| |
| static const struct inode_operations bpf_dir_iops; |
| |
| static const struct inode_operations bpf_prog_iops = { }; |
| static const struct inode_operations bpf_map_iops = { }; |
| |
| static struct inode *bpf_get_inode(struct super_block *sb, |
| const struct inode *dir, |
| umode_t mode) |
| { |
| struct inode *inode; |
| |
| switch (mode & S_IFMT) { |
| case S_IFDIR: |
| case S_IFREG: |
| case S_IFLNK: |
| break; |
| default: |
| return ERR_PTR(-EINVAL); |
| } |
| |
| inode = new_inode(sb); |
| if (!inode) |
| return ERR_PTR(-ENOSPC); |
| |
| inode->i_ino = get_next_ino(); |
| inode->i_atime = current_time(inode); |
| inode->i_mtime = inode->i_atime; |
| inode->i_ctime = inode->i_atime; |
| |
| inode_init_owner(inode, dir, mode); |
| |
| return inode; |
| } |
| |
| static int bpf_inode_type(const struct inode *inode, enum bpf_type *type) |
| { |
| *type = BPF_TYPE_UNSPEC; |
| if (inode->i_op == &bpf_prog_iops) |
| *type = BPF_TYPE_PROG; |
| else if (inode->i_op == &bpf_map_iops) |
| *type = BPF_TYPE_MAP; |
| else |
| return -EACCES; |
| |
| return 0; |
| } |
| |
| static void bpf_dentry_finalize(struct dentry *dentry, struct inode *inode, |
| struct inode *dir) |
| { |
| d_instantiate(dentry, inode); |
| dget(dentry); |
| |
| dir->i_mtime = current_time(dir); |
| dir->i_ctime = dir->i_mtime; |
| } |
| |
| static int bpf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
| { |
| struct inode *inode; |
| |
| inode = bpf_get_inode(dir->i_sb, dir, mode | S_IFDIR); |
| if (IS_ERR(inode)) |
| return PTR_ERR(inode); |
| |
| inode->i_op = &bpf_dir_iops; |
| inode->i_fop = &simple_dir_operations; |
| |
| inc_nlink(inode); |
| inc_nlink(dir); |
| |
| bpf_dentry_finalize(dentry, inode, dir); |
| return 0; |
| } |
| |
| struct map_iter { |
| void *key; |
| bool done; |
| }; |
| |
| static struct map_iter *map_iter(struct seq_file *m) |
| { |
| return m->private; |
| } |
| |
| static struct bpf_map *seq_file_to_map(struct seq_file *m) |
| { |
| return file_inode(m->file)->i_private; |
| } |
| |
| static void map_iter_free(struct map_iter *iter) |
| { |
| if (iter) { |
| kfree(iter->key); |
| kfree(iter); |
| } |
| } |
| |
| static struct map_iter *map_iter_alloc(struct bpf_map *map) |
| { |
| struct map_iter *iter; |
| |
| iter = kzalloc(sizeof(*iter), GFP_KERNEL | __GFP_NOWARN); |
| if (!iter) |
| goto error; |
| |
| iter->key = kzalloc(map->key_size, GFP_KERNEL | __GFP_NOWARN); |
| if (!iter->key) |
| goto error; |
| |
| return iter; |
| |
| error: |
| map_iter_free(iter); |
| return NULL; |
| } |
| |
| static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos) |
| { |
| struct bpf_map *map = seq_file_to_map(m); |
| void *key = map_iter(m)->key; |
| void *prev_key; |
| |
| (*pos)++; |
| if (map_iter(m)->done) |
| return NULL; |
| |
| if (unlikely(v == SEQ_START_TOKEN)) |
| prev_key = NULL; |
| else |
| prev_key = key; |
| |
| if (map->ops->map_get_next_key(map, prev_key, key)) { |
| map_iter(m)->done = true; |
| return NULL; |
| } |
| return key; |
| } |
| |
| static void *map_seq_start(struct seq_file *m, loff_t *pos) |
| { |
| if (map_iter(m)->done) |
| return NULL; |
| |
| return *pos ? map_iter(m)->key : SEQ_START_TOKEN; |
| } |
| |
| static void map_seq_stop(struct seq_file *m, void *v) |
| { |
| } |
| |
| static int map_seq_show(struct seq_file *m, void *v) |
| { |
| struct bpf_map *map = seq_file_to_map(m); |
| void *key = map_iter(m)->key; |
| |
| if (unlikely(v == SEQ_START_TOKEN)) { |
| seq_puts(m, "# WARNING!! The output is for debug purpose only\n"); |
| seq_puts(m, "# WARNING!! The output format will change\n"); |
| } else { |
| map->ops->map_seq_show_elem(map, key, m); |
| } |
| |
| return 0; |
| } |
| |
| static const struct seq_operations bpffs_map_seq_ops = { |
| .start = map_seq_start, |
| .next = map_seq_next, |
| .show = map_seq_show, |
| .stop = map_seq_stop, |
| }; |
| |
| static int bpffs_map_open(struct inode *inode, struct file *file) |
| { |
| struct bpf_map *map = inode->i_private; |
| struct map_iter *iter; |
| struct seq_file *m; |
| int err; |
| |
| iter = map_iter_alloc(map); |
| if (!iter) |
| return -ENOMEM; |
| |
| err = seq_open(file, &bpffs_map_seq_ops); |
| if (err) { |
| map_iter_free(iter); |
| return err; |
| } |
| |
| m = file->private_data; |
| m->private = iter; |
| |
| return 0; |
| } |
| |
| static int bpffs_map_release(struct inode *inode, struct file *file) |
| { |
| struct seq_file *m = file->private_data; |
| |
| map_iter_free(map_iter(m)); |
| |
| return seq_release(inode, file); |
| } |
| |
| /* bpffs_map_fops should only implement the basic |
| * read operation for a BPF map. The purpose is to |
| * provide a simple user intuitive way to do |
| * "cat bpffs/pathto/a-pinned-map". |
| * |
| * Other operations (e.g. write, lookup...) should be realized by |
| * the userspace tools (e.g. bpftool) through the |
| * BPF_OBJ_GET_INFO_BY_FD and the map's lookup/update |
| * interface. |
| */ |
| static const struct file_operations bpffs_map_fops = { |
| .open = bpffs_map_open, |
| .read = seq_read, |
| .release = bpffs_map_release, |
| }; |
| |
| static int bpffs_obj_open(struct inode *inode, struct file *file) |
| { |
| return -EIO; |
| } |
| |
| static const struct file_operations bpffs_obj_fops = { |
| .open = bpffs_obj_open, |
| }; |
| |
| static int bpf_mkobj_ops(struct dentry *dentry, umode_t mode, void *raw, |
| const struct inode_operations *iops, |
| const struct file_operations *fops) |
| { |
| struct inode *dir = dentry->d_parent->d_inode; |
| struct inode *inode = bpf_get_inode(dir->i_sb, dir, mode); |
| if (IS_ERR(inode)) |
| return PTR_ERR(inode); |
| |
| inode->i_op = iops; |
| inode->i_fop = fops; |
| inode->i_private = raw; |
| |
| bpf_dentry_finalize(dentry, inode, dir); |
| return 0; |
| } |
| |
| static int bpf_mkprog(struct dentry *dentry, umode_t mode, void *arg) |
| { |
| return bpf_mkobj_ops(dentry, mode, arg, &bpf_prog_iops, |
| &bpffs_obj_fops); |
| } |
| |
| static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg) |
| { |
| struct bpf_map *map = arg; |
| |
| return bpf_mkobj_ops(dentry, mode, arg, &bpf_map_iops, |
| bpf_map_support_seq_show(map) ? |
| &bpffs_map_fops : &bpffs_obj_fops); |
| } |
| |
| static struct dentry * |
| bpf_lookup(struct inode *dir, struct dentry *dentry, unsigned flags) |
| { |
| /* Dots in names (e.g. "/sys/fs/bpf/foo.bar") are reserved for future |
| * extensions. |
| */ |
| if (strchr(dentry->d_name.name, '.')) |
| return ERR_PTR(-EPERM); |
| |
| return simple_lookup(dir, dentry, flags); |
| } |
| |
| static int bpf_symlink(struct inode *dir, struct dentry *dentry, |
| const char *target) |
| { |
| char *link = kstrdup(target, GFP_USER | __GFP_NOWARN); |
| struct inode *inode; |
| |
| if (!link) |
| return -ENOMEM; |
| |
| inode = bpf_get_inode(dir->i_sb, dir, S_IRWXUGO | S_IFLNK); |
| if (IS_ERR(inode)) { |
| kfree(link); |
| return PTR_ERR(inode); |
| } |
| |
| inode->i_op = &simple_symlink_inode_operations; |
| inode->i_link = link; |
| |
| bpf_dentry_finalize(dentry, inode, dir); |
| return 0; |
| } |
| |
| static const struct inode_operations bpf_dir_iops = { |
| .lookup = bpf_lookup, |
| .mkdir = bpf_mkdir, |
| .symlink = bpf_symlink, |
| .rmdir = simple_rmdir, |
| .rename = simple_rename, |
| .link = simple_link, |
| .unlink = simple_unlink, |
| }; |
| |
| static int bpf_obj_do_pin(const char __user *pathname, void *raw, |
| enum bpf_type type) |
| { |
| struct dentry *dentry; |
| struct inode *dir; |
| struct path path; |
| umode_t mode; |
| int ret; |
| |
| dentry = user_path_create(AT_FDCWD, pathname, &path, 0); |
| if (IS_ERR(dentry)) |
| return PTR_ERR(dentry); |
| |
| mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask()); |
| |
| ret = security_path_mknod(&path, dentry, mode, 0); |
| if (ret) |
| goto out; |
| |
| dir = d_inode(path.dentry); |
| if (dir->i_op != &bpf_dir_iops) { |
| ret = -EPERM; |
| goto out; |
| } |
| |
| switch (type) { |
| case BPF_TYPE_PROG: |
| ret = vfs_mkobj(dentry, mode, bpf_mkprog, raw); |
| break; |
| case BPF_TYPE_MAP: |
| ret = vfs_mkobj(dentry, mode, bpf_mkmap, raw); |
| break; |
| default: |
| ret = -EPERM; |
| } |
| out: |
| done_path_create(&path, dentry); |
| return ret; |
| } |
| |
| int bpf_obj_pin_user(u32 ufd, const char __user *pathname) |
| { |
| enum bpf_type type; |
| void *raw; |
| int ret; |
| |
| raw = bpf_fd_probe_obj(ufd, &type); |
| if (IS_ERR(raw)) |
| return PTR_ERR(raw); |
| |
| ret = bpf_obj_do_pin(pathname, raw, type); |
| if (ret != 0) |
| bpf_any_put(raw, type); |
| |
| return ret; |
| } |
| |
| static void *bpf_obj_do_get(const char __user *pathname, |
| enum bpf_type *type, int flags) |
| { |
| struct inode *inode; |
| struct path path; |
| void *raw; |
| int ret; |
| |
| ret = user_path_at(AT_FDCWD, pathname, LOOKUP_FOLLOW, &path); |
| if (ret) |
| return ERR_PTR(ret); |
| |
| inode = d_backing_inode(path.dentry); |
| ret = inode_permission(inode, ACC_MODE(flags)); |
| if (ret) |
| goto out; |
| |
| ret = bpf_inode_type(inode, type); |
| if (ret) |
| goto out; |
| |
| raw = bpf_any_get(inode->i_private, *type); |
| if (!IS_ERR(raw)) |
| touch_atime(&path); |
| |
| path_put(&path); |
| return raw; |
| out: |
| path_put(&path); |
| return ERR_PTR(ret); |
| } |
| |
| int bpf_obj_get_user(const char __user *pathname, int flags) |
| { |
| enum bpf_type type = BPF_TYPE_UNSPEC; |
| int f_flags; |
| void *raw; |
| int ret; |
| |
| f_flags = bpf_get_file_flag(flags); |
| if (f_flags < 0) |
| return f_flags; |
| |
| raw = bpf_obj_do_get(pathname, &type, f_flags); |
| if (IS_ERR(raw)) |
| return PTR_ERR(raw); |
| |
| if (type == BPF_TYPE_PROG) |
| ret = bpf_prog_new_fd(raw); |
| else if (type == BPF_TYPE_MAP) |
| ret = bpf_map_new_fd(raw, f_flags); |
| else |
| return -ENOENT; |
| |
| if (ret < 0) |
| bpf_any_put(raw, type); |
| return ret; |
| } |
| |
| static struct bpf_prog *__get_prog_inode(struct inode *inode, enum bpf_prog_type type) |
| { |
| struct bpf_prog *prog; |
| int ret = inode_permission(inode, MAY_READ); |
| if (ret) |
| return ERR_PTR(ret); |
| |
| if (inode->i_op == &bpf_map_iops) |
| return ERR_PTR(-EINVAL); |
| if (inode->i_op != &bpf_prog_iops) |
| return ERR_PTR(-EACCES); |
| |
| prog = inode->i_private; |
| |
| ret = security_bpf_prog(prog); |
| if (ret < 0) |
| return ERR_PTR(ret); |
| |
| if (!bpf_prog_get_ok(prog, &type, false)) |
| return ERR_PTR(-EINVAL); |
| |
| bpf_prog_inc(prog); |
| return prog; |
| } |
| |
| struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type) |
| { |
| struct bpf_prog *prog; |
| struct path path; |
| int ret = kern_path(name, LOOKUP_FOLLOW, &path); |
| if (ret) |
| return ERR_PTR(ret); |
| prog = __get_prog_inode(d_backing_inode(path.dentry), type); |
| if (!IS_ERR(prog)) |
| touch_atime(&path); |
| path_put(&path); |
| return prog; |
| } |
| EXPORT_SYMBOL(bpf_prog_get_type_path); |
| |
| /* |
| * Display the mount options in /proc/mounts. |
| */ |
| static int bpf_show_options(struct seq_file *m, struct dentry *root) |
| { |
| umode_t mode = d_inode(root)->i_mode & S_IALLUGO & ~S_ISVTX; |
| |
| if (mode != S_IRWXUGO) |
| seq_printf(m, ",mode=%o", mode); |
| return 0; |
| } |
| |
| static void bpf_free_inode(struct inode *inode) |
| { |
| enum bpf_type type; |
| |
| if (S_ISLNK(inode->i_mode)) |
| kfree(inode->i_link); |
| if (!bpf_inode_type(inode, &type)) |
| bpf_any_put(inode->i_private, type); |
| free_inode_nonrcu(inode); |
| } |
| |
| static const struct super_operations bpf_super_ops = { |
| .statfs = simple_statfs, |
| .drop_inode = generic_delete_inode, |
| .show_options = bpf_show_options, |
| .free_inode = bpf_free_inode, |
| }; |
| |
| enum { |
| OPT_MODE, |
| }; |
| |
| static const struct fs_parameter_spec bpf_param_specs[] = { |
| fsparam_u32oct ("mode", OPT_MODE), |
| {} |
| }; |
| |
| static const struct fs_parameter_description bpf_fs_parameters = { |
| .name = "bpf", |
| .specs = bpf_param_specs, |
| }; |
| |
| struct bpf_mount_opts { |
| umode_t mode; |
| }; |
| |
| static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) |
| { |
| struct bpf_mount_opts *opts = fc->fs_private; |
| struct fs_parse_result result; |
| int opt; |
| |
| opt = fs_parse(fc, &bpf_fs_parameters, param, &result); |
| if (opt < 0) |
| /* We might like to report bad mount options here, but |
| * traditionally we've ignored all mount options, so we'd |
| * better continue to ignore non-existing options for bpf. |
| */ |
| return opt == -ENOPARAM ? 0 : opt; |
| |
| switch (opt) { |
| case OPT_MODE: |
| opts->mode = result.uint_32 & S_IALLUGO; |
| break; |
| } |
| |
| return 0; |
| } |
| |
| static int bpf_fill_super(struct super_block *sb, struct fs_context *fc) |
| { |
| static const struct tree_descr bpf_rfiles[] = { { "" } }; |
| struct bpf_mount_opts *opts = fc->fs_private; |
| struct inode *inode; |
| int ret; |
| |
| ret = simple_fill_super(sb, BPF_FS_MAGIC, bpf_rfiles); |
| if (ret) |
| return ret; |
| |
| sb->s_op = &bpf_super_ops; |
| |
| inode = sb->s_root->d_inode; |
| inode->i_op = &bpf_dir_iops; |
| inode->i_mode &= ~S_IALLUGO; |
| inode->i_mode |= S_ISVTX | opts->mode; |
| |
| return 0; |
| } |
| |
| static int bpf_get_tree(struct fs_context *fc) |
| { |
| return get_tree_nodev(fc, bpf_fill_super); |
| } |
| |
| static void bpf_free_fc(struct fs_context *fc) |
| { |
| kfree(fc->fs_private); |
| } |
| |
| static const struct fs_context_operations bpf_context_ops = { |
| .free = bpf_free_fc, |
| .parse_param = bpf_parse_param, |
| .get_tree = bpf_get_tree, |
| }; |
| |
| /* |
| * Set up the filesystem mount context. |
| */ |
| static int bpf_init_fs_context(struct fs_context *fc) |
| { |
| struct bpf_mount_opts *opts; |
| |
| opts = kzalloc(sizeof(struct bpf_mount_opts), GFP_KERNEL); |
| if (!opts) |
| return -ENOMEM; |
| |
| opts->mode = S_IRWXUGO; |
| |
| fc->fs_private = opts; |
| fc->ops = &bpf_context_ops; |
| return 0; |
| } |
| |
| static struct file_system_type bpf_fs_type = { |
| .owner = THIS_MODULE, |
| .name = "bpf", |
| .init_fs_context = bpf_init_fs_context, |
| .parameters = &bpf_fs_parameters, |
| .kill_sb = kill_litter_super, |
| }; |
| |
| static int __init bpf_init(void) |
| { |
| int ret; |
| |
| ret = sysfs_create_mount_point(fs_kobj, "bpf"); |
| if (ret) |
| return ret; |
| |
| ret = register_filesystem(&bpf_fs_type); |
| if (ret) |
| sysfs_remove_mount_point(fs_kobj, "bpf"); |
| |
| return ret; |
| } |
| fs_initcall(bpf_init); |