1 files changed, 545 insertions, 124 deletions

diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 2ada5e21dfa6..9f866a010dad 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Minimal file system backend for holding eBPF maps and programs,
  * used by bpf(2) object pinning.
@@ -5,10 +6,6 @@
  * Authors:
  *
  *	Daniel Borkmann <daniel@iogearbox.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * version 2 as published by the Free Software Foundation.
  */
 
 #include <linux/init.h>
@@ -17,26 +14,33 @@
 #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/parser.h>
 #include <linux/filter.h>
 #include <linux/bpf.h>
 #include <linux/bpf_trace.h>
+#include <linux/kstrtox.h>
+#include "preload/bpf_preload.h"
 
 enum bpf_type {
 	BPF_TYPE_UNSPEC	= 0,
 	BPF_TYPE_PROG,
 	BPF_TYPE_MAP,
+	BPF_TYPE_LINK,
 };
 
 static void *bpf_any_get(void *raw, enum bpf_type type)
 {
 	switch (type) {
 	case BPF_TYPE_PROG:
-		raw = bpf_prog_inc(raw);
+		bpf_prog_inc(raw);
 		break;
 	case BPF_TYPE_MAP:
-		raw = bpf_map_inc(raw, true);
+		bpf_map_inc_with_uref(raw);
+		break;
+	case BPF_TYPE_LINK:
+		bpf_link_inc(raw);
 		break;
 	default:
 		WARN_ON_ONCE(1);
@@ -55,6 +59,9 @@ static void bpf_any_put(void *raw, enum bpf_type type)
 	case BPF_TYPE_MAP:
 		bpf_map_put_with_uref(raw);
 		break;
+	case BPF_TYPE_LINK:
+		bpf_link_put(raw);
+		break;
 	default:
 		WARN_ON_ONCE(1);
 		break;
@@ -65,24 +72,36 @@ 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)) {
+	if (!IS_ERR(raw)) {
+		*type = BPF_TYPE_MAP;
+		return raw;
+	}
+
+	raw = bpf_prog_get(ufd);
+	if (!IS_ERR(raw)) {
 		*type = BPF_TYPE_PROG;
-		raw = bpf_prog_get(ufd);
+		return raw;
 	}
 
-	return raw;
+	raw = bpf_link_get_from_fd(ufd);
+	if (!IS_ERR(raw)) {
+		*type = BPF_TYPE_LINK;
+		return raw;
+	}
+
+	return ERR_PTR(-EINVAL);
 }
 
 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 const struct inode_operations bpf_link_iops  = { };
 
-static struct inode *bpf_get_inode(struct super_block *sb,
-				   const struct inode *dir,
-				   umode_t mode)
+struct inode *bpf_get_inode(struct super_block *sb,
+			    const struct inode *dir,
+			    umode_t mode)
 {
 	struct inode *inode;
 
@@ -100,11 +119,9 @@ static struct inode *bpf_get_inode(struct super_block *sb,
 		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;
+	simple_inode_init_ts(inode);
 
-	inode_init_owner(inode, dir, mode);
+	inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
 
 	return inode;
 }
@@ -116,6 +133,8 @@ static int bpf_inode_type(const struct inode *inode, enum bpf_type *type)
 		*type = BPF_TYPE_PROG;
 	else if (inode->i_op == &bpf_map_iops)
 		*type = BPF_TYPE_MAP;
+	else if (inode->i_op == &bpf_link_iops)
+		*type = BPF_TYPE_LINK;
 	else
 		return -EACCES;
 
@@ -125,20 +144,19 @@ static int bpf_inode_type(const struct inode *inode, enum bpf_type *type)
 static void bpf_dentry_finalize(struct dentry *dentry, struct inode *inode,
 				struct inode *dir)
 {
-	d_instantiate(dentry, inode);
-	dget(dentry);
+	d_make_persistent(dentry, inode);
 
-	dir->i_mtime = current_time(dir);
-	dir->i_ctime = dir->i_mtime;
+	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
 }
 
-static int bpf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+static struct dentry *bpf_mkdir(struct mnt_idmap *idmap, 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);
+		return ERR_CAST(inode);
 
 	inode->i_op = &bpf_dir_iops;
 	inode->i_fop = &simple_dir_operations;
@@ -147,7 +165,7 @@ static int bpf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 	inc_nlink(dir);
 
 	bpf_dentry_finalize(dentry, inode, dir);
-	return 0;
+	return NULL;
 }
 
 struct map_iter {
@@ -198,6 +216,7 @@ static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
 	void *key = map_iter(m)->key;
 	void *prev_key;
 
+	(*pos)++;
 	if (map_iter(m)->done)
 		return NULL;
 
@@ -206,12 +225,12 @@ static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
 	else
 		prev_key = key;
 
+	rcu_read_lock();
 	if (map->ops->map_get_next_key(map, prev_key, key)) {
 		map_iter(m)->done = true;
-		return NULL;
+		key = NULL;
 	}
-
-	++(*pos);
+	rcu_read_unlock();
 	return key;
 }
 
@@ -338,20 +357,30 @@ static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg)
 			     &bpffs_map_fops : &bpffs_obj_fops);
 }
 
+static int bpf_mklink(struct dentry *dentry, umode_t mode, void *arg)
+{
+	struct bpf_link *link = arg;
+
+	return bpf_mkobj_ops(dentry, mode, arg, &bpf_link_iops,
+			     bpf_link_is_iter(link) ?
+			     &bpf_iter_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.
+	 * extensions. That allows popoulate_bpffs() create special files.
 	 */
-	if (strchr(dentry->d_name.name, '.'))
+	if ((dir->i_mode & S_IALLUGO) &&
+	    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)
+static int bpf_symlink(struct mnt_idmap *idmap, struct inode *dir,
+		       struct dentry *dentry, const char *target)
 {
 	char *link = kstrdup(target, GFP_USER | __GFP_NOWARN);
 	struct inode *inode;
@@ -382,7 +411,24 @@ static const struct inode_operations bpf_dir_iops = {
 	.unlink		= simple_unlink,
 };
 
-static int bpf_obj_do_pin(const struct filename *pathname, void *raw,
+/* pin iterator link into bpffs */
+static int bpf_iter_link_pin_kernel(struct dentry *parent,
+				    const char *name, struct bpf_link *link)
+{
+	umode_t mode = S_IFREG | S_IRUSR;
+	struct dentry *dentry;
+	int ret;
+
+	dentry = simple_start_creating(parent, name);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+	ret = bpf_mkobj_ops(dentry, mode, link, &bpf_link_iops,
+			    &bpf_iter_fops);
+	simple_done_creating(dentry);
+	return ret;
+}
+
+static int bpf_obj_do_pin(int path_fd, const char __user *pathname, void *raw,
 			  enum bpf_type type)
 {
 	struct dentry *dentry;
@@ -391,22 +437,21 @@ static int bpf_obj_do_pin(const struct filename *pathname, void *raw,
 	umode_t mode;
 	int ret;
 
-	dentry = kern_path_create(AT_FDCWD, pathname->name, &path, 0);
+	dentry = start_creating_user_path(path_fd, 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;
 	}
 
+	mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask());
+	ret = security_path_mknod(&path, dentry, mode, 0);
+	if (ret)
+		goto out;
+
 	switch (type) {
 	case BPF_TYPE_PROG:
 		ret = vfs_mkobj(dentry, mode, bpf_mkprog, raw);
@@ -414,40 +459,35 @@ static int bpf_obj_do_pin(const struct filename *pathname, void *raw,
 	case BPF_TYPE_MAP:
 		ret = vfs_mkobj(dentry, mode, bpf_mkmap, raw);
 		break;
+	case BPF_TYPE_LINK:
+		ret = vfs_mkobj(dentry, mode, bpf_mklink, raw);
+		break;
 	default:
 		ret = -EPERM;
 	}
 out:
-	done_path_create(&path, dentry);
+	end_creating_path(&path, dentry);
 	return ret;
 }
 
-int bpf_obj_pin_user(u32 ufd, const char __user *pathname)
+int bpf_obj_pin_user(u32 ufd, int path_fd, const char __user *pathname)
 {
-	struct filename *pname;
 	enum bpf_type type;
 	void *raw;
 	int ret;
 
-	pname = getname(pathname);
-	if (IS_ERR(pname))
-		return PTR_ERR(pname);
-
 	raw = bpf_fd_probe_obj(ufd, &type);
-	if (IS_ERR(raw)) {
-		ret = PTR_ERR(raw);
-		goto out;
-	}
+	if (IS_ERR(raw))
+		return PTR_ERR(raw);
 
-	ret = bpf_obj_do_pin(pname, raw, type);
+	ret = bpf_obj_do_pin(path_fd, pathname, raw, type);
 	if (ret != 0)
 		bpf_any_put(raw, type);
-out:
-	putname(pname);
+
 	return ret;
 }
 
-static void *bpf_obj_do_get(const struct filename *pathname,
+static void *bpf_obj_do_get(int path_fd, const char __user *pathname,
 			    enum bpf_type *type, int flags)
 {
 	struct inode *inode;
@@ -455,12 +495,12 @@ static void *bpf_obj_do_get(const struct filename *pathname,
 	void *raw;
 	int ret;
 
-	ret = kern_path(pathname->name, LOOKUP_FOLLOW, &path);
+	ret = user_path_at(path_fd, pathname, LOOKUP_FOLLOW, &path);
 	if (ret)
 		return ERR_PTR(ret);
 
 	inode = d_backing_inode(path.dentry);
-	ret = inode_permission(inode, ACC_MODE(flags));
+	ret = path_permission(&path, ACC_MODE(flags));
 	if (ret)
 		goto out;
 
@@ -479,51 +519,46 @@ out:
 	return ERR_PTR(ret);
 }
 
-int bpf_obj_get_user(const char __user *pathname, int flags)
+int bpf_obj_get_user(int path_fd, const char __user *pathname, int flags)
 {
 	enum bpf_type type = BPF_TYPE_UNSPEC;
-	struct filename *pname;
-	int ret = -ENOENT;
 	int f_flags;
 	void *raw;
+	int ret;
 
 	f_flags = bpf_get_file_flag(flags);
 	if (f_flags < 0)
 		return f_flags;
 
-	pname = getname(pathname);
-	if (IS_ERR(pname))
-		return PTR_ERR(pname);
-
-	raw = bpf_obj_do_get(pname, &type, f_flags);
-	if (IS_ERR(raw)) {
-		ret = PTR_ERR(raw);
-		goto out;
-	}
+	raw = bpf_obj_do_get(path_fd, 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 if (type == BPF_TYPE_LINK)
+		ret = (f_flags != O_RDWR) ? -EINVAL : bpf_link_new_fd(raw);
 	else
-		goto out;
+		return -ENOENT;
 
 	if (ret < 0)
 		bpf_any_put(raw, type);
-out:
-	putname(pname);
 	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 | MAY_WRITE);
+	int ret = inode_permission(&nop_mnt_idmap, 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_link_iops)
+		return ERR_PTR(-EINVAL);
 	if (inode->i_op != &bpf_prog_iops)
 		return ERR_PTR(-EACCES);
 
@@ -536,7 +571,8 @@ static struct bpf_prog *__get_prog_inode(struct inode *inode, enum bpf_prog_type
 	if (!bpf_prog_get_ok(prog, &type, false))
 		return ERR_PTR(-EINVAL);
 
-	return bpf_prog_inc(prog);
+	bpf_prog_inc(prog);
+	return prog;
 }
 
 struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type)
@@ -554,17 +590,134 @@ struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type typ
 }
 EXPORT_SYMBOL(bpf_prog_get_type_path);
 
-static void bpf_evict_inode(struct inode *inode)
+struct bpffs_btf_enums {
+	const struct btf *btf;
+	const struct btf_type *cmd_t;
+	const struct btf_type *map_t;
+	const struct btf_type *prog_t;
+	const struct btf_type *attach_t;
+};
+
+static int find_bpffs_btf_enums(struct bpffs_btf_enums *info)
 {
-	enum bpf_type type;
+	const struct btf *btf;
+	const struct btf_type *t;
+	const char *name;
+	int i, n;
 
-	truncate_inode_pages_final(&inode->i_data);
-	clear_inode(inode);
+	memset(info, 0, sizeof(*info));
 
-	if (S_ISLNK(inode->i_mode))
-		kfree(inode->i_link);
-	if (!bpf_inode_type(inode, &type))
-		bpf_any_put(inode->i_private, type);
+	btf = bpf_get_btf_vmlinux();
+	if (IS_ERR(btf))
+		return PTR_ERR(btf);
+	if (!btf)
+		return -ENOENT;
+
+	info->btf = btf;
+
+	for (i = 1, n = btf_nr_types(btf); i < n; i++) {
+		t = btf_type_by_id(btf, i);
+		if (!btf_type_is_enum(t))
+			continue;
+
+		name = btf_name_by_offset(btf, t->name_off);
+		if (!name)
+			continue;
+
+		if (strcmp(name, "bpf_cmd") == 0)
+			info->cmd_t = t;
+		else if (strcmp(name, "bpf_map_type") == 0)
+			info->map_t = t;
+		else if (strcmp(name, "bpf_prog_type") == 0)
+			info->prog_t = t;
+		else if (strcmp(name, "bpf_attach_type") == 0)
+			info->attach_t = t;
+		else
+			continue;
+
+		if (info->cmd_t && info->map_t && info->prog_t && info->attach_t)
+			return 0;
+	}
+
+	return -ESRCH;
+}
+
+static bool find_btf_enum_const(const struct btf *btf, const struct btf_type *enum_t,
+				const char *prefix, const char *str, int *value)
+{
+	const struct btf_enum *e;
+	const char *name;
+	int i, n, pfx_len = strlen(prefix);
+
+	*value = 0;
+
+	if (!btf || !enum_t)
+		return false;
+
+	for (i = 0, n = btf_vlen(enum_t); i < n; i++) {
+		e = &btf_enum(enum_t)[i];
+
+		name = btf_name_by_offset(btf, e->name_off);
+		if (!name || strncasecmp(name, prefix, pfx_len) != 0)
+			continue;
+
+		/* match symbolic name case insensitive and ignoring prefix */
+		if (strcasecmp(name + pfx_len, str) == 0) {
+			*value = e->val;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static void seq_print_delegate_opts(struct seq_file *m,
+				    const char *opt_name,
+				    const struct btf *btf,
+				    const struct btf_type *enum_t,
+				    const char *prefix,
+				    u64 delegate_msk, u64 any_msk)
+{
+	const struct btf_enum *e;
+	bool first = true;
+	const char *name;
+	u64 msk;
+	int i, n, pfx_len = strlen(prefix);
+
+	delegate_msk &= any_msk; /* clear unknown bits */
+
+	if (delegate_msk == 0)
+		return;
+
+	seq_printf(m, ",%s", opt_name);
+	if (delegate_msk == any_msk) {
+		seq_printf(m, "=any");
+		return;
+	}
+
+	if (btf && enum_t) {
+		for (i = 0, n = btf_vlen(enum_t); i < n; i++) {
+			e = &btf_enum(enum_t)[i];
+			name = btf_name_by_offset(btf, e->name_off);
+			if (!name || strncasecmp(name, prefix, pfx_len) != 0)
+				continue;
+			msk = 1ULL << e->val;
+			if (delegate_msk & msk) {
+				/* emit lower-case name without prefix */
+				seq_putc(m, first ? '=' : ':');
+				name += pfx_len;
+				while (*name) {
+					seq_putc(m, tolower(*name));
+					name++;
+				}
+
+				delegate_msk &= ~msk;
+				first = false;
+			}
+		}
+	}
+	if (delegate_msk)
+		seq_printf(m, "%c0x%llx", first ? '=' : ':', delegate_msk);
 }
 
 /*
@@ -572,73 +725,293 @@ static void bpf_evict_inode(struct inode *inode)
  */
 static int bpf_show_options(struct seq_file *m, struct dentry *root)
 {
-	umode_t mode = d_inode(root)->i_mode & S_IALLUGO & ~S_ISVTX;
-
+	struct inode *inode = d_inode(root);
+	umode_t mode = inode->i_mode & S_IALLUGO & ~S_ISVTX;
+	struct bpf_mount_opts *opts = root->d_sb->s_fs_info;
+	u64 mask;
+
+	if (!uid_eq(inode->i_uid, GLOBAL_ROOT_UID))
+		seq_printf(m, ",uid=%u",
+			   from_kuid_munged(&init_user_ns, inode->i_uid));
+	if (!gid_eq(inode->i_gid, GLOBAL_ROOT_GID))
+		seq_printf(m, ",gid=%u",
+			   from_kgid_munged(&init_user_ns, inode->i_gid));
 	if (mode != S_IRWXUGO)
 		seq_printf(m, ",mode=%o", mode);
+
+	if (opts->delegate_cmds || opts->delegate_maps ||
+	    opts->delegate_progs || opts->delegate_attachs) {
+		struct bpffs_btf_enums info;
+
+		/* ignore errors, fallback to hex */
+		(void)find_bpffs_btf_enums(&info);
+
+		mask = (1ULL << __MAX_BPF_CMD) - 1;
+		seq_print_delegate_opts(m, "delegate_cmds",
+					info.btf, info.cmd_t, "BPF_",
+					opts->delegate_cmds, mask);
+
+		mask = (1ULL << __MAX_BPF_MAP_TYPE) - 1;
+		seq_print_delegate_opts(m, "delegate_maps",
+					info.btf, info.map_t, "BPF_MAP_TYPE_",
+					opts->delegate_maps, mask);
+
+		mask = (1ULL << __MAX_BPF_PROG_TYPE) - 1;
+		seq_print_delegate_opts(m, "delegate_progs",
+					info.btf, info.prog_t, "BPF_PROG_TYPE_",
+					opts->delegate_progs, mask);
+
+		mask = (1ULL << __MAX_BPF_ATTACH_TYPE) - 1;
+		seq_print_delegate_opts(m, "delegate_attachs",
+					info.btf, info.attach_t, "BPF_",
+					opts->delegate_attachs, mask);
+	}
+
 	return 0;
 }
 
-static const struct super_operations bpf_super_ops = {
+static void bpf_destroy_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);
+}
+
+const struct super_operations bpf_super_ops = {
 	.statfs		= simple_statfs,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.show_options	= bpf_show_options,
-	.evict_inode	= bpf_evict_inode,
+	.destroy_inode	= bpf_destroy_inode,
 };
 
 enum {
+	OPT_UID,
+	OPT_GID,
 	OPT_MODE,
-	OPT_ERR,
+	OPT_DELEGATE_CMDS,
+	OPT_DELEGATE_MAPS,
+	OPT_DELEGATE_PROGS,
+	OPT_DELEGATE_ATTACHS,
 };
 
-static const match_table_t bpf_mount_tokens = {
-	{ OPT_MODE, "mode=%o" },
-	{ OPT_ERR, NULL },
-};
-
-struct bpf_mount_opts {
-	umode_t mode;
+static const struct fs_parameter_spec bpf_fs_parameters[] = {
+	fsparam_u32	("uid",				OPT_UID),
+	fsparam_u32	("gid",				OPT_GID),
+	fsparam_u32oct	("mode",			OPT_MODE),
+	fsparam_string	("delegate_cmds",		OPT_DELEGATE_CMDS),
+	fsparam_string	("delegate_maps",		OPT_DELEGATE_MAPS),
+	fsparam_string	("delegate_progs",		OPT_DELEGATE_PROGS),
+	fsparam_string	("delegate_attachs",		OPT_DELEGATE_ATTACHS),
+	{}
 };
 
-static int bpf_parse_options(char *data, struct bpf_mount_opts *opts)
+static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param)
 {
-	substring_t args[MAX_OPT_ARGS];
-	int option, token;
-	char *ptr;
-
-	opts->mode = S_IRWXUGO;
-
-	while ((ptr = strsep(&data, ",")) != NULL) {
-		if (!*ptr)
-			continue;
-
-		token = match_token(ptr, bpf_mount_tokens, args);
-		switch (token) {
-		case OPT_MODE:
-			if (match_octal(&args[0], &option))
-				return -EINVAL;
-			opts->mode = option & S_IALLUGO;
-			break;
+	struct bpf_mount_opts *opts = fc->s_fs_info;
+	struct fs_parse_result result;
+	kuid_t uid;
+	kgid_t gid;
+	int opt, err;
+
+	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.
 		 */
+		if (opt == -ENOPARAM) {
+			opt = vfs_parse_fs_param_source(fc, param);
+			if (opt != -ENOPARAM)
+				return opt;
+
+			return 0;
 		}
+
+		if (opt < 0)
+			return opt;
+	}
+
+	switch (opt) {
+	case OPT_UID:
+		uid = make_kuid(current_user_ns(), result.uint_32);
+		if (!uid_valid(uid))
+			goto bad_value;
+
+		/*
+		 * The requested uid must be representable in the
+		 * filesystem's idmapping.
+		 */
+		if (!kuid_has_mapping(fc->user_ns, uid))
+			goto bad_value;
+
+		opts->uid = uid;
+		break;
+	case OPT_GID:
+		gid = make_kgid(current_user_ns(), result.uint_32);
+		if (!gid_valid(gid))
+			goto bad_value;
+
+		/*
+		 * The requested gid must be representable in the
+		 * filesystem's idmapping.
+		 */
+		if (!kgid_has_mapping(fc->user_ns, gid))
+			goto bad_value;
+
+		opts->gid = gid;
+		break;
+	case OPT_MODE:
+		opts->mode = result.uint_32 & S_IALLUGO;
+		break;
+	case OPT_DELEGATE_CMDS:
+	case OPT_DELEGATE_MAPS:
+	case OPT_DELEGATE_PROGS:
+	case OPT_DELEGATE_ATTACHS: {
+		struct bpffs_btf_enums info;
+		const struct btf_type *enum_t;
+		const char *enum_pfx;
+		u64 *delegate_msk, msk = 0;
+		char *p, *str;
+		int val;
+
+		/* ignore errors, fallback to hex */
+		(void)find_bpffs_btf_enums(&info);
+
+		switch (opt) {
+		case OPT_DELEGATE_CMDS:
+			delegate_msk = &opts->delegate_cmds;
+			enum_t = info.cmd_t;
+			enum_pfx = "BPF_";
+			break;
+		case OPT_DELEGATE_MAPS:
+			delegate_msk = &opts->delegate_maps;
+			enum_t = info.map_t;
+			enum_pfx = "BPF_MAP_TYPE_";
+			break;
+		case OPT_DELEGATE_PROGS:
+			delegate_msk = &opts->delegate_progs;
+			enum_t = info.prog_t;
+			enum_pfx = "BPF_PROG_TYPE_";
+			break;
+		case OPT_DELEGATE_ATTACHS:
+			delegate_msk = &opts->delegate_attachs;
+			enum_t = info.attach_t;
+			enum_pfx = "BPF_";
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		str = param->string;
+		while ((p = strsep(&str, ":"))) {
+			if (strcmp(p, "any") == 0) {
+				msk |= ~0ULL;
+			} else if (find_btf_enum_const(info.btf, enum_t, enum_pfx, p, &val)) {
+				msk |= 1ULL << val;
+			} else {
+				err = kstrtou64(p, 0, &msk);
+				if (err)
+					return err;
+			}
+		}
+
+		/* Setting delegation mount options requires privileges */
+		if (msk && !capable(CAP_SYS_ADMIN))
+			return -EPERM;
+
+		*delegate_msk |= msk;
+		break;
+	}
+	default:
+		/* ignore unknown mount options */
+		break;
 	}
 
 	return 0;
+bad_value:
+	return invalfc(fc, "Bad value for '%s'", param->key);
+}
+
+struct bpf_preload_ops *bpf_preload_ops;
+EXPORT_SYMBOL_GPL(bpf_preload_ops);
+
+static bool bpf_preload_mod_get(void)
+{
+	/* If bpf_preload.ko wasn't loaded earlier then load it now.
+	 * When bpf_preload is built into vmlinux the module's __init
+	 * function will populate it.
+	 */
+	if (!bpf_preload_ops) {
+		request_module("bpf_preload");
+		if (!bpf_preload_ops)
+			return false;
+	}
+	/* And grab the reference, so the module doesn't disappear while the
+	 * kernel is interacting with the kernel module and its UMD.
+	 */
+	if (!try_module_get(bpf_preload_ops->owner)) {
+		pr_err("bpf_preload module get failed.\n");
+		return false;
+	}
+	return true;
+}
+
+static void bpf_preload_mod_put(void)
+{
+	if (bpf_preload_ops)
+		/* now user can "rmmod bpf_preload" if necessary */
+		module_put(bpf_preload_ops->owner);
 }
 
-static int bpf_fill_super(struct super_block *sb, void *data, int silent)
+static DEFINE_MUTEX(bpf_preload_lock);
+
+static int populate_bpffs(struct dentry *parent)
+{
+	struct bpf_preload_info objs[BPF_PRELOAD_LINKS] = {};
+	int err = 0, i;
+
+	/* grab the mutex to make sure the kernel interactions with bpf_preload
+	 * are serialized
+	 */
+	mutex_lock(&bpf_preload_lock);
+
+	/* if bpf_preload.ko wasn't built into vmlinux then load it */
+	if (!bpf_preload_mod_get())
+		goto out;
+
+	err = bpf_preload_ops->preload(objs);
+	if (err)
+		goto out_put;
+	for (i = 0; i < BPF_PRELOAD_LINKS; i++) {
+		bpf_link_inc(objs[i].link);
+		err = bpf_iter_link_pin_kernel(parent,
+					       objs[i].link_name, objs[i].link);
+		if (err) {
+			bpf_link_put(objs[i].link);
+			goto out_put;
+		}
+	}
+out_put:
+	bpf_preload_mod_put();
+out:
+	mutex_unlock(&bpf_preload_lock);
+	return err;
+}
+
+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;
+	struct bpf_mount_opts *opts = sb->s_fs_info;
 	struct inode *inode;
 	int ret;
 
-	ret = bpf_parse_options(data, &opts);
-	if (ret)
-		return ret;
+	/* Mounting an instance of BPF FS requires privileges */
+	if (fc->user_ns != &init_user_ns && !capable(CAP_SYS_ADMIN))
+		return -EPERM;
 
 	ret = simple_fill_super(sb, BPF_FS_MAGIC, bpf_rfiles);
 	if (ret)
@@ -647,24 +1020,72 @@ static int bpf_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_op = &bpf_super_ops;
 
 	inode = sb->s_root->d_inode;
+	inode->i_uid = opts->uid;
+	inode->i_gid = opts->gid;
 	inode->i_op = &bpf_dir_iops;
 	inode->i_mode &= ~S_IALLUGO;
-	inode->i_mode |= S_ISVTX | opts.mode;
+	populate_bpffs(sb->s_root);
+	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->s_fs_info);
+}
 
+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;
+	opts->uid = current_fsuid();
+	opts->gid = current_fsgid();
+
+	/* start out with no BPF token delegation enabled */
+	opts->delegate_cmds = 0;
+	opts->delegate_maps = 0;
+	opts->delegate_progs = 0;
+	opts->delegate_attachs = 0;
+
+	fc->s_fs_info = opts;
+	fc->ops = &bpf_context_ops;
 	return 0;
 }
 
-static struct dentry *bpf_mount(struct file_system_type *type, int flags,
-				const char *dev_name, void *data)
+static void bpf_kill_super(struct super_block *sb)
 {
-	return mount_nodev(type, flags, data, bpf_fill_super);
+	struct bpf_mount_opts *opts = sb->s_fs_info;
+
+	kill_anon_super(sb);
+	kfree(opts);
 }
 
 static struct file_system_type bpf_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "bpf",
-	.mount		= bpf_mount,
-	.kill_sb	= kill_litter_super,
+	.init_fs_context = bpf_init_fs_context,
+	.parameters	= bpf_fs_parameters,
+	.kill_sb	= bpf_kill_super,
+	.fs_flags	= FS_USERNS_MOUNT,
 };
 
 static int __init bpf_init(void)