mirror of https://gitee.com/openkylin/linux.git
470 lines
9.1 KiB
C
470 lines
9.1 KiB
C
/*
|
|
* Minimal file system backend for holding eBPF maps and programs,
|
|
* used by bpf(2) object pinning.
|
|
*
|
|
* 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>
|
|
#include <linux/magic.h>
|
|
#include <linux/major.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/namei.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/kdev_t.h>
|
|
#include <linux/parser.h>
|
|
#include <linux/filter.h>
|
|
#include <linux/bpf.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:
|
|
raw = bpf_prog_inc(raw);
|
|
break;
|
|
case BPF_TYPE_MAP:
|
|
raw = bpf_map_inc(raw, true);
|
|
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;
|
|
}
|
|
|
|
static int bpf_mkobj_ops(struct inode *dir, struct dentry *dentry,
|
|
umode_t mode, const struct inode_operations *iops)
|
|
{
|
|
struct inode *inode;
|
|
|
|
inode = bpf_get_inode(dir->i_sb, dir, mode | S_IFREG);
|
|
if (IS_ERR(inode))
|
|
return PTR_ERR(inode);
|
|
|
|
inode->i_op = iops;
|
|
inode->i_private = dentry->d_fsdata;
|
|
|
|
bpf_dentry_finalize(dentry, inode, dir);
|
|
return 0;
|
|
}
|
|
|
|
static int bpf_mkobj(struct inode *dir, struct dentry *dentry, umode_t mode,
|
|
dev_t devt)
|
|
{
|
|
enum bpf_type type = MINOR(devt);
|
|
|
|
if (MAJOR(devt) != UNNAMED_MAJOR || !S_ISREG(mode) ||
|
|
dentry->d_fsdata == NULL)
|
|
return -EPERM;
|
|
|
|
switch (type) {
|
|
case BPF_TYPE_PROG:
|
|
return bpf_mkobj_ops(dir, dentry, mode, &bpf_prog_iops);
|
|
case BPF_TYPE_MAP:
|
|
return bpf_mkobj_ops(dir, dentry, mode, &bpf_map_iops);
|
|
default:
|
|
return -EPERM;
|
|
}
|
|
}
|
|
|
|
static struct dentry *
|
|
bpf_lookup(struct inode *dir, struct dentry *dentry, unsigned flags)
|
|
{
|
|
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,
|
|
.mknod = bpf_mkobj,
|
|
.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 struct filename *pathname, void *raw,
|
|
enum bpf_type type)
|
|
{
|
|
struct dentry *dentry;
|
|
struct inode *dir;
|
|
struct path path;
|
|
umode_t mode;
|
|
dev_t devt;
|
|
int ret;
|
|
|
|
dentry = kern_path_create(AT_FDCWD, pathname->name, &path, 0);
|
|
if (IS_ERR(dentry))
|
|
return PTR_ERR(dentry);
|
|
|
|
mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask());
|
|
devt = MKDEV(UNNAMED_MAJOR, type);
|
|
|
|
ret = security_path_mknod(&path, dentry, mode, devt);
|
|
if (ret)
|
|
goto out;
|
|
|
|
dir = d_inode(path.dentry);
|
|
if (dir->i_op != &bpf_dir_iops) {
|
|
ret = -EPERM;
|
|
goto out;
|
|
}
|
|
|
|
dentry->d_fsdata = raw;
|
|
ret = vfs_mknod(dir, dentry, mode, devt);
|
|
dentry->d_fsdata = NULL;
|
|
out:
|
|
done_path_create(&path, dentry);
|
|
return ret;
|
|
}
|
|
|
|
int bpf_obj_pin_user(u32 ufd, 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;
|
|
}
|
|
|
|
ret = bpf_obj_do_pin(pname, 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,
|
|
enum bpf_type *type)
|
|
{
|
|
struct inode *inode;
|
|
struct path path;
|
|
void *raw;
|
|
int ret;
|
|
|
|
ret = kern_path(pathname->name, LOOKUP_FOLLOW, &path);
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
|
|
inode = d_backing_inode(path.dentry);
|
|
ret = inode_permission(inode, MAY_WRITE);
|
|
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)
|
|
{
|
|
enum bpf_type type = BPF_TYPE_UNSPEC;
|
|
struct filename *pname;
|
|
int ret = -ENOENT;
|
|
void *raw;
|
|
|
|
pname = getname(pathname);
|
|
if (IS_ERR(pname))
|
|
return PTR_ERR(pname);
|
|
|
|
raw = bpf_obj_do_get(pname, &type);
|
|
if (IS_ERR(raw)) {
|
|
ret = PTR_ERR(raw);
|
|
goto out;
|
|
}
|
|
|
|
if (type == BPF_TYPE_PROG)
|
|
ret = bpf_prog_new_fd(raw);
|
|
else if (type == BPF_TYPE_MAP)
|
|
ret = bpf_map_new_fd(raw);
|
|
else
|
|
goto out;
|
|
|
|
if (ret < 0)
|
|
bpf_any_put(raw, type);
|
|
out:
|
|
putname(pname);
|
|
return ret;
|
|
}
|
|
|
|
static void bpf_evict_inode(struct inode *inode)
|
|
{
|
|
enum bpf_type type;
|
|
|
|
truncate_inode_pages_final(&inode->i_data);
|
|
clear_inode(inode);
|
|
|
|
if (S_ISLNK(inode->i_mode))
|
|
kfree(inode->i_link);
|
|
if (!bpf_inode_type(inode, &type))
|
|
bpf_any_put(inode->i_private, type);
|
|
}
|
|
|
|
static const struct super_operations bpf_super_ops = {
|
|
.statfs = simple_statfs,
|
|
.drop_inode = generic_delete_inode,
|
|
.show_options = generic_show_options,
|
|
.evict_inode = bpf_evict_inode,
|
|
};
|
|
|
|
enum {
|
|
OPT_MODE,
|
|
OPT_ERR,
|
|
};
|
|
|
|
static const match_table_t bpf_mount_tokens = {
|
|
{ OPT_MODE, "mode=%o" },
|
|
{ OPT_ERR, NULL },
|
|
};
|
|
|
|
struct bpf_mount_opts {
|
|
umode_t mode;
|
|
};
|
|
|
|
static int bpf_parse_options(char *data, struct bpf_mount_opts *opts)
|
|
{
|
|
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;
|
|
/* 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 0;
|
|
}
|
|
|
|
static int bpf_fill_super(struct super_block *sb, void *data, int silent)
|
|
{
|
|
static struct tree_descr bpf_rfiles[] = { { "" } };
|
|
struct bpf_mount_opts opts;
|
|
struct inode *inode;
|
|
int ret;
|
|
|
|
save_mount_options(sb, data);
|
|
|
|
ret = bpf_parse_options(data, &opts);
|
|
if (ret)
|
|
return 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 struct dentry *bpf_mount(struct file_system_type *type, int flags,
|
|
const char *dev_name, void *data)
|
|
{
|
|
return mount_nodev(type, flags, data, bpf_fill_super);
|
|
}
|
|
|
|
static struct file_system_type bpf_fs_type = {
|
|
.owner = THIS_MODULE,
|
|
.name = "bpf",
|
|
.mount = bpf_mount,
|
|
.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);
|