mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-16 02:06:49 +07:00
bb35a6ef7d
Add support for renaming and hard links to the fs. Most of this can be implemented by using simple library operations under the same constraints that we don't use a reserved name like elsewhere. Linking can be useful to share/manage things like maps across subsystem users. It works within the file system boundary, but is not allowed for directories. Symbolic links are explicitly not implemented here, as it can be better done already by doing bind mounts inside bpf fs to set up shared directories f.e. useful when using volumes in docker containers that map a private working directory into /sys/fs/bpf/ which contains itself a bind mounted path from the host's /sys/fs/bpf/ mount that is shared among multiple containers. For single maps instead of whole directory, hard links can be easily used to do the same. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
408 lines
7.9 KiB
C
408 lines
7.9 KiB
C
/*
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* Minimal file system backend for holding eBPF maps and programs,
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* used by bpf(2) object pinning.
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*
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* Authors:
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*
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* Daniel Borkmann <daniel@iogearbox.net>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 2 as published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/magic.h>
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#include <linux/major.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/fs.h>
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#include <linux/kdev_t.h>
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#include <linux/filter.h>
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#include <linux/bpf.h>
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enum bpf_type {
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BPF_TYPE_UNSPEC = 0,
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BPF_TYPE_PROG,
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BPF_TYPE_MAP,
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};
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static void *bpf_any_get(void *raw, enum bpf_type type)
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{
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switch (type) {
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case BPF_TYPE_PROG:
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atomic_inc(&((struct bpf_prog *)raw)->aux->refcnt);
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break;
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case BPF_TYPE_MAP:
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bpf_map_inc(raw, true);
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break;
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default:
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WARN_ON_ONCE(1);
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break;
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}
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return raw;
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}
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static void bpf_any_put(void *raw, enum bpf_type type)
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{
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switch (type) {
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case BPF_TYPE_PROG:
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bpf_prog_put(raw);
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break;
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case BPF_TYPE_MAP:
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bpf_map_put_with_uref(raw);
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break;
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default:
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WARN_ON_ONCE(1);
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break;
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}
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}
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static void *bpf_fd_probe_obj(u32 ufd, enum bpf_type *type)
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{
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void *raw;
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*type = BPF_TYPE_MAP;
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raw = bpf_map_get_with_uref(ufd);
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if (IS_ERR(raw)) {
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*type = BPF_TYPE_PROG;
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raw = bpf_prog_get(ufd);
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}
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return raw;
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}
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static const struct inode_operations bpf_dir_iops;
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static const struct inode_operations bpf_prog_iops = { };
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static const struct inode_operations bpf_map_iops = { };
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static struct inode *bpf_get_inode(struct super_block *sb,
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const struct inode *dir,
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umode_t mode)
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{
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struct inode *inode;
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switch (mode & S_IFMT) {
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case S_IFDIR:
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case S_IFREG:
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break;
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default:
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return ERR_PTR(-EINVAL);
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}
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inode = new_inode(sb);
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if (!inode)
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return ERR_PTR(-ENOSPC);
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inode->i_ino = get_next_ino();
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inode->i_atime = CURRENT_TIME;
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inode->i_mtime = inode->i_atime;
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inode->i_ctime = inode->i_atime;
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inode_init_owner(inode, dir, mode);
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return inode;
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}
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static int bpf_inode_type(const struct inode *inode, enum bpf_type *type)
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{
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*type = BPF_TYPE_UNSPEC;
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if (inode->i_op == &bpf_prog_iops)
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*type = BPF_TYPE_PROG;
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else if (inode->i_op == &bpf_map_iops)
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*type = BPF_TYPE_MAP;
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else
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return -EACCES;
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return 0;
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}
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static bool bpf_dname_reserved(const struct dentry *dentry)
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{
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return strchr(dentry->d_name.name, '.');
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}
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static int bpf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
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{
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struct inode *inode;
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if (bpf_dname_reserved(dentry))
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return -EPERM;
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inode = bpf_get_inode(dir->i_sb, dir, mode | S_IFDIR);
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if (IS_ERR(inode))
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return PTR_ERR(inode);
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inode->i_op = &bpf_dir_iops;
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inode->i_fop = &simple_dir_operations;
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inc_nlink(inode);
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inc_nlink(dir);
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d_instantiate(dentry, inode);
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dget(dentry);
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return 0;
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}
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static int bpf_mkobj_ops(struct inode *dir, struct dentry *dentry,
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umode_t mode, const struct inode_operations *iops)
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{
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struct inode *inode;
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if (bpf_dname_reserved(dentry))
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return -EPERM;
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inode = bpf_get_inode(dir->i_sb, dir, mode | S_IFREG);
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if (IS_ERR(inode))
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return PTR_ERR(inode);
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inode->i_op = iops;
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inode->i_private = dentry->d_fsdata;
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d_instantiate(dentry, inode);
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dget(dentry);
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return 0;
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}
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static int bpf_mkobj(struct inode *dir, struct dentry *dentry, umode_t mode,
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dev_t devt)
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{
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enum bpf_type type = MINOR(devt);
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if (MAJOR(devt) != UNNAMED_MAJOR || !S_ISREG(mode) ||
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dentry->d_fsdata == NULL)
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return -EPERM;
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switch (type) {
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case BPF_TYPE_PROG:
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return bpf_mkobj_ops(dir, dentry, mode, &bpf_prog_iops);
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case BPF_TYPE_MAP:
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return bpf_mkobj_ops(dir, dentry, mode, &bpf_map_iops);
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default:
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return -EPERM;
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}
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}
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static int bpf_link(struct dentry *old_dentry, struct inode *dir,
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struct dentry *new_dentry)
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{
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if (bpf_dname_reserved(new_dentry))
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return -EPERM;
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return simple_link(old_dentry, dir, new_dentry);
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}
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static int bpf_rename(struct inode *old_dir, struct dentry *old_dentry,
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struct inode *new_dir, struct dentry *new_dentry)
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{
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if (bpf_dname_reserved(new_dentry))
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return -EPERM;
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return simple_rename(old_dir, old_dentry, new_dir, new_dentry);
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}
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static const struct inode_operations bpf_dir_iops = {
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.lookup = simple_lookup,
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.mknod = bpf_mkobj,
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.mkdir = bpf_mkdir,
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.rmdir = simple_rmdir,
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.rename = bpf_rename,
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.link = bpf_link,
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.unlink = simple_unlink,
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};
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static int bpf_obj_do_pin(const struct filename *pathname, void *raw,
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enum bpf_type type)
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{
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struct dentry *dentry;
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struct inode *dir;
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struct path path;
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umode_t mode;
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dev_t devt;
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int ret;
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dentry = kern_path_create(AT_FDCWD, pathname->name, &path, 0);
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if (IS_ERR(dentry))
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return PTR_ERR(dentry);
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mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask());
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devt = MKDEV(UNNAMED_MAJOR, type);
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ret = security_path_mknod(&path, dentry, mode, devt);
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if (ret)
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goto out;
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dir = d_inode(path.dentry);
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if (dir->i_op != &bpf_dir_iops) {
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ret = -EPERM;
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goto out;
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}
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dentry->d_fsdata = raw;
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ret = vfs_mknod(dir, dentry, mode, devt);
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dentry->d_fsdata = NULL;
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out:
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done_path_create(&path, dentry);
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return ret;
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}
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int bpf_obj_pin_user(u32 ufd, const char __user *pathname)
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{
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struct filename *pname;
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enum bpf_type type;
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void *raw;
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int ret;
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pname = getname(pathname);
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if (IS_ERR(pname))
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return PTR_ERR(pname);
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raw = bpf_fd_probe_obj(ufd, &type);
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if (IS_ERR(raw)) {
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ret = PTR_ERR(raw);
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goto out;
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}
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ret = bpf_obj_do_pin(pname, raw, type);
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if (ret != 0)
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bpf_any_put(raw, type);
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out:
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putname(pname);
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return ret;
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}
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static void *bpf_obj_do_get(const struct filename *pathname,
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enum bpf_type *type)
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{
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struct inode *inode;
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struct path path;
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void *raw;
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int ret;
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ret = kern_path(pathname->name, LOOKUP_FOLLOW, &path);
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if (ret)
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return ERR_PTR(ret);
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inode = d_backing_inode(path.dentry);
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ret = inode_permission(inode, MAY_WRITE);
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if (ret)
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goto out;
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ret = bpf_inode_type(inode, type);
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if (ret)
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goto out;
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raw = bpf_any_get(inode->i_private, *type);
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touch_atime(&path);
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path_put(&path);
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return raw;
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out:
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path_put(&path);
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return ERR_PTR(ret);
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}
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int bpf_obj_get_user(const char __user *pathname)
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{
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enum bpf_type type = BPF_TYPE_UNSPEC;
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struct filename *pname;
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int ret = -ENOENT;
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void *raw;
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pname = getname(pathname);
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if (IS_ERR(pname))
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return PTR_ERR(pname);
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raw = bpf_obj_do_get(pname, &type);
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if (IS_ERR(raw)) {
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ret = PTR_ERR(raw);
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goto out;
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}
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if (type == BPF_TYPE_PROG)
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ret = bpf_prog_new_fd(raw);
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else if (type == BPF_TYPE_MAP)
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ret = bpf_map_new_fd(raw);
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else
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goto out;
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if (ret < 0)
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bpf_any_put(raw, type);
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out:
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putname(pname);
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return ret;
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}
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static void bpf_evict_inode(struct inode *inode)
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{
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enum bpf_type type;
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truncate_inode_pages_final(&inode->i_data);
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clear_inode(inode);
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if (!bpf_inode_type(inode, &type))
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bpf_any_put(inode->i_private, type);
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}
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static const struct super_operations bpf_super_ops = {
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.statfs = simple_statfs,
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.drop_inode = generic_delete_inode,
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.evict_inode = bpf_evict_inode,
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};
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static int bpf_fill_super(struct super_block *sb, void *data, int silent)
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{
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static struct tree_descr bpf_rfiles[] = { { "" } };
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struct inode *inode;
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int ret;
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ret = simple_fill_super(sb, BPF_FS_MAGIC, bpf_rfiles);
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if (ret)
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return ret;
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sb->s_op = &bpf_super_ops;
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inode = sb->s_root->d_inode;
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inode->i_op = &bpf_dir_iops;
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inode->i_mode &= ~S_IALLUGO;
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inode->i_mode |= S_ISVTX | S_IRWXUGO;
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return 0;
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}
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static struct dentry *bpf_mount(struct file_system_type *type, int flags,
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const char *dev_name, void *data)
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{
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return mount_ns(type, flags, current->nsproxy->mnt_ns, bpf_fill_super);
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}
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static struct file_system_type bpf_fs_type = {
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.owner = THIS_MODULE,
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.name = "bpf",
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.mount = bpf_mount,
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.kill_sb = kill_litter_super,
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.fs_flags = FS_USERNS_MOUNT,
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};
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MODULE_ALIAS_FS("bpf");
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static int __init bpf_init(void)
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{
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int ret;
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ret = sysfs_create_mount_point(fs_kobj, "bpf");
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if (ret)
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return ret;
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ret = register_filesystem(&bpf_fs_type);
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if (ret)
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sysfs_remove_mount_point(fs_kobj, "bpf");
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return ret;
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}
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fs_initcall(bpf_init);
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