linux/fs/vboxsf/utils.c
Christian Brauner 549c729771
fs: make helpers idmap mount aware
Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.

As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.

Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-24 14:27:20 +01:00

553 lines
12 KiB
C

// SPDX-License-Identifier: MIT
/*
* VirtualBox Guest Shared Folders support: Utility functions.
* Mainly conversion from/to VirtualBox/Linux data structures.
*
* Copyright (C) 2006-2018 Oracle Corporation
*/
#include <linux/namei.h>
#include <linux/nls.h>
#include <linux/sizes.h>
#include <linux/vfs.h>
#include "vfsmod.h"
struct inode *vboxsf_new_inode(struct super_block *sb)
{
struct vboxsf_sbi *sbi = VBOXSF_SBI(sb);
struct inode *inode;
unsigned long flags;
int cursor, ret;
u32 gen;
inode = new_inode(sb);
if (!inode)
return ERR_PTR(-ENOMEM);
idr_preload(GFP_KERNEL);
spin_lock_irqsave(&sbi->ino_idr_lock, flags);
cursor = idr_get_cursor(&sbi->ino_idr);
ret = idr_alloc_cyclic(&sbi->ino_idr, inode, 1, 0, GFP_ATOMIC);
if (ret >= 0 && ret < cursor)
sbi->next_generation++;
gen = sbi->next_generation;
spin_unlock_irqrestore(&sbi->ino_idr_lock, flags);
idr_preload_end();
if (ret < 0) {
iput(inode);
return ERR_PTR(ret);
}
inode->i_ino = ret;
inode->i_generation = gen;
return inode;
}
/* set [inode] attributes based on [info], uid/gid based on [sbi] */
void vboxsf_init_inode(struct vboxsf_sbi *sbi, struct inode *inode,
const struct shfl_fsobjinfo *info)
{
const struct shfl_fsobjattr *attr;
s64 allocated;
int mode;
attr = &info->attr;
#define mode_set(r) ((attr->mode & (SHFL_UNIX_##r)) ? (S_##r) : 0)
mode = mode_set(IRUSR);
mode |= mode_set(IWUSR);
mode |= mode_set(IXUSR);
mode |= mode_set(IRGRP);
mode |= mode_set(IWGRP);
mode |= mode_set(IXGRP);
mode |= mode_set(IROTH);
mode |= mode_set(IWOTH);
mode |= mode_set(IXOTH);
#undef mode_set
/* We use the host-side values for these */
inode->i_flags |= S_NOATIME | S_NOCMTIME;
inode->i_mapping->a_ops = &vboxsf_reg_aops;
if (SHFL_IS_DIRECTORY(attr->mode)) {
inode->i_mode = sbi->o.dmode_set ? sbi->o.dmode : mode;
inode->i_mode &= ~sbi->o.dmask;
inode->i_mode |= S_IFDIR;
inode->i_op = &vboxsf_dir_iops;
inode->i_fop = &vboxsf_dir_fops;
/*
* XXX: this probably should be set to the number of entries
* in the directory plus two (. ..)
*/
set_nlink(inode, 1);
} else if (SHFL_IS_SYMLINK(attr->mode)) {
inode->i_mode = sbi->o.fmode_set ? sbi->o.fmode : mode;
inode->i_mode &= ~sbi->o.fmask;
inode->i_mode |= S_IFLNK;
inode->i_op = &vboxsf_lnk_iops;
set_nlink(inode, 1);
} else {
inode->i_mode = sbi->o.fmode_set ? sbi->o.fmode : mode;
inode->i_mode &= ~sbi->o.fmask;
inode->i_mode |= S_IFREG;
inode->i_op = &vboxsf_reg_iops;
inode->i_fop = &vboxsf_reg_fops;
set_nlink(inode, 1);
}
inode->i_uid = sbi->o.uid;
inode->i_gid = sbi->o.gid;
inode->i_size = info->size;
inode->i_blkbits = 12;
/* i_blocks always in units of 512 bytes! */
allocated = info->allocated + 511;
do_div(allocated, 512);
inode->i_blocks = allocated;
inode->i_atime = ns_to_timespec64(
info->access_time.ns_relative_to_unix_epoch);
inode->i_ctime = ns_to_timespec64(
info->change_time.ns_relative_to_unix_epoch);
inode->i_mtime = ns_to_timespec64(
info->modification_time.ns_relative_to_unix_epoch);
}
int vboxsf_create_at_dentry(struct dentry *dentry,
struct shfl_createparms *params)
{
struct vboxsf_sbi *sbi = VBOXSF_SBI(dentry->d_sb);
struct shfl_string *path;
int err;
path = vboxsf_path_from_dentry(sbi, dentry);
if (IS_ERR(path))
return PTR_ERR(path);
err = vboxsf_create(sbi->root, path, params);
__putname(path);
return err;
}
int vboxsf_stat(struct vboxsf_sbi *sbi, struct shfl_string *path,
struct shfl_fsobjinfo *info)
{
struct shfl_createparms params = {};
int err;
params.handle = SHFL_HANDLE_NIL;
params.create_flags = SHFL_CF_LOOKUP | SHFL_CF_ACT_FAIL_IF_NEW;
err = vboxsf_create(sbi->root, path, &params);
if (err)
return err;
if (params.result != SHFL_FILE_EXISTS)
return -ENOENT;
if (info)
*info = params.info;
return 0;
}
int vboxsf_stat_dentry(struct dentry *dentry, struct shfl_fsobjinfo *info)
{
struct vboxsf_sbi *sbi = VBOXSF_SBI(dentry->d_sb);
struct shfl_string *path;
int err;
path = vboxsf_path_from_dentry(sbi, dentry);
if (IS_ERR(path))
return PTR_ERR(path);
err = vboxsf_stat(sbi, path, info);
__putname(path);
return err;
}
int vboxsf_inode_revalidate(struct dentry *dentry)
{
struct vboxsf_sbi *sbi;
struct vboxsf_inode *sf_i;
struct shfl_fsobjinfo info;
struct timespec64 prev_mtime;
struct inode *inode;
int err;
if (!dentry || !d_really_is_positive(dentry))
return -EINVAL;
inode = d_inode(dentry);
prev_mtime = inode->i_mtime;
sf_i = VBOXSF_I(inode);
sbi = VBOXSF_SBI(dentry->d_sb);
if (!sf_i->force_restat) {
if (time_before(jiffies, dentry->d_time + sbi->o.ttl))
return 0;
}
err = vboxsf_stat_dentry(dentry, &info);
if (err)
return err;
dentry->d_time = jiffies;
sf_i->force_restat = 0;
vboxsf_init_inode(sbi, inode, &info);
/*
* If the file was changed on the host side we need to invalidate the
* page-cache for it. Note this also gets triggered by our own writes,
* this is unavoidable.
*/
if (timespec64_compare(&inode->i_mtime, &prev_mtime) > 0)
invalidate_inode_pages2(inode->i_mapping);
return 0;
}
int vboxsf_getattr(struct user_namespace *mnt_userns, const struct path *path,
struct kstat *kstat, u32 request_mask, unsigned int flags)
{
int err;
struct dentry *dentry = path->dentry;
struct inode *inode = d_inode(dentry);
struct vboxsf_inode *sf_i = VBOXSF_I(inode);
switch (flags & AT_STATX_SYNC_TYPE) {
case AT_STATX_DONT_SYNC:
err = 0;
break;
case AT_STATX_FORCE_SYNC:
sf_i->force_restat = 1;
fallthrough;
default:
err = vboxsf_inode_revalidate(dentry);
}
if (err)
return err;
generic_fillattr(&init_user_ns, d_inode(dentry), kstat);
return 0;
}
int vboxsf_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
struct iattr *iattr)
{
struct vboxsf_inode *sf_i = VBOXSF_I(d_inode(dentry));
struct vboxsf_sbi *sbi = VBOXSF_SBI(dentry->d_sb);
struct shfl_createparms params = {};
struct shfl_fsobjinfo info = {};
u32 buf_len;
int err;
params.handle = SHFL_HANDLE_NIL;
params.create_flags = SHFL_CF_ACT_OPEN_IF_EXISTS |
SHFL_CF_ACT_FAIL_IF_NEW |
SHFL_CF_ACCESS_ATTR_WRITE;
/* this is at least required for Posix hosts */
if (iattr->ia_valid & ATTR_SIZE)
params.create_flags |= SHFL_CF_ACCESS_WRITE;
err = vboxsf_create_at_dentry(dentry, &params);
if (err || params.result != SHFL_FILE_EXISTS)
return err ? err : -ENOENT;
#define mode_set(r) ((iattr->ia_mode & (S_##r)) ? SHFL_UNIX_##r : 0)
/*
* Setting the file size and setting the other attributes has to
* be handled separately.
*/
if (iattr->ia_valid & (ATTR_MODE | ATTR_ATIME | ATTR_MTIME)) {
if (iattr->ia_valid & ATTR_MODE) {
info.attr.mode = mode_set(IRUSR);
info.attr.mode |= mode_set(IWUSR);
info.attr.mode |= mode_set(IXUSR);
info.attr.mode |= mode_set(IRGRP);
info.attr.mode |= mode_set(IWGRP);
info.attr.mode |= mode_set(IXGRP);
info.attr.mode |= mode_set(IROTH);
info.attr.mode |= mode_set(IWOTH);
info.attr.mode |= mode_set(IXOTH);
if (iattr->ia_mode & S_IFDIR)
info.attr.mode |= SHFL_TYPE_DIRECTORY;
else
info.attr.mode |= SHFL_TYPE_FILE;
}
if (iattr->ia_valid & ATTR_ATIME)
info.access_time.ns_relative_to_unix_epoch =
timespec64_to_ns(&iattr->ia_atime);
if (iattr->ia_valid & ATTR_MTIME)
info.modification_time.ns_relative_to_unix_epoch =
timespec64_to_ns(&iattr->ia_mtime);
/*
* Ignore ctime (inode change time) as it can't be set
* from userland anyway.
*/
buf_len = sizeof(info);
err = vboxsf_fsinfo(sbi->root, params.handle,
SHFL_INFO_SET | SHFL_INFO_FILE, &buf_len,
&info);
if (err) {
vboxsf_close(sbi->root, params.handle);
return err;
}
/* the host may have given us different attr then requested */
sf_i->force_restat = 1;
}
#undef mode_set
if (iattr->ia_valid & ATTR_SIZE) {
memset(&info, 0, sizeof(info));
info.size = iattr->ia_size;
buf_len = sizeof(info);
err = vboxsf_fsinfo(sbi->root, params.handle,
SHFL_INFO_SET | SHFL_INFO_SIZE, &buf_len,
&info);
if (err) {
vboxsf_close(sbi->root, params.handle);
return err;
}
/* the host may have given us different attr then requested */
sf_i->force_restat = 1;
}
vboxsf_close(sbi->root, params.handle);
/* Update the inode with what the host has actually given us. */
if (sf_i->force_restat)
vboxsf_inode_revalidate(dentry);
return 0;
}
/*
* [dentry] contains string encoded in coding system that corresponds
* to [sbi]->nls, we must convert it to UTF8 here.
* Returns a shfl_string allocated through __getname (must be freed using
* __putname), or an ERR_PTR on error.
*/
struct shfl_string *vboxsf_path_from_dentry(struct vboxsf_sbi *sbi,
struct dentry *dentry)
{
struct shfl_string *shfl_path;
int path_len, out_len, nb;
char *buf, *path;
wchar_t uni;
u8 *out;
buf = __getname();
if (!buf)
return ERR_PTR(-ENOMEM);
path = dentry_path_raw(dentry, buf, PATH_MAX);
if (IS_ERR(path)) {
__putname(buf);
return ERR_CAST(path);
}
path_len = strlen(path);
if (sbi->nls) {
shfl_path = __getname();
if (!shfl_path) {
__putname(buf);
return ERR_PTR(-ENOMEM);
}
out = shfl_path->string.utf8;
out_len = PATH_MAX - SHFLSTRING_HEADER_SIZE - 1;
while (path_len) {
nb = sbi->nls->char2uni(path, path_len, &uni);
if (nb < 0) {
__putname(shfl_path);
__putname(buf);
return ERR_PTR(-EINVAL);
}
path += nb;
path_len -= nb;
nb = utf32_to_utf8(uni, out, out_len);
if (nb < 0) {
__putname(shfl_path);
__putname(buf);
return ERR_PTR(-ENAMETOOLONG);
}
out += nb;
out_len -= nb;
}
*out = 0;
shfl_path->length = out - shfl_path->string.utf8;
shfl_path->size = shfl_path->length + 1;
__putname(buf);
} else {
if ((SHFLSTRING_HEADER_SIZE + path_len + 1) > PATH_MAX) {
__putname(buf);
return ERR_PTR(-ENAMETOOLONG);
}
/*
* dentry_path stores the name at the end of buf, but the
* shfl_string string we return must be properly aligned.
*/
shfl_path = (struct shfl_string *)buf;
memmove(shfl_path->string.utf8, path, path_len);
shfl_path->string.utf8[path_len] = 0;
shfl_path->length = path_len;
shfl_path->size = path_len + 1;
}
return shfl_path;
}
int vboxsf_nlscpy(struct vboxsf_sbi *sbi, char *name, size_t name_bound_len,
const unsigned char *utf8_name, size_t utf8_len)
{
const char *in;
char *out;
size_t out_len;
size_t out_bound_len;
size_t in_bound_len;
in = utf8_name;
in_bound_len = utf8_len;
out = name;
out_len = 0;
/* Reserve space for terminating 0 */
out_bound_len = name_bound_len - 1;
while (in_bound_len) {
int nb;
unicode_t uni;
nb = utf8_to_utf32(in, in_bound_len, &uni);
if (nb < 0)
return -EINVAL;
in += nb;
in_bound_len -= nb;
nb = sbi->nls->uni2char(uni, out, out_bound_len);
if (nb < 0)
return nb;
out += nb;
out_bound_len -= nb;
out_len += nb;
}
*out = 0;
return 0;
}
static struct vboxsf_dir_buf *vboxsf_dir_buf_alloc(struct list_head *list)
{
struct vboxsf_dir_buf *b;
b = kmalloc(sizeof(*b), GFP_KERNEL);
if (!b)
return NULL;
b->buf = kmalloc(DIR_BUFFER_SIZE, GFP_KERNEL);
if (!b->buf) {
kfree(b);
return NULL;
}
b->entries = 0;
b->used = 0;
b->free = DIR_BUFFER_SIZE;
list_add(&b->head, list);
return b;
}
static void vboxsf_dir_buf_free(struct vboxsf_dir_buf *b)
{
list_del(&b->head);
kfree(b->buf);
kfree(b);
}
struct vboxsf_dir_info *vboxsf_dir_info_alloc(void)
{
struct vboxsf_dir_info *p;
p = kmalloc(sizeof(*p), GFP_KERNEL);
if (!p)
return NULL;
INIT_LIST_HEAD(&p->info_list);
return p;
}
void vboxsf_dir_info_free(struct vboxsf_dir_info *p)
{
struct list_head *list, *pos, *tmp;
list = &p->info_list;
list_for_each_safe(pos, tmp, list) {
struct vboxsf_dir_buf *b;
b = list_entry(pos, struct vboxsf_dir_buf, head);
vboxsf_dir_buf_free(b);
}
kfree(p);
}
int vboxsf_dir_read_all(struct vboxsf_sbi *sbi, struct vboxsf_dir_info *sf_d,
u64 handle)
{
struct vboxsf_dir_buf *b;
u32 entries, size;
int err = 0;
void *buf;
/* vboxsf_dirinfo returns 1 on end of dir */
while (err == 0) {
b = vboxsf_dir_buf_alloc(&sf_d->info_list);
if (!b) {
err = -ENOMEM;
break;
}
buf = b->buf;
size = b->free;
err = vboxsf_dirinfo(sbi->root, handle, NULL, 0, 0,
&size, buf, &entries);
if (err < 0)
break;
b->entries += entries;
b->free -= size;
b->used += size;
}
if (b && b->used == 0)
vboxsf_dir_buf_free(b);
/* -EILSEQ means the host could not translate a filename, ignore */
if (err > 0 || err == -EILSEQ)
err = 0;
return err;
}