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e67fe63341
Convert to struct mnt_idmap.
Remove legacy file_mnt_user_ns() and mnt_user_ns().
Last cycle we merged the necessary infrastructure in
256c8aed2b
("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
570 lines
14 KiB
C
570 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/slab.h>
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#include <linux/stat.h>
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#include <linux/sched/xacct.h>
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#include <linux/fcntl.h>
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#include <linux/file.h>
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#include <linux/uio.h>
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#include <linux/fsnotify.h>
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#include <linux/security.h>
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#include <linux/export.h>
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#include <linux/syscalls.h>
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#include <linux/pagemap.h>
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#include <linux/splice.h>
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#include <linux/compat.h>
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#include <linux/mount.h>
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#include <linux/fs.h>
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#include <linux/dax.h>
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#include "internal.h"
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#include <linux/uaccess.h>
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#include <asm/unistd.h>
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/*
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* Performs necessary checks before doing a clone.
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*
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* Can adjust amount of bytes to clone via @req_count argument.
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* Returns appropriate error code that caller should return or
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* zero in case the clone should be allowed.
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*/
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static int generic_remap_checks(struct file *file_in, loff_t pos_in,
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struct file *file_out, loff_t pos_out,
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loff_t *req_count, unsigned int remap_flags)
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{
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struct inode *inode_in = file_in->f_mapping->host;
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struct inode *inode_out = file_out->f_mapping->host;
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uint64_t count = *req_count;
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uint64_t bcount;
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loff_t size_in, size_out;
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loff_t bs = inode_out->i_sb->s_blocksize;
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int ret;
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/* The start of both ranges must be aligned to an fs block. */
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if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs))
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return -EINVAL;
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/* Ensure offsets don't wrap. */
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if (pos_in + count < pos_in || pos_out + count < pos_out)
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return -EINVAL;
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size_in = i_size_read(inode_in);
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size_out = i_size_read(inode_out);
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/* Dedupe requires both ranges to be within EOF. */
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if ((remap_flags & REMAP_FILE_DEDUP) &&
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(pos_in >= size_in || pos_in + count > size_in ||
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pos_out >= size_out || pos_out + count > size_out))
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return -EINVAL;
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/* Ensure the infile range is within the infile. */
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if (pos_in >= size_in)
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return -EINVAL;
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count = min(count, size_in - (uint64_t)pos_in);
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ret = generic_write_check_limits(file_out, pos_out, &count);
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if (ret)
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return ret;
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/*
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* If the user wanted us to link to the infile's EOF, round up to the
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* next block boundary for this check.
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*
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* Otherwise, make sure the count is also block-aligned, having
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* already confirmed the starting offsets' block alignment.
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*/
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if (pos_in + count == size_in &&
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(!(remap_flags & REMAP_FILE_DEDUP) || pos_out + count == size_out)) {
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bcount = ALIGN(size_in, bs) - pos_in;
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} else {
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if (!IS_ALIGNED(count, bs))
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count = ALIGN_DOWN(count, bs);
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bcount = count;
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}
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/* Don't allow overlapped cloning within the same file. */
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if (inode_in == inode_out &&
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pos_out + bcount > pos_in &&
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pos_out < pos_in + bcount)
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return -EINVAL;
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/*
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* We shortened the request but the caller can't deal with that, so
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* bounce the request back to userspace.
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*/
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if (*req_count != count && !(remap_flags & REMAP_FILE_CAN_SHORTEN))
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return -EINVAL;
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*req_count = count;
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return 0;
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}
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static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
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bool write)
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{
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if (unlikely(pos < 0 || len < 0))
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return -EINVAL;
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if (unlikely((loff_t) (pos + len) < 0))
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return -EINVAL;
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return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
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}
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/*
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* Ensure that we don't remap a partial EOF block in the middle of something
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* else. Assume that the offsets have already been checked for block
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* alignment.
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*
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* For clone we only link a partial EOF block above or at the destination file's
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* EOF. For deduplication we accept a partial EOF block only if it ends at the
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* destination file's EOF (can not link it into the middle of a file).
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*
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* Shorten the request if possible.
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*/
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static int generic_remap_check_len(struct inode *inode_in,
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struct inode *inode_out,
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loff_t pos_out,
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loff_t *len,
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unsigned int remap_flags)
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{
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u64 blkmask = i_blocksize(inode_in) - 1;
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loff_t new_len = *len;
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if ((*len & blkmask) == 0)
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return 0;
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if (pos_out + *len < i_size_read(inode_out))
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new_len &= ~blkmask;
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if (new_len == *len)
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return 0;
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if (remap_flags & REMAP_FILE_CAN_SHORTEN) {
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*len = new_len;
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return 0;
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}
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return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
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}
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/* Read a page's worth of file data into the page cache. */
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static struct folio *vfs_dedupe_get_folio(struct file *file, loff_t pos)
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{
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return read_mapping_folio(file->f_mapping, pos >> PAGE_SHIFT, file);
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}
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/*
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* Lock two folios, ensuring that we lock in offset order if the folios
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* are from the same file.
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*/
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static void vfs_lock_two_folios(struct folio *folio1, struct folio *folio2)
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{
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/* Always lock in order of increasing index. */
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if (folio1->index > folio2->index)
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swap(folio1, folio2);
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folio_lock(folio1);
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if (folio1 != folio2)
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folio_lock(folio2);
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}
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/* Unlock two folios, being careful not to unlock the same folio twice. */
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static void vfs_unlock_two_folios(struct folio *folio1, struct folio *folio2)
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{
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folio_unlock(folio1);
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if (folio1 != folio2)
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folio_unlock(folio2);
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}
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/*
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* Compare extents of two files to see if they are the same.
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* Caller must have locked both inodes to prevent write races.
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*/
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static int vfs_dedupe_file_range_compare(struct file *src, loff_t srcoff,
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struct file *dest, loff_t dstoff,
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loff_t len, bool *is_same)
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{
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bool same = true;
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int error = -EINVAL;
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while (len) {
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struct folio *src_folio, *dst_folio;
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void *src_addr, *dst_addr;
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loff_t cmp_len = min(PAGE_SIZE - offset_in_page(srcoff),
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PAGE_SIZE - offset_in_page(dstoff));
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cmp_len = min(cmp_len, len);
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if (cmp_len <= 0)
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goto out_error;
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src_folio = vfs_dedupe_get_folio(src, srcoff);
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if (IS_ERR(src_folio)) {
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error = PTR_ERR(src_folio);
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goto out_error;
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}
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dst_folio = vfs_dedupe_get_folio(dest, dstoff);
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if (IS_ERR(dst_folio)) {
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error = PTR_ERR(dst_folio);
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folio_put(src_folio);
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goto out_error;
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}
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vfs_lock_two_folios(src_folio, dst_folio);
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/*
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* Now that we've locked both folios, make sure they're still
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* mapped to the file data we're interested in. If not,
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* someone is invalidating pages on us and we lose.
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*/
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if (!folio_test_uptodate(src_folio) || !folio_test_uptodate(dst_folio) ||
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src_folio->mapping != src->f_mapping ||
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dst_folio->mapping != dest->f_mapping) {
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same = false;
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goto unlock;
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}
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src_addr = kmap_local_folio(src_folio,
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offset_in_folio(src_folio, srcoff));
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dst_addr = kmap_local_folio(dst_folio,
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offset_in_folio(dst_folio, dstoff));
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flush_dcache_folio(src_folio);
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flush_dcache_folio(dst_folio);
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if (memcmp(src_addr, dst_addr, cmp_len))
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same = false;
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kunmap_local(dst_addr);
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kunmap_local(src_addr);
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unlock:
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vfs_unlock_two_folios(src_folio, dst_folio);
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folio_put(dst_folio);
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folio_put(src_folio);
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if (!same)
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break;
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srcoff += cmp_len;
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dstoff += cmp_len;
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len -= cmp_len;
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}
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*is_same = same;
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return 0;
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out_error:
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return error;
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}
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/*
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* Check that the two inodes are eligible for cloning, the ranges make
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* sense, and then flush all dirty data. Caller must ensure that the
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* inodes have been locked against any other modifications.
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*
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* If there's an error, then the usual negative error code is returned.
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* Otherwise returns 0 with *len set to the request length.
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*/
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int
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__generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
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struct file *file_out, loff_t pos_out,
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loff_t *len, unsigned int remap_flags,
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const struct iomap_ops *dax_read_ops)
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{
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struct inode *inode_in = file_inode(file_in);
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struct inode *inode_out = file_inode(file_out);
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bool same_inode = (inode_in == inode_out);
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int ret;
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/* Don't touch certain kinds of inodes */
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if (IS_IMMUTABLE(inode_out))
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return -EPERM;
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if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
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return -ETXTBSY;
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/* Don't reflink dirs, pipes, sockets... */
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if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
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return -EISDIR;
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if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
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return -EINVAL;
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/* Zero length dedupe exits immediately; reflink goes to EOF. */
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if (*len == 0) {
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loff_t isize = i_size_read(inode_in);
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if ((remap_flags & REMAP_FILE_DEDUP) || pos_in == isize)
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return 0;
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if (pos_in > isize)
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return -EINVAL;
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*len = isize - pos_in;
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if (*len == 0)
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return 0;
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}
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/* Check that we don't violate system file offset limits. */
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ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
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remap_flags);
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if (ret || *len == 0)
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return ret;
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/* Wait for the completion of any pending IOs on both files */
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inode_dio_wait(inode_in);
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if (!same_inode)
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inode_dio_wait(inode_out);
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ret = filemap_write_and_wait_range(inode_in->i_mapping,
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pos_in, pos_in + *len - 1);
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if (ret)
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return ret;
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ret = filemap_write_and_wait_range(inode_out->i_mapping,
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pos_out, pos_out + *len - 1);
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if (ret)
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return ret;
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/*
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* Check that the extents are the same.
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*/
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if (remap_flags & REMAP_FILE_DEDUP) {
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bool is_same = false;
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if (!IS_DAX(inode_in))
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ret = vfs_dedupe_file_range_compare(file_in, pos_in,
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file_out, pos_out, *len, &is_same);
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else if (dax_read_ops)
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ret = dax_dedupe_file_range_compare(inode_in, pos_in,
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inode_out, pos_out, *len, &is_same,
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dax_read_ops);
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else
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return -EINVAL;
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if (ret)
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return ret;
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if (!is_same)
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return -EBADE;
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}
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ret = generic_remap_check_len(inode_in, inode_out, pos_out, len,
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remap_flags);
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if (ret || *len == 0)
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return ret;
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/* If can't alter the file contents, we're done. */
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if (!(remap_flags & REMAP_FILE_DEDUP))
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ret = file_modified(file_out);
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return ret;
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}
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int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
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struct file *file_out, loff_t pos_out,
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loff_t *len, unsigned int remap_flags)
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{
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return __generic_remap_file_range_prep(file_in, pos_in, file_out,
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pos_out, len, remap_flags, NULL);
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}
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EXPORT_SYMBOL(generic_remap_file_range_prep);
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loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
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struct file *file_out, loff_t pos_out,
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loff_t len, unsigned int remap_flags)
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{
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loff_t ret;
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WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);
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if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
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return -EXDEV;
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ret = generic_file_rw_checks(file_in, file_out);
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if (ret < 0)
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return ret;
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if (!file_in->f_op->remap_file_range)
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return -EOPNOTSUPP;
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ret = remap_verify_area(file_in, pos_in, len, false);
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if (ret)
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return ret;
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ret = remap_verify_area(file_out, pos_out, len, true);
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if (ret)
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return ret;
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ret = file_in->f_op->remap_file_range(file_in, pos_in,
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file_out, pos_out, len, remap_flags);
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if (ret < 0)
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return ret;
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fsnotify_access(file_in);
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fsnotify_modify(file_out);
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return ret;
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}
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EXPORT_SYMBOL(do_clone_file_range);
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loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
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struct file *file_out, loff_t pos_out,
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loff_t len, unsigned int remap_flags)
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{
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loff_t ret;
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file_start_write(file_out);
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ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len,
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remap_flags);
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file_end_write(file_out);
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return ret;
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}
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EXPORT_SYMBOL(vfs_clone_file_range);
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/* Check whether we are allowed to dedupe the destination file */
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static bool allow_file_dedupe(struct file *file)
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{
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struct mnt_idmap *idmap = file_mnt_idmap(file);
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struct inode *inode = file_inode(file);
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if (capable(CAP_SYS_ADMIN))
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return true;
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if (file->f_mode & FMODE_WRITE)
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return true;
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if (vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode), current_fsuid()))
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return true;
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if (!inode_permission(idmap, inode, MAY_WRITE))
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return true;
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return false;
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}
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loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
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struct file *dst_file, loff_t dst_pos,
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loff_t len, unsigned int remap_flags)
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{
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loff_t ret;
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WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP |
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REMAP_FILE_CAN_SHORTEN));
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ret = mnt_want_write_file(dst_file);
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if (ret)
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return ret;
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/*
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* This is redundant if called from vfs_dedupe_file_range(), but other
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* callers need it and it's not performance sesitive...
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*/
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ret = remap_verify_area(src_file, src_pos, len, false);
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if (ret)
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goto out_drop_write;
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ret = remap_verify_area(dst_file, dst_pos, len, true);
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if (ret)
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goto out_drop_write;
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ret = -EPERM;
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if (!allow_file_dedupe(dst_file))
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goto out_drop_write;
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ret = -EXDEV;
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if (file_inode(src_file)->i_sb != file_inode(dst_file)->i_sb)
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goto out_drop_write;
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ret = -EISDIR;
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if (S_ISDIR(file_inode(dst_file)->i_mode))
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goto out_drop_write;
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ret = -EINVAL;
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if (!dst_file->f_op->remap_file_range)
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goto out_drop_write;
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if (len == 0) {
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ret = 0;
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goto out_drop_write;
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}
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ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file,
|
|
dst_pos, len, remap_flags | REMAP_FILE_DEDUP);
|
|
out_drop_write:
|
|
mnt_drop_write_file(dst_file);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(vfs_dedupe_file_range_one);
|
|
|
|
int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
|
|
{
|
|
struct file_dedupe_range_info *info;
|
|
struct inode *src = file_inode(file);
|
|
u64 off;
|
|
u64 len;
|
|
int i;
|
|
int ret;
|
|
u16 count = same->dest_count;
|
|
loff_t deduped;
|
|
|
|
if (!(file->f_mode & FMODE_READ))
|
|
return -EINVAL;
|
|
|
|
if (same->reserved1 || same->reserved2)
|
|
return -EINVAL;
|
|
|
|
off = same->src_offset;
|
|
len = same->src_length;
|
|
|
|
if (S_ISDIR(src->i_mode))
|
|
return -EISDIR;
|
|
|
|
if (!S_ISREG(src->i_mode))
|
|
return -EINVAL;
|
|
|
|
if (!file->f_op->remap_file_range)
|
|
return -EOPNOTSUPP;
|
|
|
|
ret = remap_verify_area(file, off, len, false);
|
|
if (ret < 0)
|
|
return ret;
|
|
ret = 0;
|
|
|
|
if (off + len > i_size_read(src))
|
|
return -EINVAL;
|
|
|
|
/* Arbitrary 1G limit on a single dedupe request, can be raised. */
|
|
len = min_t(u64, len, 1 << 30);
|
|
|
|
/* pre-format output fields to sane values */
|
|
for (i = 0; i < count; i++) {
|
|
same->info[i].bytes_deduped = 0ULL;
|
|
same->info[i].status = FILE_DEDUPE_RANGE_SAME;
|
|
}
|
|
|
|
for (i = 0, info = same->info; i < count; i++, info++) {
|
|
struct fd dst_fd = fdget(info->dest_fd);
|
|
struct file *dst_file = dst_fd.file;
|
|
|
|
if (!dst_file) {
|
|
info->status = -EBADF;
|
|
goto next_loop;
|
|
}
|
|
|
|
if (info->reserved) {
|
|
info->status = -EINVAL;
|
|
goto next_fdput;
|
|
}
|
|
|
|
deduped = vfs_dedupe_file_range_one(file, off, dst_file,
|
|
info->dest_offset, len,
|
|
REMAP_FILE_CAN_SHORTEN);
|
|
if (deduped == -EBADE)
|
|
info->status = FILE_DEDUPE_RANGE_DIFFERS;
|
|
else if (deduped < 0)
|
|
info->status = deduped;
|
|
else
|
|
info->bytes_deduped = len;
|
|
|
|
next_fdput:
|
|
fdput(dst_fd);
|
|
next_loop:
|
|
if (fatal_signal_pending(current))
|
|
break;
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(vfs_dedupe_file_range);
|