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remap_range: merge do_clone_file_range() into vfs_clone_file_range() 

commit dfad37051a ("remap_range: move permission hooks out of
do_clone_file_range()") moved the permission hooks from
do_clone_file_range() out to its caller vfs_clone_file_range(),
but left all the fast sanity checks in do_clone_file_range().

This makes the expensive security hooks be called in situations
that they would not have been called before (e.g. fs does not support
clone).

The only reason for the do_clone_file_range() helper was that overlayfs
did not use to be able to call vfs_clone_file_range() from copy up
context with sb_writers lock held.  However, since commit c63e56a4a6
("ovl: do not open/llseek lower file with upper sb_writers held"),
overlayfs just uses an open coded version of vfs_clone_file_range().

Merge_clone_file_range() into vfs_clone_file_range(), restoring the
original order of checks as it was before the regressing commit and adapt
the overlayfs code to call vfs_clone_file_range() before the permission
hooks that were added by commit ca7ab48240 ("ovl: add permission hooks
outside of do_splice_direct()").

Note that in the merge of do_clone_file_range(), the file_start_write()
context was reduced to cover ->remap_file_range() without holding it
over the permission hooks, which was the reason for doing the regressing
commit in the first place.

Reported-and-tested-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202401312229.eddeb9a6-oliver.sang@intel.com
Fixes: dfad37051a ("remap_range: move permission hooks out of do_clone_file_range()")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20240202102258.1582671-1-amir73il@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Amir Goldstein 2024-02-02 12:22:58 +02:00 committed by Christian Brauner
parent 6613476e22
commit 853b8d7597
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
3 changed files with 15 additions and 33 deletions
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14
fs/overlayfs/copy_up.c
View File

@ -265,20 +265,18 @@ static int ovl_copy_up_file(struct ovl_fs *ofs, struct dentry *dentry,
if (IS_ERR(old_file))
return PTR_ERR(old_file);
/* Try to use clone_file_range to clone up within the same fs */
cloned = vfs_clone_file_range(old_file, 0, new_file, 0, len, 0);
if (cloned == len)
goto out_fput;
/* Couldn't clone, so now we try to copy the data */
error = rw_verify_area(READ, old_file, &old_pos, len);
if (!error)
error = rw_verify_area(WRITE, new_file, &new_pos, len);
if (error)
goto out_fput;
/* Try to use clone_file_range to clone up within the same fs */
ovl_start_write(dentry);
cloned = do_clone_file_range(old_file, 0, new_file, 0, len, 0);
ovl_end_write(dentry);
if (cloned == len)
goto out_fput;
/* Couldn't clone, so now we try to copy the data */
/* Check if lower fs supports seek operation */
if (old_file->f_mode & FMODE_LSEEK)
skip_hole = true;

31
fs/remap_range.c
View File

@ -373,9 +373,9 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
}
EXPORT_SYMBOL(generic_remap_file_range_prep);
loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
loff_t len, unsigned int remap_flags)
loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
loff_t len, unsigned int remap_flags)
{
loff_t ret;
@ -391,23 +391,6 @@ loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
if (!file_in->f_op->remap_file_range)
return -EOPNOTSUPP;
ret = file_in->f_op->remap_file_range(file_in, pos_in,
file_out, pos_out, len, remap_flags);
if (ret < 0)
return ret;
fsnotify_access(file_in);
fsnotify_modify(file_out);
return ret;
}
EXPORT_SYMBOL(do_clone_file_range);
loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
loff_t len, unsigned int remap_flags)
{
loff_t ret;
ret = remap_verify_area(file_in, pos_in, len, false);
if (ret)
return ret;
@ -417,10 +400,14 @@ loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
return ret;
file_start_write(file_out);
ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len,
remap_flags);
ret = file_in->f_op->remap_file_range(file_in, pos_in,
file_out, pos_out, len, remap_flags);
file_end_write(file_out);
if (ret < 0)
return ret;
fsnotify_access(file_in);
fsnotify_modify(file_out);
return ret;
}
EXPORT_SYMBOL(vfs_clone_file_range);

3
include/linux/fs.h
View File

@ -2101,9 +2101,6 @@ int __generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
loff_t *count, unsigned int remap_flags);
extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
loff_t len, unsigned int remap_flags);
extern loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
loff_t len, unsigned int remap_flags);