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vfs: add missing checks to copy_file_range

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Like the clone and dedupe interfaces we've recently fixed, the
copy_file_range() implementation is missing basic sanity, limits and
boundary condition tests on the parameters that are passed to it
from userspace. Create a new "generic_copy_file_checks()" function
modelled on the generic_remap_checks() function to provide this
missing functionality.

[Amir] Shorten copy length instead of checking pos_in limits
because input file size already abides by the limits.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Amir Goldstein 2019-06-05 08:04:49 -07:00 committed by Darrick J. Wong
parent 646955cd54
commit 96e6e8f4a6
3 changed files with 58 additions and 1 deletions
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3
fs/read_write.c
View File

@ -1626,7 +1626,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
return -EXDEV;
ret = generic_file_rw_checks(file_in, file_out);
ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
flags);
if (unlikely(ret))
return ret;

3
include/linux/fs.h
View File

@ -3050,6 +3050,9 @@ extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
loff_t *count, unsigned int remap_flags);
extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
extern int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
size_t *count, unsigned int flags);
extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);

53
mm/filemap.c
View File

@ -3056,6 +3056,59 @@ int generic_file_rw_checks(struct file *file_in, struct file *file_out)
return 0;
}
/*
* Performs necessary checks before doing a file copy
*
* Can adjust amount of bytes to copy via @req_count argument.
* Returns appropriate error code that caller should return or
* zero in case the copy should be allowed.
*/
int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
size_t *req_count, unsigned int flags)
{
struct inode *inode_in = file_inode(file_in);
struct inode *inode_out = file_inode(file_out);
uint64_t count = *req_count;
loff_t size_in;
int ret;
ret = generic_file_rw_checks(file_in, file_out);
if (ret)
return ret;
/* Don't touch certain kinds of inodes */
if (IS_IMMUTABLE(inode_out))
return -EPERM;
if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
return -ETXTBSY;
/* Ensure offsets don't wrap. */
if (pos_in + count < pos_in || pos_out + count < pos_out)
return -EOVERFLOW;
/* Shorten the copy to EOF */
size_in = i_size_read(inode_in);
if (pos_in >= size_in)
count = 0;
else
count = min(count, size_in - (uint64_t)pos_in);
ret = generic_write_check_limits(file_out, pos_out, &count);
if (ret)
return ret;
/* Don't allow overlapped copying within the same file. */
if (inode_in == inode_out &&
pos_out + count > pos_in &&
pos_out < pos_in + count)
return -EINVAL;
*req_count = count;
return 0;
}
int pagecache_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)