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fs: move fiemap range validation into the file systems instances

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Replace fiemap_check_flags with a fiemap_prep helper that also takes the
inode and mapped range, and performs the sanity check and truncation
previously done in fiemap_check_range.  This way the validation is inside
the file system itself and thus properly works for the stacked overlayfs
case as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Link: https://lore.kernel.org/r/20200523073016.2944131-7-hch@lst.de
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Christoph Hellwig
2020-05-23 09:30:13 +02:00
committed by Theodore Ts'o
parent 2732881894
commit cddf8a2c4a
10 changed files with 47 additions and 54 deletions
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63
fs/ioctl.c
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@@ -149,61 +149,50 @@ int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
EXPORT_SYMBOL(fiemap_fill_next_extent);
/**
* fiemap_check_flags - check validity of requested flags for fiemap
* fiemap_prep - check validity of requested flags for fiemap
* @inode: Inode to operate on
* @fieinfo: Fiemap context passed into ->fiemap
* @fs_flags: Set of fiemap flags that the file system understands
* @start: Start of the mapped range
* @len: Length of the mapped range, can be truncated by this function.
* @supported_flags: Set of fiemap flags that the file system understands
*
* Called from file system ->fiemap callback. This will compute the
* intersection of valid fiemap flags and those that the fs supports. That
* value is then compared against the user supplied flags. In case of bad user
* flags, the invalid values will be written into the fieinfo structure, and
* -EBADR is returned, which tells ioctl_fiemap() to return those values to
* userspace. For this reason, a return code of -EBADR should be preserved.
* This function must be called from each ->fiemap instance to validate the
* fiemap request against the file system parameters.
*
* Returns 0 on success, -EBADR on bad flags.
* Returns 0 on success, or a negative error on failure.
*/
int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags)
int fiemap_prep(struct inode *inode, struct fiemap_extent_info *fieinfo,
u64 start, u64 *len, u32 supported_flags)
{
u64 maxbytes = inode->i_sb->s_maxbytes;
u32 incompat_flags;
incompat_flags = fieinfo->fi_flags & ~(FIEMAP_FLAGS_COMPAT & fs_flags);
if (incompat_flags) {
fieinfo->fi_flags = incompat_flags;
return -EBADR;
}
return 0;
}
EXPORT_SYMBOL(fiemap_check_flags);
static int fiemap_check_ranges(struct super_block *sb,
u64 start, u64 len, u64 *new_len)
{
u64 maxbytes = (u64) sb->s_maxbytes;
*new_len = len;
if (len == 0)
if (*len == 0)
return -EINVAL;
if (start > maxbytes)
return -EFBIG;
/*
* Shrink request scope to what the fs can actually handle.
*/
if (len > maxbytes || (maxbytes - len) < start)
*new_len = maxbytes - start;
if (*len > maxbytes || (maxbytes - *len) < start)
*len = maxbytes - start;
supported_flags &= FIEMAP_FLAGS_COMPAT;
incompat_flags = fieinfo->fi_flags & ~supported_flags;
if (incompat_flags) {
fieinfo->fi_flags = incompat_flags;
return -EBADR;
}
return 0;
}
EXPORT_SYMBOL(fiemap_prep);
static int ioctl_fiemap(struct file *filp, struct fiemap __user *ufiemap)
{
struct fiemap fiemap;
struct fiemap_extent_info fieinfo = { 0, };
struct inode *inode = file_inode(filp);
struct super_block *sb = inode->i_sb;
u64 len;
int error;
if (!inode->i_op->fiemap)
@@ -215,11 +204,6 @@ static int ioctl_fiemap(struct file *filp, struct fiemap __user *ufiemap)
if (fiemap.fm_extent_count > FIEMAP_MAX_EXTENTS)
return -EINVAL;
error = fiemap_check_ranges(sb, fiemap.fm_start, fiemap.fm_length,
&len);
if (error)
return error;
fieinfo.fi_flags = fiemap.fm_flags;
fieinfo.fi_extents_max = fiemap.fm_extent_count;
fieinfo.fi_extents_start = ufiemap->fm_extents;
@@ -232,7 +216,8 @@ static int ioctl_fiemap(struct file *filp, struct fiemap __user *ufiemap)
if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
filemap_write_and_wait(inode->i_mapping);
error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start, len);
error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start,
fiemap.fm_length);
fiemap.fm_flags = fieinfo.fi_flags;
fiemap.fm_mapped_extents = fieinfo.fi_extents_mapped;
if (copy_to_user(ufiemap, &fiemap, sizeof(fiemap)))
@@ -320,7 +305,7 @@ static int __generic_block_fiemap(struct inode *inode,
bool past_eof = false, whole_file = false;
int ret = 0;
ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC);
ret = fiemap_prep(inode, fieinfo, start, &len, FIEMAP_FLAG_SYNC);
if (ret)
return ret;