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file-posix: specify expected filetypes

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Adjust each caller of raw_open_common to specify if they are expecting
host and character devices or not. Tighten expectations of file types upon
open in the common code and refuse types that are not expected.

This has two effects:

(1) Character and block devices are now considered deprecated for the
    'file' driver, which expects only S_IFREG, and
(2) no file-posix driver (file, host_cdrom, or host_device) can open
    directories now.

I don't think there's a legitimate reason to open directories as if
they were files. This prevents QEMU from opening and attempting to probe
a directory inode, which can break in exciting ways. One of those ways
is lseek on ext4/xfs, which will return 0x7fffffffffffffff as the file
size instead of EISDIR. This can coax QEMU into responding with a
confusing "file too big" instead of "Hey, that's not a file".

See: https://bugs.launchpad.net/qemu/+bug/1739304/
Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
John Snow 2018-07-10 13:00:40 -04:00 committed by Kevin Wolf
parent eb461485f4
commit 230ff73904
2 changed files with 37 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
block/file-posix.c
View File

@ -438,7 +438,8 @@ static QemuOptsList raw_runtime_opts = {
};
static int raw_open_common(BlockDriverState *bs, QDict *options,
int bdrv_flags, int open_flags, Error **errp)
int bdrv_flags, int open_flags,
bool device, Error **errp)
{
BDRVRawState *s = bs->opaque;
QemuOpts *opts;
@ -585,10 +586,32 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
error_setg_errno(errp, errno, "Could not stat file");
goto fail;
}
if (S_ISREG(st.st_mode)) {
s->discard_zeroes = true;
s->has_fallocate = true;
if (!device) {
if (S_ISBLK(st.st_mode)) {
warn_report("Opening a block device as a file using the '%s' "
"driver is deprecated", bs->drv->format_name);
} else if (S_ISCHR(st.st_mode)) {
warn_report("Opening a character device as a file using the '%s' "
"driver is deprecated", bs->drv->format_name);
} else if (!S_ISREG(st.st_mode)) {
error_setg(errp, "A regular file was expected by the '%s' driver, "
"but something else was given", bs->drv->format_name);
ret = -EINVAL;
goto fail;
} else {
s->discard_zeroes = true;
s->has_fallocate = true;
}
} else {
if (!(S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode))) {
error_setg(errp, "'%s' driver expects either "
"a character or block device", bs->drv->format_name);
ret = -EINVAL;
goto fail;
}
}
if (S_ISBLK(st.st_mode)) {
#ifdef BLKDISCARDZEROES
unsigned int arg;
@ -641,7 +664,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
BDRVRawState *s = bs->opaque;
s->type = FTYPE_FILE;
return raw_open_common(bs, options, flags, 0, errp);
return raw_open_common(bs, options, flags, 0, false, errp);
}
typedef enum {
@ -2939,7 +2962,7 @@ hdev_open_Mac_error:
s->type = FTYPE_FILE;
ret = raw_open_common(bs, options, flags, 0, &local_err);
ret = raw_open_common(bs, options, flags, 0, true, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
#if defined(__APPLE__) && defined(__MACH__)
@ -3170,7 +3193,7 @@ static int cdrom_open(BlockDriverState *bs, QDict *options, int flags,
s->type = FTYPE_CD;
/* open will not fail even if no CD is inserted, so add O_NONBLOCK */
return raw_open_common(bs, options, flags, O_NONBLOCK, errp);
return raw_open_common(bs, options, flags, O_NONBLOCK, true, errp);
}
static int cdrom_probe_device(const char *filename)
@ -3284,7 +3307,7 @@ static int cdrom_open(BlockDriverState *bs, QDict *options, int flags,
s->type = FTYPE_CD;
ret = raw_open_common(bs, options, flags, 0, &local_err);
ret = raw_open_common(bs, options, flags, 0, true, &local_err);
if (ret) {
error_propagate(errp, local_err);
return ret;

6
qemu-doc.texi
View File

@ -2969,6 +2969,12 @@ replacement since it is not needed anymore.
The @option{-enable-hax} option has been replaced by @option{-accel hax}.
Both options have been introduced in QEMU version 2.9.0.
@subsection -drive file=json:@{...@{'driver':'file'@}@} (since 3.0)
The 'file' driver for drives is no longer appropriate for character or host
devices and will only accept regular files (S_IFREG). The correct driver
for these file types is 'host_cdrom' or 'host_device' as appropriate.
@section QEMU Machine Protocol (QMP) commands
@subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)