Factor out a path_umount helper that takes a struct path * instead of the
actual file name. This will allow to convert the init and devtmpfs code
to properly mount based on a kernel pointer instead of relying on the
implicit set_fs(KERNEL_DS) during early init.
Signed-off-by: Christoph Hellwig <[email protected]>
---
fs/namespace.c | 40 ++++++++++++++++++----------------------
1 file changed, 18 insertions(+), 22 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 6f8234f74bed90..43834b59eff6c3 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1706,36 +1706,19 @@ static inline bool may_mandlock(void)
}
#endif
-/*
- * Now umount can handle mount points as well as block devices.
- * This is important for filesystems which use unnamed block devices.
- *
- * We now support a flag for forced unmount like the other 'big iron'
- * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
- */
-
-int ksys_umount(char __user *name, int flags)
+static int path_umount(struct path *path, int flags)
{
- struct path path;
struct mount *mnt;
int retval;
- int lookup_flags = LOOKUP_MOUNTPOINT;
if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
return -EINVAL;
-
if (!may_mount())
return -EPERM;
- if (!(flags & UMOUNT_NOFOLLOW))
- lookup_flags |= LOOKUP_FOLLOW;
-
- retval = user_path_at(AT_FDCWD, name, lookup_flags, &path);
- if (retval)
- goto out;
- mnt = real_mount(path.mnt);
+ mnt = real_mount(path->mnt);
retval = -EINVAL;
- if (path.dentry != path.mnt->mnt_root)
+ if (path->dentry != path->mnt->mnt_root)
goto dput_and_out;
if (!check_mnt(mnt))
goto dput_and_out;
@@ -1748,12 +1731,25 @@ int ksys_umount(char __user *name, int flags)
retval = do_umount(mnt, flags);
dput_and_out:
/* we mustn't call path_put() as that would clear mnt_expiry_mark */
- dput(path.dentry);
+ dput(path->dentry);
mntput_no_expire(mnt);
-out:
return retval;
}
+int ksys_umount(char __user *name, int flags)
+{
+ int lookup_flags = LOOKUP_MOUNTPOINT;
+ struct path path;
+ int ret;
+
+ if (!(flags & UMOUNT_NOFOLLOW))
+ lookup_flags |= LOOKUP_FOLLOW;
+ ret = user_path_at(AT_FDCWD, name, lookup_flags, &path);
+ if (ret)
+ return ret;
+ return path_umount(&path, flags);
+}
+
SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
{
return ksys_umount(name, flags);
--
2.27.0
On Tue, 28 Jul 2020 at 22:04, Christoph Hellwig <[email protected]> wrote:
>
> Factor out a path_umount helper that takes a struct path * instead of the
> actual file name. This will allow to convert the init and devtmpfs code
> to properly mount based on a kernel pointer instead of relying on the
> implicit set_fs(KERNEL_DS) during early init.
>
> Signed-off-by: Christoph Hellwig <[email protected]>
> ---
> fs/namespace.c | 40 ++++++++++++++++++----------------------
> 1 file changed, 18 insertions(+), 22 deletions(-)
>
> diff --git a/fs/namespace.c b/fs/namespace.c
> index 6f8234f74bed90..43834b59eff6c3 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -1706,36 +1706,19 @@ static inline bool may_mandlock(void)
> }
> #endif
>
> -/*
> - * Now umount can handle mount points as well as block devices.
> - * This is important for filesystems which use unnamed block devices.
> - *
> - * We now support a flag for forced unmount like the other 'big iron'
> - * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
> - */
> -
> -int ksys_umount(char __user *name, int flags)
> +static int path_umount(struct path *path, int flags)
> {
> - struct path path;
> struct mount *mnt;
> int retval;
> - int lookup_flags = LOOKUP_MOUNTPOINT;
>
> if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
> return -EINVAL;
> -
> if (!may_mount())
> return -EPERM;
>
> - if (!(flags & UMOUNT_NOFOLLOW))
> - lookup_flags |= LOOKUP_FOLLOW;
> -
> - retval = user_path_at(AT_FDCWD, name, lookup_flags, &path);
> - if (retval)
> - goto out;
> - mnt = real_mount(path.mnt);
> + mnt = real_mount(path->mnt);
> retval = -EINVAL;
> - if (path.dentry != path.mnt->mnt_root)
> + if (path->dentry != path->mnt->mnt_root)
> goto dput_and_out;
> if (!check_mnt(mnt))
> goto dput_and_out;
> @@ -1748,12 +1731,25 @@ int ksys_umount(char __user *name, int flags)
> retval = do_umount(mnt, flags);
> dput_and_out:
> /* we mustn't call path_put() as that would clear mnt_expiry_mark */
> - dput(path.dentry);
> + dput(path->dentry);
> mntput_no_expire(mnt);
> -out:
> return retval;
> }
>
> +int ksys_umount(char __user *name, int flags)
> +{
> + int lookup_flags = LOOKUP_MOUNTPOINT;
> + struct path path;
> + int ret;
> +
> + if (!(flags & UMOUNT_NOFOLLOW))
> + lookup_flags |= LOOKUP_FOLLOW;
> + ret = user_path_at(AT_FDCWD, name, lookup_flags, &path);
> + if (ret)
> + return ret;
> + return path_umount(&path, flags);
> +}
> +
> SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
> {
> return ksys_umount(name, flags);
Regressions on linux next 20200803 tag kernel.
LTP syscalls test umount03 mount a path for testing and
umount failed and retired for 50 times and test exit with warning
and following test cases using that mount path failed.
LTP syscalls tests failed list,
* umount03
* umount2_01
* umount2_02
* umount2_03
* utime06
* copy_file_range01
Summary
------------------------------------------------------------------------
kernel: 5.8.0
git repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
git branch: master
git describe: next-20200803
Test details: https://qa-reports.linaro.org/lkft/linux-next-oe/build/next-20200803
------------------------------------------------------------------------
test failed log:
tst_device.c:262: INFO: Using test device LTP_DEV='/dev/loop0'
tst_mkfs.c:90: INFO: Formatting /dev/loop0 with ext2 opts='' extra opts=''
mke2fs 1.43.8 (1-Jan-2018)
tst_test.c:1246: INFO: Timeout per run is 0h 15m 00s
[ 870.449934] EXT4-fs (loop0): mounting ext2 file system using the
ext4 subsystem
[ 870.454338] EXT4-fs (loop0): mounted filesystem without journal. Opts: (null)
[ 870.456412] ext2 filesystem being mounted at
/tmp/ltp-YQrzWZNEEy/jVhqum/mntpoint supports timestamps until 2038
(0x7fffffff)
umount03.c:35: PASS: umount() fails as expected: EPERM (1)
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 1...
tst_device.c:388: INFO: Likely gvfsd-trash is probing newly mounted
fs, kill it to speed up tests.
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 2...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 3...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 4...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 5...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 6...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 7...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 8...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 9...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 10...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 11...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 12...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 13...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 14...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 15...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 16...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 17...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 18...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 19...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 20...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 21...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 22...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 23...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 24...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 25...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 26...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 27...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 28...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 29...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 30...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 31...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 32...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 33...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 34...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 35...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 36...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 37...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 38...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 39...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 40...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 41...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 42...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 43...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 44...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 45...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 46...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 47...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 48...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 49...
tst_device.c:384: INFO: umount('mntpoint') failed with EBUSY, try 50...
tst_device.c:394: WARN: Failed to umount('mntpoint') after 50 retries
tst_tmpdir.c:337: WARN: tst_rmdir: rmobj(/tmp/ltp-YQrzWZNEEy/jVhqum)
failed: remove(/tmp/ltp-YQrzWZNEEy/jVhqum/mntpoint) failed; errno=16:
EBUSY
Summary:
passed 1
failed 0
skipped 0
warnings 1
mke2fs 1.43.8 (1-Jan-2018)
/dev/loop0 is mounted; will not make a filesystem here!
umount2_01 0 TINFO : Using test device LTP_DEV='/dev/loop0'
umount2_01 0 TINFO : Formatting /dev/loop0 with ext2 opts='' extra opts=''
umount2_01 1 TBROK : tst_mkfs.c:103: umount2_01.c:81: mkfs.ext2
failed with 1
umount2_01 2 TBROK : tst_mkfs.c:103: Remaining cases broken
mke2fs 1.43.8 (1-Jan-2018)
/dev/loop0 is mounted; will not make a filesystem here!
umount2_02 0 TINFO : Using test device LTP_DEV='/dev/loop0'
umount2_02 0 TINFO : Formatting /dev/loop0 with ext2 opts='' extra opts=''
umount2_02 1 TBROK : tst_mkfs.c:103: umount2_02.c:121: mkfs.ext2
failed with 1
umount2_02 2 TBROK : tst_mkfs.c:103: Remaining cases broken
mke2fs 1.43.8 (1-Jan-2018)
/dev/loop0 is mounted; will not make a filesystem here!
umount2_03 0 TINFO : Using test device LTP_DEV='/dev/loop0'
umount2_03 0 TINFO : Formatting /dev/loop0 with ext2 opts='' extra opts=''
umount2_03 1 TBROK : tst_mkfs.c:103: umount2_03.c:101: mkfs.ext2
failed with 1
umount2_03 2 TBROK : tst_mkfs.c:103: Remaining cases broken
mke2fs 1.43.8 (1-Jan-2018)
/dev/loop0 is mounted; will not make a filesystem here!
utime06 0 TINFO : Using test device LTP_DEV='/dev/loop0'
utime06 0 TINFO : Formatting /dev/loop0 with ext2 opts='' extra opts=''
utime06 1 TBROK : tst_mkfs.c:103: utime06.c:122: mkfs.ext2 failed with 1
utime06 2 TBROK : tst_mkfs.c:103: Remaining cases broken
Steps to reproduce:
-------------------------
cd /opt/ltp
./runltp -s umount --> FAILS
Above command runs all umount tests.
Test case description,
Verify that umount(2) returns -1 and sets errno to EPERM if the user
is not the super-user.
Test case link,
https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/umount/umount03.c
full test log,
https://lkft.validation.linaro.org/scheduler/job/1642287
--
Linaro LKFT
https://lkft.linaro.org
On Thu, 6 Aug 2020 at 20:14, Naresh Kamboju <[email protected]> wrote:
>
> On Tue, 28 Jul 2020 at 22:04, Christoph Hellwig <[email protected]> wrote:
> >
> > Factor out a path_umount helper that takes a struct path * instead of the
> > actual file name. This will allow to convert the init and devtmpfs code
> > to properly mount based on a kernel pointer instead of relying on the
> > implicit set_fs(KERNEL_DS) during early init.
> >
> > Signed-off-by: Christoph Hellwig <[email protected]>
> > ---
> > fs/namespace.c | 40 ++++++++++++++++++----------------------
> > 1 file changed, 18 insertions(+), 22 deletions(-)
> >
> > diff --git a/fs/namespace.c b/fs/namespace.c
> > index 6f8234f74bed90..43834b59eff6c3 100644
> > --- a/fs/namespace.c
> > +++ b/fs/namespace.c
<trim>
>
> Regressions on linux next 20200803 tag kernel.
> LTP syscalls test umount03 mount a path for testing and
> umount failed and retired for 50 times and test exit with warning
> and following test cases using that mount path failed.
>
> LTP syscalls tests failed list,
> * umount03
> * umount2_01
> * umount2_02
> * umount2_03
> * utime06
> * copy_file_range01
The reported issue has been fixed in linux next 20200817 tag by
below patch.
fs: fix a struct path leak in path_umount
Make sure we also put the dentry and vfsmnt in the illegal flags and
!may_umount cases.
Fixes: 41525f56e256 ("fs: refactor ksys_umount")
- Naresh