2016-09-28 18:34:48

by Eric Biggers

Subject: [PATCH] fscrypto: lock inode while setting encryption policy

i_rwsem needs to be acquired while setting an encryption policy so that
concurrent calls to FS_IOC_SET_ENCRYPTION_POLICY are correctly
serialized (especially the ->get_context() + ->set_context() pair), and
so that new files cannot be created in the directory during or after the
->empty_dir() check.

Signed-off-by: Eric Biggers <[email protected]>

---
Note: to be applied without conflict, this patch needs the changes from
v4.8-rc6.

---
fs/crypto/policy.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index ed115ac..6865663 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -109,6 +109,8 @@ int fscrypt_process_policy(struct file *filp,
if (ret)
return ret;

+ inode_lock(inode);
+
if (!inode_has_encryption_context(inode)) {
if (!S_ISDIR(inode->i_mode))
ret = -EINVAL;
@@ -127,6 +129,8 @@ int fscrypt_process_policy(struct file *filp,
ret = -EINVAL;
}

+ inode_unlock(inode);
+
mnt_drop_write_file(filp);
return ret;
}
--
2.8.0.rc3.226.g39d4020

2016-09-29 17:20:25

by Richard Weinberger

Subject: Re: [PATCH] fscrypto: lock inode while setting encryption policy

On 28.09.2016 20:34, Eric Biggers wrote:
> i_rwsem needs to be acquired while setting an encryption policy so that
> concurrent calls to FS_IOC_SET_ENCRYPTION_POLICY are correctly
> serialized (especially the ->get_context() + ->set_context() pair), and
> so that new files cannot be created in the directory during or after the
> ->empty_dir() check.
>
> Signed-off-by: Eric Biggers <[email protected]>

Reviewed-by: Richard Weinberger <[email protected]>

Thanks,
//richard

2016-10-14 18:11:52

by Eric Biggers

Subject: Re: [PATCH] fscrypto: lock inode while setting encryption policy

On Thu, Sep 29, 2016 at 07:20:20PM +0200, Richard Weinberger wrote:
> On 28.09.2016 20:34, Eric Biggers wrote:
> > i_rwsem needs to be acquired while setting an encryption policy so that
> > concurrent calls to FS_IOC_SET_ENCRYPTION_POLICY are correctly
> > serialized (especially the ->get_context() + ->set_context() pair), and
> > so that new files cannot be created in the directory during or after the
> > ->empty_dir() check.
> >
> > Signed-off-by: Eric Biggers <[email protected]>
>
> Reviewed-by: Richard Weinberger <[email protected]>
>
> Thanks,
> //richard

Thanks. Does anyone else have comments on this patch? It hasn't been applied
yet.

Eric

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2016-10-15 13:54:01

by Theodore Ts'o

Subject: Re: [PATCH] fscrypto: lock inode while setting encryption policy

On Thu, Sep 29, 2016 at 07:20:20PM +0200, Richard Weinberger wrote:
> On 28.09.2016 20:34, Eric Biggers wrote:
> > i_rwsem needs to be acquired while setting an encryption policy so that
> > concurrent calls to FS_IOC_SET_ENCRYPTION_POLICY are correctly
> > serialized (especially the ->get_context() + ->set_context() pair), and
> > so that new files cannot be created in the directory during or after the
> > ->empty_dir() check.
> >
> > Signed-off-by: Eric Biggers <[email protected]>
>
> Reviewed-by: Richard Weinberger <[email protected]>

Thanks, applied.

- Ted