* [PATCH] fscrypt: don't evict dirty inodes after removing key
@ 2020-03-05 8:41 ` Eric Biggers
0 siblings, 0 replies; 6+ messages in thread
From: Eric Biggers @ 2020-03-05 8:41 UTC (permalink / raw)
To: linux-fscrypt; +Cc: linux-fsdevel, linux-ext4, linux-mtd, linux-f2fs-devel
From: Eric Biggers <ebiggers@google.com>
After FS_IOC_REMOVE_ENCRYPTION_KEY removes a key, it syncs the
filesystem and tries to get and put all inodes that were unlocked by the
key so that unused inodes get evicted via fscrypt_drop_inode().
Normally, the inodes are all clean due to the sync.
However, after the filesystem is sync'ed, userspace can modify and close
one of the files. (Userspace is *supposed* to close the files before
removing the key. But it doesn't always happen, and the kernel can't
assume it.) This causes the inode to be dirtied and have i_count == 0.
Then, fscrypt_drop_inode() failed to consider this case and indicated
that the inode can be dropped, causing the write to be lost.
On f2fs, other problems such as a filesystem freeze could occur due to
the inode being freed while still on f2fs's dirty inode list.
Fix this bug by making fscrypt_drop_inode() only drop clean inodes.
I've written an xfstest which detects this bug on ext4, f2fs, and ubifs.
Fixes: b1c0ec3599f4 ("fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl")
Cc: <stable@vger.kernel.org> # v5.4+
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/crypto/keysetup.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index 65cb09fa6ead..08c9f216a54d 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -538,6 +538,15 @@ int fscrypt_drop_inode(struct inode *inode)
return 0;
mk = ci->ci_master_key->payload.data[0];
+ /*
+ * With proper, non-racy use of FS_IOC_REMOVE_ENCRYPTION_KEY, all inodes
+ * protected by the key were cleaned by sync_filesystem(). But if
+ * userspace is still using the files, inodes can be dirtied between
+ * then and now. We mustn't lose any writes, so skip dirty inodes here.
+ */
+ if (inode->i_state & I_DIRTY_ALL)
+ return 0;
+
/*
* Note: since we aren't holding ->mk_secret_sem, the result here can
* immediately become outdated. But there's no correctness problem with
--
2.25.1
______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/
^ permalink raw reply related [flat|nested] 6+ messages in thread* [f2fs-dev] [PATCH] fscrypt: don't evict dirty inodes after removing key
@ 2020-03-05 8:41 ` Eric Biggers
0 siblings, 0 replies; 6+ messages in thread
From: Eric Biggers @ 2020-03-05 8:41 UTC (permalink / raw)
To: linux-fscrypt; +Cc: linux-fsdevel, linux-ext4, linux-mtd, linux-f2fs-devel
From: Eric Biggers <ebiggers@google.com>
After FS_IOC_REMOVE_ENCRYPTION_KEY removes a key, it syncs the
filesystem and tries to get and put all inodes that were unlocked by the
key so that unused inodes get evicted via fscrypt_drop_inode().
Normally, the inodes are all clean due to the sync.
However, after the filesystem is sync'ed, userspace can modify and close
one of the files. (Userspace is *supposed* to close the files before
removing the key. But it doesn't always happen, and the kernel can't
assume it.) This causes the inode to be dirtied and have i_count == 0.
Then, fscrypt_drop_inode() failed to consider this case and indicated
that the inode can be dropped, causing the write to be lost.
On f2fs, other problems such as a filesystem freeze could occur due to
the inode being freed while still on f2fs's dirty inode list.
Fix this bug by making fscrypt_drop_inode() only drop clean inodes.
I've written an xfstest which detects this bug on ext4, f2fs, and ubifs.
Fixes: b1c0ec3599f4 ("fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl")
Cc: <stable@vger.kernel.org> # v5.4+
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/crypto/keysetup.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index 65cb09fa6ead..08c9f216a54d 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -538,6 +538,15 @@ int fscrypt_drop_inode(struct inode *inode)
return 0;
mk = ci->ci_master_key->payload.data[0];
+ /*
+ * With proper, non-racy use of FS_IOC_REMOVE_ENCRYPTION_KEY, all inodes
+ * protected by the key were cleaned by sync_filesystem(). But if
+ * userspace is still using the files, inodes can be dirtied between
+ * then and now. We mustn't lose any writes, so skip dirty inodes here.
+ */
+ if (inode->i_state & I_DIRTY_ALL)
+ return 0;
+
/*
* Note: since we aren't holding ->mk_secret_sem, the result here can
* immediately become outdated. But there's no correctness problem with
--
2.25.1
_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] fscrypt: don't evict dirty inodes after removing key
2020-03-05 8:41 ` [f2fs-dev] " Eric Biggers
(?)
@ 2020-03-11 2:50 ` Eric Biggers
-1 siblings, 0 replies; 6+ messages in thread
From: Eric Biggers @ 2020-03-11 2:50 UTC (permalink / raw)
To: linux-fscrypt; +Cc: linux-ext4, linux-f2fs-devel, linux-mtd, linux-fsdevel
On Thu, Mar 05, 2020 at 12:41:38AM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> After FS_IOC_REMOVE_ENCRYPTION_KEY removes a key, it syncs the
> filesystem and tries to get and put all inodes that were unlocked by the
> key so that unused inodes get evicted via fscrypt_drop_inode().
> Normally, the inodes are all clean due to the sync.
>
> However, after the filesystem is sync'ed, userspace can modify and close
> one of the files. (Userspace is *supposed* to close the files before
> removing the key. But it doesn't always happen, and the kernel can't
> assume it.) This causes the inode to be dirtied and have i_count == 0.
> Then, fscrypt_drop_inode() failed to consider this case and indicated
> that the inode can be dropped, causing the write to be lost.
>
> On f2fs, other problems such as a filesystem freeze could occur due to
> the inode being freed while still on f2fs's dirty inode list.
>
> Fix this bug by making fscrypt_drop_inode() only drop clean inodes.
>
> I've written an xfstest which detects this bug on ext4, f2fs, and ubifs.
>
> Fixes: b1c0ec3599f4 ("fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl")
> Cc: <stable@vger.kernel.org> # v5.4+
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> fs/crypto/keysetup.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
> index 65cb09fa6ead..08c9f216a54d 100644
> --- a/fs/crypto/keysetup.c
> +++ b/fs/crypto/keysetup.c
> @@ -538,6 +538,15 @@ int fscrypt_drop_inode(struct inode *inode)
> return 0;
> mk = ci->ci_master_key->payload.data[0];
>
> + /*
> + * With proper, non-racy use of FS_IOC_REMOVE_ENCRYPTION_KEY, all inodes
> + * protected by the key were cleaned by sync_filesystem(). But if
> + * userspace is still using the files, inodes can be dirtied between
> + * then and now. We mustn't lose any writes, so skip dirty inodes here.
> + */
> + if (inode->i_state & I_DIRTY_ALL)
> + return 0;
> +
> /*
> * Note: since we aren't holding ->mk_secret_sem, the result here can
> * immediately become outdated. But there's no correctness problem with
> --
Applied to fscrypt.git#for-stable for 5.6.
- Eric
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] fscrypt: don't evict dirty inodes after removing key
@ 2020-03-11 2:50 ` Eric Biggers
0 siblings, 0 replies; 6+ messages in thread
From: Eric Biggers @ 2020-03-11 2:50 UTC (permalink / raw)
To: linux-fscrypt; +Cc: linux-fsdevel, linux-ext4, linux-mtd, linux-f2fs-devel
On Thu, Mar 05, 2020 at 12:41:38AM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> After FS_IOC_REMOVE_ENCRYPTION_KEY removes a key, it syncs the
> filesystem and tries to get and put all inodes that were unlocked by the
> key so that unused inodes get evicted via fscrypt_drop_inode().
> Normally, the inodes are all clean due to the sync.
>
> However, after the filesystem is sync'ed, userspace can modify and close
> one of the files. (Userspace is *supposed* to close the files before
> removing the key. But it doesn't always happen, and the kernel can't
> assume it.) This causes the inode to be dirtied and have i_count == 0.
> Then, fscrypt_drop_inode() failed to consider this case and indicated
> that the inode can be dropped, causing the write to be lost.
>
> On f2fs, other problems such as a filesystem freeze could occur due to
> the inode being freed while still on f2fs's dirty inode list.
>
> Fix this bug by making fscrypt_drop_inode() only drop clean inodes.
>
> I've written an xfstest which detects this bug on ext4, f2fs, and ubifs.
>
> Fixes: b1c0ec3599f4 ("fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl")
> Cc: <stable@vger.kernel.org> # v5.4+
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> fs/crypto/keysetup.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
> index 65cb09fa6ead..08c9f216a54d 100644
> --- a/fs/crypto/keysetup.c
> +++ b/fs/crypto/keysetup.c
> @@ -538,6 +538,15 @@ int fscrypt_drop_inode(struct inode *inode)
> return 0;
> mk = ci->ci_master_key->payload.data[0];
>
> + /*
> + * With proper, non-racy use of FS_IOC_REMOVE_ENCRYPTION_KEY, all inodes
> + * protected by the key were cleaned by sync_filesystem(). But if
> + * userspace is still using the files, inodes can be dirtied between
> + * then and now. We mustn't lose any writes, so skip dirty inodes here.
> + */
> + if (inode->i_state & I_DIRTY_ALL)
> + return 0;
> +
> /*
> * Note: since we aren't holding ->mk_secret_sem, the result here can
> * immediately become outdated. But there's no correctness problem with
> --
Applied to fscrypt.git#for-stable for 5.6.
- Eric
______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [f2fs-dev] [PATCH] fscrypt: don't evict dirty inodes after removing key
@ 2020-03-11 2:50 ` Eric Biggers
0 siblings, 0 replies; 6+ messages in thread
From: Eric Biggers @ 2020-03-11 2:50 UTC (permalink / raw)
To: linux-fscrypt; +Cc: linux-fsdevel, linux-ext4, linux-mtd, linux-f2fs-devel
On Thu, Mar 05, 2020 at 12:41:38AM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> After FS_IOC_REMOVE_ENCRYPTION_KEY removes a key, it syncs the
> filesystem and tries to get and put all inodes that were unlocked by the
> key so that unused inodes get evicted via fscrypt_drop_inode().
> Normally, the inodes are all clean due to the sync.
>
> However, after the filesystem is sync'ed, userspace can modify and close
> one of the files. (Userspace is *supposed* to close the files before
> removing the key. But it doesn't always happen, and the kernel can't
> assume it.) This causes the inode to be dirtied and have i_count == 0.
> Then, fscrypt_drop_inode() failed to consider this case and indicated
> that the inode can be dropped, causing the write to be lost.
>
> On f2fs, other problems such as a filesystem freeze could occur due to
> the inode being freed while still on f2fs's dirty inode list.
>
> Fix this bug by making fscrypt_drop_inode() only drop clean inodes.
>
> I've written an xfstest which detects this bug on ext4, f2fs, and ubifs.
>
> Fixes: b1c0ec3599f4 ("fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl")
> Cc: <stable@vger.kernel.org> # v5.4+
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> fs/crypto/keysetup.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
> index 65cb09fa6ead..08c9f216a54d 100644
> --- a/fs/crypto/keysetup.c
> +++ b/fs/crypto/keysetup.c
> @@ -538,6 +538,15 @@ int fscrypt_drop_inode(struct inode *inode)
> return 0;
> mk = ci->ci_master_key->payload.data[0];
>
> + /*
> + * With proper, non-racy use of FS_IOC_REMOVE_ENCRYPTION_KEY, all inodes
> + * protected by the key were cleaned by sync_filesystem(). But if
> + * userspace is still using the files, inodes can be dirtied between
> + * then and now. We mustn't lose any writes, so skip dirty inodes here.
> + */
> + if (inode->i_state & I_DIRTY_ALL)
> + return 0;
> +
> /*
> * Note: since we aren't holding ->mk_secret_sem, the result here can
> * immediately become outdated. But there's no correctness problem with
> --
Applied to fscrypt.git#for-stable for 5.6.
- Eric
_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
^ permalink raw reply [flat|nested] 6+ messages in thread