From: NeilBrown <neilb@suse.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org,
Amir Goldstein <amir73il@gmail.com>,
lkml <linux-kernel@vger.kernel.org>,
Lennart Poettering <lennart@poettering.net>
Subject: [PATCH 4/4] fhandle: Improve error responses in name_to_handle_at()
Date: Mon, 11 Dec 2017 17:04:05 +1100 [thread overview]
Message-ID: <151297224523.7818.12267549679803980398.stgit@noble> (raw)
In-Reply-To: <151297214390.7818.7216826079527521005.stgit@noble>
1/ Always return the mnt_id, even if some other error occurs.
It can be useful without the file handle.
An application can initialise the memory to, e.g. -1
and if there is some other value after name_to_handle_at()
returns, then it is a valid mnt_id.
If the value is unchanged, then the kernel does not
have this patch.
2/ Don't return -EINVAL if the requested handle_bytes is
larger than MAX_HANDLE_SZ. There is no need for an
error and it causes unnecessary behavior change
in the kernel ever needs to increase MAX_HANDLE_SZ.
Simple limit handle_bytes to MAX_HANDLE_SZ silently.
Signed-off-by: NeilBrown <neilb@suse.com>
---
fs/fhandle.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/fs/fhandle.c b/fs/fhandle.c
index 0ace128f5d23..04afffaeb742 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -23,9 +23,16 @@ static long do_sys_name_to_handle(struct path *path,
int handle_dwords, handle_bytes;
struct file_handle *handle = NULL;
+ /*
+ * Always return the mnt_id, it might be useful even
+ * without the file handle
+ */
+ if (copy_to_user(mnt_id, &real_mount(path->mnt)->mnt_id,
+ sizeof(*mnt_id)))
+ return -EFAULT;
/*
* We need to make sure whether the file system
- * support decoding of the file handle
+ * supports decoding of the file handle.
*/
if (!path->dentry->d_sb->s_export_op ||
!path->dentry->d_sb->s_export_op->fh_to_dentry)
@@ -35,7 +42,7 @@ static long do_sys_name_to_handle(struct path *path,
return -EFAULT;
if (f_handle.handle_bytes > MAX_HANDLE_SZ)
- return -EINVAL;
+ f_handle.handle_bytes = MAX_HANDLE_SZ;
handle = kmalloc(sizeof(struct file_handle) + f_handle.handle_bytes,
GFP_KERNEL);
@@ -68,10 +75,7 @@ static long do_sys_name_to_handle(struct path *path,
retval = -EOVERFLOW;
} else
retval = 0;
- /* copy the mount id */
- if (copy_to_user(mnt_id, &real_mount(path->mnt)->mnt_id,
- sizeof(*mnt_id)) ||
- copy_to_user(ufh, handle,
+ if (copy_to_user(ufh, handle,
sizeof(struct file_handle) + handle_bytes))
retval = -EFAULT;
kfree(handle);
next prev parent reply other threads:[~2017-12-11 6:04 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-11 6:04 [PATCH 0/4] VFS: fix assorted issues with name_to_handle conversions NeilBrown
2017-12-11 6:04 ` [PATCH 3/4] NFS: allow name_to_handle_at() to work for Amazon EFS NeilBrown
2017-12-11 6:04 ` [PATCH 2/4] fs/notify: don't put file handle buffer on stack NeilBrown
2017-12-11 6:47 ` Amir Goldstein
2017-12-11 6:04 ` [PATCH 1/4] fs/notify: fdinfo can report unsupported file handles NeilBrown
2017-12-11 6:29 ` Al Viro
2017-12-11 22:12 ` NeilBrown
2017-12-11 6:41 ` Amir Goldstein
2017-12-11 7:05 ` Amir Goldstein
2017-12-11 13:46 ` Pavel Emelyanov
2017-12-11 14:08 ` Amir Goldstein
2017-12-11 15:21 ` Pavel Emelyanov
2017-12-11 21:52 ` NeilBrown
2017-12-12 6:39 ` Amir Goldstein
2017-12-13 2:20 ` NeilBrown
2017-12-11 6:04 ` NeilBrown [this message]
2017-12-11 16:08 ` [PATCH 4/4] fhandle: Improve error responses in name_to_handle_at() J. Bruce Fields
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