| Message ID | 1454373300-2751-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index c442a74..acb851d 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -2285,6 +2285,9 @@ int nfs_permission(struct inode *inode, int mask) case S_IFLNK: goto out; case S_IFREG: + if ((mask & MAY_OPEN) && + nfs_server_capable(inode, NFS_CAP_ATOMIC_OPEN)) + return 0; break; case S_IFDIR: /*
This is a note to let you know that I have just added a patch titled NFSv4: Don't perform cached access checks before we've OPENed the file to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt34. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From e282bd6b1361abfe4cfe2b72e2d2adca37c5a82c Mon Sep 17 00:00:00 2001 From: Trond Myklebust <trond.myklebust@primarydata.com> Date: Sat, 26 Dec 2015 21:54:58 -0500 Subject: NFSv4: Don't perform cached access checks before we've OPENed the file commit 762674f86d0328d5dc923c966e209e1ee59663f2 upstream. Donald Buczek reports that a nfs4 client incorrectly denies execute access based on outdated file mode (missing 'x' bit). After the mode on the server is 'fixed' (chmod +x) further execution attempts continue to fail, because the nfs ACCESS call updates the access parameter but not the mode parameter or the mode in the inode. The root cause is ultimately that the VFS is calling may_open() before the NFS client has a chance to OPEN the file and hence revalidate the access and attribute caches. Al Viro suggests: >>> Make nfs_permission() relax the checks when it sees MAY_OPEN, if you know >>> that things will be caught by server anyway? >> >> That can work as long as we're guaranteed that everything that calls >> inode_permission() with MAY_OPEN on a regular file will also follow up >> with a vfs_open() or dentry_open() on success. Is this always the >> case? > > 1) in do_tmpfile(), followed by do_dentry_open() (not reachable by NFS since > it doesn't have ->tmpfile() instance anyway) > > 2) in atomic_open(), after the call of ->atomic_open() has succeeded. > > 3) in do_last(), followed on success by vfs_open() > > That's all. All calls of inode_permission() that get MAY_OPEN come from > may_open(), and there's no other callers of that puppy. Reported-by: Donald Buczek <buczek@molgen.mpg.de> Link: https://bugzilla.kernel.org/show_bug.cgi?id=109771 Link: http://lkml.kernel.org/r/1451046656-26319-1-git-send-email-buczek@molgen.mpg.de Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- fs/nfs/dir.c | 3 +++ 1 file changed, 3 insertions(+) -- 1.9.1