[PATCH 5.16 155/285] NFSv4: fix open failure with O_ACCMODE flag

Greg Kroah-Hartman
2022-04-12T07:56:40Z

From: ChenXiaoSong <chenxiaosong2@huawei.com>

[ Upstream commit b243874f6f9568b2daf1a00e9222cacdc15e159c ]

open() with O_ACCMODE|O_DIRECT flags secondly will fail.

Reproducer:
1. mount -t nfs -o vers=4.2 $server_ip:/ /mnt/
2. fd = open("/mnt/file", O_ACCMODE|O_DIRECT|O_CREAT)
3. close(fd)
4. fd = open("/mnt/file", O_ACCMODE|O_DIRECT)

Server nfsd4_decode_share_access() will fail with error nfserr_bad_xdr when
client use incorrect share access mode of 0.

Fix this by using NFS4_SHARE_ACCESS_BOTH share access mode in client,
just like firstly opening.

Fixes: ce4ef7c0a8a05 ("NFS: Split out NFS v4 file operations")
Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/nfs/dir.c | 10 ----------
fs/nfs/internal.h | 10 ++++++++++
fs/nfs/nfs4file.c | 6 ++++--
3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 877f72433f43..503b9eef4533 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1830,16 +1830,6 @@ const struct dentry_operations nfs4_dentry_operations = {
};
EXPORT_SYMBOL_GPL(nfs4_dentry_operations);

-static fmode_t flags_to_mode(int flags)
-{
- fmode_t res = (__force fmode_t)flags & FMODE_EXEC;
- if ((flags & O_ACCMODE) != O_WRONLY)
- res |= FMODE_READ;
- if ((flags & O_ACCMODE) != O_RDONLY)
- res |= FMODE_WRITE;
- return res;
-}
-
static struct nfs_open_context *create_nfs_open_context(struct dentry *dentry, int open_flags, struct file *filp)
{
return alloc_nfs_open_context(dentry, flags_to_mode(open_flags), filp);
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 85957db80975..dd62f0525e80 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -42,6 +42,16 @@ static inline bool nfs_lookup_is_soft_revalidate(const struct dentry *dentry)
return true;
}

+static inline fmode_t flags_to_mode(int flags)
+{
+ fmode_t res = (__force fmode_t)flags & FMODE_EXEC;
+ if ((flags & O_ACCMODE) != O_WRONLY)
+ res |= FMODE_READ;
+ if ((flags & O_ACCMODE) != O_RDONLY)
+ res |= FMODE_WRITE;
+ return res;
+}
+
/*
* Note: RFC 1813 doesn't limit the number of auth flavors that
* a server can return, so make something up.
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index c178db86a6e8..e34af48fb4f4 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -32,6 +32,7 @@ nfs4_file_open(struct inode *inode, struct file *filp)
struct dentry *parent = NULL;
struct inode *dir;
unsigned openflags = filp->f_flags;
+ fmode_t f_mode;
struct iattr attr;
int err;

@@ -50,8 +51,9 @@ nfs4_file_open(struct inode *inode, struct file *filp)
if (err)
return err;

+ f_mode = filp->f_mode;
if ((openflags & O_ACCMODE) == 3)
- openflags--;
+ f_mode |= flags_to_mode(openflags);

/* We can't create new files here */
openflags &= ~(O_CREAT|O_EXCL);
@@ -59,7 +61,7 @@ nfs4_file_open(struct inode *inode, struct file *filp)
parent = dget_parent(dentry);
dir = d_inode(parent);

- ctx = alloc_nfs_open_context(file_dentry(filp), filp->f_mode, filp);
+ ctx = alloc_nfs_open_context(file_dentry(filp), f_mode, filp);
err = PTR_ERR(ctx);
if (IS_ERR(ctx))
goto out;
--
2.35.1