From: NeilBrown <neilb@xxxxxxx>
nfsd_file_acquire_local() can be used to look up a file by filehandle
without having a struct svc_rqst. This can be used by NFS LOCALIO to
allow the NFS client to bypass the NFS protocol to directly access a
file provided by the NFS server which is running in the same kernel.
In nfsd_file_do_acquire() care is taken to always use fh_verify() if
rqstp is not NULL (as is the case for non-LOCALIO callers). Otherwise
the non-LOCALIO callers will not supply the correct and required
arguments to __fh_verify (e.g. gssclient isn't passed).
Introduce fh_verify_local() wrapper around __fh_verify to make it
clear that LOCALIO is intended caller.
Also, use GC for nfsd_file returned by nfsd_file_acquire_local. GC
offers performance improvements if/when a file is reopened before
launderette cleans it from the filecache's LRU.
Suggested-by: Jeff Layton <jlayton@xxxxxxxxxx> # use filecache's GC
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Co-developed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/nfsd/filecache.c | 71 ++++++++++++++++++++++++++++++++++++++++-----
fs/nfsd/filecache.h | 3 ++
fs/nfsd/nfsfh.c | 23 +++++++++++++++
fs/nfsd/nfsfh.h | 2 ++
4 files changed, 92 insertions(+), 7 deletions(-)
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 9e9d246f993c..2dc72de31f61 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -982,12 +982,14 @@ nfsd_file_is_cached(struct inode *inode)
}
static __be32
-nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
+nfsd_file_do_acquire(struct svc_rqst *rqstp, struct net *net,
+ struct svc_cred *cred,
+ struct auth_domain *client,
+ struct svc_fh *fhp,
unsigned int may_flags, struct file *file,
struct nfsd_file **pnf, bool want_gc)
{
unsigned char need = may_flags & NFSD_FILE_MAY_MASK;
- struct net *net = SVC_NET(rqstp);
struct nfsd_file *new, *nf;
bool stale_retry = true;
bool open_retry = true;
@@ -996,8 +998,13 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
int ret;
retry:
- status = fh_verify(rqstp, fhp, S_IFREG,
- may_flags|NFSD_MAY_OWNER_OVERRIDE);
+ if (rqstp) {
+ status = fh_verify(rqstp, fhp, S_IFREG,
+ may_flags|NFSD_MAY_OWNER_OVERRIDE);
+ } else {
+ status = fh_verify_local(net, cred, client, fhp, S_IFREG,
+ may_flags|NFSD_MAY_OWNER_OVERRIDE);
+ }
if (status != nfs_ok)
return status;
inode = d_inode(fhp->fh_dentry);
@@ -1143,7 +1150,8 @@ __be32
nfsd_file_acquire_gc(struct svc_rqst *rqstp, struct svc_fh *fhp,
unsigned int may_flags, struct nfsd_file **pnf)
{
- return nfsd_file_do_acquire(rqstp, fhp, may_flags, NULL, pnf, true);
+ return nfsd_file_do_acquire(rqstp, SVC_NET(rqstp), NULL, NULL,
+ fhp, may_flags, NULL, pnf, true);
}
/**
@@ -1167,7 +1175,55 @@ __be32
nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
unsigned int may_flags, struct nfsd_file **pnf)
{
- return nfsd_file_do_acquire(rqstp, fhp, may_flags, NULL, pnf, false);
+ return nfsd_file_do_acquire(rqstp, SVC_NET(rqstp), NULL, NULL,
+ fhp, may_flags, NULL, pnf, false);
+}
+
+/**
+ * nfsd_file_acquire_local - Get a struct nfsd_file with an open file for localio
+ * @net: The network namespace in which to perform a lookup
+ * @cred: the user credential with which to validate access
+ * @client: the auth_domain for LOCALIO lookup
+ * @fhp: the NFS filehandle of the file to be opened
+ * @may_flags: NFSD_MAY_ settings for the file
+ * @pnf: OUT: new or found "struct nfsd_file" object
+ *
+ * This file lookup interface provide access to a file given the
+ * filehandle and credential. No connection-based authorisation
+ * is performed and in that way it is quite different to other
+ * file access mediated by nfsd. It allows a kernel module such as the NFS
+ * client to reach across network and filesystem namespaces to access
+ * a file. The security implications of this should be carefully
+ * considered before use.
+ *
+ * The nfsd_file object returned by this API is reference-counted
+ * and garbage-collected. The object is retained for a few
+ * seconds after the final nfsd_file_put() in case the caller
+ * wants to re-use it.
+ *
+ * Return values:
+ * %nfs_ok - @pnf points to an nfsd_file with its reference
+ * count boosted.
+ *
+ * On error, an nfsstat value in network byte order is returned.
+ */
+__be32
+nfsd_file_acquire_local(struct net *net, struct svc_cred *cred,
+ struct auth_domain *client, struct svc_fh *fhp,
+ unsigned int may_flags, struct nfsd_file **pnf)
+{
+ /*
+ * Save creds before calling nfsd_file_do_acquire() (which calls
+ * nfsd_setuser). Important because caller (LOCALIO) is from
+ * client context.
+ */
+ const struct cred *save_cred = get_current_cred();
+ __be32 beres;
+
+ beres = nfsd_file_do_acquire(NULL, net, cred, client,
+ fhp, may_flags, NULL, pnf, true);
+ revert_creds(save_cred);
+ return beres;
}
/**
@@ -1193,7 +1249,8 @@ nfsd_file_acquire_opened(struct svc_rqst *rqstp, struct svc_fh *fhp,
unsigned int may_flags, struct file *file,
struct nfsd_file **pnf)
{
- return nfsd_file_do_acquire(rqstp, fhp, may_flags, file, pnf, false);
+ return nfsd_file_do_acquire(rqstp, SVC_NET(rqstp), NULL, NULL,
+ fhp, may_flags, file, pnf, false);
}
/*
diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h
index 3fbec24eea6c..26ada78b8c1e 100644
--- a/fs/nfsd/filecache.h
+++ b/fs/nfsd/filecache.h
@@ -66,5 +66,8 @@ __be32 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
__be32 nfsd_file_acquire_opened(struct svc_rqst *rqstp, struct svc_fh *fhp,
unsigned int may_flags, struct file *file,
struct nfsd_file **nfp);
+__be32 nfsd_file_acquire_local(struct net *net, struct svc_cred *cred,
+ struct auth_domain *client, struct svc_fh *fhp,
+ unsigned int may_flags, struct nfsd_file **pnf);
int nfsd_file_cache_stats_show(struct seq_file *m, void *v);
#endif /* _FS_NFSD_FILECACHE_H */
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index a77af71892a3..40ad58a6a036 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -392,6 +392,29 @@ __fh_verify(struct svc_rqst *rqstp,
return error;
}
+/**
+ * fh_verify_local - filehandle lookup and access checking
+ * @net: net namespace in which to perform the export lookup
+ * @cred: RPC user credential
+ * @client: RPC auth domain
+ * @fhp: filehandle to be verified
+ * @type: expected type of object pointed to by filehandle
+ * @access: type of access needed to object
+ *
+ * This API can be used by callers who do not have an RPC
+ * transaction context (ie are not running in an nfsd thread).
+ *
+ * See fh_verify() for further descriptions of @fhp, @type, and @access.
+ */
+__be32
+fh_verify_local(struct net *net, struct svc_cred *cred,
+ struct auth_domain *client, struct svc_fh *fhp,
+ umode_t type, int access)
+{
+ return __fh_verify(NULL, net, cred, client, NULL,
+ fhp, type, access);
+}
+
/**
* fh_verify - filehandle lookup and access checking
* @rqstp: pointer to current rpc request
diff --git a/fs/nfsd/nfsfh.h b/fs/nfsd/nfsfh.h
index 8d46e203d139..5b7394801dc4 100644
--- a/fs/nfsd/nfsfh.h
+++ b/fs/nfsd/nfsfh.h
@@ -217,6 +217,8 @@ extern char * SVCFH_fmt(struct svc_fh *fhp);
* Function prototypes
*/
__be32 fh_verify(struct svc_rqst *, struct svc_fh *, umode_t, int);
+__be32 fh_verify_local(struct net *, struct svc_cred *, struct auth_domain *,
+ struct svc_fh *, umode_t, int);
__be32 fh_compose(struct svc_fh *, struct svc_export *, struct dentry *, struct svc_fh *);
__be32 fh_update(struct svc_fh *);
void fh_put(struct svc_fh *);
--
2.44.0
