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Message-id: <172462816214.6062.16988455872478253419@noble.neil.brown.name>
Date: Mon, 26 Aug 2024 09:22:42 +1000
From: "NeilBrown" <neilb@...e.de>
To: "Chuck Lever" <chuck.lever@...cle.com>
Cc: "Jeff Layton" <jlayton@...nel.org>, "Olga Kornievskaia" <kolga@...app.com>,
"Dai Ngo" <dai.ngo@...cle.com>, "Tom Talpey" <tom@...pey.com>,
"linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/2] nfsd: CB_GETATTR fixes
On Sun, 25 Aug 2024, Chuck Lever wrote:
> On Fri, Aug 23, 2024 at 06:27:37PM -0400, Jeff Layton wrote:
> > Fixes for a couple of CB_GETATTR bugs I found while working on the
> > delstid set. Mostly this just ensures that we hold references to the
> > delegation while working with it.
> >
> >
>
> Applied to nfsd-fixes for v6.11-rc, thanks!
>
> [1/2] nfsd: hold reference to delegation when updating it for cb_getattr
> commit: 8fceb5f6636bbbf803fe29fff59f138206559964
> [2/2] nfsd: fix potential UAF in nfsd4_cb_getattr_release
> commit: 8bc97f9b84c8852fcc56be2382f5115c518de785
>
> --
> Chuck Lever
>
Maybe the following can tidy up that code. I can split this into
a few separate patches if you like.
Thoughts?
Note that the patch is easier to review if you apply it then use "git
diff -b".
NeilBrown
From: NeilBrown <neilb@...e.de>
Subject: [PATCH] nfsd: untangle code in nfsd4_deleg_getattr_conflict()
The code in nfsd4_deleg_getattr_conflict() is convoluted and buggy.
With this patch we:
- properly handle non-nfsd leases. We must not assume flc_owner is a
delegation unless fl_lmops == &nfsd_lease_mng_ops
- move the main code out of the for loop
- have a single exit which calls nfs4_put_stid()
(and other exits which don't need to call that)
Fixes: c5967721e106 ("NFSD: handle GETATTR conflict with write delegation")
Signed-off-by: NeilBrown <neilb@...e.de>
---
fs/nfsd/nfs4state.c | 130 ++++++++++++++++++++++----------------------
1 file changed, 65 insertions(+), 65 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 2c4b9a22b2bb..7672fa7a70f3 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -8837,6 +8837,7 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
struct inode *inode = d_inode(dentry);
struct file_lock_context *ctx;
+ struct nfs4_delegation *dp = NULL;
struct nfs4_cb_fattr *ncf;
struct file_lease *fl;
struct iattr attrs;
@@ -8845,77 +8846,76 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
ctx = locks_inode_context(inode);
if (!ctx)
return 0;
+
+#define NON_NFSD_LEASE ((void*)1)
+
spin_lock(&ctx->flc_lock);
for_each_file_lock(fl, &ctx->flc_lease) {
- unsigned char type = fl->c.flc_type;
-
if (fl->c.flc_flags == FL_LAYOUT)
continue;
- if (fl->fl_lmops != &nfsd_lease_mng_ops) {
- /*
- * non-nfs lease, if it's a lease with F_RDLCK then
- * we are done; there isn't any write delegation
- * on this inode
- */
- if (type == F_RDLCK)
- break;
- goto break_lease;
- }
- if (type == F_WRLCK) {
- struct nfs4_delegation *dp = fl->c.flc_owner;
-
- if (dp->dl_recall.cb_clp == *(rqstp->rq_lease_breaker)) {
- spin_unlock(&ctx->flc_lock);
- return 0;
- }
-break_lease:
- nfsd_stats_wdeleg_getattr_inc(nn);
- dp = fl->c.flc_owner;
- refcount_inc(&dp->dl_stid.sc_count);
- ncf = &dp->dl_cb_fattr;
- nfs4_cb_getattr(&dp->dl_cb_fattr);
- spin_unlock(&ctx->flc_lock);
- wait_on_bit_timeout(&ncf->ncf_cb_flags, CB_GETATTR_BUSY,
- TASK_INTERRUPTIBLE, NFSD_CB_GETATTR_TIMEOUT);
- if (ncf->ncf_cb_status) {
- /* Recall delegation only if client didn't respond */
- status = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
- if (status != nfserr_jukebox ||
- !nfsd_wait_for_delegreturn(rqstp, inode)) {
- nfs4_put_stid(&dp->dl_stid);
- return status;
- }
- }
- if (!ncf->ncf_file_modified &&
- (ncf->ncf_initial_cinfo != ncf->ncf_cb_change ||
- ncf->ncf_cur_fsize != ncf->ncf_cb_fsize))
- ncf->ncf_file_modified = true;
- if (ncf->ncf_file_modified) {
- int err;
-
- /*
- * Per section 10.4.3 of RFC 8881, the server would
- * not update the file's metadata with the client's
- * modified size
- */
- attrs.ia_mtime = attrs.ia_ctime = current_time(inode);
- attrs.ia_valid = ATTR_MTIME | ATTR_CTIME | ATTR_DELEG;
- inode_lock(inode);
- err = notify_change(&nop_mnt_idmap, dentry, &attrs, NULL);
- inode_unlock(inode);
- if (err) {
- nfs4_put_stid(&dp->dl_stid);
- return nfserrno(err);
- }
- ncf->ncf_cur_fsize = ncf->ncf_cb_fsize;
- *size = ncf->ncf_cur_fsize;
- *modified = true;
- }
- nfs4_put_stid(&dp->dl_stid);
- return 0;
+ if (fl->c.flc_type == F_WRLCK) {
+ if (fl->fl_lmops == &nfsd_lease_mng_ops)
+ dp = fl->c.flc_owner;
+ else
+ dp = NON_NFSD_LEASE;
}
break;
}
+ if (dp == NULL || dp == NON_NFSD_LEASE ||
+ dp->dl_recall.cb_clp == *(rqstp->rq_lease_breaker)) {
+ spin_unlock(&ctx->flc_lock);
+ if (dp == NON_NFSD_LEASE) {
+ status = nfserrno(nfsd_open_break_lease(inode,
+ NFSD_MAY_READ));
+ if (status != nfserr_jukebox ||
+ !nfsd_wait_for_delegreturn(rqstp, inode))
+ return status;
+ }
+ return 0;
+ }
+
+ nfsd_stats_wdeleg_getattr_inc(nn);
+ refcount_inc(&dp->dl_stid.sc_count);
+ ncf = &dp->dl_cb_fattr;
+ nfs4_cb_getattr(&dp->dl_cb_fattr);
spin_unlock(&ctx->flc_lock);
- return 0;
+
+ wait_on_bit_timeout(&ncf->ncf_cb_flags, CB_GETATTR_BUSY,
+ TASK_INTERRUPTIBLE, NFSD_CB_GETATTR_TIMEOUT);
+ if (ncf->ncf_cb_status) {
+ /* Recall delegation only if client didn't respond */
+ status = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
+ if (status != nfserr_jukebox ||
+ !nfsd_wait_for_delegreturn(rqstp, inode))
+ goto out_status;
+ }
+ if (!ncf->ncf_file_modified &&
+ (ncf->ncf_initial_cinfo != ncf->ncf_cb_change ||
+ ncf->ncf_cur_fsize != ncf->ncf_cb_fsize))
+ ncf->ncf_file_modified = true;
+ if (ncf->ncf_file_modified) {
+ int err;
+
+ /*
+ * Per section 10.4.3 of RFC 8881, the server would
+ * not update the file's metadata with the client's
+ * modified size
+ */
+ attrs.ia_mtime = attrs.ia_ctime = current_time(inode);
+ attrs.ia_valid = ATTR_MTIME | ATTR_CTIME | ATTR_DELEG;
+ inode_lock(inode);
+ err = notify_change(&nop_mnt_idmap, dentry, &attrs, NULL);
+ inode_unlock(inode);
+ if (err) {
+ status = nfserrno(err);
+ goto out_status;
+ }
+ ncf->ncf_cur_fsize = ncf->ncf_cb_fsize;
+ *size = ncf->ncf_cur_fsize;
+ *modified = true;
+ }
+ status = 0;
+out_status:
+ nfs4_put_stid(&dp->dl_stid);
+ return status;
}
--
2.44.0
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