FAILED: patch "[PATCH] nfsd: gate nfs2 setacl by argp->mask" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x a3a7e20ed66d3f04d37883c398da8a113b430769
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026090350-onyx-repaying-474c@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a3a7e20ed66d3f04d37883c398da8a113b430769 Mon Sep 17 00:00:00 2001
From: Chuck Lever <[email protected]>
Date: Sat, 30 May 2026 16:58:16 -0400
Subject: [PATCH] nfsd: gate nfs2 setacl by argp->mask

The NFSACL v2 SETACL path shares the decoder convention used by its v3 sibling: nfsaclsvc_decode_setaclargs() fills in argp->acl_access only when NFS_ACL is set in the request mask and argp->acl_default only when NFS_DFACL is set, leaving the other pointer NULL because the argument buffer is zeroed up to pc_argzero before decode.

nfsacld_proc_setacl() then hands both pointers to set_posix_acl() unconditionally. set_posix_acl(idmap, dentry, type, NULL) is the VFS "remove this ACL type" operation, so an omitted arm is indistinguishable from an explicit request to delete that ACL. A SETACL carrying only NFS_ACL silently strips the directory's default ACL; mask=0 strips both.

This is the same defect just fixed in nfsd3_proc_setacl(); apply the same remedy. Gate each set_posix_acl() call on its mask bit and initialize error to 0 so that a request with neither bit set leaves the on-disk ACLs untouched and returns success. The out_drop_lock path and the unconditional posix_acl_release() in nfsaclsvc_release_setacl() already tolerate the skipped arms.

index 76305b86c1a9..827f90194c43 100644
@@ -115,14 +115,19 @@ static __be32 nfsacld_proc_setacl(struct svc_rqst *rqstp)
 
 	inode_lock(inode);
 
-	error = set_posix_acl(&nop_mnt_idmap, fh->fh_dentry, ACL_TYPE_ACCESS,
-			      argp->acl_access);
-	if (error)
-		goto out_drop_lock;
-	error = set_posix_acl(&nop_mnt_idmap, fh->fh_dentry, ACL_TYPE_DEFAULT,
-			      argp->acl_default);
-	if (error)
-		goto out_drop_lock;
+	error = 0;
+	if (argp->mask & NFS_ACL) {
+		error = set_posix_acl(&nop_mnt_idmap, fh->fh_dentry,
+				      ACL_TYPE_ACCESS, argp->acl_access);
+		if (error)
+			goto out_drop_lock;
+	}
+	if (argp->mask & NFS_DFACL) {
+		error = set_posix_acl(&nop_mnt_idmap, fh->fh_dentry,
+				      ACL_TYPE_DEFAULT, argp->acl_default);
+		if (error)
+			goto out_drop_lock;
+	}
 
 	inode_unlock(inode);
 

From: Chuck Lever <[email protected]>

[ Upstream commit a3a7e20ed66d3f04d37883c398da8a113b430769 ]

The NFSACL v2 SETACL path shares the decoder convention used by its v3 sibling: nfsaclsvc_decode_setaclargs() fills in argp->acl_access only when NFS_ACL is set in the request mask and argp->acl_default only when NFS_DFACL is set, leaving the other pointer NULL because the argument buffer is zeroed up to pc_argzero before decode.

nfsacld_proc_setacl() then hands both pointers to set_posix_acl() unconditionally. set_posix_acl(idmap, dentry, type, NULL) is the VFS "remove this ACL type" operation, so an omitted arm is indistinguishable from an explicit request to delete that ACL. A SETACL carrying only NFS_ACL silently strips the directory's default ACL; mask=0 strips both.

This is the same defect just fixed in nfsd3_proc_setacl(); apply the same remedy. Gate each set_posix_acl() call on its mask bit and initialize error to 0 so that a request with neither bit set leaves the on-disk ACLs untouched and returns success. The out_drop_lock path and the unconditional posix_acl_release() in nfsaclsvc_release_setacl() already tolerate the skipped arms.

---
 fs/nfsd/nfs2acl.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

index 44b74d83560b5..6e2ed6947033c 100644
@@ -115,14 +115,19 @@ static __be32 nfsacld_proc_setacl(struct svc_rqst *rqstp)
 
 	inode_lock(inode);
 
-	error = set_posix_acl(&init_user_ns, inode, ACL_TYPE_ACCESS,
-			      argp->acl_access);
-	if (error)
-		goto out_drop_lock;
-	error = set_posix_acl(&init_user_ns, inode, ACL_TYPE_DEFAULT,
-			      argp->acl_default);
-	if (error)
-		goto out_drop_lock;
+	error = 0;
+	if (argp->mask & NFS_ACL) {
+		error = set_posix_acl(&init_user_ns, inode, ACL_TYPE_ACCESS,
+				      argp->acl_access);
+		if (error)
+			goto out_drop_lock;
+	}
+	if (argp->mask & NFS_DFACL) {
+		error = set_posix_acl(&init_user_ns, inode, ACL_TYPE_DEFAULT,
+				      argp->acl_default);
+		if (error)
+			goto out_drop_lock;
+	}
 
 	inode_unlock(inode);
 

2.53.0