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Subject: [PATCH 05/13] NFSD: add security label to struct nfsd_attrs
From:   NeilBrown <neilb@suse.de>
To:     Chuck Lever III <chuck.lever@oracle.com>,
        Jeff Layton <jlayton@kernel.org>
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Date:   Tue, 26 Jul 2022 16:45:30 +1000
Message-ID: <165881793056.21666.14726745370568724977.stgit@noble.brown>
In-Reply-To: <165881740958.21666.5904057696047278505.stgit@noble.brown>
References: <165881740958.21666.5904057696047278505.stgit@noble.brown>
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nfsd_setattr() now sets a security label if provided, and nfsv4 provides
it in the 'open' and 'create' paths and the 'setattr' path.
If setting the label failed (including because the kernel doesn't
support labels), an error field in 'struct nfsd_attrs' is set, and the
caller can respond.  The open/create callers clear
FATTR4_WORD2_SECURITY_LABEL in the returned attr set in this case.
The setattr caller returns the error.

Signed-off-by: NeilBrown <neilb@suse.de>
---
 fs/nfsd/nfs4proc.c |   61 +++++++++++++++-------------------------------------
 fs/nfsd/vfs.c      |   29 +++----------------------
 fs/nfsd/vfs.h      |    4 ++-
 3 files changed, 23 insertions(+), 71 deletions(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index ee72c94732f0..83d2b645b0d6 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -64,36 +64,6 @@ MODULE_PARM_DESC(nfsd4_ssc_umount_timeout,
 		"idle msecs before unmount export from source server");
 #endif
 
-#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
-#include <linux/security.h>
-
-static inline void
-nfsd4_security_inode_setsecctx(struct svc_fh *resfh, struct xdr_netobj *label, u32 *bmval)
-{
-	struct inode *inode = d_inode(resfh->fh_dentry);
-	int status;
-
-	inode_lock(inode);
-	status = security_inode_setsecctx(resfh->fh_dentry,
-		label->data, label->len);
-	inode_unlock(inode);
-
-	if (status)
-		/*
-		 * XXX: We should really fail the whole open, but we may
-		 * already have created a new file, so it may be too
-		 * late.  For now this seems the least of evils:
-		 */
-		bmval[2] &= ~FATTR4_WORD2_SECURITY_LABEL;
-
-	return;
-}
-#else
-static inline void
-nfsd4_security_inode_setsecctx(struct svc_fh *resfh, struct xdr_netobj *label, u32 *bmval)
-{ }
-#endif
-
 #define NFSDDBG_FACILITY		NFSDDBG_PROC
 
 static u32 nfsd_attrmask[] = {
@@ -286,7 +256,10 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		  struct svc_fh *resfhp, struct nfsd4_open *open)
 {
 	struct iattr *iap = &open->op_iattr;
-	struct nfsd_attrs attrs = { .iattr = iap };
+	struct nfsd_attrs attrs = {
+		.iattr = iap,
+		.label = &open->op_label,
+	};
 	struct dentry *parent, *child;
 	__u32 v_mtime, v_atime;
 	struct inode *inode;
@@ -407,6 +380,8 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
 set_attr:
 	status = nfsd_create_setattr(rqstp, fhp, resfhp, &attrs);
 
+	if (attrs.label_failed)
+		open->op_bmval[2] &= ~FATTR4_WORD2_SECURITY_LABEL;
 out:
 	fh_unlock(fhp);
 	if (child && !IS_ERR(child))
@@ -448,9 +423,6 @@ do_open_lookup(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, stru
 		status = nfsd4_create_file(rqstp, current_fh, *resfh, open);
 		current->fs->umask = 0;
 
-		if (!status && open->op_label.len)
-			nfsd4_security_inode_setsecctx(*resfh, &open->op_label, open->op_bmval);
-
 		/*
 		 * Following rfc 3530 14.2.16, and rfc 5661 18.16.4
 		 * use the returned bitmask to indicate which attributes
@@ -788,7 +760,10 @@ nfsd4_create(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	     union nfsd4_op_u *u)
 {
 	struct nfsd4_create *create = &u->create;
-	struct nfsd_attrs attrs = { .iattr = &create->cr_iattr };
+	struct nfsd_attrs attrs = {
+		.iattr = &create->cr_iattr,
+		.label = &create->cr_label,
+	};
 	struct svc_fh resfh;
 	__be32 status;
 	dev_t rdev;
@@ -860,8 +835,8 @@ nfsd4_create(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	if (status)
 		goto out;
 
-	if (create->cr_label.len)
-		nfsd4_security_inode_setsecctx(&resfh, &create->cr_label, create->cr_bmval);
+	if (attrs.label_failed)
+		create->cr_bmval[2] &= ~FATTR4_WORD2_SECURITY_LABEL;
 
 	if (create->cr_acl != NULL)
 		do_set_nfs4_acl(rqstp, &resfh, create->cr_acl,
@@ -1144,7 +1119,10 @@ nfsd4_setattr(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	      union nfsd4_op_u *u)
 {
 	struct nfsd4_setattr *setattr = &u->setattr;
-	struct nfsd_attrs attrs = { .iattr = &setattr->sa_iattr };
+	struct nfsd_attrs attrs = {
+		.iattr = &setattr->sa_iattr,
+		.label = &setattr->sa_label,
+	};
 	__be32 status = nfs_ok;
 	int err;
 
@@ -1172,13 +1150,10 @@ nfsd4_setattr(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 					    setattr->sa_acl);
 	if (status)
 		goto out;
-	if (setattr->sa_label.len)
-		status = nfsd4_set_nfs4_label(rqstp, &cstate->current_fh,
-				&setattr->sa_label);
-	if (status)
-		goto out;
 	status = nfsd_setattr(rqstp, &cstate->current_fh, &attrs,
 				0, (time64_t)0);
+	if (!status)
+		status = attrs.label_failed;
 out:
 	fh_drop_write(&cstate->current_fh);
 	return status;
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 91c9ea09f921..e7a18bedf499 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -458,6 +458,9 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	host_err = notify_change(&init_user_ns, dentry, iap, NULL);
 
 out_unlock:
+	if (attr->label && attr->label->len)
+		attr->label_failed = security_inode_setsecctx(
+			dentry, attr->label->data, attr->label->len);
 	fh_unlock(fhp);
 	if (size_change)
 		put_write_access(inode);
@@ -496,32 +499,6 @@ int nfsd4_is_junction(struct dentry *dentry)
 		return 0;
 	return 1;
 }
-#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
-__be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
-		struct xdr_netobj *label)
-{
-	__be32 error;
-	int host_error;
-	struct dentry *dentry;
-
-	error = fh_verify(rqstp, fhp, 0 /* S_IFREG */, NFSD_MAY_SATTR);
-	if (error)
-		return error;
-
-	dentry = fhp->fh_dentry;
-
-	inode_lock(d_inode(dentry));
-	host_error = security_inode_setsecctx(dentry, label->data, label->len);
-	inode_unlock(d_inode(dentry));
-	return nfserrno(host_error);
-}
-#else
-__be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
-		struct xdr_netobj *label)
-{
-	return nfserr_notsupp;
-}
-#endif
 
 static struct nfsd4_compound_state *nfsd4_get_cstate(struct svc_rqst *rqstp)
 {
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index f3f43ca3ac6b..8464e04af1ea 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -44,6 +44,8 @@ typedef int (*nfsd_filldir_t)(void *, const char *, int, loff_t, u64, unsigned);
 /* nfsd/vfs.c */
 struct nfsd_attrs {
 	struct iattr *iattr;
+	struct xdr_netobj *label;
+	int label_failed;
 };
 
 int		nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
@@ -57,8 +59,6 @@ __be32		nfsd_setattr(struct svc_rqst *, struct svc_fh *,
 				struct nfsd_attrs *, int, time64_t);
 int nfsd_mountpoint(struct dentry *, struct svc_export *);
 #ifdef CONFIG_NFSD_V4
-__be32          nfsd4_set_nfs4_label(struct svc_rqst *, struct svc_fh *,
-		    struct xdr_netobj *);
 __be32		nfsd4_vfs_fallocate(struct svc_rqst *, struct svc_fh *,
 				    struct file *, loff_t, loff_t, int);
 __be32		nfsd4_clone_file_range(struct svc_rqst *rqstp,