git: 8bde6d15d1fa - main - nfsclient: Copy only initialized fields in nfs_getattr()

[Mark Johnston]

The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=8bde6d15d1fa9a947c2bdc5eddae36cfbb1076dc

commit 8bde6d15d1fa9a947c2bdc5eddae36cfbb1076dc
Author:     Mark Johnston <markj at FreeBSD.org>
AuthorDate: 2021-05-04 12:53:57 +0000
Commit:     Mark Johnston <markj at FreeBSD.org>
CommitDate: 2021-05-04 12:53:57 +0000

    nfsclient: Copy only initialized fields in nfs_getattr()
    
    When loading attributes from the cache, the NFS client is careful to
    copy only the fields that it initialized.  After fetching attributes
    from the server, however, it would copy the entire vattr structure
    initialized from the RPC response, so uninitialized stack bytes would
    end up being copied to userspace.  In particular, va_birthtime (v2 and
    v3) and va_gen (v3) had this problem.
    
    Use a common subroutine to copy fields provided by the NFS client, and
    ensure that we provide a dummy va_gen for the v3 case.
    
    Reviewed by:    rmacklem
    Reported by:    KMSAN
    MFC after:      1 week
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D30090
---
 sys/fs/nfs/nfsport.h             |  1 +
 sys/fs/nfsclient/nfs_clcomsubs.c |  1 +
 sys/fs/nfsclient/nfs_clport.c    | 24 +++++++++++++++++++++++-
 sys/fs/nfsclient/nfs_clvnops.c   | 19 ++-----------------
 4 files changed, 27 insertions(+), 18 deletions(-)

diff --git a/sys/fs/nfs/nfsport.h b/sys/fs/nfs/nfsport.h
index 6777dc72f6a3..cb82666ab397 100644
--- a/sys/fs/nfs/nfsport.h
+++ b/sys/fs/nfs/nfsport.h
@@ -1001,6 +1001,7 @@ int nfscl_loadattrcache(struct vnode **, struct nfsvattr *, void *, void *,
     int, int);
 int newnfs_realign(struct mbuf **, int);
 bool ncl_pager_setsize(struct vnode *vp, u_quad_t *nsizep);
+void ncl_copy_vattr(struct vattr *dst, struct vattr *src);
 
 /*
  * If the port runs on an SMP box that can enforce Atomic ops with low
diff --git a/sys/fs/nfsclient/nfs_clcomsubs.c b/sys/fs/nfsclient/nfs_clcomsubs.c
index 6a36aed478d9..8a51d51f093f 100644
--- a/sys/fs/nfsclient/nfs_clcomsubs.c
+++ b/sys/fs/nfsclient/nfs_clcomsubs.c
@@ -285,6 +285,7 @@ nfsm_loadattr(struct nfsrv_descript *nd, struct nfsvattr *nap)
 		fxdr_nfsv3time(&fp->fa3_ctime, &nap->na_ctime);
 		fxdr_nfsv3time(&fp->fa3_mtime, &nap->na_mtime);
 		nap->na_flags = 0;
+		nap->na_gen = 0;
 		nap->na_filerev = 0;
 	} else {
 		NFSM_DISSECT(fp, struct nfs_fattr *, NFSX_V2FATTR);
diff --git a/sys/fs/nfsclient/nfs_clport.c b/sys/fs/nfsclient/nfs_clport.c
index 81a0e05c3234..64820cd11f1c 100644
--- a/sys/fs/nfsclient/nfs_clport.c
+++ b/sys/fs/nfsclient/nfs_clport.c
@@ -400,6 +400,28 @@ nfscl_warn_fileid(struct nfsmount *nmp, struct nfsvattr *oldnap,
 		    ncl_fileid_maxwarnings);
 }
 
+void
+ncl_copy_vattr(struct vattr *dst, struct vattr *src)
+{
+	dst->va_type = src->va_type;
+	dst->va_mode = src->va_mode;
+	dst->va_nlink = src->va_nlink;
+	dst->va_uid = src->va_uid;
+	dst->va_gid = src->va_gid;
+	dst->va_fsid = src->va_fsid;
+	dst->va_fileid = src->va_fileid;
+	dst->va_size = src->va_size;
+	dst->va_blocksize = src->va_blocksize;
+	dst->va_atime = src->va_atime;
+	dst->va_mtime = src->va_mtime;
+	dst->va_ctime = src->va_ctime;
+	dst->va_gen = src->va_gen;
+	dst->va_flags = src->va_flags;
+	dst->va_rdev = src->va_rdev;
+	dst->va_bytes = src->va_bytes;
+	dst->va_filerev = src->va_filerev;
+}
+
 /*
  * Load the attribute cache (that lives in the nfsnode entry) with
  * the attributes of the second argument and
@@ -551,7 +573,7 @@ nfscl_loadattrcache(struct vnode **vpp, struct nfsvattr *nap, void *nvaper,
 		KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
 	}
 	if (vaper != NULL) {
-		NFSBCOPY((caddr_t)vap, (caddr_t)vaper, sizeof(*vap));
+		ncl_copy_vattr(vaper, vap);
 		if (np->n_flag & NCHG) {
 			if (np->n_flag & NACC)
 				vaper->va_atime = np->n_atim;
diff --git a/sys/fs/nfsclient/nfs_clvnops.c b/sys/fs/nfsclient/nfs_clvnops.c
index 217290b080b3..5f81bb5b42a4 100644
--- a/sys/fs/nfsclient/nfs_clvnops.c
+++ b/sys/fs/nfsclient/nfs_clvnops.c
@@ -962,23 +962,8 @@ nfs_getattr(struct vop_getattr_args *ap)
 	 * First look in the cache.
 	 */
 	if (ncl_getattrcache(vp, &vattr) == 0) {
-		vap->va_type = vattr.va_type;
-		vap->va_mode = vattr.va_mode;
-		vap->va_nlink = vattr.va_nlink;
-		vap->va_uid = vattr.va_uid;
-		vap->va_gid = vattr.va_gid;
-		vap->va_fsid = vattr.va_fsid;
-		vap->va_fileid = vattr.va_fileid;
-		vap->va_size = vattr.va_size;
-		vap->va_blocksize = vattr.va_blocksize;
-		vap->va_atime = vattr.va_atime;
-		vap->va_mtime = vattr.va_mtime;
-		vap->va_ctime = vattr.va_ctime;
-		vap->va_gen = vattr.va_gen;
-		vap->va_flags = vattr.va_flags;
-		vap->va_rdev = vattr.va_rdev;
-		vap->va_bytes = vattr.va_bytes;
-		vap->va_filerev = vattr.va_filerev;
+		ncl_copy_vattr(vap, &vattr);
+
 		/*
 		 * Get the local modify time for the case of a write
 		 * delegation.