Author: rmacklem
Date: Fri Nov 23 00:17:47 2018
New Revision: 340787
URL: https://svnweb.freebsd.org/changeset/base/340787

Log:
  Make sure the NFS readdir client fills in all "struct dirent" data.
  
  The NFS client code (nfsrpc_readdir() and nfsrpc_readdirplus()) wasn't
  filling in parts of the readdir reply, such as d_pad[01] and the bytes
  at the end of d_name within d_reclen. As such, data left in a buffer cache
  block could be leaked to userland in the readdir reply.
  This patch makes sure all of the data is filled in.
  
  Reported by:  Thomas Barabosch, Fraunhofer FKIE
  Reviewed by:  kib, markj
  MFC after:    2 weeks

Modified:
  head/sys/fs/nfsclient/nfs_clrpcops.c

Modified: head/sys/fs/nfsclient/nfs_clrpcops.c
==============================================================================
--- head/sys/fs/nfsclient/nfs_clrpcops.c        Thu Nov 22 21:38:24 2018        
(r340786)
+++ head/sys/fs/nfsclient/nfs_clrpcops.c        Fri Nov 23 00:17:47 2018        
(r340787)
@@ -2959,6 +2959,7 @@ nfsrpc_readdir(vnode_t vp, struct uio *uiop, nfsuint64
                            return (error);
                        nd->nd_mrep = NULL;
                        dp = (struct dirent *)uio_iov_base(uiop);
+                       dp->d_pad0 = dp->d_pad1 = 0;
                        dp->d_off = 0;
                        dp->d_type = DT_DIR;
                        dp->d_fileno = dotfileid;
@@ -2978,6 +2979,7 @@ nfsrpc_readdir(vnode_t vp, struct uio *uiop, nfsuint64
                        uio_iov_base_add(uiop, dp->d_reclen);
                        uio_iov_len_add(uiop, -(dp->d_reclen));
                        dp = (struct dirent *)uio_iov_base(uiop);
+                       dp->d_pad0 = dp->d_pad1 = 0;
                        dp->d_off = 0;
                        dp->d_type = DT_DIR;
                        dp->d_fileno = dotdotfileid;
@@ -3091,6 +3093,7 @@ nfsrpc_readdir(vnode_t vp, struct uio *uiop, nfsuint64
                                tlen += 8;  /* To ensure null termination. */
                        left = DIRBLKSIZ - blksiz;
                        if (_GENERIC_DIRLEN(len) + NFSX_HYPER > left) {
+                               NFSBZERO(uio_iov_base(uiop), left);
                                dp->d_reclen += left;
                                uio_iov_base_add(uiop, left);
                                uio_iov_len_add(uiop, -(left));
@@ -3103,6 +3106,7 @@ nfsrpc_readdir(vnode_t vp, struct uio *uiop, nfsuint64
                                bigenough = 0;
                        if (bigenough) {
                                dp = (struct dirent *)uio_iov_base(uiop);
+                               dp->d_pad0 = dp->d_pad1 = 0;
                                dp->d_off = 0;
                                dp->d_namlen = len;
                                dp->d_reclen = _GENERIC_DIRLEN(len) +
@@ -3120,7 +3124,7 @@ nfsrpc_readdir(vnode_t vp, struct uio *uiop, nfsuint64
                                        goto nfsmout;
                                cp = uio_iov_base(uiop);
                                tlen -= len;
-                               *cp = '\0';     /* null terminate */
+                               NFSBZERO(cp, tlen);
                                cp += tlen;     /* points to cookie storage */
                                tl2 = (u_int32_t *)cp;
                                uio_iov_base_add(uiop, (tlen + NFSX_HYPER));
@@ -3208,6 +3212,7 @@ nfsrpc_readdir(vnode_t vp, struct uio *uiop, nfsuint64
         */
        if (blksiz > 0) {
                left = DIRBLKSIZ - blksiz;
+               NFSBZERO(uio_iov_base(uiop), left);
                dp->d_reclen += left;
                uio_iov_base_add(uiop, left);
                uio_iov_len_add(uiop, -(left));
@@ -3235,10 +3240,8 @@ nfsrpc_readdir(vnode_t vp, struct uio *uiop, nfsuint64
         */
        while (uio_uio_resid(uiop) > 0 && uio_uio_resid(uiop) != tresid) {
                dp = (struct dirent *)uio_iov_base(uiop);
+               NFSBZERO(dp, DIRBLKSIZ);
                dp->d_type = DT_UNKNOWN;
-               dp->d_fileno = 0;
-               dp->d_namlen = 0;
-               dp->d_name[0] = '\0';
                tl = (u_int32_t *)&dp->d_name[4];
                *tl++ = cookie.lval[0];
                *tl = cookie.lval[1];
@@ -3393,6 +3396,7 @@ nfsrpc_readdirplus(vnode_t vp, struct uio *uiop, nfsui
                            return (error);
                        nd->nd_mrep = NULL;
                        dp = (struct dirent *)uio_iov_base(uiop);
+                       dp->d_pad0 = dp->d_pad1 = 0;
                        dp->d_off = 0;
                        dp->d_type = DT_DIR;
                        dp->d_fileno = dotfileid;
@@ -3412,6 +3416,7 @@ nfsrpc_readdirplus(vnode_t vp, struct uio *uiop, nfsui
                        uio_iov_base_add(uiop, dp->d_reclen);
                        uio_iov_len_add(uiop, -(dp->d_reclen));
                        dp = (struct dirent *)uio_iov_base(uiop);
+                       dp->d_pad0 = dp->d_pad1 = 0;
                        dp->d_off = 0;
                        dp->d_type = DT_DIR;
                        dp->d_fileno = dotdotfileid;
@@ -3506,6 +3511,7 @@ nfsrpc_readdirplus(vnode_t vp, struct uio *uiop, nfsui
                                tlen += 8;  /* To ensure null termination. */
                        left = DIRBLKSIZ - blksiz;
                        if (_GENERIC_DIRLEN(len) + NFSX_HYPER > left) {
+                               NFSBZERO(uio_iov_base(uiop), left);
                                dp->d_reclen += left;
                                uio_iov_base_add(uiop, left);
                                uio_iov_len_add(uiop, -(left));
@@ -3518,6 +3524,7 @@ nfsrpc_readdirplus(vnode_t vp, struct uio *uiop, nfsui
                                bigenough = 0;
                        if (bigenough) {
                                dp = (struct dirent *)uio_iov_base(uiop);
+                               dp->d_pad0 = dp->d_pad1 = 0;
                                dp->d_off = 0;
                                dp->d_namlen = len;
                                dp->d_reclen = _GENERIC_DIRLEN(len) +
@@ -3538,7 +3545,7 @@ nfsrpc_readdirplus(vnode_t vp, struct uio *uiop, nfsui
                                        goto nfsmout;
                                cp = uio_iov_base(uiop);
                                tlen -= len;
-                               *cp = '\0';
+                               NFSBZERO(cp, tlen);
                                cp += tlen;     /* points to cookie storage */
                                tl2 = (u_int32_t *)cp;
                                if (len == 2 && cnp->cn_nameptr[0] == '.' &&
@@ -3708,6 +3715,7 @@ nfsrpc_readdirplus(vnode_t vp, struct uio *uiop, nfsui
         */
        if (blksiz > 0) {
                left = DIRBLKSIZ - blksiz;
+               NFSBZERO(uio_iov_base(uiop), left);
                dp->d_reclen += left;
                uio_iov_base_add(uiop, left);
                uio_iov_len_add(uiop, -(left));
@@ -3735,10 +3743,8 @@ nfsrpc_readdirplus(vnode_t vp, struct uio *uiop, nfsui
         */
        while (uio_uio_resid(uiop) > 0 && uio_uio_resid(uiop) != tresid) {
                dp = (struct dirent *)uio_iov_base(uiop);
+               NFSBZERO(dp, DIRBLKSIZ);
                dp->d_type = DT_UNKNOWN;
-               dp->d_fileno = 0;
-               dp->d_namlen = 0;
-               dp->d_name[0] = '\0';
                tl = (u_int32_t *)&dp->d_name[4];
                *tl++ = cookie.lval[0];
                *tl = cookie.lval[1];
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