nfs: add support for the umask attribute

Clients can set the umask attribute when creating files to cause the
server to apply it always except when inheriting permissions from the
parent directory.  That way, the new files will end up with the same
permissions as files created locally.

See https://tools.ietf.org/html/draft-ietf-nfsv4-umask-02 for more details.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 24 insertions, 12 deletions

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 1c1768a8fcd1..1af6268a7d8c 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -52,6 +52,7 @@
 #include <linux/nfs.h>
 #include <linux/nfs4.h>
 #include <linux/nfs_fs.h>
+#include <linux/fs_struct.h>
 
 #include "nfs4_fs.h"
 #include "internal.h"
@@ -1008,7 +1009,7 @@ static void encode_nfs4_verifier(struct xdr_stream *xdr, const nfs4_verifier *ve
 static void encode_attrs(struct xdr_stream *xdr, const struct iattr *iap,
                                 const struct nfs4_label *label,
                                 const struct nfs_server *server,
-                                bool excl_check)
+                                bool excl_check, const umode_t *umask)
 {
         char owner_name[IDMAP_NAMESZ];
         char owner_group[IDMAP_NAMESZ];
@@ -1022,18 +1023,21 @@ static void encode_attrs(struct xdr_stream *xdr, const struct iattr *iap,
 
         /*
          * We reserve enough space to write the entire attribute buffer at once.
-         * In the worst-case, this would be
-         * 16(bitmap) + 4(attrlen) + 8(size) + 4(mode) + 4(atime) + 4(mtime)
-         * = 40 bytes, plus any contribution from variable-length fields
-         *            such as owner/group.
          */
         if (iap->ia_valid & ATTR_SIZE) {
                 bmval[0] |= FATTR4_WORD0_SIZE;
                 len += 8;
         }
+        if (!(server->attr_bitmask[2] & FATTR4_WORD2_MODE_UMASK))
+                umask = NULL;
         if (iap->ia_valid & ATTR_MODE) {
-                bmval[1] |= FATTR4_WORD1_MODE;
-                len += 4;
+                if (umask) {
+                        bmval[2] |= FATTR4_WORD2_MODE_UMASK;
+                        len += 8;
+                } else {
+                        bmval[1] |= FATTR4_WORD1_MODE;
+                        len += 4;
+                }
         }
         if (iap->ia_valid & ATTR_UID) {
                 owner_namelen = nfs_map_uid_to_name(server, iap->ia_uid, owner_name, IDMAP_NAMESZ);
@@ -1134,6 +1138,10 @@ static void encode_attrs(struct xdr_stream *xdr, const struct iattr *iap,
                 *p++ = cpu_to_be32(label->len);
                 p = xdr_encode_opaque_fixed(p, label->label, label->len);
         }
+        if (bmval[2] & FATTR4_WORD2_MODE_UMASK) {
+                *p++ = cpu_to_be32(iap->ia_mode & S_IALLUGO);
+                *p++ = cpu_to_be32(*umask);
+        }
 
 /* out: */
 }
@@ -1188,7 +1196,8 @@ static void encode_create(struct xdr_stream *xdr, const struct nfs4_create_arg *
         }
 
         encode_string(xdr, create->name->len, create->name->name);
-        encode_attrs(xdr, create->attrs, create->label, create->server, false);
+        encode_attrs(xdr, create->attrs, create->label, create->server, false,
+                     &create->umask);
 }
 
 static void encode_getattr_one(struct xdr_stream *xdr, uint32_t bitmap, struct compound_hdr *hdr)
@@ -1408,11 +1417,13 @@ static inline void encode_createmode(struct xdr_stream *xdr, const struct nfs_op
         switch(arg->createmode) {
         case NFS4_CREATE_UNCHECKED:
                 *p = cpu_to_be32(NFS4_CREATE_UNCHECKED);
-                encode_attrs(xdr, arg->u.attrs, arg->label, arg->server, false);
+                encode_attrs(xdr, arg->u.attrs, arg->label, arg->server, false,
+                             &arg->umask);
                 break;
         case NFS4_CREATE_GUARDED:
                 *p = cpu_to_be32(NFS4_CREATE_GUARDED);
-                encode_attrs(xdr, arg->u.attrs, arg->label, arg->server, false);
+                encode_attrs(xdr, arg->u.attrs, arg->label, arg->server, false,
+                             &arg->umask);
                 break;
         case NFS4_CREATE_EXCLUSIVE:
                 *p = cpu_to_be32(NFS4_CREATE_EXCLUSIVE);
@@ -1421,7 +1432,8 @@ static inline void encode_createmode(struct xdr_stream *xdr, const struct nfs_op
         case NFS4_CREATE_EXCLUSIVE4_1:
                 *p = cpu_to_be32(NFS4_CREATE_EXCLUSIVE4_1);
                 encode_nfs4_verifier(xdr, &arg->u.verifier);
-                encode_attrs(xdr, arg->u.attrs, arg->label, arg->server, true);
+                encode_attrs(xdr, arg->u.attrs, arg->label, arg->server, true,
+                             &arg->umask);
         }
 }
 
@@ -1677,7 +1689,7 @@ static void encode_setattr(struct xdr_stream *xdr, const struct nfs_setattrargs
 {
         encode_op_hdr(xdr, OP_SETATTR, decode_setattr_maxsz, hdr);
         encode_nfs4_stateid(xdr, &arg->stateid);
-        encode_attrs(xdr, arg->iap, arg->label, server, false);
+        encode_attrs(xdr, arg->iap, arg->label, server, false, NULL);
 }
 
 static void encode_setclientid(struct xdr_stream *xdr, const struct nfs4_setclientid *setclientid, struct compound_hdr *hdr)