NFSv4.2 mode_umask support

NFSv4.2 mode_umask support

[J. Bruce Fields]

Since the last version, just two minor changes:

	- client uses the stored supported attribute results instead of
	  a new capability flag.
	- if a nutty client attempts to set both mode and new attribute,
	  the server returns INVAL instead of ignoring the mode.

Description, as before:

The following patches allow the umask to be ignored in the presence of
inheritable NFSv4 ACLs.  Otherwise inheritable ACLs can be rendered
mostly useless whenever the umask masks out group bits.

This solves a problem we've seen complaints about for some time, both
upstream and from RHEL users.

The new protocol has been discussed in the IETF working group and is
documented at:

	https://tools.ietf.org/html/draft-ietf-nfsv4-umask-02

It's unlikely that we'll discover problems requiring an incompatible
change, so I think we should consider this for 4.10.

--b.

[PATCH 1/2] nfs: add support for the umask attribute

[J. Bruce Fields]

From: Andreas Gruenbacher <agruenba@redhat.com>

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>
---
 fs/nfs/dir.c            |  7 ++++++-
 fs/nfs/nfs4proc.c       | 16 ++++++++++++----
 fs/nfs/nfs4xdr.c        | 36 ++++++++++++++++++++++++------------
 include/linux/nfs4.h    |  1 +
 include/linux/nfs_xdr.h |  2 ++
 5 files changed, 45 insertions(+), 17 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 5f1af4cd1a33..837f12e683df 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1535,8 +1535,13 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
 		return -ENAMETOOLONG;
 
 	if (open_flags & O_CREAT) {
+		struct nfs_server *server = NFS_SERVER(dir);
+
+		if (!(server->attr_bitmask[2] & FATTR4_WORD2_MODE_UMASK))
+			mode &= ~current_umask();
+
 		attr.ia_valid |= ATTR_MODE;
-		attr.ia_mode = mode & ~current_umask();
+		attr.ia_mode = mode;
 	}
 	if (open_flags & O_TRUNC) {
 		attr.ia_valid |= ATTR_SIZE;
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 7897826d7c51..df739778e4b3 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1239,6 +1239,7 @@ static struct nfs4_opendata *nfs4_opendata_alloc(struct dentry *dentry,
 	p->o_arg.bitmask = nfs4_bitmask(server, label);
 	p->o_arg.open_bitmap = &nfs4_fattr_bitmap[0];
 	p->o_arg.label = nfs4_label_copy(p->a_label, label);
+	p->o_arg.umask = current_umask();
 	p->o_arg.claim = nfs4_map_atomic_open_claim(server, claim);
 	switch (p->o_arg.claim) {
 	case NFS4_OPEN_CLAIM_NULL:
@@ -3277,7 +3278,7 @@ static void nfs4_close_context(struct nfs_open_context *ctx, int is_sync)
 
 #define FATTR4_WORD1_NFS40_MASK (2*FATTR4_WORD1_MOUNTED_ON_FILEID - 1UL)
 #define FATTR4_WORD2_NFS41_MASK (2*FATTR4_WORD2_SUPPATTR_EXCLCREAT - 1UL)
-#define FATTR4_WORD2_NFS42_MASK (2*FATTR4_WORD2_SECURITY_LABEL - 1UL)
+#define FATTR4_WORD2_NFS42_MASK (2*FATTR4_WORD2_MODE_UMASK - 1UL)
 
 static int _nfs4_server_capabilities(struct nfs_server *server, struct nfs_fh *fhandle)
 {
@@ -3953,6 +3954,7 @@ static int
 nfs4_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
 		 int flags)
 {
+	struct nfs_server *server = NFS_SERVER(dir);
 	struct nfs4_label l, *ilabel = NULL;
 	struct nfs_open_context *ctx;
 	struct nfs4_state *state;
@@ -3964,7 +3966,8 @@ nfs4_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
 
 	ilabel = nfs4_label_init_security(dir, dentry, sattr, &l);
 
-	sattr->ia_mode &= ~current_umask();
+	if (!(server->attr_bitmask[2] & FATTR4_WORD2_MODE_UMASK))
+		sattr->ia_mode &= ~current_umask();
 	state = nfs4_do_open(dir, ctx, flags, sattr, ilabel, NULL);
 	if (IS_ERR(state)) {
 		status = PTR_ERR(state);
@@ -4172,6 +4175,7 @@ static struct nfs4_createdata *nfs4_alloc_createdata(struct inode *dir,
 		data->arg.attrs = sattr;
 		data->arg.ftype = ftype;
 		data->arg.bitmask = nfs4_bitmask(server, data->label);
+		data->arg.umask = current_umask();
 		data->res.server = server;
 		data->res.fh = &data->fh;
 		data->res.fattr = &data->fattr;
@@ -4269,13 +4273,15 @@ static int _nfs4_proc_mkdir(struct inode *dir, struct dentry *dentry,
 static int nfs4_proc_mkdir(struct inode *dir, struct dentry *dentry,
 		struct iattr *sattr)
 {
+	struct nfs_server *server = NFS_SERVER(dir);
 	struct nfs4_exception exception = { };
 	struct nfs4_label l, *label = NULL;
 	int err;
 
 	label = nfs4_label_init_security(dir, dentry, sattr, &l);
 
-	sattr->ia_mode &= ~current_umask();
+	if (!(server->attr_bitmask[2] & FATTR4_WORD2_MODE_UMASK))
+		sattr->ia_mode &= ~current_umask();
 	do {
 		err = _nfs4_proc_mkdir(dir, dentry, sattr, label);
 		trace_nfs4_mkdir(dir, &dentry->d_name, err);
@@ -4378,13 +4384,15 @@ static int _nfs4_proc_mknod(struct inode *dir, struct dentry *dentry,
 static int nfs4_proc_mknod(struct inode *dir, struct dentry *dentry,
 		struct iattr *sattr, dev_t rdev)
 {
+	struct nfs_server *server = NFS_SERVER(dir);
 	struct nfs4_exception exception = { };
 	struct nfs4_label l, *label = NULL;
 	int err;
 
 	label = nfs4_label_init_security(dir, dentry, sattr, &l);
 
-	sattr->ia_mode &= ~current_umask();
+	if (!(server->attr_bitmask[2] & FATTR4_WORD2_MODE_UMASK))
+		sattr->ia_mode &= ~current_umask();
 	do {
 		err = _nfs4_proc_mknod(dir, dentry, sattr, label, rdev);
 		trace_nfs4_mknod(dir, &dentry->d_name, err);
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index fc89e5ed07ee..b94706f0668b 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"
@@ -1003,7 +1004,7 @@ 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];
@@ -1017,18 +1018,21 @@ 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);
@@ -1129,6 +1133,10 @@ 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: */
 }
@@ -1183,7 +1191,8 @@ 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)
@@ -1403,11 +1412,13 @@ 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);
@@ -1416,7 +1427,8 @@ 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);
 	}
 }
 
@@ -1672,7 +1684,7 @@ 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)
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index 9094faf0699d..bca536341d1a 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -440,6 +440,7 @@ enum lock_type4 {
 #define FATTR4_WORD2_MDSTHRESHOLD       (1UL << 4)
 #define FATTR4_WORD2_CLONE_BLKSIZE	(1UL << 13)
 #define FATTR4_WORD2_SECURITY_LABEL     (1UL << 16)
+#define FATTR4_WORD2_MODE_UMASK		(1UL << 17)
 
 /* MDS threshold bitmap bits */
 #define THRESHOLD_RD                    (1UL << 0)
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index beb1e10f446e..ff82f42da656 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -418,6 +418,7 @@ struct nfs_openargs {
 	enum open_claim_type4	claim;
 	enum createmode4	createmode;
 	const struct nfs4_label *label;
+	umode_t			umask;
 };
 
 struct nfs_openres {
@@ -937,6 +938,7 @@ struct nfs4_create_arg {
 	const struct nfs_fh *		dir_fh;
 	const u32 *			bitmask;
 	const struct nfs4_label		*label;
+	umode_t				umask;
 };
 
 struct nfs4_create_res {
-- 
2.9.3

[PATCH 2/2] nfsd: add support for the umask attribute

[J. Bruce Fields]

From: Andreas Gruenbacher <agruenba@redhat.com>

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>
---
 fs/nfsd/nfs4proc.c |  3 +++
 fs/nfsd/nfs4xdr.c  | 26 +++++++++++++++++++++-----
 fs/nfsd/nfsd.h     |  9 +++++++--
 fs/nfsd/nfssvc.c   |  4 ++--
 4 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index e901cf124e9f..74a6e573e061 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -102,6 +102,9 @@ check_attr_support(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		return nfserr_attrnotsupp;
 	if (writable && !bmval_is_subset(bmval, writable))
 		return nfserr_inval;
+	if (writable && (bmval[2] & FATTR4_WORD2_MODE_UMASK) &&
+			(bmval[1] & FATTR4_WORD1_MODE))
+		return nfserr_inval;
 	return nfs_ok;
 }
 
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 281739e1d477..79edde4577b2 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -33,6 +33,7 @@
  *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <linux/fs_struct.h>
 #include <linux/file.h>
 #include <linux/slab.h>
 #include <linux/namei.h>
@@ -299,7 +300,7 @@ nfsd4_decode_bitmap(struct nfsd4_compoundargs *argp, u32 *bmval)
 static __be32
 nfsd4_decode_fattr(struct nfsd4_compoundargs *argp, u32 *bmval,
 		   struct iattr *iattr, struct nfs4_acl **acl,
-		   struct xdr_netobj *label)
+		   struct xdr_netobj *label, int *umask)
 {
 	int expected_len, len = 0;
 	u32 dummy32;
@@ -457,6 +458,17 @@ nfsd4_decode_fattr(struct nfsd4_compoundargs *argp, u32 *bmval,
 			return nfserr_jukebox;
 	}
 #endif
+	if (bmval[2] & FATTR4_WORD2_MODE_UMASK) {
+		if (!umask)
+			goto xdr_error;
+		READ_BUF(8);
+		len += 8;
+		dummy32 = be32_to_cpup(p++);
+		iattr->ia_mode = dummy32 & (S_IFMT | S_IALLUGO);
+		dummy32 = be32_to_cpup(p++);
+		*umask = dummy32 & S_IRWXUGO;
+		iattr->ia_valid |= ATTR_MODE;
+	}
 	if (len != expected_len)
 		goto xdr_error;
 
@@ -651,7 +663,8 @@ nfsd4_decode_create(struct nfsd4_compoundargs *argp, struct nfsd4_create *create
 		return status;
 
 	status = nfsd4_decode_fattr(argp, create->cr_bmval, &create->cr_iattr,
-				    &create->cr_acl, &create->cr_label);
+				    &create->cr_acl, &create->cr_label,
+				    &current->fs->umask);
 	if (status)
 		goto out;
 
@@ -896,13 +909,15 @@ nfsd4_decode_open(struct nfsd4_compoundargs *argp, struct nfsd4_open *open)
 	case NFS4_OPEN_NOCREATE:
 		break;
 	case NFS4_OPEN_CREATE:
+		current->fs->umask = 0;
 		READ_BUF(4);
 		open->op_createmode = be32_to_cpup(p++);
 		switch (open->op_createmode) {
 		case NFS4_CREATE_UNCHECKED:
 		case NFS4_CREATE_GUARDED:
 			status = nfsd4_decode_fattr(argp, open->op_bmval,
-				&open->op_iattr, &open->op_acl, &open->op_label);
+				&open->op_iattr, &open->op_acl, &open->op_label,
+				&current->fs->umask);
 			if (status)
 				goto out;
 			break;
@@ -916,7 +931,8 @@ nfsd4_decode_open(struct nfsd4_compoundargs *argp, struct nfsd4_open *open)
 			READ_BUF(NFS4_VERIFIER_SIZE);
 			COPYMEM(open->op_verf.data, NFS4_VERIFIER_SIZE);
 			status = nfsd4_decode_fattr(argp, open->op_bmval,
-				&open->op_iattr, &open->op_acl, &open->op_label);
+				&open->op_iattr, &open->op_acl, &open->op_label,
+				&current->fs->umask);
 			if (status)
 				goto out;
 			break;
@@ -1153,7 +1169,7 @@ nfsd4_decode_setattr(struct nfsd4_compoundargs *argp, struct nfsd4_setattr *seta
 	if (status)
 		return status;
 	return nfsd4_decode_fattr(argp, setattr->sa_bmval, &setattr->sa_iattr,
-				  &setattr->sa_acl, &setattr->sa_label);
+				  &setattr->sa_acl, &setattr->sa_label, NULL);
 }
 
 static __be32
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 7155239b2908..d74c8c44dc35 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -359,6 +359,7 @@ void		nfsd_lockd_shutdown(void);
 
 #define NFSD4_2_SUPPORTED_ATTRS_WORD2 \
 	(NFSD4_1_SUPPORTED_ATTRS_WORD2 | \
+	FATTR4_WORD2_MODE_UMASK | \
 	NFSD4_2_SECURITY_ATTRS)
 
 extern u32 nfsd_suppattrs[3][3];
@@ -390,10 +391,14 @@ static inline bool nfsd_attrs_supported(u32 minorversion, u32 *bmval)
 	(FATTR4_WORD1_MODE | FATTR4_WORD1_OWNER | FATTR4_WORD1_OWNER_GROUP \
 	| FATTR4_WORD1_TIME_ACCESS_SET | FATTR4_WORD1_TIME_MODIFY_SET)
 #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
-#define NFSD_WRITEABLE_ATTRS_WORD2 FATTR4_WORD2_SECURITY_LABEL
+#define MAYBE_FATTR4_WORD2_SECURITY_LABEL \
+	FATTR4_WORD2_SECURITY_LABEL
 #else
-#define NFSD_WRITEABLE_ATTRS_WORD2 0
+#define MAYBE_FATTR4_WORD2_SECURITY_LABEL 0
 #endif
+#define NFSD_WRITEABLE_ATTRS_WORD2 \
+	(FATTR4_WORD2_MODE_UMASK \
+	| MAYBE_FATTR4_WORD2_SECURITY_LABEL)
 
 #define NFSD_SUPPATTR_EXCLCREAT_WORD0 \
 	NFSD_WRITEABLE_ATTRS_WORD0
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index a2b65fc56dd6..e6bfd96734c0 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -661,8 +661,8 @@ nfsd(void *vrqstp)
 	mutex_lock(&nfsd_mutex);
 
 	/* At this point, the thread shares current->fs
-	 * with the init process. We need to create files with a
-	 * umask of 0 instead of init's umask. */
+	 * with the init process. We need to create files with the
+	 * umask as defined by the client instead of init's umask. */
 	if (unshare_fs_struct() < 0) {
 		printk("Unable to start nfsd thread: out of memory\n");
 		goto out;
-- 
2.9.3

Re: NFSv4.2 mode_umask support

[J. Bruce Fields]

Ping--is there anything holding these up?

--b.

On Fri, Dec 02, 2016 at 10:53:02PM -0500, J. Bruce Fields wrote:
> Since the last version, just two minor changes:
> 
> 	- client uses the stored supported attribute results instead of
> 	  a new capability flag.
> 	- if a nutty client attempts to set both mode and new attribute,
> 	  the server returns INVAL instead of ignoring the mode.
> 
> Description, as before:
> 
> The following patches allow the umask to be ignored in the presence of
> inheritable NFSv4 ACLs.  Otherwise inheritable ACLs can be rendered
> mostly useless whenever the umask masks out group bits.
> 
> This solves a problem we've seen complaints about for some time, both
> upstream and from RHEL users.
> 
> The new protocol has been discussed in the IETF working group and is
> documented at:
> 
> 	https://tools.ietf.org/html/draft-ietf-nfsv4-umask-02
> 
> It's unlikely that we'll discover problems requiring an incompatible
> change, so I think we should consider this for 4.10.
> 
> --b.

NFSv4.2 mode_umask support

[J. Bruce Fields]

Resending--can we get any opinions on these?

The following patches allow the umask to be ignored in the presence of
inheritable NFSv4 ACLs.  Otherwise inheritable ACLs can be rendered
mostly useless whenever the umask masks out group bits.

This solves a problem we've seen complaints about for some time, both
upstream and from RHEL users.

The new protocol has been discussed in the IETF working group and is
documented at:

        https://tools.ietf.org/html/draft-ietf-nfsv4-umask-02

It's unlikely that we'll discover problems requiring an incompatible
change, so I think we should consider this for 4.10.

--b.