[PATCH] NFSD: Fix nfs4_verifier memory alignment

[Chuck Lever <chuck.lever@oracle.com>]

Clean up due to code review.

The nfs4_verifier's data field is not guaranteed to be u32-aligned.
Casting an array of chars to a u32 * is considered generally
hazardous.

We can fix most of this by using a __be32 array to generate the
verifier's contents and then byte-copying it into the verifier field.

However, there is one spot where there is a backwards compatibility
constraint: the do_nfsd_create() call expects a verifier which is
32-bit aligned.  Fix this spot by forcing the alignment of the create
verifier in the nfsd4_open args structure.

Also, sizeof(nfs4_verifer) is the size of the in-core verifier data
structure, but NFS4_VERIFIER_SIZE is the number of octets in an XDR'd
verifier.  The two are not interchangeable, even if they happen to
have the same value.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---

Hi Bruce-

Compile-tested only.  Does this look reasonable?


 fs/nfsd/nfs4proc.c  |   19 +++++++++++--------
 fs/nfsd/nfs4state.c |    8 ++++----
 fs/nfsd/nfs4xdr.c   |   28 ++++++++++++++--------------
 fs/nfsd/xdr4.h      |    4 ++--
 4 files changed, 31 insertions(+), 28 deletions(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 896da74..e4b5748 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -481,14 +481,20 @@ nfsd4_access(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 			   &access->ac_supported);
 }
 
+static void gen_boot_verifier(nfs4_verifier *verifier)
+{
+	__be32 verf[2];
+
+	verf[0] = (__be32)nfssvc_boot.tv_sec;
+	verf[1] = (__be32)nfssvc_boot.tv_usec;
+	memcpy(verifier->data, verf, sizeof(verifier->data));
+}
+
 static __be32
 nfsd4_commit(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	     struct nfsd4_commit *commit)
 {
-	u32 *p = (u32 *)commit->co_verf.data;
-	*p++ = nfssvc_boot.tv_sec;
-	*p++ = nfssvc_boot.tv_usec;
-
+	gen_boot_verifier(&commit->co_verf);
 	return nfsd_commit(rqstp, &cstate->current_fh, commit->co_offset,
 			     commit->co_count);
 }
@@ -865,7 +871,6 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 {
 	stateid_t *stateid = &write->wr_stateid;
 	struct file *filp = NULL;
-	u32 *p;
 	__be32 status = nfs_ok;
 	unsigned long cnt;
 
@@ -887,9 +892,7 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 
 	cnt = write->wr_buflen;
 	write->wr_how_written = write->wr_stable_how;
-	p = (u32 *)write->wr_verifier.data;
-	*p++ = nfssvc_boot.tv_sec;
-	*p++ = nfssvc_boot.tv_usec;
+	gen_boot_verifier(&write->wr_verifier);
 
 	status =  nfsd_write(rqstp, &cstate->current_fh, filp,
 			     write->wr_offset, rqstp->rq_vec, write->wr_vlen,
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index c5cddd6..9f0e139 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1138,12 +1138,12 @@ static void gen_clid(struct nfs4_client *clp)
 
 static void gen_confirm(struct nfs4_client *clp)
 {
+	__be32 verf[2];
 	static u32 i;
-	u32 *p;
 
-	p = (u32 *)clp->cl_confirm.data;
-	*p++ = get_seconds();
-	*p++ = i++;
+	verf[0] = (__be32)get_seconds();
+	verf[1] = (__be32)i++;
+	memcpy(clp->cl_confirm.data, verf, sizeof(clp->cl_confirm.data));
 }
 
 static struct nfs4_stid *find_stateid(struct nfs4_client *cl, stateid_t *t)
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 0ec5a1b..1701ad6 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -755,14 +755,14 @@ nfsd4_decode_open(struct nfsd4_compoundargs *argp, struct nfsd4_open *open)
 				goto out;
 			break;
 		case NFS4_CREATE_EXCLUSIVE:
-			READ_BUF(8);
-			COPYMEM(open->op_verf.data, 8);
+			READ_BUF(NFS4_VERIFIER_SIZE);
+			COPYMEM(open->op_verf.data, NFS4_VERIFIER_SIZE);
 			break;
 		case NFS4_CREATE_EXCLUSIVE4_1:
 			if (argp->minorversion < 1)
 				goto xdr_error;
-			READ_BUF(8);
-			COPYMEM(open->op_verf.data, 8);
+			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);
 			if (status)
@@ -994,8 +994,8 @@ nfsd4_decode_setclientid(struct nfsd4_compoundargs *argp, struct nfsd4_setclient
 {
 	DECODE_HEAD;
 
-	READ_BUF(8);
-	COPYMEM(setclientid->se_verf.data, 8);
+	READ_BUF(NFS4_VERIFIER_SIZE);
+	COPYMEM(setclientid->se_verf.data, NFS4_VERIFIER_SIZE);
 
 	status = nfsd4_decode_opaque(argp, &setclientid->se_name);
 	if (status)
@@ -1020,9 +1020,9 @@ nfsd4_decode_setclientid_confirm(struct nfsd4_compoundargs *argp, struct nfsd4_s
 {
 	DECODE_HEAD;
 
-	READ_BUF(8 + sizeof(nfs4_verifier));
+	READ_BUF(8 + NFS4_VERIFIER_SIZE);
 	COPYMEM(&scd_c->sc_clientid, 8);
-	COPYMEM(&scd_c->sc_confirm, sizeof(nfs4_verifier));
+	COPYMEM(&scd_c->sc_confirm, NFS4_VERIFIER_SIZE);
 
 	DECODE_TAIL;
 }
@@ -2661,8 +2661,8 @@ nfsd4_encode_commit(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_
 	__be32 *p;
 
 	if (!nfserr) {
-		RESERVE_SPACE(8);
-		WRITEMEM(commit->co_verf.data, 8);
+		RESERVE_SPACE(NFS4_VERIFIER_SIZE);
+		WRITEMEM(commit->co_verf.data, NFS4_VERIFIER_SIZE);
 		ADJUST_ARGS();
 	}
 	return nfserr;
@@ -3008,7 +3008,7 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4
 	if (resp->xbuf->page_len)
 		return nfserr_resource;
 
-	RESERVE_SPACE(8);  /* verifier */
+	RESERVE_SPACE(NFS4_VERIFIER_SIZE);
 	savep = p;
 
 	/* XXX: Following NFSv3, we ignore the READDIR verifier for now. */
@@ -3209,9 +3209,9 @@ nfsd4_encode_setclientid(struct nfsd4_compoundres *resp, __be32 nfserr, struct n
 	__be32 *p;
 
 	if (!nfserr) {
-		RESERVE_SPACE(8 + sizeof(nfs4_verifier));
+		RESERVE_SPACE(8 + NFS4_VERIFIER_SIZE);
 		WRITEMEM(&scd->se_clientid, 8);
-		WRITEMEM(&scd->se_confirm, sizeof(nfs4_verifier));
+		WRITEMEM(&scd->se_confirm, NFS4_VERIFIER_SIZE);
 		ADJUST_ARGS();
 	}
 	else if (nfserr == nfserr_clid_inuse) {
@@ -3232,7 +3232,7 @@ nfsd4_encode_write(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_w
 		RESERVE_SPACE(16);
 		WRITE32(write->wr_bytes_written);
 		WRITE32(write->wr_how_written);
-		WRITEMEM(write->wr_verifier.data, 8);
+		WRITEMEM(write->wr_verifier.data, NFS4_VERIFIER_SIZE);
 		ADJUST_ARGS();
 	}
 	return nfserr;
diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
index 2364747..8d1031a 100644
--- a/fs/nfsd/xdr4.h
+++ b/fs/nfsd/xdr4.h
@@ -216,7 +216,8 @@ struct nfsd4_open {
 	u32		op_createmode;      /* request */
 	u32		op_bmval[3];        /* request */
 	struct iattr	iattr;              /* UNCHECKED4, GUARDED4, EXCLUSIVE4_1 */
-	nfs4_verifier	verf;               /* EXCLUSIVE4 */
+	nfs4_verifier	op_verf __attribute__((aligned(32)));
+					    /* EXCLUSIVE4 */
 	clientid_t	op_clientid;        /* request */
 	struct xdr_netobj op_owner;           /* request */
 	u32		op_seqid;           /* request */
@@ -234,7 +235,6 @@ struct nfsd4_open {
 	struct nfs4_acl *op_acl;
 };
 #define op_iattr	iattr
-#define op_verf		verf
 
 struct nfsd4_open_confirm {
 	stateid_t	oc_req_stateid		/* request */;