SUNRPC: Add rpc_auth::au_ralign field

Currently rpc_inline_rcv_pages() uses au_rslack to estimate the
size of the upper layer reply header. This is fine for auth flavors
where au_verfsize == au_rslack.

However, some auth flavors have more going on. krb5i for example has
two more words after the verifier, and another blob following the
RPC message. The calculation involving au_rslack pushes the upper
layer reply header too far into the rcv_buf.

au_rslack is still valuable: it's the amount of buffer space needed
for the reply, and is used when allocating the reply buffer. We'll
keep that.

But, add a new field that can be used to properly estimate the
location of the upper layer header in each RPC reply, based on the
auth flavor in use.

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

5 files changed, 20 insertions, 11 deletions

diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h
index 359dfdd04e77..5f9076fdb090 100644
--- a/include/linux/sunrpc/auth.h
+++ b/include/linux/sunrpc/auth.h
@@ -74,13 +74,12 @@ struct rpc_cred_cache;
 struct rpc_authops;
 struct rpc_auth {
         unsigned int            au_cslack;      /* call cred size estimate */
-                                /* guess at number of u32's auth adds before
-                                 * reply data; normally the verifier size: */
-        unsigned int            au_rslack;
+        unsigned int            au_rslack;      /* reply cred size estimate */
         unsigned int            au_verfsize;    /* size of reply verifier */
+        unsigned int            au_ralign;      /* words before UL header */
 
-        unsigned int            au_flags;       /* various flags */
-        const struct rpc_authops *au_ops;               /* operations */
+        unsigned int            au_flags;
+        const struct rpc_authops *au_ops;
         rpc_authflavor_t        au_flavor;      /* pseudoflavor (note may
                                                  * differ from the flavor in
                                                  * au_ops->au_flavor in gss
diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 731e7a482e18..c67e2ad151ae 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -1017,6 +1017,7 @@ gss_create_new(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
         auth->au_cslack = GSS_CRED_SLACK >> 2;
         auth->au_rslack = GSS_VERF_SLACK >> 2;
         auth->au_verfsize = GSS_VERF_SLACK >> 2;
+        auth->au_ralign = GSS_VERF_SLACK >> 2;
         auth->au_flags = 0;
         auth->au_ops = &authgss_ops;
         auth->au_flavor = flavor;
@@ -1891,7 +1892,10 @@ out:
 static int
 gss_unwrap_resp_auth(struct rpc_cred *cred)
 {
-        cred->cr_auth->au_rslack = cred->cr_auth->au_verfsize;
+        struct rpc_auth *auth = cred->cr_auth;
+
+        auth->au_rslack = auth->au_verfsize;
+        auth->au_ralign = auth->au_verfsize;
         return 0;
 }
 
@@ -1902,6 +1906,7 @@ gss_unwrap_resp_integ(struct rpc_task *task, struct rpc_cred *cred,
 {
         struct xdr_buf integ_buf, *rcv_buf = &rqstp->rq_rcv_buf;
         u32 data_offset, mic_offset, integ_len, maj_stat;
+        struct rpc_auth *auth = cred->cr_auth;
         struct xdr_netobj mic;
         __be32 *p;
 
@@ -1928,8 +1933,8 @@ gss_unwrap_resp_integ(struct rpc_task *task, struct rpc_cred *cred,
         if (maj_stat != GSS_S_COMPLETE)
                 goto bad_mic;
 
-        cred->cr_auth->au_rslack = cred->cr_auth->au_verfsize + 2 +
-                                   1 + XDR_QUADLEN(mic.len);
+        auth->au_rslack = auth->au_verfsize + 2 + 1 + XDR_QUADLEN(mic.len);
+        auth->au_ralign = auth->au_verfsize + 2;
         return 0;
 unwrap_failed:
         trace_rpcgss_unwrap_failed(task);
@@ -1949,6 +1954,7 @@ gss_unwrap_resp_priv(struct rpc_task *task, struct rpc_cred *cred,
 {
         struct xdr_buf *rcv_buf = &rqstp->rq_rcv_buf;
         struct kvec *head = rqstp->rq_rcv_buf.head;
+        struct rpc_auth *auth = cred->cr_auth;
         unsigned int savedlen = rcv_buf->len;
         u32 offset, opaque_len, maj_stat;
         __be32 *p;
@@ -1976,8 +1982,10 @@ gss_unwrap_resp_priv(struct rpc_task *task, struct rpc_cred *cred,
          */
         xdr_init_decode(xdr, rcv_buf, p, rqstp);
 
-        cred->cr_auth->au_rslack = cred->cr_auth->au_verfsize + 2 +
-                                   XDR_QUADLEN(savedlen - rcv_buf->len);
+        auth->au_rslack = auth->au_verfsize + 2 +
+                          XDR_QUADLEN(savedlen - rcv_buf->len);
+        auth->au_ralign = auth->au_verfsize + 2 +
+                          XDR_QUADLEN(savedlen - rcv_buf->len);
         return 0;
 unwrap_failed:
         trace_rpcgss_unwrap_failed(task);
diff --git a/net/sunrpc/auth_null.c b/net/sunrpc/auth_null.c
index 9ae08248a9e1..41a633a4049e 100644
--- a/net/sunrpc/auth_null.c
+++ b/net/sunrpc/auth_null.c
@@ -115,6 +115,7 @@ struct rpc_auth null_auth = {
         .au_cslack      = NUL_CALLSLACK,
         .au_rslack      = NUL_REPLYSLACK,
         .au_verfsize    = NUL_REPLYSLACK,
+        .au_ralign      = NUL_REPLYSLACK,
         .au_ops         = &authnull_ops,
         .au_flavor      = RPC_AUTH_NULL,
         .au_count       = REFCOUNT_INIT(1),
diff --git a/net/sunrpc/auth_unix.c b/net/sunrpc/auth_unix.c
index a93c56442487..c048eb6deaaf 100644
--- a/net/sunrpc/auth_unix.c
+++ b/net/sunrpc/auth_unix.c
@@ -187,6 +187,7 @@ unx_validate(struct rpc_task *task, struct xdr_stream *xdr)
 
         auth->au_verfsize = XDR_QUADLEN(size) + 2;
         auth->au_rslack = XDR_QUADLEN(size) + 2;
+        auth->au_ralign = XDR_QUADLEN(size) + 2;
         return 0;
 }
 
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 4ea38b029e2f..99bfeb17367c 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -1180,7 +1180,7 @@ void rpc_prepare_reply_pages(struct rpc_rqst *req, struct page **pages,
         /* Subtract one to force an extra word of buffer space for the
          * payload's XDR pad to fall into the rcv_buf's tail iovec.
          */
-        hdrsize += RPC_REPHDRSIZE + req->rq_cred->cr_auth->au_rslack - 1;
+        hdrsize += RPC_REPHDRSIZE + req->rq_cred->cr_auth->au_ralign - 1;
 
         xdr_inline_pages(&req->rq_rcv_buf, hdrsize << 2, pages, base, len);
         trace_rpc_reply_pages(req);