[PATCH AUTOSEL 5.6 007/606] NFSv3: fix rpc receive buffer size for MOUNT call

[PATCH AUTOSEL 5.6 007/606] NFSv3: fix rpc receive buffer size for MOUNT call

[Sasha Levin]

From: Olga Kornievskaia <olga.kornievskaia@gmail.com>

[ Upstream commit 8eed292bc8cbf737e46fb1c119d4c8f6dcb00650 ]

Prior to commit e3d3ab64dd66 ("SUNRPC: Use au_rslack when
computing reply buffer size"), there was enough slack in the reply
buffer to commodate filehandles of size 60bytes. However, the real
problem was that the reply buffer size for the MOUNT operation was
not correctly calculated. Received buffer size used the filehandle
size for NFSv2 (32bytes) which is much smaller than the allowed
filehandle size for the v3 mounts.

Fix the reply buffer size (decode arguments size) for the MNT command.

Fixes: 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing reply buffer size")
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/nfs/mount_clnt.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/mount_clnt.c b/fs/nfs/mount_clnt.c
index 35c8cb2d7637..dda5c3e65d8d 100644
--- a/fs/nfs/mount_clnt.c
+++ b/fs/nfs/mount_clnt.c
@@ -30,6 +30,7 @@
 #define encode_dirpath_sz	(1 + XDR_QUADLEN(MNTPATHLEN))
 #define MNT_status_sz		(1)
 #define MNT_fhandle_sz		XDR_QUADLEN(NFS2_FHSIZE)
+#define MNT_fhandlev3_sz	XDR_QUADLEN(NFS3_FHSIZE)
 #define MNT_authflav3_sz	(1 + NFS_MAX_SECFLAVORS)
 
 /*
@@ -37,7 +38,7 @@
  */
 #define MNT_enc_dirpath_sz	encode_dirpath_sz
 #define MNT_dec_mountres_sz	(MNT_status_sz + MNT_fhandle_sz)
-#define MNT_dec_mountres3_sz	(MNT_status_sz + MNT_fhandle_sz + \
+#define MNT_dec_mountres3_sz	(MNT_status_sz + MNT_fhandlev3_sz + \
 				 MNT_authflav3_sz)
 
 /*
-- 
2.25.1

[PATCH AUTOSEL 5.6 067/606] SUNRPC: Revert 241b1f419f0e ("SUNRPC: Remove xdr_buf_trim()")

[Sasha Levin]

From: Chuck Lever <chuck.lever@oracle.com>

commit 0a8e7b7d08466b5fc52f8e96070acc116d82a8bb upstream.

I've noticed that when krb5i or krb5p security is in use,
retransmitted requests are missing the server's duplicate reply
cache. The computed checksum on the retransmitted request does not
match the cached checksum, resulting in the server performing the
retransmitted request again instead of returning the cached reply.

The assumptions made when removing xdr_buf_trim() were not correct.
In the send paths, the upper layer has already set the segment
lengths correctly, and shorting the buffer's content is simply a
matter of reducing buf->len.

xdr_buf_trim() is the right answer in the receive/unwrap path on
both the client and the server. The buffer segment lengths have to
be shortened one-by-one.

On the server side in particular, head.iov_len needs to be updated
correctly to enable nfsd_cache_csum() to work correctly. The simple
buf->len computation doesn't do that, and that results in
checksumming stale data in the buffer.

The problem isn't noticed until there's significant instability of
the RPC transport. At that point, the reliability of retransmit
detection on the server becomes crucial.

Fixes: 241b1f419f0e ("SUNRPC: Remove xdr_buf_trim()")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/linux/sunrpc/xdr.h          |  1 +
 net/sunrpc/auth_gss/gss_krb5_wrap.c |  7 +++--
 net/sunrpc/auth_gss/svcauth_gss.c   |  2 +-
 net/sunrpc/xdr.c                    | 41 +++++++++++++++++++++++++++++
 4 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index b41f34977995..ae2b1449dc09 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -184,6 +184,7 @@ xdr_adjust_iovec(struct kvec *iov, __be32 *p)
 extern void xdr_shift_buf(struct xdr_buf *, size_t);
 extern void xdr_buf_from_iov(struct kvec *, struct xdr_buf *);
 extern int xdr_buf_subsegment(struct xdr_buf *, struct xdr_buf *, unsigned int, unsigned int);
+extern void xdr_buf_trim(struct xdr_buf *, unsigned int);
 extern int xdr_buf_read_mic(struct xdr_buf *, struct xdr_netobj *, unsigned int);
 extern int read_bytes_from_xdr_buf(struct xdr_buf *, unsigned int, void *, unsigned int);
 extern int write_bytes_to_xdr_buf(struct xdr_buf *, unsigned int, void *, unsigned int);
diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c
index 4905652e7567..cf0fd170ac18 100644
--- a/net/sunrpc/auth_gss/gss_krb5_wrap.c
+++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
@@ -580,15 +580,14 @@ gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len,
 	 */
 	movelen = min_t(unsigned int, buf->head[0].iov_len, len);
 	movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;
-	if (offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >
-	    buf->head[0].iov_len)
-		return GSS_S_FAILURE;
+	BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >
+							buf->head[0].iov_len);
 	memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen);
 	buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;
 	buf->len = len - GSS_KRB5_TOK_HDR_LEN + headskip;
 
 	/* Trim off the trailing "extra count" and checksum blob */
-	buf->len -= ec + GSS_KRB5_TOK_HDR_LEN + tailskip;
+	xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
 
 	*align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip);
 	*slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 559053646e12..322fd48887f9 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -900,7 +900,7 @@ unwrap_integ_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct g
 	if (svc_getnl(&buf->head[0]) != seq)
 		goto out;
 	/* trim off the mic and padding at the end before returning */
-	buf->len -= 4 + round_up_to_quad(mic.len);
+	xdr_buf_trim(buf, round_up_to_quad(mic.len) + 4);
 	stat = 0;
 out:
 	kfree(mic.data);
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index e5497dc2475b..f6da616267ce 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -1150,6 +1150,47 @@ xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
 }
 EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
 
+/**
+ * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
+ * @buf: buf to be trimmed
+ * @len: number of bytes to reduce "buf" by
+ *
+ * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
+ * that it's possible that we'll trim less than that amount if the xdr_buf is
+ * too small, or if (for instance) it's all in the head and the parser has
+ * already read too far into it.
+ */
+void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
+{
+	size_t cur;
+	unsigned int trim = len;
+
+	if (buf->tail[0].iov_len) {
+		cur = min_t(size_t, buf->tail[0].iov_len, trim);
+		buf->tail[0].iov_len -= cur;
+		trim -= cur;
+		if (!trim)
+			goto fix_len;
+	}
+
+	if (buf->page_len) {
+		cur = min_t(unsigned int, buf->page_len, trim);
+		buf->page_len -= cur;
+		trim -= cur;
+		if (!trim)
+			goto fix_len;
+	}
+
+	if (buf->head[0].iov_len) {
+		cur = min_t(size_t, buf->head[0].iov_len, trim);
+		buf->head[0].iov_len -= cur;
+		trim -= cur;
+	}
+fix_len:
+	buf->len -= (len - trim);
+}
+EXPORT_SYMBOL_GPL(xdr_buf_trim);
+
 static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
 {
 	unsigned int this_len;
-- 
2.25.1