* [PATCH V3 2/2] SUNRPC: Rename xdr_buf_read_netobj to xdr_buf_read_mic
2019-09-16 11:59 [PATCH V3 1/2] SUNRPC: Fix buffer handling of GSS MIC without slack Benjamin Coddington
@ 2019-09-16 11:59 ` Benjamin Coddington
2019-09-16 14:43 ` [PATCH V3 1/2] SUNRPC: Fix buffer handling of GSS MIC without slack Chuck Lever
1 sibling, 0 replies; 3+ messages in thread
From: Benjamin Coddington @ 2019-09-16 11:59 UTC (permalink / raw)
To: trond.myklebust, anna.schumaker, tibbs, chuck.lever
Cc: linux-nfs, bfields, km
Let the name reflect the single use. The function now assumes the GSS MIC
is the last object in the buffer.
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
---
include/linux/sunrpc/xdr.h | 2 +-
net/sunrpc/auth_gss/auth_gss.c | 2 +-
net/sunrpc/xdr.c | 52 ++++++++++++++++++++--------------
3 files changed, 32 insertions(+), 24 deletions(-)
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index 8a87d8bcb197..f33e5013bdfb 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -186,7 +186,7 @@ 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 int xdr_buf_read_netobj(struct xdr_buf *, struct xdr_netobj *, 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/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 4ce42c62458e..d75fddca44c9 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -1960,7 +1960,7 @@ gss_unwrap_resp_integ(struct rpc_task *task, struct rpc_cred *cred,
if (xdr_buf_subsegment(rcv_buf, &integ_buf, data_offset, integ_len))
goto unwrap_failed;
- if (xdr_buf_read_netobj(rcv_buf, &mic, mic_offset))
+ if (xdr_buf_read_mic(rcv_buf, &mic, mic_offset))
goto unwrap_failed;
maj_stat = gss_verify_mic(ctx->gc_gss_ctx, &integ_buf, &mic);
if (maj_stat == GSS_S_CONTEXT_EXPIRED)
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index b256806d69cd..74ae4c54b51a 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -1236,52 +1236,60 @@ xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
}
EXPORT_SYMBOL_GPL(xdr_encode_word);
-/* If the netobj starting offset bytes from the start of xdr_buf is contained
- * entirely in the head, pages, or tail, set object to point to it; otherwise
- * shift the buffer until it is contained entirely within the pages or tail.
+/**
+ * xdr_buf_read_mic() - obtain the address of the GSS mic from xdr buf
+ * @buf: pointer to buffer containing a mic
+ * @mic: on success, returns the address of the mic
+ * @offset: the offset in buf where mic may be found
+ *
+ * This function may modify the xdr buf if the mic is found to be straddling
+ * a boundary between head, pages, and tail. On success the mic can be read
+ * from the address returned. There is no need to free the mic.
+ *
+ * Return: Success returns 0, otherwise an integer error.
*/
-int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
+int xdr_buf_read_mic(struct xdr_buf *buf, struct xdr_netobj *mic, unsigned int offset)
{
struct xdr_buf subbuf;
unsigned int boundary;
- if (xdr_decode_word(buf, offset, &obj->len))
+ if (xdr_decode_word(buf, offset, &mic->len))
return -EFAULT;
offset += 4;
- /* Is the obj partially in the head? */
+ /* Is the mic partially in the head? */
boundary = buf->head[0].iov_len;
- if (offset < boundary && (offset + obj->len) > boundary)
+ if (offset < boundary && (offset + mic->len) > boundary)
xdr_shift_buf(buf, boundary - offset);
- /* Is the obj partially in the pages? */
+ /* Is the mic partially in the pages? */
boundary += buf->page_len;
- if (offset < boundary && (offset + obj->len) > boundary)
+ if (offset < boundary && (offset + mic->len) > boundary)
xdr_shrink_pagelen(buf, boundary - offset);
- if (xdr_buf_subsegment(buf, &subbuf, offset, obj->len))
+ if (xdr_buf_subsegment(buf, &subbuf, offset, mic->len))
return -EFAULT;
- /* Is the obj contained entirely in the head? */
- obj->data = subbuf.head[0].iov_base;
- if (subbuf.head[0].iov_len == obj->len)
+ /* Is the mic contained entirely in the head? */
+ mic->data = subbuf.head[0].iov_base;
+ if (subbuf.head[0].iov_len == mic->len)
return 0;
- /* ..or is the obj contained entirely in the tail? */
- obj->data = subbuf.tail[0].iov_base;
- if (subbuf.tail[0].iov_len == obj->len)
+ /* ..or is the mic contained entirely in the tail? */
+ mic->data = subbuf.tail[0].iov_base;
+ if (subbuf.tail[0].iov_len == mic->len)
return 0;
- /* Find a contiguous area in @buf to hold all of @obj */
- if (obj->len > buf->buflen - buf->len)
+ /* Find a contiguous area in @buf to hold all of @mic */
+ if (mic->len > buf->buflen - buf->len)
return -ENOMEM;
if (buf->tail[0].iov_len != 0)
- obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
+ mic->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
else
- obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
- __read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
+ mic->data = buf->head[0].iov_base + buf->head[0].iov_len;
+ __read_bytes_from_xdr_buf(&subbuf, mic->data, mic->len);
return 0;
}
-EXPORT_SYMBOL_GPL(xdr_buf_read_netobj);
+EXPORT_SYMBOL_GPL(xdr_buf_read_mic);
/* Returns 0 on success, or else a negative error code. */
static int
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH V3 1/2] SUNRPC: Fix buffer handling of GSS MIC without slack
2019-09-16 11:59 [PATCH V3 1/2] SUNRPC: Fix buffer handling of GSS MIC without slack Benjamin Coddington
2019-09-16 11:59 ` [PATCH V3 2/2] SUNRPC: Rename xdr_buf_read_netobj to xdr_buf_read_mic Benjamin Coddington
@ 2019-09-16 14:43 ` Chuck Lever
1 sibling, 0 replies; 3+ messages in thread
From: Chuck Lever @ 2019-09-16 14:43 UTC (permalink / raw)
To: Benjamin Coddington
Cc: trond.myklebust, Anna Schumaker, tibbs, Linux NFS Mailing List,
Bruce Fields, km
> On Sep 16, 2019, at 7:59 AM, Benjamin Coddington <bcodding@redhat.com> wrote:
>
> The GSS Message Integrity Check data for krb5i may lie partially in the XDR
> reply buffer's pages and tail. If so, we try to copy the entire MIC into
> free space in the tail. But as the estimations of the slack space required
> for authentication and verification have improved there may be less free
> space in the tail to complete this copy -- see commit 2c94b8eca1a2
> ("SUNRPC: Use au_rslack when computing reply buffer size"). In fact, there
> may only be room in the tail for a single copy of the MIC, and not part of
> the MIC and then another complete copy.
>
> The real world failure reported is that `ls` of a directory on NFS may
> sometimes return -EIO, which can be traced back to xdr_buf_read_netobj()
> failing to find available free space in the tail to copy the MIC.
>
> Fix this by checking for the case of the MIC crossing the boundaries of
> head, pages, and tail. If so, shift the buffer until the MIC is contained
> completely within the pages or tail. This allows the remainder of the
> function to create a sub buffer that directly address the complete MIC.
>
> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
> Cc: stable@vger.kernel.org # v5.1
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
> ---
> net/sunrpc/xdr.c | 27 ++++++++++++++++++---------
> 1 file changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
> index 48c93b9e525e..b256806d69cd 100644
> --- a/net/sunrpc/xdr.c
> +++ b/net/sunrpc/xdr.c
> @@ -1237,16 +1237,29 @@ xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
> EXPORT_SYMBOL_GPL(xdr_encode_word);
>
> /* If the netobj starting offset bytes from the start of xdr_buf is contained
> - * entirely in the head or the tail, set object to point to it; otherwise
> - * try to find space for it at the end of the tail, copy it there, and
> - * set obj to point to it. */
> + * entirely in the head, pages, or tail, set object to point to it; otherwise
> + * shift the buffer until it is contained entirely within the pages or tail.
> + */
> int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
> {
> struct xdr_buf subbuf;
> + unsigned int boundary;
>
> if (xdr_decode_word(buf, offset, &obj->len))
> return -EFAULT;
> - if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
> + offset += 4;
> +
> + /* Is the obj partially in the head? */
> + boundary = buf->head[0].iov_len;
> + if (offset < boundary && (offset + obj->len) > boundary)
> + xdr_shift_buf(buf, boundary - offset);
> +
> + /* Is the obj partially in the pages? */
> + boundary += buf->page_len;
> + if (offset < boundary && (offset + obj->len) > boundary)
> + xdr_shrink_pagelen(buf, boundary - offset);
> +
> + if (xdr_buf_subsegment(buf, &subbuf, offset, obj->len))
> return -EFAULT;
>
> /* Is the obj contained entirely in the head? */
> @@ -1258,11 +1271,7 @@ int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned in
> if (subbuf.tail[0].iov_len == obj->len)
> return 0;
>
> - /* use end of tail as storage for obj:
> - * (We don't copy to the beginning because then we'd have
> - * to worry about doing a potentially overlapping copy.
> - * This assumes the object is at most half the length of the
> - * tail.) */
> + /* Find a contiguous area in @buf to hold all of @obj */
> if (obj->len > buf->buflen - buf->len)
> return -ENOMEM;
> if (buf->tail[0].iov_len != 0)
> --
> 2.20.1
>
--
Chuck Lever
^ permalink raw reply [flat|nested] 3+ messages in thread