[ 45/49] rpc: clean up decoding of gssproxy linux creds

Greg Kroah-Hartman
2013-09-29T19:50:52Z

From: "J. Bruce Fields" <bfields@redhat.com>

commit 778e512bb1d3315c6b55832248cd30c566c081d7 upstream.

We can use the normal coding infrastructure here.

Two minor behavior changes:

- we're assuming no wasted space at the end of the linux cred.
That seems to match gss-proxy's behavior, and I can't see why
it would need to do differently in the future.

- NGROUPS_MAX check added: note groups_alloc doesn't do this,
this is the caller's responsibility.

Tested-by: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/sunrpc/auth_gss/gss_rpc_xdr.c | 32 +++++++++++++-------------------
1 file changed, 13 insertions(+), 19 deletions(-)

--- a/net/sunrpc/auth_gss/gss_rpc_xdr.c
+++ b/net/sunrpc/auth_gss/gss_rpc_xdr.c
@@ -166,14 +166,14 @@ static int dummy_dec_opt_array(struct xd
return 0;
}

-static int get_s32(void **p, void *max, s32 *res)
+static int get_s32(struct xdr_stream *xdr, s32 *res)
{
- void *base = *p;
- void *next = (void *)((char *)base + sizeof(s32));
- if (unlikely(next > max || next < base))
+ __be32 *p;
+
+ p = xdr_inline_decode(xdr, 4);
+ if (!p)
return -EINVAL;
- memcpy(res, base, sizeof(s32));
- *p = next;
+ memcpy(res, p, sizeof(s32));
return 0;
}

@@ -182,7 +182,6 @@ static int gssx_dec_linux_creds(struct x
{
u32 length;
__be32 *p;
- void *q, *end;
s32 tmp;
int N, i, err;

@@ -192,33 +191,28 @@ static int gssx_dec_linux_creds(struct x

length = be32_to_cpup(p);

- /* FIXME: we do not want to use the scratch buffer for this one
- * may need to use functions that allows us to access an io vector
- * directly */
- p = xdr_inline_decode(xdr, length);
- if (unlikely(p == NULL))
+ if (length > (3 + NGROUPS_MAX) * sizeof(u32))
return -ENOSPC;

- q = p;
- end = q + length;
-
/* uid */
- err = get_s32(&q, end, &tmp);
+ err = get_s32(xdr, &tmp);
if (err)
return err;
creds->cr_uid = make_kuid(&init_user_ns, tmp);

/* gid */
- err = get_s32(&q, end, &tmp);
+ err = get_s32(xdr, &tmp);
if (err)
return err;
creds->cr_gid = make_kgid(&init_user_ns, tmp);

/* number of additional gid's */
- err = get_s32(&q, end, &tmp);
+ err = get_s32(xdr, &tmp);
if (err)
return err;
N = tmp;
+ if ((3 + N) * sizeof(u32) != length)
+ return -EINVAL;
creds->cr_group_info = groups_alloc(N);
if (creds->cr_group_info == NULL)
return -ENOMEM;
@@ -226,7 +220,7 @@ static int gssx_dec_linux_creds(struct x
/* gid's */
for (i = 0; i < N; i++) {
kgid_t kgid;
- err = get_s32(&q, end, &tmp);
+ err = get_s32(xdr, &tmp);
if (err)
goto out_free_groups;
err = -EINVAL;