rpc: comment on linux_cred encoding, treat all as unsigned

The encoding of linux creds is a bit confusing.

Also: I think in practice it doesn't really matter whether we treat any
of these things as signed or unsigned, but unsigned seems more
straightforward: uid_t/gid_t are unsigned and it simplifies the ngroups
overflow check.

Tested-by: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 10 insertions, 8 deletions

diff --git a/net/sunrpc/auth_gss/gss_rpc_xdr.c b/net/sunrpc/auth_gss/gss_rpc_xdr.c
index f5067b2e0a08..3c19c7d48899 100644
--- a/net/sunrpc/auth_gss/gss_rpc_xdr.c
+++ b/net/sunrpc/auth_gss/gss_rpc_xdr.c
@@ -166,14 +166,15 @@ static int dummy_dec_opt_array(struct xdr_stream *xdr,
         return 0;
 }
 
-static int get_s32(struct xdr_stream *xdr, s32 *res)
+static int get_host_u32(struct xdr_stream *xdr, u32 *res)
 {
         __be32 *p;
 
         p = xdr_inline_decode(xdr, 4);
         if (!p)
                 return -EINVAL;
-        memcpy(res, p, sizeof(s32));
+        /* Contents of linux creds are all host-endian: */
+        memcpy(res, p, sizeof(u32));
         return 0;
 }
 
@@ -182,8 +183,9 @@ static int gssx_dec_linux_creds(struct xdr_stream *xdr,
 {
         u32 length;
         __be32 *p;
-        s32 tmp;
-        int N, i, err;
+        u32 tmp;
+        u32 N;
+        int i, err;
 
         p = xdr_inline_decode(xdr, 4);
         if (unlikely(p == NULL))
@@ -195,19 +197,19 @@ static int gssx_dec_linux_creds(struct xdr_stream *xdr,
                 return -ENOSPC;
 
         /* uid */
-        err = get_s32(xdr, &tmp);
+        err = get_host_u32(xdr, &tmp);
         if (err)
                 return err;
         creds->cr_uid = make_kuid(&init_user_ns, tmp);
 
         /* gid */
-        err = get_s32(xdr, &tmp);
+        err = get_host_u32(xdr, &tmp);
         if (err)
                 return err;
         creds->cr_gid = make_kgid(&init_user_ns, tmp);
 
         /* number of additional gid's */
-        err = get_s32(xdr, &tmp);
+        err = get_host_u32(xdr, &tmp);
         if (err)
                 return err;
         N = tmp;
@@ -220,7 +222,7 @@ static int gssx_dec_linux_creds(struct xdr_stream *xdr,
         /* gid's */
         for (i = 0; i < N; i++) {
                 kgid_t kgid;
-                err = get_s32(xdr, &tmp);
+                err = get_host_u32(xdr, &tmp);
                 if (err)
                         goto out_free_groups;
                 err = -EINVAL;