From: Chuck Lever <chuck.lever@xxxxxxxxxx>
Done as part of hardening the server-side RPC header decoding path.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
net/sunrpc/auth_gss/svcauth_gss.c | 125 ++++++++++++++++++++++---------------
1 file changed, 75 insertions(+), 50 deletions(-)
diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 363c25198547..557de28127fe 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -697,23 +697,6 @@ static inline u32 round_up_to_quad(u32 i)
return (i + 3 ) & ~3;
}
-static inline int
-svc_safe_getnetobj(struct kvec *argv, struct xdr_netobj *o)
-{
- int l;
-
- if (argv->iov_len < 4)
- return -1;
- o->len = svc_getnl(argv);
- l = round_up_to_quad(o->len);
- if (argv->iov_len < l)
- return -1;
- o->data = argv->iov_base;
- argv->iov_base += l;
- argv->iov_len -= l;
- return 0;
-}
-
static inline int
svc_safe_putnetobj(struct kvec *resv, struct xdr_netobj *o)
{
@@ -1553,27 +1536,91 @@ static void destroy_use_gss_proxy_proc_entry(struct net *net) {}
#endif /* CONFIG_PROC_FS */
/*
- * Accept an rpcsec packet.
- * If context establishment, punt to user space
- * If data exchange, verify/decrypt
- * If context destruction, handle here
- * In the context establishment and destruction case we encode
- * response here and return SVC_COMPLETE.
+ * The Call's credential body should contain a struct rpc_gss_cred_t.
+ *
+ * RFC 2203 Section 5
+ *
+ * struct rpc_gss_cred_t {
+ * union switch (unsigned int version) {
+ * case RPCSEC_GSS_VERS_1:
+ * struct {
+ * rpc_gss_proc_t gss_proc;
+ * unsigned int seq_num;
+ * rpc_gss_service_t service;
+ * opaque handle<>;
+ * } rpc_gss_cred_vers_1_t;
+ * }
+ * };
+ */
+static bool
+svcauth_gss_decode_credbody(struct xdr_stream *xdr,
+ struct rpc_gss_wire_cred *gc,
+ __be32 **rpcstart)
+{
+ ssize_t handle_len;
+ u32 body_len;
+ __be32 *p;
+
+ p = xdr_inline_decode(xdr, XDR_UNIT);
+ if (!p)
+ return false;
+ /*
+ * start of rpc packet is 7 u32's back from here:
+ * xid direction rpcversion prog vers proc flavour
+ */
+ *rpcstart = p - 7;
+ body_len = be32_to_cpup(p);
+ if (body_len > RPC_MAX_AUTH_SIZE)
+ return false;
+
+ /* struct rpc_gss_cred_t */
+ if (xdr_stream_decode_u32(xdr, &gc->gc_v) < 0)
+ return false;
+ if (xdr_stream_decode_u32(xdr, &gc->gc_proc) < 0)
+ return false;
+ if (xdr_stream_decode_u32(xdr, &gc->gc_seq) < 0)
+ return false;
+ if (xdr_stream_decode_u32(xdr, &gc->gc_svc) < 0)
+ return false;
+ handle_len = xdr_stream_decode_opaque_inline(xdr,
+ (void **)&gc->gc_ctx.data,
+ body_len);
+ if (handle_len < 0)
+ return false;
+ if (body_len != XDR_UNIT * 5 + xdr_align_size(handle_len))
+ return false;
+
+ gc->gc_ctx.len = handle_len;
+ return true;
+}
+
+/**
+ * svcauth_gss_accept - Decode and validate incoming RPC_AUTH_GSS credential
+ * @rqstp: RPC transaction
+ *
+ * Return values:
+ * %SVC_OK: Success
+ * %SVC_COMPLETE: GSS context lifetime event
+ * %SVC_DENIED: Credential or verifier is not valid
+ * %SVC_GARBAGE: Failed to decode credential or verifier
+ * %SVC_CLOSE: Temporary failure
+ *
+ * The rqstp->rq_auth_stat field is also set (see RFCs 2203 and 5531).
*/
static int
svcauth_gss_accept(struct svc_rqst *rqstp)
{
- struct kvec *argv = &rqstp->rq_arg.head[0];
struct kvec *resv = &rqstp->rq_res.head[0];
- u32 crlen;
struct gss_svc_data *svcdata = rqstp->rq_auth_data;
+ __be32 *rpcstart;
struct rpc_gss_wire_cred *gc;
struct rsc *rsci = NULL;
- __be32 *rpcstart;
__be32 *reject_stat = resv->iov_base + resv->iov_len;
int ret;
struct sunrpc_net *sn = net_generic(SVC_NET(rqstp), sunrpc_net_id);
+ svcxdr_init_decode(rqstp);
+
rqstp->rq_auth_stat = rpc_autherr_badcred;
if (!svcdata)
svcdata = kmalloc(sizeof(*svcdata), GFP_KERNEL);
@@ -1584,31 +1631,10 @@ svcauth_gss_accept(struct svc_rqst *rqstp)
svcdata->rsci = NULL;
gc = &svcdata->clcred;
- /* start of rpc packet is 7 u32's back from here:
- * xid direction rpcversion prog vers proc flavour
- */
- rpcstart = argv->iov_base;
- rpcstart -= 7;
-
- /* credential is:
- * version(==1), proc(0,1,2,3), seq, service (1,2,3), handle
- * at least 5 u32s, and is preceded by length, so that makes 6.
- */
-
- if (argv->iov_len < 5 * 4)
+ if (!svcauth_gss_decode_credbody(&rqstp->rq_arg_stream, gc, &rpcstart))
goto auth_err;
- crlen = svc_getnl(argv);
- if (svc_getnl(argv) != RPC_GSS_VERSION)
+ if (gc->gc_v != RPC_GSS_VERSION)
goto auth_err;
- gc->gc_proc = svc_getnl(argv);
- gc->gc_seq = svc_getnl(argv);
- gc->gc_svc = svc_getnl(argv);
- if (svc_safe_getnetobj(argv, &gc->gc_ctx))
- goto auth_err;
- if (crlen != round_up_to_quad(gc->gc_ctx.len) + 5 * 4)
- goto auth_err;
-
- svcxdr_init_decode(rqstp);
switch (gc->gc_proc) {
case RPC_GSS_PROC_INIT:
@@ -1621,7 +1647,6 @@ svcauth_gss_accept(struct svc_rqst *rqstp)
goto auth_err;
fallthrough;
case RPC_GSS_PROC_DATA:
- /* Look up the context, and check the verifier: */
rqstp->rq_auth_stat = rpcsec_gsserr_credproblem;
rsci = gss_svc_searchbyctx(sn->rsc_cache, &gc->gc_ctx);
if (!rsci)
