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SUNRPC: Convert the svcauth_gss_accept() pre-amble to use xdr_stream

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Done as part of hardening the server-side RPC header decoding path.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2023-01-02 12:07:26 -05:00
parent 6734706bc0
commit b0bc53470d
1 changed files with 75 additions and 50 deletions
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125
net/sunrpc/auth_gss/svcauth_gss.c
View file

@ -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)