From 6181b0c6432bf0807512e85e0c5863f7aca8e515 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Mon, 2 Jan 2023 12:05:56 -0500 Subject: SUNRPC: Convert svcauth_unix_accept() to use xdr_stream Done as part of hardening the server-side RPC header decoding path. Since the server-side of the Linux kernel SunRPC implementation ignores the contents of the Call's machinename field, there's no need for its RPC_AUTH_UNIX authenticator to reject names that are larger than UNX_MAXNODENAME. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever --- net/sunrpc/svcauth_unix.c | 71 ++++++++++++++++++++++++++++++++++------------- 1 file changed, 51 insertions(+), 20 deletions(-) (limited to 'net/sunrpc/svcauth_unix.c') diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c index 95354f03bb05..b6aef9c5113b 100644 --- a/net/sunrpc/svcauth_unix.c +++ b/net/sunrpc/svcauth_unix.c @@ -867,26 +867,45 @@ struct auth_ops svcauth_tls = { }; +/** + * svcauth_unix_accept - Decode and validate incoming RPC_AUTH_SYS credential + * @rqstp: RPC transaction + * + * Return values: + * %SVC_OK: Both credential and verifier are valid + * %SVC_DENIED: Credential or verifier is not valid + * %SVC_GARBAGE: Failed to decode credential or verifier + * %SVC_CLOSE: Temporary failure + * + * rqstp->rq_auth_stat is set as mandated by RFC 5531. + */ static int svcauth_unix_accept(struct svc_rqst *rqstp) { - struct kvec *argv = &rqstp->rq_arg.head[0]; struct kvec *resv = &rqstp->rq_res.head[0]; + struct xdr_stream *xdr = &rqstp->rq_arg_stream; struct svc_cred *cred = &rqstp->rq_cred; struct user_namespace *userns; - u32 slen, i; - int len = argv->iov_len; + u32 flavor, len, i; + void *body; + __be32 *p; + + svcxdr_init_decode(rqstp); - if ((len -= 3*4) < 0) + /* + * This implementation ignores the length of the Call's + * credential body field and the timestamp and machinename + * fields. + */ + p = xdr_inline_decode(xdr, XDR_UNIT * 3); + if (!p) + return SVC_GARBAGE; + len = be32_to_cpup(p + 2); + if (len > RPC_MAX_MACHINENAME) + return SVC_GARBAGE; + if (!xdr_inline_decode(xdr, len)) return SVC_GARBAGE; - svc_getu32(argv); /* length */ - svc_getu32(argv); /* time stamp */ - slen = XDR_QUADLEN(svc_getnl(argv)); /* machname length */ - if (slen > 64 || (len -= (slen + 3)*4) < 0) - goto badcred; - argv->iov_base = (void*)((__be32*)argv->iov_base + slen); /* skip machname */ - argv->iov_len -= slen*4; /* * Note: we skip uid_valid()/gid_valid() checks here for * backwards compatibility with clients that use -1 id's. @@ -896,20 +915,33 @@ svcauth_unix_accept(struct svc_rqst *rqstp) */ userns = (rqstp->rq_xprt && rqstp->rq_xprt->xpt_cred) ? rqstp->rq_xprt->xpt_cred->user_ns : &init_user_ns; - cred->cr_uid = make_kuid(userns, svc_getnl(argv)); /* uid */ - cred->cr_gid = make_kgid(userns, svc_getnl(argv)); /* gid */ - slen = svc_getnl(argv); /* gids length */ - if (slen > UNX_NGROUPS || (len -= (slen + 2)*4) < 0) + if (xdr_stream_decode_u32(xdr, &i) < 0) + return SVC_GARBAGE; + cred->cr_uid = make_kuid(userns, i); + if (xdr_stream_decode_u32(xdr, &i) < 0) + return SVC_GARBAGE; + cred->cr_gid = make_kgid(userns, i); + + if (xdr_stream_decode_u32(xdr, &len) < 0) + return SVC_GARBAGE; + if (len > UNX_NGROUPS) goto badcred; - cred->cr_group_info = groups_alloc(slen); + p = xdr_inline_decode(xdr, XDR_UNIT * len); + if (!p) + return SVC_GARBAGE; + cred->cr_group_info = groups_alloc(len); if (cred->cr_group_info == NULL) return SVC_CLOSE; - for (i = 0; i < slen; i++) { - kgid_t kgid = make_kgid(userns, svc_getnl(argv)); + for (i = 0; i < len; i++) { + kgid_t kgid = make_kgid(userns, be32_to_cpup(p++)); cred->cr_group_info->gid[i] = kgid; } groups_sort(cred->cr_group_info); - if (svc_getu32(argv) != htonl(RPC_AUTH_NULL) || svc_getu32(argv) != 0) { + + /* Call's verf field: */ + if (xdr_stream_decode_opaque_auth(xdr, &flavor, &body, &len) < 0) + return SVC_GARBAGE; + if (flavor != RPC_AUTH_NULL || len != 0) { rqstp->rq_auth_stat = rpc_autherr_badverf; return SVC_DENIED; } @@ -919,7 +951,6 @@ svcauth_unix_accept(struct svc_rqst *rqstp) svc_putnl(resv, 0); rqstp->rq_cred.cr_flavor = RPC_AUTH_UNIX; - svcxdr_init_decode(rqstp); return SVC_OK; badcred: -- cgit v1.2.3