#include #include #include #include #include #include #include #ifdef RPC_DEBUG # define RPCDBG_FACILITY RPCDBG_AUTH #endif static inline int gss_krb5_padding(int blocksize, int length) { /* Most of the code is block-size independent but currently we * use only 8: */ BUG_ON(blocksize != 8); return 8 - (length & 7); } static inline void gss_krb5_add_padding(struct xdr_buf *buf, int offset, int blocksize) { int padding = gss_krb5_padding(blocksize, buf->len - offset); char *p; struct kvec *iov; if (buf->page_len || buf->tail[0].iov_len) iov = &buf->tail[0]; else iov = &buf->head[0]; p = iov->iov_base + iov->iov_len; iov->iov_len += padding; buf->len += padding; memset(p, padding, padding); } static inline int gss_krb5_remove_padding(struct xdr_buf *buf, int blocksize) { u8 *ptr; u8 pad; size_t len = buf->len; if (len <= buf->head[0].iov_len) { pad = *(u8 *)(buf->head[0].iov_base + len - 1); if (pad > buf->head[0].iov_len) return -EINVAL; buf->head[0].iov_len -= pad; goto out; } else len -= buf->head[0].iov_len; if (len <= buf->page_len) { unsigned int last = (buf->page_base + len - 1) >>PAGE_CACHE_SHIFT; unsigned int offset = (buf->page_base + len - 1) & (PAGE_CACHE_SIZE - 1); ptr = kmap_atomic(buf->pages[last], KM_USER0); pad = *(ptr + offset); kunmap_atomic(ptr, KM_USER0); goto out; } else len -= buf->page_len; BUG_ON(len > buf->tail[0].iov_len); pad = *(u8 *)(buf->tail[0].iov_base + len - 1); out: /* XXX: NOTE: we do not adjust the page lengths--they represent * a range of data in the real filesystem page cache, and we need * to know that range so the xdr code can properly place read data. * However adjusting the head length, as we do above, is harmless. * In the case of a request that fits into a single page, the server * also uses length and head length together to determine the original * start of the request to copy the request for deferal; so it's * easier on the server if we adjust head and tail length in tandem. * It's not really a problem that we don't fool with the page and * tail lengths, though--at worst badly formed xdr might lead the * server to attempt to parse the padding. * XXX: Document all these weird requirements for gss mechanism * wrap/unwrap functions. */ if (pad > blocksize) return -EINVAL; if (buf->len > pad) buf->len -= pad; else return -EINVAL; return 0; } static inline void make_confounder(char *p, int blocksize) { static u64 i = 0; u64 *q = (u64 *)p; /* rfc1964 claims this should be "random". But all that's really * necessary is that it be unique. And not even that is necessary in * our case since our "gssapi" implementation exists only to support * rpcsec_gss, so we know that the only buffers we will ever encrypt * already begin with a unique sequence number. Just to hedge my bets * I'll make a half-hearted attempt at something unique, but ensuring * uniqueness would mean worrying about atomicity and rollover, and I * don't care enough. */ BUG_ON(blocksize != 8); *q = i++; } /* Assumptions: the head and tail of inbuf are ours to play with. * The pages, however, may be real pages in the page cache and we replace * them with scratch pages from **pages before writing to them. */ /* XXX: obviously the above should be documentation of wrap interface, * and shouldn't be in this kerberos-specific file. */ /* XXX factor out common code with seal/unseal. */ u32 gss_wrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf, struct page **pages) { struct krb5_ctx *kctx = ctx->internal_ctx_id; char cksumdata[16]; struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata}; int blocksize = 0, plainlen; unsigned char *ptr, *krb5_hdr, *msg_start; s32 now; int headlen; struct page **tmp_pages; u32 seq_send; dprintk("RPC: gss_wrap_kerberos\n"); now = get_seconds(); blocksize = crypto_blkcipher_blocksize(kctx->enc); gss_krb5_add_padding(buf, offset, blocksize); BUG_ON((buf->len - offset) % blocksize); plainlen = blocksize + buf->len - offset; headlen = g_token_size(&kctx->mech_used, 22 + plainlen) - (buf->len - offset); ptr = buf->head[0].iov_base + offset; /* shift data to make room for header. */ /* XXX Would be cleverer to encrypt while copying. */ /* XXX bounds checking, slack, etc. */ memmove(ptr + headlen, ptr, buf->head[0].iov_len - offset); buf->head[0].iov_len += headlen; buf->len += headlen; BUG_ON((buf->len - offset - headlen) % blocksize); g_make_token_header(&kctx->mech_used, 22 + plainlen, &ptr); *ptr++ = (unsigned char) ((KG_TOK_WRAP_MSG>>8)&0xff); *ptr++ = (unsigned char) (KG_TOK_WRAP_MSG&0xff); /* ptr now at byte 2 of header described in rfc 1964, section 1.2.1: */ krb5_hdr = ptr - 2; msg_start = krb5_hdr + 24; *(__be16 *)(krb5_hdr + 2) = htons(SGN_ALG_DES_MAC_MD5); memset(krb5_hdr + 4, 0xff, 4); *(__be16 *)(krb5_hdr + 4) = htons(SEAL_ALG_DES); make_confounder(msg_start, blocksize); /* XXXJBF: UGH!: */ tmp_pages = buf->pages; buf->pages = pages; if (make_checksum("md5", krb5_hdr, 8, buf, offset + headlen - blocksize, &md5cksum)) return GSS_S_FAILURE; buf->pages = tmp_pages; if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, md5cksum.data, md5cksum.len)) return GSS_S_FAILURE; memcpy(krb5_hdr + 16, md5cksum.data + md5cksum.len - 8, 8); spin_lock(&krb5_seq_lock); seq_send = kctx->seq_send++; spin_unlock(&krb5_seq_lock); /* XXX would probably be more efficient to compute checksum * and encrypt at the same time: */ if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff, seq_send, krb5_hdr + 16, krb5_hdr + 8))) return GSS_S_FAILURE; if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize, pages)) return GSS_S_FAILURE; return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; } u32 gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf) { struct krb5_ctx *kctx = ctx->internal_ctx_id; int signalg; int sealalg; char cksumdata[16]; struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata}; s32 now; int direction; s32 seqnum; unsigned char *ptr; int bodysize; void *data_start, *orig_start; int data_len; int blocksize; dprintk("RPC: gss_unwrap_kerberos\n"); ptr = (u8 *)buf->head[0].iov_base + offset; if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr, buf->len - offset)) return GSS_S_DEFECTIVE_TOKEN; if ((*ptr++ != ((KG_TOK_WRAP_MSG>>8)&0xff)) || (*ptr++ != (KG_TOK_WRAP_MSG &0xff)) ) return GSS_S_DEFECTIVE_TOKEN; /* XXX sanity-check bodysize?? */ /* get the sign and seal algorithms */ signalg = ptr[0] + (ptr[1] << 8); if (signalg != SGN_ALG_DES_MAC_MD5) return GSS_S_DEFECTIVE_TOKEN; sealalg = ptr[2] + (ptr[3] << 8); if (sealalg != SEAL_ALG_DES) return GSS_S_DEFECTIVE_TOKEN; if ((ptr[4] != 0xff) || (ptr[5] != 0xff)) return GSS_S_DEFECTIVE_TOKEN; if (gss_decrypt_xdr_buf(kctx->enc, buf, ptr + 22 - (unsigned char *)buf->head[0].iov_base)) return GSS_S_DEFECTIVE_TOKEN; if (make_checksum("md5", ptr - 2, 8, buf, ptr + 22 - (unsigned char *)buf->head[0].iov_base, &md5cksum)) return GSS_S_FAILURE; if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, md5cksum.data, md5cksum.len)) return GSS_S_FAILURE; if (memcmp(md5cksum.data + 8, ptr + 14, 8)) return GSS_S_BAD_SIG; /* it got through unscathed. Make sure the context is unexpired */ now = get_seconds(); if (now > kctx->endtime) return GSS_S_CONTEXT_EXPIRED; /* do sequencing checks */ if (krb5_get_seq_num(kctx->seq, ptr + 14, ptr + 6, &direction, &seqnum)) return GSS_S_BAD_SIG; if ((kctx->initiate && direction != 0xff) || (!kctx->initiate && direction != 0)) return GSS_S_BAD_SIG; /* Copy the data back to the right position. XXX: Would probably be * better to copy and encrypt at the same time. */ blocksize = crypto_blkcipher_blocksize(kctx->enc); data_start = ptr + 22 + blocksize; orig_start = buf->head[0].iov_base + offset; data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start; memmove(orig_start, data_start, data_len); buf->head[0].iov_len -= (data_start - orig_start); buf->len -= (data_start - orig_start); if (gss_krb5_remove_padding(buf, blocksize)) return GSS_S_DEFECTIVE_TOKEN; return GSS_S_COMPLETE; }