/* * COPYRIGHT (c) 2008 * The Regents of the University of Michigan * ALL RIGHTS RESERVED * * Permission is granted to use, copy, create derivative works * and redistribute this software and such derivative works * for any purpose, so long as the name of The University of * Michigan is not used in any advertising or publicity * pertaining to the use of distribution of this software * without specific, written prior authorization. If the * above copyright notice or any other identification of the * University of Michigan is included in any copy of any * portion of this software, then the disclaimer below must * also be included. * * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION * FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY * PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF * MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING * WITHOUT LIMITATION THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE * REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE * FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR * CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING * OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF * SUCH DAMAGES. */ #include #include #include #include #include #include #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) # define RPCDBG_FACILITY RPCDBG_AUTH #endif static inline int gss_krb5_padding(int blocksize, int length) { return blocksize - (length % blocksize); } 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_SHIFT; unsigned int offset = (buf->page_base + len - 1) & (PAGE_SIZE - 1); ptr = kmap_atomic(buf->pages[last]); pad = *(ptr + offset); kunmap_atomic(ptr); 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; } void gss_krb5_make_confounder(char *p, u32 conflen) { 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. */ /* initialize to random value */ if (i == 0) { i = prandom_u32(); i = (i << 32) | prandom_u32(); } switch (conflen) { case 16: *q++ = i++; fallthrough; case 8: *q++ = i++; break; default: BUG(); } } /* 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. */ static u32 gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf, struct page **pages) { char cksumdata[GSS_KRB5_MAX_CKSUM_LEN]; struct xdr_netobj md5cksum = {.len = sizeof(cksumdata), .data = cksumdata}; int blocksize = 0, plainlen; unsigned char *ptr, *msg_start; time64_t now; int headlen; struct page **tmp_pages; u32 seq_send; u8 *cksumkey; u32 conflen = kctx->gk5e->conflen; dprintk("RPC: %s\n", __func__); now = ktime_get_real_seconds(); blocksize = crypto_sync_skcipher_blocksize(kctx->enc); gss_krb5_add_padding(buf, offset, blocksize); BUG_ON((buf->len - offset) % blocksize); plainlen = conflen + buf->len - offset; headlen = g_token_size(&kctx->mech_used, GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength + plainlen) - (buf->len - offset); ptr = buf->head[0].iov_base + offset; /* shift data to make room for header. */ xdr_extend_head(buf, offset, headlen); /* XXX Would be cleverer to encrypt while copying. */ BUG_ON((buf->len - offset - headlen) % blocksize); g_make_token_header(&kctx->mech_used, GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength + plainlen, &ptr); /* ptr now at header described in rfc 1964, section 1.2.1: */ ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff); ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff); msg_start = ptr + GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength; /* * signalg and sealalg are stored as if they were converted from LE * to host endian, even though they're opaque pairs of bytes according * to the RFC. */ *(__le16 *)(ptr + 2) = cpu_to_le16(kctx->gk5e->signalg); *(__le16 *)(ptr + 4) = cpu_to_le16(kctx->gk5e->sealalg); ptr[6] = 0xff; ptr[7] = 0xff; gss_krb5_make_confounder(msg_start, conflen); if (kctx->gk5e->keyed_cksum) cksumkey = kctx->cksum; else cksumkey = NULL; /* XXXJBF: UGH!: */ tmp_pages = buf->pages; buf->pages = pages; if (make_checksum(kctx, ptr, 8, buf, offset + headlen - conflen, cksumkey, KG_USAGE_SEAL, &md5cksum)) return GSS_S_FAILURE; buf->pages = tmp_pages; memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len); seq_send = atomic_fetch_inc(&kctx->seq_send); /* XXX would probably be more efficient to compute checksum * and encrypt at the same time: */ if ((krb5_make_seq_num(kctx, kctx->seq, kctx->initiate ? 0 : 0xff, seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8))) return GSS_S_FAILURE; if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - conflen, pages)) return GSS_S_FAILURE; return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; } static u32 gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, int len, struct xdr_buf *buf, unsigned int *slack, unsigned int *align) { int signalg; int sealalg; char cksumdata[GSS_KRB5_MAX_CKSUM_LEN]; struct xdr_netobj md5cksum = {.len = sizeof(cksumdata), .data = cksumdata}; time64_t now; int direction; s32 seqnum; unsigned char *ptr; int bodysize; void *data_start, *orig_start; int data_len; int blocksize; u32 conflen = kctx->gk5e->conflen; int crypt_offset; u8 *cksumkey; unsigned int saved_len = buf->len; dprintk("RPC: gss_unwrap_kerberos\n"); ptr = (u8 *)buf->head[0].iov_base + offset; if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr, len - offset)) return GSS_S_DEFECTIVE_TOKEN; if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) || (ptr[1] != (KG_TOK_WRAP_MSG & 0xff))) return GSS_S_DEFECTIVE_TOKEN; /* XXX sanity-check bodysize?? */ /* get the sign and seal algorithms */ signalg = ptr[2] + (ptr[3] << 8); if (signalg != kctx->gk5e->signalg) return GSS_S_DEFECTIVE_TOKEN; sealalg = ptr[4] + (ptr[5] << 8); if (sealalg != kctx->gk5e->sealalg) return GSS_S_DEFECTIVE_TOKEN; if ((ptr[6] != 0xff) || (ptr[7] != 0xff)) return GSS_S_DEFECTIVE_TOKEN; /* * Data starts after token header and checksum. ptr points * to the beginning of the token header */ crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) - (unsigned char *)buf->head[0].iov_base; buf->len = len; if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset)) return GSS_S_DEFECTIVE_TOKEN; if (kctx->gk5e->keyed_cksum) cksumkey = kctx->cksum; else cksumkey = NULL; if (make_checksum(kctx, ptr, 8, buf, crypt_offset, cksumkey, KG_USAGE_SEAL, &md5cksum)) return GSS_S_FAILURE; if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN, kctx->gk5e->cksumlength)) return GSS_S_BAD_SIG; /* it got through unscathed. Make sure the context is unexpired */ now = ktime_get_real_seconds(); if (now > kctx->endtime) return GSS_S_CONTEXT_EXPIRED; /* do sequencing checks */ if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8, &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_sync_skcipher_blocksize(kctx->enc); data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) + conflen; 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 = len - (data_start - orig_start); if (gss_krb5_remove_padding(buf, blocksize)) return GSS_S_DEFECTIVE_TOKEN; /* slack must include room for krb5 padding */ *slack = XDR_QUADLEN(saved_len - buf->len); /* The GSS blob always precedes the RPC message payload */ *align = *slack; return GSS_S_COMPLETE; } /* * We can shift data by up to LOCAL_BUF_LEN bytes in a pass. If we need * to do more than that, we shift repeatedly. Kevin Coffman reports * seeing 28 bytes as the value used by Microsoft clients and servers * with AES, so this constant is chosen to allow handling 28 in one pass * without using too much stack space. * * If that proves to a problem perhaps we could use a more clever * algorithm. */ #define LOCAL_BUF_LEN 32u static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift) { char head[LOCAL_BUF_LEN]; char tmp[LOCAL_BUF_LEN]; unsigned int this_len, i; BUG_ON(shift > LOCAL_BUF_LEN); read_bytes_from_xdr_buf(buf, 0, head, shift); for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) { this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift)); read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len); write_bytes_to_xdr_buf(buf, i, tmp, this_len); } write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift); } static void _rotate_left(struct xdr_buf *buf, unsigned int shift) { int shifted = 0; int this_shift; shift %= buf->len; while (shifted < shift) { this_shift = min(shift - shifted, LOCAL_BUF_LEN); rotate_buf_a_little(buf, this_shift); shifted += this_shift; } } static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift) { struct xdr_buf subbuf; xdr_buf_subsegment(buf, &subbuf, base, buf->len - base); _rotate_left(&subbuf, shift); } static u32 gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf, struct page **pages) { u8 *ptr; time64_t now; u8 flags = 0x00; __be16 *be16ptr; __be64 *be64ptr; u32 err; dprintk("RPC: %s\n", __func__); if (kctx->gk5e->encrypt_v2 == NULL) return GSS_S_FAILURE; /* make room for gss token header */ if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN)) return GSS_S_FAILURE; /* construct gss token header */ ptr = buf->head[0].iov_base + offset; *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff); *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff); if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0) flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR; if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0) flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY; /* We always do confidentiality in wrap tokens */ flags |= KG2_TOKEN_FLAG_SEALED; *ptr++ = flags; *ptr++ = 0xff; be16ptr = (__be16 *)ptr; *be16ptr++ = 0; /* "inner" token header always uses 0 for RRC */ *be16ptr++ = 0; be64ptr = (__be64 *)be16ptr; *be64ptr = cpu_to_be64(atomic64_fetch_inc(&kctx->seq_send64)); err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, pages); if (err) return err; now = ktime_get_real_seconds(); return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; } static u32 gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len, struct xdr_buf *buf, unsigned int *slack, unsigned int *align) { time64_t now; u8 *ptr; u8 flags = 0x00; u16 ec, rrc; int err; u32 headskip, tailskip; u8 decrypted_hdr[GSS_KRB5_TOK_HDR_LEN]; unsigned int movelen; dprintk("RPC: %s\n", __func__); if (kctx->gk5e->decrypt_v2 == NULL) return GSS_S_FAILURE; ptr = buf->head[0].iov_base + offset; if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP) return GSS_S_DEFECTIVE_TOKEN; flags = ptr[2]; if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) || (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR))) return GSS_S_BAD_SIG; if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) { dprintk("%s: token missing expected sealed flag\n", __func__); return GSS_S_DEFECTIVE_TOKEN; } if (ptr[3] != 0xff) return GSS_S_DEFECTIVE_TOKEN; ec = be16_to_cpup((__be16 *)(ptr + 4)); rrc = be16_to_cpup((__be16 *)(ptr + 6)); /* * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss * doesn't want it checked; see page 6 of rfc 2203. */ if (rrc != 0) rotate_left(offset + 16, buf, rrc); err = (*kctx->gk5e->decrypt_v2)(kctx, offset, len, buf, &headskip, &tailskip); if (err) return GSS_S_FAILURE; /* * Retrieve the decrypted gss token header and verify * it against the original */ err = read_bytes_from_xdr_buf(buf, len - GSS_KRB5_TOK_HDR_LEN - tailskip, decrypted_hdr, GSS_KRB5_TOK_HDR_LEN); if (err) { dprintk("%s: error %u getting decrypted_hdr\n", __func__, err); return GSS_S_FAILURE; } if (memcmp(ptr, decrypted_hdr, 6) || memcmp(ptr + 8, decrypted_hdr + 8, 8)) { dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__); return GSS_S_FAILURE; } /* do sequencing checks */ /* it got through unscathed. Make sure the context is unexpired */ now = ktime_get_real_seconds(); if (now > kctx->endtime) return GSS_S_CONTEXT_EXPIRED; /* * Move the head data back to the right position in xdr_buf. * We ignore any "ec" data since it might be in the head or * the tail, and we really don't need to deal with it. * Note that buf->head[0].iov_len may indicate the available * head buffer space rather than that actually occupied. */ movelen = min_t(unsigned int, buf->head[0].iov_len, len); movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip; BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen > buf->head[0].iov_len); memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen); buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip; buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip); /* Trim off the trailing "extra count" and checksum blob */ xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip); *align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip); *slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip); return GSS_S_COMPLETE; } u32 gss_wrap_kerberos(struct gss_ctx *gctx, int offset, struct xdr_buf *buf, struct page **pages) { struct krb5_ctx *kctx = gctx->internal_ctx_id; switch (kctx->enctype) { default: BUG(); case ENCTYPE_DES_CBC_RAW: case ENCTYPE_DES3_CBC_RAW: return gss_wrap_kerberos_v1(kctx, offset, buf, pages); case ENCTYPE_AES128_CTS_HMAC_SHA1_96: case ENCTYPE_AES256_CTS_HMAC_SHA1_96: return gss_wrap_kerberos_v2(kctx, offset, buf, pages); } } u32 gss_unwrap_kerberos(struct gss_ctx *gctx, int offset, int len, struct xdr_buf *buf) { struct krb5_ctx *kctx = gctx->internal_ctx_id; switch (kctx->enctype) { default: BUG(); case ENCTYPE_DES_CBC_RAW: case ENCTYPE_DES3_CBC_RAW: return gss_unwrap_kerberos_v1(kctx, offset, len, buf, &gctx->slack, &gctx->align); case ENCTYPE_AES128_CTS_HMAC_SHA1_96: case ENCTYPE_AES256_CTS_HMAC_SHA1_96: return gss_unwrap_kerberos_v2(kctx, offset, len, buf, &gctx->slack, &gctx->align); } }