Author: J. Bruce Fields Date: Thu, 13 Oct 2005 16:55:13 -0400 RPCSEC_GSS: Add support for privacy to krb5 rpcsec_gss mechanism. Add support for privacy to the krb5 rpcsec_gss mechanism. Signed-off-by: J. Bruce Fields Signed-off-by: Trond Myklebust --- include/linux/sunrpc/gss_krb5.h | 18 + net/sunrpc/auth_gss/Makefile | 2 net/sunrpc/auth_gss/gss_krb5_crypto.c | 156 ++++++++++++++ net/sunrpc/auth_gss/gss_krb5_mech.c | 7 net/sunrpc/auth_gss/gss_krb5_seal.c | 4 net/sunrpc/auth_gss/gss_krb5_unseal.c | 2 net/sunrpc/auth_gss/gss_krb5_wrap.c | 370 ++++++++++++++++++++++++++++++++++ 7 files changed, 552 insertions(+), 7 deletions(-) Index: linux-2.6/include/linux/sunrpc/gss_krb5.h =================================================================== --- linux-2.6.orig/include/linux/sunrpc/gss_krb5.h +++ linux-2.6/include/linux/sunrpc/gss_krb5.h @@ -116,7 +116,7 @@ enum seal_alg { s32 make_checksum(s32 cksumtype, char *header, int hdrlen, struct xdr_buf *body, - struct xdr_netobj *cksum); + int body_offset, struct xdr_netobj *cksum); u32 krb5_make_token(struct krb5_ctx *context_handle, int qop_req, @@ -129,6 +129,15 @@ krb5_read_token(struct krb5_ctx *context struct xdr_buf *message_buffer, int *qop_state); u32 +gss_wrap_kerberos(struct gss_ctx *ctx_id, u32 qop, int offset, + struct xdr_buf *outbuf, struct page **pages); + +u32 +gss_unwrap_kerberos(struct gss_ctx *ctx_id, u32 *qop, int offset, + struct xdr_buf *buf); + + +u32 krb5_encrypt(struct crypto_tfm * key, void *iv, void *in, void *out, int length); @@ -136,6 +145,13 @@ u32 krb5_decrypt(struct crypto_tfm * key, void *iv, void *in, void *out, int length); +int +gss_encrypt_xdr_buf(struct crypto_tfm *tfm, struct xdr_buf *outbuf, int offset, + struct page **pages); + +int +gss_decrypt_xdr_buf(struct crypto_tfm *tfm, struct xdr_buf *inbuf, int offset); + s32 krb5_make_seq_num(struct crypto_tfm * key, int direction, Index: linux-2.6/net/sunrpc/auth_gss/gss_krb5_crypto.c =================================================================== --- linux-2.6.orig/net/sunrpc/auth_gss/gss_krb5_crypto.c +++ linux-2.6/net/sunrpc/auth_gss/gss_krb5_crypto.c @@ -218,7 +218,7 @@ checksummer(struct scatterlist *sg, void /* checksum the plaintext data and hdrlen bytes of the token header */ s32 make_checksum(s32 cksumtype, char *header, int hdrlen, struct xdr_buf *body, - struct xdr_netobj *cksum) + int body_offset, struct xdr_netobj *cksum) { char *cksumname; struct crypto_tfm *tfm = NULL; /* XXX add to ctx? */ @@ -243,7 +243,8 @@ make_checksum(s32 cksumtype, char *heade crypto_digest_init(tfm); buf_to_sg(sg, header, hdrlen); crypto_digest_update(tfm, sg, 1); - process_xdr_buf(body, 0, body->len, checksummer, tfm); + process_xdr_buf(body, body_offset, body->len - body_offset, + checksummer, tfm); crypto_digest_final(tfm, cksum->data); code = 0; out: @@ -252,3 +253,154 @@ out: } EXPORT_SYMBOL(make_checksum); + +struct encryptor_desc { + u8 iv[8]; /* XXX hard-coded blocksize */ + struct crypto_tfm *tfm; + int pos; + struct xdr_buf *outbuf; + struct page **pages; + struct scatterlist infrags[4]; + struct scatterlist outfrags[4]; + int fragno; + int fraglen; +}; + +static int +encryptor(struct scatterlist *sg, void *data) +{ + struct encryptor_desc *desc = data; + struct xdr_buf *outbuf = desc->outbuf; + struct page *in_page; + int thislen = desc->fraglen + sg->length; + int fraglen, ret; + int page_pos; + + /* Worst case is 4 fragments: head, end of page 1, start + * of page 2, tail. Anything more is a bug. */ + BUG_ON(desc->fragno > 3); + desc->infrags[desc->fragno] = *sg; + desc->outfrags[desc->fragno] = *sg; + + page_pos = desc->pos - outbuf->head[0].iov_len; + if (page_pos >= 0 && page_pos < outbuf->page_len) { + /* pages are not in place: */ + int i = (page_pos + outbuf->page_base) >> PAGE_CACHE_SHIFT; + in_page = desc->pages[i]; + } else { + in_page = sg->page; + } + desc->infrags[desc->fragno].page = in_page; + desc->fragno++; + desc->fraglen += sg->length; + desc->pos += sg->length; + + fraglen = thislen & 7; /* XXX hardcoded blocksize */ + thislen -= fraglen; + + if (thislen == 0) + return 0; + + ret = crypto_cipher_encrypt_iv(desc->tfm, desc->outfrags, desc->infrags, + thislen, desc->iv); + if (ret) + return ret; + if (fraglen) { + desc->outfrags[0].page = sg->page; + desc->outfrags[0].offset = sg->offset + sg->length - fraglen; + desc->outfrags[0].length = fraglen; + desc->infrags[0] = desc->outfrags[0]; + desc->infrags[0].page = in_page; + desc->fragno = 1; + desc->fraglen = fraglen; + } else { + desc->fragno = 0; + desc->fraglen = 0; + } + return 0; +} + +int +gss_encrypt_xdr_buf(struct crypto_tfm *tfm, struct xdr_buf *buf, int offset, + struct page **pages) +{ + int ret; + struct encryptor_desc desc; + + BUG_ON((buf->len - offset) % crypto_tfm_alg_blocksize(tfm) != 0); + + memset(desc.iv, 0, sizeof(desc.iv)); + desc.tfm = tfm; + desc.pos = offset; + desc.outbuf = buf; + desc.pages = pages; + desc.fragno = 0; + desc.fraglen = 0; + + ret = process_xdr_buf(buf, offset, buf->len - offset, encryptor, &desc); + return ret; +} + +EXPORT_SYMBOL(gss_encrypt_xdr_buf); + +struct decryptor_desc { + u8 iv[8]; /* XXX hard-coded blocksize */ + struct crypto_tfm *tfm; + struct scatterlist frags[4]; + int fragno; + int fraglen; +}; + +static int +decryptor(struct scatterlist *sg, void *data) +{ + struct decryptor_desc *desc = data; + int thislen = desc->fraglen + sg->length; + int fraglen, ret; + + /* Worst case is 4 fragments: head, end of page 1, start + * of page 2, tail. Anything more is a bug. */ + BUG_ON(desc->fragno > 3); + desc->frags[desc->fragno] = *sg; + desc->fragno++; + desc->fraglen += sg->length; + + fraglen = thislen & 7; /* XXX hardcoded blocksize */ + thislen -= fraglen; + + if (thislen == 0) + return 0; + + ret = crypto_cipher_decrypt_iv(desc->tfm, desc->frags, desc->frags, + thislen, desc->iv); + if (ret) + return ret; + if (fraglen) { + desc->frags[0].page = sg->page; + desc->frags[0].offset = sg->offset + sg->length - fraglen; + desc->frags[0].length = fraglen; + desc->fragno = 1; + desc->fraglen = fraglen; + } else { + desc->fragno = 0; + desc->fraglen = 0; + } + return 0; +} + +int +gss_decrypt_xdr_buf(struct crypto_tfm *tfm, struct xdr_buf *buf, int offset) +{ + struct decryptor_desc desc; + + /* XXXJBF: */ + BUG_ON((buf->len - offset) % crypto_tfm_alg_blocksize(tfm) != 0); + + memset(desc.iv, 0, sizeof(desc.iv)); + desc.tfm = tfm; + desc.fragno = 0; + desc.fraglen = 0; + return process_xdr_buf(buf, offset, buf->len - offset, decryptor, &desc); +} + +EXPORT_SYMBOL(gss_decrypt_xdr_buf); Index: linux-2.6/net/sunrpc/auth_gss/gss_krb5_mech.c =================================================================== --- linux-2.6.orig/net/sunrpc/auth_gss/gss_krb5_mech.c +++ linux-2.6/net/sunrpc/auth_gss/gss_krb5_mech.c @@ -226,6 +226,8 @@ static struct gss_api_ops gss_kerberos_o .gss_import_sec_context = gss_import_sec_context_kerberos, .gss_get_mic = gss_get_mic_kerberos, .gss_verify_mic = gss_verify_mic_kerberos, + .gss_wrap = gss_wrap_kerberos, + .gss_unwrap = gss_unwrap_kerberos, .gss_delete_sec_context = gss_delete_sec_context_kerberos, }; @@ -240,6 +242,11 @@ static struct pf_desc gss_kerberos_pfs[] .service = RPC_GSS_SVC_INTEGRITY, .name = "krb5i", }, + [2] = { + .pseudoflavor = RPC_AUTH_GSS_KRB5P, + .service = RPC_GSS_SVC_PRIVACY, + .name = "krb5p", + }, }; static struct gss_api_mech gss_kerberos_mech = { Index: linux-2.6/net/sunrpc/auth_gss/gss_krb5_seal.c =================================================================== --- linux-2.6.orig/net/sunrpc/auth_gss/gss_krb5_seal.c +++ linux-2.6/net/sunrpc/auth_gss/gss_krb5_seal.c @@ -116,8 +116,8 @@ krb5_make_token(struct krb5_ctx *ctx, in *(u16 *)(krb5_hdr + 2) = htons(ctx->signalg); memset(krb5_hdr + 4, 0xff, 4); - if (make_checksum(checksum_type, krb5_hdr, 8, text, &md5cksum)) - goto out_err; + if (make_checksum(checksum_type, krb5_hdr, 8, text, 0, &md5cksum)) + goto out_err; switch (ctx->signalg) { case SGN_ALG_DES_MAC_MD5: Index: linux-2.6/net/sunrpc/auth_gss/gss_krb5_unseal.c =================================================================== --- linux-2.6.orig/net/sunrpc/auth_gss/gss_krb5_unseal.c +++ linux-2.6/net/sunrpc/auth_gss/gss_krb5_unseal.c @@ -136,7 +136,7 @@ krb5_read_token(struct krb5_ctx *ctx, switch (signalg) { case SGN_ALG_DES_MAC_MD5: ret = make_checksum(checksum_type, ptr - 2, 8, - message_buffer, &md5cksum); + message_buffer, 0, &md5cksum); if (ret) goto out; Index: linux-2.6/net/sunrpc/auth_gss/gss_krb5_wrap.c =================================================================== --- /dev/null +++ linux-2.6/net/sunrpc/auth_gss/gss_krb5_wrap.c @@ -0,0 +1,370 @@ +#include +#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; + int 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) { + int last = (buf->page_base + len - 1) + >>PAGE_CACHE_SHIFT; + int offset = (buf->page_base + len - 1) + & (PAGE_CACHE_SIZE - 1); + ptr = kmap_atomic(buf->pages[last], KM_SKB_SUNRPC_DATA); + pad = *(ptr + offset); + kunmap_atomic(ptr, KM_SKB_SUNRPC_DATA); + 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, u32 qop, int offset, + struct xdr_buf *buf, struct page **pages) +{ + struct krb5_ctx *kctx = ctx->internal_ctx_id; + s32 checksum_type; + struct xdr_netobj md5cksum = {.len = 0, .data = NULL}; + int blocksize = 0, plainlen; + unsigned char *ptr, *krb5_hdr, *msg_start; + s32 now; + int headlen; + struct page **tmp_pages; + + dprintk("RPC: gss_wrap_kerberos\n"); + + now = get_seconds(); + + if (qop != 0) + goto out_err; + + switch (kctx->signalg) { + case SGN_ALG_DES_MAC_MD5: + checksum_type = CKSUMTYPE_RSA_MD5; + break; + default: + dprintk("RPC: gss_krb5_seal: kctx->signalg %d not" + " supported\n", kctx->signalg); + goto out_err; + } + if (kctx->sealalg != SEAL_ALG_NONE && kctx->sealalg != SEAL_ALG_DES) { + dprintk("RPC: gss_krb5_seal: kctx->sealalg %d not supported\n", + kctx->sealalg); + goto out_err; + } + + blocksize = crypto_tfm_alg_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; + /* XXXJBF: */ BUG_ON(buf->head[0].iov_base + offset + headlen != msg_start + blocksize); + + *(u16 *)(krb5_hdr + 2) = htons(kctx->signalg); + memset(krb5_hdr + 4, 0xff, 4); + *(u16 *)(krb5_hdr + 4) = htons(kctx->sealalg); + + make_confounder(msg_start, blocksize); + + /* XXXJBF: UGH!: */ + tmp_pages = buf->pages; + buf->pages = pages; + if (make_checksum(checksum_type, krb5_hdr, 8, buf, + offset + headlen - blocksize, &md5cksum)) + goto out_err; + buf->pages = tmp_pages; + + switch (kctx->signalg) { + case SGN_ALG_DES_MAC_MD5: + if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, + md5cksum.data, md5cksum.len)) + goto out_err; + memcpy(krb5_hdr + 16, + md5cksum.data + md5cksum.len - KRB5_CKSUM_LENGTH, + KRB5_CKSUM_LENGTH); + + dprintk("RPC: make_seal_token: cksum data: \n"); + print_hexl((u32 *) (krb5_hdr + 16), KRB5_CKSUM_LENGTH, 0); + break; + default: + BUG(); + } + + kfree(md5cksum.data); + + /* 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, + kctx->seq_send, krb5_hdr + 16, krb5_hdr + 8))) + goto out_err; + + if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize, + pages)) + goto out_err; + + kctx->seq_send++; + + return ((kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE); +out_err: + if (md5cksum.data) kfree(md5cksum.data); + return GSS_S_FAILURE; +} + +u32 +gss_unwrap_kerberos(struct gss_ctx *ctx, u32 *qop, int offset, + struct xdr_buf *buf) +{ + struct krb5_ctx *kctx = ctx->internal_ctx_id; + int signalg; + int sealalg; + s32 checksum_type; + struct xdr_netobj md5cksum = {.len = 0, .data = NULL}; + s32 now; + int direction; + s32 seqnum; + unsigned char *ptr; + int bodysize; + u32 ret = GSS_S_DEFECTIVE_TOKEN; + 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)) + goto out; + + if ((*ptr++ != ((KG_TOK_WRAP_MSG>>8)&0xff)) || + (*ptr++ != (KG_TOK_WRAP_MSG &0xff)) ) + goto out; + + /* XXX sanity-check bodysize?? */ + + /* get the sign and seal algorithms */ + + signalg = ptr[0] + (ptr[1] << 8); + sealalg = ptr[2] + (ptr[3] << 8); + + /* Sanity checks */ + + if ((ptr[4] != 0xff) || (ptr[5] != 0xff)) + goto out; + + if (sealalg == 0xffff) + goto out; + + /* in the current spec, there is only one valid seal algorithm per + key type, so a simple comparison is ok */ + + if (sealalg != kctx->sealalg) + goto out; + + /* there are several mappings of seal algorithms to sign algorithms, + but few enough that we can try them all. */ + + if ((kctx->sealalg == SEAL_ALG_NONE && signalg > 1) || + (kctx->sealalg == SEAL_ALG_1 && signalg != SGN_ALG_3) || + (kctx->sealalg == SEAL_ALG_DES3KD && + signalg != SGN_ALG_HMAC_SHA1_DES3_KD)) + goto out; + + if (gss_decrypt_xdr_buf(kctx->enc, buf, + ptr + 22 - (unsigned char *)buf->head[0].iov_base)) + goto out; + + /* compute the checksum of the message */ + + /* initialize the the cksum */ + switch (signalg) { + case SGN_ALG_DES_MAC_MD5: + checksum_type = CKSUMTYPE_RSA_MD5; + break; + default: + ret = GSS_S_DEFECTIVE_TOKEN; + goto out; + } + + switch (signalg) { + case SGN_ALG_DES_MAC_MD5: + ret = make_checksum(checksum_type, ptr - 2, 8, buf, + ptr + 22 - (unsigned char *)buf->head[0].iov_base, &md5cksum); + if (ret) + goto out; + + ret = krb5_encrypt(kctx->seq, NULL, md5cksum.data, + md5cksum.data, md5cksum.len); + if (ret) + goto out; + + if (memcmp(md5cksum.data + 8, ptr + 14, 8)) { + ret = GSS_S_BAD_SIG; + goto out; + } + break; + default: + ret = GSS_S_DEFECTIVE_TOKEN; + goto out; + } + + /* it got through unscathed. Make sure the context is unexpired */ + + if (qop) + *qop = GSS_C_QOP_DEFAULT; + + now = get_seconds(); + + ret = GSS_S_CONTEXT_EXPIRED; + if (now > kctx->endtime) + goto out; + + /* do sequencing checks */ + + ret = GSS_S_BAD_SIG; + if ((ret = krb5_get_seq_num(kctx->seq, ptr + 14, ptr + 6, &direction, + &seqnum))) + goto out; + + if ((kctx->initiate && direction != 0xff) || + (!kctx->initiate && direction != 0)) + goto out; + + /* Copy the data back to the right position. XXX: Would probably be + * better to copy and encrypt at the same time. */ + + blocksize = crypto_tfm_alg_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); + + ret = GSS_S_DEFECTIVE_TOKEN; + if (gss_krb5_remove_padding(buf, blocksize)) + goto out; + + ret = GSS_S_COMPLETE; +out: + if (md5cksum.data) kfree(md5cksum.data); + return ret; +} Index: linux-2.6/net/sunrpc/auth_gss/Makefile =================================================================== --- linux-2.6.orig/net/sunrpc/auth_gss/Makefile +++ linux-2.6/net/sunrpc/auth_gss/Makefile @@ -10,7 +10,7 @@ auth_rpcgss-objs := auth_gss.o gss_gener obj-$(CONFIG_RPCSEC_GSS_KRB5) += rpcsec_gss_krb5.o rpcsec_gss_krb5-objs := gss_krb5_mech.o gss_krb5_seal.o gss_krb5_unseal.o \ - gss_krb5_seqnum.o + gss_krb5_seqnum.o gss_krb5_wrap.o obj-$(CONFIG_RPCSEC_GSS_SPKM3) += rpcsec_gss_spkm3.o