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 <bfields@citi.umich.edu> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
J. Bruce Fields
committed by
Trond Myklebust
Trond Myklebust
parent
bfa91516b5
commit
14ae162c24
370
net/sunrpc/auth_gss/gss_krb5_wrap.c
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370
net/sunrpc/auth_gss/gss_krb5_wrap.c
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@@ -0,0 +1,370 @@
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/jiffies.h>
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#include <linux/sunrpc/gss_krb5.h>
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#include <linux/random.h>
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#include <linux/pagemap.h>
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#include <asm/scatterlist.h>
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#include <linux/crypto.h>
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#ifdef RPC_DEBUG
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# define RPCDBG_FACILITY RPCDBG_AUTH
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#endif
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static inline int
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gss_krb5_padding(int blocksize, int length)
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{
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/* Most of the code is block-size independent but currently we
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* use only 8: */
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BUG_ON(blocksize != 8);
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return 8 - (length & 7);
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}
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static inline void
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gss_krb5_add_padding(struct xdr_buf *buf, int offset, int blocksize)
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{
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int padding = gss_krb5_padding(blocksize, buf->len - offset);
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char *p;
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struct kvec *iov;
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if (buf->page_len || buf->tail[0].iov_len)
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iov = &buf->tail[0];
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else
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iov = &buf->head[0];
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p = iov->iov_base + iov->iov_len;
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iov->iov_len += padding;
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buf->len += padding;
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memset(p, padding, padding);
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}
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static inline int
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gss_krb5_remove_padding(struct xdr_buf *buf, int blocksize)
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{
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u8 *ptr;
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u8 pad;
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int len = buf->len;
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if (len <= buf->head[0].iov_len) {
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pad = *(u8 *)(buf->head[0].iov_base + len - 1);
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if (pad > buf->head[0].iov_len)
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return -EINVAL;
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buf->head[0].iov_len -= pad;
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goto out;
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} else
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len -= buf->head[0].iov_len;
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if (len <= buf->page_len) {
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int last = (buf->page_base + len - 1)
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>>PAGE_CACHE_SHIFT;
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int offset = (buf->page_base + len - 1)
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& (PAGE_CACHE_SIZE - 1);
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ptr = kmap_atomic(buf->pages[last], KM_SKB_SUNRPC_DATA);
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pad = *(ptr + offset);
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kunmap_atomic(ptr, KM_SKB_SUNRPC_DATA);
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goto out;
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} else
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len -= buf->page_len;
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BUG_ON(len > buf->tail[0].iov_len);
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pad = *(u8 *)(buf->tail[0].iov_base + len - 1);
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out:
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/* XXX: NOTE: we do not adjust the page lengths--they represent
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* a range of data in the real filesystem page cache, and we need
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* to know that range so the xdr code can properly place read data.
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* However adjusting the head length, as we do above, is harmless.
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* In the case of a request that fits into a single page, the server
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* also uses length and head length together to determine the original
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* start of the request to copy the request for deferal; so it's
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* easier on the server if we adjust head and tail length in tandem.
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* It's not really a problem that we don't fool with the page and
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* tail lengths, though--at worst badly formed xdr might lead the
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* server to attempt to parse the padding.
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* XXX: Document all these weird requirements for gss mechanism
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* wrap/unwrap functions. */
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if (pad > blocksize)
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return -EINVAL;
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if (buf->len > pad)
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buf->len -= pad;
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else
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return -EINVAL;
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return 0;
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}
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static inline void
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make_confounder(char *p, int blocksize)
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{
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static u64 i = 0;
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u64 *q = (u64 *)p;
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/* rfc1964 claims this should be "random". But all that's really
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* necessary is that it be unique. And not even that is necessary in
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* our case since our "gssapi" implementation exists only to support
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* rpcsec_gss, so we know that the only buffers we will ever encrypt
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* already begin with a unique sequence number. Just to hedge my bets
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* I'll make a half-hearted attempt at something unique, but ensuring
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* uniqueness would mean worrying about atomicity and rollover, and I
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* don't care enough. */
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BUG_ON(blocksize != 8);
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*q = i++;
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}
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/* Assumptions: the head and tail of inbuf are ours to play with.
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* The pages, however, may be real pages in the page cache and we replace
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* them with scratch pages from **pages before writing to them. */
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/* XXX: obviously the above should be documentation of wrap interface,
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* and shouldn't be in this kerberos-specific file. */
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/* XXX factor out common code with seal/unseal. */
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u32
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gss_wrap_kerberos(struct gss_ctx *ctx, u32 qop, int offset,
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struct xdr_buf *buf, struct page **pages)
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{
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struct krb5_ctx *kctx = ctx->internal_ctx_id;
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s32 checksum_type;
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struct xdr_netobj md5cksum = {.len = 0, .data = NULL};
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int blocksize = 0, plainlen;
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unsigned char *ptr, *krb5_hdr, *msg_start;
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s32 now;
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int headlen;
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struct page **tmp_pages;
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dprintk("RPC: gss_wrap_kerberos\n");
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now = get_seconds();
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if (qop != 0)
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goto out_err;
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switch (kctx->signalg) {
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case SGN_ALG_DES_MAC_MD5:
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checksum_type = CKSUMTYPE_RSA_MD5;
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break;
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default:
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dprintk("RPC: gss_krb5_seal: kctx->signalg %d not"
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" supported\n", kctx->signalg);
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goto out_err;
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}
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if (kctx->sealalg != SEAL_ALG_NONE && kctx->sealalg != SEAL_ALG_DES) {
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dprintk("RPC: gss_krb5_seal: kctx->sealalg %d not supported\n",
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kctx->sealalg);
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goto out_err;
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}
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blocksize = crypto_tfm_alg_blocksize(kctx->enc);
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gss_krb5_add_padding(buf, offset, blocksize);
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BUG_ON((buf->len - offset) % blocksize);
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plainlen = blocksize + buf->len - offset;
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headlen = g_token_size(&kctx->mech_used, 22 + plainlen) -
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(buf->len - offset);
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ptr = buf->head[0].iov_base + offset;
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/* shift data to make room for header. */
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/* XXX Would be cleverer to encrypt while copying. */
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/* XXX bounds checking, slack, etc. */
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memmove(ptr + headlen, ptr, buf->head[0].iov_len - offset);
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buf->head[0].iov_len += headlen;
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buf->len += headlen;
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BUG_ON((buf->len - offset - headlen) % blocksize);
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g_make_token_header(&kctx->mech_used, 22 + plainlen, &ptr);
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*ptr++ = (unsigned char) ((KG_TOK_WRAP_MSG>>8)&0xff);
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*ptr++ = (unsigned char) (KG_TOK_WRAP_MSG&0xff);
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/* ptr now at byte 2 of header described in rfc 1964, section 1.2.1: */
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krb5_hdr = ptr - 2;
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msg_start = krb5_hdr + 24;
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/* XXXJBF: */ BUG_ON(buf->head[0].iov_base + offset + headlen != msg_start + blocksize);
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*(u16 *)(krb5_hdr + 2) = htons(kctx->signalg);
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memset(krb5_hdr + 4, 0xff, 4);
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*(u16 *)(krb5_hdr + 4) = htons(kctx->sealalg);
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make_confounder(msg_start, blocksize);
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/* XXXJBF: UGH!: */
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tmp_pages = buf->pages;
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buf->pages = pages;
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if (make_checksum(checksum_type, krb5_hdr, 8, buf,
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offset + headlen - blocksize, &md5cksum))
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goto out_err;
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buf->pages = tmp_pages;
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switch (kctx->signalg) {
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case SGN_ALG_DES_MAC_MD5:
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if (krb5_encrypt(kctx->seq, NULL, md5cksum.data,
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md5cksum.data, md5cksum.len))
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goto out_err;
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memcpy(krb5_hdr + 16,
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md5cksum.data + md5cksum.len - KRB5_CKSUM_LENGTH,
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KRB5_CKSUM_LENGTH);
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dprintk("RPC: make_seal_token: cksum data: \n");
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print_hexl((u32 *) (krb5_hdr + 16), KRB5_CKSUM_LENGTH, 0);
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break;
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default:
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BUG();
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}
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kfree(md5cksum.data);
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/* XXX would probably be more efficient to compute checksum
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* and encrypt at the same time: */
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if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff,
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kctx->seq_send, krb5_hdr + 16, krb5_hdr + 8)))
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goto out_err;
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if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize,
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pages))
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goto out_err;
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kctx->seq_send++;
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return ((kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE);
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out_err:
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if (md5cksum.data) kfree(md5cksum.data);
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return GSS_S_FAILURE;
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}
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u32
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gss_unwrap_kerberos(struct gss_ctx *ctx, u32 *qop, int offset,
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struct xdr_buf *buf)
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{
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struct krb5_ctx *kctx = ctx->internal_ctx_id;
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int signalg;
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int sealalg;
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s32 checksum_type;
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struct xdr_netobj md5cksum = {.len = 0, .data = NULL};
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s32 now;
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int direction;
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s32 seqnum;
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unsigned char *ptr;
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int bodysize;
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u32 ret = GSS_S_DEFECTIVE_TOKEN;
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void *data_start, *orig_start;
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int data_len;
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int blocksize;
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dprintk("RPC: gss_unwrap_kerberos\n");
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ptr = (u8 *)buf->head[0].iov_base + offset;
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if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr,
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buf->len - offset))
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goto out;
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if ((*ptr++ != ((KG_TOK_WRAP_MSG>>8)&0xff)) ||
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(*ptr++ != (KG_TOK_WRAP_MSG &0xff)) )
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goto out;
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/* XXX sanity-check bodysize?? */
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/* get the sign and seal algorithms */
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signalg = ptr[0] + (ptr[1] << 8);
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sealalg = ptr[2] + (ptr[3] << 8);
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/* Sanity checks */
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if ((ptr[4] != 0xff) || (ptr[5] != 0xff))
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goto out;
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if (sealalg == 0xffff)
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goto out;
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/* in the current spec, there is only one valid seal algorithm per
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key type, so a simple comparison is ok */
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if (sealalg != kctx->sealalg)
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goto out;
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/* there are several mappings of seal algorithms to sign algorithms,
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but few enough that we can try them all. */
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if ((kctx->sealalg == SEAL_ALG_NONE && signalg > 1) ||
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(kctx->sealalg == SEAL_ALG_1 && signalg != SGN_ALG_3) ||
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(kctx->sealalg == SEAL_ALG_DES3KD &&
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signalg != SGN_ALG_HMAC_SHA1_DES3_KD))
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goto out;
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if (gss_decrypt_xdr_buf(kctx->enc, buf,
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ptr + 22 - (unsigned char *)buf->head[0].iov_base))
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goto out;
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/* compute the checksum of the message */
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/* initialize the the cksum */
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switch (signalg) {
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case SGN_ALG_DES_MAC_MD5:
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checksum_type = CKSUMTYPE_RSA_MD5;
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break;
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default:
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ret = GSS_S_DEFECTIVE_TOKEN;
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goto out;
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}
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switch (signalg) {
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case SGN_ALG_DES_MAC_MD5:
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ret = make_checksum(checksum_type, ptr - 2, 8, buf,
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ptr + 22 - (unsigned char *)buf->head[0].iov_base, &md5cksum);
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if (ret)
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goto out;
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ret = krb5_encrypt(kctx->seq, NULL, md5cksum.data,
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md5cksum.data, md5cksum.len);
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if (ret)
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goto out;
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if (memcmp(md5cksum.data + 8, ptr + 14, 8)) {
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ret = GSS_S_BAD_SIG;
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goto out;
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}
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break;
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default:
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ret = GSS_S_DEFECTIVE_TOKEN;
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goto out;
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}
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/* it got through unscathed. Make sure the context is unexpired */
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if (qop)
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*qop = GSS_C_QOP_DEFAULT;
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now = get_seconds();
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ret = GSS_S_CONTEXT_EXPIRED;
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if (now > kctx->endtime)
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goto out;
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/* do sequencing checks */
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ret = GSS_S_BAD_SIG;
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if ((ret = krb5_get_seq_num(kctx->seq, ptr + 14, ptr + 6, &direction,
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&seqnum)))
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goto out;
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if ((kctx->initiate && direction != 0xff) ||
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(!kctx->initiate && direction != 0))
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goto out;
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/* Copy the data back to the right position. XXX: Would probably be
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* better to copy and encrypt at the same time. */
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blocksize = crypto_tfm_alg_blocksize(kctx->enc);
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data_start = ptr + 22 + blocksize;
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orig_start = buf->head[0].iov_base + offset;
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data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
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memmove(orig_start, data_start, data_len);
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buf->head[0].iov_len -= (data_start - orig_start);
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buf->len -= (data_start - orig_start);
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ret = GSS_S_DEFECTIVE_TOKEN;
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if (gss_krb5_remove_padding(buf, blocksize))
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goto out;
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ret = GSS_S_COMPLETE;
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out:
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if (md5cksum.data) kfree(md5cksum.data);
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return ret;
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}
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Block a user