303 lines
8.6 KiB
C
303 lines
8.6 KiB
C
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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 <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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size_t 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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unsigned int last = (buf->page_base + len - 1)
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>>PAGE_CACHE_SHIFT;
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unsigned 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_USER0);
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pad = *(ptr + offset);
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kunmap_atomic(ptr, KM_USER0);
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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 void
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make_confounder(char *p, u32 conflen)
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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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/* initialize to random value */
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if (i == 0) {
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i = random32();
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i = (i << 32) | random32();
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}
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switch (conflen) {
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case 16:
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*q++ = i++;
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/* fall through */
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case 8:
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*q++ = i++;
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break;
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default:
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BUG();
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}
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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, 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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char cksumdata[16];
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struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata};
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int blocksize = 0, plainlen;
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unsigned char *ptr, *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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u32 seq_send;
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dprintk("RPC: gss_wrap_kerberos\n");
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now = get_seconds();
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blocksize = crypto_blkcipher_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, 24 + 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,
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GSS_KRB5_TOK_HDR_LEN + 8 + plainlen, &ptr);
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/* ptr now at header described in rfc 1964, section 1.2.1: */
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ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff);
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ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff);
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msg_start = ptr + 24;
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*(__be16 *)(ptr + 2) = htons(SGN_ALG_DES_MAC_MD5);
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memset(ptr + 4, 0xff, 4);
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*(__be16 *)(ptr + 4) = htons(SEAL_ALG_DES);
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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("md5", ptr, 8, buf,
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offset + headlen - blocksize, &md5cksum))
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return GSS_S_FAILURE;
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buf->pages = tmp_pages;
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if (krb5_encrypt(kctx->seq, NULL, md5cksum.data,
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md5cksum.data, md5cksum.len))
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return GSS_S_FAILURE;
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memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data + md5cksum.len - 8, 8);
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spin_lock(&krb5_seq_lock);
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seq_send = kctx->seq_send++;
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spin_unlock(&krb5_seq_lock);
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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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seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8)))
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return GSS_S_FAILURE;
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if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize,
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pages))
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return GSS_S_FAILURE;
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return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
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}
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u32
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gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, 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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char cksumdata[16];
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struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata};
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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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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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return GSS_S_DEFECTIVE_TOKEN;
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if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
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(ptr[1] != (KG_TOK_WRAP_MSG & 0xff)))
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return GSS_S_DEFECTIVE_TOKEN;
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/* XXX sanity-check bodysize?? */
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/* get the sign and seal algorithms */
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signalg = ptr[2] + (ptr[3] << 8);
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if (signalg != SGN_ALG_DES_MAC_MD5)
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return GSS_S_DEFECTIVE_TOKEN;
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sealalg = ptr[4] + (ptr[5] << 8);
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if (sealalg != SEAL_ALG_DES)
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return GSS_S_DEFECTIVE_TOKEN;
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if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
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return GSS_S_DEFECTIVE_TOKEN;
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if (gss_decrypt_xdr_buf(kctx->enc, buf,
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ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (unsigned char *)buf->head[0].iov_base))
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return GSS_S_DEFECTIVE_TOKEN;
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if (make_checksum("md5", ptr, 8, buf,
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ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (unsigned char *)buf->head[0].iov_base, &md5cksum))
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return GSS_S_FAILURE;
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if (krb5_encrypt(kctx->seq, NULL, md5cksum.data,
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md5cksum.data, md5cksum.len))
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return GSS_S_FAILURE;
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if (memcmp(md5cksum.data + 8, ptr + GSS_KRB5_TOK_HDR_LEN, 8))
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return GSS_S_BAD_SIG;
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/* it got through unscathed. Make sure the context is unexpired */
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now = get_seconds();
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if (now > kctx->endtime)
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return GSS_S_CONTEXT_EXPIRED;
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/* do sequencing checks */
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if (krb5_get_seq_num(kctx->seq, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8,
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&direction, &seqnum))
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return GSS_S_BAD_SIG;
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if ((kctx->initiate && direction != 0xff) ||
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(!kctx->initiate && direction != 0))
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return GSS_S_BAD_SIG;
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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_blkcipher_blocksize(kctx->enc);
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data_start = ptr + GSS_KRB5_TOK_HDR_LEN + 8 + 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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if (gss_krb5_remove_padding(buf, blocksize))
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return GSS_S_DEFECTIVE_TOKEN;
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return GSS_S_COMPLETE;
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}
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