1 files changed, 302 insertions, 0 deletions
diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c
new file mode 100644
index 0000000..ae8e69b
--- /dev/null
+++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
@@ -0,0 +1,302 @@
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/sunrpc/gss_krb5.h>
+#include <linux/random.h>
+#include <linux/pagemap.h>
+#include <linux/crypto.h>
+
+#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 void
+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 = random32();
+		i = (i << 32) | random32();
+	}
+
+	switch (conflen) {
+	case 16:
+		*q++ = i++;
+		/* fall through */
+	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. */
+
+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, *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, 24 + 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,
+				GSS_KRB5_TOK_HDR_LEN + 8 + 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 + 24;
+
+	*(__be16 *)(ptr + 2) = htons(SGN_ALG_DES_MAC_MD5);
+	memset(ptr + 4, 0xff, 4);
+	*(__be16 *)(ptr + 4) = htons(SEAL_ALG_DES);
+
+	make_confounder(msg_start, blocksize);
+
+	/* XXXJBF: UGH!: */
+	tmp_pages = buf->pages;
+	buf->pages = pages;
+	if (make_checksum("md5", ptr, 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(ptr + GSS_KRB5_TOK_HDR_LEN, 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, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 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[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 != SGN_ALG_DES_MAC_MD5)
+		return GSS_S_DEFECTIVE_TOKEN;
+
+	sealalg = ptr[4] + (ptr[5] << 8);
+	if (sealalg != SEAL_ALG_DES)
+		return GSS_S_DEFECTIVE_TOKEN;
+
+	if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
+		return GSS_S_DEFECTIVE_TOKEN;
+
+	if (gss_decrypt_xdr_buf(kctx->enc, buf,
+			ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (unsigned char *)buf->head[0].iov_base))
+		return GSS_S_DEFECTIVE_TOKEN;
+
+	if (make_checksum("md5", ptr, 8, buf,
+		 ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (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 + GSS_KRB5_TOK_HDR_LEN, 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 + 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_blkcipher_blocksize(kctx->enc);
+	data_start = ptr + GSS_KRB5_TOK_HDR_LEN + 8 + 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;
+}