svcauth_gss.c

linux-2.6.15.6

/*
 * Neil Brown <[e-mail]>
 * J. Bruce Fields <[e-mail]>
 * Andy Adamson <[e-mail]>
 * Dug Song <[e-mail]>
 *
 * RPCSEC_GSS server authentication.
 * This implements RPCSEC_GSS as defined in rfc2203 (rpcsec_gss) and rfc2078
 * (gssapi)
 *
 * The RPCSEC_GSS involves three stages:
 *  1/ context creation
 *  2/ data exchange
 *  3/ context destruction
 *
 * Context creation is handled largely by upcalls to user-space.
 *  In particular, GSS_Accept_sec_context is handled by an upcall
 * Data exchange is handled entirely within the kernel
 *  In particular, GSS_GetMIC, GSS_VerifyMIC, GSS_Seal, GSS_Unseal are in-kernel.
 * Context destruction is handled in-kernel
 *  GSS_Delete_sec_context is in-kernel
 *
 * Context creation is initiated by a RPCSEC_GSS_INIT request arriving.
 * The context handle and gss_token are used as a key into the rpcsec_init cache.
 * The content of this cache includes some of the outputs of GSS_Accept_sec_context,
 * being major_status, minor_status, context_handle, reply_token.
 * These are sent back to the client.
 * Sequence window management is handled by the kernel.  The window size if currently
 * a compile time constant.
 *
 * When user-space is happy that a context is established, it places an entry
 * in the rpcsec_context cache. The key for this cache is the context_handle.
 * The content includes:
 *   uid/gidlist - for determining access rights
 *   mechanism type
 *   mechanism specific information, such as a key
 *
 */

#include <linux/types.h>
#include <linux/module.h>
#include <linux/pagemap.h>

#include <linux/sunrpc/auth_gss.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/sunrpc/gss_err.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/cache.h>

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY	RPCDBG_AUTH
#endif

/* The rpcsec_init cache is used for mapping RPCSEC_GSS_{,CONT_}INIT requests
 * into replies.
 *
 * Key is context handle (\x if empty) and gss_token.
 * Content is major_status minor_status (integers) context_handle, reply_token.
 *
 */

static int netobj_equal(struct xdr_netobj *a, struct xdr_netobj *b)
{
	return a->len == b->len && 0 == memcmp(a->data, b->data, a->len);
}

#define	RSI_HASHBITS	6
#define	RSI_HASHMAX	(1<<RSI_HASHBITS)
#define	RSI_HASHMASK	(RSI_HASHMAX-1)

struct rsi {
	struct cache_head	h;
	struct xdr_netobj	in_handle, in_token;
	struct xdr_netobj	out_handle, out_token;
	int			major_status, minor_status;
};

static struct cache_head *rsi_table[RSI_HASHMAX];
static struct cache_detail rsi_cache;
static struct rsi *rsi_lookup(struct rsi *item, int set);

static void rsi_free(struct rsi *rsii)
{
	kfree(rsii->in_handle.data);
	kfree(rsii->in_token.data);
	kfree(rsii->out_handle.data);
	kfree(rsii->out_token.data);
}

static void rsi_put(struct cache_head *item, struct cache_detail *cd)
{
	struct rsi *rsii = container_of(item, struct rsi, h);
	if (cache_put(item, cd)) {
		rsi_free(rsii);
		kfree(rsii);
	}
}

static inline int rsi_hash(struct rsi *item)
{
	return hash_mem(item->in_handle.data, item->in_handle.len, RSI_HASHBITS)
	     ^ hash_mem(item->in_token.data, item->in_token.len, RSI_HASHBITS);
}

static inline int rsi_match(struct rsi *item, struct rsi *tmp)
{
	return netobj_equal(&item->in_handle, &tmp->in_handle)
		&& netobj_equal(&item->in_token, &tmp->in_token);
}

static int dup_to_netobj(struct xdr_netobj *dst, char *src, int len)
{
	dst->len = len;
	dst->data = (len ? kmalloc(len, GFP_KERNEL) : NULL);
	if (dst->data)
		memcpy(dst->data, src, len);
	if (len && !dst->data)
		return -ENOMEM;
	return 0;
}

static inline int dup_netobj(struct xdr_netobj *dst, struct xdr_netobj *src)
{
	return dup_to_netobj(dst, src->data, src->len);
}

static inline void rsi_init(struct rsi *new, struct rsi *item)
{
	new->out_handle.data = NULL;
	new->out_handle.len = 0;
	new->out_token.data = NULL;
	new->out_token.len = 0;
	new->in_handle.len = item->in_handle.len;
	item->in_handle.len = 0;
	new->in_token.len = item->in_token.len;
	item->in_token.len = 0;
	new->in_handle.data = item->in_handle.data;
	item->in_handle.data = NULL;
	new->in_token.data = item->in_token.data;
	item->in_token.data = NULL;
}

static inline void rsi_update(struct rsi *new, struct rsi *item)
{
	BUG_ON(new->out_handle.data || new->out_token.data);
	new->out_handle.len = item->out_handle.len;
	item->out_handle.len = 0;
	new->out_token.len = item->out_token.len;
	item->out_token.len = 0;
	new->out_handle.data = item->out_handle.data;
	item->out_handle.data = NULL;
	new->out_token.data = item->out_token.data;
	item->out_token.data = NULL;

	new->major_status = item->major_status;
	new->minor_status = item->minor_status;
}

static void rsi_request(struct cache_detail *cd,
                       struct cache_head *h,
                       char **bpp, int *blen)
{
	struct rsi *rsii = container_of(h, struct rsi, h);

	qword_addhex(bpp, blen, rsii->in_handle.data, rsii->in_handle.len);
	qword_addhex(bpp, blen, rsii->in_token.data, rsii->in_token.len);
	(*bpp)[-1] = '\n';
}


static int rsi_parse(struct cache_detail *cd,
                    char *mesg, int mlen)
{
	/* context token expiry major minor context token */
	char *buf = mesg;
	char *ep;
	int len;
	struct rsi rsii, *rsip = NULL;
	time_t expiry;
	int status = -EINVAL;

	memset(&rsii, 0, sizeof(rsii));
	/* handle */
	len = qword_get(&mesg, buf, mlen);
	if (len < 0)
		goto out;
	status = -ENOMEM;
	if (dup_to_netobj(&rsii.in_handle, buf, len))
		goto out;

	/* token */
	len = qword_get(&mesg, buf, mlen);
	status = -EINVAL;
	if (len < 0)
		goto out;
	status = -ENOMEM;
	if (dup_to_netobj(&rsii.in_token, buf, len))
		goto out;

	rsii.h.flags = 0;
	/* expiry */
	expiry = get_expiry(&mesg);
	status = -EINVAL;
	if (expiry == 0)
		goto out;

	/* major/minor */
	len = qword_get(&mesg, buf, mlen);
	if (len < 0)
		goto out;
	if (len == 0) {
		goto out;
	} else {
		rsii.major_status = simple_strtoul(buf, &ep, 10);
		if (*ep)
			goto out;
		len = qword_get(&mesg, buf, mlen);
		if (len <= 0)
			goto out;
		rsii.minor_status = simple_strtoul(buf, &ep, 10);
		if (*ep)
			goto out;

		/* out_handle */
		len = qword_get(&mesg, buf, mlen);
		if (len < 0)
			goto out;
		status = -ENOMEM;
		if (dup_to_netobj(&rsii.out_handle, buf, len))
			goto out;

		/* out_token */
		len = qword_get(&mesg, buf, mlen);
		status = -EINVAL;
		if (len < 0)
			goto out;
		status = -ENOMEM;
		if (dup_to_netobj(&rsii.out_token, buf, len))
			goto out;
	}
	rsii.h.expiry_time = expiry;
	rsip = rsi_lookup(&rsii, 1);
	status = 0;
out:
	rsi_free(&rsii);
	if (rsip)
		rsi_put(&rsip->h, &rsi_cache);
	return status;
}

static struct cache_detail rsi_cache = {
	.owner		= THIS_MODULE,
	.hash_size	= RSI_HASHMAX,
	.hash_table     = rsi_table,
	.name           = "auth.rpcsec.init",
	.cache_put      = rsi_put,
	.cache_request  = rsi_request,
	.cache_parse    = rsi_parse,
};

static DefineSimpleCacheLookup(rsi, 0)

/*
 * The rpcsec_context cache is used to store a context that is
 * used in data exchange.
 * The key is a context handle. The content is:
 *  uid, gidlist, mechanism, service-set, mech-specific-data
 */

#define	RSC_HASHBITS	10
#define	RSC_HASHMAX	(1<<RSC_HASHBITS)
#define	RSC_HASHMASK	(RSC_HASHMAX-1)

#define GSS_SEQ_WIN	128

struct gss_svc_seq_data {
	/* highest seq number seen so far: */
	int			sd_max;
	/* for i such that sd_max-GSS_SEQ_WIN < i <= sd_max, the i-th bit of
	 * sd_win is nonzero iff sequence number i has been seen already: */
	unsigned long		sd_win[GSS_SEQ_WIN/BITS_PER_LONG];
	spinlock_t		sd_lock;
};

struct rsc {
	struct cache_head	h;
	struct xdr_netobj	handle;
	struct svc_cred		cred;
	struct gss_svc_seq_data	seqdata;
	struct gss_ctx		*mechctx;
};

static struct cache_head *rsc_table[RSC_HASHMAX];
static struct cache_detail rsc_cache;
static struct rsc *rsc_lookup(struct rsc *item, int set);

static void rsc_free(struct rsc *rsci)
{
	kfree(rsci->handle.data);
	if (rsci->mechctx)
		gss_delete_sec_context(&rsci->mechctx);
	if (rsci->cred.cr_group_info)
		put_group_info(rsci->cred.cr_group_info);
}

static void rsc_put(struct cache_head *item, struct cache_detail *cd)
{
	struct rsc *rsci = container_of(item, struct rsc, h);

	if (cache_put(item, cd)) {
		rsc_free(rsci);
		kfree(rsci);
	}
}

static inline int
rsc_hash(struct rsc *rsci)
{
	return hash_mem(rsci->handle.data, rsci->handle.len, RSC_HASHBITS);
}

static inline int
rsc_match(struct rsc *new, struct rsc *tmp)
{
	return netobj_equal(&new->handle, &tmp->handle);
}

static inline void
rsc_init(struct rsc *new, struct rsc *tmp)
{
	new->handle.len = tmp->handle.len;
	tmp->handle.len = 0;
	new->handle.data = tmp->handle.data;
	tmp->handle.data = NULL;
	new->mechctx = NULL;
	new->cred.cr_group_info = NULL;
}

static inline void
rsc_update(struct rsc *new, struct rsc *tmp)
{
	new->mechctx = tmp->mechctx;
	tmp->mechctx = NULL;
	memset(&new->seqdata, 0, sizeof(new->seqdata));
	spin_lock_init(&new->seqdata.sd_lock);
	new->cred = tmp->cred;
	tmp->cred.cr_group_info = NULL;
}

static int rsc_parse(struct cache_detail *cd,
		     char *mesg, int mlen)
{
	/* contexthandle expiry [ uid gid N <n gids> mechname ...mechdata... ] */
	char *buf = mesg;
	int len, rv;
	struct rsc rsci, *rscp = NULL;
	time_t expiry;
	int status = -EINVAL;

	memset(&rsci, 0, sizeof(rsci));
	/* context handle */
	len = qword_get(&mesg, buf, mlen);
	if (len < 0) goto out;
	status = -ENOMEM;
	if (dup_to_netobj(&rsci.handle, buf, len))
		goto out;

	rsci.h.flags = 0;
	/* expiry */
	expiry = get_expiry(&mesg);
	status = -EINVAL;
	if (expiry == 0)
		goto out;

	/* uid, or NEGATIVE */
	rv = get_int(&mesg, &rsci.cred.cr_uid);
	if (rv == -EINVAL)
		goto out;
	if (rv == -ENOENT)
		set_bit(CACHE_NEGATIVE, &rsci.h.flags);
	else {
		int N, i;
		struct gss_api_mech *gm;

		/* gid */
		if (get_int(&mesg, &rsci.cred.cr_gid))
			goto out;

		/* number of additional gid's */
		if (get_int(&mesg, &N))
			goto out;
		status = -ENOMEM;
		rsci.cred.cr_group_info = groups_alloc(N);
		if (rsci.cred.cr_group_info == NULL)
			goto out;

		/* gid's */
		status = -EINVAL;
		for (i=0; i<N; i++) {
			gid_t gid;
			if (get_int(&mesg, &gid))
				goto out;
			GROUP_AT(rsci.cred.cr_group_info, i) = gid;
		}

		/* mech name */
		len = qword_get(&mesg, buf, mlen);
		if (len < 0)
			goto out;
		gm = gss_mech_get_by_name(buf);
		status = -EOPNOTSUPP;
		if (!gm)
			goto out;

		status = -EINVAL;
		/* mech-specific data: */
		len = qword_get(&mesg, buf, mlen);
		if (len < 0) {
			gss_mech_put(gm);
			goto out;
		}
		if (gss_import_sec_context(buf, len, gm, &rsci.mechctx)) {
			gss_mech_put(gm);
			goto out;
		}
		gss_mech_put(gm);
	}
	rsci.h.expiry_time = expiry;
	rscp = rsc_lookup(&rsci, 1);
	status = 0;
out:
	rsc_free(&rsci);
	if (rscp)
		rsc_put(&rscp->h, &rsc_cache);
	return status;
}

static struct cache_detail rsc_cache = {
	.owner		= THIS_MODULE,
	.hash_size	= RSC_HASHMAX,
	.hash_table	= rsc_table,
	.name		= "auth.rpcsec.context",
	.cache_put	= rsc_put,
	.cache_parse	= rsc_parse,
};

static DefineSimpleCacheLookup(rsc, 0);

static struct rsc *
gss_svc_searchbyctx(struct xdr_netobj *handle)
{
	struct rsc rsci;
	struct rsc *found;

	memset(&rsci, 0, sizeof(rsci));
	if (dup_to_netobj(&rsci.handle, handle->data, handle->len))
		return NULL;
	found = rsc_lookup(&rsci, 0);
	rsc_free(&rsci);
	if (!found)
		return NULL;
	if (cache_check(&rsc_cache, &found->h, NULL))
		return NULL;
	return found;
}

/* Implements sequence number algorithm as specified in RFC 2203. */
static int
gss_check_seq_num(struct rsc *rsci, int seq_num)
{
	struct gss_svc_seq_data *sd = &rsci->seqdata;

	spin_lock(&sd->sd_lock);
	if (seq_num > sd->sd_max) {
		if (seq_num >= sd->sd_max + GSS_SEQ_WIN) {
			memset(sd->sd_win,0,sizeof(sd->sd_win));
			sd->sd_max = seq_num;
		} else while (sd->sd_max < seq_num) {
			sd->sd_max++;
			__clear_bit(sd->sd_max % GSS_SEQ_WIN, sd->sd_win);
		}
		__set_bit(seq_num % GSS_SEQ_WIN, sd->sd_win);
		goto ok;
	} else if (seq_num <= sd->sd_max - GSS_SEQ_WIN) {
		goto drop;
	}
	/* sd_max - GSS_SEQ_WIN < seq_num <= sd_max */
	if (__test_and_set_bit(seq_num % GSS_SEQ_WIN, sd->sd_win))
		goto drop;
ok:
	spin_unlock(&sd->sd_lock);
	return 1;
drop:
	spin_unlock(&sd->sd_lock);
	return 0;
}

static inline u32 round_up_to_quad(u32 i)
{
	return (i + 3 ) & ~3;
}

static inline int
svc_safe_getnetobj(struct kvec *argv, struct xdr_netobj *o)
{
	int l;

	if (argv->iov_len < 4)
		return -1;
	o->len = ntohl(svc_getu32(argv));
	l = round_up_to_quad(o->len);
	if (argv->iov_len < l)
		return -1;
	o->data = argv->iov_base;
	argv->iov_base += l;
	argv->iov_len -= l;
	return 0;
}

static inline int
svc_safe_putnetobj(struct kvec *resv, struct xdr_netobj *o)
{
	u32 *p;

	if (resv->iov_len + 4 > PAGE_SIZE)
		return -1;
	svc_putu32(resv, htonl(o->len));
	p = resv->iov_base + resv->iov_len;
	resv->iov_len += round_up_to_quad(o->len);
	if (resv->iov_len > PAGE_SIZE)
		return -1;
	memcpy(p, o->data, o->len);
	memset((u8 *)p + o->len, 0, round_up_to_quad(o->len) - o->len);
	return 0;
}

/* Verify the checksum on the header and return SVC_OK on success.
 * Otherwise, return SVC_DROP (in the case of a bad sequence number)
 * or return SVC_DENIED and indicate error in authp.
 */
static int