• V
    [NetLabel]: SELinux support · 7420ed23
    Venkat Yekkirala 提交于
    Add NetLabel support to the SELinux LSM and modify the
    socket_post_create() LSM hook to return an error code.  The most
    significant part of this patch is the addition of NetLabel hooks into
    the following SELinux LSM hooks:
    
     * selinux_file_permission()
     * selinux_socket_sendmsg()
     * selinux_socket_post_create()
     * selinux_socket_sock_rcv_skb()
     * selinux_socket_getpeersec_stream()
     * selinux_socket_getpeersec_dgram()
     * selinux_sock_graft()
     * selinux_inet_conn_request()
    
    The basic reasoning behind this patch is that outgoing packets are
    "NetLabel'd" by labeling their socket and the NetLabel security
    attributes are checked via the additional hook in
    selinux_socket_sock_rcv_skb().  NetLabel itself is only a labeling
    mechanism, similar to filesystem extended attributes, it is up to the
    SELinux enforcement mechanism to perform the actual access checks.
    
    In addition to the changes outlined above this patch also includes
    some changes to the extended bitmap (ebitmap) and multi-level security
    (mls) code to import and export SELinux TE/MLS attributes into and out
    of NetLabel.
    Signed-off-by: NPaul Moore <paul.moore@hp.com>
    Signed-off-by: NDavid S. Miller <davem@davemloft.net>
    7420ed23
ebitmap.c 8.6 KB
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/*
 * Implementation of the extensible bitmap type.
 *
 * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
 */
/*
 * Updated: Hewlett-Packard <paul.moore@hp.com>
 *
 *      Added ebitmap_export() and ebitmap_import()
 *
 * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include "ebitmap.h"
#include "policydb.h"

int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2)
{
	struct ebitmap_node *n1, *n2;

	if (e1->highbit != e2->highbit)
		return 0;

	n1 = e1->node;
	n2 = e2->node;
	while (n1 && n2 &&
	       (n1->startbit == n2->startbit) &&
	       (n1->map == n2->map)) {
		n1 = n1->next;
		n2 = n2->next;
	}

	if (n1 || n2)
		return 0;

	return 1;
}

int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src)
{
	struct ebitmap_node *n, *new, *prev;

	ebitmap_init(dst);
	n = src->node;
	prev = NULL;
	while (n) {
		new = kzalloc(sizeof(*new), GFP_ATOMIC);
		if (!new) {
			ebitmap_destroy(dst);
			return -ENOMEM;
		}
		new->startbit = n->startbit;
		new->map = n->map;
		new->next = NULL;
		if (prev)
			prev->next = new;
		else
			dst->node = new;
		prev = new;
		n = n->next;
	}

	dst->highbit = src->highbit;
	return 0;
}

/**
 * ebitmap_export - Export an ebitmap to a unsigned char bitmap string
 * @src: the ebitmap to export
 * @dst: the resulting bitmap string
 * @dst_len: length of dst in bytes
 *
 * Description:
 * Allocate a buffer at least src->highbit bits long and export the extensible
 * bitmap into the buffer.  The bitmap string will be in little endian format,
 * i.e. LSB first.  The value returned in dst_len may not the true size of the
 * buffer as the length of the buffer is rounded up to a multiple of MAPTYPE.
 * The caller must free the buffer when finished. Returns zero on success,
 * negative values on failure.
 *
 */
int ebitmap_export(const struct ebitmap *src,
		   unsigned char **dst,
		   size_t *dst_len)
{
	size_t bitmap_len;
	unsigned char *bitmap;
	struct ebitmap_node *iter_node;
	MAPTYPE node_val;
	size_t bitmap_byte;
	unsigned char bitmask;

	bitmap_len = src->highbit / 8;
	if (src->highbit % 7)
		bitmap_len += 1;
	if (bitmap_len == 0)
		return -EINVAL;

	bitmap = kzalloc((bitmap_len & ~(sizeof(MAPTYPE) - 1)) +
			 sizeof(MAPTYPE),
			 GFP_ATOMIC);
	if (bitmap == NULL)
		return -ENOMEM;

	iter_node = src->node;
	do {
		bitmap_byte = iter_node->startbit / 8;
		bitmask = 0x80;
		node_val = iter_node->map;
		do {
			if (bitmask == 0) {
				bitmap_byte++;
				bitmask = 0x80;
			}
			if (node_val & (MAPTYPE)0x01)
				bitmap[bitmap_byte] |= bitmask;
			node_val >>= 1;
			bitmask >>= 1;
		} while (node_val > 0);
		iter_node = iter_node->next;
	} while (iter_node);

	*dst = bitmap;
	*dst_len = bitmap_len;
	return 0;
}

/**
 * ebitmap_import - Import an unsigned char bitmap string into an ebitmap
 * @src: the bitmap string
 * @src_len: the bitmap length in bytes
 * @dst: the empty ebitmap
 *
 * Description:
 * This function takes a little endian bitmap string in src and imports it into
 * the ebitmap pointed to by dst.  Returns zero on success, negative values on
 * failure.
 *
 */
int ebitmap_import(const unsigned char *src,
		   size_t src_len,
		   struct ebitmap *dst)
{
	size_t src_off = 0;
	struct ebitmap_node *node_new;
	struct ebitmap_node *node_last = NULL;
	size_t iter;
	size_t iter_bit;
	size_t iter_limit;
	unsigned char src_byte;

	do {
		iter_limit = src_len - src_off;
		if (iter_limit >= sizeof(MAPTYPE)) {
			if (*(MAPTYPE *)&src[src_off] == 0) {
				src_off += sizeof(MAPTYPE);
				continue;
			}
			iter_limit = sizeof(MAPTYPE);
		} else {
			iter = src_off;
			src_byte = 0;
			do {
				src_byte |= src[iter++];
			} while (iter < src_len && src_byte == 0);
			if (src_byte == 0)
				break;
		}

		node_new = kzalloc(sizeof(*node_new), GFP_ATOMIC);
		if (unlikely(node_new == NULL)) {
			ebitmap_destroy(dst);
			return -ENOMEM;
		}
		node_new->startbit = src_off * 8;
		iter = 0;
		do {
			src_byte = src[src_off++];
			iter_bit = iter++ * 8;
			while (src_byte != 0) {
				if (src_byte & 0x80)
					node_new->map |= MAPBIT << iter_bit;
				iter_bit++;
				src_byte <<= 1;
			}
		} while (iter < iter_limit);

		if (node_last != NULL)
			node_last->next = node_new;
		else
			dst->node = node_new;
		node_last = node_new;
	} while (src_off < src_len);

	if (likely(node_last != NULL))
		dst->highbit = node_last->startbit + MAPSIZE;
	else
		ebitmap_init(dst);

	return 0;
}

int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2)
{
	struct ebitmap_node *n1, *n2;

	if (e1->highbit < e2->highbit)
		return 0;

	n1 = e1->node;
	n2 = e2->node;
	while (n1 && n2 && (n1->startbit <= n2->startbit)) {
		if (n1->startbit < n2->startbit) {
			n1 = n1->next;
			continue;
		}
		if ((n1->map & n2->map) != n2->map)
			return 0;

		n1 = n1->next;
		n2 = n2->next;
	}

	if (n2)
		return 0;

	return 1;
}

int ebitmap_get_bit(struct ebitmap *e, unsigned long bit)
{
	struct ebitmap_node *n;

	if (e->highbit < bit)
		return 0;

	n = e->node;
	while (n && (n->startbit <= bit)) {
		if ((n->startbit + MAPSIZE) > bit) {
			if (n->map & (MAPBIT << (bit - n->startbit)))
				return 1;
			else
				return 0;
		}
		n = n->next;
	}

	return 0;
}

int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value)
{
	struct ebitmap_node *n, *prev, *new;

	prev = NULL;
	n = e->node;
	while (n && n->startbit <= bit) {
		if ((n->startbit + MAPSIZE) > bit) {
			if (value) {
				n->map |= (MAPBIT << (bit - n->startbit));
			} else {
				n->map &= ~(MAPBIT << (bit - n->startbit));
				if (!n->map) {
					/* drop this node from the bitmap */

					if (!n->next) {
						/*
						 * this was the highest map
						 * within the bitmap
						 */
						if (prev)
							e->highbit = prev->startbit + MAPSIZE;
						else
							e->highbit = 0;
					}
					if (prev)
						prev->next = n->next;
					else
						e->node = n->next;

					kfree(n);
				}
			}
			return 0;
		}
		prev = n;
		n = n->next;
	}

	if (!value)
		return 0;

	new = kzalloc(sizeof(*new), GFP_ATOMIC);
	if (!new)
		return -ENOMEM;

	new->startbit = bit & ~(MAPSIZE - 1);
	new->map = (MAPBIT << (bit - new->startbit));

	if (!n)
		/* this node will be the highest map within the bitmap */
		e->highbit = new->startbit + MAPSIZE;

	if (prev) {
		new->next = prev->next;
		prev->next = new;
	} else {
		new->next = e->node;
		e->node = new;
	}

	return 0;
}

void ebitmap_destroy(struct ebitmap *e)
{
	struct ebitmap_node *n, *temp;

	if (!e)
		return;

	n = e->node;
	while (n) {
		temp = n;
		n = n->next;
		kfree(temp);
	}

	e->highbit = 0;
	e->node = NULL;
	return;
}

int ebitmap_read(struct ebitmap *e, void *fp)
{
	int rc;
	struct ebitmap_node *n, *l;
	__le32 buf[3];
	u32 mapsize, count, i;
	__le64 map;

	ebitmap_init(e);

	rc = next_entry(buf, fp, sizeof buf);
	if (rc < 0)
		goto out;

	mapsize = le32_to_cpu(buf[0]);
	e->highbit = le32_to_cpu(buf[1]);
	count = le32_to_cpu(buf[2]);

	if (mapsize != MAPSIZE) {
		printk(KERN_ERR "security: ebitmap: map size %u does not "
		       "match my size %Zd (high bit was %d)\n", mapsize,
		       MAPSIZE, e->highbit);
		goto bad;
	}
	if (!e->highbit) {
		e->node = NULL;
		goto ok;
	}
	if (e->highbit & (MAPSIZE - 1)) {
		printk(KERN_ERR "security: ebitmap: high bit (%d) is not a "
		       "multiple of the map size (%Zd)\n", e->highbit, MAPSIZE);
		goto bad;
	}
	l = NULL;
	for (i = 0; i < count; i++) {
		rc = next_entry(buf, fp, sizeof(u32));
		if (rc < 0) {
			printk(KERN_ERR "security: ebitmap: truncated map\n");
			goto bad;
		}
		n = kzalloc(sizeof(*n), GFP_KERNEL);
		if (!n) {
			printk(KERN_ERR "security: ebitmap: out of memory\n");
			rc = -ENOMEM;
			goto bad;
		}

		n->startbit = le32_to_cpu(buf[0]);

		if (n->startbit & (MAPSIZE - 1)) {
			printk(KERN_ERR "security: ebitmap start bit (%d) is "
			       "not a multiple of the map size (%Zd)\n",
			       n->startbit, MAPSIZE);
			goto bad_free;
		}
		if (n->startbit > (e->highbit - MAPSIZE)) {
			printk(KERN_ERR "security: ebitmap start bit (%d) is "
			       "beyond the end of the bitmap (%Zd)\n",
			       n->startbit, (e->highbit - MAPSIZE));
			goto bad_free;
		}
		rc = next_entry(&map, fp, sizeof(u64));
		if (rc < 0) {
			printk(KERN_ERR "security: ebitmap: truncated map\n");
			goto bad_free;
		}
		n->map = le64_to_cpu(map);

		if (!n->map) {
			printk(KERN_ERR "security: ebitmap: null map in "
			       "ebitmap (startbit %d)\n", n->startbit);
			goto bad_free;
		}
		if (l) {
			if (n->startbit <= l->startbit) {
				printk(KERN_ERR "security: ebitmap: start "
				       "bit %d comes after start bit %d\n",
				       n->startbit, l->startbit);
				goto bad_free;
			}
			l->next = n;
		} else
			e->node = n;

		l = n;
	}

ok:
	rc = 0;
out:
	return rc;
bad_free:
	kfree(n);
bad:
	if (!rc)
		rc = -EINVAL;
	ebitmap_destroy(e);
	goto out;
}
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