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Commit 113a0e45 authored by etienne's avatar etienne Committed by James Morris
Browse files

smack: fixes for unlabeled host support 



The following patch (against 2.6.29rc5) fixes a few issues in the
smack/netlabel "unlabeled host support" functionnality that was added in
2.6.29rc.  It should go in before -final.

1) smack_host_label disregard a "0.0.0.0/0 @" rule (or other label),
preventing 'tagged' tasks to access Internet (many systems drop packets with
IP options)

2) netmasks were not handled correctly, they were stored in a way _not
equivalent_ to conversion to be32 (it was equivalent for /0, /8, /16, /24,
/32 masks but not other masks)

3) smack_netlbladdr prefixes (IP/mask) were not consistent (mask&IP was not
done), so there could have been different list entries for the same IP
prefix; if those entries had different labels, well ...

4) they were not sorted

1) 2) 3) are bugs, 4) is a more cosmetic issue.
The patch :

-creates a new helper smk_netlbladdr_insert to insert a smk_netlbladdr,
-sorted by netmask length

-use the new sorted nature of  smack_netlbladdrs list to simplify
 smack_host_label : the first match _will_ be the more specific

-corrects endianness issues in smk_write_netlbladdr &  netlbladdr_seq_show

Signed-off-by: default avatar <etienne.basset@numericable.fr>
Acked-by: default avatarCasey Schaufler <casey@schaufler-ca.com>
Reviewed-by: default avatarPaul Moore <paul.moore@hp.com>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent 454804ab

security/smack/smackfs.c

+49 −15
Original line number Diff line number Diff line
@@ -651,10 +651,6 @@ static void *netlbladdr_seq_next(struct seq_file *s, void *v, loff_t *pos) 


	return skp;

}

/*

#define BEMASK	0x80000000

*/

#define BEMASK	0x00000001

#define BEBITS	(sizeof(__be32) * 8)



/*
@@ -664,12 +660,10 @@ static int netlbladdr_seq_show(struct seq_file *s, void *v) 
{

	struct smk_netlbladdr *skp = (struct smk_netlbladdr *) v;

	unsigned char *hp = (char *) &skp->smk_host.sin_addr.s_addr;

	__be32 bebits;

	int maskn = 0;

	int maskn;

	u32 temp_mask = be32_to_cpu(skp->smk_mask.s_addr);



	for (bebits = BEMASK; bebits != 0; maskn++, bebits <<= 1)

		if ((skp->smk_mask.s_addr & bebits) == 0)

			break;

	for (maskn = 0; temp_mask; temp_mask <<= 1, maskn++);



	seq_printf(s, "%u.%u.%u.%u/%d %s\n",

		hp[0], hp[1], hp[2], hp[3], maskn, skp->smk_label);
@@ -702,6 +696,42 @@ static int smk_open_netlbladdr(struct inode *inode, struct file *file) 
	return seq_open(file, &netlbladdr_seq_ops);

}



/**

 * smk_netlbladdr_insert

 * @new : netlabel to insert

 *

 * This helper insert netlabel in the smack_netlbladdrs list

 * sorted by netmask length (longest to smallest)

 */

static void smk_netlbladdr_insert(struct smk_netlbladdr *new)

{

	struct smk_netlbladdr *m;



	if (smack_netlbladdrs == NULL) {

		smack_netlbladdrs = new;

		return;

	}



	/* the comparison '>' is a bit hacky, but works */

	if (new->smk_mask.s_addr > smack_netlbladdrs->smk_mask.s_addr) {

		new->smk_next = smack_netlbladdrs;

		smack_netlbladdrs = new;

		return;

	}

	for (m = smack_netlbladdrs; m != NULL; m = m->smk_next) {

		if (m->smk_next == NULL) {

			m->smk_next = new;

			return;

		}

		if (new->smk_mask.s_addr > m->smk_next->smk_mask.s_addr) {

			new->smk_next = m->smk_next;

			m->smk_next = new;

			return;

		}

	}

}





/**

 * smk_write_netlbladdr - write() for /smack/netlabel

 * @file: file pointer, not actually used
@@ -725,8 +755,9 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf, 
	struct netlbl_audit audit_info;

	struct in_addr mask;

	unsigned int m;

	__be32 bebits = BEMASK;

	u32 mask_bits = (1<<31);

	__be32 nsa;

	u32 temp_mask;



	/*

	 * Must have privilege.
@@ -762,10 +793,13 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf, 
	if (sp == NULL)

		return -EINVAL;



	for (mask.s_addr = 0; m > 0; m--) {

		mask.s_addr |= bebits;

		bebits <<= 1;

	for (temp_mask = 0; m > 0; m--) {

		temp_mask |= mask_bits;

		mask_bits >>= 1;

	}

	mask.s_addr = cpu_to_be32(temp_mask);



	newname.sin_addr.s_addr &= mask.s_addr;

	/*

	 * Only allow one writer at a time. Writes should be

	 * quite rare and small in any case.
@@ -773,6 +807,7 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf, 
	mutex_lock(&smk_netlbladdr_lock);



	nsa = newname.sin_addr.s_addr;

	/* try to find if the prefix is already in the list */

	for (skp = smack_netlbladdrs; skp != NULL; skp = skp->smk_next)

		if (skp->smk_host.sin_addr.s_addr == nsa &&

		    skp->smk_mask.s_addr == mask.s_addr)
@@ -788,9 +823,8 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf, 
			rc = 0;

			skp->smk_host.sin_addr.s_addr = newname.sin_addr.s_addr;

			skp->smk_mask.s_addr = mask.s_addr;

			skp->smk_next = smack_netlbladdrs;

			skp->smk_label = sp;

			smack_netlbladdrs = skp;

			smk_netlbladdr_insert(skp);

		}

	} else {

		rc = netlbl_cfg_unlbl_static_del(&init_net, NULL,