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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: <etienne.basset@numericable.fr>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
etienne 2009-03-04 07:33:51 +01:00 committed by James Morris
parent 454804ab03
commit 113a0e4590
1 changed files with 49 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

64
security/smack/smackfs.c
View File

@ -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,