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netlabel: Cleanup the Smack/NetLabel code to fix incoming TCP connections

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This patch cleans up a lot of the Smack network access control code.  The
largest changes are to fix the labeling of incoming TCP connections in a
manner similar to the recent SELinux changes which use the
security_inet_conn_request() hook to label the request_sock and let the label
move to the child socket via the normal network stack mechanisms.  In addition
to the incoming TCP connection fixes this patch also removes the smk_labled
field from the socket_smack struct as the minor optimization advantage was
outweighed by the difficulty in maintaining it's proper state.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
Paul Moore 2009-03-27 17:10:54 -04:00 committed by James Morris
parent 8651d5c0b1
commit 07feee8f81
4 changed files with 161 additions and 118 deletions
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5
include/net/netlabel.h
View File

@ -417,6 +417,7 @@ int netlbl_conn_setattr(struct sock *sk,
const struct netlbl_lsm_secattr *secattr);
int netlbl_req_setattr(struct request_sock *req,
const struct netlbl_lsm_secattr *secattr);
void netlbl_req_delattr(struct request_sock *req);
int netlbl_skbuff_setattr(struct sk_buff *skb,
u16 family,
const struct netlbl_lsm_secattr *secattr);
@ -547,6 +548,10 @@ static inline int netlbl_req_setattr(struct request_sock *req,
{
return -ENOSYS;
}
static inline void netlbl_req_delattr(struct request_sock *req)
{
return;
}
static inline int netlbl_skbuff_setattr(struct sk_buff *skb,
u16 family,
const struct netlbl_lsm_secattr *secattr)

13
net/netlabel/netlabel_kapi.c
View File

@ -860,6 +860,19 @@ req_setattr_return:
return ret_val;
}
/**
* netlbl_req_delattr - Delete all the NetLabel labels on a socket
* @req: the socket
*
* Description:
* Remove all the NetLabel labeling from @req.
*
*/
void netlbl_req_delattr(struct request_sock *req)
{
cipso_v4_req_delattr(req);
}
/**
* netlbl_skbuff_setattr - Label a packet using the correct protocol
* @skb: the packet

1
security/smack/smack.h
View File

@ -42,7 +42,6 @@ struct superblock_smack {
struct socket_smack {
char *smk_out; /* outbound label */
char *smk_in; /* inbound label */
int smk_labeled; /* label scheme */
char smk_packet[SMK_LABELLEN]; /* TCP peer label */
};

260
security/smack/smack_lsm.c
View File

@ -7,6 +7,8 @@
* Casey Schaufler <casey@schaufler-ca.com>
*
* Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com>
* Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
* Paul Moore <paul.moore@hp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2,
@ -20,6 +22,7 @@
#include <linux/ext2_fs.h>
#include <linux/kd.h>
#include <asm/ioctls.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/mutex.h>
@ -1275,7 +1278,6 @@ static int smack_sk_alloc_security(struct sock *sk, int family, gfp_t gfp_flags)
ssp->smk_in = csp;
ssp->smk_out = csp;
ssp->smk_labeled = SMACK_CIPSO_SOCKET;
ssp->smk_packet[0] = '\0';
sk->sk_security = ssp;
@ -1294,6 +1296,39 @@ static void smack_sk_free_security(struct sock *sk)
kfree(sk->sk_security);
}
/**
* smack_host_label - check host based restrictions
* @sip: the object end
*
* looks for host based access restrictions
*
* This version will only be appropriate for really small sets of single label
* hosts. The caller is responsible for ensuring that the RCU read lock is
* taken before calling this function.
*
* Returns the label of the far end or NULL if it's not special.
*/
static char *smack_host_label(struct sockaddr_in *sip)
{
struct smk_netlbladdr *snp;
struct in_addr *siap = &sip->sin_addr;
if (siap->s_addr == 0)
return NULL;
list_for_each_entry_rcu(snp, &smk_netlbladdr_list, list)
/*
* we break after finding the first match because
* the list is sorted from longest to shortest mask
* so we have found the most specific match
*/
if ((&snp->smk_host.sin_addr)->s_addr ==
(siap->s_addr & (&snp->smk_mask)->s_addr))
return snp->smk_label;
return NULL;
}
/**
* smack_set_catset - convert a capset to netlabel mls categories
* @catset: the Smack categories
@ -1365,11 +1400,10 @@ static void smack_to_secattr(char *smack, struct netlbl_lsm_secattr *nlsp)
*/
static int smack_netlabel(struct sock *sk, int labeled)
{
struct socket_smack *ssp;
struct socket_smack *ssp = sk->sk_security;
struct netlbl_lsm_secattr secattr;
int rc = 0;
ssp = sk->sk_security;
/*
* Usually the netlabel code will handle changing the
* packet labeling based on the label.
@ -1393,20 +1427,44 @@ static int smack_netlabel(struct sock *sk, int labeled)
bh_unlock_sock(sk);
local_bh_enable();
/*
* Remember the label scheme used so that it is not
* necessary to do the netlabel setting if it has not
* changed the next time through.
*
* The -EDESTADDRREQ case is an indication that there's
* a single level host involved.
*/
if (rc == 0)
ssp->smk_labeled = labeled;
return rc;
}
/**
* smack_netlbel_send - Set the secattr on a socket and perform access checks
* @sk: the socket
* @sap: the destination address
*
* Set the correct secattr for the given socket based on the destination
* address and perform any outbound access checks needed.
*
* Returns 0 on success or an error code.
*
*/
static int smack_netlabel_send(struct sock *sk, struct sockaddr_in *sap)
{
int rc;
int sk_lbl;
char *hostsp;
struct socket_smack *ssp = sk->sk_security;
rcu_read_lock();
hostsp = smack_host_label(sap);
if (hostsp != NULL) {
sk_lbl = SMACK_UNLABELED_SOCKET;
rc = smk_access(ssp->smk_out, hostsp, MAY_WRITE);
} else {
sk_lbl = SMACK_CIPSO_SOCKET;
rc = 0;
}
rcu_read_unlock();
if (rc != 0)
return rc;
return smack_netlabel(sk, sk_lbl);
}
/**
* smack_inode_setsecurity - set smack xattrs
* @inode: the object
@ -1488,43 +1546,6 @@ static int smack_socket_post_create(struct socket *sock, int family,
return smack_netlabel(sock->sk, SMACK_CIPSO_SOCKET);
}
/**
* smack_host_label - check host based restrictions
* @sip: the object end
*
* looks for host based access restrictions
*
* This version will only be appropriate for really small
* sets of single label hosts.
*
* Returns the label of the far end or NULL if it's not special.
*/
static char *smack_host_label(struct sockaddr_in *sip)
{
struct smk_netlbladdr *snp;
struct in_addr *siap = &sip->sin_addr;
if (siap->s_addr == 0)
return NULL;
rcu_read_lock();
list_for_each_entry_rcu(snp, &smk_netlbladdr_list, list) {
/*
* we break after finding the first match because
* the list is sorted from longest to shortest mask
* so we have found the most specific match
*/
if ((&snp->smk_host.sin_addr)->s_addr ==
(siap->s_addr & (&snp->smk_mask)->s_addr)) {
rcu_read_unlock();
return snp->smk_label;
}
}
rcu_read_unlock();
return NULL;
}
/**
* smack_socket_connect - connect access check
* @sock: the socket
@ -1538,30 +1559,12 @@ static char *smack_host_label(struct sockaddr_in *sip)
static int smack_socket_connect(struct socket *sock, struct sockaddr *sap,
int addrlen)
{
struct socket_smack *ssp = sock->sk->sk_security;
char *hostsp;
int rc;
if (sock->sk == NULL || sock->sk->sk_family != PF_INET)
return 0;
if (addrlen < sizeof(struct sockaddr_in))
return -EINVAL;
hostsp = smack_host_label((struct sockaddr_in *)sap);
if (hostsp == NULL) {
if (ssp->smk_labeled != SMACK_CIPSO_SOCKET)
return smack_netlabel(sock->sk, SMACK_CIPSO_SOCKET);
return 0;
}
rc = smk_access(ssp->smk_out, hostsp, MAY_WRITE);
if (rc != 0)
return rc;
if (ssp->smk_labeled != SMACK_UNLABELED_SOCKET)
return smack_netlabel(sock->sk, SMACK_UNLABELED_SOCKET);
return 0;
return smack_netlabel_send(sock->sk, (struct sockaddr_in *)sap);
}
/**
@ -2262,9 +2265,6 @@ static int smack_socket_sendmsg(struct socket *sock, struct msghdr *msg,
int size)
{
struct sockaddr_in *sip = (struct sockaddr_in *) msg->msg_name;
struct socket_smack *ssp = sock->sk->sk_security;
char *hostsp;
int rc;
/*
* Perfectly reasonable for this to be NULL
@ -2272,22 +2272,7 @@ static int smack_socket_sendmsg(struct socket *sock, struct msghdr *msg,
if (sip == NULL || sip->sin_family != PF_INET)
return 0;
hostsp = smack_host_label(sip);
if (hostsp == NULL) {
if (ssp->smk_labeled != SMACK_CIPSO_SOCKET)
return smack_netlabel(sock->sk, SMACK_CIPSO_SOCKET);
return 0;
}
rc = smk_access(ssp->smk_out, hostsp, MAY_WRITE);
if (rc != 0)
return rc;
if (ssp->smk_labeled != SMACK_UNLABELED_SOCKET)
return smack_netlabel(sock->sk, SMACK_UNLABELED_SOCKET);
return 0;
return smack_netlabel_send(sock->sk, sip);
}
@ -2492,31 +2477,24 @@ static int smack_socket_getpeersec_dgram(struct socket *sock,
}
/**
* smack_sock_graft - graft access state between two sockets
* @sk: fresh sock
* @parent: donor socket
* smack_sock_graft - Initialize a newly created socket with an existing sock
* @sk: child sock
* @parent: parent socket
*
* Sets the netlabel socket state on sk from parent
* Set the smk_{in,out} state of an existing sock based on the process that
* is creating the new socket.
*/
static void smack_sock_graft(struct sock *sk, struct socket *parent)
{
struct socket_smack *ssp;
int rc;
if (sk == NULL)
return;
if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6)
if (sk == NULL ||
(sk->sk_family != PF_INET && sk->sk_family != PF_INET6))
return;
ssp = sk->sk_security;
ssp->smk_in = ssp->smk_out = current_security();
ssp->smk_packet[0] = '\0';
rc = smack_netlabel(sk, SMACK_CIPSO_SOCKET);
if (rc != 0)
printk(KERN_WARNING "Smack: \"%s\" netlbl error %d.\n",
__func__, -rc);
/* cssp->smk_packet is already set in smack_inet_csk_clone() */
}
/**
@ -2531,35 +2509,82 @@ static void smack_sock_graft(struct sock *sk, struct socket *parent)
static int smack_inet_conn_request(struct sock *sk, struct sk_buff *skb,
struct request_sock *req)
{
struct netlbl_lsm_secattr skb_secattr;
u16 family = sk->sk_family;
struct socket_smack *ssp = sk->sk_security;
struct netlbl_lsm_secattr secattr;
struct sockaddr_in addr;
struct iphdr *hdr;
char smack[SMK_LABELLEN];
int rc;
if (skb == NULL)
return -EACCES;
/* handle mapped IPv4 packets arriving via IPv6 sockets */
if (family == PF_INET6 && skb->protocol == htons(ETH_P_IP))
family = PF_INET;
netlbl_secattr_init(&skb_secattr);
rc = netlbl_skbuff_getattr(skb, sk->sk_family, &skb_secattr);
netlbl_secattr_init(&secattr);
rc = netlbl_skbuff_getattr(skb, family, &secattr);
if (rc == 0)
smack_from_secattr(&skb_secattr, smack);
smack_from_secattr(&secattr, smack);
else
strncpy(smack, smack_known_huh.smk_known, SMK_MAXLEN);
netlbl_secattr_destroy(&skb_secattr);
netlbl_secattr_destroy(&secattr);
/*
* Receiving a packet requires that the other end
* be able to write here. Read access is not required.
*
* If the request is successful save the peer's label
* so that SO_PEERCRED can report it.
* Receiving a packet requires that the other end be able to write
* here. Read access is not required.
*/
rc = smk_access(smack, ssp->smk_in, MAY_WRITE);
if (rc == 0)
strncpy(ssp->smk_packet, smack, SMK_MAXLEN);
if (rc != 0)
return rc;
/*
* Save the peer's label in the request_sock so we can later setup
* smk_packet in the child socket so that SO_PEERCRED can report it.
*/
req->peer_secid = smack_to_secid(smack);
/*
* We need to decide if we want to label the incoming connection here
* if we do we only need to label the request_sock and the stack will
* propogate the wire-label to the sock when it is created.
*/
hdr = ip_hdr(skb);
addr.sin_addr.s_addr = hdr->saddr;
rcu_read_lock();
if (smack_host_label(&addr) == NULL) {
rcu_read_unlock();
netlbl_secattr_init(&secattr);
smack_to_secattr(smack, &secattr);
rc = netlbl_req_setattr(req, &secattr);
netlbl_secattr_destroy(&secattr);
} else {
rcu_read_unlock();
netlbl_req_delattr(req);
}
return rc;
}
/**
* smack_inet_csk_clone - Copy the connection information to the new socket
* @sk: the new socket
* @req: the connection's request_sock
*
* Transfer the connection's peer label to the newly created socket.
*/
static void smack_inet_csk_clone(struct sock *sk,
const struct request_sock *req)
{
struct socket_smack *ssp = sk->sk_security;
char *smack;
if (req->peer_secid != 0) {
smack = smack_from_secid(req->peer_secid);
strncpy(ssp->smk_packet, smack, SMK_MAXLEN);
} else
ssp->smk_packet[0] = '\0';
}
/*
* Key management security hooks
*
@ -2911,6 +2936,7 @@ struct security_operations smack_ops = {
.sk_free_security = smack_sk_free_security,
.sock_graft = smack_sock_graft,
.inet_conn_request = smack_inet_conn_request,
.inet_csk_clone = smack_inet_csk_clone,
/* key management security hooks */
#ifdef CONFIG_KEYS