/*
   * common LSM auditing functions
   *
   * Based on code written for SELinux by :
   *			Stephen Smalley, <sds@epoch.ncsc.mil>
   * 			James Morris <jmorris@redhat.com>
   * Author : Etienne Basset, <etienne.basset@ensta.org>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2,
   * as published by the Free Software Foundation.
   */
  
  #include <linux/types.h>
  #include <linux/stddef.h>
  #include <linux/kernel.h>

  #include <linux/gfp.h>

  #include <linux/fs.h>
  #include <linux/init.h>
  #include <net/sock.h>
  #include <linux/un.h>
  #include <net/af_unix.h>
  #include <linux/audit.h>
  #include <linux/ipv6.h>
  #include <linux/ip.h>
  #include <net/ip.h>
  #include <net/ipv6.h>
  #include <linux/tcp.h>
  #include <linux/udp.h>
  #include <linux/dccp.h>
  #include <linux/sctp.h>
  #include <linux/lsm_audit.h>
  
  /**
   * ipv4_skb_to_auditdata : fill auditdata from skb
   * @skb : the skb
   * @ad : the audit data to fill
   * @proto : the layer 4 protocol
   *
   * return  0 on success
   */
  int ipv4_skb_to_auditdata(struct sk_buff *skb,
  		struct common_audit_data *ad, u8 *proto)
  {
  	int ret = 0;
  	struct iphdr *ih;
  
  	ih = ip_hdr(skb);
  	if (ih == NULL)
  		return -EINVAL;

  	ad->u.net->v4info.saddr = ih->saddr;
  	ad->u.net->v4info.daddr = ih->daddr;

  
  	if (proto)
  		*proto = ih->protocol;
  	/* non initial fragment */
  	if (ntohs(ih->frag_off) & IP_OFFSET)
  		return 0;
  
  	switch (ih->protocol) {
  	case IPPROTO_TCP: {
  		struct tcphdr *th = tcp_hdr(skb);
  		if (th == NULL)
  			break;

  		ad->u.net->sport = th->source;
  		ad->u.net->dport = th->dest;

  		break;
  	}
  	case IPPROTO_UDP: {
  		struct udphdr *uh = udp_hdr(skb);
  		if (uh == NULL)
  			break;

  		ad->u.net->sport = uh->source;
  		ad->u.net->dport = uh->dest;

  		break;
  	}
  	case IPPROTO_DCCP: {
  		struct dccp_hdr *dh = dccp_hdr(skb);
  		if (dh == NULL)
  			break;

  		ad->u.net->sport = dh->dccph_sport;
  		ad->u.net->dport = dh->dccph_dport;

  		break;
  	}
  	case IPPROTO_SCTP: {
  		struct sctphdr *sh = sctp_hdr(skb);
  		if (sh == NULL)
  			break;

  		ad->u.net->sport = sh->source;
  		ad->u.net->dport = sh->dest;

  		break;
  	}
  	default:
  		ret = -EINVAL;
  	}
  	return ret;
  }
  #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
  /**
   * ipv6_skb_to_auditdata : fill auditdata from skb
   * @skb : the skb
   * @ad : the audit data to fill
   * @proto : the layer 4 protocol
   *
   * return  0 on success
   */
  int ipv6_skb_to_auditdata(struct sk_buff *skb,
  		struct common_audit_data *ad, u8 *proto)
  {
  	int offset, ret = 0;
  	struct ipv6hdr *ip6;
  	u8 nexthdr;

  	__be16 frag_off;

  
  	ip6 = ipv6_hdr(skb);
  	if (ip6 == NULL)
  		return -EINVAL;

  	ad->u.net->v6info.saddr = ip6->saddr;
  	ad->u.net->v6info.daddr = ip6->daddr;

  	ret = 0;
  	/* IPv6 can have several extension header before the Transport header
  	 * skip them */
  	offset = skb_network_offset(skb);
  	offset += sizeof(*ip6);
  	nexthdr = ip6->nexthdr;

  	offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);

  	if (offset < 0)
  		return 0;
  	if (proto)
  		*proto = nexthdr;
  	switch (nexthdr) {
  	case IPPROTO_TCP: {
  		struct tcphdr _tcph, *th;
  
  		th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
  		if (th == NULL)
  			break;

  		ad->u.net->sport = th->source;
  		ad->u.net->dport = th->dest;

  		break;
  	}
  	case IPPROTO_UDP: {
  		struct udphdr _udph, *uh;
  
  		uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
  		if (uh == NULL)
  			break;

  		ad->u.net->sport = uh->source;
  		ad->u.net->dport = uh->dest;

  		break;
  	}
  	case IPPROTO_DCCP: {
  		struct dccp_hdr _dccph, *dh;
  
  		dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
  		if (dh == NULL)
  			break;

  		ad->u.net->sport = dh->dccph_sport;
  		ad->u.net->dport = dh->dccph_dport;

  		break;
  	}
  	case IPPROTO_SCTP: {
  		struct sctphdr _sctph, *sh;
  
  		sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph);
  		if (sh == NULL)
  			break;

  		ad->u.net->sport = sh->source;
  		ad->u.net->dport = sh->dest;

  		break;
  	}
  	default:
  		ret = -EINVAL;
  	}
  	return ret;
  }
  #endif
  
  
  static inline void print_ipv6_addr(struct audit_buffer *ab,
  				   struct in6_addr *addr, __be16 port,
  				   char *name1, char *name2)
  {
  	if (!ipv6_addr_any(addr))

  		audit_log_format(ab, " %s=%pI6c", name1, addr);

  	if (port)
  		audit_log_format(ab, " %s=%d", name2, ntohs(port));
  }
  
  static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
  				   __be16 port, char *name1, char *name2)
  {
  	if (addr)
  		audit_log_format(ab, " %s=%pI4", name1, &addr);
  	if (port)
  		audit_log_format(ab, " %s=%d", name2, ntohs(port));
  }
  
  /**
   * dump_common_audit_data - helper to dump common audit data
   * @a : common audit data
   *
   */
  static void dump_common_audit_data(struct audit_buffer *ab,
  				   struct common_audit_data *a)
  {

  	struct task_struct *tsk = current;

  	/*
  	 * To keep stack sizes in check force programers to notice if they
  	 * start making this union too large!  See struct lsm_network_audit
  	 * as an example of how to deal with large data.
  	 */
  	BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);

  	audit_log_format(ab, " pid=%d comm=", task_pid_nr(tsk));

  	audit_log_untrustedstring(ab, tsk->comm);

  
  	switch (a->type) {

  	case LSM_AUDIT_DATA_NONE:

  		return;

  	case LSM_AUDIT_DATA_IPC:
  		audit_log_format(ab, " key=%d ", a->u.ipc_id);
  		break;
  	case LSM_AUDIT_DATA_CAP:
  		audit_log_format(ab, " capability=%d ", a->u.cap);
  		break;

  	case LSM_AUDIT_DATA_PATH: {

  		struct inode *inode;

  		audit_log_d_path(ab, " path=", &a->u.path);

  
  		inode = a->u.path.dentry->d_inode;

  		if (inode) {
  			audit_log_format(ab, " dev=");
  			audit_log_untrustedstring(ab, inode->i_sb->s_id);
  			audit_log_format(ab, " ino=%lu", inode->i_ino);
  		}

  		break;
  	}
  	case LSM_AUDIT_DATA_DENTRY: {
  		struct inode *inode;
  
  		audit_log_format(ab, " name=");
  		audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
  
  		inode = a->u.dentry->d_inode;

  		if (inode) {
  			audit_log_format(ab, " dev=");
  			audit_log_untrustedstring(ab, inode->i_sb->s_id);
  			audit_log_format(ab, " ino=%lu", inode->i_ino);
  		}

  		break;

  	}
  	case LSM_AUDIT_DATA_INODE: {
  		struct dentry *dentry;
  		struct inode *inode;
  
  		inode = a->u.inode;
  		dentry = d_find_alias(inode);
  		if (dentry) {
  			audit_log_format(ab, " name=");
  			audit_log_untrustedstring(ab,
  					 dentry->d_name.name);
  			dput(dentry);
  		}

  		audit_log_format(ab, " dev=");
  		audit_log_untrustedstring(ab, inode->i_sb->s_id);
  		audit_log_format(ab, " ino=%lu", inode->i_ino);

  		break;
  	}

  	case LSM_AUDIT_DATA_TASK:
  		tsk = a->u.tsk;

  		if (tsk) {
  			pid_t pid = task_pid_nr(tsk);
  			if (pid) {
  				audit_log_format(ab, " pid=%d comm=", pid);
  				audit_log_untrustedstring(ab, tsk->comm);
  			}

  		}
  		break;
  	case LSM_AUDIT_DATA_NET:

  		if (a->u.net->sk) {
  			struct sock *sk = a->u.net->sk;

  			struct unix_sock *u;
  			int len = 0;
  			char *p = NULL;
  
  			switch (sk->sk_family) {
  			case AF_INET: {
  				struct inet_sock *inet = inet_sk(sk);

  				print_ipv4_addr(ab, inet->inet_rcv_saddr,
  						inet->inet_sport,

  						"laddr", "lport");

  				print_ipv4_addr(ab, inet->inet_daddr,
  						inet->inet_dport,

  						"faddr", "fport");
  				break;
  			}

  #if IS_ENABLED(CONFIG_IPV6)

  			case AF_INET6: {
  				struct inet_sock *inet = inet_sk(sk);

  				print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr,

  						inet->inet_sport,

  						"laddr", "lport");

  				print_ipv6_addr(ab, &sk->sk_v6_daddr,

  						inet->inet_dport,

  						"faddr", "fport");
  				break;
  			}

  #endif

  			case AF_UNIX:
  				u = unix_sk(sk);

  				if (u->path.dentry) {
  					audit_log_d_path(ab, " path=", &u->path);

  					break;
  				}
  				if (!u->addr)
  					break;
  				len = u->addr->len-sizeof(short);
  				p = &u->addr->name->sun_path[0];
  				audit_log_format(ab, " path=");
  				if (*p)
  					audit_log_untrustedstring(ab, p);
  				else
  					audit_log_n_hex(ab, p, len);
  				break;
  			}
  		}

  		switch (a->u.net->family) {

  		case AF_INET:

  			print_ipv4_addr(ab, a->u.net->v4info.saddr,
  					a->u.net->sport,

  					"saddr", "src");

  			print_ipv4_addr(ab, a->u.net->v4info.daddr,
  					a->u.net->dport,

  					"daddr", "dest");
  			break;
  		case AF_INET6:

  			print_ipv6_addr(ab, &a->u.net->v6info.saddr,
  					a->u.net->sport,

  					"saddr", "src");

  			print_ipv6_addr(ab, &a->u.net->v6info.daddr,
  					a->u.net->dport,

  					"daddr", "dest");
  			break;
  		}

  		if (a->u.net->netif > 0) {

  			struct net_device *dev;
  
  			/* NOTE: we always use init's namespace */

  			dev = dev_get_by_index(&init_net, a->u.net->netif);

  			if (dev) {
  				audit_log_format(ab, " netif=%s", dev->name);
  				dev_put(dev);
  			}
  		}
  		break;
  #ifdef CONFIG_KEYS
  	case LSM_AUDIT_DATA_KEY:
  		audit_log_format(ab, " key_serial=%u", a->u.key_struct.key);
  		if (a->u.key_struct.key_desc) {
  			audit_log_format(ab, " key_desc=");
  			audit_log_untrustedstring(ab, a->u.key_struct.key_desc);
  		}
  		break;
  #endif

  	case LSM_AUDIT_DATA_KMOD:
  		audit_log_format(ab, " kmod=");
  		audit_log_untrustedstring(ab, a->u.kmod_name);
  		break;

  	} /* switch (a->type) */
  }
  
  /**
   * common_lsm_audit - generic LSM auditing function
   * @a:  auxiliary audit data

   * @pre_audit: lsm-specific pre-audit callback
   * @post_audit: lsm-specific post-audit callback

   *
   * setup the audit buffer for common security information
   * uses callback to print LSM specific information
   */

  void common_lsm_audit(struct common_audit_data *a,
  	void (*pre_audit)(struct audit_buffer *, void *),
  	void (*post_audit)(struct audit_buffer *, void *))

  {
  	struct audit_buffer *ab;
  
  	if (a == NULL)
  		return;
  	/* we use GFP_ATOMIC so we won't sleep */

  	ab = audit_log_start(current->audit_context, GFP_ATOMIC | __GFP_NOWARN,
  			     AUDIT_AVC);

  
  	if (ab == NULL)
  		return;

  	if (pre_audit)
  		pre_audit(ab, a);

  
  	dump_common_audit_data(ab, a);

  	if (post_audit)
  		post_audit(ab, a);

  
  	audit_log_end(ab);
  }