smack: implement logging V3
Etienne Basset [Wed, 8 Apr 2009 18:39:40 +0000 (20:39 +0200)]
This patch creates auditing functions usable by LSM to audit security
events. It provides standard dumping of FS, NET, task etc ... events
(code borrowed from SELinux)
and provides 2 callbacks to define LSM specific auditing, which should be
flexible enough to convert SELinux too.

Signed-off-by: Etienne Basset <etienne.basset@numericable.fr>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
cked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

include/linux/lsm_audit.h [new file with mode: 0644]
security/lsm_audit.c [new file with mode: 0644]

diff --git a/include/linux/lsm_audit.h b/include/linux/lsm_audit.h
new file mode 100644 (file)
index 0000000..e461b2c
--- /dev/null
@@ -0,0 +1,111 @@
+/*
+ * Common LSM logging functions
+ * Heavily borrowed from selinux/avc.h
+ *
+ * Author : Etienne BASSET  <etienne.basset@ensta.org>
+ *
+ * All credits to : Stephen Smalley, <sds@epoch.ncsc.mil>
+ * All BUGS to : Etienne BASSET  <etienne.basset@ensta.org>
+ */
+#ifndef _LSM_COMMON_LOGGING_
+#define _LSM_COMMON_LOGGING_
+
+#include <linux/stddef.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/kdev_t.h>
+#include <linux/spinlock.h>
+#include <linux/init.h>
+#include <linux/audit.h>
+#include <linux/in6.h>
+#include <linux/path.h>
+#include <linux/key.h>
+#include <linux/skbuff.h>
+#include <asm/system.h>
+
+
+/* Auxiliary data to use in generating the audit record. */
+struct common_audit_data {
+       char    type;
+#define LSM_AUDIT_DATA_FS      1
+#define LSM_AUDIT_DATA_NET     2
+#define LSM_AUDIT_DATA_CAP     3
+#define LSM_AUDIT_DATA_IPC     4
+#define LSM_AUDIT_DATA_TASK    5
+#define LSM_AUDIT_DATA_KEY     6
+       struct task_struct *tsk;
+       union   {
+               struct {
+                       struct path path;
+                       struct inode *inode;
+               } fs;
+               struct {
+                       int netif;
+                       struct sock *sk;
+                       u16 family;
+                       __be16 dport;
+                       __be16 sport;
+                       union {
+                               struct {
+                                       __be32 daddr;
+                                       __be32 saddr;
+                               } v4;
+                               struct {
+                                       struct in6_addr daddr;
+                                       struct in6_addr saddr;
+                               } v6;
+                       } fam;
+               } net;
+               int cap;
+               int ipc_id;
+               struct task_struct *tsk;
+#ifdef CONFIG_KEYS
+               struct {
+                       key_serial_t key;
+                       char *key_desc;
+               } key_struct;
+#endif
+       } u;
+       const char *function;
+       /* this union contains LSM specific data */
+       union {
+               /* SMACK data */
+               struct smack_audit_data {
+                       char *subject;
+                       char *object;
+                       char *request;
+                       int result;
+               } smack_audit_data;
+               /* SELinux data */
+               struct {
+                       u32 ssid;
+                       u32 tsid;
+                       u16 tclass;
+                       u32 requested;
+                       u32 audited;
+                       struct av_decision *avd;
+                       int result;
+               } selinux_audit_data;
+       } lsm_priv;
+       /* these callback will be implemented by a specific LSM */
+       void (*lsm_pre_audit)(struct audit_buffer *, void *);
+       void (*lsm_post_audit)(struct audit_buffer *, void *);
+};
+
+#define v4info fam.v4
+#define v6info fam.v6
+
+int ipv4_skb_to_auditdata(struct sk_buff *skb,
+               struct common_audit_data *ad, u8 *proto);
+
+int ipv6_skb_to_auditdata(struct sk_buff *skb,
+               struct common_audit_data *ad, u8 *proto);
+
+/* Initialize an LSM audit data structure. */
+#define COMMON_AUDIT_DATA_INIT(_d, _t) \
+       { memset((_d), 0, sizeof(struct common_audit_data)); \
+        (_d)->type = LSM_AUDIT_DATA_##_t; (_d)->function = __func__; }
+
+void common_lsm_audit(struct common_audit_data *a);
+
+#endif
diff --git a/security/lsm_audit.c b/security/lsm_audit.c
new file mode 100644 (file)
index 0000000..94b8684
--- /dev/null
@@ -0,0 +1,386 @@
+/*
+ * 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/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;
+
+       ip6 = ipv6_hdr(skb);
+       if (ip6 == NULL)
+               return -EINVAL;
+       ipv6_addr_copy(&ad->u.net.v6info.saddr, &ip6->saddr);
+       ipv6_addr_copy(&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);
+       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=%pI6", 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 inode *inode = NULL;
+       struct task_struct *tsk = current;
+
+       if (a->tsk)
+               tsk = a->tsk;
+       if (tsk && tsk->pid) {
+               audit_log_format(ab, " pid=%d comm=", tsk->pid);
+               audit_log_untrustedstring(ab, tsk->comm);
+       }
+
+       switch (a->type) {
+       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_FS:
+               if (a->u.fs.path.dentry) {
+                       struct dentry *dentry = a->u.fs.path.dentry;
+                       if (a->u.fs.path.mnt) {
+                               audit_log_d_path(ab, "path=", &a->u.fs.path);
+                       } else {
+                               audit_log_format(ab, " name=");
+                               audit_log_untrustedstring(ab,
+                                                dentry->d_name.name);
+                       }
+                       inode = dentry->d_inode;
+               } else if (a->u.fs.inode) {
+                       struct dentry *dentry;
+                       inode = a->u.fs.inode;
+                       dentry = d_find_alias(inode);
+                       if (dentry) {
+                               audit_log_format(ab, " name=");
+                               audit_log_untrustedstring(ab,
+                                                dentry->d_name.name);
+                               dput(dentry);
+                       }
+               }
+               if (inode)
+                       audit_log_format(ab, " dev=%s ino=%lu",
+                                       inode->i_sb->s_id,
+                                       inode->i_ino);
+               break;
+       case LSM_AUDIT_DATA_TASK:
+               tsk = a->u.tsk;
+               if (tsk && tsk->pid) {
+                       audit_log_format(ab, " pid=%d comm=", tsk->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->rcv_saddr,
+                                               inet->sport,
+                                               "laddr", "lport");
+                               print_ipv4_addr(ab, inet->daddr,
+                                               inet->dport,
+                                               "faddr", "fport");
+                               break;
+                       }
+                       case AF_INET6: {
+                               struct inet_sock *inet = inet_sk(sk);
+                               struct ipv6_pinfo *inet6 = inet6_sk(sk);
+
+                               print_ipv6_addr(ab, &inet6->rcv_saddr,
+                                               inet->sport,
+                                               "laddr", "lport");
+                               print_ipv6_addr(ab, &inet6->daddr,
+                                               inet->dport,
+                                               "faddr", "fport");
+                               break;
+                       }
+                       case AF_UNIX:
+                               u = unix_sk(sk);
+                               if (u->dentry) {
+                                       struct path path = {
+                                               .dentry = u->dentry,
+                                               .mnt = u->mnt
+                                       };
+                                       audit_log_d_path(ab, "path=", &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
+       } /* switch (a->type) */
+}
+
+/**
+ * common_lsm_audit - generic LSM auditing function
+ * @a:  auxiliary audit data
+ *
+ * setup the audit buffer for common security information
+ * uses callback to print LSM specific information
+ */
+void common_lsm_audit(struct common_audit_data *a)
+{
+       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, AUDIT_AVC);
+
+       if (ab == NULL)
+               return;
+
+       if (a->lsm_pre_audit)
+               a->lsm_pre_audit(ab, a);
+
+       dump_common_audit_data(ab, a);
+
+       if (a->lsm_post_audit)
+               a->lsm_post_audit(ab, a);
+
+       audit_log_end(ab);
+}