1:39 p.m.
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(a)numericable.fr>
---
include/linux/lsm_audit.h | 111 +++++++++++++
security/lsm_audit.c | 386 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 497 insertions(+), 0 deletions(-)
diff --git a/include/linux/lsm_audit.h b/include/linux/lsm_audit.h
new file mode 100644
index 0000000..e461b2c
--- /dev/null
+++ b/include/linux/lsm_audit.h
@@ -0,0 +1,111 @@
+/*
+ * Common LSM logging functions
+ * Heavily borrowed from selinux/avc.h
+ *
+ * Author : Etienne BASSET <etienne.basset(a)ensta.org>
+ *
+ * All credits to : Stephen Smalley, <sds(a)epoch.ncsc.mil>
+ * All BUGS to : Etienne BASSET <etienne.basset(a)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
index 0000000..b47a933
--- /dev/null
+++ b/security/lsm_audit.c
@@ -0,0 +1,386 @@
+/*
+ * common LSM auditing functions
+ *
+ * Based on code written for SELinux by :
+ * Stephen Smalley, <sds(a)epoch.ncsc.mil>
+ * James Morris <jmorris(a)redhat.com>
+ * Author : Etienne Basset, <etienne.basset(a)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);
+}