Re: [PATCH 1/2] security/smack implement logging V2

[Eric Paris <eparis@redhat.com>]

On Sun, 2009-04-05 at 10:47 +0200, Etienne Basset wrote:
> 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>
> ---
> diff --git a/include/linux/lsm_audit.h b/include/linux/lsm_audit.h
> new file mode 100644
> index 0000000..df54ad6
> --- /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@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 <asm/system.h>

I believe they say to always put asm/ after all linux/

> +#include <linux/key.h>
> +#include <linux/skbuff.h>
> +
> +
> +/* Auxiliary data to use in generating the audit record. */
> +struct common_audit_data {
> +	char    type;
> +#define AVC_AUDIT_DATA_FS      1
> +#define AVC_AUDIT_DATA_NET     2
> +#define AVC_AUDIT_DATA_CAP     3
> +#define AVC_AUDIT_DATA_IPC     4
> +#define AVC_AUDIT_DATA_TASK    5
> +#define AVC_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 {
> +			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 AVC audit data structure. */
> +#define COMMON_AUDIT_DATA_INIT(_d, _t) \
> +	{ memset((_d), 0, sizeof(struct common_audit_data)); \
> +	 (_d)->type = AVC_AUDIT_DATA_##_t; (_d)->function = __func__; }
> +
> +void common_lsm_audit(struct common_audit_data *a);
> +
> +#endif
> diff --git a/security/Makefile b/security/Makefile
> index fa77021..bd208b8 100644
> --- a/security/Makefile
> +++ b/security/Makefile
> @@ -15,7 +15,7 @@ obj-$(CONFIG_SECURITY)			+= security.o capability.o
>  obj-$(CONFIG_SECURITYFS)		+= inode.o
>  # Must precede capability.o in order to stack properly.
>  obj-$(CONFIG_SECURITY_SELINUX)		+= selinux/built-in.o
> -obj-$(CONFIG_SECURITY_SMACK)		+= smack/built-in.o
> +obj-$(CONFIG_SECURITY_SMACK)		+= smack/built-in.o lsm_audit.o
>  obj-$(CONFIG_SECURITY_TOMOYO)		+= tomoyo/built-in.o
>  obj-$(CONFIG_SECURITY_ROOTPLUG)		+= root_plug.o
>  obj-$(CONFIG_CGROUP_DEVICE)		+= device_cgroup.o
> diff --git a/security/lsm_audit.c b/security/lsm_audit.c
> new file mode 100644
> index 0000000..9056848
> --- /dev/null
> +++ b/security/lsm_audit.c
> @@ -0,0 +1,390 @@
> +/*
> + * 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 avc_print_ipv6_addr(struct audit_buffer *ab,
> +			struct in6_addr *addr, __be16 port,
> +			char *name1, char *name2)

avc_ is an SELinux'ism that doesn't make much sense.  I'm fine with just
print_ipv6_addr or audit_ipv6_addr or output_ipv6_addr....   

> +{
> +	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 avc_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)

odd place for a "\t "    if you aren't going to line up the arguments,
just use tabs.  Couple other "\t " oddities...