// SPDX-License-Identifier: GPL-2.0-only
/*
 * common LSM auditing functions
 *
 * Based on code written for SELinux by :
 *                      Stephen Smalley
 *                      James Morris <jmorris@redhat.com>
 * Author : Etienne Basset, <etienne.basset@ensta.org>
 */

#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/sctp.h>
#include <linux/lsm_audit.h>
#include <linux/security.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);
        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);

                ad->u.net->sport = th->source;
                ad->u.net->dport = th->dest;
                break;
        }
        case IPPROTO_UDP: {
                struct udphdr *uh = udp_hdr(skb);

                ad->u.net->sport = uh->source;
                ad->u.net->dport = uh->dest;
                break;
        }
        case IPPROTO_SCTP: {
                struct sctphdr *sh = sctp_hdr(skb);

                ad->u.net->sport = sh->source;
                ad->u.net->dport = sh->dest;
                break;
        }
        default:
                ret = -EINVAL;
        }
        return ret;
}
#if IS_ENABLED(CONFIG_IPV6)
/**
 * 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);
        ad->u.net->v6info.saddr = ip6->saddr;
        ad->u.net->v6info.daddr = ip6->daddr;
        /* 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_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,
                                   const struct in6_addr *addr, __be16 port,
                                   const char *name1, const 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, const char *name1, const char *name2)
{
        if (addr)
                audit_log_format(ab, " %s=%pI4", name1, &addr);
        if (port)
                audit_log_format(ab, " %s=%d", name2, ntohs(port));
}

/**
 * audit_log_lsm_data - helper to log common LSM audit data
 * @ab : the audit buffer
 * @a : common audit data
 */
void audit_log_lsm_data(struct audit_buffer *ab,
                        const struct common_audit_data *a)
{
        /*
         * To keep stack sizes in check force programmers 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);

        switch (a->type) {
        case LSM_AUDIT_DATA_NONE:
                return;
        case LSM_AUDIT_DATA_IPC:
                audit_log_format(ab, " ipc_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 = d_backing_inode(a->u.path.dentry);
                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_FILE: {
                struct inode *inode;

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

                inode = file_inode(a->u.file);
                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_IOCTL_OP: {
                struct inode *inode;

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

                inode = a->u.op->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);
                }

                audit_log_format(ab, " ioctlcmd=0x%hx", a->u.op->cmd);
                break;
        }
        case LSM_AUDIT_DATA_DENTRY: {
                struct inode *inode;

                audit_log_format(ab, " name=");
                spin_lock(&a->u.dentry->d_lock);
                audit_log_untrustedstring(ab, a->u.dentry->d_name.name);
                spin_unlock(&a->u.dentry->d_lock);

                inode = d_backing_inode(a->u.dentry);
                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;

                rcu_read_lock();
                inode = a->u.inode;
                dentry = d_find_alias_rcu(inode);
                if (dentry) {
                        audit_log_format(ab, " name=");
                        spin_lock(&dentry->d_lock);
                        audit_log_untrustedstring(ab, dentry->d_name.name);
                        spin_unlock(&dentry->d_lock);
                }
                audit_log_format(ab, " dev=");
                audit_log_untrustedstring(ab, inode->i_sb->s_id);
                audit_log_format(ab, " ino=%lu", inode->i_ino);
                rcu_read_unlock();
                break;
        }
        case LSM_AUDIT_DATA_TASK: {
                struct task_struct *tsk = a->u.tsk;
                if (tsk) {
                        pid_t pid = task_tgid_nr(tsk);
                        if (pid) {
                                char tskcomm[sizeof(tsk->comm)];
                                audit_log_format(ab, " opid=%d ocomm=", pid);
                                audit_log_untrustedstring(ab,
                                    get_task_comm(tskcomm, tsk));
                        }
                }
                break;
        }
        case LSM_AUDIT_DATA_NET:
                if (a->u.net->sk) {
                        const struct sock *sk = a->u.net->sk;
                        const struct unix_sock *u;
                        struct unix_address *addr;
                        int len = 0;
                        char *p = NULL;

                        switch (sk->sk_family) {
                        case AF_INET: {
                                const 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: {
                                const 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);
                                addr = smp_load_acquire(&u->addr);
                                if (!addr)
                                        break;
                                if (u->path.dentry) {
                                        audit_log_d_path(ab, " path=", &u->path);
                                        break;
                                }
                                len = addr->len-sizeof(short);
                                p = &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;
        case LSM_AUDIT_DATA_IBPKEY: {
                struct in6_addr sbn_pfx;

                memset(&sbn_pfx.s6_addr, 0,
                       sizeof(sbn_pfx.s6_addr));
                memcpy(&sbn_pfx.s6_addr, &a->u.ibpkey->subnet_prefix,
                       sizeof(a->u.ibpkey->subnet_prefix));
                audit_log_format(ab, " pkey=0x%x subnet_prefix=%pI6c",
                                 a->u.ibpkey->pkey, &sbn_pfx);
                break;
        }
        case LSM_AUDIT_DATA_IBENDPORT:
                audit_log_format(ab, " device=%s port_num=%u",
                                 a->u.ibendport->dev_name,
                                 a->u.ibendport->port);
                break;
        case LSM_AUDIT_DATA_LOCKDOWN:
                audit_log_format(ab, " lockdown_reason=\"%s\"",
                                 lockdown_reasons[a->u.reason]);
                break;
        case LSM_AUDIT_DATA_ANONINODE:
                audit_log_format(ab, " anonclass=%s", a->u.anonclass);
                break;
        case LSM_AUDIT_DATA_NLMSGTYPE:
                audit_log_format(ab, " nl-msgtype=%hu", a->u.nlmsg_type);
                break;
        } /* switch (a->type) */
}

/**
 * dump_common_audit_data - helper to dump common audit data
 * @ab : the audit buffer
 * @a : common audit data
 */
static void dump_common_audit_data(struct audit_buffer *ab,
                                   const struct common_audit_data *a)
{
        char comm[sizeof(current->comm)];

        audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
        audit_log_untrustedstring(ab, get_task_comm(comm, current));
        audit_log_lsm_data(ab, a);
}

/**
 * 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(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);
}