diff options
Diffstat (limited to 'kernel/audit.c')
| -rw-r--r-- | kernel/audit.c | 2036 |
1 files changed, 2036 insertions, 0 deletions
diff --git a/kernel/audit.c b/kernel/audit.c new file mode 100644 index 000000000..1c13e4267 --- /dev/null +++ b/kernel/audit.c @@ -0,0 +1,2036 @@ +/* audit.c -- Auditing support + * Gateway between the kernel (e.g., selinux) and the user-space audit daemon. + * System-call specific features have moved to auditsc.c + * + * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina. + * All Rights Reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + * Written by Rickard E. (Rik) Faith <faith@redhat.com> + * + * Goals: 1) Integrate fully with Security Modules. + * 2) Minimal run-time overhead: + * a) Minimal when syscall auditing is disabled (audit_enable=0). + * b) Small when syscall auditing is enabled and no audit record + * is generated (defer as much work as possible to record + * generation time): + * i) context is allocated, + * ii) names from getname are stored without a copy, and + * iii) inode information stored from path_lookup. + * 3) Ability to disable syscall auditing at boot time (audit=0). + * 4) Usable by other parts of the kernel (if audit_log* is called, + * then a syscall record will be generated automatically for the + * current syscall). + * 5) Netlink interface to user-space. + * 6) Support low-overhead kernel-based filtering to minimize the + * information that must be passed to user-space. + * + * Example user-space utilities: http://people.redhat.com/sgrubb/audit/ + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/file.h> +#include <linux/init.h> +#include <linux/types.h> +#include <linux/atomic.h> +#include <linux/mm.h> +#include <linux/export.h> +#include <linux/slab.h> +#include <linux/err.h> +#include <linux/kthread.h> +#include <linux/kernel.h> +#include <linux/syscalls.h> + +#include <linux/audit.h> + +#include <net/sock.h> +#include <net/netlink.h> +#include <linux/skbuff.h> +#ifdef CONFIG_SECURITY +#include <linux/security.h> +#endif +#include <linux/freezer.h> +#include <linux/tty.h> +#include <linux/pid_namespace.h> +#include <net/netns/generic.h> + +#include "audit.h" + +/* No auditing will take place until audit_initialized == AUDIT_INITIALIZED. + * (Initialization happens after skb_init is called.) */ +#define AUDIT_DISABLED -1 +#define AUDIT_UNINITIALIZED 0 +#define AUDIT_INITIALIZED 1 +static int audit_initialized; + +#define AUDIT_OFF 0 +#define AUDIT_ON 1 +#define AUDIT_LOCKED 2 +u32 audit_enabled; +u32 audit_ever_enabled; + +EXPORT_SYMBOL_GPL(audit_enabled); + +/* Default state when kernel boots without any parameters. */ +static u32 audit_default; + +/* If auditing cannot proceed, audit_failure selects what happens. */ +static u32 audit_failure = AUDIT_FAIL_PRINTK; + +/* + * If audit records are to be written to the netlink socket, audit_pid + * contains the pid of the auditd process and audit_nlk_portid contains + * the portid to use to send netlink messages to that process. + */ +int audit_pid; +static __u32 audit_nlk_portid; + +/* If audit_rate_limit is non-zero, limit the rate of sending audit records + * to that number per second. This prevents DoS attacks, but results in + * audit records being dropped. */ +static u32 audit_rate_limit; + +/* Number of outstanding audit_buffers allowed. + * When set to zero, this means unlimited. */ +static u32 audit_backlog_limit = 64; +#define AUDIT_BACKLOG_WAIT_TIME (60 * HZ) +static u32 audit_backlog_wait_time_master = AUDIT_BACKLOG_WAIT_TIME; +static u32 audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME; +static u32 audit_backlog_wait_overflow = 0; + +/* The identity of the user shutting down the audit system. */ +kuid_t audit_sig_uid = INVALID_UID; +pid_t audit_sig_pid = -1; +u32 audit_sig_sid = 0; + +/* Records can be lost in several ways: + 0) [suppressed in audit_alloc] + 1) out of memory in audit_log_start [kmalloc of struct audit_buffer] + 2) out of memory in audit_log_move [alloc_skb] + 3) suppressed due to audit_rate_limit + 4) suppressed due to audit_backlog_limit +*/ +static atomic_t audit_lost = ATOMIC_INIT(0); + +/* The netlink socket. */ +static struct sock *audit_sock; +static int audit_net_id; + +/* Hash for inode-based rules */ +struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS]; + +/* The audit_freelist is a list of pre-allocated audit buffers (if more + * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of + * being placed on the freelist). */ +static DEFINE_SPINLOCK(audit_freelist_lock); +static int audit_freelist_count; +static LIST_HEAD(audit_freelist); + +static struct sk_buff_head audit_skb_queue; +/* queue of skbs to send to auditd when/if it comes back */ +static struct sk_buff_head audit_skb_hold_queue; +static struct task_struct *kauditd_task; +static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait); +static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait); + +static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION, + .mask = -1, + .features = 0, + .lock = 0,}; + +static char *audit_feature_names[2] = { + "only_unset_loginuid", + "loginuid_immutable", +}; + + +/* Serialize requests from userspace. */ +DEFINE_MUTEX(audit_cmd_mutex); + +/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting + * audit records. Since printk uses a 1024 byte buffer, this buffer + * should be at least that large. */ +#define AUDIT_BUFSIZ 1024 + +/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the + * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ +#define AUDIT_MAXFREE (2*NR_CPUS) + +/* The audit_buffer is used when formatting an audit record. The caller + * locks briefly to get the record off the freelist or to allocate the + * buffer, and locks briefly to send the buffer to the netlink layer or + * to place it on a transmit queue. Multiple audit_buffers can be in + * use simultaneously. */ +struct audit_buffer { + struct list_head list; + struct sk_buff *skb; /* formatted skb ready to send */ + struct audit_context *ctx; /* NULL or associated context */ + gfp_t gfp_mask; +}; + +struct audit_reply { + __u32 portid; + struct net *net; + struct sk_buff *skb; +}; + +static void audit_set_portid(struct audit_buffer *ab, __u32 portid) +{ + if (ab) { + struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); + nlh->nlmsg_pid = portid; + } +} + +void audit_panic(const char *message) +{ + switch (audit_failure) { + case AUDIT_FAIL_SILENT: + break; + case AUDIT_FAIL_PRINTK: + if (printk_ratelimit()) + pr_err("%s\n", message); + break; + case AUDIT_FAIL_PANIC: + /* test audit_pid since printk is always losey, why bother? */ + if (audit_pid) + panic("audit: %s\n", message); + break; + } +} + +static inline int audit_rate_check(void) +{ + static unsigned long last_check = 0; + static int messages = 0; + static DEFINE_SPINLOCK(lock); + unsigned long flags; + unsigned long now; + unsigned long elapsed; + int retval = 0; + + if (!audit_rate_limit) return 1; + + spin_lock_irqsave(&lock, flags); + if (++messages < audit_rate_limit) { + retval = 1; + } else { + now = jiffies; + elapsed = now - last_check; + if (elapsed > HZ) { + last_check = now; + messages = 0; + retval = 1; + } + } + spin_unlock_irqrestore(&lock, flags); + + return retval; +} + +/** + * audit_log_lost - conditionally log lost audit message event + * @message: the message stating reason for lost audit message + * + * Emit at least 1 message per second, even if audit_rate_check is + * throttling. + * Always increment the lost messages counter. +*/ +void audit_log_lost(const char *message) +{ + static unsigned long last_msg = 0; + static DEFINE_SPINLOCK(lock); + unsigned long flags; + unsigned long now; + int print; + + atomic_inc(&audit_lost); + + print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); + + if (!print) { + spin_lock_irqsave(&lock, flags); + now = jiffies; + if (now - last_msg > HZ) { + print = 1; + last_msg = now; + } + spin_unlock_irqrestore(&lock, flags); + } + + if (print) { + if (printk_ratelimit()) + pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n", + atomic_read(&audit_lost), + audit_rate_limit, + audit_backlog_limit); + audit_panic(message); + } +} + +static int audit_log_config_change(char *function_name, u32 new, u32 old, + int allow_changes) +{ + struct audit_buffer *ab; + int rc = 0; + + ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE); + if (unlikely(!ab)) + return rc; + audit_log_format(ab, "%s=%u old=%u", function_name, new, old); + audit_log_session_info(ab); + rc = audit_log_task_context(ab); + if (rc) + allow_changes = 0; /* Something weird, deny request */ + audit_log_format(ab, " res=%d", allow_changes); + audit_log_end(ab); + return rc; +} + +static int audit_do_config_change(char *function_name, u32 *to_change, u32 new) +{ + int allow_changes, rc = 0; + u32 old = *to_change; + + /* check if we are locked */ + if (audit_enabled == AUDIT_LOCKED) + allow_changes = 0; + else + allow_changes = 1; + + if (audit_enabled != AUDIT_OFF) { + rc = audit_log_config_change(function_name, new, old, allow_changes); + if (rc) + allow_changes = 0; + } + + /* If we are allowed, make the change */ + if (allow_changes == 1) + *to_change = new; + /* Not allowed, update reason */ + else if (rc == 0) + rc = -EPERM; + return rc; +} + +static int audit_set_rate_limit(u32 limit) +{ + return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit); +} + +static int audit_set_backlog_limit(u32 limit) +{ + return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit); +} + +static int audit_set_backlog_wait_time(u32 timeout) +{ + return audit_do_config_change("audit_backlog_wait_time", + &audit_backlog_wait_time_master, timeout); +} + +static int audit_set_enabled(u32 state) +{ + int rc; + if (state > AUDIT_LOCKED) + return -EINVAL; + + rc = audit_do_config_change("audit_enabled", &audit_enabled, state); + if (!rc) + audit_ever_enabled |= !!state; + + return rc; +} + +static int audit_set_failure(u32 state) +{ + if (state != AUDIT_FAIL_SILENT + && state != AUDIT_FAIL_PRINTK + && state != AUDIT_FAIL_PANIC) + return -EINVAL; + + return audit_do_config_change("audit_failure", &audit_failure, state); +} + +/* + * Queue skbs to be sent to auditd when/if it comes back. These skbs should + * already have been sent via prink/syslog and so if these messages are dropped + * it is not a huge concern since we already passed the audit_log_lost() + * notification and stuff. This is just nice to get audit messages during + * boot before auditd is running or messages generated while auditd is stopped. + * This only holds messages is audit_default is set, aka booting with audit=1 + * or building your kernel that way. + */ +static void audit_hold_skb(struct sk_buff *skb) +{ + if (audit_default && + (!audit_backlog_limit || + skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)) + skb_queue_tail(&audit_skb_hold_queue, skb); + else + kfree_skb(skb); +} + +/* + * For one reason or another this nlh isn't getting delivered to the userspace + * audit daemon, just send it to printk. + */ +static void audit_printk_skb(struct sk_buff *skb) +{ + struct nlmsghdr *nlh = nlmsg_hdr(skb); + char *data = nlmsg_data(nlh); + + if (nlh->nlmsg_type != AUDIT_EOE) { + if (printk_ratelimit()) + pr_notice("type=%d %s\n", nlh->nlmsg_type, data); + else + audit_log_lost("printk limit exceeded"); + } + + audit_hold_skb(skb); +} + +static void kauditd_send_skb(struct sk_buff *skb) +{ + int err; + /* take a reference in case we can't send it and we want to hold it */ + skb_get(skb); + err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0); + if (err < 0) { + BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */ + if (audit_pid) { + pr_err("*NO* daemon at audit_pid=%d\n", audit_pid); + audit_log_lost("auditd disappeared"); + audit_pid = 0; + audit_sock = NULL; + } + /* we might get lucky and get this in the next auditd */ + audit_hold_skb(skb); + } else + /* drop the extra reference if sent ok */ + consume_skb(skb); +} + +/* + * kauditd_send_multicast_skb - send the skb to multicast userspace listeners + * + * This function doesn't consume an skb as might be expected since it has to + * copy it anyways. + */ +static void kauditd_send_multicast_skb(struct sk_buff *skb, gfp_t gfp_mask) +{ + struct sk_buff *copy; + struct audit_net *aunet = net_generic(&init_net, audit_net_id); + struct sock *sock = aunet->nlsk; + + if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG)) + return; + + /* + * The seemingly wasteful skb_copy() rather than bumping the refcount + * using skb_get() is necessary because non-standard mods are made to + * the skb by the original kaudit unicast socket send routine. The + * existing auditd daemon assumes this breakage. Fixing this would + * require co-ordinating a change in the established protocol between + * the kaudit kernel subsystem and the auditd userspace code. There is + * no reason for new multicast clients to continue with this + * non-compliance. + */ + copy = skb_copy(skb, gfp_mask); + if (!copy) + return; + + nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, gfp_mask); +} + +/* + * flush_hold_queue - empty the hold queue if auditd appears + * + * If auditd just started, drain the queue of messages already + * sent to syslog/printk. Remember loss here is ok. We already + * called audit_log_lost() if it didn't go out normally. so the + * race between the skb_dequeue and the next check for audit_pid + * doesn't matter. + * + * If you ever find kauditd to be too slow we can get a perf win + * by doing our own locking and keeping better track if there + * are messages in this queue. I don't see the need now, but + * in 5 years when I want to play with this again I'll see this + * note and still have no friggin idea what i'm thinking today. + */ +static void flush_hold_queue(void) +{ + struct sk_buff *skb; + + if (!audit_default || !audit_pid) + return; + + skb = skb_dequeue(&audit_skb_hold_queue); + if (likely(!skb)) + return; + + while (skb && audit_pid) { + kauditd_send_skb(skb); + skb = skb_dequeue(&audit_skb_hold_queue); + } + + /* + * if auditd just disappeared but we + * dequeued an skb we need to drop ref + */ + if (skb) + consume_skb(skb); +} + +static int kauditd_thread(void *dummy) +{ + set_freezable(); + while (!kthread_should_stop()) { + struct sk_buff *skb; + + flush_hold_queue(); + + skb = skb_dequeue(&audit_skb_queue); + + if (skb) { + if (skb_queue_len(&audit_skb_queue) <= audit_backlog_limit) + wake_up(&audit_backlog_wait); + if (audit_pid) + kauditd_send_skb(skb); + else + audit_printk_skb(skb); + continue; + } + + wait_event_freezable(kauditd_wait, skb_queue_len(&audit_skb_queue)); + } + return 0; +} + +int audit_send_list(void *_dest) +{ + struct audit_netlink_list *dest = _dest; + struct sk_buff *skb; + struct net *net = dest->net; + struct audit_net *aunet = net_generic(net, audit_net_id); + + /* wait for parent to finish and send an ACK */ + mutex_lock(&audit_cmd_mutex); + mutex_unlock(&audit_cmd_mutex); + + while ((skb = __skb_dequeue(&dest->q)) != NULL) + netlink_unicast(aunet->nlsk, skb, dest->portid, 0); + + put_net(net); + kfree(dest); + + return 0; +} + +struct sk_buff *audit_make_reply(__u32 portid, int seq, int type, int done, + int multi, const void *payload, int size) +{ + struct sk_buff *skb; + struct nlmsghdr *nlh; + void *data; + int flags = multi ? NLM_F_MULTI : 0; + int t = done ? NLMSG_DONE : type; + + skb = nlmsg_new(size, GFP_KERNEL); + if (!skb) + return NULL; + + nlh = nlmsg_put(skb, portid, seq, t, size, flags); + if (!nlh) + goto out_kfree_skb; + data = nlmsg_data(nlh); + memcpy(data, payload, size); + return skb; + +out_kfree_skb: + kfree_skb(skb); + return NULL; +} + +static int audit_send_reply_thread(void *arg) +{ + struct audit_reply *reply = (struct audit_reply *)arg; + struct net *net = reply->net; + struct audit_net *aunet = net_generic(net, audit_net_id); + + mutex_lock(&audit_cmd_mutex); + mutex_unlock(&audit_cmd_mutex); + + /* Ignore failure. It'll only happen if the sender goes away, + because our timeout is set to infinite. */ + netlink_unicast(aunet->nlsk , reply->skb, reply->portid, 0); + put_net(net); + kfree(reply); + return 0; +} +/** + * audit_send_reply - send an audit reply message via netlink + * @request_skb: skb of request we are replying to (used to target the reply) + * @seq: sequence number + * @type: audit message type + * @done: done (last) flag + * @multi: multi-part message flag + * @payload: payload data + * @size: payload size + * + * Allocates an skb, builds the netlink message, and sends it to the port id. + * No failure notifications. + */ +static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done, + int multi, const void *payload, int size) +{ + u32 portid = NETLINK_CB(request_skb).portid; + struct net *net = sock_net(NETLINK_CB(request_skb).sk); + struct sk_buff *skb; + struct task_struct *tsk; + struct audit_reply *reply = kmalloc(sizeof(struct audit_reply), + GFP_KERNEL); + + if (!reply) + return; + + skb = audit_make_reply(portid, seq, type, done, multi, payload, size); + if (!skb) + goto out; + + reply->net = get_net(net); + reply->portid = portid; + reply->skb = skb; + + tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply"); + if (!IS_ERR(tsk)) + return; + kfree_skb(skb); +out: + kfree(reply); +} + +/* + * Check for appropriate CAP_AUDIT_ capabilities on incoming audit + * control messages. + */ +static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type) +{ + int err = 0; + + /* Only support initial user namespace for now. */ + /* + * We return ECONNREFUSED because it tricks userspace into thinking + * that audit was not configured into the kernel. Lots of users + * configure their PAM stack (because that's what the distro does) + * to reject login if unable to send messages to audit. If we return + * ECONNREFUSED the PAM stack thinks the kernel does not have audit + * configured in and will let login proceed. If we return EPERM + * userspace will reject all logins. This should be removed when we + * support non init namespaces!! + */ + if (current_user_ns() != &init_user_ns) + return -ECONNREFUSED; + + switch (msg_type) { + case AUDIT_LIST: + case AUDIT_ADD: + case AUDIT_DEL: + return -EOPNOTSUPP; + case AUDIT_GET: + case AUDIT_SET: + case AUDIT_GET_FEATURE: + case AUDIT_SET_FEATURE: + case AUDIT_LIST_RULES: + case AUDIT_ADD_RULE: + case AUDIT_DEL_RULE: + case AUDIT_SIGNAL_INFO: + case AUDIT_TTY_GET: + case AUDIT_TTY_SET: + case AUDIT_TRIM: + case AUDIT_MAKE_EQUIV: + /* Only support auditd and auditctl in initial pid namespace + * for now. */ + if (task_active_pid_ns(current) != &init_pid_ns) + return -EPERM; + + if (!netlink_capable(skb, CAP_AUDIT_CONTROL)) + err = -EPERM; + break; + case AUDIT_USER: + case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: + case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: + if (!netlink_capable(skb, CAP_AUDIT_WRITE)) + err = -EPERM; + break; + default: /* bad msg */ + err = -EINVAL; + } + + return err; +} + +static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type) +{ + int rc = 0; + uid_t uid = from_kuid(&init_user_ns, current_uid()); + pid_t pid = task_tgid_nr(current); + + if (!audit_enabled && msg_type != AUDIT_USER_AVC) { + *ab = NULL; + return rc; + } + + *ab = audit_log_start(NULL, GFP_KERNEL, msg_type); + if (unlikely(!*ab)) + return rc; + audit_log_format(*ab, "pid=%d uid=%u", pid, uid); + audit_log_session_info(*ab); + audit_log_task_context(*ab); + + return rc; +} + +int is_audit_feature_set(int i) +{ + return af.features & AUDIT_FEATURE_TO_MASK(i); +} + + +static int audit_get_feature(struct sk_buff *skb) +{ + u32 seq; + + seq = nlmsg_hdr(skb)->nlmsg_seq; + + audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af)); + + return 0; +} + +static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature, + u32 old_lock, u32 new_lock, int res) +{ + struct audit_buffer *ab; + + if (audit_enabled == AUDIT_OFF) + return; + + ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_FEATURE_CHANGE); + audit_log_task_info(ab, current); + audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d", + audit_feature_names[which], !!old_feature, !!new_feature, + !!old_lock, !!new_lock, res); + audit_log_end(ab); +} + +static int audit_set_feature(struct sk_buff *skb) +{ + struct audit_features *uaf; + int i; + + BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names)); + uaf = nlmsg_data(nlmsg_hdr(skb)); + + /* if there is ever a version 2 we should handle that here */ + + for (i = 0; i <= AUDIT_LAST_FEATURE; i++) { + u32 feature = AUDIT_FEATURE_TO_MASK(i); + u32 old_feature, new_feature, old_lock, new_lock; + + /* if we are not changing this feature, move along */ + if (!(feature & uaf->mask)) + continue; + + old_feature = af.features & feature; + new_feature = uaf->features & feature; + new_lock = (uaf->lock | af.lock) & feature; + old_lock = af.lock & feature; + + /* are we changing a locked feature? */ + if (old_lock && (new_feature != old_feature)) { + audit_log_feature_change(i, old_feature, new_feature, + old_lock, new_lock, 0); + return -EPERM; + } + } + /* nothing invalid, do the changes */ + for (i = 0; i <= AUDIT_LAST_FEATURE; i++) { + u32 feature = AUDIT_FEATURE_TO_MASK(i); + u32 old_feature, new_feature, old_lock, new_lock; + + /* if we are not changing this feature, move along */ + if (!(feature & uaf->mask)) + continue; + + old_feature = af.features & feature; + new_feature = uaf->features & feature; + old_lock = af.lock & feature; + new_lock = (uaf->lock | af.lock) & feature; + + if (new_feature != old_feature) + audit_log_feature_change(i, old_feature, new_feature, + old_lock, new_lock, 1); + + if (new_feature) + af.features |= feature; + else + af.features &= ~feature; + af.lock |= new_lock; + } + + return 0; +} + +static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) +{ + u32 seq; + void *data; + int err; + struct audit_buffer *ab; + u16 msg_type = nlh->nlmsg_type; + struct audit_sig_info *sig_data; + char *ctx = NULL; + u32 len; + + err = audit_netlink_ok(skb, msg_type); + if (err) + return err; + + /* As soon as there's any sign of userspace auditd, + * start kauditd to talk to it */ + if (!kauditd_task) { + kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd"); + if (IS_ERR(kauditd_task)) { + err = PTR_ERR(kauditd_task); + kauditd_task = NULL; + return err; + } + } + seq = nlh->nlmsg_seq; + data = nlmsg_data(nlh); + + switch (msg_type) { + case AUDIT_GET: { + struct audit_status s; + memset(&s, 0, sizeof(s)); + s.enabled = audit_enabled; + s.failure = audit_failure; + s.pid = audit_pid; + s.rate_limit = audit_rate_limit; + s.backlog_limit = audit_backlog_limit; + s.lost = atomic_read(&audit_lost); + s.backlog = skb_queue_len(&audit_skb_queue); + s.feature_bitmap = AUDIT_FEATURE_BITMAP_ALL; + s.backlog_wait_time = audit_backlog_wait_time_master; + audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s)); + break; + } + case AUDIT_SET: { + struct audit_status s; + memset(&s, 0, sizeof(s)); + /* guard against past and future API changes */ + memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh))); + if (s.mask & AUDIT_STATUS_ENABLED) { + err = audit_set_enabled(s.enabled); + if (err < 0) + return err; + } + if (s.mask & AUDIT_STATUS_FAILURE) { + err = audit_set_failure(s.failure); + if (err < 0) + return err; + } + if (s.mask & AUDIT_STATUS_PID) { + int new_pid = s.pid; + + if ((!new_pid) && (task_tgid_vnr(current) != audit_pid)) + return -EACCES; + if (audit_enabled != AUDIT_OFF) + audit_log_config_change("audit_pid", new_pid, audit_pid, 1); + audit_pid = new_pid; + audit_nlk_portid = NETLINK_CB(skb).portid; + audit_sock = skb->sk; + } + if (s.mask & AUDIT_STATUS_RATE_LIMIT) { + err = audit_set_rate_limit(s.rate_limit); + if (err < 0) + return err; + } + if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) { + err = audit_set_backlog_limit(s.backlog_limit); + if (err < 0) + return err; + } + if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) { + if (sizeof(s) > (size_t)nlh->nlmsg_len) + return -EINVAL; + if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME) + return -EINVAL; + err = audit_set_backlog_wait_time(s.backlog_wait_time); + if (err < 0) + return err; + } + break; + } + case AUDIT_GET_FEATURE: + err = audit_get_feature(skb); + if (err) + return err; + break; + case AUDIT_SET_FEATURE: + err = audit_set_feature(skb); + if (err) + return err; + break; + case AUDIT_USER: + case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: + case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: + if (!audit_enabled && msg_type != AUDIT_USER_AVC) + return 0; + + err = audit_filter_user(msg_type); + if (err == 1) { /* match or error */ + err = 0; + if (msg_type == AUDIT_USER_TTY) { + err = tty_audit_push_current(); + if (err) + break; + } + mutex_unlock(&audit_cmd_mutex); + audit_log_common_recv_msg(&ab, msg_type); + if (msg_type != AUDIT_USER_TTY) + audit_log_format(ab, " msg='%.*s'", + AUDIT_MESSAGE_TEXT_MAX, + (char *)data); + else { + int size; + + audit_log_format(ab, " data="); + size = nlmsg_len(nlh); + if (size > 0 && + ((unsigned char *)data)[size - 1] == '\0') + size--; + audit_log_n_untrustedstring(ab, data, size); + } + audit_set_portid(ab, NETLINK_CB(skb).portid); + audit_log_end(ab); + mutex_lock(&audit_cmd_mutex); + } + break; + case AUDIT_ADD_RULE: + case AUDIT_DEL_RULE: + if (nlmsg_len(nlh) < sizeof(struct audit_rule_data)) + return -EINVAL; + if (audit_enabled == AUDIT_LOCKED) { + audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE); + audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled); + audit_log_end(ab); + return -EPERM; + } + err = audit_rule_change(msg_type, NETLINK_CB(skb).portid, + seq, data, nlmsg_len(nlh)); + break; + case AUDIT_LIST_RULES: + err = audit_list_rules_send(skb, seq); + break; + case AUDIT_TRIM: + audit_trim_trees(); + audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE); + audit_log_format(ab, " op=trim res=1"); + audit_log_end(ab); + break; + case AUDIT_MAKE_EQUIV: { + void *bufp = data; + u32 sizes[2]; + size_t msglen = nlmsg_len(nlh); + char *old, *new; + + err = -EINVAL; + if (msglen < 2 * sizeof(u32)) + break; + memcpy(sizes, bufp, 2 * sizeof(u32)); + bufp += 2 * sizeof(u32); + msglen -= 2 * sizeof(u32); + old = audit_unpack_string(&bufp, &msglen, sizes[0]); + if (IS_ERR(old)) { + err = PTR_ERR(old); + break; + } + new = audit_unpack_string(&bufp, &msglen, sizes[1]); + if (IS_ERR(new)) { + err = PTR_ERR(new); + kfree(old); + break; + } + /* OK, here comes... */ + err = audit_tag_tree(old, new); + + audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE); + + audit_log_format(ab, " op=make_equiv old="); + audit_log_untrustedstring(ab, old); + audit_log_format(ab, " new="); + audit_log_untrustedstring(ab, new); + audit_log_format(ab, " res=%d", !err); + audit_log_end(ab); + kfree(old); + kfree(new); + break; + } + case AUDIT_SIGNAL_INFO: + len = 0; + if (audit_sig_sid) { + err = security_secid_to_secctx(audit_sig_sid, &ctx, &len); + if (err) + return err; + } + sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL); + if (!sig_data) { + if (audit_sig_sid) + security_release_secctx(ctx, len); + return -ENOMEM; + } + sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid); + sig_data->pid = audit_sig_pid; + if (audit_sig_sid) { + memcpy(sig_data->ctx, ctx, len); + security_release_secctx(ctx, len); + } + audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0, + sig_data, sizeof(*sig_data) + len); + kfree(sig_data); + break; + case AUDIT_TTY_GET: { + struct audit_tty_status s; + struct task_struct *tsk = current; + + spin_lock(&tsk->sighand->siglock); + s.enabled = tsk->signal->audit_tty; + s.log_passwd = tsk->signal->audit_tty_log_passwd; + spin_unlock(&tsk->sighand->siglock); + + audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s)); + break; + } + case AUDIT_TTY_SET: { + struct audit_tty_status s, old; + struct task_struct *tsk = current; + struct audit_buffer *ab; + + memset(&s, 0, sizeof(s)); + /* guard against past and future API changes */ + memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh))); + /* check if new data is valid */ + if ((s.enabled != 0 && s.enabled != 1) || + (s.log_passwd != 0 && s.log_passwd != 1)) + err = -EINVAL; + + spin_lock(&tsk->sighand->siglock); + old.enabled = tsk->signal->audit_tty; + old.log_passwd = tsk->signal->audit_tty_log_passwd; + if (!err) { + tsk->signal->audit_tty = s.enabled; + tsk->signal->audit_tty_log_passwd = s.log_passwd; + } + spin_unlock(&tsk->sighand->siglock); + + audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE); + audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d" + " old-log_passwd=%d new-log_passwd=%d res=%d", + old.enabled, s.enabled, old.log_passwd, + s.log_passwd, !err); + audit_log_end(ab); + break; + } + default: + err = -EINVAL; + break; + } + + return err < 0 ? err : 0; +} + +/* + * Get message from skb. Each message is processed by audit_receive_msg. + * Malformed skbs with wrong length are discarded silently. + */ +static void audit_receive_skb(struct sk_buff *skb) +{ + struct nlmsghdr *nlh; + /* + * len MUST be signed for nlmsg_next to be able to dec it below 0 + * if the nlmsg_len was not aligned + */ + int len; + int err; + + nlh = nlmsg_hdr(skb); + len = skb->len; + + while (nlmsg_ok(nlh, len)) { + err = audit_receive_msg(skb, nlh); + /* if err or if this message says it wants a response */ + if (err || (nlh->nlmsg_flags & NLM_F_ACK)) + netlink_ack(skb, nlh, err); + + nlh = nlmsg_next(nlh, &len); + } +} + +/* Receive messages from netlink socket. */ +static void audit_receive(struct sk_buff *skb) +{ + mutex_lock(&audit_cmd_mutex); + audit_receive_skb(skb); + mutex_unlock(&audit_cmd_mutex); +} + +/* Run custom bind function on netlink socket group connect or bind requests. */ +static int audit_bind(struct net *net, int group) +{ + if (!capable(CAP_AUDIT_READ)) + return -EPERM; + + return 0; +} + +static int __net_init audit_net_init(struct net *net) +{ + struct netlink_kernel_cfg cfg = { + .input = audit_receive, + .bind = audit_bind, + .flags = NL_CFG_F_NONROOT_RECV, + .groups = AUDIT_NLGRP_MAX, + }; + + struct audit_net *aunet = net_generic(net, audit_net_id); + + aunet->nlsk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg); + if (aunet->nlsk == NULL) { + audit_panic("cannot initialize netlink socket in namespace"); + return -ENOMEM; + } + aunet->nlsk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT; + return 0; +} + +static void __net_exit audit_net_exit(struct net *net) +{ + struct audit_net *aunet = net_generic(net, audit_net_id); + struct sock *sock = aunet->nlsk; + if (sock == audit_sock) { + audit_pid = 0; + audit_sock = NULL; + } + + RCU_INIT_POINTER(aunet->nlsk, NULL); + synchronize_net(); + netlink_kernel_release(sock); +} + +static struct pernet_operations audit_net_ops __net_initdata = { + .init = audit_net_init, + .exit = audit_net_exit, + .id = &audit_net_id, + .size = sizeof(struct audit_net), +}; + +/* Initialize audit support at boot time. */ +static int __init audit_init(void) +{ + int i; + + if (audit_initialized == AUDIT_DISABLED) + return 0; + + pr_info("initializing netlink subsys (%s)\n", + audit_default ? "enabled" : "disabled"); + register_pernet_subsys(&audit_net_ops); + + skb_queue_head_init(&audit_skb_queue); + skb_queue_head_init(&audit_skb_hold_queue); + audit_initialized = AUDIT_INITIALIZED; + audit_enabled = audit_default; + audit_ever_enabled |= !!audit_default; + + audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized"); + + for (i = 0; i < AUDIT_INODE_BUCKETS; i++) + INIT_LIST_HEAD(&audit_inode_hash[i]); + + return 0; +} +__initcall(audit_init); + +/* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ +static int __init audit_enable(char *str) +{ + audit_default = !!simple_strtol(str, NULL, 0); + if (!audit_default) + audit_initialized = AUDIT_DISABLED; + + pr_info("%s\n", audit_default ? + "enabled (after initialization)" : "disabled (until reboot)"); + + return 1; +} +__setup("audit=", audit_enable); + +/* Process kernel command-line parameter at boot time. + * audit_backlog_limit=<n> */ +static int __init audit_backlog_limit_set(char *str) +{ + u32 audit_backlog_limit_arg; + + pr_info("audit_backlog_limit: "); + if (kstrtouint(str, 0, &audit_backlog_limit_arg)) { + pr_cont("using default of %u, unable to parse %s\n", + audit_backlog_limit, str); + return 1; + } + + audit_backlog_limit = audit_backlog_limit_arg; + pr_cont("%d\n", audit_backlog_limit); + + return 1; +} +__setup("audit_backlog_limit=", audit_backlog_limit_set); + +static void audit_buffer_free(struct audit_buffer *ab) +{ + unsigned long flags; + + if (!ab) + return; + + if (ab->skb) + kfree_skb(ab->skb); + + spin_lock_irqsave(&audit_freelist_lock, flags); + if (audit_freelist_count > AUDIT_MAXFREE) + kfree(ab); + else { + audit_freelist_count++; + list_add(&ab->list, &audit_freelist); + } + spin_unlock_irqrestore(&audit_freelist_lock, flags); +} + +static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, + gfp_t gfp_mask, int type) +{ + unsigned long flags; + struct audit_buffer *ab = NULL; + struct nlmsghdr *nlh; + + spin_lock_irqsave(&audit_freelist_lock, flags); + if (!list_empty(&audit_freelist)) { + ab = list_entry(audit_freelist.next, + struct audit_buffer, list); + list_del(&ab->list); + --audit_freelist_count; + } + spin_unlock_irqrestore(&audit_freelist_lock, flags); + + if (!ab) { + ab = kmalloc(sizeof(*ab), gfp_mask); + if (!ab) + goto err; + } + + ab->ctx = ctx; + ab->gfp_mask = gfp_mask; + + ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask); + if (!ab->skb) + goto err; + + nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0); + if (!nlh) + goto out_kfree_skb; + + return ab; + +out_kfree_skb: + kfree_skb(ab->skb); + ab->skb = NULL; +err: + audit_buffer_free(ab); + return NULL; +} + +/** + * audit_serial - compute a serial number for the audit record + * + * Compute a serial number for the audit record. Audit records are + * written to user-space as soon as they are generated, so a complete + * audit record may be written in several pieces. The timestamp of the + * record and this serial number are used by the user-space tools to + * determine which pieces belong to the same audit record. The + * (timestamp,serial) tuple is unique for each syscall and is live from + * syscall entry to syscall exit. + * + * NOTE: Another possibility is to store the formatted records off the + * audit context (for those records that have a context), and emit them + * all at syscall exit. However, this could delay the reporting of + * significant errors until syscall exit (or never, if the system + * halts). + */ +unsigned int audit_serial(void) +{ + static atomic_t serial = ATOMIC_INIT(0); + + return atomic_add_return(1, &serial); +} + +static inline void audit_get_stamp(struct audit_context *ctx, + struct timespec *t, unsigned int *serial) +{ + if (!ctx || !auditsc_get_stamp(ctx, t, serial)) { + *t = CURRENT_TIME; + *serial = audit_serial(); + } +} + +/* + * Wait for auditd to drain the queue a little + */ +static long wait_for_auditd(long sleep_time) +{ + DECLARE_WAITQUEUE(wait, current); + set_current_state(TASK_UNINTERRUPTIBLE); + add_wait_queue_exclusive(&audit_backlog_wait, &wait); + + if (audit_backlog_limit && + skb_queue_len(&audit_skb_queue) > audit_backlog_limit) + sleep_time = schedule_timeout(sleep_time); + + __set_current_state(TASK_RUNNING); + remove_wait_queue(&audit_backlog_wait, &wait); + + return sleep_time; +} + +/** + * audit_log_start - obtain an audit buffer + * @ctx: audit_context (may be NULL) + * @gfp_mask: type of allocation + * @type: audit message type + * + * Returns audit_buffer pointer on success or NULL on error. + * + * Obtain an audit buffer. This routine does locking to obtain the + * audit buffer, but then no locking is required for calls to + * audit_log_*format. If the task (ctx) is a task that is currently in a + * syscall, then the syscall is marked as auditable and an audit record + * will be written at syscall exit. If there is no associated task, then + * task context (ctx) should be NULL. + */ +struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, + int type) +{ + struct audit_buffer *ab = NULL; + struct timespec t; + unsigned int uninitialized_var(serial); + int reserve = 5; /* Allow atomic callers to go up to five + entries over the normal backlog limit */ + unsigned long timeout_start = jiffies; + + if (audit_initialized != AUDIT_INITIALIZED) + return NULL; + + if (unlikely(audit_filter_type(type))) + return NULL; + + if (gfp_mask & __GFP_WAIT) { + if (audit_pid && audit_pid == current->pid) + gfp_mask &= ~__GFP_WAIT; + else + reserve = 0; + } + + while (audit_backlog_limit + && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) { + if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time) { + long sleep_time; + + sleep_time = timeout_start + audit_backlog_wait_time - jiffies; + if (sleep_time > 0) { + sleep_time = wait_for_auditd(sleep_time); + if (sleep_time > 0) + continue; + } + } + if (audit_rate_check() && printk_ratelimit()) + pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n", + skb_queue_len(&audit_skb_queue), + audit_backlog_limit); + audit_log_lost("backlog limit exceeded"); + audit_backlog_wait_time = audit_backlog_wait_overflow; + wake_up(&audit_backlog_wait); + return NULL; + } + + if (!reserve) + audit_backlog_wait_time = audit_backlog_wait_time_master; + + ab = audit_buffer_alloc(ctx, gfp_mask, type); + if (!ab) { + audit_log_lost("out of memory in audit_log_start"); + return NULL; + } + + audit_get_stamp(ab->ctx, &t, &serial); + + audit_log_format(ab, "audit(%lu.%03lu:%u): ", + t.tv_sec, t.tv_nsec/1000000, serial); + return ab; +} + +/** + * audit_expand - expand skb in the audit buffer + * @ab: audit_buffer + * @extra: space to add at tail of the skb + * + * Returns 0 (no space) on failed expansion, or available space if + * successful. + */ +static inline int audit_expand(struct audit_buffer *ab, int extra) +{ + struct sk_buff *skb = ab->skb; + int oldtail = skb_tailroom(skb); + int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask); + int newtail = skb_tailroom(skb); + + if (ret < 0) { + audit_log_lost("out of memory in audit_expand"); + return 0; + } + + skb->truesize += newtail - oldtail; + return newtail; +} + +/* + * Format an audit message into the audit buffer. If there isn't enough + * room in the audit buffer, more room will be allocated and vsnprint + * will be called a second time. Currently, we assume that a printk + * can't format message larger than 1024 bytes, so we don't either. + */ +static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, + va_list args) +{ + int len, avail; + struct sk_buff *skb; + va_list args2; + + if (!ab) + return; + + BUG_ON(!ab->skb); + skb = ab->skb; + avail = skb_tailroom(skb); + if (avail == 0) { + avail = audit_expand(ab, AUDIT_BUFSIZ); + if (!avail) + goto out; + } + va_copy(args2, args); + len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args); + if (len >= avail) { + /* The printk buffer is 1024 bytes long, so if we get + * here and AUDIT_BUFSIZ is at least 1024, then we can + * log everything that printk could have logged. */ + avail = audit_expand(ab, + max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail)); + if (!avail) + goto out_va_end; + len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2); + } + if (len > 0) + skb_put(skb, len); +out_va_end: + va_end(args2); +out: + return; +} + +/** + * audit_log_format - format a message into the audit buffer. + * @ab: audit_buffer + * @fmt: format string + * @...: optional parameters matching @fmt string + * + * All the work is done in audit_log_vformat. + */ +void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) +{ + va_list args; + + if (!ab) + return; + va_start(args, fmt); + audit_log_vformat(ab, fmt, args); + va_end(args); +} + +/** + * audit_log_hex - convert a buffer to hex and append it to the audit skb + * @ab: the audit_buffer + * @buf: buffer to convert to hex + * @len: length of @buf to be converted + * + * No return value; failure to expand is silently ignored. + * + * This function will take the passed buf and convert it into a string of + * ascii hex digits. The new string is placed onto the skb. + */ +void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf, + size_t len) +{ + int i, avail, new_len; + unsigned char *ptr; + struct sk_buff *skb; + + if (!ab) + return; + + BUG_ON(!ab->skb); + skb = ab->skb; + avail = skb_tailroom(skb); + new_len = len<<1; + if (new_len >= avail) { + /* Round the buffer request up to the next multiple */ + new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1); + avail = audit_expand(ab, new_len); + if (!avail) + return; + } + + ptr = skb_tail_pointer(skb); + for (i = 0; i < len; i++) + ptr = hex_byte_pack_upper(ptr, buf[i]); + *ptr = 0; + skb_put(skb, len << 1); /* new string is twice the old string */ +} + +/* + * Format a string of no more than slen characters into the audit buffer, + * enclosed in quote marks. + */ +void audit_log_n_string(struct audit_buffer *ab, const char *string, + size_t slen) +{ + int avail, new_len; + unsigned char *ptr; + struct sk_buff *skb; + + if (!ab) + return; + + BUG_ON(!ab->skb); + skb = ab->skb; + avail = skb_tailroom(skb); + new_len = slen + 3; /* enclosing quotes + null terminator */ + if (new_len > avail) { + avail = audit_expand(ab, new_len); + if (!avail) + return; + } + ptr = skb_tail_pointer(skb); + *ptr++ = '"'; + memcpy(ptr, string, slen); + ptr += slen; + *ptr++ = '"'; + *ptr = 0; + skb_put(skb, slen + 2); /* don't include null terminator */ +} + +/** + * audit_string_contains_control - does a string need to be logged in hex + * @string: string to be checked + * @len: max length of the string to check + */ +int audit_string_contains_control(const char *string, size_t len) +{ + const unsigned char *p; + for (p = string; p < (const unsigned char *)string + len; p++) { + if (*p == '"' || *p < 0x21 || *p > 0x7e) + return 1; + } + return 0; +} + +/** + * audit_log_n_untrustedstring - log a string that may contain random characters + * @ab: audit_buffer + * @len: length of string (not including trailing null) + * @string: string to be logged + * + * This code will escape a string that is passed to it if the string + * contains a control character, unprintable character, double quote mark, + * or a space. Unescaped strings will start and end with a double quote mark. + * Strings that are escaped are printed in hex (2 digits per char). + * + * The caller specifies the number of characters in the string to log, which may + * or may not be the entire string. + */ +void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string, + size_t len) +{ + if (audit_string_contains_control(string, len)) + audit_log_n_hex(ab, string, len); + else + audit_log_n_string(ab, string, len); +} + +/** + * audit_log_untrustedstring - log a string that may contain random characters + * @ab: audit_buffer + * @string: string to be logged + * + * Same as audit_log_n_untrustedstring(), except that strlen is used to + * determine string length. + */ +void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) +{ + audit_log_n_untrustedstring(ab, string, strlen(string)); +} + +/* This is a helper-function to print the escaped d_path */ +void audit_log_d_path(struct audit_buffer *ab, const char *prefix, + const struct path *path) +{ + char *p, *pathname; + + if (prefix) + audit_log_format(ab, "%s", prefix); + + /* We will allow 11 spaces for ' (deleted)' to be appended */ + pathname = kmalloc(PATH_MAX+11, ab->gfp_mask); + if (!pathname) { + audit_log_string(ab, "<no_memory>"); + return; + } + p = d_path(path, pathname, PATH_MAX+11); + if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */ + /* FIXME: can we save some information here? */ + audit_log_string(ab, "<too_long>"); + } else + audit_log_untrustedstring(ab, p); + kfree(pathname); +} + +void audit_log_session_info(struct audit_buffer *ab) +{ + unsigned int sessionid = audit_get_sessionid(current); + uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current)); + + audit_log_format(ab, " auid=%u ses=%u", auid, sessionid); +} + +void audit_log_key(struct audit_buffer *ab, char *key) +{ + audit_log_format(ab, " key="); + if (key) + audit_log_untrustedstring(ab, key); + else + audit_log_format(ab, "(null)"); +} + +void audit_log_cap(struct audit_buffer *ab, char *prefix, kernel_cap_t *cap) +{ + int i; + + audit_log_format(ab, " %s=", prefix); + CAP_FOR_EACH_U32(i) { + audit_log_format(ab, "%08x", + cap->cap[CAP_LAST_U32 - i]); + } +} + +static void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name) +{ + kernel_cap_t *perm = &name->fcap.permitted; + kernel_cap_t *inh = &name->fcap.inheritable; + int log = 0; + + if (!cap_isclear(*perm)) { + audit_log_cap(ab, "cap_fp", perm); + log = 1; + } + if (!cap_isclear(*inh)) { + audit_log_cap(ab, "cap_fi", inh); + log = 1; + } + + if (log) + audit_log_format(ab, " cap_fe=%d cap_fver=%x", + name->fcap.fE, name->fcap_ver); +} + +static inline int audit_copy_fcaps(struct audit_names *name, + const struct dentry *dentry) +{ + struct cpu_vfs_cap_data caps; + int rc; + + if (!dentry) + return 0; + + rc = get_vfs_caps_from_disk(dentry, &caps); + if (rc) + return rc; + + name->fcap.permitted = caps.permitted; + name->fcap.inheritable = caps.inheritable; + name->fcap.fE = !!(caps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE); + name->fcap_ver = (caps.magic_etc & VFS_CAP_REVISION_MASK) >> + VFS_CAP_REVISION_SHIFT; + + return 0; +} + +/* Copy inode data into an audit_names. */ +void audit_copy_inode(struct audit_names *name, const struct dentry *dentry, + const struct inode *inode) +{ + name->ino = inode->i_ino; + name->dev = inode->i_sb->s_dev; + name->mode = inode->i_mode; + name->uid = inode->i_uid; + name->gid = inode->i_gid; + name->rdev = inode->i_rdev; + security_inode_getsecid(inode, &name->osid); + audit_copy_fcaps(name, dentry); +} + +/** + * audit_log_name - produce AUDIT_PATH record from struct audit_names + * @context: audit_context for the task + * @n: audit_names structure with reportable details + * @path: optional path to report instead of audit_names->name + * @record_num: record number to report when handling a list of names + * @call_panic: optional pointer to int that will be updated if secid fails + */ +void audit_log_name(struct audit_context *context, struct audit_names *n, + struct path *path, int record_num, int *call_panic) +{ + struct audit_buffer *ab; + ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH); + if (!ab) + return; + + audit_log_format(ab, "item=%d", record_num); + + if (path) + audit_log_d_path(ab, " name=", path); + else if (n->name) { + switch (n->name_len) { + case AUDIT_NAME_FULL: + /* log the full path */ + audit_log_format(ab, " name="); + audit_log_untrustedstring(ab, n->name->name); + break; + case 0: + /* name was specified as a relative path and the + * directory component is the cwd */ + audit_log_d_path(ab, " name=", &context->pwd); + break; + default: + /* log the name's directory component */ + audit_log_format(ab, " name="); + audit_log_n_untrustedstring(ab, n->name->name, + n->name_len); + } + } else + audit_log_format(ab, " name=(null)"); + + if (n->ino != (unsigned long)-1) + audit_log_format(ab, " inode=%lu" + " dev=%02x:%02x mode=%#ho" + " ouid=%u ogid=%u rdev=%02x:%02x", + n->ino, + MAJOR(n->dev), + MINOR(n->dev), + n->mode, + from_kuid(&init_user_ns, n->uid), + from_kgid(&init_user_ns, n->gid), + MAJOR(n->rdev), + MINOR(n->rdev)); + if (n->osid != 0) { + char *ctx = NULL; + u32 len; + if (security_secid_to_secctx( + n->osid, &ctx, &len)) { + audit_log_format(ab, " osid=%u", n->osid); + if (call_panic) + *call_panic = 2; + } else { + audit_log_format(ab, " obj=%s", ctx); + security_release_secctx(ctx, len); + } + } + + /* log the audit_names record type */ + audit_log_format(ab, " nametype="); + switch(n->type) { + case AUDIT_TYPE_NORMAL: + audit_log_format(ab, "NORMAL"); + break; + case AUDIT_TYPE_PARENT: + audit_log_format(ab, "PARENT"); + break; + case AUDIT_TYPE_CHILD_DELETE: + audit_log_format(ab, "DELETE"); + break; + case AUDIT_TYPE_CHILD_CREATE: + audit_log_format(ab, "CREATE"); + break; + default: + audit_log_format(ab, "UNKNOWN"); + break; + } + + audit_log_fcaps(ab, n); + audit_log_end(ab); +} + +int audit_log_task_context(struct audit_buffer *ab) +{ + char *ctx = NULL; + unsigned len; + int error; + u32 sid; + + security_task_getsecid(current, &sid); + if (!sid) + return 0; + + error = security_secid_to_secctx(sid, &ctx, &len); + if (error) { + if (error != -EINVAL) + goto error_path; + return 0; + } + + audit_log_format(ab, " subj=%s", ctx); + security_release_secctx(ctx, len); + return 0; + +error_path: + audit_panic("error in audit_log_task_context"); + return error; +} +EXPORT_SYMBOL(audit_log_task_context); + +void audit_log_d_path_exe(struct audit_buffer *ab, + struct mm_struct *mm) +{ + struct file *exe_file; + + if (!mm) + goto out_null; + + exe_file = get_mm_exe_file(mm); + if (!exe_file) + goto out_null; + + audit_log_d_path(ab, " exe=", &exe_file->f_path); + fput(exe_file); + return; +out_null: + audit_log_format(ab, " exe=(null)"); +} + +void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk) +{ + const struct cred *cred; + char comm[sizeof(tsk->comm)]; + char *tty; + + if (!ab) + return; + + /* tsk == current */ + cred = current_cred(); + + spin_lock_irq(&tsk->sighand->siglock); + if (tsk->signal && tsk->signal->tty && tsk->signal->tty->name) + tty = tsk->signal->tty->name; + else + tty = "(none)"; + spin_unlock_irq(&tsk->sighand->siglock); + + audit_log_format(ab, + " ppid=%d pid=%d auid=%u uid=%u gid=%u" + " euid=%u suid=%u fsuid=%u" + " egid=%u sgid=%u fsgid=%u tty=%s ses=%u", + task_ppid_nr(tsk), + task_pid_nr(tsk), + from_kuid(&init_user_ns, audit_get_loginuid(tsk)), + from_kuid(&init_user_ns, cred->uid), + from_kgid(&init_user_ns, cred->gid), + from_kuid(&init_user_ns, cred->euid), + from_kuid(&init_user_ns, cred->suid), + from_kuid(&init_user_ns, cred->fsuid), + from_kgid(&init_user_ns, cred->egid), + from_kgid(&init_user_ns, cred->sgid), + from_kgid(&init_user_ns, cred->fsgid), + tty, audit_get_sessionid(tsk)); + + audit_log_format(ab, " comm="); + audit_log_untrustedstring(ab, get_task_comm(comm, tsk)); + + audit_log_d_path_exe(ab, tsk->mm); + audit_log_task_context(ab); +} +EXPORT_SYMBOL(audit_log_task_info); + +/** + * audit_log_link_denied - report a link restriction denial + * @operation: specific link opreation + * @link: the path that triggered the restriction + */ +void audit_log_link_denied(const char *operation, struct path *link) +{ + struct audit_buffer *ab; + struct audit_names *name; + + name = kzalloc(sizeof(*name), GFP_NOFS); + if (!name) + return; + + /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */ + ab = audit_log_start(current->audit_context, GFP_KERNEL, + AUDIT_ANOM_LINK); + if (!ab) + goto out; + audit_log_format(ab, "op=%s", operation); + audit_log_task_info(ab, current); + audit_log_format(ab, " res=0"); + audit_log_end(ab); + + /* Generate AUDIT_PATH record with object. */ + name->type = AUDIT_TYPE_NORMAL; + audit_copy_inode(name, link->dentry, d_backing_inode(link->dentry)); + audit_log_name(current->audit_context, name, link, 0, NULL); +out: + kfree(name); +} + +/** + * audit_log_end - end one audit record + * @ab: the audit_buffer + * + * netlink_unicast() cannot be called inside an irq context because it blocks + * (last arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed + * on a queue and a tasklet is scheduled to remove them from the queue outside + * the irq context. May be called in any context. + */ +void audit_log_end(struct audit_buffer *ab) +{ + if (!ab) + return; + if (!audit_rate_check()) { + audit_log_lost("rate limit exceeded"); + } else { + struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); + + nlh->nlmsg_len = ab->skb->len; + kauditd_send_multicast_skb(ab->skb, ab->gfp_mask); + + /* + * The original kaudit unicast socket sends up messages with + * nlmsg_len set to the payload length rather than the entire + * message length. This breaks the standard set by netlink. + * The existing auditd daemon assumes this breakage. Fixing + * this would require co-ordinating a change in the established + * protocol between the kaudit kernel subsystem and the auditd + * userspace code. + */ + nlh->nlmsg_len -= NLMSG_HDRLEN; + + if (audit_pid) { + skb_queue_tail(&audit_skb_queue, ab->skb); + wake_up_interruptible(&kauditd_wait); + } else { + audit_printk_skb(ab->skb); + } + ab->skb = NULL; + } + audit_buffer_free(ab); +} + +/** + * audit_log - Log an audit record + * @ctx: audit context + * @gfp_mask: type of allocation + * @type: audit message type + * @fmt: format string to use + * @...: variable parameters matching the format string + * + * This is a convenience function that calls audit_log_start, + * audit_log_vformat, and audit_log_end. It may be called + * in any context. + */ +void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type, + const char *fmt, ...) +{ + struct audit_buffer *ab; + va_list args; + + ab = audit_log_start(ctx, gfp_mask, type); + if (ab) { + va_start(args, fmt); + audit_log_vformat(ab, fmt, args); + va_end(args); + audit_log_end(ab); + } +} + +#ifdef CONFIG_SECURITY +/** + * audit_log_secctx - Converts and logs SELinux context + * @ab: audit_buffer + * @secid: security number + * + * This is a helper function that calls security_secid_to_secctx to convert + * secid to secctx and then adds the (converted) SELinux context to the audit + * log by calling audit_log_format, thus also preventing leak of internal secid + * to userspace. If secid cannot be converted audit_panic is called. + */ +void audit_log_secctx(struct audit_buffer *ab, u32 secid) +{ + u32 len; + char *secctx; + + if (security_secid_to_secctx(secid, &secctx, &len)) { + audit_panic("Cannot convert secid to context"); + } else { + audit_log_format(ab, " obj=%s", secctx); + security_release_secctx(secctx, len); + } +} +EXPORT_SYMBOL(audit_log_secctx); +#endif + +EXPORT_SYMBOL(audit_log_start); +EXPORT_SYMBOL(audit_log_end); +EXPORT_SYMBOL(audit_log_format); +EXPORT_SYMBOL(audit_log); |