/* 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/ */ #include <linux/init.h> #include <asm/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 <net/netlink.h> #include <linux/freezer.h> #include <linux/tty.h> #include <linux/pid_namespace.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 int audit_enabled; int audit_ever_enabled; EXPORT_SYMBOL_GPL(audit_enabled); /* Default state when kernel boots without any parameters. */ static int audit_default; /* If auditing cannot proceed, audit_failure selects what happens. */ static int 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 int 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 int audit_rate_limit; /* Number of outstanding audit_buffers allowed. */ static int audit_backlog_limit = 64; static int audit_backlog_wait_time = 60 * HZ; static int 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; /* 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); /* 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 { int pid; struct sk_buff *skb; }; static void audit_set_pid(struct audit_buffer *ab, pid_t pid) { if (ab) { struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); nlh->nlmsg_pid = pid; } } void audit_panic(const char *message) { switch (audit_failure) { case AUDIT_FAIL_SILENT: break; case AUDIT_FAIL_PRINTK: if (printk_ratelimit()) printk(KERN_ERR "audit: %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()) printk(KERN_WARNING "audit: audit_lost=%d audit_rate_limit=%d " "audit_backlog_limit=%d\n", atomic_read(&audit_lost), audit_rate_limit, audit_backlog_limit); audit_panic(message); } } static int audit_log_config_change(char *function_name, int new, int 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=%d old=%d", 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, int *to_change, int new) { int allow_changes, rc = 0, 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(int limit) { return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit); } static int audit_set_backlog_limit(int limit) { return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit); } static int audit_set_enabled(int state) { int rc; if (state < AUDIT_OFF || 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(int 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 && 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()) printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data); else audit_log_lost("printk limit exceeded\n"); } 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 */ printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid); audit_log_lost("auditd disappeared\n"); audit_pid = 0; /* 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); } /* * 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; DECLARE_WAITQUEUE(wait, current); flush_hold_queue(); skb = skb_dequeue(&audit_skb_queue); wake_up(&audit_backlog_wait); if (skb) { if (audit_pid) kauditd_send_skb(skb); else audit_printk_skb(skb); continue; } set_current_state(TASK_INTERRUPTIBLE); add_wait_queue(&kauditd_wait, &wait); if (!skb_queue_len(&audit_skb_queue)) { try_to_freeze(); schedule(); } __set_current_state(TASK_RUNNING); remove_wait_queue(&kauditd_wait, &wait); } return 0; } int audit_send_list(void *_dest) { struct audit_netlink_list *dest = _dest; int pid = dest->pid; struct sk_buff *skb; /* 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(audit_sock, skb, pid, 0); kfree(dest); return 0; } struct sk_buff *audit_make_reply(int pid, 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, pid, 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; 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(audit_sock, reply->skb, reply->pid, 0); kfree(reply); return 0; } /** * audit_send_reply - send an audit reply message via netlink * @pid: process id to send reply to * @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 pid. * No failure notifications. */ static void audit_send_reply(int pid, int seq, int type, int done, int multi, const void *payload, int size) { 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(pid, seq, type, done, multi, payload, size); if (!skb) goto out; reply->pid = pid; 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 the initial namespaces for now. */ if ((current_user_ns() != &init_user_ns) || (task_active_pid_ns(current) != &init_pid_ns)) return -EPERM; switch (msg_type) { case AUDIT_LIST: case AUDIT_ADD: case AUDIT_DEL: return -EOPNOTSUPP; case AUDIT_GET: case AUDIT_SET: 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: if (!capable(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 (!capable(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()); if (!audit_enabled) { *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", task_tgid_vnr(current), uid); audit_log_session_info(*ab); audit_log_task_context(*ab); return rc; } static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) { u32 seq; void *data; struct audit_status *status_get, status_set; 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: status_set.enabled = audit_enabled; status_set.failure = audit_failure; status_set.pid = audit_pid; status_set.rate_limit = audit_rate_limit; status_set.backlog_limit = audit_backlog_limit; status_set.lost = atomic_read(&audit_lost); status_set.backlog = skb_queue_len(&audit_skb_queue); audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_GET, 0, 0, &status_set, sizeof(status_set)); break; case AUDIT_SET: if (nlh->nlmsg_len < sizeof(struct audit_status)) return -EINVAL; status_get = (struct audit_status *)data; if (status_get->mask & AUDIT_STATUS_ENABLED) { err = audit_set_enabled(status_get->enabled); if (err < 0) return err; } if (status_get->mask & AUDIT_STATUS_FAILURE) { err = audit_set_failure(status_get->failure); if (err < 0) return err; } if (status_get->mask & AUDIT_STATUS_PID) { int new_pid = status_get->pid; 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; } if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) { err = audit_set_rate_limit(status_get->rate_limit); if (err < 0) return err; } if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) err = audit_set_backlog_limit(status_get->backlog_limit); 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) { err = 0; if (msg_type == AUDIT_USER_TTY) { err = tty_audit_push_current(); if (err) break; } audit_log_common_recv_msg(&ab, msg_type); if (msg_type != AUDIT_USER_TTY) audit_log_format(ab, " msg='%.1024s'", (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_pid(ab, NETLINK_CB(skb).portid); audit_log_end(ab); } 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; } /* fallthrough */ case AUDIT_LIST_RULES: err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid, seq, data, nlmsg_len(nlh)); 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(NETLINK_CB(skb).portid, 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 != 0; s.log_passwd = tsk->signal->audit_tty_log_passwd; spin_unlock(&tsk->sighand->siglock); audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s)); break; } case AUDIT_TTY_SET: { struct audit_tty_status s; struct task_struct *tsk = current; memset(&s, 0, sizeof(s)); /* guard against past and future API changes */ memcpy(&s, data, min(sizeof(s), (size_t)nlh->nlmsg_len)); if ((s.enabled != 0 && s.enabled != 1) || (s.log_passwd != 0 && s.log_passwd != 1)) return -EINVAL; spin_lock(&tsk->sighand->siglock); tsk->signal->audit_tty = s.enabled; tsk->signal->audit_tty_log_passwd = s.log_passwd; spin_unlock(&tsk->sighand->siglock); 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); } /* Initialize audit support at boot time. */ static int __init audit_init(void) { int i; struct netlink_kernel_cfg cfg = { .input = audit_receive, }; if (audit_initialized == AUDIT_DISABLED) return 0; printk(KERN_INFO "audit: initializing netlink socket (%s)\n", audit_default ? "enabled" : "disabled"); audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, &cfg); if (!audit_sock) audit_panic("cannot initialize netlink socket"); else audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT; 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; printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled"); if (audit_initialized == AUDIT_INITIALIZED) { audit_enabled = audit_default; audit_ever_enabled |= !!audit_default; } else if (audit_initialized == AUDIT_UNINITIALIZED) { printk(" (after initialization)"); } else { printk(" (until reboot)"); } printk("\n"); return 1; } __setup("audit=", audit_enable); 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 DEFINE_SPINLOCK(serial_lock); static unsigned int serial = 0; unsigned long flags; unsigned int ret; spin_lock_irqsave(&serial_lock, flags); do { ret = ++serial; } while (unlikely(!ret)); spin_unlock_irqrestore(&serial_lock, flags); return ret; } 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 void wait_for_auditd(unsigned long sleep_time) { DECLARE_WAITQUEUE(wait, current); set_current_state(TASK_INTERRUPTIBLE); add_wait_queue(&audit_backlog_wait, &wait); if (audit_backlog_limit && skb_queue_len(&audit_skb_queue) > audit_backlog_limit) schedule_timeout(sleep_time); __set_current_state(TASK_RUNNING); remove_wait_queue(&audit_backlog_wait, &wait); } /* 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 tsk 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, tsk * should be NULL. */ /** * 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; 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) reserve = 0; else reserve = 5; /* Allow atomic callers to go up to five entries over the normal backlog limit */ while (audit_backlog_limit && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) { if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time) { unsigned long sleep_time; sleep_time = timeout_start + audit_backlog_wait_time - jiffies; if ((long)sleep_time > 0) wait_for_auditd(sleep_time); continue; } if (audit_rate_check() && printk_ratelimit()) printk(KERN_WARNING "audit: 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; } 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; static const unsigned char *hex = "0123456789ABCDEF"; 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[(buf[i] & 0xF0)>>4]; /* Upper nibble */ *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */ } *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) { u32 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\n", 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[(_KERNEL_CAPABILITY_U32S-1) - i]); } } 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); } } 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_task_info(struct audit_buffer *ab, struct task_struct *tsk) { const struct cred *cred; char name[sizeof(tsk->comm)]; struct mm_struct *mm = tsk->mm; 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=%ld pid=%d auid=%u uid=%u gid=%u" " euid=%u suid=%u fsuid=%u" " egid=%u sgid=%u fsgid=%u ses=%u tty=%s", sys_getppid(), tsk->pid, 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), audit_get_sessionid(tsk), tty); get_task_comm(name, tsk); audit_log_format(ab, " comm="); audit_log_untrustedstring(ab, name); if (mm) { down_read(&mm->mmap_sem); if (mm->exe_file) audit_log_d_path(ab, " exe=", &mm->exe_file->f_path); up_read(&mm->mmap_sem); } 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, link->dentry->d_inode); audit_log_name(current->audit_context, name, link, 0, NULL); out: kfree(name); } /** * audit_log_end - end one audit record * @ab: the audit_buffer * * The netlink_* functions cannot be called inside an irq context, 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 - 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);