diff options
Diffstat (limited to 'kernel/audit.c')
| -rw-r--r-- | kernel/audit.c | 1520 |
1 files changed, 1520 insertions, 0 deletions
diff --git a/kernel/audit.c b/kernel/audit.c new file mode 100644 index 0000000..ce6d8ea --- /dev/null +++ b/kernel/audit.c @@ -0,0 +1,1520 @@ +/* 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 <asm/atomic.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/err.h> +#include <linux/kthread.h> + +#include <linux/audit.h> + +#include <net/sock.h> +#include <net/netlink.h> +#include <linux/skbuff.h> +#include <linux/netlink.h> +#include <linux/inotify.h> +#include <linux/freezer.h> +#include <linux/tty.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; + +/* 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_pid contains + * the pid to use to send netlink messages to that process. + */ +int audit_pid; +static int audit_nlk_pid; + +/* 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. */ +uid_t audit_sig_uid = -1; +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; + +/* Inotify handle. */ +struct inotify_handle *audit_ih; + +/* 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. */ +static 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, + uid_t loginuid, u32 sessionid, u32 sid, + int allow_changes) +{ + struct audit_buffer *ab; + int rc = 0; + + ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE); + audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new, + old, loginuid, sessionid); + if (sid) { + char *ctx = NULL; + u32 len; + + rc = security_secid_to_secctx(sid, &ctx, &len); + if (rc) { + audit_log_format(ab, " sid=%u", sid); + allow_changes = 0; /* Something weird, deny request */ + } else { + audit_log_format(ab, " subj=%s", ctx); + security_release_secctx(ctx, len); + } + } + 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, uid_t loginuid, u32 sessionid, + u32 sid) +{ + 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, loginuid, + sessionid, sid, 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, uid_t loginuid, u32 sessionid, + u32 sid) +{ + return audit_do_config_change("audit_rate_limit", &audit_rate_limit, + limit, loginuid, sessionid, sid); +} + +static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid, + u32 sid) +{ + return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, + limit, loginuid, sessionid, sid); +} + +static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid) +{ + int rc; + if (state < AUDIT_OFF || state > AUDIT_LOCKED) + return -EINVAL; + + rc = audit_do_config_change("audit_enabled", &audit_enabled, state, + loginuid, sessionid, sid); + + if (!rc) + audit_ever_enabled |= !!state; + + return rc; +} + +static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid) +{ + 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, + loginuid, sessionid, sid); +} + +/* + * 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); +} + +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_pid, 0); + if (err < 0) { + BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */ + printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid); + audit_log_lost("auditd dissapeared\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 */ + kfree_skb(skb); +} + +static int kauditd_thread(void *dummy) +{ + struct sk_buff *skb; + + set_freezable(); + while (!kthread_should_stop()) { + /* + * 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. + */ + if (audit_default && audit_pid) { + skb = skb_dequeue(&audit_skb_hold_queue); + if (unlikely(skb)) { + while (skb && audit_pid) { + kauditd_send_skb(skb); + skb = skb_dequeue(&audit_skb_hold_queue); + } + } + } + + skb = skb_dequeue(&audit_skb_queue); + wake_up(&audit_backlog_wait); + if (skb) { + if (audit_pid) + kauditd_send_skb(skb); + else { + if (printk_ratelimit()) + printk(KERN_NOTICE "%s\n", skb->data + NLMSG_SPACE(0)); + else + audit_log_lost("printk limit exceeded\n"); + + audit_hold_skb(skb); + } + } else { + DECLARE_WAITQUEUE(wait, current); + 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; +} + +static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid) +{ + struct task_struct *tsk; + int err; + + read_lock(&tasklist_lock); + tsk = find_task_by_vpid(pid); + err = -ESRCH; + if (!tsk) + goto out; + err = 0; + + spin_lock_irq(&tsk->sighand->siglock); + if (!tsk->signal->audit_tty) + err = -EPERM; + spin_unlock_irq(&tsk->sighand->siglock); + if (err) + goto out; + + tty_audit_push_task(tsk, loginuid, sessionid); +out: + read_unlock(&tasklist_lock); + return err; +} + +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; +} + +#ifdef CONFIG_AUDIT_TREE +static int prune_tree_thread(void *unused) +{ + mutex_lock(&audit_cmd_mutex); + audit_prune_trees(); + mutex_unlock(&audit_cmd_mutex); + return 0; +} + +void audit_schedule_prune(void) +{ + kthread_run(prune_tree_thread, NULL, "audit_prune_tree"); +} +#endif + +struct sk_buff *audit_make_reply(int pid, int seq, int type, int done, + int multi, void *payload, int size) +{ + struct sk_buff *skb; + struct nlmsghdr *nlh; + int len = NLMSG_SPACE(size); + void *data; + int flags = multi ? NLM_F_MULTI : 0; + int t = done ? NLMSG_DONE : type; + + skb = alloc_skb(len, GFP_KERNEL); + if (!skb) + return NULL; + + nlh = NLMSG_PUT(skb, pid, seq, t, size); + nlh->nlmsg_flags = flags; + data = NLMSG_DATA(nlh); + memcpy(data, payload, size); + return skb; + +nlmsg_failure: /* Used by NLMSG_PUT */ + if (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. + */ +void audit_send_reply(int pid, int seq, int type, int done, int multi, + 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; + + switch (msg_type) { + case AUDIT_GET: + case AUDIT_LIST: + case AUDIT_LIST_RULES: + case AUDIT_SET: + case AUDIT_ADD: + case AUDIT_ADD_RULE: + case AUDIT_DEL: + case AUDIT_DEL_RULE: + case AUDIT_SIGNAL_INFO: + case AUDIT_TTY_GET: + case AUDIT_TTY_SET: + case AUDIT_TRIM: + case AUDIT_MAKE_EQUIV: + if (security_netlink_recv(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 (security_netlink_recv(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, + u32 pid, u32 uid, uid_t auid, u32 ses, + u32 sid) +{ + int rc = 0; + char *ctx = NULL; + u32 len; + + if (!audit_enabled) { + *ab = NULL; + return rc; + } + + *ab = audit_log_start(NULL, GFP_KERNEL, msg_type); + audit_log_format(*ab, "user pid=%d uid=%u auid=%u ses=%u", + pid, uid, auid, ses); + if (sid) { + rc = security_secid_to_secctx(sid, &ctx, &len); + if (rc) + audit_log_format(*ab, " ssid=%u", sid); + else { + audit_log_format(*ab, " subj=%s", ctx); + security_release_secctx(ctx, len); + } + } + + return rc; +} + +static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) +{ + u32 uid, pid, seq, sid; + void *data; + struct audit_status *status_get, status_set; + int err; + struct audit_buffer *ab; + u16 msg_type = nlh->nlmsg_type; + uid_t loginuid; /* loginuid of sender */ + u32 sessionid; + 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; + } + + pid = NETLINK_CREDS(skb)->pid; + uid = NETLINK_CREDS(skb)->uid; + loginuid = NETLINK_CB(skb).loginuid; + sessionid = NETLINK_CB(skb).sessionid; + sid = NETLINK_CB(skb).sid; + 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).pid, 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, + loginuid, sessionid, sid); + if (err < 0) + return err; + } + if (status_get->mask & AUDIT_STATUS_FAILURE) { + err = audit_set_failure(status_get->failure, + loginuid, sessionid, sid); + 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, loginuid, + sessionid, sid, 1); + + audit_pid = new_pid; + audit_nlk_pid = NETLINK_CB(skb).pid; + } + if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) { + err = audit_set_rate_limit(status_get->rate_limit, + loginuid, sessionid, sid); + if (err < 0) + return err; + } + if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) + err = audit_set_backlog_limit(status_get->backlog_limit, + loginuid, sessionid, sid); + 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(&NETLINK_CB(skb)); + if (err == 1) { + err = 0; + if (msg_type == AUDIT_USER_TTY) { + err = audit_prepare_user_tty(pid, loginuid, + sessionid); + if (err) + break; + } + audit_log_common_recv_msg(&ab, msg_type, pid, uid, + loginuid, sessionid, sid); + + if (msg_type != AUDIT_USER_TTY) + audit_log_format(ab, " msg='%.1024s'", + (char *)data); + else { + int size; + + audit_log_format(ab, " msg="); + size = nlmsg_len(nlh); + audit_log_n_untrustedstring(ab, data, size); + } + audit_set_pid(ab, pid); + audit_log_end(ab); + } + break; + case AUDIT_ADD: + case AUDIT_DEL: + if (nlmsg_len(nlh) < sizeof(struct audit_rule)) + return -EINVAL; + if (audit_enabled == AUDIT_LOCKED) { + audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, + uid, loginuid, sessionid, sid); + + audit_log_format(ab, " audit_enabled=%d res=0", + audit_enabled); + audit_log_end(ab); + return -EPERM; + } + /* fallthrough */ + case AUDIT_LIST: + err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid, + uid, seq, data, nlmsg_len(nlh), + loginuid, sessionid, sid); + 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, pid, + uid, loginuid, sessionid, sid); + + 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).pid, + uid, seq, data, nlmsg_len(nlh), + loginuid, sessionid, sid); + break; + case AUDIT_TRIM: + audit_trim_trees(); + + audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, + uid, loginuid, sessionid, sid); + + 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, pid, + uid, loginuid, sessionid, sid); + + 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: + 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) { + security_release_secctx(ctx, len); + return -ENOMEM; + } + sig_data->uid = audit_sig_uid; + sig_data->pid = audit_sig_pid; + memcpy(sig_data->ctx, ctx, len); + security_release_secctx(ctx, len); + audit_send_reply(NETLINK_CB(skb).pid, 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; + + read_lock(&tasklist_lock); + tsk = find_task_by_vpid(pid); + if (!tsk) + err = -ESRCH; + else { + spin_lock_irq(&tsk->sighand->siglock); + s.enabled = tsk->signal->audit_tty != 0; + spin_unlock_irq(&tsk->sighand->siglock); + } + read_unlock(&tasklist_lock); + audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_TTY_GET, 0, 0, + &s, sizeof(s)); + break; + } + case AUDIT_TTY_SET: { + struct audit_tty_status *s; + struct task_struct *tsk; + + if (nlh->nlmsg_len < sizeof(struct audit_tty_status)) + return -EINVAL; + s = data; + if (s->enabled != 0 && s->enabled != 1) + return -EINVAL; + read_lock(&tasklist_lock); + tsk = find_task_by_vpid(pid); + if (!tsk) + err = -ESRCH; + else { + spin_lock_irq(&tsk->sighand->siglock); + tsk->signal->audit_tty = s->enabled != 0; + spin_unlock_irq(&tsk->sighand->siglock); + } + read_unlock(&tasklist_lock); + break; + } + default: + err = -EINVAL; + break; + } + + return err < 0 ? err : 0; +} + +/* + * Get message from skb (based on rtnetlink_rcv_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) +{ + int err; + struct nlmsghdr *nlh; + u32 rlen; + + while (skb->len >= NLMSG_SPACE(0)) { + nlh = nlmsg_hdr(skb); + if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) + return; + rlen = NLMSG_ALIGN(nlh->nlmsg_len); + if (rlen > skb->len) + rlen = skb->len; + if ((err = audit_receive_msg(skb, nlh))) { + netlink_ack(skb, nlh, err); + } else if (nlh->nlmsg_flags & NLM_F_ACK) + netlink_ack(skb, nlh, 0); + skb_pull(skb, rlen); + } +} + +/* 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); +} + +#ifdef CONFIG_AUDITSYSCALL +static const struct inotify_operations audit_inotify_ops = { + .handle_event = audit_handle_ievent, + .destroy_watch = audit_free_parent, +}; +#endif + +/* Initialize audit support at boot time. */ +static int __init audit_init(void) +{ + int i; + + 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, 0, + audit_receive, NULL, THIS_MODULE); + 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"); + +#ifdef CONFIG_AUDITSYSCALL + audit_ih = inotify_init(&audit_inotify_ops); + if (IS_ERR(audit_ih)) + audit_panic("cannot initialize inotify handle"); +#endif + + 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->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask); + if (!ab->skb) + goto err; + + ab->ctx = ctx; + ab->gfp_mask = gfp_mask; + nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0)); + nlh->nlmsg_type = type; + nlh->nlmsg_flags = 0; + nlh->nlmsg_pid = 0; + nlh->nlmsg_seq = 0; + return ab; +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(); + } +} + +/* 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 + && time_before(jiffies, timeout_start + audit_backlog_wait_time)) { + + /* Wait for auditd to drain the queue a little */ + 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(timeout_start + audit_backlog_wait_time - jiffies); + + __set_current_state(TASK_RUNNING); + remove_wait_queue(&audit_backlog_wait, &wait); + 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; + len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2); + } + va_end(args2); + if (len > 0) + skb_put(skb, len); +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; 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, + 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_format(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_format(ab, "<too long>"); + } else + audit_log_untrustedstring(ab, p); + kfree(pathname); +} + +/** + * 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_SPACE(0); + + if (audit_pid) { + skb_queue_tail(&audit_skb_queue, ab->skb); + wake_up_interruptible(&kauditd_wait); + } else { + if (nlh->nlmsg_type != AUDIT_EOE) { + if (printk_ratelimit()) { + printk(KERN_NOTICE "type=%d %s\n", + nlh->nlmsg_type, + ab->skb->data + NLMSG_SPACE(0)); + } else + audit_log_lost("printk limit exceeded\n"); + } + audit_hold_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); + } +} + +EXPORT_SYMBOL(audit_log_start); +EXPORT_SYMBOL(audit_log_end); +EXPORT_SYMBOL(audit_log_format); +EXPORT_SYMBOL(audit_log); |
