Merge branch 'stable-4.12' of git://git.infradead.org/users/pcmoore/audit

Pull audit updates from Paul Moore:
 "Fourteen audit patches for v4.12 that span the full range of fixes,
  new features, and internal cleanups.

  We have a patches to move to 64-bit timestamps, convert refcounts from
  atomic_t to refcount_t, track PIDs using the pid struct instead of
  pid_t, convert our own private audit buffer cache to a standard
  kmem_cache, log kernel module names when they are unloaded, and
  normalize the NETFILTER_PKT to make the userspace folks happier.

  From a fixes perspective, the most important is likely the auditd
  connection tracking RCU fix; it was a rather brain dead bug that I'll
  take the blame for, but thankfully it didn't seem to affect many
  people (only one report).

  I think the patch subject lines and commit descriptions do a pretty
  good job of explaining the details and why the changes are important
  so I'll point you there instead of duplicating it here; as usual, if
  you have any questions you know where to find us.

  We also manage to take out more code than we put in this time, that
  always makes me happy :)"

* 'stable-4.12' of git://git.infradead.org/users/pcmoore/audit:
  audit: fix the RCU locking for the auditd_connection structure
  audit: use kmem_cache to manage the audit_buffer cache
  audit: Use timespec64 to represent audit timestamps
  audit: store the auditd PID as a pid struct instead of pid_t
  audit: kernel generated netlink traffic should have a portid of 0
  audit: combine audit_receive() and audit_receive_skb()
  audit: convert audit_watch.count from atomic_t to refcount_t
  audit: convert audit_tree.count from atomic_t to refcount_t
  audit: normalize NETFILTER_PKT
  netfilter: use consistent ipv4 network offset in xt_AUDIT
  audit: log module name on delete_module
  audit: remove unnecessary semicolon in audit_watch_handle_event()
  audit: remove unnecessary semicolon in audit_mark_handle_event()
  audit: remove unnecessary semicolon in audit_field_valid()
This commit is contained in:
Linus Torvalds 2017-05-03 09:21:59 -07:00
commit 46f0537b1e
10 changed files with 233 additions and 276 deletions

View file

@ -58,6 +58,8 @@
#include <linux/rcupdate.h>
#include <linux/mutex.h>
#include <linux/gfp.h>
#include <linux/pid.h>
#include <linux/slab.h>
#include <linux/audit.h>
@ -110,18 +112,19 @@ struct audit_net {
* @pid: auditd PID
* @portid: netlink portid
* @net: the associated network namespace
* @lock: spinlock to protect write access
* @rcu: RCU head
*
* Description:
* This struct is RCU protected; you must either hold the RCU lock for reading
* or the included spinlock for writing.
* or the associated spinlock for writing.
*/
static struct auditd_connection {
int pid;
struct pid *pid;
u32 portid;
struct net *net;
spinlock_t lock;
} auditd_conn;
struct rcu_head rcu;
} *auditd_conn = NULL;
static DEFINE_SPINLOCK(auditd_conn_lock);
/* 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
@ -151,12 +154,7 @@ static atomic_t audit_lost = ATOMIC_INIT(0);
/* 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 kmem_cache *audit_buffer_cache;
/* queue msgs to send via kauditd_task */
static struct sk_buff_head audit_queue;
@ -191,17 +189,12 @@ DEFINE_MUTEX(audit_cmd_mutex);
* 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;
@ -220,17 +213,41 @@ struct audit_reply {
* Description:
* Return 1 if the task is a registered audit daemon, 0 otherwise.
*/
int auditd_test_task(const struct task_struct *task)
int auditd_test_task(struct task_struct *task)
{
int rc;
struct auditd_connection *ac;
rcu_read_lock();
rc = (auditd_conn.pid && task->tgid == auditd_conn.pid ? 1 : 0);
ac = rcu_dereference(auditd_conn);
rc = (ac && ac->pid == task_tgid(task) ? 1 : 0);
rcu_read_unlock();
return rc;
}
/**
* auditd_pid_vnr - Return the auditd PID relative to the namespace
*
* Description:
* Returns the PID in relation to the namespace, 0 on failure.
*/
static pid_t auditd_pid_vnr(void)
{
pid_t pid;
const struct auditd_connection *ac;
rcu_read_lock();
ac = rcu_dereference(auditd_conn);
if (!ac || !ac->pid)
pid = 0;
else
pid = pid_vnr(ac->pid);
rcu_read_unlock();
return pid;
}
/**
* audit_get_sk - Return the audit socket for the given network namespace
* @net: the destination network namespace
@ -250,14 +267,6 @@ static struct sock *audit_get_sk(const struct net *net)
return aunet->sk;
}
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) {
@ -426,6 +435,24 @@ static int audit_set_failure(u32 state)
return audit_do_config_change("audit_failure", &audit_failure, state);
}
/**
* auditd_conn_free - RCU helper to release an auditd connection struct
* @rcu: RCU head
*
* Description:
* Drop any references inside the auditd connection tracking struct and free
* the memory.
*/
static void auditd_conn_free(struct rcu_head *rcu)
{
struct auditd_connection *ac;
ac = container_of(rcu, struct auditd_connection, rcu);
put_pid(ac->pid);
put_net(ac->net);
kfree(ac);
}
/**
* auditd_set - Set/Reset the auditd connection state
* @pid: auditd PID
@ -434,22 +461,33 @@ static int audit_set_failure(u32 state)
*
* Description:
* This function will obtain and drop network namespace references as
* necessary.
* necessary. Returns zero on success, negative values on failure.
*/
static void auditd_set(int pid, u32 portid, struct net *net)
static int auditd_set(struct pid *pid, u32 portid, struct net *net)
{
unsigned long flags;
struct auditd_connection *ac_old, *ac_new;
spin_lock_irqsave(&auditd_conn.lock, flags);
auditd_conn.pid = pid;
auditd_conn.portid = portid;
if (auditd_conn.net)
put_net(auditd_conn.net);
if (net)
auditd_conn.net = get_net(net);
else
auditd_conn.net = NULL;
spin_unlock_irqrestore(&auditd_conn.lock, flags);
if (!pid || !net)
return -EINVAL;
ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL);
if (!ac_new)
return -ENOMEM;
ac_new->pid = get_pid(pid);
ac_new->portid = portid;
ac_new->net = get_net(net);
spin_lock_irqsave(&auditd_conn_lock, flags);
ac_old = rcu_dereference_protected(auditd_conn,
lockdep_is_held(&auditd_conn_lock));
rcu_assign_pointer(auditd_conn, ac_new);
spin_unlock_irqrestore(&auditd_conn_lock, flags);
if (ac_old)
call_rcu(&ac_old->rcu, auditd_conn_free);
return 0;
}
/**
@ -544,13 +582,19 @@ static void kauditd_retry_skb(struct sk_buff *skb)
*/
static void auditd_reset(void)
{
unsigned long flags;
struct sk_buff *skb;
struct auditd_connection *ac_old;
/* if it isn't already broken, break the connection */
rcu_read_lock();
if (auditd_conn.pid)
auditd_set(0, 0, NULL);
rcu_read_unlock();
spin_lock_irqsave(&auditd_conn_lock, flags);
ac_old = rcu_dereference_protected(auditd_conn,
lockdep_is_held(&auditd_conn_lock));
rcu_assign_pointer(auditd_conn, NULL);
spin_unlock_irqrestore(&auditd_conn_lock, flags);
if (ac_old)
call_rcu(&ac_old->rcu, auditd_conn_free);
/* flush all of the main and retry queues to the hold queue */
while ((skb = skb_dequeue(&audit_retry_queue)))
@ -576,6 +620,7 @@ static int auditd_send_unicast_skb(struct sk_buff *skb)
u32 portid;
struct net *net;
struct sock *sk;
struct auditd_connection *ac;
/* NOTE: we can't call netlink_unicast while in the RCU section so
* take a reference to the network namespace and grab local
@ -585,15 +630,15 @@ static int auditd_send_unicast_skb(struct sk_buff *skb)
* section netlink_unicast() should safely return an error */
rcu_read_lock();
if (!auditd_conn.pid) {
ac = rcu_dereference(auditd_conn);
if (!ac) {
rcu_read_unlock();
rc = -ECONNREFUSED;
goto err;
}
net = auditd_conn.net;
get_net(net);
net = get_net(ac->net);
sk = audit_get_sk(net);
portid = auditd_conn.portid;
portid = ac->portid;
rcu_read_unlock();
rc = netlink_unicast(sk, skb, portid, 0);
@ -728,6 +773,7 @@ static int kauditd_thread(void *dummy)
u32 portid = 0;
struct net *net = NULL;
struct sock *sk = NULL;
struct auditd_connection *ac;
#define UNICAST_RETRIES 5
@ -735,14 +781,14 @@ static int kauditd_thread(void *dummy)
while (!kthread_should_stop()) {
/* NOTE: see the lock comments in auditd_send_unicast_skb() */
rcu_read_lock();
if (!auditd_conn.pid) {
ac = rcu_dereference(auditd_conn);
if (!ac) {
rcu_read_unlock();
goto main_queue;
}
net = auditd_conn.net;
get_net(net);
net = get_net(ac->net);
sk = audit_get_sk(net);
portid = auditd_conn.portid;
portid = ac->portid;
rcu_read_unlock();
/* attempt to flush the hold queue */
@ -816,7 +862,7 @@ int audit_send_list(void *_dest)
return 0;
}
struct sk_buff *audit_make_reply(__u32 portid, int seq, int type, int done,
struct sk_buff *audit_make_reply(int seq, int type, int done,
int multi, const void *payload, int size)
{
struct sk_buff *skb;
@ -829,7 +875,7 @@ struct sk_buff *audit_make_reply(__u32 portid, int seq, int type, int done,
if (!skb)
return NULL;
nlh = nlmsg_put(skb, portid, seq, t, size, flags);
nlh = nlmsg_put(skb, 0, seq, t, size, flags);
if (!nlh)
goto out_kfree_skb;
data = nlmsg_data(nlh);
@ -873,7 +919,6 @@ static int audit_send_reply_thread(void *arg)
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;
@ -883,12 +928,12 @@ static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int
if (!reply)
return;
skb = audit_make_reply(portid, seq, type, done, multi, payload, size);
skb = audit_make_reply(seq, type, done, multi, payload, size);
if (!skb)
goto out;
reply->net = get_net(net);
reply->portid = portid;
reply->portid = NETLINK_CB(request_skb).portid;
reply->skb = skb;
tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
@ -1068,11 +1113,13 @@ static int audit_set_feature(struct sk_buff *skb)
return 0;
}
static int audit_replace(pid_t pid)
static int audit_replace(struct pid *pid)
{
pid_t pvnr;
struct sk_buff *skb;
skb = audit_make_reply(0, 0, AUDIT_REPLACE, 0, 0, &pid, sizeof(pid));
pvnr = pid_vnr(pid);
skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr));
if (!skb)
return -ENOMEM;
return auditd_send_unicast_skb(skb);
@ -1102,9 +1149,9 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
memset(&s, 0, sizeof(s));
s.enabled = audit_enabled;
s.failure = audit_failure;
rcu_read_lock();
s.pid = auditd_conn.pid;
rcu_read_unlock();
/* NOTE: use pid_vnr() so the PID is relative to the current
* namespace */
s.pid = auditd_pid_vnr();
s.rate_limit = audit_rate_limit;
s.backlog_limit = audit_backlog_limit;
s.lost = atomic_read(&audit_lost);
@ -1130,51 +1177,61 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
return err;
}
if (s.mask & AUDIT_STATUS_PID) {
/* NOTE: we are using task_tgid_vnr() below because
* the s.pid value is relative to the namespace
* of the caller; at present this doesn't matter
* much since you can really only run auditd
* from the initial pid namespace, but something
* to keep in mind if this changes */
int new_pid = s.pid;
/* NOTE: we are using the vnr PID functions below
* because the s.pid value is relative to the
* namespace of the caller; at present this
* doesn't matter much since you can really only
* run auditd from the initial pid namespace, but
* something to keep in mind if this changes */
pid_t new_pid = s.pid;
pid_t auditd_pid;
pid_t requesting_pid = task_tgid_vnr(current);
struct pid *req_pid = task_tgid(current);
/* sanity check - PID values must match */
if (new_pid != pid_vnr(req_pid))
return -EINVAL;
/* test the auditd connection */
audit_replace(requesting_pid);
audit_replace(req_pid);
rcu_read_lock();
auditd_pid = auditd_conn.pid;
auditd_pid = auditd_pid_vnr();
/* only the current auditd can unregister itself */
if ((!new_pid) && (requesting_pid != auditd_pid)) {
rcu_read_unlock();
if ((!new_pid) && (new_pid != auditd_pid)) {
audit_log_config_change("audit_pid", new_pid,
auditd_pid, 0);
return -EACCES;
}
/* replacing a healthy auditd is not allowed */
if (auditd_pid && new_pid) {
rcu_read_unlock();
audit_log_config_change("audit_pid", new_pid,
auditd_pid, 0);
return -EEXIST;
}
rcu_read_unlock();
if (audit_enabled != AUDIT_OFF)
audit_log_config_change("audit_pid", new_pid,
auditd_pid, 1);
if (new_pid) {
/* register a new auditd connection */
auditd_set(new_pid,
NETLINK_CB(skb).portid,
sock_net(NETLINK_CB(skb).sk));
err = auditd_set(req_pid,
NETLINK_CB(skb).portid,
sock_net(NETLINK_CB(skb).sk));
if (audit_enabled != AUDIT_OFF)
audit_log_config_change("audit_pid",
new_pid,
auditd_pid,
err ? 0 : 1);
if (err)
return err;
/* try to process any backlog */
wake_up_interruptible(&kauditd_wait);
} else
} else {
if (audit_enabled != AUDIT_OFF)
audit_log_config_change("audit_pid",
new_pid,
auditd_pid, 1);
/* unregister the auditd connection */
auditd_reset();
}
}
if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
err = audit_set_rate_limit(s.rate_limit);
@ -1242,7 +1299,6 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
size--;
audit_log_n_untrustedstring(ab, data, size);
}
audit_set_portid(ab, NETLINK_CB(skb).portid);
audit_log_end(ab);
}
break;
@ -1256,8 +1312,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
audit_log_end(ab);
return -EPERM;
}
err = audit_rule_change(msg_type, NETLINK_CB(skb).portid,
seq, data, nlmsg_len(nlh));
err = audit_rule_change(msg_type, seq, data, nlmsg_len(nlh));
break;
case AUDIT_LIST_RULES:
err = audit_list_rules_send(skb, seq);
@ -1378,11 +1433,14 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
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.
/**
* audit_receive - receive messages from a netlink control socket
* @skb: the message buffer
*
* Parse the provided skb and deal with any messages that may be present,
* malformed skbs are discarded.
*/
static void audit_receive_skb(struct sk_buff *skb)
static void audit_receive(struct sk_buff *skb)
{
struct nlmsghdr *nlh;
/*
@ -1395,6 +1453,7 @@ static void audit_receive_skb(struct sk_buff *skb)
nlh = nlmsg_hdr(skb);
len = skb->len;
mutex_lock(&audit_cmd_mutex);
while (nlmsg_ok(nlh, len)) {
err = audit_receive_msg(skb, nlh);
/* if err or if this message says it wants a response */
@ -1403,13 +1462,6 @@ static void audit_receive_skb(struct sk_buff *skb)
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);
}
@ -1447,10 +1499,11 @@ static void __net_exit audit_net_exit(struct net *net)
{
struct audit_net *aunet = net_generic(net, audit_net_id);
rcu_read_lock();
if (net == auditd_conn.net)
auditd_reset();
rcu_read_unlock();
/* NOTE: you would think that we would want to check the auditd
* connection and potentially reset it here if it lives in this
* namespace, but since the auditd connection tracking struct holds a
* reference to this namespace (see auditd_set()) we are only ever
* going to get here after that connection has been released */
netlink_kernel_release(aunet->sk);
}
@ -1470,8 +1523,9 @@ static int __init audit_init(void)
if (audit_initialized == AUDIT_DISABLED)
return 0;
memset(&auditd_conn, 0, sizeof(auditd_conn));
spin_lock_init(&auditd_conn.lock);
audit_buffer_cache = kmem_cache_create("audit_buffer",
sizeof(struct audit_buffer),
0, SLAB_PANIC, NULL);
skb_queue_head_init(&audit_queue);
skb_queue_head_init(&audit_retry_queue);
@ -1538,60 +1592,33 @@ __setup("audit_backlog_limit=", audit_backlog_limit_set);
static void audit_buffer_free(struct audit_buffer *ab)
{
unsigned long flags;
if (!ab)
return;
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);
kmem_cache_free(audit_buffer_cache, ab);
}
static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
gfp_t gfp_mask, int type)
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;
struct audit_buffer *ab;
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 = kmem_cache_alloc(audit_buffer_cache, gfp_mask);
if (!ab)
return NULL;
ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
if (!ab->skb)
goto err;
if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
goto err;
nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
if (!nlh)
goto out_kfree_skb;
ab->ctx = ctx;
ab->gfp_mask = gfp_mask;
return ab;
out_kfree_skb:
kfree_skb(ab->skb);
ab->skb = NULL;
err:
audit_buffer_free(ab);
return NULL;
@ -1622,10 +1649,10 @@ unsigned int audit_serial(void)
}
static inline void audit_get_stamp(struct audit_context *ctx,
struct timespec *t, unsigned int *serial)
struct timespec64 *t, unsigned int *serial)
{
if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
*t = CURRENT_TIME;
ktime_get_real_ts64(t);
*serial = audit_serial();
}
}
@ -1649,7 +1676,7 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
int type)
{
struct audit_buffer *ab;
struct timespec t;
struct timespec64 t;
unsigned int uninitialized_var(serial);
if (audit_initialized != AUDIT_INITIALIZED)
@ -1702,8 +1729,8 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
}
audit_get_stamp(ab->ctx, &t, &serial);
audit_log_format(ab, "audit(%lu.%03lu:%u): ",
t.tv_sec, t.tv_nsec/1000000, serial);
audit_log_format(ab, "audit(%llu.%03lu:%u): ",
(unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial);
return ab;
}