Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 317 insertions, 0 deletions

diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
new file mode 100644
index 000000000..adf6dc8a9
--- /dev/null
+++ b/net/ipv4/inetpeer.c
@@ -0,0 +1,317 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *		INETPEER - A storage for permanent information about peers
+ *
+ *  Authors:	Andrey V. Savochkin <saw@msu.ru>
+ */
+
+#include <linux/cache.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/random.h>
+#include <linux/timer.h>
+#include <linux/time.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/net.h>
+#include <linux/workqueue.h>
+#include <net/ip.h>
+#include <net/inetpeer.h>
+#include <net/secure_seq.h>
+#include <linux/siphash.h>
+
+/*
+ *  Theory of operations.
+ *  We keep one entry for each peer IP address.  The nodes contains long-living
+ *  information about the peer which doesn't depend on routes.
+ *
+ *  Nodes are removed only when reference counter goes to 0.
+ *  When it's happened the node may be removed when a sufficient amount of
+ *  time has been passed since its last use.  The less-recently-used entry can
+ *  also be removed if the pool is overloaded i.e. if the total amount of
+ *  entries is greater-or-equal than the threshold.
+ *
+ *  Node pool is organised as an RB tree.
+ *  Such an implementation has been chosen not just for fun.  It's a way to
+ *  prevent easy and efficient DoS attacks by creating hash collisions.  A huge
+ *  amount of long living nodes in a single hash slot would significantly delay
+ *  lookups performed with disabled BHs.
+ *
+ *  Serialisation issues.
+ *  1.  Nodes may appear in the tree only with the pool lock held.
+ *  2.  Nodes may disappear from the tree only with the pool lock held
+ *      AND reference count being 0.
+ *  3.  Global variable peer_total is modified under the pool lock.
+ *  4.  struct inet_peer fields modification:
+ *		rb_node: pool lock
+ *		refcnt: atomically against modifications on other CPU;
+ *		   usually under some other lock to prevent node disappearing
+ *		daddr: unchangeable
+ */
+
+static struct kmem_cache *peer_cachep __ro_after_init;
+static siphash_aligned_key_t inetpeer_hash_key __read_mostly;
+
+static u64 inetpeer_addr_hash(const struct inetpeer_addr *a)
+{
+	net_get_random_once(&inetpeer_hash_key, sizeof(inetpeer_hash_key));
+
+	if (a->family == AF_INET)
+		return siphash_2u32((__force u32)a->a4.addr, a->a4.vif,
+				    &inetpeer_hash_key);
+
+	return siphash_4u32((__force u32)a->a6.s6_addr32[0],
+			    (__force u32)a->a6.s6_addr32[1],
+			    (__force u32)a->a6.s6_addr32[2],
+			    (__force u32)a->a6.s6_addr32[3],
+			    &inetpeer_hash_key);
+}
+
+static int inetpeer_entry_cmp(u64 dhash,
+			      const struct inetpeer_addr *daddr,
+			      const struct inet_peer *p)
+{
+	if (dhash < p->hash)
+		return -1;
+	if (dhash > p->hash)
+		return 1;
+
+	return inetpeer_addr_cmp(daddr, &p->daddr);
+}
+
+void inet_peer_base_init(struct inet_peer_base *bp)
+{
+	bp->rb_root = RB_ROOT;
+	seqlock_init(&bp->lock);
+	bp->total = 0;
+}
+
+#define PEER_MAX_GC 32
+
+/* Exported for sysctl_net_ipv4.  */
+int inet_peer_threshold __read_mostly;	/* start to throw entries more
+					 * aggressively at this stage */
+int inet_peer_minttl __read_mostly = 120 * HZ;	/* TTL under high load: 120 sec */
+int inet_peer_maxttl __read_mostly = 10 * 60 * HZ;	/* usual time to live: 10 min */
+
+/* Called from ip_output.c:ip_init  */
+void __init inet_initpeers(void)
+{
+	u64 nr_entries;
+
+	 /* 1% of physical memory */
+	nr_entries = div64_ul((u64)totalram_pages() << PAGE_SHIFT,
+			      100 * L1_CACHE_ALIGN(sizeof(struct inet_peer)));
+
+	inet_peer_threshold = clamp_val(nr_entries, 4096, 65536 + 128);
+
+	peer_cachep = KMEM_CACHE(inet_peer, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
+}
+
+/* Called with rcu_read_lock() or base->lock held */
+static struct inet_peer *lookup(const struct inetpeer_addr *daddr,
+				u64 dhash,
+				struct inet_peer_base *base,
+				unsigned int seq,
+				struct inet_peer *gc_stack[],
+				unsigned int *gc_cnt,
+				struct rb_node **parent_p,
+				struct rb_node ***pp_p)
+{
+	struct rb_node **pp, *parent, *next;
+	struct inet_peer *p;
+	u32 now;
+
+	pp = &base->rb_root.rb_node;
+	parent = NULL;
+	while (1) {
+		int cmp;
+
+		next = rcu_dereference_raw(*pp);
+		if (!next)
+			break;
+		parent = next;
+		p = rb_entry(parent, struct inet_peer, rb_node);
+		cmp = inetpeer_entry_cmp(dhash, daddr, p);
+		if (cmp == 0) {
+			now = jiffies;
+			if (READ_ONCE(p->dtime) != now)
+				WRITE_ONCE(p->dtime, now);
+			return p;
+		}
+		if (gc_stack) {
+			if (*gc_cnt < PEER_MAX_GC)
+				gc_stack[(*gc_cnt)++] = p;
+		} else if (unlikely(read_seqretry(&base->lock, seq))) {
+			break;
+		}
+		if (cmp == -1)
+			pp = &next->rb_left;
+		else
+			pp = &next->rb_right;
+	}
+	*parent_p = parent;
+	*pp_p = pp;
+	return NULL;
+}
+
+/* perform garbage collect on all items stacked during a lookup */
+static void inet_peer_gc(struct inet_peer_base *base,
+			 struct inet_peer *gc_stack[],
+			 unsigned int gc_cnt)
+{
+	int peer_threshold, peer_maxttl, peer_minttl;
+	struct inet_peer *p;
+	__u32 delta, ttl;
+	int i;
+
+	peer_threshold = READ_ONCE(inet_peer_threshold);
+	peer_maxttl = READ_ONCE(inet_peer_maxttl);
+	peer_minttl = READ_ONCE(inet_peer_minttl);
+
+	if (base->total >= peer_threshold)
+		ttl = 0; /* be aggressive */
+	else
+		ttl = peer_maxttl - (peer_maxttl - peer_minttl) / HZ *
+			base->total / peer_threshold * HZ;
+	for (i = 0; i < gc_cnt; i++) {
+		p = gc_stack[i];
+
+		delta = (__u32)jiffies - READ_ONCE(p->dtime);
+
+		if (delta < ttl || !refcount_dec_if_one(&p->refcnt))
+			gc_stack[i] = NULL;
+	}
+	for (i = 0; i < gc_cnt; i++) {
+		p = gc_stack[i];
+		if (p) {
+			rb_erase(&p->rb_node, &base->rb_root);
+			base->total--;
+			kfree_rcu(p, rcu);
+		}
+	}
+}
+
+/* Must be called under RCU : No refcount change is done here. */
+struct inet_peer *inet_getpeer(struct inet_peer_base *base,
+			       const struct inetpeer_addr *daddr)
+{
+	struct inet_peer *p, *gc_stack[PEER_MAX_GC];
+	u64 dhash = inetpeer_addr_hash(daddr);
+	struct rb_node **pp, *parent;
+	unsigned int gc_cnt, seq;
+
+	/* Attempt a lockless lookup first.
+	 * Because of a concurrent writer, we might not find an existing entry.
+	 */
+	seq = read_seqbegin(&base->lock);
+	p = lookup(daddr, dhash, base, seq, NULL, &gc_cnt, &parent, &pp);
+
+	/* Make sure tree was not modified during our lookup. */
+	if (p && !read_seqretry(&base->lock, seq))
+		return p;
+
+	/* retry an exact lookup, taking the lock before.
+	 * At least, nodes should be hot in our cache.
+	 */
+	parent = NULL;
+	write_seqlock_bh(&base->lock);
+
+	gc_cnt = 0;
+	p = lookup(daddr, dhash, base, seq, gc_stack, &gc_cnt, &parent, &pp);
+	if (!p) {
+		p = kmem_cache_alloc(peer_cachep, GFP_ATOMIC);
+		if (p) {
+			p->daddr = *daddr;
+			p->hash = dhash;
+			p->dtime = (__u32)jiffies;
+			refcount_set(&p->refcnt, 1);
+			atomic_set(&p->rid, 0);
+			p->metrics[RTAX_LOCK-1] = INETPEER_METRICS_NEW;
+			p->rate_tokens = 0;
+			p->n_redirects = 0;
+			/* 60*HZ is arbitrary, but chosen enough high so that the first
+			 * calculation of tokens is at its maximum.
+			 */
+			p->rate_last = jiffies - 60*HZ;
+
+			rb_link_node(&p->rb_node, parent, pp);
+			rb_insert_color(&p->rb_node, &base->rb_root);
+			base->total++;
+		}
+	}
+	if (gc_cnt)
+		inet_peer_gc(base, gc_stack, gc_cnt);
+	write_sequnlock_bh(&base->lock);
+
+	return p;
+}
+
+void inet_putpeer(struct inet_peer *p)
+{
+	if (refcount_dec_and_test(&p->refcnt))
+		kfree_rcu(p, rcu);
+}
+
+/*
+ *	Check transmit rate limitation for given message.
+ *	The rate information is held in the inet_peer entries now.
+ *	This function is generic and could be used for other purposes
+ *	too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
+ *
+ *	Note that the same inet_peer fields are modified by functions in
+ *	route.c too, but these work for packet destinations while xrlim_allow
+ *	works for icmp destinations. This means the rate limiting information
+ *	for one "ip object" is shared - and these ICMPs are twice limited:
+ *	by source and by destination.
+ *
+ *	RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
+ *			  SHOULD allow setting of rate limits
+ *
+ * 	Shared between ICMPv4 and ICMPv6.
+ */
+#define XRLIM_BURST_FACTOR 6
+bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout)
+{
+	unsigned long now, token, otoken, delta;
+	bool rc = false;
+
+	if (!peer)
+		return true;
+
+	token = otoken = READ_ONCE(peer->rate_tokens);
+	now = jiffies;
+	delta = now - READ_ONCE(peer->rate_last);
+	if (delta) {
+		WRITE_ONCE(peer->rate_last, now);
+		token += delta;
+		if (token > XRLIM_BURST_FACTOR * timeout)
+			token = XRLIM_BURST_FACTOR * timeout;
+	}
+	if (token >= timeout) {
+		token -= timeout;
+		rc = true;
+	}
+	if (token != otoken)
+		WRITE_ONCE(peer->rate_tokens, token);
+	return rc;
+}
+
+void inetpeer_invalidate_tree(struct inet_peer_base *base)
+{
+	struct rb_node *p = rb_first(&base->rb_root);
+
+	while (p) {
+		struct inet_peer *peer = rb_entry(p, struct inet_peer, rb_node);
+
+		p = rb_next(p);
+		rb_erase(&peer->rb_node, &base->rb_root);
+		inet_putpeer(peer);
+		cond_resched();
+	}
+
+	base->total = 0;
+}