Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Alexei Starovoitov says:

====================
pull-request: bpf-next 2019-05-31

The following pull-request contains BPF updates for your *net-next* tree.

Lots of exciting new features in the first PR of this developement cycle!
The main changes are:

1) misc verifier improvements, from Alexei.

2) bpftool can now convert btf to valid C, from Andrii.

3) verifier can insert explicit ZEXT insn when requested by 32-bit JITs.
   This feature greatly improves BPF speed on 32-bit architectures. From Jiong.

4) cgroups will now auto-detach bpf programs. This fixes issue of thousands
   bpf programs got stuck in dying cgroups. From Roman.

5) new bpf_send_signal() helper, from Yonghong.

6) cgroup inet skb programs can signal CN to the stack, from Lawrence.

7) miscellaneous cleanups, from many developers.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 88 insertions, 8 deletions

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index f92d6ad5e080..3994a231eb92 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -19,6 +19,9 @@
 #include "trace_probe.h"
 #include "trace.h"
 
+#define bpf_event_rcu_dereference(p)					\
+	rcu_dereference_protected(p, lockdep_is_held(&bpf_event_mutex))
+
 #ifdef CONFIG_MODULES
 struct bpf_trace_module {
 	struct module *module;
@@ -567,6 +570,69 @@ static const struct bpf_func_proto bpf_probe_read_str_proto = {
 	.arg3_type	= ARG_ANYTHING,
 };
 
+struct send_signal_irq_work {
+	struct irq_work irq_work;
+	struct task_struct *task;
+	u32 sig;
+};
+
+static DEFINE_PER_CPU(struct send_signal_irq_work, send_signal_work);
+
+static void do_bpf_send_signal(struct irq_work *entry)
+{
+	struct send_signal_irq_work *work;
+
+	work = container_of(entry, struct send_signal_irq_work, irq_work);
+	group_send_sig_info(work->sig, SEND_SIG_PRIV, work->task, PIDTYPE_TGID);
+}
+
+BPF_CALL_1(bpf_send_signal, u32, sig)
+{
+	struct send_signal_irq_work *work = NULL;
+
+	/* Similar to bpf_probe_write_user, task needs to be
+	 * in a sound condition and kernel memory access be
+	 * permitted in order to send signal to the current
+	 * task.
+	 */
+	if (unlikely(current->flags & (PF_KTHREAD | PF_EXITING)))
+		return -EPERM;
+	if (unlikely(uaccess_kernel()))
+		return -EPERM;
+	if (unlikely(!nmi_uaccess_okay()))
+		return -EPERM;
+
+	if (in_nmi()) {
+		/* Do an early check on signal validity. Otherwise,
+		 * the error is lost in deferred irq_work.
+		 */
+		if (unlikely(!valid_signal(sig)))
+			return -EINVAL;
+
+		work = this_cpu_ptr(&send_signal_work);
+		if (work->irq_work.flags & IRQ_WORK_BUSY)
+			return -EBUSY;
+
+		/* Add the current task, which is the target of sending signal,
+		 * to the irq_work. The current task may change when queued
+		 * irq works get executed.
+		 */
+		work->task = current;
+		work->sig = sig;
+		irq_work_queue(&work->irq_work);
+		return 0;
+	}
+
+	return group_send_sig_info(sig, SEND_SIG_PRIV, current, PIDTYPE_TGID);
+}
+
+static const struct bpf_func_proto bpf_send_signal_proto = {
+	.func		= bpf_send_signal,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_ANYTHING,
+};
+
 static const struct bpf_func_proto *
 tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
@@ -617,6 +683,8 @@ tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	case BPF_FUNC_get_current_cgroup_id:
 		return &bpf_get_current_cgroup_id_proto;
 #endif
+	case BPF_FUNC_send_signal:
+		return &bpf_send_signal_proto;
 	default:
 		return NULL;
 	}
@@ -1034,7 +1102,7 @@ static DEFINE_MUTEX(bpf_event_mutex);
 int perf_event_attach_bpf_prog(struct perf_event *event,
 			       struct bpf_prog *prog)
 {
-	struct bpf_prog_array __rcu *old_array;
+	struct bpf_prog_array *old_array;
 	struct bpf_prog_array *new_array;
 	int ret = -EEXIST;
 
@@ -1052,7 +1120,7 @@ int perf_event_attach_bpf_prog(struct perf_event *event,
 	if (event->prog)
 		goto unlock;
 
-	old_array = event->tp_event->prog_array;
+	old_array = bpf_event_rcu_dereference(event->tp_event->prog_array);
 	if (old_array &&
 	    bpf_prog_array_length(old_array) >= BPF_TRACE_MAX_PROGS) {
 		ret = -E2BIG;
@@ -1075,7 +1143,7 @@ unlock:
 
 void perf_event_detach_bpf_prog(struct perf_event *event)
 {
-	struct bpf_prog_array __rcu *old_array;
+	struct bpf_prog_array *old_array;
 	struct bpf_prog_array *new_array;
 	int ret;
 
@@ -1084,7 +1152,7 @@ void perf_event_detach_bpf_prog(struct perf_event *event)
 	if (!event->prog)
 		goto unlock;
 
-	old_array = event->tp_event->prog_array;
+	old_array = bpf_event_rcu_dereference(event->tp_event->prog_array);
 	ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array);
 	if (ret == -ENOENT)
 		goto unlock;
@@ -1106,6 +1174,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
 {
 	struct perf_event_query_bpf __user *uquery = info;
 	struct perf_event_query_bpf query = {};
+	struct bpf_prog_array *progs;
 	u32 *ids, prog_cnt, ids_len;
 	int ret;
 
@@ -1130,10 +1199,8 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
 	 */
 
 	mutex_lock(&bpf_event_mutex);
-	ret = bpf_prog_array_copy_info(event->tp_event->prog_array,
-				       ids,
-				       ids_len,
-				       &prog_cnt);
+	progs = bpf_event_rcu_dereference(event->tp_event->prog_array);
+	ret = bpf_prog_array_copy_info(progs, ids, ids_len, &prog_cnt);
 	mutex_unlock(&bpf_event_mutex);
 
 	if (copy_to_user(&uquery->prog_cnt, &prog_cnt, sizeof(prog_cnt)) ||
@@ -1343,5 +1410,18 @@ static int __init bpf_event_init(void)
 	return 0;
 }
 
+static int __init send_signal_irq_work_init(void)
+{
+	int cpu;
+	struct send_signal_irq_work *work;
+
+	for_each_possible_cpu(cpu) {
+		work = per_cpu_ptr(&send_signal_work, cpu);
+		init_irq_work(&work->irq_work, do_bpf_send_signal);
+	}
+	return 0;
+}
+
 fs_initcall(bpf_event_init);
+subsys_initcall(send_signal_irq_work_init);
 #endif /* CONFIG_MODULES */