Confirm that the following sleepable prog states fail verification:
* bpf_rcu_read_unlock before bpf_spin_unlock
* RCU CS will last at least as long as spin_lock CS
Also confirm that correct usage passes verification, specifically:
* Explicit use of bpf_rcu_read_{lock, unlock} in sleepable test prog
* Implied RCU CS due to spin_lock CS
None of the selftest progs actually attach to bpf_testmod's
bpf_testmod_test_read.
Signed-off-by: Dave Marchevsky <davemarchevsky@xxxxxx>
---
.../selftests/bpf/progs/refcounted_kptr.c | 71 +++++++++++++++++++
.../bpf/progs/refcounted_kptr_fail.c | 28 ++++++++
2 files changed, 99 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/refcounted_kptr.c b/tools/testing/selftests/bpf/progs/refcounted_kptr.c
index c55652fdc63a..893a4fdb4b6e 100644
--- a/tools/testing/selftests/bpf/progs/refcounted_kptr.c
+++ b/tools/testing/selftests/bpf/progs/refcounted_kptr.c
@@ -8,6 +8,9 @@
#include "bpf_misc.h"
#include "bpf_experimental.h"
+extern void bpf_rcu_read_lock(void) __ksym;
+extern void bpf_rcu_read_unlock(void) __ksym;
+
struct node_data {
long key;
long list_data;
@@ -497,4 +500,72 @@ long rbtree_wrong_owner_remove_fail_a2(void *ctx)
return 0;
}
+SEC("?fentry.s/bpf_testmod_test_read")
+__success
+int BPF_PROG(rbtree_sleepable_rcu,
+ struct file *file, struct kobject *kobj,
+ struct bin_attribute *bin_attr, char *buf, loff_t off, size_t len)
+{
+ struct bpf_rb_node *rb;
+ struct node_data *n, *m = NULL;
+
+ n = bpf_obj_new(typeof(*n));
+ if (!n)
+ return 0;
+
+ bpf_rcu_read_lock();
+ bpf_spin_lock(&lock);
+ bpf_rbtree_add(&root, &n->r, less);
+ rb = bpf_rbtree_first(&root);
+ if (!rb)
+ goto err_out;
+
+ rb = bpf_rbtree_remove(&root, rb);
+ if (!rb)
+ goto err_out;
+
+ m = container_of(rb, struct node_data, r);
+
+err_out:
+ bpf_spin_unlock(&lock);
+ bpf_rcu_read_unlock();
+ if (m)
+ bpf_obj_drop(m);
+ return 0;
+}
+
+SEC("?fentry.s/bpf_testmod_test_read")
+__success
+int BPF_PROG(rbtree_sleepable_rcu_no_explicit_rcu_lock,
+ struct file *file, struct kobject *kobj,
+ struct bin_attribute *bin_attr, char *buf, loff_t off, size_t len)
+{
+ struct bpf_rb_node *rb;
+ struct node_data *n, *m = NULL;
+
+ n = bpf_obj_new(typeof(*n));
+ if (!n)
+ return 0;
+
+ /* No explicit bpf_rcu_read_lock */
+ bpf_spin_lock(&lock);
+ bpf_rbtree_add(&root, &n->r, less);
+ rb = bpf_rbtree_first(&root);
+ if (!rb)
+ goto err_out;
+
+ rb = bpf_rbtree_remove(&root, rb);
+ if (!rb)
+ goto err_out;
+
+ m = container_of(rb, struct node_data, r);
+
+err_out:
+ bpf_spin_unlock(&lock);
+ /* No explicit bpf_rcu_read_unlock */
+ if (m)
+ bpf_obj_drop(m);
+ return 0;
+}
+
char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c b/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c
index 0b09e5c915b1..1ef07f6ee580 100644
--- a/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c
+++ b/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c
@@ -13,6 +13,9 @@ struct node_acquire {
struct bpf_refcount refcount;
};
+extern void bpf_rcu_read_lock(void) __ksym;
+extern void bpf_rcu_read_unlock(void) __ksym;
+
#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8)))
private(A) struct bpf_spin_lock glock;
private(A) struct bpf_rb_root groot __contains(node_acquire, node);
@@ -71,4 +74,29 @@ long rbtree_refcounted_node_ref_escapes_owning_input(void *ctx)
return 0;
}
+SEC("?fentry.s/bpf_testmod_test_read")
+__failure __msg("function calls are not allowed while holding a lock")
+int BPF_PROG(rbtree_fail_sleepable_lock_across_rcu,
+ struct file *file, struct kobject *kobj,
+ struct bin_attribute *bin_attr, char *buf, loff_t off, size_t len)
+{
+ struct node_acquire *n;
+
+ n = bpf_obj_new(typeof(*n));
+ if (!n)
+ return 0;
+
+ /* spin_{lock,unlock} are in different RCU CS */
+ bpf_rcu_read_lock();
+ bpf_spin_lock(&glock);
+ bpf_rbtree_add(&groot, &n->node, less);
+ bpf_rcu_read_unlock();
+
+ bpf_rcu_read_lock();
+ bpf_spin_unlock(&glock);
+ bpf_rcu_read_unlock();
+
+ return 0;
+}
+
char _license[] SEC("license") = "GPL";
--
2.34.1
