Merge branch 'bpf-robustify'

Daniel Borkmann says:

====================
Further robustify putting BPF progs

This series addresses a potential issue reported to us by Jann Horn
with regards to putting progs. First patch moves progs generally under
RCU destruction and second patch refactors getting of progs to simplify
code a bit. For details, please see individual patches. Note, we think
that addressing this one in net-next should be sufficient.
====================

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

1 files changed, 22 insertions, 18 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index c23a4e9311b3..22863d9872b1 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -623,7 +623,7 @@ static void bpf_prog_uncharge_memlock(struct bpf_prog *prog)
 	free_uid(user);
 }
 
-static void __prog_put_common(struct rcu_head *rcu)
+static void __bpf_prog_put_rcu(struct rcu_head *rcu)
 {
 	struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu);
 
@@ -632,17 +632,10 @@ static void __prog_put_common(struct rcu_head *rcu)
 	bpf_prog_free(aux->prog);
 }
 
-/* version of bpf_prog_put() that is called after a grace period */
-void bpf_prog_put_rcu(struct bpf_prog *prog)
-{
-	if (atomic_dec_and_test(&prog->aux->refcnt))
-		call_rcu(&prog->aux->rcu, __prog_put_common);
-}
-
 void bpf_prog_put(struct bpf_prog *prog)
 {
 	if (atomic_dec_and_test(&prog->aux->refcnt))
-		__prog_put_common(&prog->aux->rcu);
+		call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);
 }
 EXPORT_SYMBOL_GPL(bpf_prog_put);
 
@@ -650,7 +643,7 @@ static int bpf_prog_release(struct inode *inode, struct file *filp)
 {
 	struct bpf_prog *prog = filp->private_data;
 
-	bpf_prog_put_rcu(prog);
+	bpf_prog_put(prog);
 	return 0;
 }
 
@@ -664,7 +657,7 @@ int bpf_prog_new_fd(struct bpf_prog *prog)
 				O_RDWR | O_CLOEXEC);
 }
 
-static struct bpf_prog *__bpf_prog_get(struct fd f)
+static struct bpf_prog *____bpf_prog_get(struct fd f)
 {
 	if (!f.file)
 		return ERR_PTR(-EBADF);
@@ -685,24 +678,35 @@ struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
 	return prog;
 }
 
-/* called by sockets/tracing/seccomp before attaching program to an event
- * pairs with bpf_prog_put()
- */
-struct bpf_prog *bpf_prog_get(u32 ufd)
+static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *type)
 {
 	struct fd f = fdget(ufd);
 	struct bpf_prog *prog;
 
-	prog = __bpf_prog_get(f);
+	prog = ____bpf_prog_get(f);
 	if (IS_ERR(prog))
 		return prog;
+	if (type && prog->type != *type) {
+		prog = ERR_PTR(-EINVAL);
+		goto out;
+	}
 
 	prog = bpf_prog_inc(prog);
+out:
 	fdput(f);
-
 	return prog;
 }
-EXPORT_SYMBOL_GPL(bpf_prog_get);
+
+struct bpf_prog *bpf_prog_get(u32 ufd)
+{
+	return __bpf_prog_get(ufd, NULL);
+}
+
+struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type)
+{
+	return __bpf_prog_get(ufd, &type);
+}
+EXPORT_SYMBOL_GPL(bpf_prog_get_type);
 
 /* last field in 'union bpf_attr' used by this command */
 #define	BPF_PROG_LOAD_LAST_FIELD kern_version