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>

9 files changed, 34 insertions, 61 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 8411032ac90d..b3336b4f5d04 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -218,9 +218,9 @@ void bpf_register_prog_type(struct bpf_prog_type_list *tl);
 void bpf_register_map_type(struct bpf_map_type_list *tl);
 
 struct bpf_prog *bpf_prog_get(u32 ufd);
+struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type);
 struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog);
 void bpf_prog_put(struct bpf_prog *prog);
-void bpf_prog_put_rcu(struct bpf_prog *prog);
 
 struct bpf_map *bpf_map_get_with_uref(u32 ufd);
 struct bpf_map *__bpf_map_get(struct fd f);
@@ -278,11 +278,13 @@ static inline struct bpf_prog *bpf_prog_get(u32 ufd)
 	return ERR_PTR(-EOPNOTSUPP);
 }
 
-static inline void bpf_prog_put(struct bpf_prog *prog)
+static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
+						 enum bpf_prog_type type)
 {
+	return ERR_PTR(-EOPNOTSUPP);
 }
 
-static inline void bpf_prog_put_rcu(struct bpf_prog *prog)
+static inline void bpf_prog_put(struct bpf_prog *prog)
 {
 }
 #endif /* CONFIG_BPF_SYSCALL */
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 5af30732697b..4ec57a649b1f 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -390,9 +390,7 @@ static void *prog_fd_array_get_ptr(struct bpf_map *map,
 
 static void prog_fd_array_put_ptr(void *ptr)
 {
-	struct bpf_prog *prog = ptr;
-
-	bpf_prog_put_rcu(prog);
+	bpf_prog_put(ptr);
 }
 
 /* decrement refcnt of all bpf_progs that are stored in this map */
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
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 85cd41878a74..9c51ec3f0f44 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7529,7 +7529,7 @@ static void perf_event_free_bpf_prog(struct perf_event *event)
 	prog = event->tp_event->prog;
 	if (prog) {
 		event->tp_event->prog = NULL;
-		bpf_prog_put_rcu(prog);
+		bpf_prog_put(prog);
 	}
 }
 
diff --git a/net/core/filter.c b/net/core/filter.c
index 76f9a4938be4..76fee35da244 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1301,21 +1301,10 @@ int sk_reuseport_attach_filter(struct sock_fprog *fprog, struct sock *sk)
 
 static struct bpf_prog *__get_bpf(u32 ufd, struct sock *sk)
 {
-	struct bpf_prog *prog;
-
 	if (sock_flag(sk, SOCK_FILTER_LOCKED))
 		return ERR_PTR(-EPERM);
 
-	prog = bpf_prog_get(ufd);
-	if (IS_ERR(prog))
-		return prog;
-
-	if (prog->type != BPF_PROG_TYPE_SOCKET_FILTER) {
-		bpf_prog_put(prog);
-		return ERR_PTR(-EINVAL);
-	}
-
-	return prog;
+	return bpf_prog_get_type(ufd, BPF_PROG_TYPE_SOCKET_FILTER);
 }
 
 int sk_attach_bpf(u32 ufd, struct sock *sk)
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index 0b68ba730a06..cb39e05b166c 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1765,18 +1765,12 @@ static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
 	if (!csock)
 		return -ENOENT;
 
-	prog = bpf_prog_get(info->bpf_fd);
+	prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
 	if (IS_ERR(prog)) {
 		err = PTR_ERR(prog);
 		goto out;
 	}
 
-	if (prog->type != BPF_PROG_TYPE_SOCKET_FILTER) {
-		bpf_prog_put(prog);
-		err = -EINVAL;
-		goto out;
-	}
-
 	err = kcm_attach(sock, csock, prog);
 	if (err) {
 		bpf_prog_put(prog);
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index d1f3b9e977e5..48b58957adf4 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1588,13 +1588,9 @@ static int fanout_set_data_ebpf(struct packet_sock *po, char __user *data,
 	if (copy_from_user(&fd, data, len))
 		return -EFAULT;
 
-	new = bpf_prog_get(fd);
+	new = bpf_prog_get_type(fd, BPF_PROG_TYPE_SOCKET_FILTER);
 	if (IS_ERR(new))
 		return PTR_ERR(new);
-	if (new->type != BPF_PROG_TYPE_SOCKET_FILTER) {
-		bpf_prog_put(new);
-		return -EINVAL;
-	}
 
 	__fanout_set_data_bpf(po->fanout, new);
 	return 0;
diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c
index f7b6cf49ea6f..ef74bffa6101 100644
--- a/net/sched/act_bpf.c
+++ b/net/sched/act_bpf.c
@@ -223,15 +223,10 @@ static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 
 	bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
 
-	fp = bpf_prog_get(bpf_fd);
+	fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
 	if (IS_ERR(fp))
 		return PTR_ERR(fp);
 
-	if (fp->type != BPF_PROG_TYPE_SCHED_ACT) {
-		bpf_prog_put(fp);
-		return -EINVAL;
-	}
-
 	if (tb[TCA_ACT_BPF_NAME]) {
 		name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]),
 			       nla_len(tb[TCA_ACT_BPF_NAME]),
diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 7b342c779da7..c3002c2c68bb 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -272,15 +272,10 @@ static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog,
 
 	bpf_fd = nla_get_u32(tb[TCA_BPF_FD]);
 
-	fp = bpf_prog_get(bpf_fd);
+	fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_CLS);
 	if (IS_ERR(fp))
 		return PTR_ERR(fp);
 
-	if (fp->type != BPF_PROG_TYPE_SCHED_CLS) {
-		bpf_prog_put(fp);
-		return -EINVAL;
-	}
-
 	if (tb[TCA_BPF_NAME]) {
 		name = kmemdup(nla_data(tb[TCA_BPF_NAME]),
 			       nla_len(tb[TCA_BPF_NAME]),