From dc4bb0e2356149aee4cdae061936f3bbdd45595c Mon Sep 17 00:00:00 2001
From: Martin KaFai Lau <kafai@fb.com>
Date: Mon, 5 Jun 2017 12:15:46 -0700
Subject: [PATCH 1/8] bpf: Introduce bpf_prog ID

This patch generates an unique ID for each BPF_PROG_LOAD-ed prog.
It is worth to note that each BPF_PROG_LOAD-ed prog will have
a different ID even they have the same bpf instructions.

The ID is generated by the existing idr_alloc_cyclic().
The ID is ranged from [1, INT_MAX).  It is allocated in cyclic manner,
so an ID will get reused every 2 billion BPF_PROG_LOAD.

The bpf_prog_alloc_id() is done after bpf_prog_select_runtime()
because the jit process may have allocated a new prog.  Hence,
we need to ensure the value of pointer 'prog' will not be changed
any more before storing the prog to the prog_idr.

After bpf_prog_select_runtime(), the prog is read-only.  Hence,
the id is stored in 'struct bpf_prog_aux'.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/linux/bpf.h  |  1 +
 kernel/bpf/syscall.c | 40 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index fcc80ca11045..c5946d19f2ca 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -172,6 +172,7 @@ struct bpf_prog_aux {
 	u32 used_map_cnt;
 	u32 max_ctx_offset;
 	u32 stack_depth;
+	u32 id;
 	struct latch_tree_node ksym_tnode;
 	struct list_head ksym_lnode;
 	const struct bpf_verifier_ops *ops;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 59da103adb85..2a1b32b470f1 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -22,8 +22,11 @@
 #include <linux/filter.h>
 #include <linux/version.h>
 #include <linux/kernel.h>
+#include <linux/idr.h>
 
 DEFINE_PER_CPU(int, bpf_prog_active);
+static DEFINE_IDR(prog_idr);
+static DEFINE_SPINLOCK(prog_idr_lock);
 
 int sysctl_unprivileged_bpf_disabled __read_mostly;
 
@@ -650,6 +653,34 @@ static void bpf_prog_uncharge_memlock(struct bpf_prog *prog)
 	free_uid(user);
 }
 
+static int bpf_prog_alloc_id(struct bpf_prog *prog)
+{
+	int id;
+
+	spin_lock_bh(&prog_idr_lock);
+	id = idr_alloc_cyclic(&prog_idr, prog, 1, INT_MAX, GFP_ATOMIC);
+	if (id > 0)
+		prog->aux->id = id;
+	spin_unlock_bh(&prog_idr_lock);
+
+	/* id is in [1, INT_MAX) */
+	if (WARN_ON_ONCE(!id))
+		return -ENOSPC;
+
+	return id > 0 ? 0 : id;
+}
+
+static void bpf_prog_free_id(struct bpf_prog *prog)
+{
+	/* cBPF to eBPF migrations are currently not in the idr store. */
+	if (!prog->aux->id)
+		return;
+
+	spin_lock_bh(&prog_idr_lock);
+	idr_remove(&prog_idr, prog->aux->id);
+	spin_unlock_bh(&prog_idr_lock);
+}
+
 static void __bpf_prog_put_rcu(struct rcu_head *rcu)
 {
 	struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu);
@@ -663,6 +694,7 @@ void bpf_prog_put(struct bpf_prog *prog)
 {
 	if (atomic_dec_and_test(&prog->aux->refcnt)) {
 		trace_bpf_prog_put_rcu(prog);
+		bpf_prog_free_id(prog);
 		bpf_prog_kallsyms_del(prog);
 		call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);
 	}
@@ -857,15 +889,21 @@ static int bpf_prog_load(union bpf_attr *attr)
 	if (err < 0)
 		goto free_used_maps;
 
+	err = bpf_prog_alloc_id(prog);
+	if (err)
+		goto free_used_maps;
+
 	err = bpf_prog_new_fd(prog);
 	if (err < 0)
 		/* failed to allocate fd */
-		goto free_used_maps;
+		goto free_id;
 
 	bpf_prog_kallsyms_add(prog);
 	trace_bpf_prog_load(prog, err);
 	return err;
 
+free_id:
+	bpf_prog_free_id(prog);
 free_used_maps:
 	free_used_maps(prog->aux);
 free_prog:

From f3f1c054c288bb6e503005e6d73611151ed20e91 Mon Sep 17 00:00:00 2001
From: Martin KaFai Lau <kafai@fb.com>
Date: Mon, 5 Jun 2017 12:15:47 -0700
Subject: [PATCH 2/8] bpf: Introduce bpf_map ID

This patch generates an unique ID for each created bpf_map.
The approach is similar to the earlier patch for bpf_prog ID.

It is worth to note that the bpf_map's ID and bpf_prog's ID
are in two independent ID spaces and both have the same valid range:
[1, INT_MAX).

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/linux/bpf.h  |  1 +
 kernel/bpf/syscall.c | 34 +++++++++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c5946d19f2ca..c32bace66d3d 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -46,6 +46,7 @@ struct bpf_map {
 	u32 max_entries;
 	u32 map_flags;
 	u32 pages;
+	u32 id;
 	struct user_struct *user;
 	const struct bpf_map_ops *ops;
 	struct work_struct work;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2a1b32b470f1..4c3075b5d840 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -27,6 +27,8 @@
 DEFINE_PER_CPU(int, bpf_prog_active);
 static DEFINE_IDR(prog_idr);
 static DEFINE_SPINLOCK(prog_idr_lock);
+static DEFINE_IDR(map_idr);
+static DEFINE_SPINLOCK(map_idr_lock);
 
 int sysctl_unprivileged_bpf_disabled __read_mostly;
 
@@ -117,6 +119,29 @@ static void bpf_map_uncharge_memlock(struct bpf_map *map)
 	free_uid(user);
 }
 
+static int bpf_map_alloc_id(struct bpf_map *map)
+{
+	int id;
+
+	spin_lock_bh(&map_idr_lock);
+	id = idr_alloc_cyclic(&map_idr, map, 1, INT_MAX, GFP_ATOMIC);
+	if (id > 0)
+		map->id = id;
+	spin_unlock_bh(&map_idr_lock);
+
+	if (WARN_ON_ONCE(!id))
+		return -ENOSPC;
+
+	return id > 0 ? 0 : id;
+}
+
+static void bpf_map_free_id(struct bpf_map *map)
+{
+	spin_lock_bh(&map_idr_lock);
+	idr_remove(&map_idr, map->id);
+	spin_unlock_bh(&map_idr_lock);
+}
+
 /* called from workqueue */
 static void bpf_map_free_deferred(struct work_struct *work)
 {
@@ -141,6 +166,7 @@ static void bpf_map_put_uref(struct bpf_map *map)
 void bpf_map_put(struct bpf_map *map)
 {
 	if (atomic_dec_and_test(&map->refcnt)) {
+		bpf_map_free_id(map);
 		INIT_WORK(&map->work, bpf_map_free_deferred);
 		schedule_work(&map->work);
 	}
@@ -239,14 +265,20 @@ static int map_create(union bpf_attr *attr)
 	if (err)
 		goto free_map_nouncharge;
 
+	err = bpf_map_alloc_id(map);
+	if (err)
+		goto free_map;
+
 	err = bpf_map_new_fd(map);
 	if (err < 0)
 		/* failed to allocate fd */
-		goto free_map;
+		goto free_id;
 
 	trace_bpf_map_create(map, err);
 	return err;
 
+free_id:
+	bpf_map_free_id(map);
 free_map:
 	bpf_map_uncharge_memlock(map);
 free_map_nouncharge:

From 34ad5580f8f9c86cb273ebea25c149613cd1667e Mon Sep 17 00:00:00 2001
From: Martin KaFai Lau <kafai@fb.com>
Date: Mon, 5 Jun 2017 12:15:48 -0700
Subject: [PATCH 3/8] bpf: Add BPF_(PROG|MAP)_GET_NEXT_ID command

This patch adds BPF_PROG_GET_NEXT_ID and BPF_MAP_GET_NEXT_ID
to allow userspace to iterate all bpf_prog IDs and bpf_map IDs.

The API is trying to be consistent with the existing
BPF_MAP_GET_NEXT_KEY.

It is currently limited to CAP_SYS_ADMIN which we can
consider to lift it in followup patches.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/uapi/linux/bpf.h |  7 +++++++
 kernel/bpf/syscall.c     | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index e78aece03628..629747a3f273 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -82,6 +82,8 @@ enum bpf_cmd {
 	BPF_PROG_ATTACH,
 	BPF_PROG_DETACH,
 	BPF_PROG_TEST_RUN,
+	BPF_PROG_GET_NEXT_ID,
+	BPF_MAP_GET_NEXT_ID,
 };
 
 enum bpf_map_type {
@@ -209,6 +211,11 @@ union bpf_attr {
 		__u32		repeat;
 		__u32		duration;
 	} test;
+
+	struct { /* anonymous struct used by BPF_*_GET_NEXT_ID */
+		__u32		start_id;
+		__u32		next_id;
+	};
 } __attribute__((aligned(8)));
 
 /* BPF helper function descriptions:
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 4c3075b5d840..2405feedb8c1 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -166,6 +166,7 @@ static void bpf_map_put_uref(struct bpf_map *map)
 void bpf_map_put(struct bpf_map *map)
 {
 	if (atomic_dec_and_test(&map->refcnt)) {
+		/* bpf_map_free_id() must be called first */
 		bpf_map_free_id(map);
 		INIT_WORK(&map->work, bpf_map_free_deferred);
 		schedule_work(&map->work);
@@ -726,6 +727,7 @@ void bpf_prog_put(struct bpf_prog *prog)
 {
 	if (atomic_dec_and_test(&prog->aux->refcnt)) {
 		trace_bpf_prog_put_rcu(prog);
+		/* bpf_prog_free_id() must be called first */
 		bpf_prog_free_id(prog);
 		bpf_prog_kallsyms_del(prog);
 		call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);
@@ -1069,6 +1071,34 @@ static int bpf_prog_test_run(const union bpf_attr *attr,
 	return ret;
 }
 
+#define BPF_OBJ_GET_NEXT_ID_LAST_FIELD next_id
+
+static int bpf_obj_get_next_id(const union bpf_attr *attr,
+			       union bpf_attr __user *uattr,
+			       struct idr *idr,
+			       spinlock_t *lock)
+{
+	u32 next_id = attr->start_id;
+	int err = 0;
+
+	if (CHECK_ATTR(BPF_OBJ_GET_NEXT_ID) || next_id >= INT_MAX)
+		return -EINVAL;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	next_id++;
+	spin_lock_bh(lock);
+	if (!idr_get_next(idr, &next_id))
+		err = -ENOENT;
+	spin_unlock_bh(lock);
+
+	if (!err)
+		err = put_user(next_id, &uattr->next_id);
+
+	return err;
+}
+
 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
 {
 	union bpf_attr attr = {};
@@ -1146,6 +1176,14 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
 	case BPF_PROG_TEST_RUN:
 		err = bpf_prog_test_run(&attr, uattr);
 		break;
+	case BPF_PROG_GET_NEXT_ID:
+		err = bpf_obj_get_next_id(&attr, uattr,
+					  &prog_idr, &prog_idr_lock);
+		break;
+	case BPF_MAP_GET_NEXT_ID:
+		err = bpf_obj_get_next_id(&attr, uattr,
+					  &map_idr, &map_idr_lock);
+		break;
 	default:
 		err = -EINVAL;
 		break;

From b16d9aa4c2b90af8d2c3201e245150f8c430c3bc Mon Sep 17 00:00:00 2001
From: Martin KaFai Lau <kafai@fb.com>
Date: Mon, 5 Jun 2017 12:15:49 -0700
Subject: [PATCH 4/8] bpf: Add BPF_PROG_GET_FD_BY_ID

Add BPF_PROG_GET_FD_BY_ID command to allow user to get a fd
from a bpf_prog's ID.

bpf_prog_inc_not_zero() is added and is called with prog_idr_lock
held.

__bpf_prog_put() is also added which has the 'bool do_idr_lock'
param to decide if the prog_idr_lock should be acquired when
freeing the prog->id.

In the error path of bpf_prog_inc_not_zero(), it may have to
call __bpf_prog_put(map, false) which does not need
to take the prog_idr_lock when freeing the prog->id.

It is currently limited to CAP_SYS_ADMIN which we can
consider to lift it in followup patches.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/uapi/linux/bpf.h |  8 +++-
 kernel/bpf/syscall.c     | 91 +++++++++++++++++++++++++++++++++++-----
 2 files changed, 87 insertions(+), 12 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 629747a3f273..d70cfed19d5e 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -84,6 +84,7 @@ enum bpf_cmd {
 	BPF_PROG_TEST_RUN,
 	BPF_PROG_GET_NEXT_ID,
 	BPF_MAP_GET_NEXT_ID,
+	BPF_PROG_GET_FD_BY_ID,
 };
 
 enum bpf_map_type {
@@ -212,8 +213,11 @@ union bpf_attr {
 		__u32		duration;
 	} test;
 
-	struct { /* anonymous struct used by BPF_*_GET_NEXT_ID */
-		__u32		start_id;
+	struct { /* anonymous struct used by BPF_*_GET_*_ID */
+		union {
+			__u32		start_id;
+			__u32		prog_id;
+		};
 		__u32		next_id;
 	};
 } __attribute__((aligned(8)));
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2405feedb8c1..dc6253bb8ebb 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -703,15 +703,23 @@ static int bpf_prog_alloc_id(struct bpf_prog *prog)
 	return id > 0 ? 0 : id;
 }
 
-static void bpf_prog_free_id(struct bpf_prog *prog)
+static void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock)
 {
 	/* cBPF to eBPF migrations are currently not in the idr store. */
 	if (!prog->aux->id)
 		return;
 
-	spin_lock_bh(&prog_idr_lock);
+	if (do_idr_lock)
+		spin_lock_bh(&prog_idr_lock);
+	else
+		__acquire(&prog_idr_lock);
+
 	idr_remove(&prog_idr, prog->aux->id);
-	spin_unlock_bh(&prog_idr_lock);
+
+	if (do_idr_lock)
+		spin_unlock_bh(&prog_idr_lock);
+	else
+		__release(&prog_idr_lock);
 }
 
 static void __bpf_prog_put_rcu(struct rcu_head *rcu)
@@ -723,16 +731,21 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu)
 	bpf_prog_free(aux->prog);
 }
 
-void bpf_prog_put(struct bpf_prog *prog)
+static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)
 {
 	if (atomic_dec_and_test(&prog->aux->refcnt)) {
 		trace_bpf_prog_put_rcu(prog);
 		/* bpf_prog_free_id() must be called first */
-		bpf_prog_free_id(prog);
+		bpf_prog_free_id(prog, do_idr_lock);
 		bpf_prog_kallsyms_del(prog);
 		call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);
 	}
 }
+
+void bpf_prog_put(struct bpf_prog *prog)
+{
+	__bpf_prog_put(prog, true);
+}
 EXPORT_SYMBOL_GPL(bpf_prog_put);
 
 static int bpf_prog_release(struct inode *inode, struct file *filp)
@@ -814,6 +827,24 @@ struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
 }
 EXPORT_SYMBOL_GPL(bpf_prog_inc);
 
+/* prog_idr_lock should have been held */
+static struct bpf_prog *bpf_prog_inc_not_zero(struct bpf_prog *prog)
+{
+	int refold;
+
+	refold = __atomic_add_unless(&prog->aux->refcnt, 1, 0);
+
+	if (refold >= BPF_MAX_REFCNT) {
+		__bpf_prog_put(prog, false);
+		return ERR_PTR(-EBUSY);
+	}
+
+	if (!refold)
+		return ERR_PTR(-ENOENT);
+
+	return prog;
+}
+
 static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *type)
 {
 	struct fd f = fdget(ufd);
@@ -928,16 +959,21 @@ static int bpf_prog_load(union bpf_attr *attr)
 		goto free_used_maps;
 
 	err = bpf_prog_new_fd(prog);
-	if (err < 0)
-		/* failed to allocate fd */
-		goto free_id;
+	if (err < 0) {
+		/* failed to allocate fd.
+		 * bpf_prog_put() is needed because the above
+		 * bpf_prog_alloc_id() has published the prog
+		 * to the userspace and the userspace may
+		 * have refcnt-ed it through BPF_PROG_GET_FD_BY_ID.
+		 */
+		bpf_prog_put(prog);
+		return err;
+	}
 
 	bpf_prog_kallsyms_add(prog);
 	trace_bpf_prog_load(prog, err);
 	return err;
 
-free_id:
-	bpf_prog_free_id(prog);
 free_used_maps:
 	free_used_maps(prog->aux);
 free_prog:
@@ -1099,6 +1135,38 @@ static int bpf_obj_get_next_id(const union bpf_attr *attr,
 	return err;
 }
 
+#define BPF_PROG_GET_FD_BY_ID_LAST_FIELD prog_id
+
+static int bpf_prog_get_fd_by_id(const union bpf_attr *attr)
+{
+	struct bpf_prog *prog;
+	u32 id = attr->prog_id;
+	int fd;
+
+	if (CHECK_ATTR(BPF_PROG_GET_FD_BY_ID))
+		return -EINVAL;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	spin_lock_bh(&prog_idr_lock);
+	prog = idr_find(&prog_idr, id);
+	if (prog)
+		prog = bpf_prog_inc_not_zero(prog);
+	else
+		prog = ERR_PTR(-ENOENT);
+	spin_unlock_bh(&prog_idr_lock);
+
+	if (IS_ERR(prog))
+		return PTR_ERR(prog);
+
+	fd = bpf_prog_new_fd(prog);
+	if (fd < 0)
+		bpf_prog_put(prog);
+
+	return fd;
+}
+
 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
 {
 	union bpf_attr attr = {};
@@ -1184,6 +1252,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
 		err = bpf_obj_get_next_id(&attr, uattr,
 					  &map_idr, &map_idr_lock);
 		break;
+	case BPF_PROG_GET_FD_BY_ID:
+		err = bpf_prog_get_fd_by_id(&attr);
+		break;
 	default:
 		err = -EINVAL;
 		break;

From bd5f5f4ecb78e2698dad655645b6d6a2f7012a8c Mon Sep 17 00:00:00 2001
From: Martin KaFai Lau <kafai@fb.com>
Date: Mon, 5 Jun 2017 12:15:50 -0700
Subject: [PATCH 5/8] bpf: Add BPF_MAP_GET_FD_BY_ID

Add BPF_MAP_GET_FD_BY_ID command to allow user to get a fd
from a bpf_map's ID.

bpf_map_inc_not_zero() is added and is called with map_idr_lock
held.

__bpf_map_put() is also added which has the 'bool do_idr_lock'
param to decide if the map_idr_lock should be acquired when
freeing the map->id.

In the error path of bpf_map_inc_not_zero(), it may have to
call __bpf_map_put(map, false) which does not need
to take the map_idr_lock when freeing the map->id.

It is currently limited to CAP_SYS_ADMIN which we can
consider to lift it in followup patches.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/uapi/linux/bpf.h |  2 +
 kernel/bpf/syscall.c     | 95 +++++++++++++++++++++++++++++++++++-----
 2 files changed, 87 insertions(+), 10 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index d70cfed19d5e..dd23f47ff00c 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -85,6 +85,7 @@ enum bpf_cmd {
 	BPF_PROG_GET_NEXT_ID,
 	BPF_MAP_GET_NEXT_ID,
 	BPF_PROG_GET_FD_BY_ID,
+	BPF_MAP_GET_FD_BY_ID,
 };
 
 enum bpf_map_type {
@@ -217,6 +218,7 @@ union bpf_attr {
 		union {
 			__u32		start_id;
 			__u32		prog_id;
+			__u32		map_id;
 		};
 		__u32		next_id;
 	};
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index dc6253bb8ebb..1802bb9c47d9 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -135,11 +135,19 @@ static int bpf_map_alloc_id(struct bpf_map *map)
 	return id > 0 ? 0 : id;
 }
 
-static void bpf_map_free_id(struct bpf_map *map)
+static void bpf_map_free_id(struct bpf_map *map, bool do_idr_lock)
 {
-	spin_lock_bh(&map_idr_lock);
+	if (do_idr_lock)
+		spin_lock_bh(&map_idr_lock);
+	else
+		__acquire(&map_idr_lock);
+
 	idr_remove(&map_idr, map->id);
-	spin_unlock_bh(&map_idr_lock);
+
+	if (do_idr_lock)
+		spin_unlock_bh(&map_idr_lock);
+	else
+		__release(&map_idr_lock);
 }
 
 /* called from workqueue */
@@ -163,16 +171,21 @@ static void bpf_map_put_uref(struct bpf_map *map)
 /* decrement map refcnt and schedule it for freeing via workqueue
  * (unrelying map implementation ops->map_free() might sleep)
  */
-void bpf_map_put(struct bpf_map *map)
+static void __bpf_map_put(struct bpf_map *map, bool do_idr_lock)
 {
 	if (atomic_dec_and_test(&map->refcnt)) {
 		/* bpf_map_free_id() must be called first */
-		bpf_map_free_id(map);
+		bpf_map_free_id(map, do_idr_lock);
 		INIT_WORK(&map->work, bpf_map_free_deferred);
 		schedule_work(&map->work);
 	}
 }
 
+void bpf_map_put(struct bpf_map *map)
+{
+	__bpf_map_put(map, true);
+}
+
 void bpf_map_put_with_uref(struct bpf_map *map)
 {
 	bpf_map_put_uref(map);
@@ -271,15 +284,20 @@ static int map_create(union bpf_attr *attr)
 		goto free_map;
 
 	err = bpf_map_new_fd(map);
-	if (err < 0)
-		/* failed to allocate fd */
-		goto free_id;
+	if (err < 0) {
+		/* failed to allocate fd.
+		 * bpf_map_put() is needed because the above
+		 * bpf_map_alloc_id() has published the map
+		 * to the userspace and the userspace may
+		 * have refcnt-ed it through BPF_MAP_GET_FD_BY_ID.
+		 */
+		bpf_map_put(map);
+		return err;
+	}
 
 	trace_bpf_map_create(map, err);
 	return err;
 
-free_id:
-	bpf_map_free_id(map);
 free_map:
 	bpf_map_uncharge_memlock(map);
 free_map_nouncharge:
@@ -331,6 +349,28 @@ struct bpf_map *bpf_map_get_with_uref(u32 ufd)
 	return map;
 }
 
+/* map_idr_lock should have been held */
+static struct bpf_map *bpf_map_inc_not_zero(struct bpf_map *map,
+					    bool uref)
+{
+	int refold;
+
+	refold = __atomic_add_unless(&map->refcnt, 1, 0);
+
+	if (refold >= BPF_MAX_REFCNT) {
+		__bpf_map_put(map, false);
+		return ERR_PTR(-EBUSY);
+	}
+
+	if (!refold)
+		return ERR_PTR(-ENOENT);
+
+	if (uref)
+		atomic_inc(&map->usercnt);
+
+	return map;
+}
+
 int __weak bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
 {
 	return -ENOTSUPP;
@@ -1167,6 +1207,38 @@ static int bpf_prog_get_fd_by_id(const union bpf_attr *attr)
 	return fd;
 }
 
+#define BPF_MAP_GET_FD_BY_ID_LAST_FIELD map_id
+
+static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
+{
+	struct bpf_map *map;
+	u32 id = attr->map_id;
+	int fd;
+
+	if (CHECK_ATTR(BPF_MAP_GET_FD_BY_ID))
+		return -EINVAL;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	spin_lock_bh(&map_idr_lock);
+	map = idr_find(&map_idr, id);
+	if (map)
+		map = bpf_map_inc_not_zero(map, true);
+	else
+		map = ERR_PTR(-ENOENT);
+	spin_unlock_bh(&map_idr_lock);
+
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	fd = bpf_map_new_fd(map);
+	if (fd < 0)
+		bpf_map_put(map);
+
+	return fd;
+}
+
 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
 {
 	union bpf_attr attr = {};
@@ -1255,6 +1327,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
 	case BPF_PROG_GET_FD_BY_ID:
 		err = bpf_prog_get_fd_by_id(&attr);
 		break;
+	case BPF_MAP_GET_FD_BY_ID:
+		err = bpf_map_get_fd_by_id(&attr);
+		break;
 	default:
 		err = -EINVAL;
 		break;

From 783d28dd11f68fb25d1f2e0de7c42336394ef128 Mon Sep 17 00:00:00 2001
From: Martin KaFai Lau <kafai@fb.com>
Date: Mon, 5 Jun 2017 12:15:51 -0700
Subject: [PATCH 6/8] bpf: Add jited_len to struct bpf_prog

Add jited_len to struct bpf_prog.  It will be
useful for the struct bpf_prog_info which will
be added in the later patch.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 arch/arm64/net/bpf_jit_comp.c     | 1 +
 arch/powerpc/net/bpf_jit_comp64.c | 1 +
 arch/s390/net/bpf_jit_comp.c      | 1 +
 arch/sparc/net/bpf_jit_comp_64.c  | 1 +
 arch/x86/net/bpf_jit_comp.c       | 1 +
 include/linux/filter.h            | 1 +
 6 files changed, 6 insertions(+)

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index b1d38eeb24f6..4f95873d7142 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -900,6 +900,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
 	bpf_jit_binary_lock_ro(header);
 	prog->bpf_func = (void *)ctx.image;
 	prog->jited = 1;
+	prog->jited_len = image_size;
 
 out_off:
 	kfree(ctx.offset);
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index a01366584a4b..861c5af1c9c4 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -1052,6 +1052,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
 
 	fp->bpf_func = (void *)image;
 	fp->jited = 1;
+	fp->jited_len = alloclen;
 
 	bpf_flush_icache(bpf_hdr, (u8 *)bpf_hdr + (bpf_hdr->pages * PAGE_SIZE));
 
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 42ad3832586c..01c6fbc3e85b 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -1329,6 +1329,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
 	bpf_jit_binary_lock_ro(header);
 	fp->bpf_func = (void *) jit.prg_buf;
 	fp->jited = 1;
+	fp->jited_len = jit.size;
 free_addrs:
 	kfree(jit.addrs);
 out:
diff --git a/arch/sparc/net/bpf_jit_comp_64.c b/arch/sparc/net/bpf_jit_comp_64.c
index 098874a81f6e..8799ae9a8788 100644
--- a/arch/sparc/net/bpf_jit_comp_64.c
+++ b/arch/sparc/net/bpf_jit_comp_64.c
@@ -1560,6 +1560,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
 
 	prog->bpf_func = (void *)ctx.image;
 	prog->jited = 1;
+	prog->jited_len = image_size;
 
 out_off:
 	kfree(ctx.offset);
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 617eac9c4511..e1324f280e06 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1167,6 +1167,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
 		bpf_jit_binary_lock_ro(header);
 		prog->bpf_func = (void *)image;
 		prog->jited = 1;
+		prog->jited_len = proglen;
 	} else {
 		prog = orig_prog;
 	}
diff --git a/include/linux/filter.h b/include/linux/filter.h
index a20ba40fcb73..1e2dddf21f3b 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -432,6 +432,7 @@ struct bpf_prog {
 	kmemcheck_bitfield_end(meta);
 	enum bpf_prog_type	type;		/* Type of BPF program */
 	u32			len;		/* Number of filter blocks */
+	u32			jited_len;	/* Size of jited insns in bytes */
 	u8			tag[BPF_TAG_SIZE];
 	struct bpf_prog_aux	*aux;		/* Auxiliary fields */
 	struct sock_fprog_kern	*orig_prog;	/* Original BPF program */

From 1e270976908686ec25fb91b8a34145be54137976 Mon Sep 17 00:00:00 2001
From: Martin KaFai Lau <kafai@fb.com>
Date: Mon, 5 Jun 2017 12:15:52 -0700
Subject: [PATCH 7/8] bpf: Add BPF_OBJ_GET_INFO_BY_FD

A single BPF_OBJ_GET_INFO_BY_FD cmd is used to obtain the info
for both bpf_prog and bpf_map.  The kernel can figure out the
fd is associated with a bpf_prog or bpf_map.

The suggested struct bpf_prog_info and struct bpf_map_info are
not meant to be a complete list and it is not the goal of this patch.
New fields can be added in the future patch.

The focus of this patch is to create the interface,
BPF_OBJ_GET_INFO_BY_FD cmd for exposing the bpf_prog's and
bpf_map's info.

The obj's info, which will be extended (and get bigger) over time, is
separated from the bpf_attr to avoid bloating the bpf_attr.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/linux/filter.h   |   2 -
 include/uapi/linux/bpf.h |  28 +++++++
 kernel/bpf/syscall.c     | 163 +++++++++++++++++++++++++++++++++++----
 3 files changed, 174 insertions(+), 19 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 1e2dddf21f3b..1fa26dc562ce 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -69,8 +69,6 @@ struct bpf_prog_aux;
 /* BPF program can access up to 512 bytes of stack space. */
 #define MAX_BPF_STACK	512
 
-#define BPF_TAG_SIZE	8
-
 /* Helper macros for filter block array initializers. */
 
 /* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index dd23f47ff00c..9b2c10b45733 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -86,6 +86,7 @@ enum bpf_cmd {
 	BPF_MAP_GET_NEXT_ID,
 	BPF_PROG_GET_FD_BY_ID,
 	BPF_MAP_GET_FD_BY_ID,
+	BPF_OBJ_GET_INFO_BY_FD,
 };
 
 enum bpf_map_type {
@@ -222,6 +223,12 @@ union bpf_attr {
 		};
 		__u32		next_id;
 	};
+
+	struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */
+		__u32		bpf_fd;
+		__u32		info_len;
+		__aligned_u64	info;
+	} info;
 } __attribute__((aligned(8)));
 
 /* BPF helper function descriptions:
@@ -686,4 +693,25 @@ struct xdp_md {
 	__u32 data_end;
 };
 
+#define BPF_TAG_SIZE	8
+
+struct bpf_prog_info {
+	__u32 type;
+	__u32 id;
+	__u8  tag[BPF_TAG_SIZE];
+	__u32 jited_prog_len;
+	__u32 xlated_prog_len;
+	__aligned_u64 jited_prog_insns;
+	__aligned_u64 xlated_prog_insns;
+} __attribute__((aligned(8)));
+
+struct bpf_map_info {
+	__u32 type;
+	__u32 id;
+	__u32 key_size;
+	__u32 value_size;
+	__u32 max_entries;
+	__u32 map_flags;
+} __attribute__((aligned(8)));
+
 #endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 1802bb9c47d9..8942c820d620 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1239,6 +1239,145 @@ static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
 	return fd;
 }
 
+static int check_uarg_tail_zero(void __user *uaddr,
+				size_t expected_size,
+				size_t actual_size)
+{
+	unsigned char __user *addr;
+	unsigned char __user *end;
+	unsigned char val;
+	int err;
+
+	if (actual_size <= expected_size)
+		return 0;
+
+	addr = uaddr + expected_size;
+	end  = uaddr + actual_size;
+
+	for (; addr < end; addr++) {
+		err = get_user(val, addr);
+		if (err)
+			return err;
+		if (val)
+			return -E2BIG;
+	}
+
+	return 0;
+}
+
+static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
+				   const union bpf_attr *attr,
+				   union bpf_attr __user *uattr)
+{
+	struct bpf_prog_info __user *uinfo = u64_to_user_ptr(attr->info.info);
+	struct bpf_prog_info info = {};
+	u32 info_len = attr->info.info_len;
+	char __user *uinsns;
+	u32 ulen;
+	int err;
+
+	err = check_uarg_tail_zero(uinfo, sizeof(info), info_len);
+	if (err)
+		return err;
+	info_len = min_t(u32, sizeof(info), info_len);
+
+	if (copy_from_user(&info, uinfo, info_len))
+		return err;
+
+	info.type = prog->type;
+	info.id = prog->aux->id;
+
+	memcpy(info.tag, prog->tag, sizeof(prog->tag));
+
+	if (!capable(CAP_SYS_ADMIN)) {
+		info.jited_prog_len = 0;
+		info.xlated_prog_len = 0;
+		goto done;
+	}
+
+	ulen = info.jited_prog_len;
+	info.jited_prog_len = prog->jited_len;
+	if (info.jited_prog_len && ulen) {
+		uinsns = u64_to_user_ptr(info.jited_prog_insns);
+		ulen = min_t(u32, info.jited_prog_len, ulen);
+		if (copy_to_user(uinsns, prog->bpf_func, ulen))
+			return -EFAULT;
+	}
+
+	ulen = info.xlated_prog_len;
+	info.xlated_prog_len = bpf_prog_size(prog->len);
+	if (info.xlated_prog_len && ulen) {
+		uinsns = u64_to_user_ptr(info.xlated_prog_insns);
+		ulen = min_t(u32, info.xlated_prog_len, ulen);
+		if (copy_to_user(uinsns, prog->insnsi, ulen))
+			return -EFAULT;
+	}
+
+done:
+	if (copy_to_user(uinfo, &info, info_len) ||
+	    put_user(info_len, &uattr->info.info_len))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int bpf_map_get_info_by_fd(struct bpf_map *map,
+				  const union bpf_attr *attr,
+				  union bpf_attr __user *uattr)
+{
+	struct bpf_map_info __user *uinfo = u64_to_user_ptr(attr->info.info);
+	struct bpf_map_info info = {};
+	u32 info_len = attr->info.info_len;
+	int err;
+
+	err = check_uarg_tail_zero(uinfo, sizeof(info), info_len);
+	if (err)
+		return err;
+	info_len = min_t(u32, sizeof(info), info_len);
+
+	info.type = map->map_type;
+	info.id = map->id;
+	info.key_size = map->key_size;
+	info.value_size = map->value_size;
+	info.max_entries = map->max_entries;
+	info.map_flags = map->map_flags;
+
+	if (copy_to_user(uinfo, &info, info_len) ||
+	    put_user(info_len, &uattr->info.info_len))
+		return -EFAULT;
+
+	return 0;
+}
+
+#define BPF_OBJ_GET_INFO_BY_FD_LAST_FIELD info.info
+
+static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
+				  union bpf_attr __user *uattr)
+{
+	int ufd = attr->info.bpf_fd;
+	struct fd f;
+	int err;
+
+	if (CHECK_ATTR(BPF_OBJ_GET_INFO_BY_FD))
+		return -EINVAL;
+
+	f = fdget(ufd);
+	if (!f.file)
+		return -EBADFD;
+
+	if (f.file->f_op == &bpf_prog_fops)
+		err = bpf_prog_get_info_by_fd(f.file->private_data, attr,
+					      uattr);
+	else if (f.file->f_op == &bpf_map_fops)
+		err = bpf_map_get_info_by_fd(f.file->private_data, attr,
+					     uattr);
+	else
+		err = -EINVAL;
+
+	fdput(f);
+	return err;
+}
+
 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
 {
 	union bpf_attr attr = {};
@@ -1258,23 +1397,10 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
 	 * user-space does not rely on any kernel feature
 	 * extensions we dont know about yet.
 	 */
-	if (size > sizeof(attr)) {
-		unsigned char __user *addr;
-		unsigned char __user *end;
-		unsigned char val;
-
-		addr = (void __user *)uattr + sizeof(attr);
-		end  = (void __user *)uattr + size;
-
-		for (; addr < end; addr++) {
-			err = get_user(val, addr);
-			if (err)
-				return err;
-			if (val)
-				return -E2BIG;
-		}
-		size = sizeof(attr);
-	}
+	err = check_uarg_tail_zero(uattr, sizeof(attr), size);
+	if (err)
+		return err;
+	size = min_t(u32, size, sizeof(attr));
 
 	/* copy attributes from user space, may be less than sizeof(bpf_attr) */
 	if (copy_from_user(&attr, uattr, size) != 0)
@@ -1330,6 +1456,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
 	case BPF_MAP_GET_FD_BY_ID:
 		err = bpf_map_get_fd_by_id(&attr);
 		break;
+	case BPF_OBJ_GET_INFO_BY_FD:
+		err = bpf_obj_get_info_by_fd(&attr, uattr);
+		break;
 	default:
 		err = -EINVAL;
 		break;

From 95b9afd3987f91c09151158279e165276a95c597 Mon Sep 17 00:00:00 2001
From: Martin KaFai Lau <kafai@fb.com>
Date: Mon, 5 Jun 2017 12:15:53 -0700
Subject: [PATCH 8/8] bpf: Test for bpf ID

Add test to exercise the bpf_prog/map id generation,
bpf_(prog|map)_get_next_id(), bpf_(prog|map)_get_fd_by_id() and
bpf_get_obj_info_by_fd().

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 tools/include/uapi/linux/bpf.h            |  41 +++++
 tools/lib/bpf/bpf.c                       |  68 ++++++++
 tools/lib/bpf/bpf.h                       |   5 +
 tools/testing/selftests/bpf/Makefile      |   2 +-
 tools/testing/selftests/bpf/test_obj_id.c |  35 ++++
 tools/testing/selftests/bpf/test_progs.c  | 191 ++++++++++++++++++++++
 6 files changed, 341 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/test_obj_id.c

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index e78aece03628..9b2c10b45733 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -82,6 +82,11 @@ enum bpf_cmd {
 	BPF_PROG_ATTACH,
 	BPF_PROG_DETACH,
 	BPF_PROG_TEST_RUN,
+	BPF_PROG_GET_NEXT_ID,
+	BPF_MAP_GET_NEXT_ID,
+	BPF_PROG_GET_FD_BY_ID,
+	BPF_MAP_GET_FD_BY_ID,
+	BPF_OBJ_GET_INFO_BY_FD,
 };
 
 enum bpf_map_type {
@@ -209,6 +214,21 @@ union bpf_attr {
 		__u32		repeat;
 		__u32		duration;
 	} test;
+
+	struct { /* anonymous struct used by BPF_*_GET_*_ID */
+		union {
+			__u32		start_id;
+			__u32		prog_id;
+			__u32		map_id;
+		};
+		__u32		next_id;
+	};
+
+	struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */
+		__u32		bpf_fd;
+		__u32		info_len;
+		__aligned_u64	info;
+	} info;
 } __attribute__((aligned(8)));
 
 /* BPF helper function descriptions:
@@ -673,4 +693,25 @@ struct xdp_md {
 	__u32 data_end;
 };
 
+#define BPF_TAG_SIZE	8
+
+struct bpf_prog_info {
+	__u32 type;
+	__u32 id;
+	__u8  tag[BPF_TAG_SIZE];
+	__u32 jited_prog_len;
+	__u32 xlated_prog_len;
+	__aligned_u64 jited_prog_insns;
+	__aligned_u64 xlated_prog_insns;
+} __attribute__((aligned(8)));
+
+struct bpf_map_info {
+	__u32 type;
+	__u32 id;
+	__u32 key_size;
+	__u32 value_size;
+	__u32 max_entries;
+	__u32 map_flags;
+} __attribute__((aligned(8)));
+
 #endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 6e178987af8e..7e0405e1651d 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -257,3 +257,71 @@ int bpf_prog_test_run(int prog_fd, int repeat, void *data, __u32 size,
 		*duration = attr.test.duration;
 	return ret;
 }
+
+int bpf_prog_get_next_id(__u32 start_id, __u32 *next_id)
+{
+	union bpf_attr attr;
+	int err;
+
+	bzero(&attr, sizeof(attr));
+	attr.start_id = start_id;
+
+	err = sys_bpf(BPF_PROG_GET_NEXT_ID, &attr, sizeof(attr));
+	if (!err)
+		*next_id = attr.next_id;
+
+	return err;
+}
+
+int bpf_map_get_next_id(__u32 start_id, __u32 *next_id)
+{
+	union bpf_attr attr;
+	int err;
+
+	bzero(&attr, sizeof(attr));
+	attr.start_id = start_id;
+
+	err = sys_bpf(BPF_MAP_GET_NEXT_ID, &attr, sizeof(attr));
+	if (!err)
+		*next_id = attr.next_id;
+
+	return err;
+}
+
+int bpf_prog_get_fd_by_id(__u32 id)
+{
+	union bpf_attr attr;
+
+	bzero(&attr, sizeof(attr));
+	attr.prog_id = id;
+
+	return sys_bpf(BPF_PROG_GET_FD_BY_ID, &attr, sizeof(attr));
+}
+
+int bpf_map_get_fd_by_id(__u32 id)
+{
+	union bpf_attr attr;
+
+	bzero(&attr, sizeof(attr));
+	attr.map_id = id;
+
+	return sys_bpf(BPF_MAP_GET_FD_BY_ID, &attr, sizeof(attr));
+}
+
+int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len)
+{
+	union bpf_attr attr;
+	int err;
+
+	bzero(&attr, sizeof(attr));
+	bzero(info, *info_len);
+	attr.info.bpf_fd = prog_fd;
+	attr.info.info_len = *info_len;
+	attr.info.info = ptr_to_u64(info);
+
+	err = sys_bpf(BPF_OBJ_GET_INFO_BY_FD, &attr, sizeof(attr));
+	if (!err)
+		*info_len = attr.info.info_len;
+
+	return err;
+}
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 972bd8333eb7..16de44a14b48 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -54,5 +54,10 @@ int bpf_prog_detach(int attachable_fd, enum bpf_attach_type type);
 int bpf_prog_test_run(int prog_fd, int repeat, void *data, __u32 size,
 		      void *data_out, __u32 *size_out, __u32 *retval,
 		      __u32 *duration);
+int bpf_prog_get_next_id(__u32 start_id, __u32 *next_id);
+int bpf_map_get_next_id(__u32 start_id, __u32 *next_id);
+int bpf_prog_get_fd_by_id(__u32 id);
+int bpf_map_get_fd_by_id(__u32 id);
+int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len);
 
 #endif
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index f389b02d43a0..9f0e07ba5334 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -14,7 +14,7 @@ LDLIBS += -lcap -lelf
 TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
 	test_align
 
-TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o
+TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o
 
 TEST_PROGS := test_kmod.sh
 
diff --git a/tools/testing/selftests/bpf/test_obj_id.c b/tools/testing/selftests/bpf/test_obj_id.c
new file mode 100644
index 000000000000..d8723aaf827a
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_obj_id.c
@@ -0,0 +1,35 @@
+/* Copyright (c) 2017 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <linux/pkt_cls.h>
+#include "bpf_helpers.h"
+
+/* It is a dumb bpf program such that it must have no
+ * issue to be loaded since testing the verifier is
+ * not the focus here.
+ */
+
+int _version SEC("version") = 1;
+
+struct bpf_map_def SEC("maps") test_map_id = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u64),
+	.max_entries = 1,
+};
+
+SEC("test_prog_id")
+int test_prog_id(struct __sk_buff *skb)
+{
+	__u32 key = 0;
+	__u64 *value;
+
+	value = bpf_map_lookup_elem(&test_map_id, &key);
+
+	return TC_ACT_OK;
+}
diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index b59f5ed4ae40..8189bfc7e277 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -22,6 +22,8 @@ typedef __u16 __sum16;
 
 #include <sys/wait.h>
 #include <sys/resource.h>
+#include <sys/types.h>
+#include <pwd.h>
 
 #include <linux/bpf.h>
 #include <linux/err.h>
@@ -70,6 +72,7 @@ static struct {
 		pass_cnt++;						\
 		printf("%s:PASS:%s %d nsec\n", __func__, tag, duration);\
 	}								\
+	__ret;								\
 })
 
 static int bpf_prog_load(const char *file, enum bpf_prog_type type,
@@ -283,6 +286,193 @@ static void test_tcp_estats(void)
 	bpf_object__close(obj);
 }
 
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64) (unsigned long) ptr;
+}
+
+static void test_bpf_obj_id(void)
+{
+	const __u64 array_magic_value = 0xfaceb00c;
+	const __u32 array_key = 0;
+	const int nr_iters = 2;
+	const char *file = "./test_obj_id.o";
+
+	struct bpf_object *objs[nr_iters];
+	int prog_fds[nr_iters], map_fds[nr_iters];
+	/* +1 to test for the info_len returned by kernel */
+	struct bpf_prog_info prog_infos[nr_iters + 1];
+	struct bpf_map_info map_infos[nr_iters + 1];
+	char jited_insns[128], xlated_insns[128];
+	__u32 i, next_id, info_len, nr_id_found, duration = 0;
+	int err = 0;
+	__u64 array_value;
+
+	err = bpf_prog_get_fd_by_id(0);
+	CHECK(err >= 0 || errno != ENOENT,
+	      "get-fd-by-notexist-prog-id", "err %d errno %d\n", err, errno);
+
+	err = bpf_map_get_fd_by_id(0);
+	CHECK(err >= 0 || errno != ENOENT,
+	      "get-fd-by-notexist-map-id", "err %d errno %d\n", err, errno);
+
+	for (i = 0; i < nr_iters; i++)
+		objs[i] = NULL;
+
+	/* Check bpf_obj_get_info_by_fd() */
+	for (i = 0; i < nr_iters; i++) {
+		err = bpf_prog_load(file, BPF_PROG_TYPE_SOCKET_FILTER,
+				    &objs[i], &prog_fds[i]);
+		/* test_obj_id.o is a dumb prog. It should never fail
+		 * to load.
+		 */
+		assert(!err);
+
+		/* Check getting prog info */
+		info_len = sizeof(struct bpf_prog_info) * 2;
+		prog_infos[i].jited_prog_insns = ptr_to_u64(jited_insns);
+		prog_infos[i].jited_prog_len = sizeof(jited_insns);
+		prog_infos[i].xlated_prog_insns = ptr_to_u64(xlated_insns);
+		prog_infos[i].xlated_prog_len = sizeof(xlated_insns);
+		err = bpf_obj_get_info_by_fd(prog_fds[i], &prog_infos[i],
+					     &info_len);
+		if (CHECK(err ||
+			  prog_infos[i].type != BPF_PROG_TYPE_SOCKET_FILTER ||
+			  info_len != sizeof(struct bpf_prog_info) ||
+			  !prog_infos[i].jited_prog_len ||
+			  !prog_infos[i].xlated_prog_len,
+			  "get-prog-info(fd)",
+			  "err %d errno %d i %d type %d(%d) info_len %u(%lu) jited_prog_len %u xlated_prog_len %u\n",
+			  err, errno, i,
+			  prog_infos[i].type, BPF_PROG_TYPE_SOCKET_FILTER,
+			  info_len, sizeof(struct bpf_prog_info),
+			  prog_infos[i].jited_prog_len,
+			  prog_infos[i].xlated_prog_len))
+			goto done;
+
+		map_fds[i] = bpf_find_map(__func__, objs[i], "test_map_id");
+		assert(map_fds[i] >= 0);
+		err = bpf_map_update_elem(map_fds[i], &array_key,
+					  &array_magic_value, 0);
+		assert(!err);
+
+		/* Check getting map info */
+		info_len = sizeof(struct bpf_map_info) * 2;
+		err = bpf_obj_get_info_by_fd(map_fds[i], &map_infos[i],
+					     &info_len);
+		if (CHECK(err ||
+			  map_infos[i].type != BPF_MAP_TYPE_ARRAY ||
+			  map_infos[i].key_size != sizeof(__u32) ||
+			  map_infos[i].value_size != sizeof(__u64) ||
+			  map_infos[i].max_entries != 1 ||
+			  map_infos[i].map_flags != 0 ||
+			  info_len != sizeof(struct bpf_map_info),
+			  "get-map-info(fd)",
+			  "err %d errno %d type %d(%d) info_len %u(%lu) key_size %u value_size %u max_entries %u map_flags %X\n",
+			  err, errno,
+			  map_infos[i].type, BPF_MAP_TYPE_ARRAY,
+			  info_len, sizeof(struct bpf_map_info),
+			  map_infos[i].key_size,
+			  map_infos[i].value_size,
+			  map_infos[i].max_entries,
+			  map_infos[i].map_flags))
+			goto done;
+	}
+
+	/* Check bpf_prog_get_next_id() */
+	nr_id_found = 0;
+	next_id = 0;
+	while (!bpf_prog_get_next_id(next_id, &next_id)) {
+		struct bpf_prog_info prog_info;
+		int prog_fd;
+
+		info_len = sizeof(prog_info);
+
+		prog_fd = bpf_prog_get_fd_by_id(next_id);
+		if (prog_fd < 0 && errno == ENOENT)
+			/* The bpf_prog is in the dead row */
+			continue;
+		if (CHECK(prog_fd < 0, "get-prog-fd(next_id)",
+			  "prog_fd %d next_id %d errno %d\n",
+			  prog_fd, next_id, errno))
+			break;
+
+		for (i = 0; i < nr_iters; i++)
+			if (prog_infos[i].id == next_id)
+				break;
+
+		if (i == nr_iters)
+			continue;
+
+		nr_id_found++;
+
+		err = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &info_len);
+		CHECK(err || info_len != sizeof(struct bpf_prog_info) ||
+		      memcmp(&prog_info, &prog_infos[i], info_len),
+		      "get-prog-info(next_id->fd)",
+		      "err %d errno %d info_len %u(%lu) memcmp %d\n",
+		      err, errno, info_len, sizeof(struct bpf_prog_info),
+		      memcmp(&prog_info, &prog_infos[i], info_len));
+
+		close(prog_fd);
+	}
+	CHECK(nr_id_found != nr_iters,
+	      "check total prog id found by get_next_id",
+	      "nr_id_found %u(%u)\n",
+	      nr_id_found, nr_iters);
+
+	/* Check bpf_map_get_next_id() */
+	nr_id_found = 0;
+	next_id = 0;
+	while (!bpf_map_get_next_id(next_id, &next_id)) {
+		struct bpf_map_info map_info;
+		int map_fd;
+
+		info_len = sizeof(map_info);
+
+		map_fd = bpf_map_get_fd_by_id(next_id);
+		if (map_fd < 0 && errno == ENOENT)
+			/* The bpf_map is in the dead row */
+			continue;
+		if (CHECK(map_fd < 0, "get-map-fd(next_id)",
+			  "map_fd %d next_id %u errno %d\n",
+			  map_fd, next_id, errno))
+			break;
+
+		for (i = 0; i < nr_iters; i++)
+			if (map_infos[i].id == next_id)
+				break;
+
+		if (i == nr_iters)
+			continue;
+
+		nr_id_found++;
+
+		err = bpf_map_lookup_elem(map_fd, &array_key, &array_value);
+		assert(!err);
+
+		err = bpf_obj_get_info_by_fd(map_fd, &map_info, &info_len);
+		CHECK(err || info_len != sizeof(struct bpf_map_info) ||
+		      memcmp(&map_info, &map_infos[i], info_len) ||
+		      array_value != array_magic_value,
+		      "check get-map-info(next_id->fd)",
+		      "err %d errno %d info_len %u(%lu) memcmp %d array_value %llu(%llu)\n",
+		      err, errno, info_len, sizeof(struct bpf_map_info),
+		      memcmp(&map_info, &map_infos[i], info_len),
+		      array_value, array_magic_value);
+
+		close(map_fd);
+	}
+	CHECK(nr_id_found != nr_iters,
+	      "check total map id found by get_next_id",
+	      "nr_id_found %u(%u)\n",
+	      nr_id_found, nr_iters);
+
+done:
+	for (i = 0; i < nr_iters; i++)
+		bpf_object__close(objs[i]);
+}
+
 int main(void)
 {
 	struct rlimit rinf = { RLIM_INFINITY, RLIM_INFINITY };
@@ -293,6 +483,7 @@ int main(void)
 	test_xdp();
 	test_l4lb();
 	test_tcp_estats();
+	test_bpf_obj_id();
 
 	printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);
 	return 0;