[PATCH net-next 3/8] bpf: Add BPF_(PROG|MAP)_GET_NEXT_ID command
From: Martin KaFai Lau <hidden>
Date: 2017-05-31 00:08:40
Subsystem:
bpf [core], bpf [general] (safe dynamic programs and tools), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
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 <redacted> Acked-by: Alexei Starovoitov <redacted> Acked-by: Daniel Borkmann <daniel@iogearbox.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 94dfa9def355..e5c88f39bdc3 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 a6fe034dbc09..34dc92b3c349 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);
@@ -1067,6 +1069,34 @@ 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 = {};
@@ -1144,6 +1174,14 @@ 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;
--
2.9.3