bpf: Add bpf_prog iterator

It's mostly a copy paste of commit 6086d29def80 ("bpf: Add bpf_map iterator")
that is use to implement bpf_seq_file opreations to traverse all bpf programs.

v1->v2: Tweak to use build time btf_id

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index bae557ff2da8be6736e47477e0f482db794f85ce..72221aea1c60c0961f2805023767fbab311c9f83 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1117,6 +1117,7 @@ int  generic_map_delete_batch(struct bpf_map *map,
                              const union bpf_attr *attr,
                              union bpf_attr __user *uattr);
 struct bpf_map *bpf_map_get_curr_or_next(u32 *id);
+struct bpf_prog *bpf_prog_get_curr_or_next(u32 *id);
 
 extern int sysctl_unprivileged_bpf_disabled;
 

diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index 1131a921e1a6a062b61f0646b7ca1c684b513b9f..e6eb9c0402dabd707cf329057dbb4fb0c51fd3ae 100644 (file)
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -2,7 +2,7 @@
 obj-y := core.o
 CFLAGS_core.o += $(call cc-disable-warning, override-init)
 
-obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o bpf_iter.o map_iter.o task_iter.o
+obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o bpf_iter.o map_iter.o task_iter.o prog_iter.o
 obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o
 obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o ringbuf.o
 obj-$(CONFIG_BPF_SYSCALL) += disasm.o

diff --git a/kernel/bpf/prog_iter.c b/kernel/bpf/prog_iter.c
new file mode 100644 (file)
index 0000000..6541b57
--- /dev/null
+++ b/kernel/bpf/prog_iter.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2020 Facebook */
+#include <linux/bpf.h>
+#include <linux/fs.h>
+#include <linux/filter.h>
+#include <linux/kernel.h>
+#include <linux/btf_ids.h>
+
+struct bpf_iter_seq_prog_info {
+       u32 prog_id;
+};
+
+static void *bpf_prog_seq_start(struct seq_file *seq, loff_t *pos)
+{
+       struct bpf_iter_seq_prog_info *info = seq->private;
+       struct bpf_prog *prog;
+
+       prog = bpf_prog_get_curr_or_next(&info->prog_id);
+       if (!prog)
+               return NULL;
+
+       if (*pos == 0)
+               ++*pos;
+       return prog;
+}
+
+static void *bpf_prog_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+       struct bpf_iter_seq_prog_info *info = seq->private;
+
+       ++*pos;
+       ++info->prog_id;
+       bpf_prog_put((struct bpf_prog *)v);
+       return bpf_prog_get_curr_or_next(&info->prog_id);
+}
+
+struct bpf_iter__bpf_prog {
+       __bpf_md_ptr(struct bpf_iter_meta *, meta);
+       __bpf_md_ptr(struct bpf_prog *, prog);
+};
+
+DEFINE_BPF_ITER_FUNC(bpf_prog, struct bpf_iter_meta *meta, struct bpf_prog *prog)
+
+static int __bpf_prog_seq_show(struct seq_file *seq, void *v, bool in_stop)
+{
+       struct bpf_iter__bpf_prog ctx;
+       struct bpf_iter_meta meta;
+       struct bpf_prog *prog;
+       int ret = 0;
+
+       ctx.meta = &meta;
+       ctx.prog = v;
+       meta.seq = seq;
+       prog = bpf_iter_get_info(&meta, in_stop);
+       if (prog)
+               ret = bpf_iter_run_prog(prog, &ctx);
+
+       return ret;
+}
+
+static int bpf_prog_seq_show(struct seq_file *seq, void *v)
+{
+       return __bpf_prog_seq_show(seq, v, false);
+}
+
+static void bpf_prog_seq_stop(struct seq_file *seq, void *v)
+{
+       if (!v)
+               (void)__bpf_prog_seq_show(seq, v, true);
+       else
+               bpf_prog_put((struct bpf_prog *)v);
+}
+
+static const struct seq_operations bpf_prog_seq_ops = {
+       .start  = bpf_prog_seq_start,
+       .next   = bpf_prog_seq_next,
+       .stop   = bpf_prog_seq_stop,
+       .show   = bpf_prog_seq_show,
+};
+
+BTF_ID_LIST(btf_bpf_prog_id)
+BTF_ID(struct, bpf_prog)
+
+static struct bpf_iter_reg bpf_prog_reg_info = {
+       .target                 = "bpf_prog",
+       .seq_ops                = &bpf_prog_seq_ops,
+       .init_seq_private       = NULL,
+       .fini_seq_private       = NULL,
+       .seq_priv_size          = sizeof(struct bpf_iter_seq_prog_info),
+       .ctx_arg_info_size      = 1,
+       .ctx_arg_info           = {
+               { offsetof(struct bpf_iter__bpf_prog, prog),
+                 PTR_TO_BTF_ID_OR_NULL },
+       },
+};
+
+static int __init bpf_prog_iter_init(void)
+{
+       bpf_prog_reg_info.ctx_arg_info[0].btf_id = *btf_bpf_prog_id;
+       return bpf_iter_reg_target(&bpf_prog_reg_info);
+}
+
+late_initcall(bpf_prog_iter_init);

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index d07417d177125cf676c20f3943f19692479ace80..ee290b1f2d9ed7a1c5cc34325afb92473d5350a8 100644 (file)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3044,6 +3044,25 @@ again:
        return map;
 }
 
+struct bpf_prog *bpf_prog_get_curr_or_next(u32 *id)
+{
+       struct bpf_prog *prog;
+
+       spin_lock_bh(&prog_idr_lock);
+again:
+       prog = idr_get_next(&prog_idr, id);
+       if (prog) {
+               prog = bpf_prog_inc_not_zero(prog);
+               if (IS_ERR(prog)) {
+                       (*id)++;
+                       goto again;
+               }
+       }
+       spin_unlock_bh(&prog_idr_lock);
+
+       return prog;
+}
+
 #define BPF_PROG_GET_FD_BY_ID_LAST_FIELD prog_id
 
 struct bpf_prog *bpf_prog_by_id(u32 id)