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The bpf iterator for map elements are implemented. The bpf program will receive four parameters: bpf_iter_meta *meta: the meta data bpf_map *map: the bpf_map whose elements are traversed void *key: the key of one element void *value: the value of the same element Here, meta and map pointers are always valid, and key has register type PTR_TO_RDONLY_BUF_OR_NULL and value has register type PTR_TO_RDWR_BUF_OR_NULL. The kernel will track the access range of key and value during verification time. Later, these values will be compared against the values in the actual map to ensure all accesses are within range. A new field iter_seq_info is added to bpf_map_ops which is used to add map type specific information, i.e., seq_ops, init/fini seq_file func and seq_file private data size. Subsequent patches will have actual implementation for bpf_map_ops->iter_seq_info. In user space, BPF_ITER_LINK_MAP_FD needs to be specified in prog attr->link_create.flags, which indicates that attr->link_create.target_fd is a map_fd. The reason for such an explicit flag is for possible future cases where one bpf iterator may allow more than one possible customization, e.g., pid and cgroup id for task_file. Current kernel internal implementation only allows the target to register at most one required bpf_iter_link_info. To support the above case, optional bpf_iter_link_info's are needed, the target can be extended to register such link infos, and user provided link_info needs to match one of target supported ones. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200723184112.590360-1-yhs@fb.com
136 lines
3.0 KiB
C
136 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (c) 2020 Facebook */
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#include <linux/bpf.h>
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#include <linux/fs.h>
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#include <linux/filter.h>
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#include <linux/kernel.h>
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#include <linux/btf_ids.h>
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struct bpf_iter_seq_map_info {
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u32 map_id;
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};
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static void *bpf_map_seq_start(struct seq_file *seq, loff_t *pos)
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{
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struct bpf_iter_seq_map_info *info = seq->private;
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struct bpf_map *map;
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map = bpf_map_get_curr_or_next(&info->map_id);
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if (!map)
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return NULL;
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if (*pos == 0)
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++*pos;
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return map;
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}
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static void *bpf_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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struct bpf_iter_seq_map_info *info = seq->private;
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++*pos;
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++info->map_id;
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bpf_map_put((struct bpf_map *)v);
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return bpf_map_get_curr_or_next(&info->map_id);
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}
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struct bpf_iter__bpf_map {
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__bpf_md_ptr(struct bpf_iter_meta *, meta);
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__bpf_md_ptr(struct bpf_map *, map);
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};
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DEFINE_BPF_ITER_FUNC(bpf_map, struct bpf_iter_meta *meta, struct bpf_map *map)
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static int __bpf_map_seq_show(struct seq_file *seq, void *v, bool in_stop)
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{
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struct bpf_iter__bpf_map ctx;
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struct bpf_iter_meta meta;
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struct bpf_prog *prog;
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int ret = 0;
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ctx.meta = &meta;
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ctx.map = v;
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meta.seq = seq;
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prog = bpf_iter_get_info(&meta, in_stop);
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if (prog)
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ret = bpf_iter_run_prog(prog, &ctx);
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return ret;
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}
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static int bpf_map_seq_show(struct seq_file *seq, void *v)
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{
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return __bpf_map_seq_show(seq, v, false);
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}
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static void bpf_map_seq_stop(struct seq_file *seq, void *v)
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{
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if (!v)
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(void)__bpf_map_seq_show(seq, v, true);
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else
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bpf_map_put((struct bpf_map *)v);
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}
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static const struct seq_operations bpf_map_seq_ops = {
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.start = bpf_map_seq_start,
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.next = bpf_map_seq_next,
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.stop = bpf_map_seq_stop,
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.show = bpf_map_seq_show,
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};
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BTF_ID_LIST(btf_bpf_map_id)
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BTF_ID(struct, bpf_map)
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static const struct bpf_iter_seq_info bpf_map_seq_info = {
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.seq_ops = &bpf_map_seq_ops,
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.init_seq_private = NULL,
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.fini_seq_private = NULL,
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.seq_priv_size = sizeof(struct bpf_iter_seq_map_info),
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};
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static struct bpf_iter_reg bpf_map_reg_info = {
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.target = "bpf_map",
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.ctx_arg_info_size = 1,
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.ctx_arg_info = {
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{ offsetof(struct bpf_iter__bpf_map, map),
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PTR_TO_BTF_ID_OR_NULL },
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},
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.seq_info = &bpf_map_seq_info,
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};
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static int bpf_iter_check_map(struct bpf_prog *prog,
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struct bpf_iter_aux_info *aux)
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{
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return -EINVAL;
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}
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DEFINE_BPF_ITER_FUNC(bpf_map_elem, struct bpf_iter_meta *meta,
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struct bpf_map *map, void *key, void *value)
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static const struct bpf_iter_reg bpf_map_elem_reg_info = {
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.target = "bpf_map_elem",
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.check_target = bpf_iter_check_map,
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.req_linfo = BPF_ITER_LINK_MAP_FD,
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.ctx_arg_info_size = 2,
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.ctx_arg_info = {
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{ offsetof(struct bpf_iter__bpf_map_elem, key),
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PTR_TO_RDONLY_BUF_OR_NULL },
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{ offsetof(struct bpf_iter__bpf_map_elem, value),
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PTR_TO_RDWR_BUF_OR_NULL },
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},
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};
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static int __init bpf_map_iter_init(void)
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{
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int ret;
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bpf_map_reg_info.ctx_arg_info[0].btf_id = *btf_bpf_map_id;
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ret = bpf_iter_reg_target(&bpf_map_reg_info);
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if (ret)
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return ret;
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return bpf_iter_reg_target(&bpf_map_elem_reg_info);
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}
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late_initcall(bpf_map_iter_init);
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