| Message ID | 20200909182406.3147878-5-sdf@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | Allow storage of flexible metadata information for eBPF programs | expand |
On Wed, Sep 9, 2020 at 11:25 AM Stanislav Fomichev <sdf@google.com> wrote: > > From: YiFei Zhu <zhuyifei@google.com> > > Dump metadata in the 'bpftool prog' list if it's present. > For some formatting some BTF code is put directly in the > metadata dumping. Sanity checks on the map and the kind of the btf_type > to make sure we are actually dumping what we are expecting. > > A helper jsonw_reset is added to json writer so we can reuse the same > json writer without having extraneous commas. > > Sample output: > > $ bpftool prog > 6: cgroup_skb name prog tag bcf7977d3b93787c gpl > [...] > btf_id 4 > metadata: > a = "foo" > b = 1 > > $ bpftool prog --json --pretty > [{ > "id": 6, > [...] > "btf_id": 4, > "metadata": { > "a": "foo", > "b": 1 > } > } > ] > > Cc: YiFei Zhu <zhuyifei1999@gmail.com> > Signed-off-by: YiFei Zhu <zhuyifei@google.com> > Signed-off-by: Stanislav Fomichev <sdf@google.com> > --- > tools/bpf/bpftool/json_writer.c | 6 + > tools/bpf/bpftool/json_writer.h | 3 + > tools/bpf/bpftool/prog.c | 222 ++++++++++++++++++++++++++++++++ > 3 files changed, 231 insertions(+) > > diff --git a/tools/bpf/bpftool/json_writer.c b/tools/bpf/bpftool/json_writer.c > index 86501cd3c763..7fea83bedf48 100644 > --- a/tools/bpf/bpftool/json_writer.c > +++ b/tools/bpf/bpftool/json_writer.c > @@ -119,6 +119,12 @@ void jsonw_pretty(json_writer_t *self, bool on) > self->pretty = on; > } > > +void jsonw_reset(json_writer_t *self) > +{ > + assert(self->depth == 0); > + self->sep = '\0'; > +} > + > /* Basic blocks */ > static void jsonw_begin(json_writer_t *self, int c) > { > diff --git a/tools/bpf/bpftool/json_writer.h b/tools/bpf/bpftool/json_writer.h > index 35cf1f00f96c..8ace65cdb92f 100644 > --- a/tools/bpf/bpftool/json_writer.h > +++ b/tools/bpf/bpftool/json_writer.h > @@ -27,6 +27,9 @@ void jsonw_destroy(json_writer_t **self_p); > /* Cause output to have pretty whitespace */ > void jsonw_pretty(json_writer_t *self, bool on); > > +/* Reset separator to create new JSON */ > +void jsonw_reset(json_writer_t *self); > + > /* Add property name */ > void jsonw_name(json_writer_t *self, const char *name); > > diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c > index f7923414a052..ca264dc22434 100644 > --- a/tools/bpf/bpftool/prog.c > +++ b/tools/bpf/bpftool/prog.c > @@ -29,6 +29,9 @@ > #include "main.h" > #include "xlated_dumper.h" > > +#define BPF_METADATA_PREFIX "bpf_metadata_" > +#define BPF_METADATA_PREFIX_LEN strlen(BPF_METADATA_PREFIX) this is a runtime check, why not (sizeof(BPF_METADATA_PREFIX) - 1) instead? > + > const char * const prog_type_name[] = { > [BPF_PROG_TYPE_UNSPEC] = "unspec", > [BPF_PROG_TYPE_SOCKET_FILTER] = "socket_filter", > @@ -151,6 +154,221 @@ static void show_prog_maps(int fd, __u32 num_maps) > } > } > > +static int bpf_prog_find_metadata(int prog_fd, int *map_id) > +{ > + struct bpf_prog_info prog_info = {}; > + struct bpf_map_info map_info; > + __u32 prog_info_len; > + __u32 map_info_len; > + int saved_errno; > + __u32 *map_ids; > + int nr_maps; > + int map_fd; > + int ret; > + __u32 i; > + > + prog_info_len = sizeof(prog_info); > + > + ret = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &prog_info_len); > + if (ret) > + return ret; > + > + if (!prog_info.nr_map_ids) { > + errno = ENOENT; > + return -1; > + } > + > + map_ids = calloc(prog_info.nr_map_ids, sizeof(__u32)); > + if (!map_ids) { > + errno = ENOMEM; > + return -1; > + } > + > + nr_maps = prog_info.nr_map_ids; > + memset(&prog_info, 0, sizeof(prog_info)); > + prog_info.nr_map_ids = nr_maps; > + prog_info.map_ids = ptr_to_u64(map_ids); > + prog_info_len = sizeof(prog_info); > + > + ret = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &prog_info_len); > + if (ret) > + goto free_map_ids; > + > + for (i = 0; i < prog_info.nr_map_ids; i++) { > + map_fd = bpf_map_get_fd_by_id(map_ids[i]); > + if (map_fd < 0) { > + ret = -1; > + goto free_map_ids; > + } > + > + memset(&map_info, 0, sizeof(map_info)); > + map_info_len = sizeof(map_info); > + ret = bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len); > + > + saved_errno = errno; > + close(map_fd); > + errno = saved_errno; > + if (ret) > + goto free_map_ids; > + > + if (map_info.type != BPF_MAP_TYPE_ARRAY) > + continue; > + if (map_info.key_size != sizeof(int)) > + continue; > + if (map_info.max_entries != 1) > + continue; > + if (!map_info.btf_value_type_id) > + continue; > + if (!strstr(map_info.name, ".rodata")) > + continue; > + > + *map_id = map_ids[i]; > + goto free_map_ids; > + } > + > + ret = -1; > + errno = ENOENT; > + > +free_map_ids: > + saved_errno = errno; > + free(map_ids); > + errno = saved_errno; not clear why all this fussing with saving/restoring errno and then just returning 0 or -1? Just return -ENOMEM or -ENOENT as a result of this function? > + return ret; > +} > + > +static bool has_metadata_prefix(const char *s) > +{ > + return strstr(s, BPF_METADATA_PREFIX) == s; > +} > + > +static void show_prog_metadata(int fd, __u32 num_maps) > +{ > + const struct btf_type *t_datasec, *t_var; > + struct bpf_map_info map_info = {}; > + struct btf_var_secinfo *vsi; > + bool printed_header = false; > + struct btf *btf = NULL; > + unsigned int i, vlen; > + __u32 map_info_len; > + void *value = NULL; > + const char *name; > + int map_id = 0; > + int key = 0; > + int map_fd; > + int err; > + > + if (!num_maps) > + return; > + > + err = bpf_prog_find_metadata(fd, &map_id); > + if (err < 0) > + return; > + > + map_fd = bpf_map_get_fd_by_id(map_id); > + if (map_fd < 0) > + return; > + > + map_info_len = sizeof(map_info); > + err = bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len); > + if (err) > + goto out_close; > + > + value = malloc(map_info.value_size); > + if (!value) > + goto out_close; > + > + if (bpf_map_lookup_elem(map_fd, &key, value)) > + goto out_free; > + > + err = btf__get_from_id(map_info.btf_id, &btf); > + if (err || !btf) > + goto out_free; if you make bpf_prog_find_metadata() to do this value lookup and pass &info, it would probably make bpf_prog_find_metadata a bit more usable? You'll just need to ensure that callers free allocated memory. Then show_prog_metadata() would take care of processing BTF info. > + > + t_datasec = btf__type_by_id(btf, map_info.btf_value_type_id); > + if (!btf_is_datasec(t_datasec)) > + goto out_free; > + > + vlen = btf_vlen(t_datasec); > + vsi = btf_var_secinfos(t_datasec); > + > + /* We don't proceed to check the kinds of the elements of the DATASEC. > + * The verifier enforces them to be BTF_KIND_VAR. > + */ > + [...]
diff --git a/tools/bpf/bpftool/json_writer.c b/tools/bpf/bpftool/json_writer.c index 86501cd3c763..7fea83bedf48 100644 --- a/tools/bpf/bpftool/json_writer.c +++ b/tools/bpf/bpftool/json_writer.c @@ -119,6 +119,12 @@ void jsonw_pretty(json_writer_t *self, bool on) self->pretty = on; } +void jsonw_reset(json_writer_t *self) +{ + assert(self->depth == 0); + self->sep = '\0'; +} + /* Basic blocks */ static void jsonw_begin(json_writer_t *self, int c) { diff --git a/tools/bpf/bpftool/json_writer.h b/tools/bpf/bpftool/json_writer.h index 35cf1f00f96c..8ace65cdb92f 100644 --- a/tools/bpf/bpftool/json_writer.h +++ b/tools/bpf/bpftool/json_writer.h @@ -27,6 +27,9 @@ void jsonw_destroy(json_writer_t **self_p); /* Cause output to have pretty whitespace */ void jsonw_pretty(json_writer_t *self, bool on); +/* Reset separator to create new JSON */ +void jsonw_reset(json_writer_t *self); + /* Add property name */ void jsonw_name(json_writer_t *self, const char *name); diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index f7923414a052..ca264dc22434 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -29,6 +29,9 @@ #include "main.h" #include "xlated_dumper.h" +#define BPF_METADATA_PREFIX "bpf_metadata_" +#define BPF_METADATA_PREFIX_LEN strlen(BPF_METADATA_PREFIX) + const char * const prog_type_name[] = { [BPF_PROG_TYPE_UNSPEC] = "unspec", [BPF_PROG_TYPE_SOCKET_FILTER] = "socket_filter", @@ -151,6 +154,221 @@ static void show_prog_maps(int fd, __u32 num_maps) } } +static int bpf_prog_find_metadata(int prog_fd, int *map_id) +{ + struct bpf_prog_info prog_info = {}; + struct bpf_map_info map_info; + __u32 prog_info_len; + __u32 map_info_len; + int saved_errno; + __u32 *map_ids; + int nr_maps; + int map_fd; + int ret; + __u32 i; + + prog_info_len = sizeof(prog_info); + + ret = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &prog_info_len); + if (ret) + return ret; + + if (!prog_info.nr_map_ids) { + errno = ENOENT; + return -1; + } + + map_ids = calloc(prog_info.nr_map_ids, sizeof(__u32)); + if (!map_ids) { + errno = ENOMEM; + return -1; + } + + nr_maps = prog_info.nr_map_ids; + memset(&prog_info, 0, sizeof(prog_info)); + prog_info.nr_map_ids = nr_maps; + prog_info.map_ids = ptr_to_u64(map_ids); + prog_info_len = sizeof(prog_info); + + ret = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &prog_info_len); + if (ret) + goto free_map_ids; + + for (i = 0; i < prog_info.nr_map_ids; i++) { + map_fd = bpf_map_get_fd_by_id(map_ids[i]); + if (map_fd < 0) { + ret = -1; + goto free_map_ids; + } + + memset(&map_info, 0, sizeof(map_info)); + map_info_len = sizeof(map_info); + ret = bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len); + + saved_errno = errno; + close(map_fd); + errno = saved_errno; + if (ret) + goto free_map_ids; + + if (map_info.type != BPF_MAP_TYPE_ARRAY) + continue; + if (map_info.key_size != sizeof(int)) + continue; + if (map_info.max_entries != 1) + continue; + if (!map_info.btf_value_type_id) + continue; + if (!strstr(map_info.name, ".rodata")) + continue; + + *map_id = map_ids[i]; + goto free_map_ids; + } + + ret = -1; + errno = ENOENT; + +free_map_ids: + saved_errno = errno; + free(map_ids); + errno = saved_errno; + return ret; +} + +static bool has_metadata_prefix(const char *s) +{ + return strstr(s, BPF_METADATA_PREFIX) == s; +} + +static void show_prog_metadata(int fd, __u32 num_maps) +{ + const struct btf_type *t_datasec, *t_var; + struct bpf_map_info map_info = {}; + struct btf_var_secinfo *vsi; + bool printed_header = false; + struct btf *btf = NULL; + unsigned int i, vlen; + __u32 map_info_len; + void *value = NULL; + const char *name; + int map_id = 0; + int key = 0; + int map_fd; + int err; + + if (!num_maps) + return; + + err = bpf_prog_find_metadata(fd, &map_id); + if (err < 0) + return; + + map_fd = bpf_map_get_fd_by_id(map_id); + if (map_fd < 0) + return; + + map_info_len = sizeof(map_info); + err = bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len); + if (err) + goto out_close; + + value = malloc(map_info.value_size); + if (!value) + goto out_close; + + if (bpf_map_lookup_elem(map_fd, &key, value)) + goto out_free; + + err = btf__get_from_id(map_info.btf_id, &btf); + if (err || !btf) + goto out_free; + + t_datasec = btf__type_by_id(btf, map_info.btf_value_type_id); + if (!btf_is_datasec(t_datasec)) + goto out_free; + + vlen = btf_vlen(t_datasec); + vsi = btf_var_secinfos(t_datasec); + + /* We don't proceed to check the kinds of the elements of the DATASEC. + * The verifier enforces them to be BTF_KIND_VAR. + */ + + if (json_output) { + struct btf_dumper d = { + .btf = btf, + .jw = json_wtr, + .is_plain_text = false, + }; + + for (i = 0; i < vlen; i++, vsi++) { + t_var = btf__type_by_id(btf, vsi->type); + name = btf__name_by_offset(btf, t_var->name_off); + + if (!has_metadata_prefix(name)) + continue; + + if (!printed_header) { + jsonw_name(json_wtr, "metadata"); + jsonw_start_object(json_wtr); + printed_header = true; + } + + jsonw_name(json_wtr, name + BPF_METADATA_PREFIX_LEN); + err = btf_dumper_type(&d, t_var->type, value + vsi->offset); + if (err) { + p_err("btf dump failed: %d", err); + break; + } + } + if (printed_header) + jsonw_end_object(json_wtr); + } else { + json_writer_t *btf_wtr = jsonw_new(stdout); + struct btf_dumper d = { + .btf = btf, + .jw = btf_wtr, + .is_plain_text = true, + }; + if (!btf_wtr) { + p_err("jsonw alloc failed"); + goto out_free; + } + + for (i = 0; i < vlen; i++, vsi++) { + t_var = btf__type_by_id(btf, vsi->type); + name = btf__name_by_offset(btf, t_var->name_off); + + if (!has_metadata_prefix(name)) + continue; + + if (!printed_header) { + printf("\tmetadata:"); + printed_header = true; + } + + printf("\n\t\t%s = ", name + BPF_METADATA_PREFIX_LEN); + + jsonw_reset(btf_wtr); + err = btf_dumper_type(&d, t_var->type, value + vsi->offset); + if (err) { + p_err("btf dump failed: %d", err); + break; + } + } + if (printed_header) + jsonw_destroy(&btf_wtr); + } + +out_free: + btf__free(btf); + free(value); + +out_close: + close(map_fd); +} + static void print_prog_header_json(struct bpf_prog_info *info) { jsonw_uint_field(json_wtr, "id", info->id); @@ -228,6 +446,8 @@ static void print_prog_json(struct bpf_prog_info *info, int fd) emit_obj_refs_json(&refs_table, info->id, json_wtr); + show_prog_metadata(fd, info->nr_map_ids); + jsonw_end_object(json_wtr); } @@ -297,6 +517,8 @@ static void print_prog_plain(struct bpf_prog_info *info, int fd) emit_obj_refs_plain(&refs_table, info->id, "\n\tpids "); printf("\n"); + + show_prog_metadata(fd, info->nr_map_ids); } static int show_prog(int fd)