This patch introduces BPF type Format (BTF).
BTF (BPF Type Format) is the meta data format which describes
the data types of BPF program/map. Hence, it basically focus
on the C programming language which the modern BPF is primary
using. The first use case is to provide a generic pretty print
capability for a BPF map.
BTF has its root from CTF (Compact C-Type format). To simplify
the handling of BTF data, BTF removes the differences between
small and big type/struct-member. Hence, BTF consistently uses u32
instead of supporting both "one u16" and "two u32 (+padding)" in
describing type and struct-member.
It also raises the number of types (and functions) limit
from 0x7fff to 0x7fffffff.
Due to the above changes, the format is not compatible to CTF.
Hence, BTF starts with a new BTF_MAGIC and version number.
This patch does the first verification pass to the BTF. The first
pass checks:
1. meta-data size (e.g. It does not go beyond the total btf's size)
2. name_offset is valid
3. Each BTF_KIND (e.g. int, enum, struct....) does its
own check of its meta-data.
Some other checks, like checking a struct's member is referring
to a valid type, can only be done in the second pass. The second
verification pass will be implemented in the next patch.
Signed-off-by: Martin KaFai Lau <ka...@fb.com>
Acked-by: Alexei Starovoitov <a...@fb.com>
---
include/uapi/linux/btf.h | 132 +++++++
kernel/bpf/Makefile | 1 +
kernel/bpf/btf.c | 938 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 1071 insertions(+)
create mode 100644 include/uapi/linux/btf.h
create mode 100644 kernel/bpf/btf.c
diff --git a/include/uapi/linux/btf.h b/include/uapi/linux/btf.h
new file mode 100644
index 000000000000..30f23ad78eff
--- /dev/null
+++ b/include/uapi/linux/btf.h
@@ -0,0 +1,132 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* Copyright (c) 2018 Facebook */
+#ifndef _UAPI__LINUX_BTF_H__
+#define _UAPI__LINUX_BTF_H__
+
+#include <linux/types.h>
+
+#define BTF_MAGIC 0xeB9F
+#define BTF_MAGIC_SWAP 0x9FeB
+#define BTF_VERSION 1
+#define BTF_FLAGS_COMPR 0x01
+
+struct btf_header {
+ __u16 magic;
+ __u8 version;
+ __u8 flags;
+
+ __u32 parent_label;
+ __u32 parent_name;
+
+ /* All offsets are in bytes relative to the end of this header */
+ __u32 label_off; /* offset of label section */
+ __u32 object_off; /* offset of data object section*/
+ __u32 func_off; /* offset of function section */
+ __u32 type_off; /* offset of type section */
+ __u32 str_off; /* offset of string section */
+ __u32 str_len; /* length of string section */
+};
+
+/* Max # of type identifier */
+#define BTF_MAX_TYPE 0x7fffffff
+/* Max offset into the string section */
+#define BTF_MAX_NAME_OFFSET 0x7fffffff
+/* Max # of struct/union/enum members or func args */
+#define BTF_MAX_VLEN 0xffff
+
+/* The type id is referring to a parent BTF */
+#define BTF_TYPE_PARENT(id) (((id) >> 31) & 0x1)
+#define BTF_TYPE_ID(id) ((id) & BTF_MAX_TYPE)
+
+/* String is in the ELF string section */
+#define BTF_STR_TBL_ELF_ID(ref) (((ref) >> 31) & 0x1)
+#define BTF_STR_OFFSET(ref) ((ref) & BTF_MAX_NAME_OFFSET)
+
+struct btf_type {
+ __u32 name;
+ /* "info" bits arrangement
+ * bits 0-15: vlen (e.g. # of struct's members)
+ * bits 16-23: unused
+ * bits 24-28: kind (e.g. int, ptr, array...etc)
+ * bits 29-30: unused
+ * bits 31: root
+ */
+ __u32 info;
+ /* "size" is used by INT, ENUM, STRUCT and UNION.
+ * "size" tells the size of the type it is describing.
+ *
+ * "type" is used by PTR, TYPEDEF, VOLATILE, CONST and RESTRICT.
+ * "type" is a type_id referring to another type.
+ */
+ union {
+ __u32 size;
+ __u32 type;
+ };
+};
+
+#define BTF_INFO_KIND(info) (((info) >> 24) & 0x1f)
+#define BTF_INFO_ISROOT(info) (!!(((info) >> 24) & 0x80))
+#define BTF_INFO_VLEN(info) ((info) & 0xffff)
+
+#define BTF_KIND_UNKN 0 /* Unknown */
+#define BTF_KIND_INT 1 /* Integer */
+#define BTF_KIND_FLOAT 2 /* Float */
+#define BTF_KIND_PTR 3 /* Pointer */
+#define BTF_KIND_ARRAY 4 /* Array */
+#define BTF_KIND_FUNC 5 /* Function */
+#define BTF_KIND_STRUCT 6 /* Struct */
+#define BTF_KIND_UNION 7 /* Union */
+#define BTF_KIND_ENUM 8 /* Enumeration */
+#define BTF_KIND_FWD 9 /* Forward */
+#define BTF_KIND_TYPEDEF 10 /* Typedef */
+#define BTF_KIND_VOLATILE 11 /* Volatile */
+#define BTF_KIND_CONST 12 /* Const */
+#define BTF_KIND_RESTRICT 13 /* Restrict */
+#define BTF_KIND_MAX 13
+#define NR_BTF_KINDS 14
+
+/* For some specific BTF_KIND, "struct btf_type" is immediately
+ * followed by extra data.
+ */
+
+/* BTF_KIND_INT is followed by a u32 and the following
+ * is the 32 bits arrangement:
+ */
+#define BTF_INT_ENCODING(VAL) (((VAL) & 0xff000000) >> 24)
+#define BTF_INT_OFFSET(VAL) (((VAL & 0x00ff0000)) >> 16)
+#define BTF_INT_BITS(VAL) ((VAL) & 0x0000ffff)
+
+/* Attributes stored in the BTF_INT_ENCODING */
+#define BTF_INT_SIGNED 0x1
+#define BTF_INT_CHAR 0x2
+#define BTF_INT_BOOL 0x4
+#define BTF_INT_VARARGS 0x8
+
+/* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
+ * The exact number of btf_enum is stored in the vlen (of the
+ * info in "struct btf_type").
+ */
+struct btf_enum {
+ __u32 name;
+ __s32 val;
+};
+
+/* BTF_KIND_ARRAY is followed by one "struct btf_array" */
+struct btf_array {
+ __u32 type;
+ __u32 index_type;
+ __u32 nelems;
+};
+
+/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
+ * by multiple "struct btf_member". The exact number
+ * of btf_member is stored in the vlen (of the info in
+ * "struct btf_type").
+ */
+struct btf_member {
+ __u32 name;
+ __u32 type;
+ __u32 offset; /* offset in bits */
+};
+
+#endif /* _UAPI__LINUX_BTF_H__ */
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index a713fd23ec88..35c485fa9ea3 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -4,6 +4,7 @@ obj-y := core.o
obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o
obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o
bpf_lru_list.o lpm_trie.o map_in_map.o
obj-$(CONFIG_BPF_SYSCALL) += disasm.o
+obj-$(CONFIG_BPF_SYSCALL) += btf.o
ifeq ($(CONFIG_NET),y)
obj-$(CONFIG_BPF_SYSCALL) += devmap.o
obj-$(CONFIG_BPF_SYSCALL) += cpumap.o
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
new file mode 100644
index 000000000000..3a6fd0109f58
--- /dev/null
+++ b/kernel/bpf/btf.c
@@ -0,0 +1,938 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018 Facebook */
+
+#include <uapi/linux/btf.h>
+#include <uapi/linux/types.h>
+#include <linux/compiler.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/kernel.h>
+#include <linux/bpf_verifier.h>
+#include <linux/btf.h>
+
+/* BTF (BPF Type Format) is the meta data format which describes
+ * the data types of BPF program/map. Hence, it basically focus
+ * on the C programming language which the modern BPF is primary
+ * using.
+ *
+ * ELF Section:
+ * ~~~~~~~~~~~
+ * The BTF data is stored under the ".BTF" ELF section
+ *
+ * struct btf_type:
+ * ~~~~~~~~~~~~~~~
+ * Each 'struct btf_type' object describes a C data type.
+ * Depending on the type it is describing, a 'struct btf_type'
+ * object may be followed by more data. F.e.
+ * To describe an array, 'struct btf_type' is followed by
+ * 'struct btf_array'.
+ *
+ * 'struct btf_type' and any extra data following it are
+ * 4 bytes aligned.
+ *
+ * Type section:
+ * ~~~~~~~~~~~~~
+ * The BTF type section contains a list of 'struct btf_type' objects.
+ * Each one describes a C type. Recall from the above section
+ * that a 'struct btf_type' object could be immediately followed by extra
+ * data in order to desribe some particular C types.
+ *
+ * type_id:
+ * ~~~~~~~
+ * Each btf_type object is identified by a type_id. The type_id
+ * is implicitly implied by the location of the btf_type object in
+ * the BTF type section. The first one has type_id 1. The second
+ * one has type_id 2...etc. Hence, an earlier btf_type has
+ * a smaller type_id.
+ *
+ * A btf_type object may refer to another btf_type object by using
+ * type_id (i.e. the "type" in the "struct btf_type").
+ *
+ * NOTE that we cannot assume any reference-order.
+ * A btf_type object can refer to an earlier btf_type object
+ * but it can also refer to a later btf_type object.
+ *
+ * For example, to describe "const void *". A btf_type
+ * object describing "const" may refer to another btf_type
+ * object describing "void *". This type-reference is done
+ * by specifying type_id:
+ *
+ * [1] CONST (anon) type_id=2
+ * [2] PTR (anon) type_id=0
+ *
+ * The above is the btf_verifier debug log:
+ * - Each line started with "[?]" is a btf_type object
+ * - [?] is the type_id of the btf_type object.
+ * - CONST/PTR is the BTF_KIND_XXX
+ * - "(anon)" is the name of the type. It just
+ * happens that CONST and PTR has no name.
+ * - type_id=XXX is the 'u32 type' in btf_type
+ *
+ * NOTE: "void" has type_id 0
+ *
+ * String section:
+ * ~~~~~~~~~~~~~~
+ * The BTF string section contains the names used by the type section.
+ * Each string is referred by an "offset" from the beginning of the
+ * string section.
+ *
+ * Each string is '\0' terminated.
+ *
+ * The first character in the string section must be '\0'
+ * which is used to mean 'anonymous'. Some btf_type may not
+ * have a name.
+ */
+
+/* BTF verification:
+ *
+ * To verify BTF data, two passes are needed.
+ *
+ * Pass #1
+ * ~~~~~~~
+ * The first pass is to collect all btf_type objects to
+ * an array: "btf->types".
+ *
+ * Depending on the C type that a btf_type is describing,
+ * a btf_type may be followed by extra data. We don't know
+ * how many btf_type is there, and more importantly we don't
+ * know where each btf_type is located in the type section.
+ *
+ * Without knowing the location of each type_id, most verifications
+ * cannot be done. e.g. an earlier btf_type may refer to a later
+ * btf_type (recall the "const void *" above), so we cannot
+ * check this type-reference in the first pass.
+ *
+ * In the first pass, it still does some verifications (e.g.
+ * checking the name is a valid offset to the string section).
+ */
+
+#define BITS_PER_U64 (sizeof(u64) * BITS_PER_BYTE)
+#define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
+#define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
+#define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
+#define BITS_ROUNDUP_BYTES(bits) \
+ (BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))
+
+/* 16MB for 64k structs and each has 16 members and
+ * a few MB spaces for the string section.
+ * The hard limit is S32_MAX.
+ */
+#define BTF_MAX_SIZE (16 * 1024 * 1024)
+/* 64k. We can raise it later. The hard limit is S32_MAX. */
+#define BTF_MAX_NR_TYPES 65535
+
+#define for_each_member(i, struct_type, member) \
+ for (i = 0, member = btf_type_member(struct_type); \
+ i < btf_type_vlen(struct_type); \
+ i++, member++)
+
+struct btf {
+ union {
+ struct btf_header *hdr;
+ void *data;
+ };
+ struct btf_type **types;
+ const char *strings;
+ void *nohdr_data;
+ u32 nr_types;
+ u32 types_size;
+ u32 data_size;
+};
+
+struct btf_verifier_env {
+ struct btf *btf;
+ struct bpf_verifier_log log;
+ u32 log_type_id;
+};
+
+static const char * const btf_kind_str[NR_BTF_KINDS] = {
+ [BTF_KIND_UNKN] = "UNKNOWN",
+ [BTF_KIND_INT] = "INT",
+ [BTF_KIND_FLOAT] = "FLOAT",
+ [BTF_KIND_PTR] = "PTR",
+ [BTF_KIND_ARRAY] = "ARRAY",
+ [BTF_KIND_FUNC] = "FUNC",
+ [BTF_KIND_STRUCT] = "STRUCT",
+ [BTF_KIND_UNION] = "UNION",
+ [BTF_KIND_ENUM] = "ENUM",
+ [BTF_KIND_FWD] = "FWD",
+ [BTF_KIND_TYPEDEF] = "TYPEDEF",
+ [BTF_KIND_VOLATILE] = "VOLATILE",
+ [BTF_KIND_CONST] = "CONST",
+ [BTF_KIND_RESTRICT] = "RESTRICT",
+};
+
+struct btf_kind_operations {
+ s32 (*check_meta)(struct btf_verifier_env *env,
+ const struct btf_type *t,
+ u32 meta_left);
+ void (*log_details)(struct btf_verifier_env *env,
+ const struct btf_type *t);
+};
+
+static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS];
+static struct btf_type btf_void;
+
+static const char *btf_int_encoding_str(u8 encoding)
+{
+ if (encoding == 0)
+ return "(none)";
+ else if (encoding == BTF_INT_SIGNED)
+ return "SIGNED";
+ else if (encoding == BTF_INT_CHAR)
+ return "CHAR";
+ else if (encoding == BTF_INT_BOOL)
+ return "BOOL";
+ else if (encoding == BTF_INT_VARARGS)
+ return "VARARGS";
+ else
+ return "UNKN";
+}
+
+static u16 btf_type_vlen(const struct btf_type *t)
+{
+ return BTF_INFO_VLEN(t->info);
+}
+
+static u32 btf_type_int(const struct btf_type *t)
+{
+ return *(u32 *)(t + 1);
+}
+
+static const struct btf_array *btf_type_array(const struct btf_type *t)
+{
+ return (const struct btf_array *)(t + 1);
+}
+
+static const struct btf_member *btf_type_member(const struct btf_type *t)
+{
+ return (const struct btf_member *)(t + 1);
+}
+
+static const struct btf_enum *btf_type_enum(const struct btf_type *t)
+{
+ return (const struct btf_enum *)(t + 1);
+}
+
+static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
+{
+ return kind_ops[BTF_INFO_KIND(t->info)];
+}
+
+static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
+{
+ return !BTF_STR_TBL_ELF_ID(offset) &&
+ BTF_STR_OFFSET(offset) < btf->hdr->str_len;
+}
+
+static const char *btf_name_by_offset(const struct btf *btf, u32 offset)
+{
+ if (!BTF_STR_OFFSET(offset))
+ return "(anon)";
+ else if (BTF_STR_OFFSET(offset) < btf->hdr->str_len)
+ return &btf->strings[BTF_STR_OFFSET(offset)];
+ else
+ return "(invalid-name-offset)";
+}
+
+__printf(2, 3) static void __btf_verifier_log(struct bpf_verifier_log *log,
+ const char *fmt, ...)
+{
+ va_list args;
+
+ va_start(args, fmt);
+ bpf_verifier_vlog(log, fmt, args);
+ va_end(args);
+}
+
+__printf(2, 3) static void btf_verifier_log(struct btf_verifier_env *env,
+ const char *fmt, ...)
+{
+ struct bpf_verifier_log *log = &env->log;
+ va_list args;
+
+ if (!bpf_verifier_log_needed(log))
+ return;
+
+ va_start(args, fmt);
+ bpf_verifier_vlog(log, fmt, args);
+ va_end(args);
+}
+
+__printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env
*env,
+ const struct btf_type *t,
+ bool log_details,
+ const char *fmt, ...)
+{
+ struct bpf_verifier_log *log = &env->log;
+ u8 kind = BTF_INFO_KIND(t->info);
+ struct btf *btf = env->btf;
+ va_list args;
+
+ if (!bpf_verifier_log_needed(log))
+ return;
+
+ __btf_verifier_log(log, "[%u] %s %s%s",
+ env->log_type_id,
+ btf_kind_str[kind],
+ btf_name_by_offset(btf, t->name),
+ log_details ? " " : "");
+
+ if (log_details)
+ btf_type_ops(t)->log_details(env, t);
+
+ if (fmt && *fmt) {
+ __btf_verifier_log(log, " ");
+ va_start(args, fmt);
+ bpf_verifier_vlog(log, fmt, args);
+ va_end(args);
+ }
+
+ __btf_verifier_log(log, "\n");
+}
+
+#define btf_verifier_log_type(env, t, ...) \
+ __btf_verifier_log_type((env), (t), true, __VA_ARGS__)
+#define btf_verifier_log_basic(env, t, ...) \
+ __btf_verifier_log_type((env), (t), false, __VA_ARGS__)
+
+__printf(4, 5)
+static void btf_verifier_log_member(struct btf_verifier_env *env,
+ const struct btf_type *struct_type,
+ const struct btf_member *member,
+ const char *fmt, ...)
+{
+ struct bpf_verifier_log *log = &env->log;
+ struct btf *btf = env->btf;
+ va_list args;
+
+ if (!bpf_verifier_log_needed(log))
+ return;
+
+ __btf_verifier_log(log, "\t%s type_id=%u bits_offset=%u",
+ btf_name_by_offset(btf, member->name),
+ member->type, member->offset);
+
+ if (fmt && *fmt) {
+ __btf_verifier_log(log, " ");
+ va_start(args, fmt);
+ bpf_verifier_vlog(log, fmt, args);
+ va_end(args);
+ }
+
+ __btf_verifier_log(log, "\n");
+}
+
+static void btf_verifier_log_hdr(struct btf_verifier_env *env)
+{
+ struct bpf_verifier_log *log = &env->log;
+ const struct btf *btf = env->btf;
+ const struct btf_header *hdr;
+
+ if (!bpf_verifier_log_needed(log))
+ return;
+
+ hdr = btf->hdr;
+ __btf_verifier_log(log, "magic: 0x%x\n", hdr->magic);
+ __btf_verifier_log(log, "version: %u\n", hdr->version);
+ __btf_verifier_log(log, "flags: 0x%x\n", hdr->flags);
+ __btf_verifier_log(log, "parent_label: %u\n", hdr->parent_label);
+ __btf_verifier_log(log, "parent_name: %u\n", hdr->parent_name);
+ __btf_verifier_log(log, "label_off: %u\n", hdr->label_off);
+ __btf_verifier_log(log, "object_off: %u\n", hdr->object_off);
+ __btf_verifier_log(log, "func_off: %u\n", hdr->func_off);
+ __btf_verifier_log(log, "type_off: %u\n", hdr->type_off);
+ __btf_verifier_log(log, "str_off: %u\n", hdr->str_off);
+ __btf_verifier_log(log, "str_len: %u\n", hdr->str_len);
+ __btf_verifier_log(log, "btf_total_size: %u\n", btf->data_size);
+}
+
+static int btf_add_type(struct btf_verifier_env *env, struct btf_type *t)
+{
+ struct btf *btf = env->btf;
+
+ /* < 2 because +1 for btf_void which is always in btf->types[0].
+ * btf_void is not accounted in btf->nr_types because btf_void
+ * does not come from the BTF file.
+ */
+ if (btf->types_size - btf->nr_types < 2) {
+ /* Expand 'types' array */
+
+ struct btf_type **new_types;
+ u32 expand_by, new_size;
+
+ if (btf->types_size == BTF_MAX_NR_TYPES) {
+ btf_verifier_log(env, "Exceeded max num of types");
+ return -E2BIG;
+ }
+
+ expand_by = max_t(u32, btf->types_size >> 2, 16);
+ new_size = min_t(u32, BTF_MAX_NR_TYPES,
+ btf->types_size + expand_by);
+
+ new_types = kvzalloc(new_size * sizeof(*new_types),
+ GFP_KERNEL | __GFP_NOWARN);
+ if (!new_types)
+ return -ENOMEM;
+
+ if (btf->nr_types == 0)
+ new_types[0] = &btf_void;
+ else
+ memcpy(new_types, btf->types,
+ sizeof(*btf->types) * (btf->nr_types + 1));
+
+ kvfree(btf->types);
+ btf->types = new_types;
+ btf->types_size = new_size;
+ }
+
+ btf->types[++(btf->nr_types)] = t;
+
+ return 0;
+}
+
+static void btf_free(struct btf *btf)
+{
+ kvfree(btf->types);
+ kvfree(btf->data);
+ kfree(btf);
+}
+
+static void btf_verifier_env_free(struct btf_verifier_env *env)
+{
+ kfree(env);
+}
+
+static int btf_df_check_meta(struct btf_verifier_env *env,
+ const struct btf_type *t,
+ u32 meta_left)
+{
+ btf_verifier_log_basic(env, t, "Unsupported check_meta");
+ return -ENOTSUPP;
+}
+
+static void btf_df_log(struct btf_verifier_env *env,
+ const struct btf_type *t)
+{
+ btf_verifier_log(env, "Unsupported log_details");
+}
+
+static struct btf_kind_operations df_ops = {
+ .check_meta = btf_df_check_meta,
+ .log_details = btf_df_log,
+};
+
+static s32 btf_int_check_meta(struct btf_verifier_env *env,
+ const struct btf_type *t,
+ u32 meta_left)
+{
+ u32 int_data, nr_bits, meta_needed = sizeof(int_data);
+ u16 encoding;
+
+ if (meta_left < meta_needed) {
+ btf_verifier_log_basic(env, t,
+ "meta_left:%u meta_needed:%u",
+ meta_left, meta_needed);
+ return -EINVAL;
+ }
+
+ if (btf_type_vlen(t)) {
+ btf_verifier_log_type(env, t, "vlen != 0");
+ return -EINVAL;
+ }
+
+ int_data = btf_type_int(t);
+ nr_bits = BTF_INT_BITS(int_data) + BTF_INT_OFFSET(int_data);
+
+ if (nr_bits > BITS_PER_U64) {
+ btf_verifier_log_type(env, t, "nr_bits exceeds %zu",
+ BITS_PER_U64);
+ return -EINVAL;
+ }
+
+ if (BITS_ROUNDUP_BYTES(nr_bits) > t->size) {
+ btf_verifier_log_type(env, t, "nr_bits exceeds type_size");
+ return -EINVAL;
+ }
+
+ encoding = BTF_INT_ENCODING(int_data);
+ if (encoding &&
+ encoding != BTF_INT_SIGNED &&
+ encoding != BTF_INT_CHAR &&
+ encoding != BTF_INT_BOOL &&
+ encoding != BTF_INT_VARARGS) {
+ btf_verifier_log_type(env, t, "Unsupported encoding");
+ return -ENOTSUPP;
+ }
+
+ btf_verifier_log_type(env, t, NULL);
+
+ return meta_needed;
+}
+
+static void btf_int_log(struct btf_verifier_env *env,
+ const struct btf_type *t)
+{
+ int int_data = btf_type_int(t);
+
+ btf_verifier_log(env,
+ "size=%u bits_offset=%u nr_bits=%u encoding=%s",
+ t->size, BTF_INT_OFFSET(int_data),
+ BTF_INT_BITS(int_data),
+ btf_int_encoding_str(BTF_INT_ENCODING(int_data)));
+}
+
+static const struct btf_kind_operations int_ops = {
+ .check_meta = btf_int_check_meta,
+ .log_details = btf_int_log,
+};
+
+static int btf_ref_type_check_meta(struct btf_verifier_env *env,
+ const struct btf_type *t,
+ u32 meta_left)
+{
+ if (btf_type_vlen(t)) {
+ btf_verifier_log_type(env, t, "vlen != 0");
+ return -EINVAL;
+ }
+
+ if (BTF_TYPE_PARENT(t->type)) {
+ btf_verifier_log_type(env, t, "Invalid type_id");
+ return -EINVAL;
+ }
+
+ btf_verifier_log_type(env, t, NULL);
+
+ return 0;
+}
+
+static void btf_ref_type_log(struct btf_verifier_env *env,
+ const struct btf_type *t)
+{
+ btf_verifier_log(env, "type_id=%u", t->type);
+}
+
+static struct btf_kind_operations modifier_ops = {
+ .check_meta = btf_ref_type_check_meta,
+ .log_details = btf_ref_type_log,
+};
+
+static struct btf_kind_operations ptr_ops = {
+ .check_meta = btf_ref_type_check_meta,
+ .log_details = btf_ref_type_log,
+};
+
+static struct btf_kind_operations fwd_ops = {
+ .check_meta = btf_ref_type_check_meta,
+ .log_details = btf_ref_type_log,
+};
+
+static s32 btf_array_check_meta(struct btf_verifier_env *env,
+ const struct btf_type *t,
+ u32 meta_left)
+{
+ const struct btf_array *array = btf_type_array(t);
+ u32 meta_needed = sizeof(*array);
+
+ if (meta_left < meta_needed) {
+ btf_verifier_log_basic(env, t,
+ "meta_left:%u meta_needed:%u",
+ meta_left, meta_needed);
+ return -EINVAL;
+ }
+
+ if (btf_type_vlen(t)) {
+ btf_verifier_log_type(env, t, "vlen != 0");
+ return -EINVAL;
+ }
+
+ /* We are a little forgiving on array->index_type since
+ * the kernel is not using it.
+ */
+ /* Array elem cannot be in type void,
+ * so !array->type is not allowed.
+ */
+ if (!array->type || BTF_TYPE_PARENT(array->type)) {
+ btf_verifier_log_type(env, t, "Invalid type_id");
+ return -EINVAL;
+ }
+
+ btf_verifier_log_type(env, t, NULL);
+
+ return meta_needed;
+}
+
+static void btf_array_log(struct btf_verifier_env *env,
+ const struct btf_type *t)
+{
+ const struct btf_array *array = btf_type_array(t);
+
+ btf_verifier_log(env, "type_id=%u index_type_id=%u nr_elems=%u",
+ array->type, array->index_type, array->nelems);
+}
+
+static struct btf_kind_operations array_ops = {
+ .check_meta = btf_array_check_meta,
+ .log_details = btf_array_log,
+};
+
+static s32 btf_struct_check_meta(struct btf_verifier_env *env,
+ const struct btf_type *t,
+ u32 meta_left)
+{
+ bool is_union = BTF_INFO_KIND(t->info) == BTF_KIND_UNION;
+ const struct btf_member *member;
+ struct btf *btf = env->btf;
+ u32 struct_size = t->size;
+ u32 meta_needed;
+ u16 i;
+
+ meta_needed = btf_type_vlen(t) * sizeof(*member);
+ if (meta_left < meta_needed) {
+ btf_verifier_log_basic(env, t,
+ "meta_left:%u meta_needed:%u",
+ meta_left, meta_needed);
+ return -EINVAL;
+ }
+
+ btf_verifier_log_type(env, t, NULL);
+
+ for_each_member(i, t, member) {
+ if (!btf_name_offset_valid(btf, member->name)) {
+ btf_verifier_log_member(env, t, member,
+ "Invalid member name_offset:%u",
+ member->name);
+ return -EINVAL;
+ }
+
+ /* A member cannot be in type void */
+ if (!member->type || BTF_TYPE_PARENT(member->type)) {
+ btf_verifier_log_member(env, t, member,
+ "Invalid type_id");
+ return -EINVAL;
+ }
+
+ if (is_union && member->offset) {
+ btf_verifier_log_member(env, t, member,
+ "Invalid member bits_offset");
+ return -EINVAL;
+ }
+
+ if (BITS_ROUNDUP_BYTES(member->offset) > struct_size) {
+ btf_verifier_log_member(env, t, member,
+ "Memmber bits_offset exceeds
its struct size");
+ return -EINVAL;
+ }
+
+ btf_verifier_log_member(env, t, member, NULL);
+ }
+
+ return meta_needed;
+}
+
+static void btf_struct_log(struct btf_verifier_env *env,
+ const struct btf_type *t)
+{
+ btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
+}
+
+static struct btf_kind_operations struct_ops = {
+ .check_meta = btf_struct_check_meta,
+ .log_details = btf_struct_log,
+};
+
+static s32 btf_enum_check_meta(struct btf_verifier_env *env,
+ const struct btf_type *t,
+ u32 meta_left)
+{
+ const struct btf_enum *enums = btf_type_enum(t);
+ struct btf *btf = env->btf;
+ u16 i, nr_enums;
+ u32 meta_needed;
+
+ nr_enums = btf_type_vlen(t);
+ meta_needed = nr_enums * sizeof(*enums);
+
+ if (meta_left < meta_needed) {
+ btf_verifier_log_basic(env, t,
+ "meta_left:%u meta_needed:%u",
+ meta_left, meta_needed);
+ return -EINVAL;
+ }
+
+ if (t->size != sizeof(int)) {
+ btf_verifier_log_type(env, t, "Expected size:%zu",
+ sizeof(int));
+ return -EINVAL;
+ }
+
+ btf_verifier_log_type(env, t, NULL);
+
+ for (i = 0; i < nr_enums; i++) {
+ if (!btf_name_offset_valid(btf, enums[i].name)) {
+ btf_verifier_log(env, "\tInvalid name_offset:%u",
+ enums[i].name);
+ return -EINVAL;
+ }
+
+ btf_verifier_log(env, "\t%s val=%d\n",
+ btf_name_by_offset(btf, enums[i].name),
+ enums[i].val);
+ }
+
+ return meta_needed;
+}
+
+static void btf_enum_log(struct btf_verifier_env *env,
+ const struct btf_type *t)
+{
+ btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
+}
+
+static struct btf_kind_operations enum_ops = {
+ .check_meta = btf_enum_check_meta,
+ .log_details = btf_enum_log,
+};
+
+static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = {
+ [BTF_KIND_INT] = &int_ops,
+ [BTF_KIND_FLOAT] = &df_ops,
+ [BTF_KIND_PTR] = &ptr_ops,
+ [BTF_KIND_ARRAY] = &array_ops,
+ [BTF_KIND_FUNC] = &df_ops,
+ [BTF_KIND_STRUCT] = &struct_ops,
+ [BTF_KIND_UNION] = &struct_ops,
+ [BTF_KIND_ENUM] = &enum_ops,
+ [BTF_KIND_FWD] = &fwd_ops,
+ [BTF_KIND_TYPEDEF] = &modifier_ops,
+ [BTF_KIND_VOLATILE] = &modifier_ops,
+ [BTF_KIND_CONST] = &modifier_ops,
+ [BTF_KIND_RESTRICT] = &modifier_ops,
+};
+
+static s32 btf_check_meta(struct btf_verifier_env *env,
+ const struct btf_type *t,
+ u32 meta_left)
+{
+ u32 saved_meta_left = meta_left;
+ s32 var_meta_size;
+
+ if (meta_left < sizeof(*t)) {
+ btf_verifier_log(env, "[%u] meta_left:%u meta_needed:%zu",
+ env->log_type_id, meta_left, sizeof(*t));
+ return -EINVAL;
+ }
+ meta_left -= sizeof(*t);
+
+ if (BTF_INFO_KIND(t->info) > BTF_KIND_MAX ||
+ BTF_INFO_KIND(t->info) == BTF_KIND_UNKN) {
+ btf_verifier_log(env, "[%u] Invalid kind:%u",
+ env->log_type_id, BTF_INFO_KIND(t->info));
+ return -EINVAL;
+ }
+
+ if (!btf_name_offset_valid(env->btf, t->name)) {
+ btf_verifier_log(env, "[%u] Invalid name_offset:%u",
+ env->log_type_id, t->name);
+ return -EINVAL;
+ }
+
+ var_meta_size = btf_type_ops(t)->check_meta(env, t, meta_left);
+ if (var_meta_size < 0)
+ return var_meta_size;
+
+ meta_left -= var_meta_size;
+
+ return saved_meta_left - meta_left;
+}
+
+static int btf_check_all_metas(struct btf_verifier_env *env)
+{
+ struct btf *btf = env->btf;
+ struct btf_header *hdr;
+ void *cur, *end;
+
+ hdr = btf->hdr;
+ cur = btf->nohdr_data + hdr->type_off;
+ end = btf->nohdr_data + hdr->str_off;
+
+ env->log_type_id = 1;
+ while (cur < end) {
+ struct btf_type *t = cur;
+ s32 meta_size;
+
+ meta_size = btf_check_meta(env, t, end - cur);
+ if (meta_size < 0)
+ return meta_size;
+
+ btf_add_type(env, t);
+ cur += meta_size;
+ env->log_type_id++;
+ }
+
+ return 0;
+}
+
+static int btf_parse_type_sec(struct btf_verifier_env *env)
+{
+ return btf_check_all_metas(env);
+}
+
+static int btf_parse_str_sec(struct btf_verifier_env *env)
+{
+ const struct btf_header *hdr;
+ struct btf *btf = env->btf;
+ const char *start, *end;
+
+ hdr = btf->hdr;
+ start = btf->nohdr_data + hdr->str_off;
+ end = start + hdr->str_len;
+
+ if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET ||
+ start[0] || end[-1]) {
+ btf_verifier_log(env, "Invalid string section");
+ return -EINVAL;
+ }
+
+ btf->strings = start;
+
+ return 0;
+}
+
+static int btf_parse_hdr(struct btf_verifier_env *env)
+{
+ const struct btf_header *hdr;
+ struct btf *btf = env->btf;
+ u32 meta_left;
+
+ if (btf->data_size < sizeof(*hdr)) {
+ btf_verifier_log(env, "btf_header not found");
+ return -EINVAL;
+ }
+
+ btf_verifier_log_hdr(env);
+
+ hdr = btf->hdr;
+ if (hdr->magic != BTF_MAGIC) {
+ btf_verifier_log(env, "Invalid magic");
+ return -EINVAL;
+ }
+
+ if (hdr->version != BTF_VERSION) {
+ btf_verifier_log(env, "Unsupported version");
+ return -ENOTSUPP;
+ }
+
+ if (hdr->flags) {
+ btf_verifier_log(env, "Unsupported flags");
+ return -ENOTSUPP;
+ }
+
+ meta_left = btf->data_size - sizeof(*hdr);
+ if (!meta_left) {
+ btf_verifier_log(env, "No data");
+ return -EINVAL;
+ }
+
+ if (meta_left < hdr->type_off || hdr->str_off <= hdr->type_off ||
+ /* Type section must align to 4 bytes */
+ hdr->type_off & (sizeof(u32) - 1)) {
+ btf_verifier_log(env, "Invalid type_off");
+ return -EINVAL;
+ }
+
+ if (meta_left < hdr->str_off ||
+ meta_left - hdr->str_off < hdr->str_len) {
+ btf_verifier_log(env, "Invalid str_off or str_len");
+ return -EINVAL;
+ }
+
+ btf->nohdr_data = btf->hdr + 1;
+
+ return 0;
+}
+
+static struct btf *btf_parse(void __user *btf_data, u32 btf_data_size,
+ u32 log_level, char __user *log_ubuf, u32 log_size)
+{
+ struct btf_verifier_env *env = NULL;
+ struct bpf_verifier_log *log;
+ struct btf *btf = NULL;
+ u8 *data;
+ int err;
+
+ if (btf_data_size > BTF_MAX_SIZE)
+ return ERR_PTR(-E2BIG);
+
+ env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
+ if (!env)
+ return ERR_PTR(-ENOMEM);
+
+ log = &env->log;
+ if (log_level || log_ubuf || log_size) {
+ /* user requested verbose verifier output
+ * and supplied buffer to store the verification trace
+ */
+ log->level = log_level;
+ log->ubuf = log_ubuf;
+ log->len_total = log_size;
+
+ /* log attributes have to be sane */
+ if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 ||
+ !log->level || !log->ubuf) {
+ err = -EINVAL;
+ goto errout;
+ }
+ }
+
+ btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
+ if (!btf) {
+ err = -ENOMEM;
+ goto errout;
+ }
+
+ data = kvmalloc(btf_data_size, GFP_KERNEL | __GFP_NOWARN);
+ if (!data) {
+ err = -ENOMEM;
+ goto errout;
+ }
+
+ btf->data = data;
+ btf->data_size = btf_data_size;
+
+ if (copy_from_user(data, btf_data, btf_data_size)) {
+ err = -EFAULT;
+ goto errout;
+ }
+
+ env->btf = btf;
+
+ err = btf_parse_hdr(env);
+ if (err)
+ goto errout;
+
+ err = btf_parse_str_sec(env);
+ if (err)
+ goto errout;
+
+ err = btf_parse_type_sec(env);
+ if (err)
+ goto errout;
+
+ if (!err && log->level && bpf_verifier_log_full(log)) {
+ err = -ENOSPC;
+ goto errout;
+ }
+
+ if (!err) {
+ btf_verifier_env_free(env);
+ return btf;
+ }
+
+errout:
+ btf_verifier_env_free(env);
+ if (btf)
+ btf_free(btf);
+ return ERR_PTR(err);
+}
--
2.9.5
