diff options
| -rw-r--r-- | include/linux/btf.h | 36 | ||||
| -rw-r--r-- | kernel/bpf/btf.c | 1007 |
2 files changed, 941 insertions, 102 deletions
diff --git a/include/linux/btf.h b/include/linux/btf.h index a9af5e7a7ece..d0f5d3c9ec3d 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -13,6 +13,7 @@ struct btf; struct btf_member; struct btf_type; union bpf_attr; +struct btf_show; extern const struct file_operations btf_fops; @@ -46,8 +47,43 @@ int btf_get_info_by_fd(const struct btf *btf, const struct btf_type *btf_type_id_size(const struct btf *btf, u32 *type_id, u32 *ret_size); + +/* + * Options to control show behaviour. + * - BTF_SHOW_COMPACT: no formatting around type information + * - BTF_SHOW_NONAME: no struct/union member names/types + * - BTF_SHOW_PTR_RAW: show raw (unobfuscated) pointer values; + * equivalent to %px. + * - BTF_SHOW_ZERO: show zero-valued struct/union members; they + * are not displayed by default + * - BTF_SHOW_UNSAFE: skip use of bpf_probe_read() to safely read + * data before displaying it. + */ +#define BTF_SHOW_COMPACT (1ULL << 0) +#define BTF_SHOW_NONAME (1ULL << 1) +#define BTF_SHOW_PTR_RAW (1ULL << 2) +#define BTF_SHOW_ZERO (1ULL << 3) +#define BTF_SHOW_UNSAFE (1ULL << 4) + void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj, struct seq_file *m); + +/* + * Copy len bytes of string representation of obj of BTF type_id into buf. + * + * @btf: struct btf object + * @type_id: type id of type obj points to + * @obj: pointer to typed data + * @buf: buffer to write to + * @len: maximum length to write to buf + * @flags: show options (see above) + * + * Return: length that would have been/was copied as per snprintf, or + * negative error. + */ +int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj, + char *buf, int len, u64 flags); + int btf_get_fd_by_id(u32 id); u32 btf_id(const struct btf *btf); bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s, diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 868c03a24d0a..dcdd7109aa29 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -284,6 +284,91 @@ static const char *btf_type_str(const struct btf_type *t) return btf_kind_str[BTF_INFO_KIND(t->info)]; } +/* Chunk size we use in safe copy of data to be shown. */ +#define BTF_SHOW_OBJ_SAFE_SIZE 32 + +/* + * This is the maximum size of a base type value (equivalent to a + * 128-bit int); if we are at the end of our safe buffer and have + * less than 16 bytes space we can't be assured of being able + * to copy the next type safely, so in such cases we will initiate + * a new copy. + */ +#define BTF_SHOW_OBJ_BASE_TYPE_SIZE 16 + +/* Type name size */ +#define BTF_SHOW_NAME_SIZE 80 + +/* + * Common data to all BTF show operations. Private show functions can add + * their own data to a structure containing a struct btf_show and consult it + * in the show callback. See btf_type_show() below. + * + * One challenge with showing nested data is we want to skip 0-valued + * data, but in order to figure out whether a nested object is all zeros + * we need to walk through it. As a result, we need to make two passes + * when handling structs, unions and arrays; the first path simply looks + * for nonzero data, while the second actually does the display. The first + * pass is signalled by show->state.depth_check being set, and if we + * encounter a non-zero value we set show->state.depth_to_show to + * the depth at which we encountered it. When we have completed the + * first pass, we will know if anything needs to be displayed if + * depth_to_show > depth. See btf_[struct,array]_show() for the + * implementation of this. + * + * Another problem is we want to ensure the data for display is safe to + * access. To support this, the anonymous "struct {} obj" tracks the data + * object and our safe copy of it. We copy portions of the data needed + * to the object "copy" buffer, but because its size is limited to + * BTF_SHOW_OBJ_COPY_LEN bytes, multiple copies may be required as we + * traverse larger objects for display. + * + * The various data type show functions all start with a call to + * btf_show_start_type() which returns a pointer to the safe copy + * of the data needed (or if BTF_SHOW_UNSAFE is specified, to the + * raw data itself). btf_show_obj_safe() is responsible for + * using copy_from_kernel_nofault() to update the safe data if necessary + * as we traverse the object's data. skbuff-like semantics are + * used: + * + * - obj.head points to the start of the toplevel object for display + * - obj.size is the size of the toplevel object + * - obj.data points to the current point in the original data at + * which our safe data starts. obj.data will advance as we copy + * portions of the data. + * + * In most cases a single copy will suffice, but larger data structures + * such as "struct task_struct" will require many copies. The logic in + * btf_show_obj_safe() handles the logic that determines if a new + * copy_from_kernel_nofault() is needed. + */ +struct btf_show { + u64 flags; + void *target; /* target of show operation (seq file, buffer) */ + void (*showfn)(struct btf_show *show, const char *fmt, va_list args); + const struct btf *btf; + /* below are used during iteration */ + struct { + u8 depth; + u8 depth_to_show; + u8 depth_check; + u8 array_member:1, + array_terminated:1; + u16 array_encoding; + u32 type_id; + int status; /* non-zero for error */ + const struct btf_type *type; + const struct btf_member *member; + char name[BTF_SHOW_NAME_SIZE]; /* space for member name/type */ + } state; + struct { + u32 size; + void *head; + void *data; + u8 safe[BTF_SHOW_OBJ_SAFE_SIZE]; + } obj; +}; + struct btf_kind_operations { s32 (*check_meta)(struct btf_verifier_env *env, const struct btf_type *t, @@ -300,9 +385,9 @@ struct btf_kind_operations { const struct btf_type *member_type); void (*log_details)(struct btf_verifier_env *env, const struct btf_type *t); - void (*seq_show)(const struct btf *btf, const struct btf_type *t, + void (*show)(const struct btf *btf, const struct btf_type *t, u32 type_id, void *data, u8 bits_offsets, - struct seq_file *m); + struct btf_show *show); }; static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS]; @@ -679,6 +764,488 @@ bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s, return true; } +/* Similar to btf_type_skip_modifiers() but does not skip typedefs. */ +static const struct btf_type *btf_type_skip_qualifiers(const struct btf *btf, + u32 id) +{ + const struct btf_type *t = btf_type_by_id(btf, id); + + while (btf_type_is_modifier(t) && + BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF) { + id = t->type; + t = btf_type_by_id(btf, t->type); + } + + return t; +} + +#define BTF_SHOW_MAX_ITER 10 + +#define BTF_KIND_BIT(kind) (1ULL << kind) + +/* + * Populate show->state.name with type name information. + * Format of type name is + * + * [.member_name = ] (type_name) + */ +static const char *btf_show_name(struct btf_show *show) +{ + /* BTF_MAX_ITER array suffixes "[]" */ + const char *array_suffixes = "[][][][][][][][][][]"; + const char *array_suffix = &array_suffixes[strlen(array_suffixes)]; + /* BTF_MAX_ITER pointer suffixes "*" */ + const char *ptr_suffixes = "**********"; + const char *ptr_suffix = &ptr_suffixes[strlen(ptr_suffixes)]; + const char *name = NULL, *prefix = "", *parens = ""; + const struct btf_member *m = show->state.member; + const struct btf_type *t = show->state.type; + const struct btf_array *array; + u32 id = show->state.type_id; + const char *member = NULL; + bool show_member = false; + u64 kinds = 0; + int i; + + show->state.name[0] = '\0'; + + /* + * Don't show type name if we're showing an array member; + * in that case we show the array type so don't need to repeat + * ourselves for each member. + */ + if (show->state.array_member) + return ""; + + /* Retrieve member name, if any. */ + if (m) { + member = btf_name_by_offset(show->btf, m->name_off); + show_member = strlen(member) > 0; + id = m->type; + } + + /* + * Start with type_id, as we have resolved the struct btf_type * + * via btf_modifier_show() past the parent typedef to the child + * struct, int etc it is defined as. In such cases, the type_id + * still represents the starting type while the struct btf_type * + * in our show->state points at the resolved type of the typedef. + */ + t = btf_type_by_id(show->btf, id); + if (!t) + return ""; + + /* + * The goal here is to build up the right number of pointer and + * array suffixes while ensuring the type name for a typedef + * is represented. Along the way we accumulate a list of + * BTF kinds we have encountered, since these will inform later + * display; for example, pointer types will not require an + * opening "{" for struct, we will just display the pointer value. + * + * We also want to accumulate the right number of pointer or array + * indices in the format string while iterating until we get to + * the typedef/pointee/array member target type. + * + * We start by pointing at the end of pointer and array suffix + * strings; as we accumulate pointers and arrays we move the pointer + * or array string backwards so it will show the expected number of + * '*' or '[]' for the type. BTF_SHOW_MAX_ITER of nesting of pointers + * and/or arrays and typedefs are supported as a precaution. + * + * We also want to get typedef name while proceeding to resolve + * type it points to so that we can add parentheses if it is a + * "typedef struct" etc. + */ + for (i = 0; i < BTF_SHOW_MAX_ITER; i++) { + + switch (BTF_INFO_KIND(t->info)) { + case BTF_KIND_TYPEDEF: + if (!name) + name = btf_name_by_offset(show->btf, + t->name_off); + kinds |= BTF_KIND_BIT(BTF_KIND_TYPEDEF); + id = t->type; + break; + case BTF_KIND_ARRAY: + kinds |= BTF_KIND_BIT(BTF_KIND_ARRAY); + parens = "["; + if (!t) + return ""; + array = btf_type_array(t); + if (array_suffix > array_suffixes) + array_suffix -= 2; + id = array->type; + break; + case BTF_KIND_PTR: + kinds |= BTF_KIND_BIT(BTF_KIND_PTR); + if (ptr_suffix > ptr_suffixes) + ptr_suffix -= 1; + id = t->type; + break; + default: + id = 0; + break; + } + if (!id) + break; + t = btf_type_skip_qualifiers(show->btf, id); + } + /* We may not be able to represent this type; bail to be safe */ + if (i == BTF_SHOW_MAX_ITER) + return ""; + + if (!name) + name = btf_name_by_offset(show->btf, t->name_off); + + switch (BTF_INFO_KIND(t->info)) { + case BTF_KIND_STRUCT: + case BTF_KIND_UNION: + prefix = BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT ? + "struct" : "union"; + /* if it's an array of struct/union, parens is already set */ + if (!(kinds & (BTF_KIND_BIT(BTF_KIND_ARRAY)))) + parens = "{"; + break; + case BTF_KIND_ENUM: + prefix = "enum"; + break; + default: + break; + } + + /* pointer does not require parens */ + if (kinds & BTF_KIND_BIT(BTF_KIND_PTR)) + parens = ""; + /* typedef does not require struct/union/enum prefix */ + if (kinds & BTF_KIND_BIT(BTF_KIND_TYPEDEF)) + prefix = ""; + + if (!name) + name = ""; + + /* Even if we don't want type name info, we want parentheses etc */ + if (show->flags & BTF_SHOW_NONAME) + snprintf(show->state.name, sizeof(show->state.name), "%s", + parens); + else + snprintf(show->state.name, sizeof(show->state.name), + "%s%s%s(%s%s%s%s%s%s)%s", + /* first 3 strings comprise ".member = " */ + show_member ? "." : "", + show_member ? member : "", + show_member ? " = " : "", + /* ...next is our prefix (struct, enum, etc) */ + prefix, + strlen(prefix) > 0 && strlen(name) > 0 ? " " : "", + /* ...this is the type name itself */ + name, + /* ...suffixed by the appropriate '*', '[]' suffixes */ + strlen(ptr_suffix) > 0 ? " " : "", ptr_suffix, + array_suffix, parens); + + return show->state.name; +} + +static const char *__btf_show_indent(struct btf_show *show) +{ + const char *indents = " "; + const char *indent = &indents[strlen(indents)]; + + if ((indent - show->state.depth) >= indents) + return indent - show->state.depth; + return indents; +} + +static const char *btf_show_indent(struct btf_show *show) +{ + return show->flags & BTF_SHOW_COMPACT ? "" : __btf_show_indent(show); +} + +static const char *btf_show_newline(struct btf_show *show) +{ + return show->flags & BTF_SHOW_COMPACT ? "" : "\n"; +} + +static const char *btf_show_delim(struct btf_show *show) +{ + if (show->state.depth == 0) + return ""; + + if ((show->flags & BTF_SHOW_COMPACT) && show->state.type && + BTF_INFO_KIND(show->state.type->info) == BTF_KIND_UNION) + return "|"; + + return ","; +} + +__printf(2, 3) static void btf_show(struct btf_show *show, const char *fmt, ...) +{ + va_list args; + + if (!show->state.depth_check) { + va_start(args, fmt); + show->showfn(show, fmt, args); + va_end(args); + } +} + +/* Macros are used here as btf_show_type_value[s]() prepends and appends + * format specifiers to the format specifier passed in; these do the work of + * adding indentation, delimiters etc while the caller simply has to specify + * the type value(s) in the format specifier + value(s). + */ +#define btf_show_type_value(show, fmt, value) \ + do { \ + if ((value) != 0 || (show->flags & BTF_SHOW_ZERO) || \ + show->state.depth == 0) { \ + btf_show(show, "%s%s" fmt "%s%s", \ + btf_show_indent(show), \ + btf_show_name(show), \ + value, btf_show_delim(show), \ + btf_show_newline(show)); \ + if (show->state.depth > show->state.depth_to_show) \ + show->state.depth_to_show = show->state.depth; \ + } \ + } while (0) + +#define btf_show_type_values(show, fmt, ...) \ + do { \ + btf_show(show, "%s%s" fmt "%s%s", btf_show_indent(show), \ + btf_show_name(show), \ + __VA_ARGS__, btf_show_delim(show), \ + btf_show_newline(show)); \ + if (show->state.depth > show->state.depth_to_show) \ + show->state.depth_to_show = show->state.depth; \ + } while (0) + +/* How much is left to copy to safe buffer after @data? */ +static int btf_show_obj_size_left(struct btf_show *show, void *data) +{ + return show->obj.head + show->obj.size - data; +} + +/* Is object pointed to by @data of @size already copied to our safe buffer? */ +static bool btf_show_obj_is_safe(struct btf_show *show, void *data, int size) +{ + return data >= show->obj.data && + (data + size) < (show->obj.data + BTF_SHOW_OBJ_SAFE_SIZE); +} + +/* + * If object pointed to by @data of @size falls within our safe buffer, return + * the equivalent pointer to the same safe data. Assumes + * copy_from_kernel_nofault() has already happened and our safe buffer is + * populated. + */ +static void *__btf_show_obj_safe(struct btf_show *show, void *data, int size) +{ + if (btf_show_obj_is_safe(show, data, size)) + return show->obj.safe + (data - show->obj.data); + return NULL; +} + +/* + * Return a safe-to-access version of data pointed to by @data. + * We do this by copying the relevant amount of information + * to the struct btf_show obj.safe buffer using copy_from_kernel_nofault(). + * + * If BTF_SHOW_UNSAFE is specified, just return data as-is; no + * safe copy is needed. + * + * Otherwise we need to determine if we have the required amount + * of data (determined by the @data pointer and the size of the + * largest base type we can encounter (represented by + * BTF_SHOW_OBJ_BASE_TYPE_SIZE). Having that much data ensures + * that we will be able to print some of the current object, + * and if more is needed a copy will be triggered. + * Some objects such as structs will not fit into the buffer; + * in such cases additional copies when we iterate over their + * members may be needed. + * + * btf_show_obj_safe() is used to return a safe buffer for + * btf_show_start_type(); this ensures that as we recurse into + * nested types we always have safe data for the given type. + * This approach is somewhat wasteful; it's possible for example + * that when iterating over a large union we'll end up copying the + * same data repeatedly, but the goal is safety not performance. + * We use stack data as opposed to per-CPU buffers because the + * iteration over a type can take some time, and preemption handling + * would greatly complicate use of the safe buffer. + */ +static void *btf_show_obj_safe(struct btf_show *show, + const struct btf_type *t, + void *data) +{ + const struct btf_type *rt; + int size_left, size; + void *safe = NULL; + + if (show->flags & BTF_SHOW_UNSAFE) + return data; + + rt = btf_resolve_size(show->btf, t, &size); + if (IS_ERR(rt)) { + show->state.status = PTR_ERR(rt); + return NULL; + } + + /* + * Is this toplevel object? If so, set total object size and + * initialize pointers. Otherwise check if we still fall within + * our safe object data. + */ + if (show->state.depth == 0) { + show->obj.size = size; + show->obj.head = data; + } else { + /* + * If the size of the current object is > our remaining + * safe buffer we _may_ need to do a new copy. However + * consider the case of a nested struct; it's size pushes + * us over the safe buffer limit, but showing any individual + * struct members does not. In such cases, we don't need + * to initiate a fresh copy yet; however we definitely need + * at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes left + * in our buffer, regardless of the current object size. + * The logic here is that as we resolve types we will + * hit a base type at some point, and we need to be sure + * the next chunk of data is safely available to display + * that type info safely. We cannot rely on the size of + * the current object here because it may be much larger + * than our current buffer (e.g. task_struct is 8k). + * All we want to do here is ensure that we can print the + * next basic type, which we can if either + * - the current type size is within the safe buffer; or + * - at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes are left in + * the safe buffer. + */ + safe = __btf_show_obj_safe(show, data, + min(size, + BTF_SHOW_OBJ_BASE_TYPE_SIZE)); + } + + /* + * We need a new copy to our safe object, either because we haven't + * yet copied and are intializing safe data, or because the data + * we want falls outside the boundaries of the safe object. + */ + if (!safe) { + size_left = btf_show_obj_size_left(show, data); + if (size_left > BTF_SHOW_OBJ_SAFE_SIZE) + size_left = BTF_SHOW_OBJ_SAFE_SIZE; + show->state.status = copy_from_kernel_nofault(show->obj.safe, + data, size_left); + if (!show->state.status) { + show->obj.data = data; + safe = show->obj.safe; + } + } + + return safe; +} + +/* + * Set the type we are starting to show and return a safe data pointer + * to be used for showing the associated data. + */ +static void *btf_show_start_type(struct btf_show *show, + const struct btf_type *t, + u32 type_id, void *data) +{ + show->state.type = t; + show->state.type_id = type_id; + show->state.name[0] = '\0'; + + return btf_show_obj_safe(show, t, data); +} + +static void btf_show_end_type(struct btf_show *show) +{ + show->state.type = NULL; + show->state.type_id = 0; + show->state.name[0] = '\0'; +} + +static void *btf_show_start_aggr_type(struct btf_show *show, + const struct btf_type *t, + u32 type_id, void *data) +{ + void *safe_data = btf_show_start_type(show, t, type_id, data); + + if (!safe_data) + return safe_data; + + btf_show(show, "%s%s%s", btf_show_indent(show), + btf_show_name(show), + btf_show_newline(show)); + show->state.depth++; + return safe_data; +} + +static void btf_show_end_aggr_type(struct btf_show *show, + const char *suffix) +{ + show->state.depth--; + btf_show(show, "%s%s%s%s", btf_show_indent(show), suffix, + btf_show_delim(show), btf_show_newline(show)); + btf_show_end_type(show); +} + +static void btf_show_start_member(struct btf_show *show, + const struct btf_member *m) +{ + show->state.member = m; +} + +static void btf_show_start_array_member(struct btf_show *show) +{ + show->state.array_member = 1; + btf_show_start_member(show, NULL); +} + +static void btf_show_end_member(struct btf_show *show) +{ + show->state.member = NULL; +} + +static void btf_show_end_array_member(struct btf_show *show) +{ + show->state.array_member = 0; + btf_show_end_member(show); +} + +static void *btf_show_start_array_type(struct btf_show *show, + const struct btf_type *t, + u32 type_id, + u16 array_encoding, + void *data) +{ + show->state.array_encoding = array_encoding; + show->state.array_terminated = 0; + return btf_show_start_aggr_type(show, t, type_id, data); +} + +static void btf_show_end_array_type(struct btf_show *show) +{ + show->state.array_encoding = 0; + show->state.array_terminated = 0; + btf_show_end_aggr_type(show, "]"); +} + +static void *btf_show_start_struct_type(struct btf_show *show, + const struct btf_type *t, + u32 type_id, + void *data) +{ + return btf_show_start_aggr_type(show, t, type_id, data); +} + +static void btf_show_end_struct_type(struct btf_show *show) +{ + btf_show_end_aggr_type(show, "}"); +} + __printf(2, 3) static void __btf_verifier_log(struct bpf_verifier_log *log, const char *fmt, ...) { @@ -1268,11 +1835,11 @@ static int btf_df_resolve(struct btf_verifier_env *env, return -EINVAL; } -static void btf_df_seq_show(const struct btf *btf, const struct btf_type *t, - u32 type_id, void *data, u8 bits_offsets, - struct seq_file *m) +static void btf_df_show(const struct btf *btf, const struct btf_type *t, + u32 type_id, void *data, u8 bits_offsets, + struct btf_show *show) { - seq_printf(m, "<unsupported kind:%u>", BTF_INFO_KIND(t->info)); + btf_show(show, "<unsupported kind:%u>", BTF_INFO_KIND(t->info)); } static int btf_int_check_member(struct btf_verifier_env *env, @@ -1445,7 +2012,7 @@ static void btf_int_log(struct btf_verifier_env *env, btf_int_encoding_str(BTF_INT_ENCODING(int_data))); } -static void btf_int128_print(struct seq_file *m, void *data) +static void btf_int128_print(struct btf_show *show, void *data) { /* data points to a __int128 number. * Suppose @@ -1464,9 +2031,10 @@ static void btf_int128_print(struct seq_file *m, void *data) lower_num = *(u64 *)data; #endif if (upper_num == 0) - seq_printf(m, "0x%llx", lower_num); + btf_show_type_value(show, "0x%llx", lower_num); else - seq_printf(m, "0x%llx%016llx", upper_num, lower_num); + btf_show_type_values(show, "0x%llx%016llx", upper_num, + lower_num); } static void btf_int128_shift(u64 *print_num, u16 left_shift_bits, @@ -1510,8 +2078,8 @@ static void btf_int128_shift(u64 *print_num, u16 left_shift_bits, #endif } -static void btf_bitfield_seq_show(void *data, u8 bits_offset, - u8 nr_bits, struct seq_file *m) +static void btf_bitfield_show(void *data, u8 bits_offset, + u8 nr_bits, struct btf_show *show) { u16 left_shift_bits, right_shift_bits; u8 nr_copy_bytes; @@ -1531,14 +2099,14 @@ static void btf_bitfield_seq_show(void *data, u8 bits_offset, right_shift_bits = BITS_PER_U128 - nr_bits; btf_int128_shift(print_num, left_shift_bits, right_shift_bits); - btf_int128_print(m, print_num); + btf_int128_print(show, print_num); } -static void btf_int_bits_seq_show(const struct btf *btf, - const struct btf_type *t, - void *data, u8 bits_offset, - struct seq_file *m) +static void btf_int_bits_show(const struct btf *btf, + const struct btf_type *t, + void *data, u8 bits_offset, + struct btf_show *show) { u32 int_data = btf_type_int(t); u8 nr_bits = BTF_INT_BITS(int_data); @@ -1551,55 +2119,77 @@ static void btf_int_bits_seq_show(const struct btf *btf, total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data); data += BITS_ROUNDDOWN_BYTES(total_bits_offset); bits_offset = BITS_PER_BYTE_MASKED(total_bits_offset); - btf_bitfield_seq_show(data, bits_offset, nr_bits, m); + btf_bitfield_show(data, bits_offset, nr_bits, show); } -static void btf_int_seq_show(const struct btf *btf, const struct btf_type *t, - u32 type_id, void *data, u8 bits_offset, - struct seq_file *m) +static void btf_int_show(const struct btf *btf, const struct btf_type *t, + u32 type_id, void *data, u8 bits_offset, + struct btf_show *show) { u32 int_data = btf_type_int(t); u8 encoding = BTF_INT_ENCODING(int_data); bool sign = encoding & BTF_INT_SIGNED; u8 nr_bits = BTF_INT_BITS(int_data); + void *safe_data; + + safe_data = btf_show_start_type(show, t, type_id, data); + if (!safe_data) + return; if (bits_offset || BTF_INT_OFFSET(int_data) || BITS_PER_BYTE_MASKED(nr_bits)) { - btf_int_bits_seq_show(btf, t, data, bits_offset, m); - return; + btf_int_bits_show(btf, t, safe_data, bits_offset, show); + goto out; } switch (nr_bits) { case 128: - btf_int128_print(m, data); + btf_int128_print(show, safe_data); break; case 64: if (sign) - seq_printf(m, "%lld", *(s64 *)data); + btf_show_type_value(show, "%lld", *(s64 *)safe_data); else - seq_printf(m, "%llu", *(u64 *)data); + btf_show_type_value(show, "%llu", *(u64 *)safe_data); break; case 32: if (sign) - seq_printf(m, "%d", *(s32 *)data); + btf_show_type_value(show, "%d", *(s32 *)safe_data); else - seq_printf(m, "%u", *(u32 *)data); + btf_show_type_value(show, "%u", *(u32 *)safe_data); break; case 16: if (sign) - seq_printf(m, "%d", *(s16 *)data); + btf_show_type_value(show, "%d", *(s16 *)safe_data); else - seq_printf(m, "%u", *(u16 *)data); + btf_show_type_value(show, "%u", *(u16 *)safe_data); break; case 8: + if (show->state.array_encoding == BTF_INT_CHAR) { + /* check for null terminator */ + if (show->state.array_terminated) + break; + if (*(char *)data == '\0') { + show->state.array_terminated = 1; + break; + } + if (isprint(*(char *)data)) { + btf_show_type_value(show, "'%c'", + *(char *)safe_data); + break; + } + } if (sign) - seq_printf(m, "%d", *(s8 *)data); + btf_show_type_value(show, "%d", *(s8 *)safe_data); else - seq_printf(m, "%u", *(u8 *)data); + btf_show_type_value(show, "%u", *(u8 *)safe_data); break; default: - btf_int_bits_seq_show(btf, t, data, bits_offset, m); + btf_int_bits_show(btf, t, safe_data, bits_offset, show); + break; } +out: + btf_show_end_type(show); } static const struct btf_kind_operations int_ops = { @@ -1608,7 +2198,7 @@ static const struct btf_kind_operations int_ops = { .check_member = btf_int_check_member, .check_kflag_member = btf_int_check_kflag_member, .log_details = btf_int_log, - .seq_show = btf_int_seq_show, + .show = btf_int_show, }; static int btf_modifier_check_member(struct btf_verifier_env *env, @@ -1872,34 +2462,44 @@ static int btf_ptr_resolve(struct btf_verifier_env *env, return 0; } -static void btf_modifier_seq_show(const struct btf *btf, - const struct btf_type *t, - u32 type_id, void *data, - u8 bits_offset, struct seq_file *m) +static void btf_modifier_show(const struct btf *btf, + const struct btf_type *t, + u32 type_id, void *data, + u8 bits_offset, struct btf_show *show) { if (btf->resolved_ids) t = btf_type_id_resolve(btf, &type_id); else t = btf_type_skip_modifiers(btf, type_id, NULL); - btf_type_ops(t)->seq_show(btf, t, type_id, data, bits_offset, m); + btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show); } -static void btf_var_seq_show(const struct btf *btf, const struct btf_type *t, - u32 type_id, void *data, u8 bits_offset, - struct seq_file *m) +static void btf_var_show(const struct btf *btf, const struct btf_type *t, + u32 type_id, void *data, u8 bits_offset, + struct btf_show *show) { t = btf_type_id_resolve(btf, &type_id); - btf_type_ops(t)->seq_show(btf, t, type_id, data, bits_offset, m); + btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show); } -static void btf_ptr_seq_show(const struct btf *btf, const struct btf_type *t, - u32 type_id, void *data, u8 bits_offset, - struct seq_file *m) +static void btf_ptr_show(const struct btf *btf, const struct btf_type *t, + u32 type_id, void *data, u8 bits_offset, + struct btf_show *show) { - /* It is a hashed value */ - seq_printf(m, "%p", *(void **)data); + void *safe_data; + + safe_data = btf_show_start_type(show, t, type_id, data); + if (!safe_data) + return; + + /* It is a hashed value unless BTF_SHOW_PTR_RAW is specified */ + if (show->flags & BTF_SHOW_PTR_RAW) + btf_show_type_value(show, "0x%px", *(void **)safe_data); + else + btf_show_type_value(show, "0x%p", *(void **)safe_data); + btf_show_end_type(show); } static void btf_ref_type_log(struct btf_verifier_env *env, @@ -1914,7 +2514,7 @@ static struct btf_kind_operations modifier_ops = { .check_member = btf_modifier_check_member, .check_kflag_member = btf_modifier_check_kflag_member, .log_details = btf_ref_type_log, - .seq_show = btf_modifier_seq_show, + .show = btf_modifier_show, }; static struct btf_kind_operations ptr_ops = { @@ -1923,7 +2523,7 @@ static struct btf_kind_operations ptr_ops = { .check_member = btf_ptr_check_member, .check_kflag_member = btf_generic_check_kflag_member, .log_details = btf_ref_type_log, - .seq_show = btf_ptr_seq_show, + .show = btf_ptr_show, }; static s32 btf_fwd_check_meta(struct btf_verifier_env *env, @@ -1964,7 +2564,7 @@ static struct btf_kind_operations fwd_ops = { .check_member = btf_df_check_member, .check_kflag_member = btf_df_check_kflag_member, .log_details = btf_fwd_type_log, - .seq_show = btf_df_seq_show, + .show = btf_df_show, }; static int btf_array_check_member(struct btf_verifier_env *env, @@ -2123,28 +2723,90 @@ static void btf_array_log(struct btf_verifier_env *env, array->type, array->index_type, array->nelems); } -static void btf_array_seq_show(const struct btf *btf, const struct btf_type *t, - u32 type_id, void *data, u8 bits_offset, - struct seq_file *m) +static void __btf_array_show(const struct btf *btf, const struct btf_type *t, + u32 type_id, void *data, u8 bits_offset, + struct btf_show *show) { const struct btf_array *array = btf_type_array(t); const struct btf_kind_operations *elem_ops; const struct btf_type *elem_type; - u32 i, elem_size, elem_type_id; + u32 i, elem_size = 0, elem_type_id; + u16 encoding = 0; elem_type_id = array->type; - elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size); + elem_type = btf_type_skip_modifiers(btf, elem_type_id, NULL); + if (elem_type && btf_type_has_size(elem_type)) + elem_size = elem_type->size; + + if (elem_type && btf_type_is_int(elem_type)) { + u32 int_type = btf_type_int(elem_type); + + encoding = BTF_INT_ENCODING(int_type); + + /* + * BTF_INT_CHAR encoding never seems to be set for + * char arrays, so if size is 1 and element is + * printable as a char, we'll do that. + */ + if (elem_size == 1) + encoding = BTF_INT_CHAR; + } + + if (!btf_show_start_array_type(show, t, type_id, encoding, data)) + return; + + if (!elem_type) + goto out; elem_ops = btf_type_ops(elem_type); - seq_puts(m, "["); + for (i = 0; i < array->nelems; i++) { - if (i) - seq_puts(m, ","); - elem_ops->seq_show(btf, elem_type, elem_type_id, data, - bits_offset, m); + btf_show_start_array_member(show); + + elem_ops->show(btf, elem_type, elem_type_id, data, + bits_offset, show); data += elem_size; + + btf_show_end_array_member(show); + + if (show->state.array_terminated) + break; } - seq_puts(m, "]"); +out: + btf_show_end_array_type(show); +} + +static void btf_array_show(const struct btf *btf, const struct btf_type *t, + u32 type_id, void *data, u8 bits_offset, + struct btf_show *show) +{ + const struct btf_member *m = show->state.member; + + /* + * First check if any members would be shown (are non-zero). + * See comments above "struct btf_show" definition for more + * details on how this works at a high-level. + */ + if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) { + if (!show->state.depth_check) { + show->state.depth_check = show->state.depth + 1; + show->state.depth_to_show = 0; + } + __btf_array_show(btf, t, type_id, data, bits_offset, show); + show->state.member = m; + + if (show->state.depth_check != show->state.depth + 1) + return; + show->state.depth_check = 0; + + if (show->state.depth_to_show <= show->state.depth) + return; + /* + * Reaching here indicates we have recursed and found + * non-zero array member(s). + */ + } + __btf_array_show(btf, t, type_id, data, bits_offset, show); } static struct btf_kind_operations array_ops = { @@ -2153,7 +2815,7 @@ static struct btf_kind_operations array_ops = { .check_member = btf_array_check_member, .check_kflag_member = btf_generic_check_kflag_member, .log_details = btf_array_log, - .seq_show = btf_array_seq_show, + .show = btf_array_show, }; static int btf_struct_check_member(struct btf_verifier_env *env, @@ -2376,15 +3038,18 @@ int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t) return off; } -static void btf_struct_seq_show(const struct btf *btf, const struct btf_type *t, - u32 type_id, void *data, u8 bits_offset, - struct seq_file *m) +static void __btf_struct_show(const struct btf *btf, const struct btf_type *t, + u32 type_id, void *data, u8 bits_offset, + struct btf_show *show) { - const char *seq = BTF_INFO_KIND(t->info) == BTF_KIND_UNION ? "|" : ","; const struct btf_member *member; + void *safe_data; u32 i; - seq_puts(m, "{"); + safe_data = btf_show_start_struct_type(show, t, type_id, data); + if (!safe_data) + return; + for_each_member(i, t, member) { const struct btf_type *member_type = btf_type_by_id(btf, member->type); @@ -2393,23 +3058,65 @@ static void btf_struct_seq_show(const struct btf *btf, const struct btf_type *t, u32 bytes_offset; u8 bits8_offset; - if (i) - seq_puts(m, seq); + btf_show_start_member(show, member); member_offset = btf_member_bit_offset(t, member); bitfield_size = btf_member_bitfield_size(t, member); bytes_offset = BITS_ROUNDDOWN_BYTES(member_offset); bits8_offset = BITS_PER_BYTE_MASKED(member_offset); if (bitfield_size) { - btf_bitfield_seq_show(data + bytes_offset, bits8_offset, - bitfield_size, m); + safe_data = btf_show_start_type(show, member_type, + member->type, + data + bytes_offset); + if (safe_data) + btf_bitfield_show(safe_data, + bits8_offset, + bitfield_size, show); + btf_show_end_type(show); } else { ops = btf_type_ops(member_type); - ops->seq_show(btf, member_type, member->type, - data + bytes_offset, bits8_offset, m); + ops->show(btf, member_type, member->type, + data + bytes_offset, bits8_offset, show); } + + btf_show_end_member(show); } - seq_puts(m, "}"); + + btf_show_end_struct_type(show); +} + +static void btf_struct_show(const struct btf *btf, const struct btf_type *t, + u32 type_id, void *data, u8 bits_offset, + struct btf_show *show) +{ + const struct btf_member *m = show->state.member; + + /* + * First check if any members would be shown (are non-zero). + * See comments above "struct btf_show" definition for more + * details on how this works at a high-level. + */ + if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) { + if (!show->state.depth_check) { + show->state.depth_check = show->state.depth + 1; + show->state.depth_to_show = 0; + } + __btf_struct_show(btf, t, type_id, data, bits_offset, show); + /* Restore saved member data here */ + show->state.member = m; + if (show->state.depth_check != show->state.depth + 1) + return; + show->state.depth_check = 0; + + if (show->state.depth_to_show <= show->state.depth) + return; + /* + * Reaching here indicates we have recursed and found + * non-zero child values. + */ + } + + __btf_struct_show(btf, t, type_id, data, bits_offset, show); } static struct btf_kind_operations struct_ops = { @@ -2418,7 +3125,7 @@ static struct btf_kind_operations struct_ops = { .check_member = btf_struct_check_member, .check_kflag_member = btf_generic_check_kflag_member, .log_details = btf_struct_log, - .seq_show = btf_struct_seq_show, + .show = btf_struct_show, }; static int btf_enum_check_member(struct btf_verifier_env *env, @@ -2549,24 +3256,35 @@ static void btf_enum_log(struct btf_verifier_env *env, btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t)); } -static void btf_enum_seq_show(const struct btf *btf, const struct btf_type *t, - u32 type_id, void *data, u8 bits_offset, - struct seq_file *m) +static void btf_enum_show(const struct btf *btf, const struct btf_type *t, + u32 type_id, void *data, u8 bits_offset, + struct btf_show *show) { const struct btf_enum *enums = btf_type_enum(t); u32 i, nr_enums = btf_type_vlen(t); - int v = *(int *)data; + void *safe_data; + int v; + + safe_data = btf_show_start_type(show, t, type_id, data); + if (!safe_data) + return; + + v = *(int *)safe_data; for (i = 0; i < nr_enums; i++) { - if (v == enums[i].val) { - seq_printf(m, "%s", - __btf_name_by_offset(btf, - enums[i].name_off)); - return; - } + if (v != enums[i].val) + continue; + + btf_show_type_value(show, "%s", + __btf_name_by_offset(btf, + enums[i].name_off)); + + btf_show_end_type(show); + return; } - seq_printf(m, "%d", v); + btf_show_type_value(show, "%d", v); + btf_show_end_type(show); } static struct btf_kind_operations enum_ops = { @@ -2575,7 +3293,7 @@ static struct btf_kind_operations enum_ops = { .check_member = btf_enum_check_member, .check_kflag_member = btf_enum_check_kflag_member, .log_details = btf_enum_log, - .seq_show = btf_enum_seq_show, + .show = btf_enum_show, }; static s32 btf_func_proto_check_meta(struct btf_verifier_env *env, @@ -2662,7 +3380,7 @@ static struct btf_kind_operations func_proto_ops = { .check_member = btf_df_check_member, .check_kflag_member = btf_df_check_kflag_member, .log_details = btf_func_proto_log, - .seq_show = btf_df_seq_show, + .show = btf_df_show, }; static s32 btf_func_check_meta(struct btf_verifier_env *env, @@ -2696,7 +3414,7 @@ static struct btf_kind_operations func_ops = { .check_member = btf_df_check_member, .check_kflag_member = btf_df_check_kflag_member, .log_details = btf_ref_type_log, - .seq_show = btf_df_seq_show, + .show = btf_df_show, }; static s32 btf_var_check_meta(struct btf_verifier_env *env, @@ -2760,7 +3478,7 @@ static const struct btf_kind_operations var_ops = { .check_member = btf_df_check_member, .check_kflag_member = btf_df_check_kflag_member, .log_details = btf_var_log, - .seq_show = btf_var_seq_show, + .show = btf_var_show, }; static s32 btf_datasec_check_meta(struct btf_verifier_env *env, @@ -2886,24 +3604,28 @@ static void btf_datasec_log(struct btf_verifier_env *env, btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t)); } -static void btf_datasec_seq_show(const struct btf *btf, - const struct btf_type *t, u32 type_id, - void *data, u8 bits_offset, - struct seq_file *m) +static void btf_datasec_show(const struct btf *btf, + const struct btf_type *t, u32 type_id, + void *data, u8 bits_offset, + struct btf_show *show) { const struct btf_var_secinfo *vsi; const struct btf_type *var; u32 i; - seq_printf(m, "section (\"%s\") = {", __btf_name_by_offset(btf, t->name_off)); + if (!btf_show_start_type(show, t, type_id, data)) + return; + + btf_show_type_value(show, "section (\"%s\") = {", + __btf_name_by_offset(btf, t->name_off)); for_each_vsi(i, t, vsi) { var = btf_type_by_id(btf, vsi->type); if (i) - seq_puts(m, ","); - btf_type_ops(var)->seq_show(btf, var, vsi->type, - data + vsi->offset, bits_offset, m); + btf_show(show, ","); + btf_type_ops(var)->show(btf, var, vsi->type, + data + vsi->offset, bits_offset, show); } - seq_puts(m, "}"); + btf_show_end_type(show); } static const struct btf_kind_operations datasec_ops = { @@ -2912,7 +3634,7 @@ static const struct btf_kind_operations datasec_ops = { .check_member = btf_df_check_member, .check_kflag_member = btf_df_check_kflag_member, .log_details = btf_datasec_log, - .seq_show = btf_datasec_seq_show, + .show = btf_datasec_show, }; static int btf_func_proto_check(struct btf_verifier_env *env, @@ -4606,12 +5328,93 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, return 0; } +static void btf_type_show(const struct btf *btf, u32 type_id, void *obj, + struct btf_show *show) +{ + const struct btf_type *t = btf_type_by_id(btf, type_id); + + show->btf = btf; + memset(&show->state, 0, sizeof(show->state)); + memset(&show->obj, 0, sizeof(show->obj)); + + btf_type_ops(t)->show(btf, t, type_id, obj, 0, show); +} + +static void btf_seq_show(struct btf_show *show, const char *fmt, + va_list args) +{ + seq_vprintf((struct seq_file *)show->target, fmt, args); +} + +static int btf_type_seq_show_flags(const struct btf *btf, u32 type_id, + void *obj, struct seq_file *m, u64 flags) +{ + struct btf_show sseq; + + sseq.target = m; + sseq.showfn = btf_seq_show; + sseq.flags = flags; + + btf_type_show(btf, type_id, obj, &sseq); + + return sseq.state.status; +} + void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj, struct seq_file *m) { - const struct btf_type *t = btf_type_by_id(btf, type_id); + (void) btf_type_seq_show_flags(btf, type_id, obj, m, + BTF_SHOW_NONAME | BTF_SHOW_COMPACT | + BTF_SHOW_ZERO | BTF_SHOW_UNSAFE); +} + +struct btf_show_snprintf { + struct btf_show show; + int len_left; /* space left in string */ + int len; /* length we would have written */ +}; + +static void btf_snprintf_show(struct btf_show *show, const char *fmt, + va_list args) +{ + struct btf_show_snprintf *ssnprintf = (struct btf_show_snprintf *)show; + int len; + + len = vsnprintf(show->target, ssnprintf->len_left, fmt, args); + + if (len < 0) { + ssnprintf->len_left = 0; + ssnprintf->len = len; + } else if (len > ssnprintf->len_left) { + /* no space, drive on to get length we would have written */ + ssnprintf->len_left = 0; + ssnprintf->len += len; + } else { + ssnprintf->len_left -= len; + ssnprintf->len += len; + show->target += len; + } +} + +int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj, + char *buf, int len, u64 flags) +{ + struct btf_show_snprintf ssnprintf; + + ssnprintf.show.target = buf; + ssnprintf.show.flags = flags; + ssnprintf.show.showfn = btf_snprintf_show; + ssnprintf.len_left = len; + ssnprintf.len = 0; + + btf_type_show(btf, type_id, obj, (struct btf_show *)&ssnprintf); + + /* If we encontered an error, return it. */ + if (ssnprintf.show.state.status) + return ssnprintf.show.state.status; - btf_type_ops(t)->seq_show(btf, t, type_id, obj, 0, m); + /* Otherwise return length we would have written */ + return ssnprintf.len; } #ifdef CONFIG_PROC_FS |