diff options
| -rw-r--r-- | include/linux/bpf.h | 17 | ||||
| -rw-r--r-- | include/linux/bpf_verifier.h | 4 | ||||
| -rw-r--r-- | kernel/bpf/btf.c | 190 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 88 | ||||
| -rw-r--r-- | kernel/trace/bpf_trace.c | 2 |
5 files changed, 296 insertions, 5 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index f916380675dd..028555fcd10d 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -16,6 +16,7 @@ #include <linux/u64_stats_sync.h> struct bpf_verifier_env; +struct bpf_verifier_log; struct perf_event; struct bpf_prog; struct bpf_map; @@ -281,6 +282,7 @@ enum bpf_reg_type { PTR_TO_TCP_SOCK_OR_NULL, /* reg points to struct tcp_sock or NULL */ PTR_TO_TP_BUFFER, /* reg points to a writable raw tp's buffer */ PTR_TO_XDP_SOCK, /* reg points to struct xdp_sock */ + PTR_TO_BTF_ID, /* reg points to kernel struct */ }; /* The information passed from prog-specific *_is_valid_access @@ -288,7 +290,11 @@ enum bpf_reg_type { */ struct bpf_insn_access_aux { enum bpf_reg_type reg_type; - int ctx_field_size; + union { + int ctx_field_size; + u32 btf_id; + }; + struct bpf_verifier_log *log; /* for verbose logs */ }; static inline void @@ -483,6 +489,7 @@ struct bpf_event_entry { bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp); int bpf_prog_calc_tag(struct bpf_prog *fp); +const char *kernel_type_name(u32 btf_type_id); const struct bpf_func_proto *bpf_get_trace_printk_proto(void); @@ -748,6 +755,14 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr, int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog, const union bpf_attr *kattr, union bpf_attr __user *uattr); +bool btf_ctx_access(int off, int size, enum bpf_access_type type, + const struct bpf_prog *prog, + struct bpf_insn_access_aux *info); +int btf_struct_access(struct bpf_verifier_log *log, + const struct btf_type *t, int off, int size, + enum bpf_access_type atype, + u32 *next_btf_id); + #else /* !CONFIG_BPF_SYSCALL */ static inline struct bpf_prog *bpf_prog_get(u32 ufd) { diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 713efae62e96..6e7284ea1468 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -52,6 +52,8 @@ struct bpf_reg_state { */ struct bpf_map *map_ptr; + u32 btf_id; /* for PTR_TO_BTF_ID */ + /* Max size from any of the above. */ unsigned long raw; }; @@ -399,6 +401,8 @@ __printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt, va_list args); __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env, const char *fmt, ...); +__printf(2, 3) void bpf_log(struct bpf_verifier_log *log, + const char *fmt, ...); static inline struct bpf_func_state *cur_func(struct bpf_verifier_env *env) { diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index ddeab1e8d21e..271d27cd427f 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3436,6 +3436,196 @@ errout: return ERR_PTR(err); } +extern struct btf *btf_vmlinux; + +bool btf_ctx_access(int off, int size, enum bpf_access_type type, + const struct bpf_prog *prog, + struct bpf_insn_access_aux *info) +{ + struct bpf_verifier_log *log = info->log; + u32 btf_id = prog->aux->attach_btf_id; + const struct btf_param *args; + const struct btf_type *t; + const char prefix[] = "btf_trace_"; + const char *tname; + u32 nr_args, arg; + + if (!btf_id) + return true; + + if (IS_ERR(btf_vmlinux)) { + bpf_log(log, "btf_vmlinux is malformed\n"); + return false; + } + + t = btf_type_by_id(btf_vmlinux, btf_id); + if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF) { + bpf_log(log, "btf_id is invalid\n"); + return false; + } + + tname = __btf_name_by_offset(btf_vmlinux, t->name_off); + if (strncmp(prefix, tname, sizeof(prefix) - 1)) { + bpf_log(log, "btf_id points to wrong type name %s\n", tname); + return false; + } + tname += sizeof(prefix) - 1; + + t = btf_type_by_id(btf_vmlinux, t->type); + if (!btf_type_is_ptr(t)) + return false; + t = btf_type_by_id(btf_vmlinux, t->type); + if (!btf_type_is_func_proto(t)) + return false; + + if (off % 8) { + bpf_log(log, "raw_tp '%s' offset %d is not multiple of 8\n", + tname, off); + return false; + } + arg = off / 8; + args = (const struct btf_param *)(t + 1); + /* skip first 'void *__data' argument in btf_trace_##name typedef */ + args++; + nr_args = btf_type_vlen(t) - 1; + if (arg >= nr_args) { + bpf_log(log, "raw_tp '%s' doesn't have %d-th argument\n", + tname, arg); + return false; + } + + t = btf_type_by_id(btf_vmlinux, args[arg].type); + /* skip modifiers */ + while (btf_type_is_modifier(t)) + t = btf_type_by_id(btf_vmlinux, t->type); + if (btf_type_is_int(t)) + /* accessing a scalar */ + return true; + if (!btf_type_is_ptr(t)) { + bpf_log(log, + "raw_tp '%s' arg%d '%s' has type %s. Only pointer access is allowed\n", + tname, arg, + __btf_name_by_offset(btf_vmlinux, t->name_off), + btf_kind_str[BTF_INFO_KIND(t->info)]); + return false; + } + if (t->type == 0) + /* This is a pointer to void. + * It is the same as scalar from the verifier safety pov. + * No further pointer walking is allowed. + */ + return true; + + /* this is a pointer to another type */ + info->reg_type = PTR_TO_BTF_ID; + info->btf_id = t->type; + + t = btf_type_by_id(btf_vmlinux, t->type); + /* skip modifiers */ + while (btf_type_is_modifier(t)) + t = btf_type_by_id(btf_vmlinux, t->type); + if (!btf_type_is_struct(t)) { + bpf_log(log, + "raw_tp '%s' arg%d type %s is not a struct\n", + tname, arg, btf_kind_str[BTF_INFO_KIND(t->info)]); + return false; + } + bpf_log(log, "raw_tp '%s' arg%d has btf_id %d type %s '%s'\n", + tname, arg, info->btf_id, btf_kind_str[BTF_INFO_KIND(t->info)], + __btf_name_by_offset(btf_vmlinux, t->name_off)); + return true; +} + +int btf_struct_access(struct bpf_verifier_log *log, + const struct btf_type *t, int off, int size, + enum bpf_access_type atype, + u32 *next_btf_id) +{ + const struct btf_member *member; + const struct btf_type *mtype; + const char *tname, *mname; + int i, moff = 0, msize; + +again: + tname = __btf_name_by_offset(btf_vmlinux, t->name_off); + if (!btf_type_is_struct(t)) { + bpf_log(log, "Type '%s' is not a struct", tname); + return -EINVAL; + } + + for_each_member(i, t, member) { + /* offset of the field in bits */ + moff = btf_member_bit_offset(t, member); + + if (btf_member_bitfield_size(t, member)) + /* bitfields are not supported yet */ + continue; + + if (off + size <= moff / 8) + /* won't find anything, field is already too far */ + break; + + /* type of the field */ + mtype = btf_type_by_id(btf_vmlinux, member->type); + mname = __btf_name_by_offset(btf_vmlinux, member->name_off); + + /* skip modifiers */ + while (btf_type_is_modifier(mtype)) + mtype = btf_type_by_id(btf_vmlinux, mtype->type); + + if (btf_type_is_array(mtype)) + /* array deref is not supported yet */ + continue; + + if (!btf_type_has_size(mtype) && !btf_type_is_ptr(mtype)) { + bpf_log(log, "field %s doesn't have size\n", mname); + return -EFAULT; + } + if (btf_type_is_ptr(mtype)) + msize = 8; + else + msize = mtype->size; + if (off >= moff / 8 + msize) + /* no overlap with member, keep iterating */ + continue; + /* the 'off' we're looking for is either equal to start + * of this field or inside of this struct + */ + if (btf_type_is_struct(mtype)) { + /* our field must be inside that union or struct */ + t = mtype; + + /* adjust offset we're looking for */ + off -= moff / 8; + goto again; + } + if (msize != size) { + /* field access size doesn't match */ + bpf_log(log, + "cannot access %d bytes in struct %s field %s that has size %d\n", + size, tname, mname, msize); + return -EACCES; + } + + if (btf_type_is_ptr(mtype)) { + const struct btf_type *stype; + + stype = btf_type_by_id(btf_vmlinux, mtype->type); + /* skip modifiers */ + while (btf_type_is_modifier(stype)) + stype = btf_type_by_id(btf_vmlinux, stype->type); + if (btf_type_is_struct(stype)) { + *next_btf_id = mtype->type; + return PTR_TO_BTF_ID; + } + } + /* all other fields are treated as scalars */ + return SCALAR_VALUE; + } + bpf_log(log, "struct %s doesn't have field at offset %d\n", tname, off); + return -EINVAL; +} + void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj, struct seq_file *m) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 466b3b19de4d..42a463e09761 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -286,6 +286,19 @@ __printf(2, 3) static void verbose(void *private_data, const char *fmt, ...) va_end(args); } +__printf(2, 3) void bpf_log(struct bpf_verifier_log *log, + const char *fmt, ...) +{ + va_list args; + + if (!bpf_verifier_log_needed(log)) + return; + + va_start(args, fmt); + bpf_verifier_vlog(log, fmt, args); + va_end(args); +} + static const char *ltrim(const char *s) { while (isspace(*s)) @@ -406,6 +419,7 @@ static const char * const reg_type_str[] = { [PTR_TO_TCP_SOCK_OR_NULL] = "tcp_sock_or_null", [PTR_TO_TP_BUFFER] = "tp_buffer", [PTR_TO_XDP_SOCK] = "xdp_sock", + [PTR_TO_BTF_ID] = "ptr_", }; static char slot_type_char[] = { @@ -436,6 +450,12 @@ static struct bpf_func_state *func(struct bpf_verifier_env *env, return cur->frame[reg->frameno]; } +const char *kernel_type_name(u32 id) +{ + return btf_name_by_offset(btf_vmlinux, + btf_type_by_id(btf_vmlinux, id)->name_off); +} + static void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_state *state) { @@ -460,6 +480,8 @@ static void print_verifier_state(struct bpf_verifier_env *env, /* reg->off should be 0 for SCALAR_VALUE */ verbose(env, "%lld", reg->var_off.value + reg->off); } else { + if (t == PTR_TO_BTF_ID) + verbose(env, "%s", kernel_type_name(reg->btf_id)); verbose(env, "(id=%d", reg->id); if (reg_type_may_be_refcounted_or_null(t)) verbose(env, ",ref_obj_id=%d", reg->ref_obj_id); @@ -2337,10 +2359,12 @@ static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, /* check access to 'struct bpf_context' fields. Supports fixed offsets only */ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, - enum bpf_access_type t, enum bpf_reg_type *reg_type) + enum bpf_access_type t, enum bpf_reg_type *reg_type, + u32 *btf_id) { struct bpf_insn_access_aux info = { .reg_type = *reg_type, + .log = &env->log, }; if (env->ops->is_valid_access && @@ -2354,7 +2378,10 @@ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, */ *reg_type = info.reg_type; - env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; + if (*reg_type == PTR_TO_BTF_ID) + *btf_id = info.btf_id; + else + env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; /* remember the offset of last byte accessed in ctx */ if (env->prog->aux->max_ctx_offset < off + size) env->prog->aux->max_ctx_offset = off + size; @@ -2780,6 +2807,53 @@ static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val) return 0; } +static int check_ptr_to_btf_access(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, + int regno, int off, int size, + enum bpf_access_type atype, + int value_regno) +{ + struct bpf_reg_state *reg = regs + regno; + const struct btf_type *t = btf_type_by_id(btf_vmlinux, reg->btf_id); + const char *tname = btf_name_by_offset(btf_vmlinux, t->name_off); + u32 btf_id; + int ret; + + if (atype != BPF_READ) { + verbose(env, "only read is supported\n"); + return -EACCES; + } + + if (off < 0) { + verbose(env, + "R%d is ptr_%s invalid negative access: off=%d\n", + regno, tname, off); + return -EACCES; + } + if (!tnum_is_const(reg->var_off) || reg->var_off.value) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, + "R%d is ptr_%s invalid variable offset: off=%d, var_off=%s\n", + regno, tname, off, tn_buf); + return -EACCES; + } + + ret = btf_struct_access(&env->log, t, off, size, atype, &btf_id); + if (ret < 0) + return ret; + + if (ret == SCALAR_VALUE) { + mark_reg_unknown(env, regs, value_regno); + return 0; + } + mark_reg_known_zero(env, regs, value_regno); + regs[value_regno].type = PTR_TO_BTF_ID; + regs[value_regno].btf_id = btf_id; + return 0; +} + /* check whether memory at (regno + off) is accessible for t = (read | write) * if t==write, value_regno is a register which value is stored into memory * if t==read, value_regno is a register which will receive the value from memory @@ -2840,6 +2914,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn } } else if (reg->type == PTR_TO_CTX) { enum bpf_reg_type reg_type = SCALAR_VALUE; + u32 btf_id = 0; if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) { @@ -2851,7 +2926,9 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn if (err < 0) return err; - err = check_ctx_access(env, insn_idx, off, size, t, ®_type); + err = check_ctx_access(env, insn_idx, off, size, t, ®_type, &btf_id); + if (err) + verbose_linfo(env, insn_idx, "; "); if (!err && t == BPF_READ && value_regno >= 0) { /* ctx access returns either a scalar, or a * PTR_TO_PACKET[_META,_END]. In the latter @@ -2870,6 +2947,8 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn * a sub-register. */ regs[value_regno].subreg_def = DEF_NOT_SUBREG; + if (reg_type == PTR_TO_BTF_ID) + regs[value_regno].btf_id = btf_id; } regs[value_regno].type = reg_type; } @@ -2929,6 +3008,9 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn err = check_tp_buffer_access(env, reg, regno, off, size); if (!err && t == BPF_READ && value_regno >= 0) mark_reg_unknown(env, regs, value_regno); + } else if (reg->type == PTR_TO_BTF_ID) { + err = check_ptr_to_btf_access(env, regs, regno, off, size, t, + value_regno); } else { verbose(env, "R%d invalid mem access '%s'\n", regno, reg_type_str[reg->type]); diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 44bd08f2443b..6221e8c6ecc3 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1074,7 +1074,7 @@ static bool raw_tp_prog_is_valid_access(int off, int size, return false; if (off % size != 0) return false; - return true; + return btf_ctx_access(off, size, type, prog, info); } const struct bpf_verifier_ops raw_tracepoint_verifier_ops = { |