struct verifier_state_list **explored_states; /* search pruning optimization */
struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
u32 used_map_cnt; /* number of used maps */
+ bool allow_ptr_leaks;
};
/* verbose verifier prints what it's seeing
* verbose() is used to dump the verification trace to the log, so the user
* can figure out what's wrong with the program
*/
-static void verbose(const char *fmt, ...)
+static __printf(1, 2) void verbose(const char *fmt, ...)
{
va_list args;
[CONST_IMM] = "imm",
};
+static const struct {
+ int map_type;
+ int func_id;
+} func_limit[] = {
+ {BPF_MAP_TYPE_PROG_ARRAY, BPF_FUNC_tail_call},
+ {BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_read},
+ {BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_output},
+};
+
static void print_verifier_state(struct verifier_env *env)
{
enum bpf_reg_type t;
[BPF_ALU64] = "alu64",
};
-static const char *const bpf_alu_string[] = {
+static const char *const bpf_alu_string[16] = {
[BPF_ADD >> 4] = "+=",
[BPF_SUB >> 4] = "-=",
[BPF_MUL >> 4] = "*=",
[BPF_DW >> 3] = "u64",
};
-static const char *const bpf_jmp_string[] = {
+static const char *const bpf_jmp_string[16] = {
[BPF_JA >> 4] = "jmp",
[BPF_JEQ >> 4] = "==",
[BPF_JGT >> 4] = ">",
return -EINVAL;
}
+static bool is_spillable_regtype(enum bpf_reg_type type)
+{
+ switch (type) {
+ case PTR_TO_MAP_VALUE:
+ case PTR_TO_MAP_VALUE_OR_NULL:
+ case PTR_TO_STACK:
+ case PTR_TO_CTX:
+ case FRAME_PTR:
+ case CONST_PTR_TO_MAP:
+ return true;
+ default:
+ return false;
+ }
+}
+
/* check_stack_read/write functions track spill/fill of registers,
* stack boundary and alignment are checked in check_mem_access()
*/
*/
if (value_regno >= 0 &&
- (state->regs[value_regno].type == PTR_TO_MAP_VALUE ||
- state->regs[value_regno].type == PTR_TO_STACK ||
- state->regs[value_regno].type == PTR_TO_CTX)) {
+ is_spillable_regtype(state->regs[value_regno].type)) {
/* register containing pointer is being spilled into stack */
if (size != BPF_REG_SIZE) {
return -EACCES;
}
+static bool is_pointer_value(struct verifier_env *env, int regno)
+{
+ if (env->allow_ptr_leaks)
+ return false;
+
+ switch (env->cur_state.regs[regno].type) {
+ case UNKNOWN_VALUE:
+ case CONST_IMM:
+ return false;
+ default:
+ return true;
+ }
+}
+
/* 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
struct verifier_state *state = &env->cur_state;
int size, err = 0;
+ if (state->regs[regno].type == PTR_TO_STACK)
+ off += state->regs[regno].imm;
+
size = bpf_size_to_bytes(bpf_size);
if (size < 0)
return size;
}
if (state->regs[regno].type == PTR_TO_MAP_VALUE) {
+ if (t == BPF_WRITE && value_regno >= 0 &&
+ is_pointer_value(env, value_regno)) {
+ verbose("R%d leaks addr into map\n", value_regno);
+ return -EACCES;
+ }
err = check_map_access(env, regno, off, size);
if (!err && t == BPF_READ && value_regno >= 0)
mark_reg_unknown_value(state->regs, value_regno);
} else if (state->regs[regno].type == PTR_TO_CTX) {
+ if (t == BPF_WRITE && value_regno >= 0 &&
+ is_pointer_value(env, value_regno)) {
+ verbose("R%d leaks addr into ctx\n", value_regno);
+ return -EACCES;
+ }
err = check_ctx_access(env, off, size, t);
if (!err && t == BPF_READ && value_regno >= 0)
mark_reg_unknown_value(state->regs, value_regno);
- } else if (state->regs[regno].type == FRAME_PTR) {
+ } else if (state->regs[regno].type == FRAME_PTR ||
+ state->regs[regno].type == PTR_TO_STACK) {
if (off >= 0 || off < -MAX_BPF_STACK) {
verbose("invalid stack off=%d size=%d\n", off, size);
return -EACCES;
}
- if (t == BPF_WRITE)
+ if (t == BPF_WRITE) {
+ if (!env->allow_ptr_leaks &&
+ state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL &&
+ size != BPF_REG_SIZE) {
+ verbose("attempt to corrupt spilled pointer on stack\n");
+ return -EACCES;
+ }
err = check_stack_write(state, off, size, value_regno);
- else
+ } else {
err = check_stack_read(state, off, size, value_regno);
+ }
} else {
verbose("R%d invalid mem access '%s'\n",
regno, reg_type_str[state->regs[regno].type]);
return -EACCES;
}
- if (arg_type == ARG_ANYTHING)
+ if (arg_type == ARG_ANYTHING) {
+ if (is_pointer_value(env, regno)) {
+ verbose("R%d leaks addr into helper function\n", regno);
+ return -EACCES;
+ }
return 0;
+ }
if (arg_type == ARG_PTR_TO_STACK || arg_type == ARG_PTR_TO_MAP_KEY ||
arg_type == ARG_PTR_TO_MAP_VALUE) {
return err;
}
+static int check_map_func_compatibility(struct bpf_map *map, int func_id)
+{
+ bool bool_map, bool_func;
+ int i;
+
+ if (!map)
+ return 0;
+
+ for (i = 0; i < ARRAY_SIZE(func_limit); i++) {
+ bool_map = (map->map_type == func_limit[i].map_type);
+ bool_func = (func_id == func_limit[i].func_id);
+ /* only when map & func pair match it can continue.
+ * don't allow any other map type to be passed into
+ * the special func;
+ */
+ if (bool_func && bool_map != bool_func)
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
static int check_call(struct verifier_env *env, int func_id)
{
struct verifier_state *state = &env->cur_state;
fn->ret_type, func_id);
return -EINVAL;
}
+
+ err = check_map_func_compatibility(map, func_id);
+ if (err)
+ return err;
+
return 0;
}
/* check validity of 32-bit and 64-bit arithmetic operations */
-static int check_alu_op(struct reg_state *regs, struct bpf_insn *insn)
+static int check_alu_op(struct verifier_env *env, struct bpf_insn *insn)
{
+ struct reg_state *regs = env->cur_state.regs;
u8 opcode = BPF_OP(insn->code);
int err;
if (err)
return err;
+ if (is_pointer_value(env, insn->dst_reg)) {
+ verbose("R%d pointer arithmetic prohibited\n",
+ insn->dst_reg);
+ return -EACCES;
+ }
+
/* check dest operand */
err = check_reg_arg(regs, insn->dst_reg, DST_OP);
if (err)
*/
regs[insn->dst_reg] = regs[insn->src_reg];
} else {
+ if (is_pointer_value(env, insn->src_reg)) {
+ verbose("R%d partial copy of pointer\n",
+ insn->src_reg);
+ return -EACCES;
+ }
regs[insn->dst_reg].type = UNKNOWN_VALUE;
regs[insn->dst_reg].map_ptr = NULL;
}
return -EINVAL;
}
+ if ((opcode == BPF_LSH || opcode == BPF_RSH ||
+ opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
+ int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
+
+ if (insn->imm < 0 || insn->imm >= size) {
+ verbose("invalid shift %d\n", insn->imm);
+ return -EINVAL;
+ }
+ }
+
/* pattern match 'bpf_add Rx, imm' instruction */
if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 &&
regs[insn->dst_reg].type == FRAME_PTR &&
- BPF_SRC(insn->code) == BPF_K)
+ BPF_SRC(insn->code) == BPF_K) {
stack_relative = true;
+ } else if (is_pointer_value(env, insn->dst_reg)) {
+ verbose("R%d pointer arithmetic prohibited\n",
+ insn->dst_reg);
+ return -EACCES;
+ } else if (BPF_SRC(insn->code) == BPF_X &&
+ is_pointer_value(env, insn->src_reg)) {
+ verbose("R%d pointer arithmetic prohibited\n",
+ insn->src_reg);
+ return -EACCES;
+ }
/* check dest operand */
err = check_reg_arg(regs, insn->dst_reg, DST_OP);
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
if (err)
return err;
+
+ if (is_pointer_value(env, insn->src_reg)) {
+ verbose("R%d pointer comparison prohibited\n",
+ insn->src_reg);
+ return -EACCES;
+ }
} else {
if (insn->src_reg != BPF_REG_0) {
verbose("BPF_JMP uses reserved fields\n");
regs[insn->dst_reg].type = CONST_IMM;
regs[insn->dst_reg].imm = 0;
}
+ } else if (is_pointer_value(env, insn->dst_reg)) {
+ verbose("R%d pointer comparison prohibited\n", insn->dst_reg);
+ return -EACCES;
} else if (BPF_SRC(insn->code) == BPF_K &&
(opcode == BPF_JEQ || opcode == BPF_JNE)) {
}
if (class == BPF_ALU || class == BPF_ALU64) {
- err = check_alu_op(regs, insn);
+ err = check_alu_op(env, insn);
if (err)
return err;
}
} else if (class == BPF_STX) {
+ enum bpf_reg_type dst_reg_type;
+
if (BPF_MODE(insn->code) == BPF_XADD) {
err = check_xadd(env, insn);
if (err)
continue;
}
- if (BPF_MODE(insn->code) != BPF_MEM ||
- insn->imm != 0) {
- verbose("BPF_STX uses reserved fields\n");
- return -EINVAL;
- }
/* check src1 operand */
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
if (err)
if (err)
return err;
+ dst_reg_type = regs[insn->dst_reg].type;
+
/* check that memory (dst_reg + off) is writeable */
err = check_mem_access(env, insn->dst_reg, insn->off,
BPF_SIZE(insn->code), BPF_WRITE,
if (err)
return err;
+ if (insn->imm == 0) {
+ insn->imm = dst_reg_type;
+ } else if (dst_reg_type != insn->imm &&
+ (dst_reg_type == PTR_TO_CTX ||
+ insn->imm == PTR_TO_CTX)) {
+ verbose("same insn cannot be used with different pointers\n");
+ return -EINVAL;
+ }
+
} else if (class == BPF_ST) {
if (BPF_MODE(insn->code) != BPF_MEM ||
insn->src_reg != BPF_REG_0) {
if (err)
return err;
+ if (is_pointer_value(env, BPF_REG_0)) {
+ verbose("R0 leaks addr as return value\n");
+ return -EACCES;
+ }
+
process_bpf_exit:
insn_idx = pop_stack(env, &prev_insn_idx);
if (insn_idx < 0) {
for (i = 0; i < insn_cnt; i++, insn++) {
if (BPF_CLASS(insn->code) == BPF_LDX &&
- (BPF_MODE(insn->code) != BPF_MEM ||
- insn->imm != 0)) {
+ (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
verbose("BPF_LDX uses reserved fields\n");
return -EINVAL;
}
+ if (BPF_CLASS(insn->code) == BPF_STX &&
+ ((BPF_MODE(insn->code) != BPF_MEM &&
+ BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) {
+ verbose("BPF_STX uses reserved fields\n");
+ return -EINVAL;
+ }
+
if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
struct bpf_map *map;
struct fd f;
}
f = fdget(insn->imm);
-
- map = bpf_map_get(f);
+ map = __bpf_map_get(f);
if (IS_ERR(map)) {
verbose("fd %d is not pointing to valid bpf_map\n",
insn->imm);
* will be used by the valid program until it's unloaded
* and all maps are released in free_bpf_prog_info()
*/
- atomic_inc(&map->refcnt);
-
+ bpf_map_inc(map, false);
fdput(f);
next_insn:
insn++;
/* adjust offset of jmps if necessary */
if (i < pos && i + insn->off + 1 > pos)
insn->off += delta;
- else if (i > pos && i + insn->off + 1 < pos)
+ else if (i > pos + delta && i + insn->off + 1 <= pos + delta)
insn->off -= delta;
}
}
struct bpf_prog *new_prog;
u32 cnt;
int i;
+ enum bpf_access_type type;
if (!env->prog->aux->ops->convert_ctx_access)
return 0;
for (i = 0; i < insn_cnt; i++, insn++) {
- if (insn->code != (BPF_LDX | BPF_MEM | BPF_W))
+ if (insn->code == (BPF_LDX | BPF_MEM | BPF_W))
+ type = BPF_READ;
+ else if (insn->code == (BPF_STX | BPF_MEM | BPF_W))
+ type = BPF_WRITE;
+ else
continue;
if (insn->imm != PTR_TO_CTX) {
}
cnt = env->prog->aux->ops->
- convert_ctx_access(insn->dst_reg, insn->src_reg,
- insn->off, insn_buf);
+ convert_ctx_access(type, insn->dst_reg, insn->src_reg,
+ insn->off, insn_buf, env->prog);
if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
verbose("bpf verifier is misconfigured\n");
return -EINVAL;
if (ret < 0)
goto skip_full_check;
+ env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
+
ret = do_check(env);
skip_full_check:
Code Review / kvmfornfv.git / blobdiff