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-rw-r--r--kernel/bpf/verifier.c87
1 files changed, 32 insertions, 55 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index c5ecb6147ea2..28767cd43046 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1920,6 +1920,19 @@ static int check_stack_write(struct bpf_verifier_env *env,
cur = env->cur_state->frame[env->cur_state->curframe];
if (value_regno >= 0)
reg = &cur->regs[value_regno];
+ if (!env->allow_ptr_leaks) {
+ bool sanitize = reg && is_spillable_regtype(reg->type);
+
+ for (i = 0; i < size; i++) {
+ if (state->stack[spi].slot_type[i] == STACK_INVALID) {
+ sanitize = true;
+ break;
+ }
+ }
+
+ if (sanitize)
+ env->insn_aux_data[insn_idx].sanitize_stack_spill = true;
+ }
if (reg && size == BPF_REG_SIZE && register_is_const(reg) &&
!register_is_null(reg) && env->allow_ptr_leaks) {
@@ -1942,47 +1955,10 @@ static int check_stack_write(struct bpf_verifier_env *env,
verbose(env, "invalid size of register spill\n");
return -EACCES;
}
-
if (state != cur && reg->type == PTR_TO_STACK) {
verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
return -EINVAL;
}
-
- if (!env->allow_ptr_leaks) {
- bool sanitize = false;
-
- if (state->stack[spi].slot_type[0] == STACK_SPILL &&
- register_is_const(&state->stack[spi].spilled_ptr))
- sanitize = true;
- for (i = 0; i < BPF_REG_SIZE; i++)
- if (state->stack[spi].slot_type[i] == STACK_MISC) {
- sanitize = true;
- break;
- }
- if (sanitize) {
- int *poff = &env->insn_aux_data[insn_idx].sanitize_stack_off;
- int soff = (-spi - 1) * BPF_REG_SIZE;
-
- /* detected reuse of integer stack slot with a pointer
- * which means either llvm is reusing stack slot or
- * an attacker is trying to exploit CVE-2018-3639
- * (speculative store bypass)
- * Have to sanitize that slot with preemptive
- * store of zero.
- */
- if (*poff && *poff != soff) {
- /* disallow programs where single insn stores
- * into two different stack slots, since verifier
- * cannot sanitize them
- */
- verbose(env,
- "insn %d cannot access two stack slots fp%d and fp%d",
- insn_idx, *poff, soff);
- return -EINVAL;
- }
- *poff = soff;
- }
- }
save_register_state(state, spi, reg);
} else {
u8 type = STACK_MISC;
@@ -8854,35 +8830,33 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
for (i = 0; i < insn_cnt; i++, insn++) {
bpf_convert_ctx_access_t convert_ctx_access;
+ bool ctx_access;
if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
- insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
+ insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) {
type = BPF_READ;
- else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
- insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
- insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
- insn->code == (BPF_STX | BPF_MEM | BPF_DW))
+ ctx_access = true;
+ } else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
+ insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
+ insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
+ insn->code == (BPF_STX | BPF_MEM | BPF_DW) ||
+ insn->code == (BPF_ST | BPF_MEM | BPF_B) ||
+ insn->code == (BPF_ST | BPF_MEM | BPF_H) ||
+ insn->code == (BPF_ST | BPF_MEM | BPF_W) ||
+ insn->code == (BPF_ST | BPF_MEM | BPF_DW)) {
type = BPF_WRITE;
- else
+ ctx_access = BPF_CLASS(insn->code) == BPF_STX;
+ } else {
continue;
+ }
if (type == BPF_WRITE &&
- env->insn_aux_data[i + delta].sanitize_stack_off) {
+ env->insn_aux_data[i + delta].sanitize_stack_spill) {
struct bpf_insn patch[] = {
- /* Sanitize suspicious stack slot with zero.
- * There are no memory dependencies for this store,
- * since it's only using frame pointer and immediate
- * constant of zero
- */
- BPF_ST_MEM(BPF_DW, BPF_REG_FP,
- env->insn_aux_data[i + delta].sanitize_stack_off,
- 0),
- /* the original STX instruction will immediately
- * overwrite the same stack slot with appropriate value
- */
*insn,
+ BPF_ST_NOSPEC(),
};
cnt = ARRAY_SIZE(patch);
@@ -8896,6 +8870,9 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
continue;
}
+ if (!ctx_access)
+ continue;
+
switch (env->insn_aux_data[i + delta].ptr_type) {
case PTR_TO_CTX:
if (!ops->convert_ctx_access)