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-rw-r--r--kernel/bpf/verifier.c90
1 files changed, 65 insertions, 25 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 8d1786357a09..6c13d86569a6 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1378,6 +1378,23 @@ static bool register_is_null(struct bpf_reg_state *reg)
return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
}
+static bool register_is_const(struct bpf_reg_state *reg)
+{
+ return reg->type == SCALAR_VALUE && tnum_is_const(reg->var_off);
+}
+
+static void save_register_state(struct bpf_func_state *state,
+ int spi, struct bpf_reg_state *reg)
+{
+ int i;
+
+ state->stack[spi].spilled_ptr = *reg;
+ state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
+
+ for (i = 0; i < BPF_REG_SIZE; i++)
+ state->stack[spi].slot_type[i] = STACK_SPILL;
+}
+
/* check_stack_read/write functions track spill/fill of registers,
* stack boundary and alignment are checked in check_mem_access()
*/
@@ -1387,7 +1404,7 @@ static int check_stack_write(struct bpf_verifier_env *env,
{
struct bpf_func_state *cur; /* state of the current function */
int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
- enum bpf_reg_type type;
+ struct bpf_reg_state *reg = NULL;
err = realloc_func_state(state, round_up(slot + 1, BPF_REG_SIZE),
state->acquired_refs, true);
@@ -1404,27 +1421,37 @@ static int check_stack_write(struct bpf_verifier_env *env,
}
cur = env->cur_state->frame[env->cur_state->curframe];
- if (value_regno >= 0 &&
- is_spillable_regtype((type = cur->regs[value_regno].type))) {
+ if (value_regno >= 0)
+ reg = &cur->regs[value_regno];
+ if (reg && size == BPF_REG_SIZE && register_is_const(reg) &&
+ !register_is_null(reg) && env->allow_ptr_leaks) {
+ save_register_state(state, spi, reg);
+ } else if (reg && is_spillable_regtype(reg->type)) {
/* register containing pointer is being spilled into stack */
if (size != BPF_REG_SIZE) {
+ verbose_linfo(env, insn_idx, "; ");
verbose(env, "invalid size of register spill\n");
return -EACCES;
}
- if (state != cur && type == PTR_TO_STACK) {
+ if (state != cur && reg->type == PTR_TO_STACK) {
verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
return -EINVAL;
}
- /* save register state */
- state->stack[spi].spilled_ptr = cur->regs[value_regno];
- state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
+ if (!env->allow_ptr_leaks) {
+ bool sanitize = false;
- for (i = 0; i < BPF_REG_SIZE; i++) {
- if (state->stack[spi].slot_type[i] == STACK_MISC &&
- !env->allow_ptr_leaks) {
+ 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;
@@ -1447,8 +1474,8 @@ static int check_stack_write(struct bpf_verifier_env *env,
}
*poff = soff;
}
- state->stack[spi].slot_type[i] = STACK_SPILL;
}
+ save_register_state(state, spi, reg);
} else {
u8 type = STACK_MISC;
@@ -1471,8 +1498,7 @@ static int check_stack_write(struct bpf_verifier_env *env,
state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
/* when we zero initialize stack slots mark them as such */
- if (value_regno >= 0 &&
- register_is_null(&cur->regs[value_regno]))
+ if (reg && register_is_null(reg))
type = STACK_ZERO;
/* Mark slots affected by this stack write. */
@@ -1490,6 +1516,7 @@ static int check_stack_read(struct bpf_verifier_env *env,
struct bpf_verifier_state *vstate = env->cur_state;
struct bpf_func_state *state = vstate->frame[vstate->curframe];
int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
+ struct bpf_reg_state *reg;
u8 *stype;
if (reg_state->allocated_stack <= slot) {
@@ -1498,11 +1525,21 @@ static int check_stack_read(struct bpf_verifier_env *env,
return -EACCES;
}
stype = reg_state->stack[spi].slot_type;
+ reg = &reg_state->stack[spi].spilled_ptr;
if (stype[0] == STACK_SPILL) {
if (size != BPF_REG_SIZE) {
- verbose(env, "invalid size of register spill\n");
- return -EACCES;
+ if (reg->type != SCALAR_VALUE) {
+ verbose_linfo(env, env->insn_idx, "; ");
+ verbose(env, "invalid size of register fill\n");
+ return -EACCES;
+ }
+ if (value_regno >= 0) {
+ mark_reg_unknown(env, state->regs, value_regno);
+ state->regs[value_regno].live |= REG_LIVE_WRITTEN;
+ }
+ mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
+ return 0;
}
for (i = 1; i < BPF_REG_SIZE; i++) {
if (stype[(slot - i) % BPF_REG_SIZE] != STACK_SPILL) {
@@ -1513,17 +1550,14 @@ static int check_stack_read(struct bpf_verifier_env *env,
if (value_regno >= 0) {
/* restore register state from stack */
- state->regs[value_regno] = reg_state->stack[spi].spilled_ptr;
+ state->regs[value_regno] = *reg;
/* mark reg as written since spilled pointer state likely
* has its liveness marks cleared by is_state_visited()
* which resets stack/reg liveness for state transitions
*/
state->regs[value_regno].live |= REG_LIVE_WRITTEN;
}
- mark_reg_read(env, &reg_state->stack[spi].spilled_ptr,
- reg_state->stack[spi].spilled_ptr.parent,
- REG_LIVE_READ64);
- return 0;
+ mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
} else {
int zeros = 0;
@@ -1538,9 +1572,7 @@ static int check_stack_read(struct bpf_verifier_env *env,
off, i, size);
return -EACCES;
}
- mark_reg_read(env, &reg_state->stack[spi].spilled_ptr,
- reg_state->stack[spi].spilled_ptr.parent,
- REG_LIVE_READ64);
+ mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
if (value_regno >= 0) {
if (zeros == size) {
/* any size read into register is zero extended,
@@ -1553,8 +1585,8 @@ static int check_stack_read(struct bpf_verifier_env *env,
}
state->regs[value_regno].live |= REG_LIVE_WRITTEN;
}
- return 0;
}
+ return 0;
}
static int check_stack_access(struct bpf_verifier_env *env,
@@ -2415,7 +2447,7 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
{
struct bpf_reg_state *reg = reg_state(env, regno);
struct bpf_func_state *state = func(env, reg);
- int err, min_off, max_off, i, slot, spi;
+ int err, min_off, max_off, i, j, slot, spi;
if (reg->type != PTR_TO_STACK) {
/* Allow zero-byte read from NULL, regardless of pointer type */
@@ -2503,6 +2535,14 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
*stype = STACK_MISC;
goto mark;
}
+ if (state->stack[spi].slot_type[0] == STACK_SPILL &&
+ state->stack[spi].spilled_ptr.type == SCALAR_VALUE) {
+ __mark_reg_unknown(&state->stack[spi].spilled_ptr);
+ for (j = 0; j < BPF_REG_SIZE; j++)
+ state->stack[spi].slot_type[j] = STACK_MISC;
+ goto mark;
+ }
+
err:
if (tnum_is_const(reg->var_off)) {
verbose(env, "invalid indirect read from stack off %d+%d size %d\n",
generated by cgit v1.2.3-55-g7522 (git 2.39.0) at 2024-06-02 20:49:20 +0200