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Merge pull request #325 from zandrey/5.4-2.3.x-imx
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Update 5.4-2.3.x-imx up to v5.4.116
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@otavio
otavio authored May 2, 2021
2 parents 28910e0 + 2f748db commit 3431b95
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Showing 6 changed files with 174 additions and 103 deletions.
2 changes: 1 addition & 1 deletion Makefile
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
VERSION = 5
PATCHLEVEL = 4
SUBLEVEL = 115
SUBLEVEL = 116
EXTRAVERSION =
NAME = Kleptomaniac Octopus

Expand Down
233 changes: 159 additions & 74 deletions kernel/bpf/verifier.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4263,40 +4263,51 @@ static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env)
return &env->insn_aux_data[env->insn_idx];
}

enum {
REASON_BOUNDS = -1,
REASON_TYPE = -2,
REASON_PATHS = -3,
REASON_LIMIT = -4,
REASON_STACK = -5,
};

static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg,
u32 *ptr_limit, u8 opcode, bool off_is_neg)
const struct bpf_reg_state *off_reg,
u32 *alu_limit, u8 opcode)
{
bool off_is_neg = off_reg->smin_value < 0;
bool mask_to_left = (opcode == BPF_ADD && off_is_neg) ||
(opcode == BPF_SUB && !off_is_neg);
u32 off, max;
u32 max = 0, ptr_limit = 0;

if (!tnum_is_const(off_reg->var_off) &&
(off_reg->smin_value < 0) != (off_reg->smax_value < 0))
return REASON_BOUNDS;

switch (ptr_reg->type) {
case PTR_TO_STACK:
/* Offset 0 is out-of-bounds, but acceptable start for the
* left direction, see BPF_REG_FP.
* left direction, see BPF_REG_FP. Also, unknown scalar
* offset where we would need to deal with min/max bounds is
* currently prohibited for unprivileged.
*/
max = MAX_BPF_STACK + mask_to_left;
/* Indirect variable offset stack access is prohibited in
* unprivileged mode so it's not handled here.
*/
off = ptr_reg->off + ptr_reg->var_off.value;
if (mask_to_left)
*ptr_limit = MAX_BPF_STACK + off;
else
*ptr_limit = -off - 1;
return *ptr_limit >= max ? -ERANGE : 0;
ptr_limit = -(ptr_reg->var_off.value + ptr_reg->off);
break;
case PTR_TO_MAP_VALUE:
max = ptr_reg->map_ptr->value_size;
if (mask_to_left) {
*ptr_limit = ptr_reg->umax_value + ptr_reg->off;
} else {
off = ptr_reg->smin_value + ptr_reg->off;
*ptr_limit = ptr_reg->map_ptr->value_size - off - 1;
}
return *ptr_limit >= max ? -ERANGE : 0;
ptr_limit = (mask_to_left ?
ptr_reg->smin_value :
ptr_reg->umax_value) + ptr_reg->off;
break;
default:
return -EINVAL;
return REASON_TYPE;
}

if (ptr_limit >= max)
return REASON_LIMIT;
*alu_limit = ptr_limit;
return 0;
}

static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env,
Expand All @@ -4314,7 +4325,7 @@ static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux,
if (aux->alu_state &&
(aux->alu_state != alu_state ||
aux->alu_limit != alu_limit))
return -EACCES;
return REASON_PATHS;

/* Corresponding fixup done in fixup_bpf_calls(). */
aux->alu_state = alu_state;
Expand All @@ -4333,14 +4344,22 @@ static int sanitize_val_alu(struct bpf_verifier_env *env,
return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
}

static bool sanitize_needed(u8 opcode)
{
return opcode == BPF_ADD || opcode == BPF_SUB;
}

static int sanitize_ptr_alu(struct bpf_verifier_env *env,
struct bpf_insn *insn,
const struct bpf_reg_state *ptr_reg,
const struct bpf_reg_state *off_reg,
struct bpf_reg_state *dst_reg,
bool off_is_neg)
struct bpf_insn_aux_data *tmp_aux,
const bool commit_window)
{
struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : tmp_aux;
struct bpf_verifier_state *vstate = env->cur_state;
struct bpf_insn_aux_data *aux = cur_aux(env);
bool off_is_neg = off_reg->smin_value < 0;
bool ptr_is_dst_reg = ptr_reg == dst_reg;
u8 opcode = BPF_OP(insn->code);
u32 alu_state, alu_limit;
Expand All @@ -4358,18 +4377,33 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env,
if (vstate->speculative)
goto do_sim;

alu_state = off_is_neg ? BPF_ALU_NEG_VALUE : 0;
alu_state |= ptr_is_dst_reg ?
BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;

err = retrieve_ptr_limit(ptr_reg, &alu_limit, opcode, off_is_neg);
err = retrieve_ptr_limit(ptr_reg, off_reg, &alu_limit, opcode);
if (err < 0)
return err;

if (commit_window) {
/* In commit phase we narrow the masking window based on
* the observed pointer move after the simulated operation.
*/
alu_state = tmp_aux->alu_state;
alu_limit = abs(tmp_aux->alu_limit - alu_limit);
} else {
alu_state = off_is_neg ? BPF_ALU_NEG_VALUE : 0;
alu_state |= ptr_is_dst_reg ?
BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;
}

err = update_alu_sanitation_state(aux, alu_state, alu_limit);
if (err < 0)
return err;
do_sim:
/* If we're in commit phase, we're done here given we already
* pushed the truncated dst_reg into the speculative verification
* stack.
*/
if (commit_window)
return 0;

/* Simulate and find potential out-of-bounds access under
* speculative execution from truncation as a result of
* masking when off was not within expected range. If off
Expand All @@ -4386,7 +4420,81 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env,
ret = push_stack(env, env->insn_idx + 1, env->insn_idx, true);
if (!ptr_is_dst_reg && ret)
*dst_reg = tmp;
return !ret ? -EFAULT : 0;
return !ret ? REASON_STACK : 0;
}

static int sanitize_err(struct bpf_verifier_env *env,
const struct bpf_insn *insn, int reason,
const struct bpf_reg_state *off_reg,
const struct bpf_reg_state *dst_reg)
{
static const char *err = "pointer arithmetic with it prohibited for !root";
const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub";
u32 dst = insn->dst_reg, src = insn->src_reg;

switch (reason) {
case REASON_BOUNDS:
verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n",
off_reg == dst_reg ? dst : src, err);
break;
case REASON_TYPE:
verbose(env, "R%d has pointer with unsupported alu operation, %s\n",
off_reg == dst_reg ? src : dst, err);
break;
case REASON_PATHS:
verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n",
dst, op, err);
break;
case REASON_LIMIT:
verbose(env, "R%d tried to %s beyond pointer bounds, %s\n",
dst, op, err);
break;
case REASON_STACK:
verbose(env, "R%d could not be pushed for speculative verification, %s\n",
dst, err);
break;
default:
verbose(env, "verifier internal error: unknown reason (%d)\n",
reason);
break;
}

return -EACCES;
}

static int sanitize_check_bounds(struct bpf_verifier_env *env,
const struct bpf_insn *insn,
const struct bpf_reg_state *dst_reg)
{
u32 dst = insn->dst_reg;

/* For unprivileged we require that resulting offset must be in bounds
* in order to be able to sanitize access later on.
*/
if (env->allow_ptr_leaks)
return 0;

switch (dst_reg->type) {
case PTR_TO_STACK:
if (check_stack_access(env, dst_reg, dst_reg->off +
dst_reg->var_off.value, 1)) {
verbose(env, "R%d stack pointer arithmetic goes out of range, "
"prohibited for !root\n", dst);
return -EACCES;
}
break;
case PTR_TO_MAP_VALUE:
if (check_map_access(env, dst, dst_reg->off, 1, false)) {
verbose(env, "R%d pointer arithmetic of map value goes out of range, "
"prohibited for !root\n", dst);
return -EACCES;
}
break;
default:
break;
}

return 0;
}

/* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
Expand All @@ -4407,8 +4515,9 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value;
u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value,
umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value;
u32 dst = insn->dst_reg, src = insn->src_reg;
struct bpf_insn_aux_data tmp_aux = {};
u8 opcode = BPF_OP(insn->code);
u32 dst = insn->dst_reg;
int ret;

dst_reg = &regs[dst];
Expand Down Expand Up @@ -4451,13 +4560,6 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
verbose(env, "R%d pointer arithmetic on %s prohibited\n",
dst, reg_type_str[ptr_reg->type]);
return -EACCES;
case PTR_TO_MAP_VALUE:
if (!env->allow_ptr_leaks && !known && (smin_val < 0) != (smax_val < 0)) {
verbose(env, "R%d has unknown scalar with mixed signed bounds, pointer arithmetic with it prohibited for !root\n",
off_reg == dst_reg ? dst : src);
return -EACCES;
}
/* fall-through */
default:
break;
}
Expand All @@ -4472,13 +4574,15 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
!check_reg_sane_offset(env, ptr_reg, ptr_reg->type))
return -EINVAL;

if (sanitize_needed(opcode)) {
ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg,
&tmp_aux, false);
if (ret < 0)
return sanitize_err(env, insn, ret, off_reg, dst_reg);
}

switch (opcode) {
case BPF_ADD:
ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0);
if (ret < 0) {
verbose(env, "R%d tried to add from different maps, paths, or prohibited types\n", dst);
return ret;
}
/* We can take a fixed offset as long as it doesn't overflow
* the s32 'off' field
*/
Expand Down Expand Up @@ -4529,11 +4633,6 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
}
break;
case BPF_SUB:
ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0);
if (ret < 0) {
verbose(env, "R%d tried to sub from different maps, paths, or prohibited types\n", dst);
return ret;
}
if (dst_reg == off_reg) {
/* scalar -= pointer. Creates an unknown scalar */
verbose(env, "R%d tried to subtract pointer from scalar\n",
Expand Down Expand Up @@ -4614,22 +4713,13 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
__reg_deduce_bounds(dst_reg);
__reg_bound_offset(dst_reg);

/* For unprivileged we require that resulting offset must be in bounds
* in order to be able to sanitize access later on.
*/
if (!env->allow_ptr_leaks) {
if (dst_reg->type == PTR_TO_MAP_VALUE &&
check_map_access(env, dst, dst_reg->off, 1, false)) {
verbose(env, "R%d pointer arithmetic of map value goes out of range, "
"prohibited for !root\n", dst);
return -EACCES;
} else if (dst_reg->type == PTR_TO_STACK &&
check_stack_access(env, dst_reg, dst_reg->off +
dst_reg->var_off.value, 1)) {
verbose(env, "R%d stack pointer arithmetic goes out of range, "
"prohibited for !root\n", dst);
return -EACCES;
}
if (sanitize_check_bounds(env, insn, dst_reg) < 0)
return -EACCES;
if (sanitize_needed(opcode)) {
ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg,
&tmp_aux, true);
if (ret < 0)
return sanitize_err(env, insn, ret, off_reg, dst_reg);
}

return 0;
Expand All @@ -4650,7 +4740,6 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
s64 smin_val, smax_val;
u64 umin_val, umax_val;
u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32;
u32 dst = insn->dst_reg;
int ret;

if (insn_bitness == 32) {
Expand Down Expand Up @@ -4684,13 +4773,14 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
return 0;
}

if (sanitize_needed(opcode)) {
ret = sanitize_val_alu(env, insn);
if (ret < 0)
return sanitize_err(env, insn, ret, NULL, NULL);
}

switch (opcode) {
case BPF_ADD:
ret = sanitize_val_alu(env, insn);
if (ret < 0) {
verbose(env, "R%d tried to add from different pointers or scalars\n", dst);
return ret;
}
if (signed_add_overflows(dst_reg->smin_value, smin_val) ||
signed_add_overflows(dst_reg->smax_value, smax_val)) {
dst_reg->smin_value = S64_MIN;
Expand All @@ -4710,11 +4800,6 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
break;
case BPF_SUB:
ret = sanitize_val_alu(env, insn);
if (ret < 0) {
verbose(env, "R%d tried to sub from different pointers or scalars\n", dst);
return ret;
}
if (signed_sub_overflows(dst_reg->smin_value, smax_val) ||
signed_sub_overflows(dst_reg->smax_value, smin_val)) {
/* Overflow possible, we know nothing */
Expand Down
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