Previously, the verifier was treating all PTR_TO_STACK registers passed
to a helper call as potentially written to by the helper. However, all
calls to check_stack_range_initialized() already have precise access type
information available.
Rather than treat ACCESS_HELPER as a proxy for BPF_WRITE, pass
enum bpf_access_type to check_stack_range_initialized() to more
precisely track helper arguments.
One benefit from this precision is that registers tracked as valid
spills and passed as a read-only helper argument remain tracked after
the call. Rather than being marked STACK_MISC afterwards.
An additional benefit is the verifier logs are also more precise. For
this particular error, users will enjoy a slightly clearer message. See
included selftest updates for examples.
Signed-off-by: Daniel Xu <dxu@xxxxxxxxx>
---
kernel/bpf/verifier.c | 45 +++++++------------
.../testing/selftests/bpf/progs/dynptr_fail.c | 6 +--
.../selftests/bpf/progs/test_global_func10.c | 2 +-
.../selftests/bpf/progs/uninit_stack.c | 29 ------------
.../bpf/progs/verifier_basic_stack.c | 2 +-
.../selftests/bpf/progs/verifier_const_or.c | 4 +-
.../progs/verifier_helper_access_var_len.c | 12 ++---
.../selftests/bpf/progs/verifier_int_ptr.c | 2 +-
.../selftests/bpf/progs/verifier_mtu.c | 2 +-
.../selftests/bpf/progs/verifier_raw_stack.c | 4 +-
.../selftests/bpf/progs/verifier_unpriv.c | 2 +-
.../selftests/bpf/progs/verifier_var_off.c | 8 ++--
tools/testing/selftests/bpf/verifier/calls.c | 2 +-
13 files changed, 39 insertions(+), 81 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 630150013479..58b36cc96bd5 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5302,7 +5302,7 @@ enum bpf_access_src {
static int check_stack_range_initialized(struct bpf_verifier_env *env,
int regno, int off, int access_size,
bool zero_size_allowed,
- enum bpf_access_src type,
+ enum bpf_access_type type,
struct bpf_call_arg_meta *meta);
static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno)
@@ -5335,7 +5335,7 @@ static int check_stack_read_var_off(struct bpf_verifier_env *env,
/* Note that we pass a NULL meta, so raw access will not be permitted.
*/
err = check_stack_range_initialized(env, ptr_regno, off, size,
- false, ACCESS_DIRECT, NULL);
+ false, BPF_READ, NULL);
if (err)
return err;
@@ -7205,7 +7205,7 @@ static int check_stack_slot_within_bounds(struct bpf_verifier_env *env,
static int check_stack_access_within_bounds(
struct bpf_verifier_env *env,
int regno, int off, int access_size,
- enum bpf_access_src src, enum bpf_access_type type)
+ enum bpf_access_type type)
{
struct bpf_reg_state *regs = cur_regs(env);
struct bpf_reg_state *reg = regs + regno;
@@ -7214,10 +7214,7 @@ static int check_stack_access_within_bounds(
int err;
char *err_extra;
- if (src == ACCESS_HELPER)
- /* We don't know if helpers are reading or writing (or both). */
- err_extra = " indirect access to";
- else if (type == BPF_READ)
+ if (type == BPF_READ)
err_extra = " read from";
else
err_extra = " write to";
@@ -7435,7 +7432,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
} else if (reg->type == PTR_TO_STACK) {
/* Basic bounds checks. */
- err = check_stack_access_within_bounds(env, regno, off, size, ACCESS_DIRECT, t);
+ err = check_stack_access_within_bounds(env, regno, off, size, t);
if (err)
return err;
@@ -7655,13 +7652,11 @@ static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_i
static int check_stack_range_initialized(
struct bpf_verifier_env *env, int regno, int off,
int access_size, bool zero_size_allowed,
- enum bpf_access_src type, struct bpf_call_arg_meta *meta)
+ enum bpf_access_type type, struct bpf_call_arg_meta *meta)
{
struct bpf_reg_state *reg = reg_state(env, regno);
struct bpf_func_state *state = func(env, reg);
int err, min_off, max_off, i, j, slot, spi;
- char *err_extra = type == ACCESS_HELPER ? " indirect" : "";
- enum bpf_access_type bounds_check_type;
/* Some accesses can write anything into the stack, others are
* read-only.
*/
@@ -7672,18 +7667,10 @@ static int check_stack_range_initialized(
return -EACCES;
}
- if (type == ACCESS_HELPER) {
- /* The bounds checks for writes are more permissive than for
- * reads. However, if raw_mode is not set, we'll do extra
- * checks below.
- */
- bounds_check_type = BPF_WRITE;
+ if (type == BPF_WRITE)
clobber = true;
- } else {
- bounds_check_type = BPF_READ;
- }
- err = check_stack_access_within_bounds(env, regno, off, access_size,
- type, bounds_check_type);
+
+ err = check_stack_access_within_bounds(env, regno, off, access_size, type);
if (err)
return err;
@@ -7700,8 +7687,8 @@ static int check_stack_range_initialized(
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, "R%d%s variable offset stack access prohibited for !root, var_off=%s\n",
- regno, err_extra, tn_buf);
+ verbose(env, "R%d variable offset stack access prohibited for !root, var_off=%s\n",
+ regno, tn_buf);
return -EACCES;
}
/* Only initialized buffer on stack is allowed to be accessed
@@ -7782,14 +7769,14 @@ static int check_stack_range_initialized(
}
if (tnum_is_const(reg->var_off)) {
- verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n",
- err_extra, regno, min_off, i - min_off, access_size);
+ verbose(env, "invalid read from stack R%d off %d+%d size %d\n",
+ regno, min_off, i - min_off, access_size);
} else {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, "invalid%s read from stack R%d var_off %s+%d size %d\n",
- err_extra, regno, tn_buf, i - min_off, access_size);
+ verbose(env, "invalid read from stack R%d var_off %s+%d size %d\n",
+ regno, tn_buf, i - min_off, access_size);
}
return -EACCES;
mark:
@@ -7864,7 +7851,7 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
return check_stack_range_initialized(
env,
regno, reg->off, access_size,
- zero_size_allowed, ACCESS_HELPER, meta);
+ zero_size_allowed, access_type, meta);
case PTR_TO_BTF_ID:
return check_ptr_to_btf_access(env, regs, regno, reg->off,
access_size, BPF_READ, -1);
diff --git a/tools/testing/selftests/bpf/progs/dynptr_fail.c b/tools/testing/selftests/bpf/progs/dynptr_fail.c
index dfd817d0348c..bd8f15229f5c 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_fail.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_fail.c
@@ -192,7 +192,7 @@ int ringbuf_invalid_api(void *ctx)
/* Can't add a dynptr to a map */
SEC("?raw_tp")
-__failure __msg("invalid indirect read from stack")
+__failure __msg("invalid read from stack")
int add_dynptr_to_map1(void *ctx)
{
struct bpf_dynptr ptr;
@@ -210,7 +210,7 @@ int add_dynptr_to_map1(void *ctx)
/* Can't add a struct with an embedded dynptr to a map */
SEC("?raw_tp")
-__failure __msg("invalid indirect read from stack")
+__failure __msg("invalid read from stack")
int add_dynptr_to_map2(void *ctx)
{
struct test_info x;
@@ -398,7 +398,7 @@ int data_slice_missing_null_check2(void *ctx)
* dynptr argument
*/
SEC("?raw_tp")
-__failure __msg("invalid indirect read from stack")
+__failure __msg("invalid read from stack")
int invalid_helper1(void *ctx)
{
struct bpf_dynptr ptr;
diff --git a/tools/testing/selftests/bpf/progs/test_global_func10.c b/tools/testing/selftests/bpf/progs/test_global_func10.c
index 5da001ca57a5..09d027bd3ea8 100644
--- a/tools/testing/selftests/bpf/progs/test_global_func10.c
+++ b/tools/testing/selftests/bpf/progs/test_global_func10.c
@@ -26,7 +26,7 @@ __noinline int foo(const struct Big *big)
}
SEC("cgroup_skb/ingress")
-__failure __msg("invalid indirect access to stack")
+__failure __msg("invalid read from stack")
int global_func10(struct __sk_buff *skb)
{
const struct Small small = {.x = skb->len };
diff --git a/tools/testing/selftests/bpf/progs/uninit_stack.c b/tools/testing/selftests/bpf/progs/uninit_stack.c
index 8a403470e557..87a2f8f7e92a 100644
--- a/tools/testing/selftests/bpf/progs/uninit_stack.c
+++ b/tools/testing/selftests/bpf/progs/uninit_stack.c
@@ -55,33 +55,4 @@ exit_%=: r0 = 0; \
: __clobber_all);
}
-static __noinline void dummy(void) {}
-
-/* Pass a pointer to uninitialized stack memory to a helper.
- * Passed memory block should be marked as STACK_MISC after helper call.
- */
-SEC("socket")
-__log_level(7) __msg("fp-104=mmmmmmmm")
-__naked int helper_uninit_to_misc(void *ctx)
-{
- asm volatile (" \
- /* force stack depth to be 128 */ \
- *(u64*)(r10 - 128) = r1; \
- r1 = r10; \
- r1 += -128; \
- r2 = 32; \
- call %[bpf_trace_printk]; \
- /* Call to dummy() forces print_verifier_state(..., true), \
- * thus showing the stack state, matched by __msg(). \
- */ \
- call %[dummy]; \
- r0 = 0; \
- exit; \
-"
- :
- : __imm(bpf_trace_printk),
- __imm(dummy)
- : __clobber_all);
-}
-
char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/verifier_basic_stack.c b/tools/testing/selftests/bpf/progs/verifier_basic_stack.c
index 8d77cc5323d3..fb62e09f2114 100644
--- a/tools/testing/selftests/bpf/progs/verifier_basic_stack.c
+++ b/tools/testing/selftests/bpf/progs/verifier_basic_stack.c
@@ -28,7 +28,7 @@ __naked void stack_out_of_bounds(void)
SEC("socket")
__description("uninitialized stack1")
__success __log_level(4) __msg("stack depth 8")
-__failure_unpriv __msg_unpriv("invalid indirect read from stack")
+__failure_unpriv __msg_unpriv("invalid read from stack")
__naked void uninitialized_stack1(void)
{
asm volatile (" \
diff --git a/tools/testing/selftests/bpf/progs/verifier_const_or.c b/tools/testing/selftests/bpf/progs/verifier_const_or.c
index ba8922b2eebd..68c568c3c3a0 100644
--- a/tools/testing/selftests/bpf/progs/verifier_const_or.c
+++ b/tools/testing/selftests/bpf/progs/verifier_const_or.c
@@ -25,7 +25,7 @@ __naked void constant_should_keep_constant_type(void)
SEC("tracepoint")
__description("constant register |= constant should not bypass stack boundary checks")
-__failure __msg("invalid indirect access to stack R1 off=-48 size=58")
+__failure __msg("invalid write to stack R1 off=-48 size=58")
__naked void not_bypass_stack_boundary_checks_1(void)
{
asm volatile (" \
@@ -62,7 +62,7 @@ __naked void register_should_keep_constant_type(void)
SEC("tracepoint")
__description("constant register |= constant register should not bypass stack boundary checks")
-__failure __msg("invalid indirect access to stack R1 off=-48 size=58")
+__failure __msg("invalid write to stack R1 off=-48 size=58")
__naked void not_bypass_stack_boundary_checks_2(void)
{
asm volatile (" \
diff --git a/tools/testing/selftests/bpf/progs/verifier_helper_access_var_len.c b/tools/testing/selftests/bpf/progs/verifier_helper_access_var_len.c
index 50c6b22606f6..f2c54e4d89eb 100644
--- a/tools/testing/selftests/bpf/progs/verifier_helper_access_var_len.c
+++ b/tools/testing/selftests/bpf/progs/verifier_helper_access_var_len.c
@@ -67,7 +67,7 @@ SEC("socket")
__description("helper access to variable memory: stack, bitwise AND, zero included")
/* in privileged mode reads from uninitialized stack locations are permitted */
__success __failure_unpriv
-__msg_unpriv("invalid indirect read from stack R2 off -64+0 size 64")
+__msg_unpriv("invalid read from stack R2 off -64+0 size 64")
__retval(0)
__naked void stack_bitwise_and_zero_included(void)
{
@@ -100,7 +100,7 @@ __naked void stack_bitwise_and_zero_included(void)
SEC("tracepoint")
__description("helper access to variable memory: stack, bitwise AND + JMP, wrong max")
-__failure __msg("invalid indirect access to stack R1 off=-64 size=65")
+__failure __msg("invalid write to stack R1 off=-64 size=65")
__naked void bitwise_and_jmp_wrong_max(void)
{
asm volatile (" \
@@ -187,7 +187,7 @@ l0_%=: r0 = 0; \
SEC("tracepoint")
__description("helper access to variable memory: stack, JMP, bounds + offset")
-__failure __msg("invalid indirect access to stack R1 off=-64 size=65")
+__failure __msg("invalid write to stack R1 off=-64 size=65")
__naked void memory_stack_jmp_bounds_offset(void)
{
asm volatile (" \
@@ -211,7 +211,7 @@ l0_%=: r0 = 0; \
SEC("tracepoint")
__description("helper access to variable memory: stack, JMP, wrong max")
-__failure __msg("invalid indirect access to stack R1 off=-64 size=65")
+__failure __msg("invalid write to stack R1 off=-64 size=65")
__naked void memory_stack_jmp_wrong_max(void)
{
asm volatile (" \
@@ -260,7 +260,7 @@ SEC("socket")
__description("helper access to variable memory: stack, JMP, no min check")
/* in privileged mode reads from uninitialized stack locations are permitted */
__success __failure_unpriv
-__msg_unpriv("invalid indirect read from stack R2 off -64+0 size 64")
+__msg_unpriv("invalid read from stack R2 off -64+0 size 64")
__retval(0)
__naked void stack_jmp_no_min_check(void)
{
@@ -750,7 +750,7 @@ SEC("socket")
__description("helper access to variable memory: 8 bytes leak")
/* in privileged mode reads from uninitialized stack locations are permitted */
__success __failure_unpriv
-__msg_unpriv("invalid indirect read from stack R2 off -64+32 size 64")
+__msg_unpriv("invalid read from stack R2 off -64+32 size 64")
__retval(0)
__naked void variable_memory_8_bytes_leak(void)
{
diff --git a/tools/testing/selftests/bpf/progs/verifier_int_ptr.c b/tools/testing/selftests/bpf/progs/verifier_int_ptr.c
index 5f2efb895edb..59e34d558654 100644
--- a/tools/testing/selftests/bpf/progs/verifier_int_ptr.c
+++ b/tools/testing/selftests/bpf/progs/verifier_int_ptr.c
@@ -96,7 +96,7 @@ __naked void arg_ptr_to_long_misaligned(void)
SEC("cgroup/sysctl")
__description("arg pointer to long size < sizeof(long)")
-__failure __msg("invalid indirect access to stack R4 off=-4 size=8")
+__failure __msg("invalid write to stack R4 off=-4 size=8")
__naked void to_long_size_sizeof_long(void)
{
asm volatile (" \
diff --git a/tools/testing/selftests/bpf/progs/verifier_mtu.c b/tools/testing/selftests/bpf/progs/verifier_mtu.c
index 4ccf1ebc42d1..256956ea1ac5 100644
--- a/tools/testing/selftests/bpf/progs/verifier_mtu.c
+++ b/tools/testing/selftests/bpf/progs/verifier_mtu.c
@@ -8,7 +8,7 @@ SEC("tc/ingress")
__description("uninit/mtu: write rejected")
__success
__caps_unpriv(CAP_BPF|CAP_NET_ADMIN)
-__failure_unpriv __msg_unpriv("invalid indirect read from stack")
+__failure_unpriv __msg_unpriv("invalid read from stack")
int tc_uninit_mtu(struct __sk_buff *ctx)
{
__u32 mtu;
diff --git a/tools/testing/selftests/bpf/progs/verifier_raw_stack.c b/tools/testing/selftests/bpf/progs/verifier_raw_stack.c
index 7cc83acac727..c689665e07b9 100644
--- a/tools/testing/selftests/bpf/progs/verifier_raw_stack.c
+++ b/tools/testing/selftests/bpf/progs/verifier_raw_stack.c
@@ -236,7 +236,7 @@ __naked void load_bytes_spilled_regs_data(void)
SEC("tc")
__description("raw_stack: skb_load_bytes, invalid access 1")
-__failure __msg("invalid indirect access to stack R3 off=-513 size=8")
+__failure __msg("invalid write to stack R3 off=-513 size=8")
__naked void load_bytes_invalid_access_1(void)
{
asm volatile (" \
@@ -255,7 +255,7 @@ __naked void load_bytes_invalid_access_1(void)
SEC("tc")
__description("raw_stack: skb_load_bytes, invalid access 2")
-__failure __msg("invalid indirect access to stack R3 off=-1 size=8")
+__failure __msg("invalid write to stack R3 off=-1 size=8")
__naked void load_bytes_invalid_access_2(void)
{
asm volatile (" \
diff --git a/tools/testing/selftests/bpf/progs/verifier_unpriv.c b/tools/testing/selftests/bpf/progs/verifier_unpriv.c
index 7ea535bfbacd..a4a5e2071604 100644
--- a/tools/testing/selftests/bpf/progs/verifier_unpriv.c
+++ b/tools/testing/selftests/bpf/progs/verifier_unpriv.c
@@ -199,7 +199,7 @@ __naked void pass_pointer_to_helper_function(void)
SEC("socket")
__description("unpriv: indirectly pass pointer on stack to helper function")
__success __failure_unpriv
-__msg_unpriv("invalid indirect read from stack R2 off -8+0 size 8")
+__msg_unpriv("invalid read from stack R2 off -8+0 size 8")
__retval(0)
__naked void on_stack_to_helper_function(void)
{
diff --git a/tools/testing/selftests/bpf/progs/verifier_var_off.c b/tools/testing/selftests/bpf/progs/verifier_var_off.c
index c810f4f6f479..1d36d01b746e 100644
--- a/tools/testing/selftests/bpf/progs/verifier_var_off.c
+++ b/tools/testing/selftests/bpf/progs/verifier_var_off.c
@@ -203,7 +203,7 @@ __naked void stack_write_clobbers_spilled_regs(void)
SEC("sockops")
__description("indirect variable-offset stack access, unbounded")
-__failure __msg("invalid unbounded variable-offset indirect access to stack R4")
+__failure __msg("invalid unbounded variable-offset write to stack R4")
__naked void variable_offset_stack_access_unbounded(void)
{
asm volatile (" \
@@ -236,7 +236,7 @@ l0_%=: r0 = 0; \
SEC("lwt_in")
__description("indirect variable-offset stack access, max out of bound")
-__failure __msg("invalid variable-offset indirect access to stack R2")
+__failure __msg("invalid variable-offset read from stack R2")
__naked void access_max_out_of_bound(void)
{
asm volatile (" \
@@ -269,7 +269,7 @@ __naked void access_max_out_of_bound(void)
*/
SEC("socket")
__description("indirect variable-offset stack access, zero-sized, max out of bound")
-__failure __msg("invalid variable-offset indirect access to stack R1")
+__failure __msg("invalid variable-offset write to stack R1")
__naked void zero_sized_access_max_out_of_bound(void)
{
asm volatile (" \
@@ -294,7 +294,7 @@ __naked void zero_sized_access_max_out_of_bound(void)
SEC("lwt_in")
__description("indirect variable-offset stack access, min out of bound")
-__failure __msg("invalid variable-offset indirect access to stack R2")
+__failure __msg("invalid variable-offset read from stack R2")
__naked void access_min_out_of_bound(void)
{
asm volatile (" \
diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c
index 7afc2619ab14..18596ae0b0c1 100644
--- a/tools/testing/selftests/bpf/verifier/calls.c
+++ b/tools/testing/selftests/bpf/verifier/calls.c
@@ -2252,7 +2252,7 @@
BPF_EXIT_INSN(),
},
.fixup_map_hash_48b = { 7 },
- .errstr_unpriv = "invalid indirect read from stack R2 off -8+0 size 8",
+ .errstr_unpriv = "invalid read from stack R2 off -8+0 size 8",
.result_unpriv = REJECT,
/* in privileged mode reads from uninitialized stack locations are permitted */
.result = ACCEPT,
--
2.46.0
