bpf: verifier: Refactor helper access type tracking

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.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/ff885c0e5859e0cd12077c3148ff0754cad4f7ed.1736886479.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

12 files changed, 26 insertions, 25 deletions

diff --git a/tools/testing/selftests/bpf/progs/dynptr_fail.c b/tools/testing/selftests/bpf/progs/dynptr_fail.c
index dfd817d0348c4..bd8f15229f5c7 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_fail.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_fail.c
@@ -192,7 +192,7 @@ done:
 
 /* 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 5da001ca57a5f..09d027bd3ea80 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 8a403470e557f..046a204c8fc69 100644
--- a/tools/testing/selftests/bpf/progs/uninit_stack.c
+++ b/tools/testing/selftests/bpf/progs/uninit_stack.c
@@ -70,7 +70,8 @@ __naked int helper_uninit_to_misc(void *ctx)
 		r1 = r10;				\
 		r1 += -128;				\
 		r2 = 32;				\
-		call %[bpf_trace_printk];		\
+		r3 = 0;					\
+		call %[bpf_probe_read_user];		\
 		/* Call to dummy() forces print_verifier_state(..., true),	\
 		 * thus showing the stack state, matched by __msg().		\
 		 */					\
@@ -79,7 +80,7 @@ __naked int helper_uninit_to_misc(void *ctx)
 		exit;					\
 "
 		      :
-		      : __imm(bpf_trace_printk),
+		      : __imm(bpf_probe_read_user),
 			__imm(dummy)
 		      : __clobber_all);
 }
diff --git a/tools/testing/selftests/bpf/progs/verifier_basic_stack.c b/tools/testing/selftests/bpf/progs/verifier_basic_stack.c
index 8d77cc5323d33..fb62e09f21146 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 ba8922b2eebd9..68c568c3c3a01 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 50c6b22606f69..f2c54e4d89ebe 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 5f2efb895edbb..59e34d5586543 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 4ccf1ebc42d16..256956ea1ac51 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 7cc83acac7271..c689665e07b97 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 7ea535bfbacd3..a4a5e20716040 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 c810f4f6f479c..1d36d01b746e7 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 7afc2619ab146..18596ae0b0c19 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,