bpf: Rename MEM_ALLOC to MEM_RINGBUF

Currently, verifier uses MEM_ALLOC type tag to specially tag memory
returned from bpf_ringbuf_reserve helper. However, this is currently
only used for this purpose and there is an implicit assumption that it
only refers to ringbuf memory (e.g. the check for ARG_PTR_TO_ALLOC_MEM
in check_func_arg_reg_off).

Hence, rename MEM_ALLOC to MEM_RINGBUF to indicate this special
relationship and instead open the use of MEM_ALLOC for more generic
allocations made for user types.

Also, since ARG_PTR_TO_ALLOC_MEM_OR_NULL is unused, simply drop it.

Finally, update selftests using 'alloc_' verifier string to 'ringbuf_'.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221114191547.1694267-7-memxor@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/bpf.h

@@ -488,10 +488,8 @@ enum bpf_type_flag {
 	 */
 	MEM_RDONLY		= BIT(1 + BPF_BASE_TYPE_BITS),
 
-	/* MEM was "allocated" from a different helper, and cannot be mixed
-	 * with regular non-MEM_ALLOC'ed MEM types.
-	 */
-	MEM_ALLOC		= BIT(2 + BPF_BASE_TYPE_BITS),
+	/* MEM points to BPF ring buffer reservation. */
+	MEM_RINGBUF		= BIT(2 + BPF_BASE_TYPE_BITS),
 
 	/* MEM is in user address space. */
 	MEM_USER		= BIT(3 + BPF_BASE_TYPE_BITS),
@@ -565,7 +563,7 @@ enum bpf_arg_type {
 	ARG_PTR_TO_LONG,	/* pointer to long */
 	ARG_PTR_TO_SOCKET,	/* pointer to bpf_sock (fullsock) */
 	ARG_PTR_TO_BTF_ID,	/* pointer to in-kernel struct */
-	ARG_PTR_TO_ALLOC_MEM,	/* pointer to dynamically allocated memory */
+	ARG_PTR_TO_RINGBUF_MEM,	/* pointer to dynamically reserved ringbuf memory */
 	ARG_CONST_ALLOC_SIZE_OR_ZERO,	/* number of allocated bytes requested */
 	ARG_PTR_TO_BTF_ID_SOCK_COMMON,	/* pointer to in-kernel sock_common or bpf-mirrored bpf_sock */
 	ARG_PTR_TO_PERCPU_BTF_ID,	/* pointer to in-kernel percpu type */
@@ -582,7 +580,6 @@ enum bpf_arg_type {
 	ARG_PTR_TO_MEM_OR_NULL		= PTR_MAYBE_NULL | ARG_PTR_TO_MEM,
 	ARG_PTR_TO_CTX_OR_NULL		= PTR_MAYBE_NULL | ARG_PTR_TO_CTX,
 	ARG_PTR_TO_SOCKET_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_SOCKET,
-	ARG_PTR_TO_ALLOC_MEM_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_ALLOC_MEM,
 	ARG_PTR_TO_STACK_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_STACK,
 	ARG_PTR_TO_BTF_ID_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_BTF_ID,
 	/* pointer to memory does not need to be initialized, helper function must fill
@@ -617,7 +614,7 @@ enum bpf_return_type {
 	RET_PTR_TO_SOCKET_OR_NULL	= PTR_MAYBE_NULL | RET_PTR_TO_SOCKET,
 	RET_PTR_TO_TCP_SOCK_OR_NULL	= PTR_MAYBE_NULL | RET_PTR_TO_TCP_SOCK,
 	RET_PTR_TO_SOCK_COMMON_OR_NULL	= PTR_MAYBE_NULL | RET_PTR_TO_SOCK_COMMON,
-	RET_PTR_TO_ALLOC_MEM_OR_NULL	= PTR_MAYBE_NULL | MEM_ALLOC | RET_PTR_TO_MEM,
+	RET_PTR_TO_RINGBUF_MEM_OR_NULL	= PTR_MAYBE_NULL | MEM_RINGBUF | RET_PTR_TO_MEM,
 	RET_PTR_TO_DYNPTR_MEM_OR_NULL	= PTR_MAYBE_NULL | RET_PTR_TO_MEM,
 	RET_PTR_TO_BTF_ID_OR_NULL	= PTR_MAYBE_NULL | RET_PTR_TO_BTF_ID,
 

kernel/bpf/ringbuf.c

@@ -447,7 +447,7 @@ BPF_CALL_3(bpf_ringbuf_reserve, struct bpf_map *, map, u64, size, u64, flags)
 
 const struct bpf_func_proto bpf_ringbuf_reserve_proto = {
 	.func		= bpf_ringbuf_reserve,
-	.ret_type	= RET_PTR_TO_ALLOC_MEM_OR_NULL,
+	.ret_type	= RET_PTR_TO_RINGBUF_MEM_OR_NULL,
 	.arg1_type	= ARG_CONST_MAP_PTR,
 	.arg2_type	= ARG_CONST_ALLOC_SIZE_OR_ZERO,
 	.arg3_type	= ARG_ANYTHING,
@@ -490,7 +490,7 @@ BPF_CALL_2(bpf_ringbuf_submit, void *, sample, u64, flags)
 const struct bpf_func_proto bpf_ringbuf_submit_proto = {
 	.func		= bpf_ringbuf_submit,
 	.ret_type	= RET_VOID,
-	.arg1_type	= ARG_PTR_TO_ALLOC_MEM | OBJ_RELEASE,
+	.arg1_type	= ARG_PTR_TO_RINGBUF_MEM | OBJ_RELEASE,
 	.arg2_type	= ARG_ANYTHING,
 };
 
@@ -503,7 +503,7 @@ BPF_CALL_2(bpf_ringbuf_discard, void *, sample, u64, flags)
 const struct bpf_func_proto bpf_ringbuf_discard_proto = {
 	.func		= bpf_ringbuf_discard,
 	.ret_type	= RET_VOID,
-	.arg1_type	= ARG_PTR_TO_ALLOC_MEM | OBJ_RELEASE,
+	.arg1_type	= ARG_PTR_TO_RINGBUF_MEM | OBJ_RELEASE,
 	.arg2_type	= ARG_ANYTHING,
 };
 

kernel/bpf/verifier.c

@@ -577,8 +577,8 @@ static const char *reg_type_str(struct bpf_verifier_env *env,
 
 	if (type & MEM_RDONLY)
 		strncpy(prefix, "rdonly_", 32);
-	if (type & MEM_ALLOC)
-		strncpy(prefix, "alloc_", 32);
+	if (type & MEM_RINGBUF)
+		strncpy(prefix, "ringbuf_", 32);
 	if (type & MEM_USER)
 		strncpy(prefix, "user_", 32);
 	if (type & MEM_PERCPU)
@@ -5785,7 +5785,7 @@ static const struct bpf_reg_types mem_types = {
 		PTR_TO_MAP_KEY,
 		PTR_TO_MAP_VALUE,
 		PTR_TO_MEM,
-		PTR_TO_MEM | MEM_ALLOC,
+		PTR_TO_MEM | MEM_RINGBUF,
 		PTR_TO_BUF,
 	},
 };
@@ -5803,7 +5803,7 @@ static const struct bpf_reg_types int_ptr_types = {
 static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } };
 static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } };
 static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } };
-static const struct bpf_reg_types alloc_mem_types = { .types = { PTR_TO_MEM | MEM_ALLOC } };
+static const struct bpf_reg_types ringbuf_mem_types = { .types = { PTR_TO_MEM | MEM_RINGBUF } };
 static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } };
 static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID } };
 static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } };
@@ -5836,7 +5836,7 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
 	[ARG_PTR_TO_BTF_ID]		= &btf_ptr_types,
 	[ARG_PTR_TO_SPIN_LOCK]		= &spin_lock_types,
 	[ARG_PTR_TO_MEM]		= &mem_types,
-	[ARG_PTR_TO_ALLOC_MEM]		= &alloc_mem_types,
+	[ARG_PTR_TO_RINGBUF_MEM]	= &ringbuf_mem_types,
 	[ARG_PTR_TO_INT]		= &int_ptr_types,
 	[ARG_PTR_TO_LONG]		= &int_ptr_types,
 	[ARG_PTR_TO_PERCPU_BTF_ID]	= &percpu_btf_ptr_types,
@@ -5957,14 +5957,14 @@ int check_func_arg_reg_off(struct bpf_verifier_env *env,
 	case PTR_TO_MAP_VALUE:
 	case PTR_TO_MEM:
 	case PTR_TO_MEM | MEM_RDONLY:
-	case PTR_TO_MEM | MEM_ALLOC:
+	case PTR_TO_MEM | MEM_RINGBUF:
 	case PTR_TO_BUF:
 	case PTR_TO_BUF | MEM_RDONLY:
 	case SCALAR_VALUE:
 		/* Some of the argument types nevertheless require a
 		 * zero register offset.
 		 */
-		if (base_type(arg_type) != ARG_PTR_TO_ALLOC_MEM)
+		if (base_type(arg_type) != ARG_PTR_TO_RINGBUF_MEM)
 			return 0;
 		break;
 	/* All the rest must be rejected, except PTR_TO_BTF_ID which allows

tools/testing/selftests/bpf/prog_tests/dynptr.c

@@ -17,7 +17,7 @@ static struct {
 	{"ringbuf_missing_release2", "Unreleased reference id=2"},
 	{"ringbuf_missing_release_callback", "Unreleased reference id"},
 	{"use_after_invalid", "Expected an initialized dynptr as arg #3"},
-	{"ringbuf_invalid_api", "type=mem expected=alloc_mem"},
+	{"ringbuf_invalid_api", "type=mem expected=ringbuf_mem"},
 	{"add_dynptr_to_map1", "invalid indirect read from stack"},
 	{"add_dynptr_to_map2", "invalid indirect read from stack"},
 	{"data_slice_out_of_bounds_ringbuf", "value is outside of the allowed memory range"},

tools/testing/selftests/bpf/verifier/ringbuf.c

@@ -28,7 +28,7 @@
 	},
 	.fixup_map_ringbuf = { 1 },
 	.result = REJECT,
-	.errstr = "dereference of modified alloc_mem ptr R1",
+	.errstr = "dereference of modified ringbuf_mem ptr R1",
 },
 {
 	"ringbuf: invalid reservation offset 2",

tools/testing/selftests/bpf/verifier/spill_fill.c

@@ -84,7 +84,7 @@
 	},
 	.fixup_map_ringbuf = { 1 },
 	.result = REJECT,
-	.errstr = "R0 pointer arithmetic on alloc_mem_or_null prohibited",
+	.errstr = "R0 pointer arithmetic on ringbuf_mem_or_null prohibited",
 },
 {
 	"check corrupted spill/fill",