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From foo@baz Thu Feb 17 08:07:01 PM CET 2022 |
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From: Hao Luo <haoluo@google.com> |
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Date: Wed, 16 Feb 2022 14:52:02 -0800 |
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Subject: bpf: Replace ARG_XXX_OR_NULL with ARG_XXX | PTR_MAYBE_NULL |
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To: Greg KH <gregkh@linuxfoundation.org> |
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Cc: Alexei Starovoitov <ast@kernel.org>, Andrii Nakryiko <andrii@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, laura@labbott.name, stable@vger.kernel.org, Hao Luo <haoluo@google.com> |
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Message-ID: <20220216225209.2196865-3-haoluo@google.com> |
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|
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From: Hao Luo <haoluo@google.com> |
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|
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commit 48946bd6a5d695c50b34546864b79c1f910a33c1 upstream. |
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|
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We have introduced a new type to make bpf_arg composable, by |
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reserving high bits of bpf_arg to represent flags of a type. |
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|
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One of the flags is PTR_MAYBE_NULL which indicates a pointer |
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may be NULL. When applying this flag to an arg_type, it means |
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the arg can take NULL pointer. This patch switches the |
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qualified arg_types to use this flag. The arg_types changed |
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in this patch include: |
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|
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1. ARG_PTR_TO_MAP_VALUE_OR_NULL |
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2. ARG_PTR_TO_MEM_OR_NULL |
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3. ARG_PTR_TO_CTX_OR_NULL |
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4. ARG_PTR_TO_SOCKET_OR_NULL |
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5. ARG_PTR_TO_ALLOC_MEM_OR_NULL |
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6. ARG_PTR_TO_STACK_OR_NULL |
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|
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This patch does not eliminate the use of these arg_types, instead |
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it makes them an alias to the 'ARG_XXX | PTR_MAYBE_NULL'. |
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|
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Signed-off-by: Hao Luo <haoluo@google.com> |
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Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Link: https://lore.kernel.org/bpf/20211217003152.48334-3-haoluo@google.com |
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Cc: stable@vger.kernel.org # 5.16.x |
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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--- |
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include/linux/bpf.h | 15 +++++++++------ |
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kernel/bpf/verifier.c | 39 ++++++++++++++------------------------- |
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2 files changed, 23 insertions(+), 31 deletions(-) |
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|
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--- a/include/linux/bpf.h |
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+++ b/include/linux/bpf.h |
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@@ -331,13 +331,11 @@ enum bpf_arg_type { |
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ARG_PTR_TO_MAP_KEY, /* pointer to stack used as map key */ |
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ARG_PTR_TO_MAP_VALUE, /* pointer to stack used as map value */ |
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ARG_PTR_TO_UNINIT_MAP_VALUE, /* pointer to valid memory used to store a map value */ |
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- ARG_PTR_TO_MAP_VALUE_OR_NULL, /* pointer to stack used as map value or NULL */ |
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|
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/* the following constraints used to prototype bpf_memcmp() and other |
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* functions that access data on eBPF program stack |
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*/ |
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ARG_PTR_TO_MEM, /* pointer to valid memory (stack, packet, map value) */ |
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- ARG_PTR_TO_MEM_OR_NULL, /* pointer to valid memory or NULL */ |
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ARG_PTR_TO_UNINIT_MEM, /* pointer to memory does not need to be initialized, |
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* helper function must fill all bytes or clear |
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* them in error case. |
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@@ -347,26 +345,31 @@ enum bpf_arg_type { |
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ARG_CONST_SIZE_OR_ZERO, /* number of bytes accessed from memory or 0 */ |
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|
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ARG_PTR_TO_CTX, /* pointer to context */ |
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- ARG_PTR_TO_CTX_OR_NULL, /* pointer to context or NULL */ |
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ARG_ANYTHING, /* any (initialized) argument is ok */ |
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ARG_PTR_TO_SPIN_LOCK, /* pointer to bpf_spin_lock */ |
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ARG_PTR_TO_SOCK_COMMON, /* pointer to sock_common */ |
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ARG_PTR_TO_INT, /* pointer to int */ |
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ARG_PTR_TO_LONG, /* pointer to long */ |
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ARG_PTR_TO_SOCKET, /* pointer to bpf_sock (fullsock) */ |
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- ARG_PTR_TO_SOCKET_OR_NULL, /* pointer to bpf_sock (fullsock) or NULL */ |
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ARG_PTR_TO_BTF_ID, /* pointer to in-kernel struct */ |
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ARG_PTR_TO_ALLOC_MEM, /* pointer to dynamically allocated memory */ |
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- ARG_PTR_TO_ALLOC_MEM_OR_NULL, /* pointer to dynamically allocated memory or NULL */ |
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ARG_CONST_ALLOC_SIZE_OR_ZERO, /* number of allocated bytes requested */ |
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ARG_PTR_TO_BTF_ID_SOCK_COMMON, /* pointer to in-kernel sock_common or bpf-mirrored bpf_sock */ |
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ARG_PTR_TO_PERCPU_BTF_ID, /* pointer to in-kernel percpu type */ |
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ARG_PTR_TO_FUNC, /* pointer to a bpf program function */ |
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- ARG_PTR_TO_STACK_OR_NULL, /* pointer to stack or NULL */ |
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+ ARG_PTR_TO_STACK, /* pointer to stack */ |
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ARG_PTR_TO_CONST_STR, /* pointer to a null terminated read-only string */ |
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ARG_PTR_TO_TIMER, /* pointer to bpf_timer */ |
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__BPF_ARG_TYPE_MAX, |
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|
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+ /* Extended arg_types. */ |
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+ ARG_PTR_TO_MAP_VALUE_OR_NULL = PTR_MAYBE_NULL | ARG_PTR_TO_MAP_VALUE, |
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+ ARG_PTR_TO_MEM_OR_NULL = PTR_MAYBE_NULL | ARG_PTR_TO_MEM, |
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+ ARG_PTR_TO_CTX_OR_NULL = PTR_MAYBE_NULL | ARG_PTR_TO_CTX, |
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+ ARG_PTR_TO_SOCKET_OR_NULL = PTR_MAYBE_NULL | ARG_PTR_TO_SOCKET, |
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+ ARG_PTR_TO_ALLOC_MEM_OR_NULL = PTR_MAYBE_NULL | ARG_PTR_TO_ALLOC_MEM, |
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+ ARG_PTR_TO_STACK_OR_NULL = PTR_MAYBE_NULL | ARG_PTR_TO_STACK, |
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+ |
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/* This must be the last entry. Its purpose is to ensure the enum is |
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* wide enough to hold the higher bits reserved for bpf_type_flag. |
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*/ |
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--- a/kernel/bpf/verifier.c |
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+++ b/kernel/bpf/verifier.c |
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@@ -472,14 +472,9 @@ static bool arg_type_may_be_refcounted(e |
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return type == ARG_PTR_TO_SOCK_COMMON; |
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} |
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|
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-static bool arg_type_may_be_null(enum bpf_arg_type type) |
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+static bool type_may_be_null(u32 type) |
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{ |
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- return type == ARG_PTR_TO_MAP_VALUE_OR_NULL || |
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- type == ARG_PTR_TO_MEM_OR_NULL || |
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- type == ARG_PTR_TO_CTX_OR_NULL || |
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- type == ARG_PTR_TO_SOCKET_OR_NULL || |
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- type == ARG_PTR_TO_ALLOC_MEM_OR_NULL || |
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- type == ARG_PTR_TO_STACK_OR_NULL; |
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+ return type & PTR_MAYBE_NULL; |
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} |
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|
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/* Determine whether the function releases some resources allocated by another |
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@@ -4963,9 +4958,8 @@ static int process_timer_func(struct bpf |
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|
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static bool arg_type_is_mem_ptr(enum bpf_arg_type type) |
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{ |
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- return type == ARG_PTR_TO_MEM || |
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- type == ARG_PTR_TO_MEM_OR_NULL || |
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- type == ARG_PTR_TO_UNINIT_MEM; |
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+ return base_type(type) == ARG_PTR_TO_MEM || |
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+ base_type(type) == ARG_PTR_TO_UNINIT_MEM; |
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} |
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|
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static bool arg_type_is_mem_size(enum bpf_arg_type type) |
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@@ -5102,31 +5096,26 @@ static const struct bpf_reg_types *compa |
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[ARG_PTR_TO_MAP_KEY] = &map_key_value_types, |
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[ARG_PTR_TO_MAP_VALUE] = &map_key_value_types, |
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[ARG_PTR_TO_UNINIT_MAP_VALUE] = &map_key_value_types, |
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- [ARG_PTR_TO_MAP_VALUE_OR_NULL] = &map_key_value_types, |
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[ARG_CONST_SIZE] = &scalar_types, |
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[ARG_CONST_SIZE_OR_ZERO] = &scalar_types, |
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[ARG_CONST_ALLOC_SIZE_OR_ZERO] = &scalar_types, |
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[ARG_CONST_MAP_PTR] = &const_map_ptr_types, |
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[ARG_PTR_TO_CTX] = &context_types, |
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- [ARG_PTR_TO_CTX_OR_NULL] = &context_types, |
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[ARG_PTR_TO_SOCK_COMMON] = &sock_types, |
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#ifdef CONFIG_NET |
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[ARG_PTR_TO_BTF_ID_SOCK_COMMON] = &btf_id_sock_common_types, |
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#endif |
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[ARG_PTR_TO_SOCKET] = &fullsock_types, |
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- [ARG_PTR_TO_SOCKET_OR_NULL] = &fullsock_types, |
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[ARG_PTR_TO_BTF_ID] = &btf_ptr_types, |
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[ARG_PTR_TO_SPIN_LOCK] = &spin_lock_types, |
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[ARG_PTR_TO_MEM] = &mem_types, |
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- [ARG_PTR_TO_MEM_OR_NULL] = &mem_types, |
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[ARG_PTR_TO_UNINIT_MEM] = &mem_types, |
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[ARG_PTR_TO_ALLOC_MEM] = &alloc_mem_types, |
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- [ARG_PTR_TO_ALLOC_MEM_OR_NULL] = &alloc_mem_types, |
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[ARG_PTR_TO_INT] = &int_ptr_types, |
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[ARG_PTR_TO_LONG] = &int_ptr_types, |
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[ARG_PTR_TO_PERCPU_BTF_ID] = &percpu_btf_ptr_types, |
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[ARG_PTR_TO_FUNC] = &func_ptr_types, |
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- [ARG_PTR_TO_STACK_OR_NULL] = &stack_ptr_types, |
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+ [ARG_PTR_TO_STACK] = &stack_ptr_types, |
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[ARG_PTR_TO_CONST_STR] = &const_str_ptr_types, |
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[ARG_PTR_TO_TIMER] = &timer_types, |
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}; |
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@@ -5140,7 +5129,7 @@ static int check_reg_type(struct bpf_ver |
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const struct bpf_reg_types *compatible; |
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int i, j; |
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|
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- compatible = compatible_reg_types[arg_type]; |
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+ compatible = compatible_reg_types[base_type(arg_type)]; |
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if (!compatible) { |
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verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type); |
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return -EFAULT; |
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@@ -5221,15 +5210,14 @@ static int check_func_arg(struct bpf_ver |
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return -EACCES; |
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} |
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|
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- if (arg_type == ARG_PTR_TO_MAP_VALUE || |
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- arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE || |
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- arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) { |
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+ if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE || |
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+ base_type(arg_type) == ARG_PTR_TO_UNINIT_MAP_VALUE) { |
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err = resolve_map_arg_type(env, meta, &arg_type); |
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if (err) |
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return err; |
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} |
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|
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- if (register_is_null(reg) && arg_type_may_be_null(arg_type)) |
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+ if (register_is_null(reg) && type_may_be_null(arg_type)) |
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/* A NULL register has a SCALAR_VALUE type, so skip |
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* type checking. |
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*/ |
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@@ -5298,10 +5286,11 @@ skip_type_check: |
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err = check_helper_mem_access(env, regno, |
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meta->map_ptr->key_size, false, |
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NULL); |
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- } else if (arg_type == ARG_PTR_TO_MAP_VALUE || |
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- (arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL && |
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- !register_is_null(reg)) || |
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- arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE) { |
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+ } else if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE || |
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+ base_type(arg_type) == ARG_PTR_TO_UNINIT_MAP_VALUE) { |
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+ if (type_may_be_null(arg_type) && register_is_null(reg)) |
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+ return 0; |
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+ |
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/* bpf_map_xxx(..., map_ptr, ..., value) call: |
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* check [value, value + map->value_size) validity |
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*/ |
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