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bpf: btf: Use exact btf value_size match in map_check_btf() 

The current map_check_btf() in BPF_MAP_TYPE_ARRAY rejects
'> map->value_size' to ensure map_seq_show_elem() will not
access things beyond an array element.

Yonghong suggested that using '!=' is a more correct
check.  The 8 bytes round_up on value_size is stored
in array->elem_size.  Hence, using '!=' on map->value_size
is a proper check.

This patch also adds new tests to check the btf array
key type and value type.  Two of these new tests verify
the btf's value_size (the change in this patch).

It also fixes two existing tests that wrongly encoded
a btf's type size (pprint_test) and the value_type_id (in one
of the raw_tests[]).  However, that do not affect these two
BTF verification tests before or after this test changes.
These two tests mainly failed at array creation time after
this patch.

Fixes: a26ca7c982 ("bpf: btf: Add pretty print support to the basic arraymap")
Suggested-by: Yonghong Song <yhs@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Martin KaFai Lau 2018-07-26 09:57:59 -07:00 committed by Daniel Borkmann
parent 36e0f12bbf
commit 5f300e8004
2 changed files with 85 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/bpf/arraymap.c
View File

@ -378,7 +378,7 @@ static int array_map_check_btf(const struct bpf_map *map, const struct btf *btf,
return -EINVAL;
value_type = btf_type_id_size(btf, &btf_value_id, &value_size);
if (!value_type || value_size > map->value_size)
if (!value_type || value_size != map->value_size)
return -EINVAL;
return 0;

86
tools/testing/selftests/bpf/test_btf.c
View File

@ -507,7 +507,7 @@ static struct btf_raw_test raw_tests[] = {
.key_size = sizeof(int),
.value_size = sizeof(void *) * 4,
.key_type_id = 1,
.value_type_id = 4,
.value_type_id = 5,
.max_entries = 4,
},
@ -1292,6 +1292,88 @@ static struct btf_raw_test raw_tests[] = {
.err_str = "type != 0",
},
{
.descr = "arraymap invalid btf key (a bit field)",
.raw_types = {
/* int */ /* [1] */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
/* 32 bit int with 32 bit offset */ /* [2] */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 32, 32, 8),
BTF_END_RAW,
},
.str_sec = "",
.str_sec_size = sizeof(""),
.map_type = BPF_MAP_TYPE_ARRAY,
.map_name = "array_map_check_btf",
.key_size = sizeof(int),
.value_size = sizeof(int),
.key_type_id = 2,
.value_type_id = 1,
.max_entries = 4,
.map_create_err = true,
},
{
.descr = "arraymap invalid btf key (!= 32 bits)",
.raw_types = {
/* int */ /* [1] */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
/* 16 bit int with 0 bit offset */ /* [2] */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 16, 2),
BTF_END_RAW,
},
.str_sec = "",
.str_sec_size = sizeof(""),
.map_type = BPF_MAP_TYPE_ARRAY,
.map_name = "array_map_check_btf",
.key_size = sizeof(int),
.value_size = sizeof(int),
.key_type_id = 2,
.value_type_id = 1,
.max_entries = 4,
.map_create_err = true,
},
{
.descr = "arraymap invalid btf value (too small)",
.raw_types = {
/* int */ /* [1] */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
BTF_END_RAW,
},
.str_sec = "",
.str_sec_size = sizeof(""),
.map_type = BPF_MAP_TYPE_ARRAY,
.map_name = "array_map_check_btf",
.key_size = sizeof(int),
/* btf_value_size < map->value_size */
.value_size = sizeof(__u64),
.key_type_id = 1,
.value_type_id = 1,
.max_entries = 4,
.map_create_err = true,
},
{
.descr = "arraymap invalid btf value (too big)",
.raw_types = {
/* int */ /* [1] */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
BTF_END_RAW,
},
.str_sec = "",
.str_sec_size = sizeof(""),
.map_type = BPF_MAP_TYPE_ARRAY,
.map_name = "array_map_check_btf",
.key_size = sizeof(int),
/* btf_value_size > map->value_size */
.value_size = sizeof(__u16),
.key_type_id = 1,
.value_type_id = 1,
.max_entries = 4,
.map_create_err = true,
},
}; /* struct btf_raw_test raw_tests[] */
static const char *get_next_str(const char *start, const char *end)
@ -2051,7 +2133,7 @@ static struct btf_raw_test pprint_test = {
BTF_ENUM_ENC(NAME_TBD, 2),
BTF_ENUM_ENC(NAME_TBD, 3),
/* struct pprint_mapv */ /* [16] */
BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 8), 28),
BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 8), 32),
BTF_MEMBER_ENC(NAME_TBD, 11, 0), /* uint32_t ui32 */
BTF_MEMBER_ENC(NAME_TBD, 10, 32), /* uint16_t ui16 */
BTF_MEMBER_ENC(NAME_TBD, 12, 64), /* int32_t si32 */