aboutsummaryrefslogtreecommitdiffstats
path: root/kernel/bpf/btf.c (follow)
AgeCommit message (Collapse)AuthorFilesLines
2018-10-09bpf: btf: Fix a missing check bugWenwen Wang1-0/+3
In btf_parse_hdr(), the length of the btf data header is firstly copied from the user space to 'hdr_len' and checked to see whether it is larger than 'btf_data_size'. If yes, an error code EINVAL is returned. Otherwise, the whole header is copied again from the user space to 'btf->hdr'. However, after the second copy, there is no check between 'btf->hdr->hdr_len' and 'hdr_len' to confirm that the two copies get the same value. Given that the btf data is in the user space, a malicious user can race to change the data between the two copies. By doing so, the user can provide malicious data to the kernel and cause undefined behavior. This patch adds a necessary check after the second copy, to make sure 'btf->hdr->hdr_len' has the same value as 'hdr_len'. Otherwise, an error code EINVAL will be returned. Signed-off-by: Wenwen Wang <wang6495@umn.edu> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-09-12bpf: btf: Fix end boundary calculation for type sectionMartin KaFai Lau1-1/+1
The end boundary math for type section is incorrect in btf_check_all_metas(). It just happens that hdr->type_off is always 0 for now because there are only two sections (type and string) and string section must be at the end (ensured in btf_parse_str_sec). However, type_off may not be 0 if a new section would be added later. This patch fixes it. Fixes: f80442a4cd18 ("bpf: btf: Change how section is supported in btf_header") Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-07-24bpf: btf: Ensure the member->offset is in the right orderMartin KaFai Lau1-1/+13
This patch ensures the member->offset of a struct is in the correct order (i.e the later member's offset cannot go backward). The current "pahole -J" BTF encoder does not generate something like this. However, checking this can ensure future encoder will not violate this. Fixes: 69b693f0aefa ("bpf: btf: Introduce BPF Type Format (BTF)") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-07-20bpf: btf: Clean up BTF_INT_BITS() in uapi btf.hMartin KaFai Lau1-6/+10
This patch shrinks the BTF_INT_BITS() mask. The current btf_int_check_meta() ensures the nr_bits of an integer cannot exceed 64. Hence, it is mostly an uapi cleanup. The actual btf usage (i.e. seq_show()) is also modified to use u8 instead of u16. The verification (e.g. btf_int_check_meta()) path stays as is to deal with invalid BTF situation. Fixes: 69b693f0aefa ("bpf: btf: Introduce BPF Type Format (BTF)") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-07-11bpf: btf: Fix bitfield extraction for big endianOkash Khawaja1-17/+13
When extracting bitfield from a number, btf_int_bits_seq_show() builds a mask and accesses least significant byte of the number in a way specific to little-endian. This patch fixes that by checking endianness of the machine and then shifting left and right the unneeded bits. Thanks to Martin Lau for the help in navigating potential pitfalls when dealing with endianess and for the final solution. Fixes: b00b8daec828 ("bpf: btf: Add pretty print capability for data with BTF type info") Signed-off-by: Okash Khawaja <osk@fb.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-06-12treewide: kvzalloc() -> kvcalloc()Kees Cook1-4/+4
The kvzalloc() function has a 2-factor argument form, kvcalloc(). This patch replaces cases of: kvzalloc(a * b, gfp) with: kvcalloc(a * b, gfp) as well as handling cases of: kvzalloc(a * b * c, gfp) with: kvzalloc(array3_size(a, b, c), gfp) as it's slightly less ugly than: kvcalloc(array_size(a, b), c, gfp) This does, however, attempt to ignore constant size factors like: kvzalloc(4 * 1024, gfp) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( kvzalloc( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | kvzalloc( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( kvzalloc( - sizeof(u8) * (COUNT) + COUNT , ...) | kvzalloc( - sizeof(__u8) * (COUNT) + COUNT , ...) | kvzalloc( - sizeof(char) * (COUNT) + COUNT , ...) | kvzalloc( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | kvzalloc( - sizeof(u8) * COUNT + COUNT , ...) | kvzalloc( - sizeof(__u8) * COUNT + COUNT , ...) | kvzalloc( - sizeof(char) * COUNT + COUNT , ...) | kvzalloc( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( - kvzalloc + kvcalloc ( - sizeof(TYPE) * (COUNT_ID) + COUNT_ID, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(TYPE) * COUNT_ID + COUNT_ID, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(TYPE) * (COUNT_CONST) + COUNT_CONST, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(TYPE) * COUNT_CONST + COUNT_CONST, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * (COUNT_ID) + COUNT_ID, sizeof(THING) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * COUNT_ID + COUNT_ID, sizeof(THING) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * (COUNT_CONST) + COUNT_CONST, sizeof(THING) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * COUNT_CONST + COUNT_CONST, sizeof(THING) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ - kvzalloc + kvcalloc ( - SIZE * COUNT + COUNT, SIZE , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( kvzalloc( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kvzalloc( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kvzalloc( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kvzalloc( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kvzalloc( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kvzalloc( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kvzalloc( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kvzalloc( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( kvzalloc( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kvzalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kvzalloc( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kvzalloc( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kvzalloc( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | kvzalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( kvzalloc( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products, // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( kvzalloc(C1 * C2 * C3, ...) | kvzalloc( - (E1) * E2 * E3 + array3_size(E1, E2, E3) , ...) | kvzalloc( - (E1) * (E2) * E3 + array3_size(E1, E2, E3) , ...) | kvzalloc( - (E1) * (E2) * (E3) + array3_size(E1, E2, E3) , ...) | kvzalloc( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants, // keeping sizeof() as the second factor argument. @@ expression THING, E1, E2; type TYPE; constant C1, C2, C3; @@ ( kvzalloc(sizeof(THING) * C2, ...) | kvzalloc(sizeof(TYPE) * C2, ...) | kvzalloc(C1 * C2 * C3, ...) | kvzalloc(C1 * C2, ...) | - kvzalloc + kvcalloc ( - sizeof(TYPE) * (E2) + E2, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(TYPE) * E2 + E2, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * (E2) + E2, sizeof(THING) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * E2 + E2, sizeof(THING) , ...) | - kvzalloc + kvcalloc ( - (E1) * E2 + E1, E2 , ...) | - kvzalloc + kvcalloc ( - (E1) * (E2) + E1, E2 , ...) | - kvzalloc + kvcalloc ( - E1 * E2 + E1, E2 , ...) ) Signed-off-by: Kees Cook <keescook@chromium.org>
2018-06-02bpf: btf: Ensure t->type == 0 for BTF_KIND_FWDMartin KaFai Lau1-1/+20
The t->type in BTF_KIND_FWD is not used. It must be 0. This patch ensures that and also adds a test case in test_btf.c Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-06-02bpf: btf: Check array t->sizeMartin KaFai Lau1-0/+5
This patch ensures array's t->size is 0. The array size is decided by its individual elem's size and the number of elements. Hence, t->size is not used and it must be 0. A test case is added to test_btf.c Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-05-28bpf: btf: avoid -Wreturn-type warningArnd Bergmann1-1/+1
gcc warns about a noreturn function possibly returning in some configurations: kernel/bpf/btf.c: In function 'env_type_is_resolve_sink': kernel/bpf/btf.c:729:1: error: control reaches end of non-void function [-Werror=return-type] Using BUG() instead of BUG_ON() avoids that warning and otherwise does the exact same thing. Fixes: eb3f595dab40 ("bpf: btf: Validate type reference") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-05-24bpf: btf: Avoid variable length arrayMartin KaFai Lau1-6/+5
Sparse warning: kernel/bpf/btf.c:1985:34: warning: Variable length array is used. This patch directly uses ARRAY_SIZE(). Fixes: f80442a4cd18 ("bpf: btf: Change how section is supported in btf_header") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-05-23bpf: btf: Remove unused bits from uapi/linux/btf.hMartin KaFai Lau1-17/+35
This patch does the followings: 1. Limit BTF_MAX_TYPES and BTF_MAX_NAME_OFFSET to 64k. We can raise it later. 2. Remove the BTF_TYPE_PARENT and BTF_STR_TBL_ELF_ID. They are currently encoded at the highest bit of a u32. It is because the current use case does not require supporting parent type (i.e type_id referring to a type in another BTF file). It also does not support referring to a string in ELF. The BTF_TYPE_PARENT and BTF_STR_TBL_ELF_ID checks are replaced by BTF_TYPE_ID_CHECK and BTF_STR_OFFSET_CHECK which are defined in btf.c instead of uapi/linux/btf.h. 3. Limit the BTF_INFO_KIND from 5 bits to 4 bits which is enough. There is unused bits headroom if we ever needed it later. 4. The root bit in BTF_INFO is also removed because it is not used in the current use case. 5. Remove BTF_INT_VARARGS since func type is not supported now. The BTF_INT_ENCODING is limited to 4 bits instead of 8 bits. The above can be added back later because the verifier ensures the unused bits are zeros. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-05-23bpf: btf: Check array->index_typeMartin KaFai Lau1-24/+56
Instead of ingoring the array->index_type field. Enforce that it must be a BTF_KIND_INT in size 1/2/4/8 bytes. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-05-23bpf: btf: Change how section is supported in btf_headerMartin KaFai Lau1-51/+158
There are currently unused section descriptions in the btf_header. Those sections are here to support future BTF use cases. For example, the func section (func_off) is to support function signature (e.g. the BPF prog function signature). Instead of spelling out all potential sections up-front in the btf_header. This patch makes changes to btf_header such that extending it (e.g. adding a section) is possible later. The unused ones can be removed for now and they can be added back later. This patch: 1. adds a hdr_len to the btf_header. It will allow adding sections (and other info like parent_label and parent_name) later. The check is similar to the existing bpf_attr. If a user passes in a longer hdr_len, the kernel ensures the extra tailing bytes are 0. 2. allows the section order in the BTF object to be different from its sec_off order in btf_header. 3. each sec_off is followed by a sec_len. It must not have gap or overlapping among sections. The string section is ensured to be at the end due to the 4 bytes alignment requirement of the type section. The above changes will allow enough flexibility to add new sections (and other info) to the btf_header later. This patch also removes an unnecessary !err check at the end of btf_parse(). Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-05-09bpf: btf: Add struct bpf_btf_infoMartin KaFai Lau1-5/+21
During BPF_OBJ_GET_INFO_BY_FD on a btf_fd, the current bpf_attr's info.info is directly filled with the BTF binary data. It is not extensible. In this case, we want to add BTF ID. This patch adds "struct bpf_btf_info" which has the BTF ID as one of its member. The BTF binary data itself is exposed through the "btf" and "btf_size" members. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-05-09bpf: btf: Introduce BTF IDMartin KaFai Lau1-10/+98
This patch gives an ID to each loaded BTF. The ID is allocated by the idr like the existing prog-id and map-id. The bpf_put(map->btf) is moved to __bpf_map_put() so that the userspace can stop seeing the BTF ID ASAP when the last BTF refcnt is gone. It also makes BTF accessible from userspace through the 1. new BPF_BTF_GET_FD_BY_ID command. It is limited to CAP_SYS_ADMIN which is inline with the BPF_BTF_LOAD cmd and the existing BPF_[MAP|PROG]_GET_FD_BY_ID cmd. 2. new btf_id (and btf_key_id + btf_value_id) in "struct bpf_map_info" Once the BTF ID handler is accessible from userspace, freeing a BTF object has to go through a rcu period. The BPF_BTF_GET_FD_BY_ID cmd can then be done under a rcu_read_lock() instead of taking spin_lock. [Note: A similar rcu usage can be done to the existing bpf_prog_get_fd_by_id() in a follow up patch] When processing the BPF_BTF_GET_FD_BY_ID cmd, refcount_inc_not_zero() is needed because the BTF object could be already in the rcu dead row . btf_get() is removed since its usage is currently limited to btf.c alone. refcount_inc() is used directly instead. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-05-09bpf: btf: Avoid WARN_ON when CONFIG_REFCOUNT_FULL=yMartin KaFai Lau1-1/+1
If CONFIG_REFCOUNT_FULL=y, refcount_inc() WARN when refcount is 0. When creating a new btf, the initial btf->refcnt is 0 and triggered the following: [ 34.855452] refcount_t: increment on 0; use-after-free. [ 34.856252] WARNING: CPU: 6 PID: 1857 at lib/refcount.c:153 refcount_inc+0x26/0x30 .... [ 34.868809] Call Trace: [ 34.869168] btf_new_fd+0x1af6/0x24d0 [ 34.869645] ? btf_type_seq_show+0x200/0x200 [ 34.870212] ? lock_acquire+0x3b0/0x3b0 [ 34.870726] ? security_capable+0x54/0x90 [ 34.871247] __x64_sys_bpf+0x1b2/0x310 [ 34.871761] ? __ia32_sys_bpf+0x310/0x310 [ 34.872285] ? bad_area_access_error+0x310/0x310 [ 34.872894] do_syscall_64+0x95/0x3f0 This patch uses refcount_set() instead. Reported-by: Yonghong Song <yhs@fb.com> Tested-by: Yonghong Song <yhs@fb.com> Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-23bpf: btf: Clean up btf.h in uapiMartin KaFai Lau1-10/+10
This patch cleans up btf.h in uapi: 1) Rename "name" to "name_off" to better reflect it is an offset to the string section instead of a char array. 2) Remove unused value BTF_FLAGS_COMPR and BTF_MAGIC_SWAP Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-19bpf: btf: Add BPF_OBJ_GET_INFO_BY_FD support to BTF fdMartin KaFai Lau1-1/+16
This patch adds BPF_OBJ_GET_INFO_BY_FD support to BTF fd. The original BTF data, which was used to create the BTF fd during the earlier BPF_BTF_LOAD call, will be returned. The userspace is expected to allocate buffer to info.info and the buffer size is set to info.info_len before calling BPF_OBJ_GET_INFO_BY_FD. The original BTF data is copied to the userspace buffer (info.info). Only upto the user's specified info.info_len will be copied. The original BTF data size is set to info.info_len. The userspace needs to check if it is bigger than its allocated buffer size. If it is, the userspace should realloc with the kernel-returned info.info_len and call the BPF_OBJ_GET_INFO_BY_FD again. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-19bpf: btf: Add BPF_BTF_LOAD commandMartin KaFai Lau1-0/+67
This patch adds a BPF_BTF_LOAD command which 1) loads and verifies the BTF (implemented in earlier patches) 2) returns a BTF fd to userspace. In the next patch, the BTF fd can be specified during BPF_MAP_CREATE. It currently limits to CAP_SYS_ADMIN. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-19bpf: btf: Add pretty print capability for data with BTF type infoMartin KaFai Lau1-0/+198
This patch adds pretty print capability for data with BTF type info. The current usage is to allow pretty print for a BPF map. The next few patches will allow a read() on a pinned map with BTF type info for its key and value. This patch uses the seq_printf() infra. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-19bpf: btf: Check members of struct/unionMartin KaFai Lau1-0/+205
This patch checks a few things of struct's members: 1) It has a valid size (e.g. a "const void" is invalid) 2) A member's size (+ its member's offset) does not exceed the containing struct's size. 3) The member's offset satisfies the alignment requirement The above can only be done after the needs_resolve member's type is resolved. Hence, the above is done together in btf_struct_resolve(). Each possible member's type (e.g. int, enum, modifier...) implements the check_member() ops which will be called from btf_struct_resolve(). Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-19bpf: btf: Validate type referenceMartin KaFai Lau1-1/+665
After collecting all btf_type in the first pass in an earlier patch, the second pass (in this patch) can validate the reference types (e.g. the referring type does exist and it does not refer to itself). While checking the reference type, it also gathers other information (e.g. the size of an array). This info will be useful in checking the struct's members in a later patch. They will also be useful in doing pretty print later. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-19bpf: btf: Introduce BPF Type Format (BTF)Martin KaFai Lau1-0/+915
This patch introduces BPF type Format (BTF). BTF (BPF Type Format) is the meta data format which describes the data types of BPF program/map. Hence, it basically focus on the C programming language which the modern BPF is primary using. The first use case is to provide a generic pretty print capability for a BPF map. BTF has its root from CTF (Compact C-Type format). To simplify the handling of BTF data, BTF removes the differences between small and big type/struct-member. Hence, BTF consistently uses u32 instead of supporting both "one u16" and "two u32 (+padding)" in describing type and struct-member. It also raises the number of types (and functions) limit from 0x7fff to 0x7fffffff. Due to the above changes, the format is not compatible to CTF. Hence, BTF starts with a new BTF_MAGIC and version number. This patch does the first verification pass to the BTF. The first pass checks: 1. meta-data size (e.g. It does not go beyond the total btf's size) 2. name_offset is valid 3. Each BTF_KIND (e.g. int, enum, struct....) does its own check of its meta-data. Some other checks, like checking a struct's member is referring to a valid type, can only be done in the second pass. The second verification pass will be implemented in the next patch. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.