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2024-09-10bpftool: Fix undefined behavior in qsort(NULL, 0, ...)Kuan-Wei Chiu1-0/+3
When netfilter has no entry to display, qsort is called with qsort(NULL, 0, ...). This results in undefined behavior, as UBSan reports: net.c:827:2: runtime error: null pointer passed as argument 1, which is declared to never be null Although the C standard does not explicitly state whether calling qsort with a NULL pointer when the size is 0 constitutes undefined behavior, Section 7.1.4 of the C standard (Use of library functions) mentions: "Each of the following statements applies unless explicitly stated otherwise in the detailed descriptions that follow: If an argument to a function has an invalid value (such as a value outside the domain of the function, or a pointer outside the address space of the program, or a null pointer, or a pointer to non-modifiable storage when the corresponding parameter is not const-qualified) or a type (after promotion) not expected by a function with variable number of arguments, the behavior is undefined." To avoid this, add an early return when nf_link_info is NULL to prevent calling qsort with a NULL pointer. Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240910150207.3179306-1-visitorckw@gmail.com
2024-09-10bpftool: Fix typosAndrew Kreimer1-1/+1
Fix typos in documentation. Reported-by: Matthew Wilcox <willy@infradead.org> Reported-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Andrew Kreimer <algonell@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240909092452.4293-1-algonell@gmail.com
2024-09-10bpftool: Fix undefined behavior caused by shifting into the sign bitKuan-Wei Chiu1-4/+4
Replace shifts of '1' with '1U' in bitwise operations within __show_dev_tc_bpf() to prevent undefined behavior caused by shifting into the sign bit of a signed integer. By using '1U', the operations are explicitly performed on unsigned integers, avoiding potential integer overflow or sign-related issues. Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240908140009.3149781-1-visitorckw@gmail.com
2024-09-07bpftool: Improve btf c dump sorting stabilityMykyta Yatsenko1-5/+75
Existing algorithm for BTF C dump sorting uses only types and names of the structs and unions for ordering. As dump contains structs with the same names but different contents, relative to each other ordering of those structs will be accidental. This patch addresses this problem by introducing a new sorting field that contains hash of the struct/union field names and types to disambiguate comparison of the non-unique named structs. Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240906132453.146085-1-mykyta.yatsenko5@gmail.com
2024-09-05bpftool: fix some typos in bpftoolLin Yikai2-6/+6
Hi, fix some spelling errors in bpftool, the details are as follows: -in file "bpftool-gen.rst" libppf->libbpf -in the code comments: ouptut->output Signed-off-by: Lin Yikai <yikai.lin@vivo.com> Link: https://lore.kernel.org/r/20240905110354.3274546-2-yikai.lin@vivo.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-09-02bpftool: Fix handling enum64 in btf dump sortingMykyta Yatsenko1-3/+4
Wrong function is used to access the first enum64 element. Substituting btf_enum(t) with btf_enum64(t) for BTF_KIND_ENUM64. Fixes: 94133cf24bb3 ("bpftool: Introduce btf c dump sorting") Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240902171721.105253-1-mykyta.yatsenko5@gmail.com
2024-09-02bpftool: Add missing blank lines in bpftool-net doc exampleQuentin Monnet1-0/+2
In bpftool-net documentation, two blank lines are missing in a recently added example, causing docutils to complain: $ cd tools/bpf/bpftool $ make doc DESCEND Documentation GEN bpftool-btf.8 GEN bpftool-cgroup.8 GEN bpftool-feature.8 GEN bpftool-gen.8 GEN bpftool-iter.8 GEN bpftool-link.8 GEN bpftool-map.8 GEN bpftool-net.8 <stdin>:189: (INFO/1) Possible incomplete section title. Treating the overline as ordinary text because it's so short. <stdin>:192: (INFO/1) Blank line missing before literal block (after the "::")? Interpreted as a definition list item. <stdin>:199: (INFO/1) Possible incomplete section title. Treating the overline as ordinary text because it's so short. <stdin>:201: (INFO/1) Blank line missing before literal block (after the "::")? Interpreted as a definition list item. GEN bpftool-perf.8 GEN bpftool-prog.8 GEN bpftool.8 GEN bpftool-struct_ops.8 Add the missing blank lines. Fixes: 0d7c06125cea ("bpftool: Add document for net attach/detach on tcx subcommand") Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240901210742.25758-1-qmo@kernel.org
2024-07-30tools/bpf: Fix the wrong format specifierZhu Jun1-2/+2
The format specifier of "unsigned int" in printf() should be "%u", not "%d". Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240724111120.11625-1-zhujun2@cmss.chinamobile.com
2024-07-30tools/runqslower: Fix LDFLAGS and add LDLIBS supportTony Ambardar1-1/+2
Actually use previously defined LDFLAGS during build and add support for LDLIBS to link extra standalone libraries e.g. 'argp' which is not provided by musl libc. Fixes: 585bf4640ebe ("tools: runqslower: Add EXTRA_CFLAGS and EXTRA_LDFLAGS support") Signed-off-by: Tony Ambardar <tony.ambardar@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Ilya Leoshkevich <iii@linux.ibm.com> Link: https://lore.kernel.org/bpf/20240723003045.2273499-1-tony.ambardar@gmail.com
2024-07-29bpftool: Add document for net attach/detach on tcx subcommandTao Chen1-1/+21
This commit adds sample output for net attach/detach on tcx subcommand. Signed-off-by: Tao Chen <chen.dylane@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240721144252.96264-1-chen.dylane@gmail.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-07-29bpftool: Add bash-completion for tcx subcommandTao Chen1-1/+1
This commit adds bash-completion for attaching tcx program on interface. Signed-off-by: Tao Chen <chen.dylane@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240721144238.96246-1-chen.dylane@gmail.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-07-29bpftool: Add net attach/detach command to tcx progTao Chen1-1/+42
Now, attach/detach tcx prog supported in libbpf, so we can add new command 'bpftool attach/detach tcx' to attach tcx prog with bpftool for user. # bpftool prog load tc_prog.bpf.o /sys/fs/bpf/tc_prog # bpftool prog show ... 192: sched_cls name tc_prog tag 187aeb611ad00cfc gpl loaded_at 2024-07-11T15:58:16+0800 uid 0 xlated 152B jited 97B memlock 4096B map_ids 100,99,97 btf_id 260 # bpftool net attach tcx_ingress name tc_prog dev lo # bpftool net ... tc: lo(1) tcx/ingress tc_prog prog_id 29 # bpftool net detach tcx_ingress dev lo # bpftool net ... tc: # bpftool net attach tcx_ingress name tc_prog dev lo # bpftool net tc: lo(1) tcx/ingress tc_prog prog_id 29 Test environment: ubuntu_22_04, 6.7.0-060700-generic Signed-off-by: Tao Chen <chen.dylane@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240721144221.96228-1-chen.dylane@gmail.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-07-29bpftool: Refactor xdp attach/detach type judgmentTao Chen1-5/+21
This commit no logical changed, just increases code readability and facilitates TCX prog expansion, which will be implemented in the next patch. Signed-off-by: Tao Chen <chen.dylane@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240721143353.95980-2-chen.dylane@gmail.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-07-22tools/resolve_btfids: Fix comparison of distinct pointer types warning in ↵Liwei Song1-1/+1
resolve_btfids Add a type cast for set8->pairs to fix below compile warning: main.c: In function 'sets_patch': main.c:699:50: warning: comparison of distinct pointer types lacks a cast 699 | BUILD_BUG_ON(set8->pairs != &set8->pairs[0].id); | ^~ Fixes: 9707ac4fe2f5 ("tools/resolve_btfids: Refactor set sorting with types from btf_ids.h") Signed-off-by: Liwei Song <liwei.song.lsong@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/bpf/20240722083305.4009723-1-liwei.song.lsong@gmail.com
2024-07-17bpftool: Fix typo in usage helpDonald Hunter1-1/+1
The usage help for "bpftool prog help" contains a ° instead of the _ symbol for cgroup/sendmsg_unix. Fix the typo. Fixes: 8b3cba987e6d ("bpftool: Add support for cgroup unix socket address hooks") Signed-off-by: Donald Hunter <donald.hunter@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240717134508.77488-1-donald.hunter@gmail.com
2024-07-10bpftool: improve skeleton backwards compat with old buggy libbpfsAndrii Nakryiko1-14/+32
Old versions of libbpf don't handle varying sizes of bpf_map_skeleton struct correctly. As such, BPF skeleton generated by newest bpftool might not be compatible with older libbpf (though only when libbpf is used as a shared library), even though it, by design, should. Going forward libbpf will be fixed, plus we'll release bug fixed versions of relevant old libbpfs, but meanwhile try to mitigate from bpftool side by conservatively assuming older and smaller definition of bpf_map_skeleton, if possible. Meaning, if there are no struct_ops maps. If there are struct_ops, then presumably user would like to have auto-attaching logic and struct_ops map link placeholders, so use the full bpf_map_skeleton definition in that case. Acked-by: Quentin Monnet <qmo@kernel.org> Co-developed-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240708204540.4188946-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-07-02bpftool: Mount bpffs when pinmaps path not under the bpffsTao Chen1-0/+4
As Quentin said [0], BPF map pinning will fail if the pinmaps path is not under the bpffs, like: libbpf: specified path /home/ubuntu/test/sock_ops_map is not on BPF FS Error: failed to pin all maps [0] https://github.com/libbpf/bpftool/issues/146 Fixes: 3767a94b3253 ("bpftool: add pinmaps argument to the load/loadall") Signed-off-by: Tao Chen <chen.dylane@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Quentin Monnet <qmo@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240702131150.15622-1-chen.dylane@gmail.com
2024-06-21bpftool: Allow compile-time checks of BPF map auto-attach support in skeletonAndrii Nakryiko1-0/+2
New versions of bpftool now emit additional link placeholders for BPF maps (struct_ops maps are the only maps right now that support attachment), and set up BPF skeleton in such a way that libbpf will auto-attach BPF maps automatically, assumming libbpf is recent enough (v1.5+). Old libbpf will do nothing with those links and won't attempt to auto-attach maps. This allows user code to handle both pre-v1.5 and v1.5+ versions of libbpf at runtime, if necessary. But if users don't have (or don't want to) control bpftool version that generates skeleton, then they can't just assume that skeleton will have link placeholders. To make this detection possible and easy, let's add the following to generated skeleton header file: #define BPF_SKEL_SUPPORTS_MAP_AUTO_ATTACH 1 This can be used during compilation time to guard code that accesses skel->links.<map> slots. Note, if auto-attachment is undesirable, libbpf allows to disable this through bpf_map__set_autoattach(map, false). This is necessary only on libbpf v1.5+, older libbpf doesn't support map auto-attach anyways. Libbpf version can be detected at compilation time using LIBBPF_MAJOR_VERSION and LIBBPF_MINOR_VERSION macros, or at runtime with libbpf_major_version() and libbpf_minor_version() APIs. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240618183832.2535876-1-andrii@kernel.org
2024-06-18resolve_btfids: Handle presence of .BTF.base sectionAlan Maguire1-0/+8
Now that btf_parse_elf() handles .BTF.base section presence, we need to ensure that resolve_btfids uses .BTF.base when present rather than the vmlinux base BTF passed in via the -B option. Detect .BTF.base section presence and unset the base BTF path to ensure that BTF ELF parsing will do the right thing. Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20240613095014.357981-7-alan.maguire@oracle.com
2024-06-12bpftool: Support dumping kfunc prototypes from BTFDaniel Xu1-0/+55
This patch enables dumping kfunc prototypes from bpftool. This is useful b/c with this patch, end users will no longer have to manually define kfunc prototypes. For the kernel tree, this also means we can optionally drop kfunc prototypes from: tools/testing/selftests/bpf/bpf_kfuncs.h tools/testing/selftests/bpf/bpf_experimental.h Example usage: $ make PAHOLE=/home/dxu/dev/pahole/build/pahole -j30 vmlinux $ ./tools/bpf/bpftool/bpftool btf dump file ./vmlinux format c | rg "__ksym;" | head -3 extern void cgroup_rstat_updated(struct cgroup *cgrp, int cpu) __weak __ksym; extern void cgroup_rstat_flush(struct cgroup *cgrp) __weak __ksym; extern struct bpf_key *bpf_lookup_user_key(u32 serial, u64 flags) __weak __ksym; Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Link: https://lore.kernel.org/r/bf6c08f9263c4bd9d10a717de95199d766a13f61.1718207789.git.dxu@dxuuu.xyz Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-11bpftool: Query only cgroup-related attach typesKenta Tada1-4/+36
When CONFIG_NETKIT=y, bpftool-cgroup shows error even if the cgroup's path is correct: $ bpftool cgroup tree /sys/fs/cgroup CgroupPath ID AttachType AttachFlags Name Error: can't query bpf programs attached to /sys/fs/cgroup: No such device or address >From strace and kernel tracing, I found netkit returned ENXIO and this command failed. I think this AttachType(BPF_NETKIT_PRIMARY) is not relevant to cgroup. bpftool-cgroup should query just only cgroup-related attach types. v2->v3: - removed an unnecessary check v1->v2: - used an array of cgroup attach types Signed-off-by: Kenta Tada <tadakentaso@gmail.com> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20240607111704.6716-1-tadakentaso@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-11Merge tag 'for-netdev' of ↵Jakub Kicinski3-22/+51
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next Daniel Borkmann says: ==================== pull-request: bpf-next 2024-06-06 We've added 54 non-merge commits during the last 10 day(s) which contain a total of 50 files changed, 1887 insertions(+), 527 deletions(-). The main changes are: 1) Add a user space notification mechanism via epoll when a struct_ops object is getting detached/unregistered, from Kui-Feng Lee. 2) Big batch of BPF selftest refactoring for sockmap and BPF congctl tests, from Geliang Tang. 3) Add BTF field (type and string fields, right now) iterator support to libbpf instead of using existing callback-based approaches, from Andrii Nakryiko. 4) Extend BPF selftests for the latter with a new btf_field_iter selftest, from Alan Maguire. 5) Add new kfuncs for a generic, open-coded bits iterator, from Yafang Shao. 6) Fix BPF selftests' kallsyms_find() helper under kernels configured with CONFIG_LTO_CLANG_THIN, from Yonghong Song. 7) Remove a bunch of unused structs in BPF selftests, from David Alan Gilbert. 8) Convert test_sockmap section names into names understood by libbpf so it can deduce program type and attach type, from Jakub Sitnicki. 9) Extend libbpf with the ability to configure log verbosity via LIBBPF_LOG_LEVEL environment variable, from Mykyta Yatsenko. 10) Fix BPF selftests with regards to bpf_cookie and find_vma flakiness in nested VMs, from Song Liu. 11) Extend riscv32/64 JITs to introduce shift/add helpers to generate Zba optimization, from Xiao Wang. 12) Enable BPF programs to declare arrays and struct fields with kptr, bpf_rb_root, and bpf_list_head, from Kui-Feng Lee. * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (54 commits) selftests/bpf: Drop useless arguments of do_test in bpf_tcp_ca selftests/bpf: Use start_test in test_dctcp in bpf_tcp_ca selftests/bpf: Use start_test in test_dctcp_fallback in bpf_tcp_ca selftests/bpf: Add start_test helper in bpf_tcp_ca selftests/bpf: Use connect_to_fd_opts in do_test in bpf_tcp_ca libbpf: Auto-attach struct_ops BPF maps in BPF skeleton selftests/bpf: Add btf_field_iter selftests selftests/bpf: Fix send_signal test with nested CONFIG_PARAVIRT libbpf: Remove callback-based type/string BTF field visitor helpers bpftool: Use BTF field iterator in btfgen libbpf: Make use of BTF field iterator in BTF handling code libbpf: Make use of BTF field iterator in BPF linker code libbpf: Add BTF field iterator selftests/bpf: Ignore .llvm.<hash> suffix in kallsyms_find() selftests/bpf: Fix bpf_cookie and find_vma in nested VM selftests/bpf: Test global bpf_list_head arrays. selftests/bpf: Test global bpf_rb_root arrays and fields in nested struct types. selftests/bpf: Test kptr arrays and kptrs in nested struct fields. bpf: limit the number of levels of a nested struct type. bpf: look into the types of the fields of a struct type recursively. ... ==================== Link: https://lore.kernel.org/r/20240606223146.23020-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-06-06libbpf: Auto-attach struct_ops BPF maps in BPF skeletonMykyta Yatsenko1-4/+32
Similarly to `bpf_program`, support `bpf_map` automatic attachment in `bpf_object__attach_skeleton`. Currently only struct_ops maps could be attached. On bpftool side, code-generate links in skeleton struct for struct_ops maps. Similarly to `bpf_program_skeleton`, set links in `bpf_map_skeleton`. On libbpf side, extend `bpf_map` with new `autoattach` field to support enabling or disabling autoattach functionality, introducing getter/setter for this field. `bpf_object__(attach|detach)_skeleton` is extended with attaching/detaching struct_ops maps logic. Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240605175135.117127-1-yatsenko@meta.com
2024-06-05bpftool: Use BTF field iterator in btfgenAndrii Nakryiko1-10/+6
Switch bpftool's code which is using libbpf-internal btf_type_visit_type_ids() helper to new btf_field_iter functionality. This makes bpftool code simpler, but also unblocks removing libbpf's btf_type_visit_type_ids() helper completely. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Alan Maguire <alan.maguire@oracle.com> Reviewed-by: Quentin Monnet <qmo@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/bpf/20240605001629.4061937-5-andrii@kernel.org
2024-06-03bpftool: Fix typo in MAX_NUM_METRICS macro nameSwan Beaujard1-7/+7
Correct typo in bpftool profiler and change all instances of 'MATRICS' to 'METRICS' in the profiler.bpf.c file. Signed-off-by: Swan Beaujard <beaujardswan@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240602225812.81171-1-beaujardswan@gmail.com
2024-06-01Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski1-1/+1
Cross-merge networking fixes after downstream PR. Conflicts: drivers/net/ethernet/ti/icssg/icssg_classifier.c abd5576b9c57 ("net: ti: icssg-prueth: Add support for ICSSG switch firmware") 56a5cf538c3f ("net: ti: icssg-prueth: Fix start counter for ft1 filter") https://lore.kernel.org/all/20240531123822.3bb7eadf@canb.auug.org.au/ No other adjacent changes. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-05-31bpftool: Change pid_iter.bpf.c to comply with the change of bpf_link_fops.Kui-Feng Lee1-1/+6
To support epoll, a new instance of file_operations, bpf_link_fops_poll, has been added for links that support epoll. The pid_iter.bpf.c checks f_ops for links and other BPF objects. The check should fail for struct_ops links without this patch. Acked-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com> Link: https://lore.kernel.org/r/20240530065946.979330-9-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2024-05-24bpf: Fix potential integer overflow in resolve_btfidsFriedrich Vock1-1/+1
err is a 32-bit integer, but elf_update returns an off_t, which is 64-bit at least on 64-bit platforms. If symbols_patch is called on a binary between 2-4GB in size, the result will be negative when cast to a 32-bit integer, which the code assumes means an error occurred. This can wrongly trigger build failures when building very large kernel images. Fixes: fbbb68de80a4 ("bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object") Signed-off-by: Friedrich Vock <friedrich.vock@gmx.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240514070931.199694-1-friedrich.vock@gmx.de
2024-05-21bpftool: Un-const bpf_func_info to fix it for llvm 17 and newerIvan Babrou1-1/+1
LLVM 17 started treating const structs as constants: * https://github.com/llvm/llvm-project/commit/0b2d5b967d98 Combined with pointer laundering via ptr_to_u64, which takes a const ptr, but in reality treats the underlying memory as mutable, this makes clang always pass zero to btf__type_by_id, which breaks full name resolution. Disassembly before (LLVM 16) and after (LLVM 17): - 8b 75 cc mov -0x34(%rbp),%esi - e8 47 8d 02 00 call 3f5b0 <btf__type_by_id> + 31 f6 xor %esi,%esi + e8 a9 8c 02 00 call 3f510 <btf__type_by_id> It's a bigger project to fix this properly (and a question whether LLVM itself should detect this), but for right now let's just fix bpftool. For more information, see this thread in bpf mailing list: * https://lore.kernel.org/bpf/CABWYdi0ymezpYsQsPv7qzpx2fWuTkoD1-wG1eT-9x-TSREFrQg@mail.gmail.com/T/ Fixes: b662000aff84 ("bpftool: Adding support for BTF program names") Signed-off-by: Ivan Babrou <ivan@cloudflare.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Nick Desaulniers <ndesaulniers@google.com> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/bpf/20240520225149.5517-1-ivan@cloudflare.com
2024-05-18bpftool: Fix make dependencies for vmlinux.hArtem Savkov1-1/+2
With pre-generated vmlinux.h there is no dependency on neither vmlinux nor bootstrap bpftool. Define dependencies separately for both modes. This avoids needless rebuilds in some corner cases. Suggested-by: Jan Stancek <jstancek@redhat.com> Signed-off-by: Artem Savkov <asavkov@redhat.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240513112658.43691-1-asavkov@redhat.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-05-18bpftool: Introduce btf c dump sortingMykyta Yatsenko3-7/+140
Sort bpftool c dump output; aiming to simplify vmlinux.h diffing and forcing more natural type definitions ordering. Definitions are sorted first by their BTF kind ranks, then by their base type name and by their own name. Type ranks Assign ranks to btf kinds (defined in function btf_type_rank) to set next order: 1. Anonymous enums/enums64 2. Named enums/enums64 3. Trivial types typedefs (ints, then floats) 4. Structs/Unions 5. Function prototypes 6. Forward declarations Type rank is set to maximum for unnamed reference types, structs and unions to avoid emitting those types early. They will be emitted as part of the type chain starting with named type. Lexicographical ordering Each type is assigned a sort_name and own_name. sort_name is the resolved name of the final base type for reference types (typedef, pointer, array etc). Sorting by sort_name allows to group typedefs of the same base type. sort_name for non-reference type is the same as own_name. own_name is a direct name of particular type, is used as final sorting step. Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240514131221.20585-1-yatsenko@meta.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-05-07bpftool, selftests/hid/bpf: Fix 29 clang warningsJohn Hubbard1-1/+1
When building either tools/bpf/bpftool, or tools/testing/selftests/hid, (the same Makefile is used for these), clang generates many instances of the following: "clang: warning: -lLLVM-17: 'linker' input unused" Quentin points out that the LLVM version is only required in $(LIBS), not in $(CFLAGS), so the fix is to remove it from CFLAGS. Suggested-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240505230054.13813-1-jhubbard@nvidia.com
2024-04-16bpftool: Address minor issues in bash completionQuentin Monnet1-36/+25
This commit contains a series of clean-ups and fixes for bpftool's bash completion file: - Make sure all local variables are declared as such. - Make sure variables are initialised before being read. - Update ELF section ("maps" -> ".maps") for looking up map names in object files. - Fix call to _init_completion. - Move definition for MAP_TYPE and PROG_TYPE higher up in the scope to avoid defining them multiple times, reuse MAP_TYPE where relevant. - Simplify completion for "duration" keyword in "bpftool prog profile". - Fix completion for "bpftool struct_ops register" and "bpftool link (pin|detach)" where we would repeatedly suggest file names instead of suggesting just one name. - Fix completion for "bpftool iter pin ... map MAP" to account for the "map" keyword. - Add missing "detach" suggestion for "bpftool link". Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240413011427.14402-3-qmo@kernel.org
2024-04-16bpftool: Update documentation where progs/maps can be passed by nameQuentin Monnet4-4/+4
When using references to BPF programs, bpftool supports passing programs by name on the command line. The manual pages for "bpftool prog" and "bpftool map" (for prog_array updates) mention it, but we have a few additional subcommands that support referencing programs by name but do not mention it in their documentation. Let's update the pages for subcommands "btf", "cgroup", and "net". Similarly, we can reference maps by name when passing them to "bpftool prog load", so we update the page for "bpftool prog" as well. Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240413011427.14402-2-qmo@kernel.org
2024-04-12bpftool: Fix typo in error messageThorsten Blum1-1/+1
s/at at/at a/ Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240411164258.533063-3-thorsten.blum@toblux.com
2024-04-11bpftool: Add link dump support for BPF_LINK_TYPE_SOCKMAPYonghong Song1-0/+9
An example output looks like: $ bpftool link 1776: sk_skb prog 49730 map_id 0 attach_type sk_skb_verdict pids test_progs(8424) 1777: sk_skb prog 49755 map_id 0 attach_type sk_skb_stream_verdict pids test_progs(8424) 1778: sk_msg prog 49770 map_id 8208 attach_type sk_msg_verdict pids test_progs(8424) Reviewed-by: John Fastabend <john.fastabend@gmail.com> Reviewed-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20240410043537.3737928-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-04-05bpftool: Mount bpffs on provided dir instead of parent dirSahil Siddiq5-16/+92
When pinning programs/objects under PATH (eg: during "bpftool prog loadall") the bpffs is mounted on the parent dir of PATH in the following situations: - the given dir exists but it is not bpffs. - the given dir doesn't exist and the parent dir is not bpffs. Mounting on the parent dir can also have the unintentional side- effect of hiding other files located under the parent dir. If the given dir exists but is not bpffs, then the bpffs should be mounted on the given dir and not its parent dir. Similarly, if the given dir doesn't exist and its parent dir is not bpffs, then the given dir should be created and the bpffs should be mounted on this new dir. Fixes: 2a36c26fe3b8 ("bpftool: Support bpffs mountpoint as pin path for prog loadall") Signed-off-by: Sahil Siddiq <icegambit91@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/2da44d24-74ae-a564-1764-afccf395eeec@isovalent.com/T/#t Link: https://lore.kernel.org/bpf/20240404192219.52373-1-icegambit91@gmail.com Closes: https://github.com/libbpf/bpftool/issues/100 Changes since v1: - Split "mount_bpffs_for_pin" into two functions. This is done to improve maintainability and readability. Changes since v2: - mount_bpffs_for_pin: rename to "create_and_mount_bpffs_dir". - mount_bpffs_given_file: rename to "mount_bpffs_given_file". - create_and_mount_bpffs_dir: - introduce "dir_exists" boolean. - remove new dir if "mnt_fs" fails. - improve error handling and error messages. Changes since v3: - Rectify function name. - Improve error messages and formatting. - mount_bpffs_for_file: - Check if dir exists before block_mount check. Changes since v4: - Use strdup instead of strcpy. - create_and_mount_bpffs_dir: - Use S_IRWXU instead of 0700. - Improve error handling and formatting.
2024-04-02bpftool: Use __typeof__() instead of typeof() in BPF skeletonAndrii Nakryiko1-2/+2
When generated BPF skeleton header is included in C++ code base, some compiler setups will emit warning about using language extensions due to typeof() usage, resulting in something like: error: extension used [-Werror,-Wlanguage-extension-token] obj->struct_ops.empty_tcp_ca = (typeof(obj->struct_ops.empty_tcp_ca)) ^ It looks like __typeof__() is a preferred way to do typeof() with better C++ compatibility behavior, so switch to that. With __typeof__() we get no such warning. Fixes: c2a0257c1edf ("bpftool: Cast pointers for shadow types explicitly.") Fixes: 00389c58ffe9 ("bpftool: Add support for subskeletons") Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Kui-Feng Lee <thinker.li@gmail.com> Acked-by: Quentin Monnet <qmo@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20240401170713.2081368-1-andrii@kernel.org
2024-04-02bpftool: Clean-up typos, punctuation, list formatting in docsRameez Rehman3-40/+35
Improve the formatting of the attach flags for cgroup programs in the relevant man page, and fix typos ("can be on of", "an userspace inet socket") when introducing that list. Also fix a couple of other trivial issues in docs. [ Quentin: Fixed trival issues in bpftool-gen.rst and bpftool-iter.rst ] Signed-off-by: Rameez Rehman <rameezrehman408@hotmail.com> Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240331200346.29118-4-qmo@kernel.org
2024-04-02bpftool: Remove useless emphasis on command description in man pagesRameez Rehman11-61/+61
As it turns out, the terms in definition lists in the rST file are already rendered with bold-ish formatting when generating the man pages; all double-star sequences we have in the commands for the command description are unnecessary, and can be removed to make the documentation easier to read. The rST files were automatically processed with: sed -i '/DESCRIPTION/,/OPTIONS/ { /^\*/ s/\*\*//g }' b*.rst Signed-off-by: Rameez Rehman <rameezrehman408@hotmail.com> Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240331200346.29118-3-qmo@kernel.org
2024-04-02bpftool: Use simpler indentation in source rST for documentationRameez Rehman14-991/+908
The rST manual pages for bpftool would use a mix of tabs and spaces for indentation. While this is the norm in C code, this is rather unusual for rST documents, and over time we've seen many contributors use a wrong level of indentation for documentation update. Let's fix bpftool's indentation in docs once and for all: - Let's use spaces, that are more common in rST files. - Remove one level of indentation for the synopsis, the command description, and the "see also" section. As a result, all sections start with the same indentation level in the generated man page. - Rewrap the paragraphs after the changes. There is no content change in this patch, only indentation and rewrapping changes. The wrapping in the generated source files for the manual pages is changed, but the pages displayed with "man" remain the same, apart from the adjusted indentation level on relevant sections. [ Quentin: rebased on bpf-next, removed indent level for command description and options, updated synopsis, command summary, and "see also" sections. ] Signed-off-by: Rameez Rehman <rameezrehman408@hotmail.com> Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240331200346.29118-2-qmo@kernel.org
2024-03-29bpf: improve error message for unsupported helperMykyta Yatsenko1-1/+2
BPF verifier emits "unknown func" message when given BPF program type does not support BPF helper. This message may be confusing for users, as important context that helper is unknown only to current program type is not provided. This patch changes message to "program of this type cannot use helper " and aligns dependent code in libbpf and tests. Any suggestions on improving/changing this message are welcome. Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20240325152210.377548-1-yatsenko@meta.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-03-29Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski1-1/+1
Cross-merge networking fixes after downstream PR. No conflicts, or adjacent changes. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-21bpftool: Clean up HOST_CFLAGS, HOST_LDFLAGS for bootstrap bpftoolQuentin Monnet1-4/+5
Bpftool's Makefile uses $(HOST_CFLAGS) to build the bootstrap version of bpftool, in order to pick the flags for the host (where we run the bootstrap version) and not for the target system (where we plan to run the full bpftool binary). But we pass too much information through this variable. In particular, we set HOST_CFLAGS by copying most of the $(CFLAGS); but we do this after the feature detection for bpftool, which means that $(CFLAGS), hence $(HOST_CFLAGS), contain all macro definitions for using the different optional features. For example, -DHAVE_LLVM_SUPPORT may be passed to the $(HOST_CFLAGS), even though the LLVM disassembler is not used in the bootstrap version, and the related library may even be missing for the host architecture. A similar thing happens with the $(LDFLAGS), that we use unchanged for linking the bootstrap version even though they may contains flags to link against additional libraries. To address the $(HOST_CFLAGS) issue, we move the definition of $(HOST_CFLAGS) earlier in the Makefile, before the $(CFLAGS) update resulting from the feature probing - none of which being relevant to the bootstrap version. To clean up the $(LDFLAGS) for the bootstrap version, we introduce a dedicated $(HOST_LDFLAGS) variable that we base on $(LDFLAGS), before the feature probing as well. On my setup, the following macro and libraries are removed from the compiler invocation to build bpftool after this patch: -DUSE_LIBCAP -DHAVE_LLVM_SUPPORT -I/usr/lib/llvm-17/include -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -lLLVM-17 -L/usr/lib/llvm-17/lib Another advantage of cleaning up these flags is that displaying available features with "bpftool version" becomes more accurate for the bootstrap bpftool, and no longer reflects the features detected (and available only) for the final binary. Cc: Jean-Philippe Brucker <jean-philippe@linaro.org> Signed-off-by: Quentin Monnet <qmo@kernel.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Message-ID: <20240320014103.45641-1-qmo@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-03-20bpftool: Remove unnecessary source files from bootstrap versionQuentin Monnet1-4/+1
Commit d510296d331a ("bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command.") added new files to the list of objects to compile in order to build the bootstrap version of bpftool. As far as I can tell, these objects are unnecessary and were added by mistake; maybe a draft version intended to add support for loading loader programs from the bootstrap version. Anyway, we can remove these object files from the list to make the bootstrap bpftool binary a tad smaller and faster to build. Fixes: d510296d331a ("bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command.") Signed-off-by: Quentin Monnet <qmo@kernel.org> Message-ID: <20240320013457.44808-1-qmo@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-03-20bpftool: Enable libbpf logs when loading pid_iter in debug modeQuentin Monnet1-7/+12
When trying to load the pid_iter BPF program used to iterate over the PIDs of the processes holding file descriptors to BPF links, we would unconditionally silence libbpf in order to keep the output clean if the kernel does not support iterators and loading fails. Although this is the desirable behaviour in most cases, this may hide bugs in the pid_iter program that prevent it from loading, and it makes it hard to debug such load failures, even in "debug" mode. Instead, it makes more sense to print libbpf's logs when we pass the -d|--debug flag to bpftool, so that users get the logs to investigate failures without having to edit bpftool's source code. Signed-off-by: Quentin Monnet <qmo@kernel.org> Message-ID: <20240320012241.42991-1-qmo@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-03-16libbpf, selftests/bpf: Adjust libbpf, bpftool, selftests to match LLVMAlexei Starovoitov1-1/+1
The selftests use to tell LLVM about special pointers. For LLVM there is nothing "arena" about them. They are simply pointers in a different address space. Hence LLVM diff https://github.com/llvm/llvm-project/pull/85161 renamed: . macro __BPF_FEATURE_ARENA_CAST -> __BPF_FEATURE_ADDR_SPACE_CAST . global variables in __attribute__((address_space(N))) are now placed in section named ".addr_space.N" instead of ".arena.N". Adjust libbpf, bpftool, and selftests to match LLVM. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Stanislav Fomichev <sdf@google.com> Link: https://lore.kernel.org/bpf/20240315021834.62988-3-alexei.starovoitov@gmail.com
2024-03-14bpftool: Fix missing pids during link showYonghong Song1-2/+2
Current 'bpftool link' command does not show pids, e.g., $ tools/build/bpftool/bpftool link ... 4: tracing prog 23 prog_type lsm attach_type lsm_mac target_obj_id 1 target_btf_id 31320 Hack the following change to enable normal libbpf debug output, --- a/tools/bpf/bpftool/pids.c +++ b/tools/bpf/bpftool/pids.c @@ -121,9 +121,9 @@ int build_obj_refs_table(struct hashmap **map, enum bpf_obj_type type) /* we don't want output polluted with libbpf errors if bpf_iter is not * supported */ - default_print = libbpf_set_print(libbpf_print_none); + /* default_print = libbpf_set_print(libbpf_print_none); */ err = pid_iter_bpf__load(skel); - libbpf_set_print(default_print); + /* libbpf_set_print(default_print); */ Rerun the above bpftool command: $ tools/build/bpftool/bpftool link libbpf: prog 'iter': BPF program load failed: Permission denied libbpf: prog 'iter': -- BEGIN PROG LOAD LOG -- 0: R1=ctx() R10=fp0 ; struct task_struct *task = ctx->task; @ pid_iter.bpf.c:69 0: (79) r6 = *(u64 *)(r1 +8) ; R1=ctx() R6_w=ptr_or_null_task_struct(id=1) ; struct file *file = ctx->file; @ pid_iter.bpf.c:68 ... ; struct bpf_link *link = (struct bpf_link *) file->private_data; @ pid_iter.bpf.c:103 80: (79) r3 = *(u64 *)(r8 +432) ; R3_w=scalar() R8=ptr_file() ; if (link->type == bpf_core_enum_value(enum bpf_link_type___local, @ pid_iter.bpf.c:105 81: (61) r1 = *(u32 *)(r3 +12) R3 invalid mem access 'scalar' processed 39 insns (limit 1000000) max_states_per_insn 0 total_states 3 peak_states 3 mark_read 2 -- END PROG LOAD LOG -- libbpf: prog 'iter': failed to load: -13 ... The 'file->private_data' returns a 'void' type and this caused subsequent 'link->type' (insn #81) failed in verification. To fix the issue, restore the previous BPF_CORE_READ so old kernels can also work. With this patch, the 'bpftool link' runs successfully with 'pids'. $ tools/build/bpftool/bpftool link ... 4: tracing prog 23 prog_type lsm attach_type lsm_mac target_obj_id 1 target_btf_id 31320 pids systemd(1) Fixes: 44ba7b30e84f ("bpftool: Use a local copy of BPF_LINK_TYPE_PERF_EVENT in pid_iter.bpf.c") Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Quentin Monnet <quentin@isovalent.com> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20240312023249.3776718-1-yonghong.song@linux.dev
2024-03-14bpftool: Cast pointers for shadow types explicitly.Kui-Feng Lee1-1/+2
According to a report, skeletons fail to assign shadow pointers when being compiled with C++ programs. Unlike C doing implicit casting for void pointers, C++ requires an explicit casting. To support C++, we do explicit casting for each shadow pointer. Also add struct_ops_module.skel.h to test_cpp to validate C++ compilation as part of BPF selftests. Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20240312013726.1780720-1-thinker.li@gmail.com
2024-03-12libbpf: Recognize __arena global variables.Andrii Nakryiko1-0/+13
LLVM automatically places __arena variables into ".arena.1" ELF section. In order to use such global variables bpf program must include definition of arena map in ".maps" section, like: struct { __uint(type, BPF_MAP_TYPE_ARENA); __uint(map_flags, BPF_F_MMAPABLE); __uint(max_entries, 1000); /* number of pages */ __ulong(map_extra, 2ull << 44); /* start of mmap() region */ } arena SEC(".maps"); libbpf recognizes both uses of arena and creates single `struct bpf_map *` instance in libbpf APIs. ".arena.1" ELF section data is used as initial data image, which is exposed through skeleton and bpf_map__initial_value() to the user, if they need to tune it before the load phase. During load phase, this initial image is copied over into mmap()'ed region corresponding to arena, and discarded. Few small checks here and there had to be added to make sure this approach works with bpf_map__initial_value(), mostly due to hard-coded assumption that map->mmaped is set up with mmap() syscall and should be munmap()'ed. For arena, .arena.1 can be (much) smaller than maximum arena size, so this smaller data size has to be tracked separately. Given it is enforced that there is only one arena for entire bpf_object instance, we just keep it in a separate field. This can be generalized if necessary later. All global variables from ".arena.1" section are accessible from user space via skel->arena->name_of_var. For bss/data/rodata the skeleton/libbpf perform the following sequence: 1. addr = mmap(MAP_ANONYMOUS) 2. user space optionally modifies global vars 3. map_fd = bpf_create_map() 4. bpf_update_map_elem(map_fd, addr) // to store values into the kernel 5. mmap(addr, MAP_FIXED, map_fd) after step 5 user spaces see the values it wrote at step 2 at the same addresses arena doesn't support update_map_elem. Hence skeleton/libbpf do: 1. addr = malloc(sizeof SEC ".arena.1") 2. user space optionally modifies global vars 3. map_fd = bpf_create_map(MAP_TYPE_ARENA) 4. real_addr = mmap(map->map_extra, MAP_SHARED | MAP_FIXED, map_fd) 5. memcpy(real_addr, addr) // this will fault-in and allocate pages At the end look and feel of global data vs __arena global data is the same from bpf prog pov. Another complication is: struct { __uint(type, BPF_MAP_TYPE_ARENA); } arena SEC(".maps"); int __arena foo; int bar; ptr1 = &foo; // relocation against ".arena.1" section ptr2 = &arena; // relocation against ".maps" section ptr3 = &bar; // relocation against ".bss" section Fo the kernel ptr1 and ptr2 has point to the same arena's map_fd while ptr3 points to a different global array's map_fd. For the verifier: ptr1->type == unknown_scalar ptr2->type == const_ptr_to_map ptr3->type == ptr_to_map_value After verification, from JIT pov all 3 ptr-s are normal ld_imm64 insns. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20240308010812.89848-11-alexei.starovoitov@gmail.com
generated by cgit v1.2.3 (git 2.39.0) at 2024-10-21 06:45:04 +0300