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2020-09-29bpf: Add bpf_snprintf_btf helperAlan Maguire1-0/+2
A helper is added to support tracing kernel type information in BPF using the BPF Type Format (BTF). Its signature is long bpf_snprintf_btf(char *str, u32 str_size, struct btf_ptr *ptr, u32 btf_ptr_size, u64 flags); struct btf_ptr * specifies - a pointer to the data to be traced - the BTF id of the type of data pointed to - a flags field is provided for future use; these flags are not to be confused with the BTF_F_* flags below that control how the btf_ptr is displayed; the flags member of the struct btf_ptr may be used to disambiguate types in kernel versus module BTF, etc; the main distinction is the flags relate to the type and information needed in identifying it; not how it is displayed. For example a BPF program with a struct sk_buff *skb could do the following: static struct btf_ptr b = { }; b.ptr = skb; b.type_id = __builtin_btf_type_id(struct sk_buff, 1); bpf_snprintf_btf(str, sizeof(str), &b, sizeof(b), 0, 0); Default output looks like this: (struct sk_buff){ .transport_header = (__u16)65535, .mac_header = (__u16)65535, .end = (sk_buff_data_t)192, .head = (unsigned char *)0x000000007524fd8b, .data = (unsigned char *)0x000000007524fd8b, .truesize = (unsigned int)768, .users = (refcount_t){ .refs = (atomic_t){ .counter = (int)1, }, }, } Flags modifying display are as follows: - BTF_F_COMPACT: no formatting around type information - BTF_F_NONAME: no struct/union member names/types - BTF_F_PTR_RAW: show raw (unobfuscated) pointer values; equivalent to %px. - BTF_F_ZERO: show zero-valued struct/union members; they are not displayed by default Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/1601292670-1616-4-git-send-email-alan.maguire@oracle.com
2020-08-26bpf: Add d_path helperJiri Olsa1-0/+2
Adding d_path helper function that returns full path for given 'struct path' object, which needs to be the kernel BTF 'path' object. The path is returned in buffer provided 'buf' of size 'sz' and is zero terminated. bpf_d_path(&file->f_path, buf, size); The helper calls directly d_path function, so there's only limited set of function it can be called from. Adding just very modest set for the start. Updating also bpf.h tools uapi header and adding 'path' to bpf_helpers_doc.py script. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: KP Singh <kpsingh@google.com> Link: https://lore.kernel.org/bpf/20200825192124.710397-11-jolsa@kernel.org
2020-07-18bpf: Introduce SK_LOOKUP program type with a dedicated attach pointJakub Sitnicki1-1/+8
Add a new program type BPF_PROG_TYPE_SK_LOOKUP with a dedicated attach type BPF_SK_LOOKUP. The new program kind is to be invoked by the transport layer when looking up a listening socket for a new connection request for connection oriented protocols, or when looking up an unconnected socket for a packet for connection-less protocols. When called, SK_LOOKUP BPF program can select a socket that will receive the packet. This serves as a mechanism to overcome the limits of what bind() API allows to express. Two use-cases driving this work are: (1) steer packets destined to an IP range, on fixed port to a socket 192.0.2.0/24, port 80 -> NGINX socket (2) steer packets destined to an IP address, on any port to a socket 198.51.100.1, any port -> L7 proxy socket In its run-time context program receives information about the packet that triggered the socket lookup. Namely IP version, L4 protocol identifier, and address 4-tuple. Context can be further extended to include ingress interface identifier. To select a socket BPF program fetches it from a map holding socket references, like SOCKMAP or SOCKHASH, and calls bpf_sk_assign(ctx, sk, ...) helper to record the selection. Transport layer then uses the selected socket as a result of socket lookup. In its basic form, SK_LOOKUP acts as a filter and hence must return either SK_PASS or SK_DROP. If the program returns with SK_PASS, transport should look for a socket to receive the packet, or use the one selected by the program if available, while SK_DROP informs the transport layer that the lookup should fail. This patch only enables the user to attach an SK_LOOKUP program to a network namespace. Subsequent patches hook it up to run on local delivery path in ipv4 and ipv6 stacks. Suggested-by: Marek Majkowski <marek@cloudflare.com> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200717103536.397595-3-jakub@cloudflare.com
2020-07-01bpf: Introduce helper bpf_get_task_stack()Song Liu1-0/+2
Introduce helper bpf_get_task_stack(), which dumps stack trace of given task. This is different to bpf_get_stack(), which gets stack track of current task. One potential use case of bpf_get_task_stack() is to call it from bpf_iter__task and dump all /proc/<pid>/stack to a seq_file. bpf_get_task_stack() uses stack_trace_save_tsk() instead of get_perf_callchain() for kernel stack. The benefit of this choice is that stack_trace_save_tsk() doesn't require changes in arch/. The downside of using stack_trace_save_tsk() is that stack_trace_save_tsk() dumps the stack trace to unsigned long array. For 32-bit systems, we need to translate it to u64 array. Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200630062846.664389-3-songliubraving@fb.com
2020-06-25bpf: Add bpf_skc_to_udp6_sock() helperYonghong Song1-0/+2
The helper is used in tracing programs to cast a socket pointer to a udp6_sock pointer. The return value could be NULL if the casting is illegal. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Cc: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/bpf/20200623230815.3988481-1-yhs@fb.com
2020-06-25bpf: Add bpf_skc_to_{tcp, tcp_timewait, tcp_request}_sock() helpersYonghong Song1-0/+6
Three more helpers are added to cast a sock_common pointer to an tcp_sock, tcp_timewait_sock or a tcp_request_sock for tracing programs. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200623230811.3988277-1-yhs@fb.com
2020-06-25bpf: Add bpf_skc_to_tcp6_sock() helperYonghong Song1-0/+2
The helper is used in tracing programs to cast a socket pointer to a tcp6_sock pointer. The return value could be NULL if the casting is illegal. A new helper return type RET_PTR_TO_BTF_ID_OR_NULL is added so the verifier is able to deduce proper return types for the helper. Different from the previous BTF_ID based helpers, the bpf_skc_to_tcp6_sock() argument can be several possible btf_ids. More specifically, all possible socket data structures with sock_common appearing in the first in the memory layout. This patch only added socket types related to tcp and udp. All possible argument btf_id and return value btf_id for helper bpf_skc_to_tcp6_sock() are pre-calculcated and cached. In the future, it is even possible to precompute these btf_id's at kernel build time. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200623230809.3988195-1-yhs@fb.com
2020-05-11bpf: Minor fixes to BPF helpers documentationQuentin Monnet1-0/+6
Minor improvements to the documentation for BPF helpers: * Fix formatting for the description of "bpf_socket" for bpf_getsockopt() and bpf_setsockopt(), thus suppressing two warnings from rst2man about "Unexpected indentation". * Fix formatting for return values for bpf_sk_assign() and seq_file helpers. * Fix and harmonise formatting, in particular for function/struct names. * Remove blank lines before "Return:" sections. * Replace tabs found in the middle of text lines. * Fix typos. * Add a note to the footer (in Python script) about "bpftool feature probe", including for listing features available to unprivileged users, and add a reference to bpftool man page. Thanks to Florian for reporting two typos (duplicated words). Signed-off-by: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200511161536.29853-4-quentin@isovalent.com
2020-05-10bpf: Add bpf_seq_printf and bpf_seq_write helpersYonghong Song1-0/+2
Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-03-13bpf_helpers_doc.py: Fix warning when compiling bpftoolCarlos Neira1-0/+1
When compiling bpftool the following warning is found: "declaration of 'struct bpf_pidns_info' will not be visible outside of this function." This patch adds struct bpf_pidns_info to type_fwds array to fix this. Fixes: b4490c5c4e02 ("bpf: Added new helper bpf_get_ns_current_pid_tgid") Signed-off-by: Carlos Neira <cneirabustos@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200313154650.13366-1-cneirabustos@gmail.com
2020-03-13bpf: Added new helper bpf_get_ns_current_pid_tgidCarlos Neira1-0/+1
New bpf helper bpf_get_ns_current_pid_tgid, This helper will return pid and tgid from current task which namespace matches dev_t and inode number provided, this will allows us to instrument a process inside a container. Signed-off-by: Carlos Neira <cneirabustos@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200304204157.58695-3-cneirabustos@gmail.com
2020-02-26scripts/bpf: Switch to more portable python3 shebangScott Branden1-1/+1
Change "/usr/bin/python3" to "/usr/bin/env python3" for more portable solution in bpf_helpers_doc.py. Signed-off-by: Scott Branden <scott.branden@broadcom.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200225205426.6975-1-scott.branden@broadcom.com
2020-01-14libbpf: Clean up bpf_helper_defs.h generation outputAndrii Nakryiko1-2/+0
bpf_helpers_doc.py script, used to generate bpf_helper_defs.h, unconditionally emits one informational message to stderr. Remove it and preserve stderr to contain only relevant errors. Also make sure script invocations command is muted by default in libbpf's Makefile. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200113073143.1779940-3-andriin@fb.com
2019-10-21scripts/bpf: Print an error when known types list needs updatingJakub Sitnicki1-2/+2
Don't generate a broken bpf_helper_defs.h header if the helper script needs updating because it doesn't recognize a newly added type. Instead print an error that explains why the build is failing, clean up the partially generated header and stop. v1->v2: - Switched from temporary file to .DELETE_ON_ERROR. Fixes: 456a513bb5d4 ("scripts/bpf: Emit an #error directive known types list needs updating") Suggested-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20191020112344.19395-1-jakub@cloudflare.com
2019-10-16scripts/bpf: Emit an #error directive known types list needs updatingJakub Sitnicki1-1/+1
Make the compiler report a clear error when bpf_helpers_doc.py needs updating rather than rely on the fact that Clang fails to compile English: ../../../lib/bpf/bpf_helper_defs.h:2707:1: error: unknown type name 'Unrecognized' Unrecognized type 'struct bpf_inet_lookup', please add it to known types! Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20191016085811.11700-1-jakub@cloudflare.com
2019-10-10scripts/bpf: Fix xdp_md forward declaration typoAndrii Nakryiko1-1/+1
Fix typo in struct xpd_md, generated from bpf_helpers_doc.py, which is causing compilation warnings for programs using bpf_helpers.h Fixes: 7a387bed47f7 ("scripts/bpf: teach bpf_helpers_doc.py to dump BPF helper definitions") Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191010042534.290562-1-andriin@fb.com
2019-10-07scripts/bpf: teach bpf_helpers_doc.py to dump BPF helper definitionsAndrii Nakryiko1-1/+154
Enhance scripts/bpf_helpers_doc.py to emit C header with BPF helper definitions (to be included from libbpf's bpf_helpers.h). Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-05-13bpf: fix script for generating man page on BPF helpersQuentin Monnet1-4/+4
The script broke on parsing function prototype for bpf_strtoul(). This is because the last argument for the function is a pointer to an "unsigned long". The current version of the script only accepts "const" and "struct", but not "unsigned", at the beginning of argument types made of several words. One solution could be to add "unsigned" to the list, but the issue could come up again in the future (what about "long int"?). It turns out we do not need to have such restrictions on the words: so let's simply accept any series of words instead. Reported-by: Yonghong Song <yhs@fb.com> Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com> Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-05-17bpf: change eBPF helper doc parsing script to allow for smaller indentQuentin Monnet1-4/+4
Documentation for eBPF helpers can be parsed from bpf.h and eventually turned into a man page. Commit 6f96674dbd8c ("bpf: relax constraints on formatting for eBPF helper documentation") changed the script used to parse it, in order to allow for different indent style and to ease the work for writing documentation for future helpers. The script currently considers that the first tab can be replaced by 6 to 8 spaces. But the documentation for bpf_fib_lookup() uses a mix of tabs (for the "Description" part) and of spaces ("Return" part), and only has 5 space long indent for the latter. We probably do not want to change the values accepted by the script each time a new helper gets a new indent style. However, it is worth noting that with those 5 spaces, the "Description" and "Return" part *look* aligned in the generated patch and in `git show`, so it is likely other helper authors will use the same length. Therefore, allow for helper documentation to use 5 spaces only for the first indent level. Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-05-02bpf: relax constraints on formatting for eBPF helper documentationQuentin Monnet1-7/+7
The Python script used to parse and extract eBPF helpers documentation from include/uapi/linux/bpf.h expects a very specific formatting for the descriptions (single dot represents a space, '>' stands for a tab): /* ... *.int bpf_helper(list of arguments) *.> Description *.> > Start of description *.> > Another line of description *.> > And yet another line of description *.> Return *.> > 0 on success, or a negative error in case of failure ... */ This is too strict, and painful for developers who wants to add documentation for new helpers. Worse, it is extremely difficult to check that the formatting is correct during reviews. Change the format expected by the script and make it more flexible. The script now works whether or not the initial space (right after the star) is present, and accepts both tabs and white spaces (or a combination of both) for indenting description sections and contents. Concretely, something like the following would now be supported: /* ... *int bpf_helper(list of arguments) *......Description *.> > Start of description... *> > Another line of description *..............And yet another line of description *> Return *.> ........0 on success, or a negative error in case of failure ... */ While at it, remove unnecessary carets from each regex used with match() in the script. They are redundant, as match() tries to match from the beginning of the string by default. v2: Remove unnecessary caret when a regex is used with match(). Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-27bpf: add script and prepare bpf.h for new helpers documentationQuentin Monnet1-0/+421
Remove previous "overview" of eBPF helpers from user bpf.h header. Replace it by a comment explaining how to process the new documentation (to come in following patches) with a Python script to produce RST, then man page documentation. Also add the aforementioned Python script under scripts/. It is used to process include/uapi/linux/bpf.h and to extract helper descriptions, to turn it into a RST document that can further be processed with rst2man to produce a man page. The script takes one "--filename <path/to/file>" option. If the script is launched from scripts/ in the kernel root directory, it should be able to find the location of the header to parse, and "--filename <path/to/file>" is then optional. If it cannot find the file, then the option becomes mandatory. RST-formatted documentation is printed to standard output. Typical workflow for producing the final man page would be: $ ./scripts/bpf_helpers_doc.py \ --filename include/uapi/linux/bpf.h > /tmp/bpf-helpers.rst $ rst2man /tmp/bpf-helpers.rst > /tmp/bpf-helpers.7 $ man /tmp/bpf-helpers.7 Note that the tool kernel-doc cannot be used to document eBPF helpers, whose signatures are not available directly in the header files (pre-processor directives are used to produce them at the beginning of the compilation process). v4: - Also remove overviews for newly added bpf_xdp_adjust_tail() and bpf_skb_get_xfrm_state(). - Remove vague statement about what helpers are restricted to GPL programs in "LICENSE" section for man page footer. - Replace license boilerplate with SPDX tag for Python script. v3: - Change license for man page. - Remove "for safety reasons" from man page header text. - Change "packets metadata" to "packets" in man page header text. - Move and fix comment on helpers introducing no overhead. - Remove "NOTES" section from man page footer. - Add "LICENSE" section to man page footer. - Edit description of file include/uapi/linux/bpf.h in man page footer. Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>