Commit Graph

205 Commits

Author SHA1 Message Date
Linus Torvalds 8c1318e438 lsm/stable-6.4 PR 20230428
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Merge tag 'lsm-pr-20230428' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

Pull lsm fix from Paul Moore:
 "A single Documentation/LSM fix to update the LSM hook documentation
  references from lsm_hooks.h to security.c"

* tag 'lsm-pr-20230428' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
  lsm: move hook comments docs to security/security.c
2023-04-29 10:17:05 -07:00
Randy Dunlap 6d2ed65318 lsm: move hook comments docs to security/security.c
Fix one kernel-doc warning, but invesigating that led to other
kernel-doc movement (lsm_hooks.h to security.c) that needs to be
fixed also.

include/linux/lsm_hooks.h:1: warning: no structured comments found

Fixes: e261301c85 ("lsm: move the remaining LSM hook comments to security/security.c")
Fixes: 1cd2aca64a ("lsm: move the io_uring hook comments to security/security.c")
Fixes: 452b670c72 ("lsm: move the perf hook comments to security/security.c")
Fixes: 55e853201a ("lsm: move the bpf hook comments to security/security.c")
Fixes: b14faf9c94 ("lsm: move the audit hook comments to security/security.c")
Fixes: 1427ddbe5c ("lsm: move the binder hook comments to security/security.c")
Fixes: 43fad28218 ("lsm: move the sysv hook comments to security/security.c")
Fixes: ecc419a445 ("lsm: move the key hook comments to security/security.c")
Fixes: 742b99456e ("lsm: move the xfrm hook comments to security/security.c")
Fixes: ac318aed54 ("lsm: move the Infiniband hook comments to security/security.c")
Fixes: 4a49f592e9 ("lsm: move the SCTP hook comments to security/security.c")
Fixes: 6b6bbe8c02 ("lsm: move the socket hook comments to security/security.c")
Fixes: 2c2442fd46 ("lsm: move the AF_UNIX hook comments to security/security.c")
Fixes: 2bcf51bf2f ("lsm: move the netlink hook comments to security/security.c")
Fixes: 130c53bfee ("lsm: move the task hook comments to security/security.c")
Fixes: a0fd6480de ("lsm: move the file hook comments to security/security.c")
Fixes: 9348944b77 ("lsm: move the kernfs hook comments to security/security.c")
Fixes: 916e32584d ("lsm: move the inode hook comments to security/security.c")
Fixes: 08526a902c ("lsm: move the filesystem hook comments to security/security.c")
Fixes: 36819f1855 ("lsm: move the fs_context hook comments to security/security.c")
Fixes: 1661372c91 ("lsm: move the program execution hook comments to security/security.c")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-security-module@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: KP Singh <kpsingh@kernel.org>
Cc: bpf@vger.kernel.org
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-04-28 11:58:34 -04:00
David Vernet 530474e6d0 bpf,docs: Remove KF_KPTR_GET from documentation
A prior patch removed KF_KPTR_GET from the kernel. Now that it's no
longer accessible to kfunc authors, this patch removes it from the BPF
kfunc documentation.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230416084928.326135-4-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-04-16 08:51:24 -07:00
Jakub Kicinski c2865b1122 bpf-next-for-netdev
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Daniel Borkmann says:

====================
pull-request: bpf-next 2023-04-13

We've added 260 non-merge commits during the last 36 day(s) which contain
a total of 356 files changed, 21786 insertions(+), 11275 deletions(-).

The main changes are:

1) Rework BPF verifier log behavior and implement it as a rotating log
   by default with the option to retain old-style fixed log behavior,
   from Andrii Nakryiko.

2) Adds support for using {FOU,GUE} encap with an ipip device operating
   in collect_md mode and add a set of BPF kfuncs for controlling encap
   params, from Christian Ehrig.

3) Allow BPF programs to detect at load time whether a particular kfunc
   exists or not, and also add support for this in light skeleton,
   from Alexei Starovoitov.

4) Optimize hashmap lookups when key size is multiple of 4,
   from Anton Protopopov.

5) Enable RCU semantics for task BPF kptrs and allow referenced kptr
   tasks to be stored in BPF maps, from David Vernet.

6) Add support for stashing local BPF kptr into a map value via
   bpf_kptr_xchg(). This is useful e.g. for rbtree node creation
   for new cgroups, from Dave Marchevsky.

7) Fix BTF handling of is_int_ptr to skip modifiers to work around
   tracing issues where a program cannot be attached, from Feng Zhou.

8) Migrate a big portion of test_verifier unit tests over to
   test_progs -a verifier_* via inline asm to ease {read,debug}ability,
   from Eduard Zingerman.

9) Several updates to the instruction-set.rst documentation
   which is subject to future IETF standardization
   (https://lwn.net/Articles/926882/), from Dave Thaler.

10) Fix BPF verifier in the __reg_bound_offset's 64->32 tnum sub-register
    known bits information propagation, from Daniel Borkmann.

11) Add skb bitfield compaction work related to BPF with the overall goal
    to make more of the sk_buff bits optional, from Jakub Kicinski.

12) BPF selftest cleanups for build id extraction which stand on its own
    from the upcoming integration work of build id into struct file object,
    from Jiri Olsa.

13) Add fixes and optimizations for xsk descriptor validation and several
    selftest improvements for xsk sockets, from Kal Conley.

14) Add BPF links for struct_ops and enable switching implementations
    of BPF TCP cong-ctls under a given name by replacing backing
    struct_ops map, from Kui-Feng Lee.

15) Remove a misleading BPF verifier env->bypass_spec_v1 check on variable
    offset stack read as earlier Spectre checks cover this,
    from Luis Gerhorst.

16) Fix issues in copy_from_user_nofault() for BPF and other tracers
    to resemble copy_from_user_nmi() from safety PoV, from Florian Lehner
    and Alexei Starovoitov.

17) Add --json-summary option to test_progs in order for CI tooling to
    ease parsing of test results, from Manu Bretelle.

18) Batch of improvements and refactoring to prep for upcoming
    bpf_local_storage conversion to bpf_mem_cache_{alloc,free} allocator,
    from Martin KaFai Lau.

19) Improve bpftool's visual program dump which produces the control
    flow graph in a DOT format by adding C source inline annotations,
    from Quentin Monnet.

20) Fix attaching fentry/fexit/fmod_ret/lsm to modules by extracting
    the module name from BTF of the target and searching kallsyms of
    the correct module, from Viktor Malik.

21) Improve BPF verifier handling of '<const> <cond> <non_const>'
    to better detect whether in particular jmp32 branches are taken,
    from Yonghong Song.

22) Allow BPF TCP cong-ctls to write app_limited of struct tcp_sock.
    A built-in cc or one from a kernel module is already able to write
    to app_limited, from Yixin Shen.

Conflicts:

Documentation/bpf/bpf_devel_QA.rst
  b7abcd9c65 ("bpf, doc: Link to submitting-patches.rst for general patch submission info")
  0f10f647f4 ("bpf, docs: Use internal linking for link to netdev subsystem doc")
https://lore.kernel.org/all/20230307095812.236eb1be@canb.auug.org.au/

include/net/ip_tunnels.h
  bc9d003dc4 ("ip_tunnel: Preserve pointer const in ip_tunnel_info_opts")
  ac931d4cde ("ipip,ip_tunnel,sit: Add FOU support for externally controlled ipip devices")
https://lore.kernel.org/all/20230413161235.4093777-1-broonie@kernel.org/

net/bpf/test_run.c
  e5995bc7e2 ("bpf, test_run: fix crashes due to XDP frame overwriting/corruption")
  294635a816 ("bpf, test_run: fix &xdp_frame misplacement for LIVE_FRAMES")
https://lore.kernel.org/all/20230320102619.05b80a98@canb.auug.org.au/
====================

Link: https://lore.kernel.org/r/20230413191525.7295-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-04-13 16:43:38 -07:00
David Vernet ec48599abe bpf,docs: Remove references to bpf_cgroup_kptr_get()
The bpf_cgroup_kptr_get() kfunc has been removed, and
bpf_cgroup_acquire() / bpf_cgroup_release() now have the same semantics
as bpf_task_acquire() / bpf_task_release(). This patch updates the BPF
documentation to reflect this.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230411041633.179404-3-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-04-12 12:57:54 -07:00
Dave Thaler 16b7c970cc bpf, docs: Add docs on extended 64-bit immediate instructions
Add docs on extended 64-bit immediate instructions, including six instructions
previously undocumented.  Include a brief description of maps and variables,
as used by those instructions.

V1 -> V2: rebased on top of latest master

V2 -> V3: addressed comments from Alexei

V3 -> V4: addressed comments from David Vernet

Signed-off-by: Dave Thaler <dthaler@microsoft.com>
Link: https://lore.kernel.org/r/20230326054946.2331-1-dthaler1968@googlemail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-04-02 17:02:54 -07:00
David Vernet db9d479ab5 bpf,docs: Update documentation to reflect new task kfuncs
Now that struct task_struct objects are RCU safe, and bpf_task_acquire()
can return NULL, we should update the BPF task kfunc documentation to
reflect the current state of the API.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230331195733.699708-4-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-04-01 09:07:20 -07:00
Dave Thaler 8cfee11071 bpf, docs: Add extended call instructions
Add extended call instructions.  Uses the term "program-local" for
call by offset.  And there are instructions for calling helper functions
by "address" (the old way of using integer values), and for calling
helper functions by BTF ID (for kfuncs).

V1 -> V2: addressed comments from David Vernet

V2 -> V3: make descriptions in table consistent with updated names

V3 -> V4: addressed comments from Alexei

V4 -> V5: fixed alignment

Signed-off-by: Dave Thaler <dthaler@microsoft.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230326033117.1075-1-dthaler1968@googlemail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-03-25 20:58:36 -07:00
David Vernet 6c831c4684 bpf: Treat KF_RELEASE kfuncs as KF_TRUSTED_ARGS
KF_RELEASE kfuncs are not currently treated as having KF_TRUSTED_ARGS,
even though they have a superset of the requirements of KF_TRUSTED_ARGS.
Like KF_TRUSTED_ARGS, KF_RELEASE kfuncs require a 0-offset argument, and
don't allow NULL-able arguments. Unlike KF_TRUSTED_ARGS which require
_either_ an argument with ref_obj_id > 0, _or_ (ref->type &
BPF_REG_TRUSTED_MODIFIERS) (and no unsafe modifiers allowed), KF_RELEASE
only allows for ref_obj_id > 0.  Because KF_RELEASE today doesn't
automatically imply KF_TRUSTED_ARGS, some of these requirements are
enforced in different ways that can make the behavior of the verifier
feel unpredictable. For example, a KF_RELEASE kfunc with a NULL-able
argument will currently fail in the verifier with a message like, "arg#0
is ptr_or_null_ expected ptr_ or socket" rather than "Possibly NULL
pointer passed to trusted arg0". Our intention is the same, but the
semantics are different due to implemenetation details that kfunc authors
and BPF program writers should not need to care about.

Let's make the behavior of the verifier more consistent and intuitive by
having KF_RELEASE kfuncs imply the presence of KF_TRUSTED_ARGS. Our
eventual goal is to have all kfuncs assume KF_TRUSTED_ARGS by default
anyways, so this takes us a step in that direction.

Note that it does not make sense to assume KF_TRUSTED_ARGS for all
KF_ACQUIRE kfuncs. KF_ACQUIRE kfuncs can have looser semantics than
KF_RELEASE, with e.g. KF_RCU | KF_RET_NULL. We may want to have
KF_ACQUIRE imply KF_TRUSTED_ARGS _unless_ KF_RCU is specified, but that
can be left to another patch set, and there are no such subtleties to
address for KF_RELEASE.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230325213144.486885-4-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-03-25 16:56:22 -07:00
Sreevani Sreejith 08ff1c9f3e bpf, docs: Libbpf overview documentation
This patch documents overview of libbpf, including its features for
developing BPF programs.

Signed-off-by: Sreevani Sreejith <ssreevani@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230315195405.2051559-1-ssreevani@meta.com
2023-03-18 10:17:39 -07:00
Bagas Sanjaya 0f10f647f4 bpf, docs: Use internal linking for link to netdev subsystem doc
Commit d56b0c461d ("bpf, docs: Fix link to netdev-FAQ target")
attempts to fix linking problem to undefined "netdev-FAQ" label
introduced in 287f4fa99a ("docs: Update references to netdev-FAQ")
by changing internal cross reference to netdev subsystem documentation
(Documentation/process/maintainer-netdev.rst) to external one at
docs.kernel.org. However, the linking problem is still not
resolved, as the generated link points to non-existent netdev-FAQ
section of the external doc, which when clicked, will instead going
to the top of the doc.

Revert back to internal linking by simply mention the doc path while
massaging the leading text to the link, since the netdev subsystem
doc contains no FAQs but rather general information about the subsystem.

Fixes: d56b0c461d ("bpf, docs: Fix link to netdev-FAQ target")
Fixes: 287f4fa99a ("docs: Update references to netdev-FAQ")
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230314074449.23620-1-bagasdotme@gmail.com
2023-03-17 13:58:57 +01:00
David Vernet fec2c6d14f bpf,docs: Remove bpf_cpumask_kptr_get() from documentation
Now that the kfunc no longer exists, we can remove it and instead
describe how RCU can be used to get a struct bpf_cpumask from a map
value. This patch updates the BPF documentation accordingly.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230316054028.88924-6-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-03-16 12:28:30 -07:00
Dave Thaler b9fe8e8d03 bpf, docs: Add signed comparison example
Improve clarity by adding an example of a signed comparison instruction

Signed-off-by: Dave Thaler <dthaler@microsoft.com>
Acked-by: David Vernet <void@manifault.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20230310233814.4641-1-dthaler1968@googlemail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-03-13 22:10:45 -07:00
Dave Thaler c1f9e14e3b bpf, docs: Explain helper functions
Add brief text about existence of helper functions, with details to go in
separate psABI text.

Note that text about runtime functions (kfuncs) is part of a separate patch,
not this one.

Signed-off-by: Dave Thaler <dthaler@microsoft.com>
Link: https://lore.kernel.org/r/20230308205303.1308-1-dthaler1968@googlemail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-03-10 13:02:00 -08:00
Jakub Kicinski d0ddf5065f Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Documentation/bpf/bpf_devel_QA.rst
  b7abcd9c65 ("bpf, doc: Link to submitting-patches.rst for general patch submission info")
  d56b0c461d ("bpf, docs: Fix link to netdev-FAQ target")
https://lore.kernel.org/all/20230307095812.236eb1be@canb.auug.org.au/

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-03-09 22:22:11 -08:00
Bagas Sanjaya b7abcd9c65 bpf, doc: Link to submitting-patches.rst for general patch submission info
The link for patch submission information in general refers to index
page for "Working with the kernel development community" section of
kernel docs, whereas the link should have been
Documentation/process/submitting-patches.rst instead.

Fix it by replacing the index target with the appropriate doc.

Fixes: 5422283848 ("bpf, doc: convert bpf_devel_QA.rst to use RST formatting")
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230228074523.11493-3-bagasdotme@gmail.com
2023-03-06 16:44:39 +01:00
Bagas Sanjaya 32db18d606 bpf, doc: Do not link to docs.kernel.org for kselftest link
The question on how to run BPF selftests have a reference link to kernel
selftest documentation (Documentation/dev-tools/kselftest.rst). However,
it uses external link to the documentation at kernel.org/docs (aka
docs.kernel.org) instead, which requires Internet access.

Fix this and replace the link with internal linking, by using :doc: directive
while keeping the anchor text.

Fixes: b7a27c3aaf ("bpf, doc: howto use/run the BPF selftests")
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230228074523.11493-2-bagasdotme@gmail.com
2023-03-06 16:44:34 +01:00
Alexei Starovoitov 20c09d92fa bpf: Introduce kptr_rcu.
The life time of certain kernel structures like 'struct cgroup' is protected by RCU.
Hence it's safe to dereference them directly from __kptr tagged pointers in bpf maps.
The resulting pointer is MEM_RCU and can be passed to kfuncs that expect KF_RCU.
Derefrence of other kptr-s returns PTR_UNTRUSTED.

For example:
struct map_value {
   struct cgroup __kptr *cgrp;
};

SEC("tp_btf/cgroup_mkdir")
int BPF_PROG(test_cgrp_get_ancestors, struct cgroup *cgrp_arg, const char *path)
{
  struct cgroup *cg, *cg2;

  cg = bpf_cgroup_acquire(cgrp_arg); // cg is PTR_TRUSTED and ref_obj_id > 0
  bpf_kptr_xchg(&v->cgrp, cg);

  cg2 = v->cgrp; // This is new feature introduced by this patch.
  // cg2 is PTR_MAYBE_NULL | MEM_RCU.
  // When cg2 != NULL, it's a valid cgroup, but its percpu_ref could be zero

  if (cg2)
    bpf_cgroup_ancestor(cg2, level); // safe to do.
}

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230303041446.3630-4-alexei.starovoitov@gmail.com
2023-03-03 17:42:20 +01:00
Alexei Starovoitov 03b77e17ae bpf: Rename __kptr_ref -> __kptr and __kptr -> __kptr_untrusted.
__kptr meant to store PTR_UNTRUSTED kernel pointers inside bpf maps.
The concept felt useful, but didn't get much traction,
since bpf_rdonly_cast() was added soon after and bpf programs received
a simpler way to access PTR_UNTRUSTED kernel pointers
without going through restrictive __kptr usage.

Rename __kptr_ref -> __kptr and __kptr -> __kptr_untrusted to indicate
its intended usage.
The main goal of __kptr_untrusted was to read/write such pointers
directly while bpf_kptr_xchg was a mechanism to access refcnted
kernel pointers. The next patch will allow RCU protected __kptr access
with direct read. At that point __kptr_untrusted will be deprecated.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230303041446.3630-2-alexei.starovoitov@gmail.com
2023-03-03 17:42:20 +01:00
David Vernet cacad346f6 bpf, docs: Fix final bpf docs build failure
maps.rst in the BPF documentation links to the
/userspace-api/ebpf/syscall document
(Documentation/userspace-api/ebpf/syscall.rst). For some reason, if you
try to reference the document with :doc:, the docs build emits the
following warning:

./Documentation/bpf/maps.rst:13: WARNING: \
    unknown document: '/userspace-api/ebpf/syscall'

It appears that other places in the docs tree also don't support using
:doc:. Elsewhere in the BPF documentation, we just reference the kernel
docs page directly. Let's do that here to clean up the last remaining
noise in the docs build.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230302183918.54190-2-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-03-02 22:36:10 -08:00
David Vernet d56b0c461d bpf, docs: Fix link to netdev-FAQ target
The BPF devel Q&A documentation page makes frequent reference to the
netdev-QA page via the netdev-FAQ rst link. This link is currently
broken, as is evidenced by the build output when making BPF docs:

./Documentation/bpf/bpf_devel_QA.rst:150: WARNING: undefined label: 'netdev-faq'
./Documentation/bpf/bpf_devel_QA.rst:206: WARNING: undefined label: 'netdev-faq'
./Documentation/bpf/bpf_devel_QA.rst:231: WARNING: undefined label: 'netdev-faq'
./Documentation/bpf/bpf_devel_QA.rst:396: WARNING: undefined label: 'netdev-faq'
./Documentation/bpf/bpf_devel_QA.rst:412: WARNING: undefined label: 'netdev-faq'

Fix the links to point to the actual netdev-faq page.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230302183918.54190-1-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-03-02 22:36:10 -08:00
David Vernet db52b587c6 bpf, docs: Fix __uninit kfunc doc section
In commit d96d937d7c ("bpf: Add __uninit kfunc annotation"), the
__uninit kfunc annotation was documented in kfuncs.rst. You have to
fully underline a section in rst, or the build will issue a warning that
the title underline is too short:

./Documentation/bpf/kfuncs.rst:104: WARNING: Title underline too short.

2.2.2 __uninit Annotation
--------------------

This patch fixes that title underline.

Fixes: d96d937d7c ("bpf: Add __uninit kfunc annotation")
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230301194910.602738-2-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-03-01 16:00:10 -08:00
Joanne Koong d96d937d7c bpf: Add __uninit kfunc annotation
This patch adds __uninit as a kfunc annotation.

This will be useful for scenarios such as for example in dynptrs,
indicating whether the dynptr should be checked by the verifier as an
initialized or an uninitialized dynptr.

Without this annotation, the alternative would be needing to hard-code
in the verifier the specific kfunc to indicate that arg should be
treated as an uninitialized arg.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://lore.kernel.org/r/20230301154953.641654-7-joannelkoong@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-03-01 09:55:24 -08:00
Jose E. Marchesi ae256f9547 bpf, docs: Document BPF insn encoding in term of stored bytes
[Changes from V4:
- s/regs:16/regs:8 in figure.]

[Changes from V3:
- Back to src_reg and dst_reg, since they denote register numbers
  as opposed to the values stored in these registers.]

[Changes from V2:
- Use src and dst consistently in the document.
- Use a more graphical depiction of the 128-bit instruction.
- Remove `Where:' fragment.
- Clarify that unused bits are reserved and shall be zeroed.]

[Changes from V1:
- Use rst literal blocks for figures.
- Avoid using | in the basic instruction/pseudo instruction figure.
- Rebased to today's bpf-next master branch.]

This patch modifies instruction-set.rst so it documents the encoding
of BPF instructions in terms of how the bytes are stored (be it in an
ELF file or as bytes in a memory buffer to be loaded into the kernel
or some other BPF consumer) as opposed to how the instruction looks
like once loaded.

This is hopefully easier to understand by implementors looking to
generate and/or consume bytes conforming BPF instructions.

The patch also clarifies that the unused bytes in a pseudo-instruction
shall be cleared with zeros.

Signed-off-by: Jose E. Marchesi <jose.marchesi@oracle.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/87h6v6i0da.fsf_-_@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-02-28 09:55:18 -08:00
Bagas Sanjaya a07484c083 bpf, docs: Fix link to BTF doc
Ross reported broken link to BTF documentation
(Documentation/bpf/btf.rst) in Documentation/bpf/bpf_devel_QA.rst. The
link in question is written using external link syntax, with the target
refers to BTF doc in reST source (btf.rst), which doesn't exist in
resulting HTML output.

Fix the link by replacing external link syntax with simply writing out
the target doc, which the link will be generated to the correct HTML doc
target.

Fixes: 6736aa793c ("selftests/bpf: Add general instructions for test execution")
Reported-by: Ross Zwisler <zwisler@google.com>
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Ross Zwisler <zwisler@google.com>
Link: https://lore.kernel.org/linux-doc/Y++09LKx25dtR4Ow@google.com/
Link: https://lore.kernel.org/bpf/20230222083530.26136-1-bagasdotme@gmail.com
2023-02-27 21:54:14 +01:00
Tejun Heo 332ea1f697 bpf: Add bpf_cgroup_from_id() kfunc
cgroup ID is an userspace-visible 64bit value uniquely identifying a given
cgroup. As the IDs are used widely, it's useful to be able to look up the
matching cgroups. Add bpf_cgroup_from_id().

v2: Separate out selftest into its own patch as suggested by Alexei.

Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/Y/bBaG96t0/gQl9/@slm.duckdns.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-02-23 08:33:05 -08:00
Dave Thaler 746ce76712 bpf, docs: Add explanation of endianness
Document the discussion from the email thread on the IETF bpf list,
where it was explained that the raw format varies by endianness
of the processor.

Signed-off-by: Dave Thaler <dthaler@microsoft.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230220223742.1347-1-dthaler1968@googlemail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-02-22 14:04:55 -08:00
Bagas Sanjaya e2d323a1f0 Documentation: bpf: Add missing line break separator in node_data struct code block
Stephen Rothwell reported htmldocs warning when merging bpf-next tree,
which was the same warning as reported by kernel test robot:

Documentation/bpf/graph_ds_impl.rst:62: ERROR: Error in "code-block" directive:
maximum 1 argument(s) allowed, 12 supplied.

The error is due to Sphinx confuses node_data struct declaration with
code-block directive option.

Fix the warning by separating the code-block marker with node_data struct
declaration.

Link: https://lore.kernel.org/linux-next/20230215144505.4751d823@canb.auug.org.au/
Link: https://lore.kernel.org/linux-doc/202302151123.wUE5FYFx-lkp@intel.com/
Fixes: c31315c3aa ("bpf, documentation: Add graph documentation for non-owning refs")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/20230215123253.41552-3-bagasdotme@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-02-15 08:43:51 -08:00
Dave Marchevsky c31315c3aa bpf, documentation: Add graph documentation for non-owning refs
It is difficult to intuit the semantics of owning and non-owning
references from verifier code. In order to keep the high-level details
from being lost in the mailing list, this patch adds documentation
explaining semantics and details.

The target audience of doc added in this patch is folks working on BPF
internals, as there's focus on "what should the verifier do here". Via
reorganization or copy-and-paste, much of the content can probably be
repurposed for BPF program writer audience as well.

Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230214004017.2534011-9-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-02-13 19:40:53 -08:00
Dave Thaler d00d5b82f0 bpf, docs: Add note about type convention
Add explanation about use of "u64", "u32", etc. as
the type convention used in BPF documentation.

Signed-off-by: Dave Thaler <dthaler@microsoft.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230127014706.1005-1-dthaler1968@googlemail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-02-08 09:25:26 -08:00
Toke Høiland-Jørgensen 27b53b7364 bpf/docs: Update design QA to be consistent with kfunc lifecycle docs
Cong pointed out that there are some inconsistencies between the BPF design
QA and the lifecycle expectations documentation we added for kfuncs. Let's
update the QA file to be consistent with the kfunc docs, and add references
where it makes sense. Also document that modules may export kfuncs now.

v3:
- Grammar nit + ack from David

v2:
- Fix repeated word (s/defined defined/defined/)

Reported-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: David Vernet <void@manifault.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20230208164143.286392-1-toke@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-02-08 09:24:16 -08:00
Dave Thaler a92adde8d3 bpf, docs: Use consistent names for the same field
Use consistent names for the same field, e.g., 'dst' vs 'dst_reg'.
Previously a mix of terms were used for the same thing in various cases.

Signed-off-by: Dave Thaler <dthaler@microsoft.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230127224555.916-1-dthaler1968@googlemail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-02-07 18:45:43 -08:00
David Vernet 16c294a6aa bpf/docs: Document kfunc lifecycle / stability expectations
BPF kernel <-> kernel API stability has been discussed at length over
the last several weeks and months. Now that we've largely aligned over
kfuncs being the way forward, and BPF helpers being considered
functionally frozen, it's time to document the expectations for kfunc
lifecycles and stability so that everyone (BPF users, kfunc developers,
and maintainers) are all aligned, and have a crystal-clear understanding
of the expectations surrounding kfuncs.

To do that, this patch adds that documentation to the main kfuncs
documentation page via a new 'kfunc lifecycle expectations' section. The
patch describes how decisions are made in the kernel regarding whether
to include, keep, deprecate, or change / remove a kfunc. As described
very overtly in the patch itself, but likely worth highlighting here:

"kfunc stability" does not mean, nor ever will mean, "BPF APIs may block
development elsewhere in the kernel".

Rather, the intention and expectation is for kfuncs to be treated like
EXPORT_SYMBOL_GPL symbols in the kernel. The goal is for kfuncs to be a
safe and valuable option for maintainers and kfunc developers to extend
the kernel, without tying anyone's hands, or imposing any kind of
restrictions on maintainers in the same way that UAPI changes do.

In addition to the 'kfunc lifecycle expectations' section, this patch
also adds documentation for a new KF_DEPRECATED kfunc flag which kfunc
authors or maintainers can choose to add to kfuncs if and when they
decide to deprecate them. Note that as described in the patch itself, a
kfunc need not be deprecated before being changed or removed -- this
flag is simply provided as an available deprecation mechanism for those
that want to provide a deprecation story / timeline to their users.
When necessary, kfuncs may be changed or removed to accommodate changes
elsewhere in the kernel without any deprecation at all.

Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Co-developed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230203155727.793518-2-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-02-03 09:01:29 -08:00
Eduard Zingerman cb6018485c docs/bpf: Add description of register liveness tracking algorithm
This is a followup for [1], adds an overview for the register liveness
tracking, covers the following points:
- why register liveness tracking is useful;
- how register parentage chains are constructed;
- how liveness marks are applied using the parentage chains.

[1] https://lore.kernel.org/bpf/CAADnVQKs2i1iuZ5SUGuJtxWVfGYR9kDgYKhq3rNV+kBLQCu7rA@mail.gmail.com/

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Reviewed-by: Edward Cree <ecree.xilinx@gmail.com>
Link: https://lore.kernel.org/r/20230202125713.821931-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-02-02 20:21:59 -08:00
David Vernet 98e6ab7a04 bpf: Document usage of the new __bpf_kfunc macro
Now that the __bpf_kfunc macro has been added to linux/btf.h, include a
blurb about it in the kfuncs.rst file. In order for the macro to
successfully render with .. kernel-doc, we'll also need to add it to the
c_id_attributes array.

Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20230201173016.342758-3-void@manifault.com
2023-02-02 00:25:14 +01:00
Randy Dunlap 1d3cab43f4 Documentation: bpf: correct spelling
Correct spelling problems for Documentation/bpf/ as reported
by codespell.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/20230128195046.13327-1-rdunlap@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-28 12:22:20 -08:00
David Vernet 027bdec893 bpf/docs: Document the nocast aliasing behavior of ___init
When comparing BTF IDs for pointers being passed to kfunc arguments, the
verifier will allow pointer types that are equivalent according to the C
standard. For example, for:

struct bpf_cpumask {
	cpumask_t cpumask;
	refcount_t usage;
};

The verifier will allow a struct bpf_cpumask * to be passed to a kfunc
that takes a const struct cpumask * (cpumask_t is a typedef of struct
cpumask). The exception to this rule is if a type is suffixed with
___init, such as:

struct nf_conn___init {
	struct nf_conn ct;
};

The verifier will _not_ allow a struct nf_conn___init * to be passed to
a kfunc that expects a struct nf_conn *. This patch documents this
behavior in the kfuncs documentation page.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125143816.721952-8-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 07:57:50 -08:00
David Vernet d94cbde218 bpf/docs: Document how nested trusted fields may be defined
A prior change defined a new BTF_TYPE_SAFE_NESTED macro in the verifier
which allows developers to specify when a pointee field in a struct type
should inherit its parent pointer's trusted status. This patch updates
the kfuncs documentation to specify this macro and how it can be used.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125143816.721952-7-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 07:57:50 -08:00
David Vernet bdbda39584 bpf/docs: Document cpumask kfuncs in a new file
Now that we've added a series of new cpumask kfuncs, we should document
them so users can easily use them. This patch adds a new cpumasks.rst
file to document them.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125143816.721952-6-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 07:57:50 -08:00
Dave Thaler 0eb9d19e22 bpf, docs: Fix modulo zero, division by zero, overflow, and underflow
Fix modulo zero, division by zero, overflow, and underflow. Also clarify how
a negative immediate value is used in unsigned division.

Signed-off-by: Dave Thaler <dthaler@microsoft.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230124001218.827-1-dthaler1968@googlemail.com
2023-01-24 16:46:40 +01:00
Jakub Kicinski d75858ef10 bpf-next-for-netdev
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Daniel Borkmann says:

====================
bpf-next 2023-01-04

We've added 45 non-merge commits during the last 21 day(s) which contain
a total of 50 files changed, 1454 insertions(+), 375 deletions(-).

The main changes are:

1) Fixes, improvements and refactoring of parts of BPF verifier's
   state equivalence checks, from Andrii Nakryiko.

2) Fix a few corner cases in libbpf's BTF-to-C converter in particular
   around padding handling and enums, also from Andrii Nakryiko.

3) Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better
  support decap on GRE tunnel devices not operating in collect metadata,
  from Christian Ehrig.

4) Improve x86 JIT's codegen for PROBE_MEM runtime error checks,
   from Dave Marchevsky.

5) Remove the need for trace_printk_lock for bpf_trace_printk
   and bpf_trace_vprintk helpers, from Jiri Olsa.

6) Add proper documentation for BPF_MAP_TYPE_SOCK{MAP,HASH} maps,
   from Maryam Tahhan.

7) Improvements in libbpf's btf_parse_elf error handling, from Changbin Du.

8) Bigger batch of improvements to BPF tracing code samples,
   from Daniel T. Lee.

9) Add LoongArch support to libbpf's bpf_tracing helper header,
   from Hengqi Chen.

10) Fix a libbpf compiler warning in perf_event_open_probe on arm32,
    from Khem Raj.

11) Optimize bpf_local_storage_elem by removing 56 bytes of padding,
    from Martin KaFai Lau.

12) Use pkg-config to locate libelf for resolve_btfids build,
    from Shen Jiamin.

13) Various libbpf improvements around API documentation and errno
    handling, from Xin Liu.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (45 commits)
  libbpf: Return -ENODATA for missing btf section
  libbpf: Add LoongArch support to bpf_tracing.h
  libbpf: Restore errno after pr_warn.
  libbpf: Added the description of some API functions
  libbpf: Fix invalid return address register in s390
  samples/bpf: Use BPF_KSYSCALL macro in syscall tracing programs
  samples/bpf: Fix tracex2 by using BPF_KSYSCALL macro
  samples/bpf: Change _kern suffix to .bpf with syscall tracing program
  samples/bpf: Use vmlinux.h instead of implicit headers in syscall tracing program
  samples/bpf: Use kyscall instead of kprobe in syscall tracing program
  bpf: rename list_head -> graph_root in field info types
  libbpf: fix errno is overwritten after being closed.
  bpf: fix regs_exact() logic in regsafe() to remap IDs correctly
  bpf: perform byte-by-byte comparison only when necessary in regsafe()
  bpf: reject non-exact register type matches in regsafe()
  bpf: generalize MAYBE_NULL vs non-MAYBE_NULL rule
  bpf: reorganize struct bpf_reg_state fields
  bpf: teach refsafe() to take into account ID remapping
  bpf: Remove unused field initialization in bpf's ctl_table
  selftests/bpf: Add jit probe_mem corner case tests to s390x denylist
  ...
====================

Link: https://lore.kernel.org/r/20230105000926.31350-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-01-04 20:21:25 -08:00
Maryam Tahhan cafb92d719 docs: BPF_MAP_TYPE_SOCK[MAP|HASH]
Add documentation for BPF_MAP_TYPE_SOCK[MAP|HASH]
including kernel versions introduced, usage
and examples.

Signed-off-by: Maryam Tahhan <mtahhan@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20221219095512.26534-1-mtahhan@redhat.com
2022-12-20 15:54:05 -08:00
Donald Hunter d2b497a973 docs/bpf: Reword docs for BPF_MAP_TYPE_SK_STORAGE
Improve the grammar of the function descriptions and highlight
that the key is a socket fd.

Fixes: f3212ad5b7 ("docs/bpf: Add documentation for BPF_MAP_TYPE_SK_STORAGE")
Reported-by: Martin KaFai Lau <martin.lau@linux.dev>
Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20221212101600.56026-1-donald.hunter@gmail.com
2022-12-14 18:35:41 +01:00
Donald Hunter f3212ad5b7 docs/bpf: Add documentation for BPF_MAP_TYPE_SK_STORAGE
Add documentation for the BPF_MAP_TYPE_SK_STORAGE including
kernel version introduced, usage and examples.

Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221209112401.69319-1-donald.hunter@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-12-09 09:42:16 -08:00
David Vernet 36aa10ffd6 bpf/docs: Document struct cgroup * kfuncs
bpf_cgroup_acquire(), bpf_cgroup_release(), bpf_cgroup_kptr_get(), and
bpf_cgroup_ancestor(), are kfuncs that were recently added to
kernel/bpf/helpers.c. These are "core" kfuncs in that they're available
for use in any tracepoint or struct_ops BPF program. Though they have no
ABI stability guarantees, we should still document them. This patch adds
a struct cgroup * subsection to the Core kfuncs section which describes
each of these kfuncs.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221207204911.873646-3-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-12-07 17:11:24 -08:00
David Vernet 25c5e92d19 bpf/docs: Document struct task_struct * kfuncs
bpf_task_acquire(), bpf_task_release(), and bpf_task_from_pid() are
kfuncs that were recently added to kernel/bpf/helpers.c. These are
"core" kfuncs in that they're available for use for any tracepoint or
struct_ops BPF program. Though they have no ABI stability guarantees, we
should still document them. This patch adds a new Core kfuncs section to
the BPF kfuncs doc, and adds entries for all of these task kfuncs.

Note that bpf_task_kptr_get() is not documented, as it still returns
NULL while we're working to resolve how it can use RCU to ensure struct
task_struct * lifetime.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221207204911.873646-2-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-12-07 17:09:13 -08:00
Sreevani Sreejith 8972e18a43 bpf, docs: BPF Iterator Document
Document that describes how BPF iterators work, how to use iterators,
and how to pass parameters in BPF iterators.

Acked-by: David Vernet <void@manifault.com>
Signed-off-by: Sreevani Sreejith <psreep@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221202221710.320810-2-ssreevani@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-12-04 16:41:22 -08:00
Yonghong Song f536256498 docs/bpf: Add KF_RCU documentation
Add proper KF_RCU documentation in kfuncs.rst.

Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221203184613.478967-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-12-04 12:52:40 -08:00
Zheng Yejian bc067cacb6 bpf, docs: Correct the example of BPF_XOR
Refer to description of BPF_XOR, dst_reg should be used but not src_reg
in the examples.

Fixes: be3193cded ("bpf, docs: Add subsections for ALU and JMP instructions")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221129134558.2757043-1-zhengyejian1@huawei.com
2022-12-02 21:27:32 +01:00
Maryam Tahhan 2b3e8f6f5b docs/bpf: Add BPF_MAP_TYPE_XSKMAP documentation
Add documentation for BPF_MAP_TYPE_XSKMAP including kernel version introduced,
usage and examples.

Signed-off-by: Maryam Tahhan <mtahhan@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221123090043.83945-1-mtahhan@redhat.com
2022-11-25 00:33:14 +01:00