snprintf() does not return negative error code on error, it returns the
number of characters which *would* be generated for the given input.

Fix the error handling check.

Fixes: 57539b1c0ac2 ("bpf: Enable annotating trusted nested pointers")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/393bdebc87b22563c08ace094defa7160eb7a6c0.1694190795.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Pull probes updates from Masami Hiramatsu:

 - kprobes: use struct_size() for variable size kretprobe_instance data
   structure.

 - eprobe: Simplify trace_eprobe list iteration.

 - probe events: Data structure field access support on BTF argument.

     - Update BTF argument support on the functions in the kernel
       loadable modules (only loaded modules are supported).

     - Move generic BTF access function (search function prototype and
       get function parameters) to a separated file.

     - Add a function to search a member of data structure in BTF.

     - Support accessing BTF data structure member from probe args by
       C-like arrow('->') and dot('.') operators. e.g.
          't sched_switch next=next->pid vruntime=next->se.vruntime'

     - Support accessing BTF data structure member from $retval. e.g.
          'f getname_flags%return +0($retval->name):string'

     - Add string type checking if BTF type info is available. This will
       reject if user specify ":string" type for non "char pointer"
       type.

     - Automatically assume the fprobe event as a function return event
       if $retval is used.

 - selftests/ftrace: Add BTF data field access test cases.

 - Documentation: Update fprobe event example with BTF data field.

* tag 'probes-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  Documentation: tracing: Update fprobe event example with BTF field
  selftests/ftrace: Add BTF fields access testcases
  tracing/fprobe-event: Assume fprobe is a return event by $retval
  tracing/probes: Add string type check with BTF
  tracing/probes: Support BTF field access from $retval
  tracing/probes: Support BTF based data structure field access
  tracing/probes: Add a function to search a member of a struct/union
  tracing/probes: Move finding func-proto API and getting func-param API to trace_btf
  tracing/probes: Support BTF argument on module functions
  tracing/eprobe: Iterate trace_eprobe directly
  kernel: kprobes: Use struct_size()

Since the btf returned from bpf_get_btf_vmlinux() only covers functions in
the vmlinux, BTF argument is not available on the functions in the modules.
Use bpf_find_btf_id() instead of bpf_get_btf_vmlinux()+btf_find_name_kind()
so that BTF argument can find the correct struct btf and btf_type in it.
With this fix, fprobe events can use `$arg*` on module functions as below

 # grep nf_log_ip_packet /proc/kallsyms
ffffffffa0005c00 t nf_log_ip_packet	[nf_log_syslog]
ffffffffa0005bf0 t __pfx_nf_log_ip_packet	[nf_log_syslog]
 # echo 'f nf_log_ip_packet $arg*' > dynamic_events
 # cat dynamic_events
f:fprobes/nf_log_ip_packet__entry nf_log_ip_packet net=net pf=pf hooknum=hooknum skb=skb in=in out=out loginfo=loginfo prefix=prefix

To support the module's btf which is removable, the struct btf needs to be
ref-counted. So this also records the btf in the traceprobe_parse_context
and returns the refcount when the parse has done.

Link: https://lore.kernel.org/all/169272154223.160970.3507930084247934031.stgit@devnote2/

Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>

xdp.h is far more specific and is included in only 67 other
files vs netdevice.h's 1538 include sites.
Make xdp.h include netdevice.h, instead of the other way around.
This decreases the incremental allmodconfig builds size when
xdp.h is touched from 5947 to 662 objects.

Move bpf_prog_run_xdp() to xdp.h, seems appropriate and filter.h
is a mega-header in its own right so it's nice to avoid xdp.h
getting included there as well.

The only unfortunate part is that the typedef for xdp_features_t
has to move to netdevice.h, since its embedded in struct netdevice.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://lore.kernel.org/r/20230803010230.1755386-4-kuba@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

Alexei Starovoitov says:

====================
pull-request: bpf-next 2023-07-13

We've added 67 non-merge commits during the last 15 day(s) which contain
a total of 106 files changed, 4444 insertions(+), 619 deletions(-).

The main changes are:

1) Fix bpftool build in presence of stale vmlinux.h,
   from Alexander Lobakin.

2) Introduce bpf_me_mcache_free_rcu() and fix OOM under stress,
   from Alexei Starovoitov.

3) Teach verifier actual bounds of bpf_get_smp_processor_id()
   and fix perf+libbpf issue related to custom section handling,
   from Andrii Nakryiko.

4) Introduce bpf map element count, from Anton Protopopov.

5) Check skb ownership against full socket, from Kui-Feng Lee.

6) Support for up to 12 arguments in BPF trampoline, from Menglong Dong.

7) Export rcu_request_urgent_qs_task, from Paul E. McKenney.

8) Fix BTF walking of unions, from Yafang Shao.

9) Extend link_info for kprobe_multi and perf_event links,
   from Yafang Shao.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (67 commits)
  selftests/bpf: Add selftest for PTR_UNTRUSTED
  bpf: Fix an error in verifying a field in a union
  selftests/bpf: Add selftests for nested_trust
  bpf: Fix an error around PTR_UNTRUSTED
  selftests/bpf: add testcase for TRACING with 6+ arguments
  bpf, x86: allow function arguments up to 12 for TRACING
  bpf, x86: save/restore regs with BPF_DW size
  bpftool: Use "fallthrough;" keyword instead of comments
  bpf: Add object leak check.
  bpf: Convert bpf_cpumask to bpf_mem_cache_free_rcu.
  bpf: Introduce bpf_mem_free_rcu() similar to kfree_rcu().
  selftests/bpf: Improve test coverage of bpf_mem_alloc.
  rcu: Export rcu_request_urgent_qs_task()
  bpf: Allow reuse from waiting_for_gp_ttrace list.
  bpf: Add a hint to allocated objects.
  bpf: Change bpf_mem_cache draining process.
  bpf: Further refactor alloc_bulk().
  bpf: Factor out inc/dec of active flag into helpers.
  bpf: Refactor alloc_bulk().
  bpf: Let free_all() return the number of freed elements.
  ...
====================

Link: https://lore.kernel.org/r/20230714020910.80794-1-alexei.starovoitov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

We are utilizing BPF LSM to monitor BPF operations within our container
environment. When we add support for raw_tracepoint, it hits below
error.

; (const void *)attr->raw_tracepoint.name);
27: (79) r3 = *(u64 *)(r2 +0)
access beyond the end of member map_type (mend:4) in struct (anon) with off 0 size 8

It can be reproduced with below BPF prog.

SEC("lsm/bpf")
int BPF_PROG(bpf_audit, int cmd, union bpf_attr *attr, unsigned int size)
{
	switch (cmd) {
	case BPF_RAW_TRACEPOINT_OPEN:
		bpf_printk("raw_tracepoint is %s", attr->raw_tracepoint.name);
		break;
	default:
		break;
	}
	return 0;
}

The reason is that when accessing a field in a union, such as bpf_attr,
if the field is located within a nested struct that is not the first
member of the union, it can result in incorrect field verification.

  union bpf_attr {
      struct {
          __u32 map_type; <<<< Actually it will find that field.
          __u32 key_size;
          __u32 value_size;
         ...
      };
      ...
      struct {
          __u64 name;    <<<< We want to verify this field.
          __u32 prog_fd;
      } raw_tracepoint;
  };

Considering the potential deep nesting levels, finding a perfect
solution to address this issue has proven challenging. Therefore, I
propose a solution where we simply skip the verification process if the
field in question is located within a union.

Fixes: 7e3617a72df3 ("bpf: Add array support to btf_struct_access")
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230713025642.27477-4-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Per discussion with Alexei, the PTR_UNTRUSTED flag should not been
cleared when we start to walk a new struct, because the struct in
question may be a struct nested in a union. We should also check and set
this flag before we walk its each member, in case itself is a union.
We will clear this flag if the field is BTF_TYPE_SAFE_RCU_OR_NULL.

Fixes: 6fcd486b3a0a ("bpf: Refactor RCU enforcement in the verifier.")
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230713025642.27477-2-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

__register_btf_kfunc_id_set() assumes .BTF to be part of the module's .ko
file if CONFIG_DEBUG_INFO_BTF is enabled. If that's not the case, the
function prints an error message and return an error. As a result, such
modules cannot be loaded.

However, the section could be stripped out during a build process. It would
be better to let the modules loaded, because their basic functionalities
have no problem [0], though the BTF functionalities will not be supported.
Make the function to lower the level of the message from error to warn, and
return no error.

  [0] https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion

Fixes: c446fdacb10d ("bpf: fix register_btf_kfunc_id_set for !CONFIG_DEBUG_INFO_BTF")
Reported-by: Alexander Egorenkov <Alexander.Egorenkov@ibm.com>
Suggested-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/87y228q66f.fsf@oc8242746057.ibm.com
Link: https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion
Link: https://lore.kernel.org/bpf/20230701171447.56464-1-sj@kernel.org

It is impossible to use skb_frag_t in the tracing program. Resolve typedefs
when walking structs.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20230626212522.2414485-1-sdf@google.com

Daniel Borkmann says:

====================
pull-request: bpf-next 2023-06-23

We've added 49 non-merge commits during the last 24 day(s) which contain
a total of 70 files changed, 1935 insertions(+), 442 deletions(-).

The main changes are:

1) Extend bpf_fib_lookup helper to allow passing the route table ID,
   from Louis DeLosSantos.

2) Fix regsafe() in verifier to call check_ids() for scalar registers,
   from Eduard Zingerman.

3) Extend the set of cpumask kfuncs with bpf_cpumask_first_and()
   and a rework of bpf_cpumask_any*() kfuncs. Additionally,
   add selftests, from David Vernet.

4) Fix socket lookup BPF helpers for tc/XDP to respect VRF bindings,
   from Gilad Sever.

5) Change bpf_link_put() to use workqueue unconditionally to fix it
   under PREEMPT_RT, from Sebastian Andrzej Siewior.

6) Follow-ups to address issues in the bpf_refcount shared ownership
   implementation, from Dave Marchevsky.

7) A few general refactorings to BPF map and program creation permissions
   checks which were part of the BPF token series, from Andrii Nakryiko.

8) Various fixes for benchmark framework and add a new benchmark
   for BPF memory allocator to BPF selftests, from Hou Tao.

9) Documentation improvements around iterators and trusted pointers,
   from Anton Protopopov.

10) Small cleanup in verifier to improve allocated object check,
    from Daniel T. Lee.

11) Improve performance of bpf_xdp_pointer() by avoiding access
    to shared_info when XDP packet does not have frags,
    from Jesper Dangaard Brouer.

12) Silence a harmless syzbot-reported warning in btf_type_id_size(),
    from Yonghong Song.

13) Remove duplicate bpfilter_umh_cleanup in favor of umd_cleanup_helper,
    from Jarkko Sakkinen.

14) Fix BPF selftests build for resolve_btfids under custom HOSTCFLAGS,
    from Viktor Malik.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (49 commits)
  bpf, docs: Document existing macros instead of deprecated
  bpf, docs: BPF Iterator Document
  selftests/bpf: Fix compilation failure for prog vrf_socket_lookup
  selftests/bpf: Add vrf_socket_lookup tests
  bpf: Fix bpf socket lookup from tc/xdp to respect socket VRF bindings
  bpf: Call __bpf_sk_lookup()/__bpf_skc_lookup() directly via TC hookpoint
  bpf: Factor out socket lookup functions for the TC hookpoint.
  selftests/bpf: Set the default value of consumer_cnt as 0
  selftests/bpf: Ensure that next_cpu() returns a valid CPU number
  selftests/bpf: Output the correct error code for pthread APIs
  selftests/bpf: Use producer_cnt to allocate local counter array
  xsk: Remove unused inline function xsk_buff_discard()
  bpf: Keep BPF_PROG_LOAD permission checks clear of validations
  bpf: Centralize permissions checks for all BPF map types
  bpf: Inline map creation logic in map_create() function
  bpf: Move unprivileged checks into map_create() and bpf_prog_load()
  bpf: Remove in_atomic() from bpf_link_put().
  selftests/bpf: Verify that check_ids() is used for scalars in regsafe()
  bpf: Verify scalar ids mapping in regsafe() using check_ids()
  selftests/bpf: Check if mark_chain_precision() follows scalar ids
  ...
====================

Link: https://lore.kernel.org/r/20230623211256.8409-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>