linux-stable.git/include/linux/bpf.h, branch v6.1.53

bpf: Remove bpf trampoline selector

2023-07-19T14:21:05+00:00

[ Upstream commit 47e79cbeea4b3891ad476047f4c68543eb51c8e0 ]

After commit e21aa341785c ("bpf: Fix fexit trampoline."), the selector is only
used to indicate how many times the bpf trampoline image are updated and been
displayed in the trampoline ksym name. After the trampoline is freed, the
selector will start from 0 again. So the selector is a useless value to the
user. We can remove it.

If the user want to check whether the bpf trampoline image has been updated
or not, the user can compare the address. Each time the trampoline image is
updated, the address will change consequently. Jiri also pointed out another
issue that perf is still using the old name "bpf_trampoline_%lu", so this
change can fix the issue in perf.

Fixes: e21aa341785c ("bpf: Fix fexit trampoline.")
Signed-off-by: Yafang Shao 
Signed-off-by: Daniel Borkmann 
Acked-by: Song Liu 
Cc: Jiri Olsa 
Link: https://lore.kernel.org/bpf/ZFvOOlrmHiY9AgXE@krava
Link: https://lore.kernel.org/bpf/20230515130849.57502-3-laoar.shao@gmail.com
Signed-off-by: Sasha Levin

bpf: Zeroing allocated object from slab in bpf memory allocator

2023-03-10T08:33:06+00:00

[ Upstream commit 997849c4b969034e225153f41026657def66d286 ]

Currently the freed element in bpf memory allocator may be immediately
reused, for htab map the reuse will reinitialize special fields in map
value (e.g., bpf_spin_lock), but lookup procedure may still access
these special fields, and it may lead to hard-lockup as shown below:

 NMI backtrace for cpu 16
 CPU: 16 PID: 2574 Comm: htab.bin Tainted: G             L     6.1.0+ #1
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
 RIP: 0010:queued_spin_lock_slowpath+0x283/0x2c0
 ......
 Call Trace:
  
  copy_map_value_locked+0xb7/0x170
  bpf_map_copy_value+0x113/0x3c0
  __sys_bpf+0x1c67/0x2780
  __x64_sys_bpf+0x1c/0x20
  do_syscall_64+0x30/0x60
  entry_SYSCALL_64_after_hwframe+0x46/0xb0
 ......
  

For htab map, just like the preallocated case, these is no need to
initialize these special fields in map value again once these fields
have been initialized. For preallocated htab map, these fields are
initialized through __GFP_ZERO in bpf_map_area_alloc(), so do the
similar thing for non-preallocated htab in bpf memory allocator. And
there is no need to use __GFP_ZERO for per-cpu bpf memory allocator,
because __alloc_percpu_gfp() does it implicitly.

Fixes: 0fd7c5d43339 ("bpf: Optimize call_rcu in non-preallocated hash map.")
Signed-off-by: Hou Tao 
Link: https://lore.kernel.org/r/20230215082132.3856544-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

bpf: Fix offset calculation error in __copy_map_value and zero_map_value

2022-11-11T20:35:07+00:00

Function __copy_map_value and zero_map_value miscalculated copy offset,
resulting in possible copy of unwanted data to user or kernel.

Fix it.

Fixes: cc48755808c6 ("bpf: Add zero_map_value to zero map value with special fields")
Fixes: 4d7d7f69f4b1 ("bpf: Adapt copy_map_value for multiple offset case")
Signed-off-by: Xu Kuohai 
Signed-off-by: Andrii Nakryiko 
Acked-by: Kumar Kartikeya Dwivedi 
Link: https://lore.kernel.org/bpf/20221111125620.754855-1-xukuohai@huaweicloud.com

bpf: Convert BPF_DISPATCHER to use static_call() (not ftrace)

2022-11-04T22:13:57+00:00

The dispatcher function is currently abusing the ftrace __fentry__
call location for its own purposes -- this obviously gives trouble
when the dispatcher and ftrace are both in use.

A previous solution tried using __attribute__((patchable_function_entry()))
which works, except it is GCC-8+ only, breaking the build on the
earlier still supported compilers. Instead use static_call() -- which
has its own annotations and does not conflict with ftrace -- to
rewrite the dispatch function.

By using: return static_call()(ctx, insni, bpf_func) you get a perfect
forwarding tail call as function body (iow a single jmp instruction).
By having the default static_call() target be bpf_dispatcher_nop_func()
it retains the default behaviour (an indirect call to the argument
function). Only once a dispatcher program is attached is the target
rewritten to directly call the JIT'ed image.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Daniel Borkmann 
Tested-by: Björn Töpel 
Tested-by: Jiri Olsa 
Acked-by: Björn Töpel 
Acked-by: Jiri Olsa 
Link: https://lkml.kernel.org/r/Y1/oBlK0yFk5c/Im@hirez.programming.kicks-ass.net
Link: https://lore.kernel.org/bpf/20221103120647.796772565@infradead.org

bpf: Revert ("Fix dispatcher patchable function entry to 5 bytes nop")

2022-11-04T22:13:08+00:00

Because __attribute__((patchable_function_entry)) is only available
since GCC-8 this solution fails to build on the minimum required GCC
version.

Undo these changes so we might try again -- without cluttering up the
patches with too many changes.

This is an almost complete revert of:

  dbe69b299884 ("bpf: Fix dispatcher patchable function entry to 5 bytes nop")
  ceea991a019c ("bpf: Move bpf_dispatcher function out of ftrace locations")

(notably the arch/x86/Kconfig hunk is kept).

Reported-by: David Laight 
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Daniel Borkmann 
Tested-by: Björn Töpel 
Tested-by: Jiri Olsa 
Acked-by: Björn Töpel 
Acked-by: Jiri Olsa 
Link: https://lkml.kernel.org/r/439d8dc735bb4858875377df67f1b29a@AcuMS.aculab.com
Link: https://lore.kernel.org/bpf/20221103120647.728830733@infradead.org

bpf: Fix dispatcher patchable function entry to 5 bytes nop

2022-10-21T01:57:51+00:00

The patchable_function_entry(5) might output 5 single nop
instructions (depends on toolchain), which will clash with
bpf_arch_text_poke check for 5 bytes nop instruction.

Adding early init call for dispatcher that checks and change
the patchable entry into expected 5 nop instruction if needed.

There's no need to take text_mutex, because we are using it
in early init call which is called at pre-smp time.

Fixes: ceea991a019c ("bpf: Move bpf_dispatcher function out of ftrace locations")
Signed-off-by: Jiri Olsa 
Acked-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/20221018075934.574415-1-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov

bpf: Add __bpf_prog_{enter,exit}_struct_ops for struct_ops trampoline

2022-09-29T16:25:47+00:00

The struct_ops prog is to allow using bpf to implement the functions in
a struct (eg. kernel module).  The current usage is to implement the
tcp_congestion.  The kernel does not call the tcp-cc's ops (ie.
the bpf prog) in a recursive way.

The struct_ops is sharing the tracing-trampoline's enter/exit
function which tracks prog->active to avoid recursion.  It is
needed for tracing prog.  However, it turns out the struct_ops
bpf prog will hit this prog->active and unnecessarily skipped
running the struct_ops prog.  eg.  The '.ssthresh' may run in_task()
and then interrupted by softirq that runs the same '.ssthresh'.
Skip running the '.ssthresh' will end up returning random value
to the caller.

The patch adds __bpf_prog_{enter,exit}_struct_ops for the
struct_ops trampoline.  They do not track the prog->active
to detect recursion.

One exception is when the tcp_congestion's '.init' ops is doing
bpf_setsockopt(TCP_CONGESTION) and then recurs to the same
'.init' ops.  This will be addressed in the following patches.

Fixes: ca06f55b9002 ("bpf: Add per-program recursion prevention mechanism")
Signed-off-by: Martin KaFai Lau 
Link: https://lore.kernel.org/r/20220929070407.965581-2-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov

bpf: Parameterize task iterators.

2022-09-28T23:29:47+00:00

Allow creating an iterator that loops through resources of one
thread/process.

People could only create iterators to loop through all resources of
files, vma, and tasks in the system, even though they were interested
in only the resources of a specific task or process.  Passing the
additional parameters, people can now create an iterator to go
through all resources or only the resources of a task.

Signed-off-by: Kui-Feng Lee 
Signed-off-by: Andrii Nakryiko 
Acked-by: Yonghong Song 
Acked-by: Martin KaFai Lau 
Link: https://lore.kernel.org/bpf/20220926184957.208194-2-kuifeng@fb.com

bpf: Enforce W^X for bpf trampoline

2022-09-27T03:40:43+00:00

Mark the trampoline as RO+X after arch_prepare_bpf_trampoline, so that
the trampoine follows W^X rule strictly. This will turn off warnings like

CPA refuse W^X violation: 8000000000000163 -> 0000000000000163 range: ...

Also remove bpf_jit_alloc_exec_page(), since it is not used any more.

Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/20220926184739.3512547-3-song@kernel.org
Signed-off-by: Alexei Starovoitov

bpf: use bpf_prog_pack for bpf_dispatcher

2022-09-27T03:40:43+00:00

Allocate bpf_dispatcher with bpf_prog_pack_alloc so that bpf_dispatcher
can share pages with bpf programs.

arch_prepare_bpf_dispatcher() is updated to provide a RW buffer as working
area for arch code to write to.

This also fixes CPA W^X warnning like:

CPA refuse W^X violation: 8000000000000163 -> 0000000000000163 range: ...

Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/20220926184739.3512547-2-song@kernel.org
Signed-off-by: Alexei Starovoitov