linux-stable.git/kernel/bpf/helpers.c, branch v5.18.2

bpf: Replace strncpy() with strscpy()

2022-03-08T06:04:33+00:00

Using strncpy() on NUL-terminated strings is considered deprecated[1].
Moreover, if the length of 'task->comm' is less than the destination buffer
size, strncpy() will NUL-pad the destination buffer, which is a needless
performance penalty.

Replacing strncpy() with strscpy() fixes all these issues.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings

Signed-off-by: Yuntao Wang 
Signed-off-by: Andrii Nakryiko 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20220304070408.233658-1-ytcoode@gmail.com

bpf: Cleanup comments

2022-02-23T23:17:51+00:00

Add leading space to spdx tag
Use // for spdx c file comment

Replacements
resereved to reserved
inbetween to in between
everytime to every time
intutivie to intuitive
currenct to current
encontered to encountered
referenceing to referencing
upto to up to
exectuted to executed

Signed-off-by: Tom Rix 
Signed-off-by: Andrii Nakryiko 
Acked-by: Song Liu 
Link: https://lore.kernel.org/bpf/20220220184055.3608317-1-trix@redhat.com

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2022-02-17T20:22:28+00:00

Fast path bpf marge for some -next work.

Signed-off-by: Jakub Kicinski

bpf: Emit bpf_timer in vmlinux BTF

2022-02-11T21:21:47+00:00

Currently the following code in check_and_init_map_value()
  *(struct bpf_timer *)(dst + map->timer_off) =
      (struct bpf_timer){};
can help generate bpf_timer definition in vmlinuxBTF.
But the code above may not zero the whole structure
due to anonymour members and that code will be replaced
by memset in the subsequent patch and
bpf_timer definition will disappear from vmlinuxBTF.
Let us emit the type explicitly so bpf program can continue
to use it from vmlinux.h.

Signed-off-by: Yonghong Song 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20220211194948.3141529-1-yhs@fb.com

bpf: make bpf_copy_from_user_task() gpl only

2022-01-31T20:44:37+00:00

access_process_vm() is exported by EXPORT_SYMBOL_GPL().

Signed-off-by: Kenta Tada 
Link: https://lore.kernel.org/r/20220128170906.21154-1-Kenta.Tada@sony.com
Signed-off-by: Alexei Starovoitov

bpf: Add bpf_copy_from_user_task() helper

2022-01-25T03:59:27+00:00

This adds a helper for bpf programs to read the memory of other
tasks.

As an example use case at Meta, we are using a bpf task iterator program
and this new helper to print C++ async stack traces for all threads of
a given process.

Signed-off-by: Kenny Yu 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/r/20220124185403.468466-3-kennyyu@fb.com
Signed-off-by: Alexei Starovoitov

bpf: Add MEM_RDONLY for helper args that are pointers to rdonly mem.

2021-12-18T21:27:41+00:00

Some helper functions may modify its arguments, for example,
bpf_d_path, bpf_get_stack etc. Previously, their argument types
were marked as ARG_PTR_TO_MEM, which is compatible with read-only
mem types, such as PTR_TO_RDONLY_BUF. Therefore it's legitimate,
but technically incorrect, to modify a read-only memory by passing
it into one of such helper functions.

This patch tags the bpf_args compatible with immutable memory with
MEM_RDONLY flag. The arguments that don't have this flag will be
only compatible with mutable memory types, preventing the helper
from modifying a read-only memory. The bpf_args that have
MEM_RDONLY are compatible with both mutable memory and immutable
memory.

Signed-off-by: Hao Luo 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20211217003152.48334-9-haoluo@google.com

bpf: Make per_cpu_ptr return rdonly PTR_TO_MEM.

2021-12-18T21:27:41+00:00

Tag the return type of {per, this}_cpu_ptr with RDONLY_MEM. The
returned value of this pair of helpers is kernel object, which
can not be updated by bpf programs. Previously these two helpers
return PTR_OT_MEM for kernel objects of scalar type, which allows
one to directly modify the memory. Now with RDONLY_MEM tagging,
the verifier will reject programs that write into RDONLY_MEM.

Fixes: 63d9b80dcf2c ("bpf: Introducte bpf_this_cpu_ptr()")
Fixes: eaa6bcb71ef6 ("bpf: Introduce bpf_per_cpu_ptr()")
Fixes: 4976b718c355 ("bpf: Introduce pseudo_btf_id")
Signed-off-by: Hao Luo 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20211217003152.48334-8-haoluo@google.com

bpf: Replace RET_XXX_OR_NULL with RET_XXX | PTR_MAYBE_NULL

2021-12-18T20:48:08+00:00

We have introduced a new type to make bpf_ret composable, by
reserving high bits to represent flags.

One of the flag is PTR_MAYBE_NULL, which indicates a pointer
may be NULL. When applying this flag to ret_types, it means
the returned value could be a NULL pointer. This patch
switches the qualified arg_types to use this flag.
The ret_types changed in this patch include:

1. RET_PTR_TO_MAP_VALUE_OR_NULL
2. RET_PTR_TO_SOCKET_OR_NULL
3. RET_PTR_TO_TCP_SOCK_OR_NULL
4. RET_PTR_TO_SOCK_COMMON_OR_NULL
5. RET_PTR_TO_ALLOC_MEM_OR_NULL
6. RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL
7. RET_PTR_TO_BTF_ID_OR_NULL

This patch doesn't eliminate the use of these names, instead
it makes them aliases to 'RET_PTR_TO_XXX | PTR_MAYBE_NULL'.

Signed-off-by: Hao Luo 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20211217003152.48334-4-haoluo@google.com

add missing bpf-cgroup.h includes

2021-12-16T22:57:09+00:00

We're about to break the cgroup-defs.h -> bpf-cgroup.h dependency,
make sure those who actually need more than the definition of
struct cgroup_bpf include bpf-cgroup.h explicitly.

Signed-off-by: Jakub Kicinski 
Signed-off-by: Alexei Starovoitov 
Acked-by: Tejun Heo 
Link: https://lore.kernel.org/bpf/20211216025538.1649516-3-kuba@kernel.org