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author | Alexei Starovoitov <ast@kernel.org> | 2020-03-05 00:41:06 +0300 |
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committer | Alexei Starovoitov <ast@kernel.org> | 2020-03-05 00:47:16 +0300 |
commit | 9ce6010290587f4b0c57e2819481bd5ba9668349 (patch) | |
tree | 7e9836d1926fce0e65362a47474fed446ea75f8c /arch/riscv/net | |
parent | cc6fa771024ffdb428bdf25a94309cf21e8ef1b9 (diff) | |
parent | 3d08b6f29cf33aeaf301553d8d3805f0aa609df7 (diff) | |
download | linux-9ce6010290587f4b0c57e2819481bd5ba9668349.tar.xz |
Merge branch 'bpf_modify_ret'
KP Singh says:
====================
v3 -> v4:
* Fix a memory leak noticed by Daniel.
v2 -> v3:
* bpf_trampoline_update_progs -> bpf_trampoline_get_progs + const
qualification.
* Typos in commit messages.
* Added Andrii's Acks.
v1 -> v2:
* Adressed Andrii's feedback.
* Fixed a bug that Alexei noticed about nop generation.
* Rebase.
This was brought up in the KRSI v4 discussion and found to be useful
both for security and tracing programs.
https://lore.kernel.org/bpf/20200225193108.GB22391@chromium.org/
The modify_return programs are allowed for security hooks (with an
extra CAP_MAC_ADMIN check) and functions whitelisted for error
injection (ALLOW_ERROR_INJECTION).
The "security_" check is expected to be cleaned up with the KRSI patch
series.
Here is an example of how a fmod_ret program behaves:
int func_to_be_attached(int a, int b)
{ <--- do_fentry
do_fmod_ret:
<update ret by calling fmod_ret>
if (ret != 0)
goto do_fexit;
original_function:
<side_effects_happen_here>
} <--- do_fexit
ALLOW_ERROR_INJECTION(func_to_be_attached, ERRNO)
The fmod_ret program attached to this function can be defined as:
SEC("fmod_ret/func_to_be_attached")
int BPF_PROG(func_name, int a, int b, int ret)
{
// This will skip the original function logic.
return -1;
}
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch/riscv/net')
0 files changed, 0 insertions, 0 deletions