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Date: Mon, 12 Dec 2022 00:16:05 +0200 From: david.keisarschm@...l.huji.ac.il To: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, John Fastabend <john.fastabend@...il.com>, Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>, KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...gle.com>, Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com> Cc: David <david.keisarschm@...l.huji.ac.il>, aksecurity@...il.com, ilay.bahat1@...il.com, bpf@...r.kernel.org, linux-kernel@...r.kernel.org, netdev@...r.kernel.org Subject: [PATCH 2/5] Replace invocation of weak PRNG in kernel/bpf/core.c From: David <david.keisarschm@...l.huji.ac.il> We changed the invocation of prandom_u32_state to get_random_u32. We deleted the maintained state, which was a CPU-variable, since get_random_u32 maintains its own CPU-variable. We also deleted the state initializer, since it is not needed anymore. Signed-off-by: David <david.keisarschm@...l.huji.ac.il> --- include/linux/bpf.h | 1 - kernel/bpf/core.c | 13 +------------ kernel/bpf/verifier.c | 2 -- net/core/filter.c | 1 - 4 files changed, 1 insertion(+), 16 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c1bd1bd10..0689520b9 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2572,7 +2572,6 @@ const struct bpf_func_proto *tracing_prog_func_proto( enum bpf_func_id func_id, const struct bpf_prog *prog); /* Shared helpers among cBPF and eBPF. */ -void bpf_user_rnd_init_once(void); u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5); u64 bpf_get_raw_cpu_id(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 4cb5421d9..a6f06894e 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2579,13 +2579,6 @@ void bpf_prog_free(struct bpf_prog *fp) } EXPORT_SYMBOL_GPL(bpf_prog_free); -/* RNG for unpriviledged user space with separated state from prandom_u32(). */ -static DEFINE_PER_CPU(struct rnd_state, bpf_user_rnd_state); - -void bpf_user_rnd_init_once(void) -{ - prandom_init_once(&bpf_user_rnd_state); -} BPF_CALL_0(bpf_user_rnd_u32) { @@ -2595,12 +2588,8 @@ BPF_CALL_0(bpf_user_rnd_u32) * transformations. Register assignments from both sides are * different, f.e. classic always sets fn(ctx, A, X) here. */ - struct rnd_state *state; u32 res; - - state = &get_cpu_var(bpf_user_rnd_state); - res = predictable_rng_prandom_u32_state(state); - put_cpu_var(bpf_user_rnd_state); + res = get_random_u32(); return res; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 264b3dc71..9f22fb3fa 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14049,8 +14049,6 @@ static int do_misc_fixups(struct bpf_verifier_env *env) if (insn->imm == BPF_FUNC_get_route_realm) prog->dst_needed = 1; - if (insn->imm == BPF_FUNC_get_prandom_u32) - bpf_user_rnd_init_once(); if (insn->imm == BPF_FUNC_override_return) prog->kprobe_override = 1; if (insn->imm == BPF_FUNC_tail_call) { diff --git a/net/core/filter.c b/net/core/filter.c index bb0136e7a..7a595ac00 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -443,7 +443,6 @@ static bool convert_bpf_extensions(struct sock_filter *fp, break; case SKF_AD_OFF + SKF_AD_RANDOM: *insn = BPF_EMIT_CALL(bpf_user_rnd_u32); - bpf_user_rnd_init_once(); break; } break; -- 2.38.0
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