From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Yonghong Song <yhs@fb.com>, Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andriin@fb.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH AUTOSEL 5.6 075/606] bpf: Enforce returning 0 for fentry/fexit progs
Date: Mon, 8 Jun 2020 19:03:20 -0400 [thread overview]
Message-ID: <20200608231211.3363633-75-sashal@kernel.org> (raw)
In-Reply-To: <20200608231211.3363633-1-sashal@kernel.org>
From: Yonghong Song <yhs@fb.com>
commit e92888c72fbdc6f9d07b3b0604c012e81d7c0da7 upstream.
Currently, tracing/fentry and tracing/fexit prog
return values are not enforced. In trampoline codes,
the fentry/fexit prog return values are ignored.
Let us enforce it to be 0 to avoid confusion and
allows potential future extension.
This patch also explicitly added return value
checking for tracing/raw_tp, tracing/fmod_ret,
and freplace programs such that these program
return values can be anything. The purpose are
two folds:
1. to make it explicit about return value expectations
for these programs in verifier.
2. for tracing prog_type, if a future attach type
is added, the default is -ENOTSUPP which will
enforce to specify return value ranges explicitly.
Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200514053206.1298415-1-yhs@fb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/bpf/verifier.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1c53ccbd5b5d..c1bb5be530e9 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6498,6 +6498,22 @@ static int check_return_code(struct bpf_verifier_env *env)
return 0;
range = tnum_const(0);
break;
+ case BPF_PROG_TYPE_TRACING:
+ switch (env->prog->expected_attach_type) {
+ case BPF_TRACE_FENTRY:
+ case BPF_TRACE_FEXIT:
+ range = tnum_const(0);
+ break;
+ case BPF_TRACE_RAW_TP:
+ return 0;
+ default:
+ return -ENOTSUPP;
+ }
+ break;
+ case BPF_PROG_TYPE_EXT:
+ /* freplace program can return anything as its return value
+ * depends on the to-be-replaced kernel func or bpf program.
+ */
default:
return 0;
}
--
2.25.1
next prev parent reply other threads:[~2020-06-08 23:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200608231211.3363633-1-sashal@kernel.org>
2020-06-08 23:02 ` [PATCH AUTOSEL 5.6 006/606] bpf: Fix bug in mmap() implementation for BPF array map Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 068/606] bpf: Fix sk_psock refcnt leak when receiving message Sasha Levin
2020-06-08 23:03 ` Sasha Levin [this message]
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 076/606] selftests/bpf: Enforce returning 0 for fentry/fexit programs Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 077/606] bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 114/606] net/ena: Fix build warning in ena_xdp_set() Sasha Levin
2020-06-08 23:04 ` [PATCH AUTOSEL 5.6 141/606] bpf: Restrict bpf_probe_read{, str}() only to archs where they work Sasha Levin
2020-06-08 23:04 ` [PATCH AUTOSEL 5.6 142/606] bpf: Add bpf_probe_read_{user, kernel}_str() to do_refine_retval_range Sasha Levin
2020-06-08 23:04 ` [PATCH AUTOSEL 5.6 168/606] kbuild: Remove debug info from kallsyms linking Sasha Levin
2020-06-08 23:05 ` [PATCH AUTOSEL 5.6 198/606] flow_dissector: Drop BPF flow dissector prog ref on netns cleanup Sasha Levin
2020-06-08 23:05 ` [PATCH AUTOSEL 5.6 202/606] bpf: Prevent mmap()'ing read-only maps as writable Sasha Levin
2020-06-08 23:06 ` [PATCH AUTOSEL 5.6 243/606] net/tls: fix encryption error checking Sasha Levin
2020-06-08 23:06 ` [PATCH AUTOSEL 5.6 287/606] samples: bpf: Fix build error Sasha Levin
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