From: Yafang Shao <laoar.shao@gmail.com>
Date: Sun, 9 Jul 2023 02:56:24 +0000 (+0000)
Subject: bpf: Protect probed address based on kptr_restrict setting
X-Git-Tag: v6.6.17~4098^2~405^2~9^2~6
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f1a414537ecc18b5882a57045ce3e4a11e528290;p=platform%2Fkernel%2Flinux-rpi.git

bpf: Protect probed address based on kptr_restrict setting

The probed address can be accessed by userspace through querying the task
file descriptor (fd). However, it is crucial to adhere to the kptr_restrict
setting and refrain from exposing the address if it is not permitted.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230709025630.3735-5-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 1b3fa7b..249eb14 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1551,7 +1551,10 @@ int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
 	} else {
 		*symbol = NULL;
 		*probe_offset = 0;
-		*probe_addr = (unsigned long)tk->rp.kp.addr;
+		if (kallsyms_show_value(current_cred()))
+			*probe_addr = (unsigned long)tk->rp.kp.addr;
+		else
+			*probe_addr = 0;
 	}
 	return 0;
 }