linux-kernel - [for-linus][PATCH 06/17] ftrace: Do not let direct or IPMODIFY ftrace_ops be added to module and set trampolines

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200804205812.775534405@goodmis.org>
Date:   Tue, 04 Aug 2020 16:57:49 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Chengming Zhou <zhouchengming@...edance.com>,
        Muchun Song <songmuchun@...edance.com>
Subject: [for-linus][PATCH 06/17] ftrace: Do not let direct or IPMODIFY ftrace_ops be added to module
 and set trampolines

From: Chengming Zhou <zhouchengming@...edance.com>

When inserting a module, we find all ftrace_ops referencing it on the
ftrace_ops_list. But FTRACE_OPS_FL_DIRECT and FTRACE_OPS_FL_IPMODIFY
flags are special, and should not be set automatically. So warn and
skip ftrace_ops that have these two flags set and adding new code.
Also check if only one ftrace_ops references the module, in which case
we can use a trampoline as an optimization.

Link: https://lkml.kernel.org/r/20200728180554.65203-2-zhouchengming@bytedance.com

Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
Signed-off-by: Muchun Song <songmuchun@...edance.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 kernel/trace/ftrace.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d052f856f1cf..f433cb44300a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6199,9 +6199,17 @@ static int referenced_filters(struct dyn_ftrace *rec)
 
 	for (ops = ftrace_ops_list; ops != &ftrace_list_end; ops = ops->next) {
 		if (ops_references_rec(ops, rec)) {
+			if (WARN_ON_ONCE(ops->flags & FTRACE_OPS_FL_DIRECT))
+				continue;
+			if (WARN_ON_ONCE(ops->flags & FTRACE_OPS_FL_IPMODIFY))
+				continue;
 			cnt++;
 			if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
 				rec->flags |= FTRACE_FL_REGS;
+			if (cnt == 1 && ops->trampoline)
+				rec->flags |= FTRACE_FL_TRAMP;
+			else
+				rec->flags &= ~FTRACE_FL_TRAMP;
 		}
 	}
 
-- 
2.26.2