From acd516cfe2920006a5d2760c78bd2245d498023a Mon Sep 17 00:00:00 2001 From: Dean Deng Date: Wed, 24 Feb 2021 02:01:38 -0800 Subject: Add YAMA security module restrictions on ptrace(2). Restrict ptrace(2) according to the default configurations of the YAMA security module (mode 1), which is a common default among various Linux distributions. The new access checks only permit the tracer to proceed if one of the following conditions is met: a) The tracer is already attached to the tracee. b) The target is a descendant of the tracer. c) The target has explicitly given permission to the tracer through the PR_SET_PTRACER prctl. d) The tracer has CAP_SYS_PTRACE. See security/yama/yama_lsm.c for more details. Note that these checks are added to CanTrace, which is checked for PTRACE_ATTACH as well as some other operations, e.g., checking a process' memory layout through /proc/[pid]/mem. Since this patch adds restrictions to ptrace, it may break compatibility for applications run by non-root users that, for instance, rely on being able to trace processes that are not descended from the tracer (e.g., `gdb -p`). YAMA restrictions can be turned off by setting /proc/sys/kernel/yama/ptrace_scope to 0, or exceptions can be made on a per-process basis with the PR_SET_PTRACER prctl. Reported-by: syzbot+622822d8bca08c99e8c8@syzkaller.appspotmail.com PiperOrigin-RevId: 359237723 --- pkg/abi/linux/ptrace.go | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'pkg/abi/linux/ptrace.go') diff --git a/pkg/abi/linux/ptrace.go b/pkg/abi/linux/ptrace.go index 23e605ab2..db1c6a0d8 100644 --- a/pkg/abi/linux/ptrace.go +++ b/pkg/abi/linux/ptrace.go @@ -87,3 +87,9 @@ const ( PTRACE_O_EXITKILL = 1 << 20 PTRACE_O_SUSPEND_SECCOMP = 1 << 21 ) + +// YAMA ptrace_scope levels from security/yama/yama_lsm.c. +const ( + YAMA_SCOPE_DISABLED = 0 + YAMA_SCOPE_RELATIONAL = 1 +) -- cgit v1.2.3