diff options
| author | Dean Deng <deandeng@google.com> | 2021-02-24 02:01:38 -0800 |
|---|---|---|
| committer | gVisor bot <gvisor-bot@google.com> | 2021-02-24 02:03:16 -0800 |
| commit | acd516cfe2920006a5d2760c78bd2245d498023a (patch) | |
| tree | a60c57de55b821e6dd33bf2cfa37feb09903c2a2 /pkg/abi/linux | |
| parent | 6e000d3424c0eed685483f54348c6b0a752a0435 (diff) | |
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
Diffstat (limited to 'pkg/abi/linux')
| -rw-r--r-- | pkg/abi/linux/prctl.go | 5 | ||||
| -rw-r--r-- | pkg/abi/linux/ptrace.go | 6 |
2 files changed, 11 insertions, 0 deletions
diff --git a/pkg/abi/linux/prctl.go b/pkg/abi/linux/prctl.go index 391cfaa1c..41118c3b4 100644 --- a/pkg/abi/linux/prctl.go +++ b/pkg/abi/linux/prctl.go @@ -144,6 +144,11 @@ const ( // PR_MPX_DISABLE_MANAGEMENT disables kernel management of Memory // Protection eXtensions (MPX) bounds tables. PR_MPX_DISABLE_MANAGEMENT = 44 + + // PR_SET_PTRACER allows a specific process (or any, if PR_SET_PTRACER_ANY is + // specified) to ptrace the current task. + PR_SET_PTRACER = 0x59616d61 + PR_SET_PTRACER_ANY = -1 ) // From <asm/prctl.h> 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 +) |