From: Gregory Price <gourry.memverge@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: linux-doc@vger.kernel.org, oleg@redhat.com, avagin@gmail.com,
peterz@infradead.org, luto@kernel.org, krisman@collabora.com,
tglx@linutronix.de, corbet@lwn.net, shuah@kernel.org,
Gregory Price <gregory.price@memverge.com>
Subject: [PATCH v6 1/2] ptrace,syscall_user_dispatch: Implement Syscall User Dispatch Suspension
Date: Tue, 24 Jan 2023 21:51:25 -0500 [thread overview]
Message-ID: <20230125025126.787431-2-gregory.price@memverge.com> (raw)
In-Reply-To: <20230125025126.787431-1-gregory.price@memverge.com>
Adds PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH to ptrace options, and
modify Syscall User Dispatch to suspend interception when enabled.
This is modeled after the SUSPEND_SECCOMP feature, which suspends
SECCOMP interposition. Without doing this, software like CRIU will
inject system calls into a process and be intercepted by Syscall
User Dispatch, either causing a crash (due to blocked signals) or
the delivery of those signals to a ptracer (not the intended behavior).
Since Syscall User Dispatch is not a privileged feature, a check
for permissions is not required, however attempting to set this
option when CONFIG_CHECKPOINT_RESTORE it not supported should be
disallowed, as its intended use is checkpoint/resume.
Signed-off-by: Gregory Price <gregory.price@memverge.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
---
include/linux/ptrace.h | 2 ++
include/uapi/linux/ptrace.h | 6 +++++-
kernel/entry/syscall_user_dispatch.c | 5 +++++
kernel/ptrace.c | 4 ++++
4 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index eaaef3ffec22..461ae5c99d57 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -45,6 +45,8 @@ extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
#define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
#define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
+#define PT_SUSPEND_SYSCALL_USER_DISPATCH \
+ (PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH << PT_OPT_FLAG_SHIFT)
extern long arch_ptrace(struct task_struct *child, long request,
unsigned long addr, unsigned long data);
diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
index 195ae64a8c87..ba9e3f19a22c 100644
--- a/include/uapi/linux/ptrace.h
+++ b/include/uapi/linux/ptrace.h
@@ -146,9 +146,13 @@ struct ptrace_rseq_configuration {
/* eventless options */
#define PTRACE_O_EXITKILL (1 << 20)
#define PTRACE_O_SUSPEND_SECCOMP (1 << 21)
+#define PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH (1 << 22)
#define PTRACE_O_MASK (\
- 0x000000ff | PTRACE_O_EXITKILL | PTRACE_O_SUSPEND_SECCOMP)
+ 0x000000ff | \
+ PTRACE_O_EXITKILL | \
+ PTRACE_O_SUSPEND_SECCOMP | \
+ PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH)
#include <asm/ptrace.h>
diff --git a/kernel/entry/syscall_user_dispatch.c b/kernel/entry/syscall_user_dispatch.c
index 0b6379adff6b..b5ec75164805 100644
--- a/kernel/entry/syscall_user_dispatch.c
+++ b/kernel/entry/syscall_user_dispatch.c
@@ -8,6 +8,7 @@
#include <linux/uaccess.h>
#include <linux/signal.h>
#include <linux/elf.h>
+#include <linux/ptrace.h>
#include <linux/sched/signal.h>
#include <linux/sched/task_stack.h>
@@ -36,6 +37,10 @@ bool syscall_user_dispatch(struct pt_regs *regs)
struct syscall_user_dispatch *sd = ¤t->syscall_dispatch;
char state;
+ if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
+ unlikely(current->ptrace & PT_SUSPEND_SYSCALL_USER_DISPATCH))
+ return false;
+
if (likely(instruction_pointer(regs) - sd->offset < sd->len))
return false;
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 54482193e1ed..a348b68d07a2 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -370,6 +370,10 @@ static int check_ptrace_options(unsigned long data)
if (data & ~(unsigned long)PTRACE_O_MASK)
return -EINVAL;
+ if (unlikely(data & PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH) &&
+ (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE)))
+ return -EINVAL;
+
if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) {
if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) ||
!IS_ENABLED(CONFIG_SECCOMP))
--
2.39.0
next prev parent reply other threads:[~2023-01-25 2:51 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-25 2:51 [PATCH v6 0/2] Gregory Price
2023-01-25 2:51 ` Gregory Price [this message]
2023-01-26 0:30 ` [PATCH v6 1/2] ptrace,syscall_user_dispatch: Implement Syscall User Dispatch Suspension Oleg Nesterov
2023-01-26 1:30 ` Gregory Price
2023-01-26 4:43 ` Gregory Price
[not found] ` <CANaxB-xn0wW5xA_CT7bA5=jig+td__EDKPBWSpZdfgMgVOezCg@mail.gmail.com>
2023-01-26 5:26 ` Gregory Price
2023-01-26 15:10 ` Oleg Nesterov
2023-01-26 18:09 ` Andrei Vagin
2023-01-26 15:07 ` Oleg Nesterov
2023-01-26 17:45 ` Andrei Vagin
2023-01-26 17:52 ` Gregory Price
2023-01-26 18:30 ` Andrei Vagin
2023-01-26 18:30 ` Oleg Nesterov
2023-01-26 18:46 ` Gregory Price
2023-01-26 18:53 ` Andrei Vagin
2023-01-26 19:01 ` Gregory Price
2023-01-25 2:51 ` [PATCH v6 2/2] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration Gregory Price
2023-01-25 7:14 ` kernel test robot
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