122 lines
4.2 KiB
Diff
122 lines
4.2 KiB
Diff
From 897560fd00e1add63a9973c31fc437b006855680 Mon Sep 17 00:00:00 2001
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From: Sergio Lopez <[email protected]>
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Date: Tue, 8 Oct 2024 11:24:25 +0200
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Subject: [PATCH] Enable 64 bit processes to use compat input syscalls
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The compat variant of input syscalls is only enabled for 32 bit
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tasks, but in some cases, such as userspace emulation, it's useful to
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enable that variant for 64 bit processes.
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Here we introduce the PR_[GET|SET]_COMPAT_INPUT prctl to allow 64 bit
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tasks to opt-in for compat input syscalls.
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Signed-off-by: Sergio Lopez <[email protected]>
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---
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drivers/input/input-compat.c | 6 +++---
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drivers/input/input-compat.h | 2 +-
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include/linux/sched.h | 5 +++++
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include/uapi/linux/prctl.h | 5 +++++
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kernel/sys.c | 15 +++++++++++++++
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5 files changed, 29 insertions(+), 4 deletions(-)
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diff --git a/drivers/input/input-compat.c b/drivers/input/input-compat.c
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index 2ccd3eedbd6733..abb8cfb99d6cf9 100644
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--- a/drivers/input/input-compat.c
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+++ b/drivers/input/input-compat.c
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@@ -14,7 +14,7 @@
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int input_event_from_user(const char __user *buffer,
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struct input_event *event)
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{
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- if (in_compat_syscall() && !COMPAT_USE_64BIT_TIME) {
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+ if (current->compat_input || (in_compat_syscall() && !COMPAT_USE_64BIT_TIME)) {
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struct input_event_compat compat_event;
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if (copy_from_user(&compat_event, buffer,
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@@ -38,7 +38,7 @@ int input_event_from_user(const char __user *buffer,
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int input_event_to_user(char __user *buffer,
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const struct input_event *event)
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{
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- if (in_compat_syscall() && !COMPAT_USE_64BIT_TIME) {
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+ if (current->compat_input || (in_compat_syscall() && !COMPAT_USE_64BIT_TIME)) {
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struct input_event_compat compat_event;
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compat_event.sec = event->input_event_sec;
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@@ -62,7 +62,7 @@ int input_event_to_user(char __user *buffer,
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int input_ff_effect_from_user(const char __user *buffer, size_t size,
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struct ff_effect *effect)
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{
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- if (in_compat_syscall()) {
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+ if (current->compat_input || (in_compat_syscall() && !COMPAT_USE_64BIT_TIME)) {
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struct ff_effect_compat *compat_effect;
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if (size != sizeof(struct ff_effect_compat))
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diff --git a/drivers/input/input-compat.h b/drivers/input/input-compat.h
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index 3b7bb12b023bc6..e78c0492ce0d36 100644
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--- a/drivers/input/input-compat.h
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+++ b/drivers/input/input-compat.h
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@@ -53,7 +53,7 @@ struct ff_effect_compat {
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static inline size_t input_event_size(void)
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{
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- return (in_compat_syscall() && !COMPAT_USE_64BIT_TIME) ?
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+ return (current->compat_input || (in_compat_syscall() && !COMPAT_USE_64BIT_TIME)) ?
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sizeof(struct input_event_compat) : sizeof(struct input_event);
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}
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diff --git a/include/linux/sched.h b/include/linux/sched.h
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index 77f01ac385f7a5..01125573065ecd 100644
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--- a/include/linux/sched.h
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+++ b/include/linux/sched.h
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@@ -1535,6 +1535,11 @@ struct task_struct {
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#ifdef CONFIG_USER_EVENTS
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struct user_event_mm *user_event_mm;
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#endif
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+ /*
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+ * Whether the task wants to use compat input syscalls even if it's
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+ * a 64-bit process.
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+ */
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+ bool compat_input;
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/*
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* New fields for task_struct should be added above here, so that
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diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
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index 961216093f11ab..86fca7d168cc66 100644
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--- a/include/uapi/linux/prctl.h
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+++ b/include/uapi/linux/prctl.h
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@@ -311,4 +311,9 @@ struct prctl_mm_map {
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# define PR_SET_MEM_MODEL_DEFAULT 0
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# define PR_SET_MEM_MODEL_TSO 1
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+#define PR_GET_COMPAT_INPUT 0x63494e50
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+#define PR_SET_COMPAT_INPUT 0x43494e50
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+# define PR_SET_COMPAT_INPUT_DISABLE 0
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+# define PR_SET_COMPAT_INPUT_ENABLE 1
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+
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#endif /* _LINUX_PRCTL_H */
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diff --git a/kernel/sys.c b/kernel/sys.c
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index 2db751ce25a260..1be74620b0b659 100644
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--- a/kernel/sys.c
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+++ b/kernel/sys.c
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@@ -2768,6 +2768,21 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
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return -EINVAL;
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error = arch_prctl_mem_model_set(me, arg2);
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break;
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+ case PR_GET_COMPAT_INPUT:
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+ if (arg2 || arg3 || arg4 || arg5)
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+ return -EINVAL;
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+ error = current->compat_input;
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+ break;
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+ case PR_SET_COMPAT_INPUT:
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+ if (arg3 || arg4 || arg5)
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+ return -EINVAL;
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+ if (arg2 == PR_SET_COMPAT_INPUT_DISABLE)
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+ current->compat_input = false;
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+ else if (arg2 == PR_SET_COMPAT_INPUT_ENABLE)
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+ current->compat_input = true;
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+ else
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+ return -EINVAL;
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+ break;
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default:
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error = -EINVAL;
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break;
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