Re: [PATCH v3 5/6] arm64: add support for uaccess logging
From: Peter Collingbourne
Date: Thu Dec 09 2021 - 16:44:31 EST
On Wed, Dec 8, 2021 at 1:49 AM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
>
> On Wed, 8 Dec 2021 at 05:48, Peter Collingbourne <pcc@xxxxxxxxxx> wrote:
> >
> > arm64 does not use CONFIG_GENERIC_ENTRY, so add the support for
> > uaccess logging directly to the architecture.
> >
> > Link: https://linux-review.googlesource.com/id/I88de539fb9c4a9d27fa8cccbe201a6e4382faf89
> > Signed-off-by: Peter Collingbourne <pcc@xxxxxxxxxx>
> > ---
> > arch/arm64/Kconfig | 1 +
> > arch/arm64/include/asm/thread_info.h | 7 ++++++-
> > arch/arm64/kernel/ptrace.c | 7 +++++++
> > arch/arm64/kernel/signal.c | 5 +++++
> > arch/arm64/kernel/syscall.c | 1 +
> > 5 files changed, 20 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index c4207cf9bb17..6023946abe4a 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -161,6 +161,7 @@ config ARM64
> > select HAVE_ARCH_THREAD_STRUCT_WHITELIST
> > select HAVE_ARCH_TRACEHOOK
> > select HAVE_ARCH_TRANSPARENT_HUGEPAGE
> > + select HAVE_ARCH_UACCESS_BUFFER
> > select HAVE_ARCH_VMAP_STACK
> > select HAVE_ARM_SMCCC
> > select HAVE_ASM_MODVERSIONS
> > diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
> > index e1317b7c4525..0461b36251ea 100644
> > --- a/arch/arm64/include/asm/thread_info.h
> > +++ b/arch/arm64/include/asm/thread_info.h
> > @@ -82,6 +82,8 @@ int arch_dup_task_struct(struct task_struct *dst,
> > #define TIF_SVE_VL_INHERIT 24 /* Inherit SVE vl_onexec across exec */
> > #define TIF_SSBD 25 /* Wants SSB mitigation */
> > #define TIF_TAGGED_ADDR 26 /* Allow tagged user addresses */
> > +#define TIF_UACCESS_BUFFER_ENTRY 27 /* thread has non-zero uaccess_desc_addr_addr */
> > +#define TIF_UACCESS_BUFFER_EXIT 28 /* thread has non-zero kcur */
> >
> > #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
> > #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
> > @@ -98,6 +100,8 @@ int arch_dup_task_struct(struct task_struct *dst,
> > #define _TIF_SVE (1 << TIF_SVE)
> > #define _TIF_MTE_ASYNC_FAULT (1 << TIF_MTE_ASYNC_FAULT)
> > #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL)
> > +#define _TIF_UACCESS_BUFFER_ENTRY (1 << TIF_UACCESS_BUFFER_ENTRY)
> > +#define _TIF_UACCESS_BUFFER_EXIT (1 << TIF_UACCESS_BUFFER_EXIT)
> >
> > #define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
> > _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
> > @@ -106,7 +110,8 @@ int arch_dup_task_struct(struct task_struct *dst,
> >
> > #define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
> > _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
> > - _TIF_SYSCALL_EMU)
> > + _TIF_SYSCALL_EMU | _TIF_UACCESS_BUFFER_ENTRY | \
> > + _TIF_UACCESS_BUFFER_EXIT)
> >
> > #ifdef CONFIG_SHADOW_CALL_STACK
> > #define INIT_SCS \
> > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> > index 88a9034fb9b5..283372eccaeb 100644
> > --- a/arch/arm64/kernel/ptrace.c
> > +++ b/arch/arm64/kernel/ptrace.c
> > @@ -29,6 +29,7 @@
> > #include <linux/regset.h>
> > #include <linux/tracehook.h>
> > #include <linux/elf.h>
> > +#include <linux/uaccess-buffer.h>
> >
> > #include <asm/compat.h>
> > #include <asm/cpufeature.h>
> > @@ -1854,6 +1855,9 @@ int syscall_trace_enter(struct pt_regs *regs)
> > if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
> > trace_sys_enter(regs, regs->syscallno);
> >
> > + if (flags & _TIF_UACCESS_BUFFER_ENTRY)
> > + uaccess_buffer_syscall_entry();
> > +
> > audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1],
> > regs->regs[2], regs->regs[3]);
> >
> > @@ -1866,6 +1870,9 @@ void syscall_trace_exit(struct pt_regs *regs)
> >
> > audit_syscall_exit(regs);
> >
> > + if (flags & _TIF_UACCESS_BUFFER_EXIT)
> > + uaccess_buffer_syscall_exit();
> > +
> > if (flags & _TIF_SYSCALL_TRACEPOINT)
> > trace_sys_exit(regs, syscall_get_return_value(current, regs));
> >
> > diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
> > index 8f6372b44b65..5bbd98e5c257 100644
> > --- a/arch/arm64/kernel/signal.c
> > +++ b/arch/arm64/kernel/signal.c
> > @@ -20,6 +20,7 @@
> > #include <linux/tracehook.h>
> > #include <linux/ratelimit.h>
> > #include <linux/syscalls.h>
> > +#include <linux/uaccess-buffer.h>
> >
> > #include <asm/daifflags.h>
> > #include <asm/debug-monitors.h>
> > @@ -919,6 +920,8 @@ static void do_signal(struct pt_regs *regs)
> >
> > void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
> > {
> > + bool uaccess_buffer_pending = uaccess_buffer_pre_exit_loop();
> > +
> > do {
> > if (thread_flags & _TIF_NEED_RESCHED) {
> > /* Unmask Debug and SError for the next task */
> > @@ -950,6 +953,8 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
> > local_daif_mask();
> > thread_flags = READ_ONCE(current_thread_info()->flags);
> > } while (thread_flags & _TIF_WORK_MASK);
> > +
> > + uaccess_buffer_post_exit_loop(uaccess_buffer_pending);
> > }
> >
> > unsigned long __ro_after_init signal_minsigstksz;
> > diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
> > index 50a0f1a38e84..d59022b594f2 100644
> > --- a/arch/arm64/kernel/syscall.c
> > +++ b/arch/arm64/kernel/syscall.c
> > @@ -7,6 +7,7 @@
> > #include <linux/ptrace.h>
> > #include <linux/randomize_kstack.h>
> > #include <linux/syscalls.h>
> > +#include <linux/uaccess-buffer.h>
>
> This looks strange... Does some other header miss this include?
This was left in unintentionally. I'll remove it in v4.
Peter