Re: [PATCH v3 5/6] arm64: add support for uaccess logging

On Wed, Dec 8, 2021 at 1:49 AM Dmitry Vyukov [off-list ref] wrote:

On Wed, 8 Dec 2021 at 05:48, Peter Collingbourne [off-list ref] wrote:

quoted

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 <redacted>
---
 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

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel