[PATCH 12/19] arm64: ptrace: handle ptrace_request differently for aarch32 and ilp32

Yury Norov
2016-06-17T23:54:21Z

Here new aarch32 ptrace syscall handler is introsuced to avoid run-time
detection of the task type.

Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
---
arch/arm64/include/asm/unistd32.h | 2 +-
arch/arm64/kernel/ptrace.c | 50 ++++++++++++++++++++++++++++++++++++++-
arch/arm64/kernel/sys32.c | 1 +
include/linux/ptrace.h | 6 +++++
kernel/ptrace.c | 10 ++++----
5 files changed, 62 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
index b7e8ef1..6da7cbd 100644
--- a/arch/arm64/include/asm/unistd32.h
+++ b/arch/arm64/include/asm/unistd32.h
@@ -74,7 +74,7 @@ __SYSCALL(__NR_getuid, sys_getuid16)
/* 25 was sys_stime */
__SYSCALL(25, sys_ni_syscall)
#define __NR_ptrace 26
-__SYSCALL(__NR_ptrace, compat_sys_ptrace)
+__SYSCALL(__NR_ptrace, compat_sys_aarch32_ptrace)
/* 27 was sys_alarm */
__SYSCALL(27, sys_ni_syscall)
/* 28 was sys_fstat */
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 38a09338..a861105 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -29,6 +29,7 @@
#include <linux/user.h>
#include <linux/seccomp.h>
#include <linux/security.h>
+#include <linux/syscalls.h>
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/uaccess.h>
@@ -1114,7 +1115,7 @@ static int compat_ptrace_sethbpregs(struct task_struct *tsk, compat_long_t num,
}
#endif /* CONFIG_HAVE_HW_BREAKPOINT */

-long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
+static long compat_a32_ptrace(struct task_struct *child, compat_long_t request,
compat_ulong_t caddr, compat_ulong_t cdata)
{
unsigned long addr = caddr;
@@ -1191,8 +1192,55 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,

return ret;
}
+
+COMPAT_SYSCALL_DEFINE4(aarch32_ptrace, compat_long_t, request, compat_long_t, pid,
+ compat_long_t, addr, compat_long_t, data)
+{
+ struct task_struct *child;
+ long ret;
+
+ if (request == PTRACE_TRACEME) {
+ ret = ptrace_traceme();
+ goto out;
+ }
+
+ child = ptrace_get_task_struct(pid);
+ if (IS_ERR(child)) {
+ ret = PTR_ERR(child);
+ goto out;
+ }
+
+ if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
+ ret = ptrace_attach(child, request, addr, data);
+ goto out_put_task_struct;
+ }
+
+ ret = ptrace_check_attach(child, request == PTRACE_KILL ||
+ request == PTRACE_INTERRUPT);
+ if (!ret) {
+ ret = compat_a32_ptrace(child, request, addr, data);
+ if (ret || request != PTRACE_DETACH)
+ ptrace_unfreeze_traced(child);
+ }
+
+ out_put_task_struct:
+ put_task_struct(child);
+ out:
+ return ret;
+}
+
#endif /* CONFIG_AARCH32_EL0 */

+#ifdef CONFIG_COMPAT
+
+long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
+ compat_ulong_t caddr, compat_ulong_t cdata)
+{
+ return compat_ptrace_request(child, request, caddr, cdata);
+}
+
+#endif /* CONFIG_COMPAT */
+
const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
#ifdef CONFIG_AARCH32_EL0
diff --git a/arch/arm64/kernel/sys32.c b/arch/arm64/kernel/sys32.c
index a40b134..3752443 100644
--- a/arch/arm64/kernel/sys32.c
+++ b/arch/arm64/kernel/sys32.c
@@ -38,6 +38,7 @@ asmlinkage long compat_sys_fadvise64_64_wrapper(void);
asmlinkage long compat_sys_sync_file_range2_wrapper(void);
asmlinkage long compat_sys_fallocate_wrapper(void);
asmlinkage long compat_sys_mmap2_wrapper(void);
+asmlinkage long compat_sys_aarch32_ptrace(void);

#undef __SYSCALL
#define __SYSCALL(nr, sym) [nr] = sym,
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index 504c98a..75887a0 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -97,6 +97,12 @@ int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
unsigned long data);
int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
unsigned long data);
+int ptrace_traceme(void);
+struct task_struct *ptrace_get_task_struct(pid_t pid);
+int ptrace_attach(struct task_struct *task, long request,
+ unsigned long addr, unsigned long flags);
+int ptrace_check_attach(struct task_struct *child, bool ignore_state);
+void ptrace_unfreeze_traced(struct task_struct *task);

/**
* ptrace_parent - return the task that is tracing the given task
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index d49bfa1..cadf24c 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -136,7 +136,7 @@ static bool ptrace_freeze_traced(struct task_struct *task)
return ret;
}

-static void ptrace_unfreeze_traced(struct task_struct *task)
+void ptrace_unfreeze_traced(struct task_struct *task)
{
if (task->state != __TASK_TRACED)
return;
@@ -168,7 +168,7 @@ static void ptrace_unfreeze_traced(struct task_struct *task)
* RETURNS:
* 0 on success, -ESRCH if %child is not ready.
*/
-static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
+int ptrace_check_attach(struct task_struct *child, bool ignore_state)
{
int ret = -ESRCH;

@@ -292,7 +292,7 @@ bool ptrace_may_access(struct task_struct *task, unsigned int mode)
return !err;
}

-static int ptrace_attach(struct task_struct *task, long request,
+int ptrace_attach(struct task_struct *task, long request,
unsigned long addr,
unsigned long flags)
{
@@ -406,7 +406,7 @@ out:
* Performs checks and sets PT_PTRACED.
* Should be used by all ptrace implementations for PTRACE_TRACEME.
*/
-static int ptrace_traceme(void)
+ int ptrace_traceme(void)
{
int ret = -EPERM;

@@ -1056,7 +1056,7 @@ int ptrace_request(struct task_struct *child, long request,
return ret;
}

-static struct task_struct *ptrace_get_task_struct(pid_t pid)
+struct task_struct *ptrace_get_task_struct(pid_t pid)
{
struct task_struct *child;

--
2.7.4