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Subject[PATCH -mm 2/4] ptrace: compat_ptrace_request siginfo
Date

This adds support for PTRACE_GETSIGINFO and PTRACE_SETSIGINFO in
compat_ptrace_request. It relies on existing arch definitions for
copy_siginfo_to_user32 and copy_siginfo_from_user32.

On powerpc, this fixes a longstanding regression of 32-bit ptrace
calls on 64-bit kernels vs native calls (64-bit calls or 32-bit
kernels). This can be seen in a 32-bit call using PTRACE_GETSIGINFO
to examine e.g. siginfo_t.si_addr from a signal that sets it.
(This was broken as of 2.6.24 and, I presume, many or all prior versions.)

Signed-off-by: Roland McGrath <roland@redhat.com>
---
kernel/ptrace.c | 48 +++++++++++++++++++++++++++++++++++-------------
1 files changed, 35 insertions(+), 13 deletions(-)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index fdb34e8..67e392e 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -323,9 +323,8 @@ static int ptrace_setoptions(struct task_struct *child, long data)
return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
}

-static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data)
+static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
{
- siginfo_t lastinfo;
int error = -ESRCH;

read_lock(&tasklist_lock);
@@ -333,31 +332,25 @@ static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data)
error = -EINVAL;
spin_lock_irq(&child->sighand->siglock);
if (likely(child->last_siginfo != NULL)) {
- lastinfo = *child->last_siginfo;
+ *info = *child->last_siginfo;
error = 0;
}
spin_unlock_irq(&child->sighand->siglock);
}
read_unlock(&tasklist_lock);
- if (!error)
- return copy_siginfo_to_user(data, &lastinfo);
return error;
}

-static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data)
+static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
{
- siginfo_t newinfo;
int error = -ESRCH;

- if (copy_from_user(&newinfo, data, sizeof (siginfo_t)))
- return -EFAULT;
-
read_lock(&tasklist_lock);
if (likely(child->sighand != NULL)) {
error = -EINVAL;
spin_lock_irq(&child->sighand->siglock);
if (likely(child->last_siginfo != NULL)) {
- *child->last_siginfo = newinfo;
+ *child->last_siginfo = *info;
error = 0;
}
spin_unlock_irq(&child->sighand->siglock);
@@ -424,6 +417,7 @@ int ptrace_request(struct task_struct *child, long request,
long addr, long data)
{
int ret = -EIO;
+ siginfo_t siginfo;

switch (request) {
case PTRACE_PEEKTEXT:
@@ -442,12 +436,22 @@ int ptrace_request(struct task_struct *child, long request,
case PTRACE_GETEVENTMSG:
ret = put_user(child->ptrace_message, (unsigned long __user *) data);
break;
+
case PTRACE_GETSIGINFO:
- ret = ptrace_getsiginfo(child, (siginfo_t __user *) data);
+ ret = ptrace_getsiginfo(child, &siginfo);
+ if (!ret)
+ ret = copy_siginfo_to_user((siginfo_t __user *) data,
+ &siginfo);
break;
+
case PTRACE_SETSIGINFO:
- ret = ptrace_setsiginfo(child, (siginfo_t __user *) data);
+ if (copy_from_user(&siginfo, (siginfo_t __user *) data,
+ sizeof siginfo))
+ ret = -EFAULT;
+ else
+ ret = ptrace_setsiginfo(child, &siginfo);
break;
+
case PTRACE_DETACH: /* detach a process that was attached. */
ret = ptrace_detach(child, data);
break;
@@ -616,6 +620,7 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
{
compat_ulong_t __user *datap = compat_ptr(data);
compat_ulong_t word;
+ siginfo_t siginfo;
int ret;

switch (request) {
@@ -638,6 +643,23 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
ret = put_user((compat_ulong_t) child->ptrace_message, datap);
break;

+ case PTRACE_GETSIGINFO:
+ ret = ptrace_getsiginfo(child, &siginfo);
+ if (!ret)
+ ret = copy_siginfo_to_user32(
+ (struct compat_siginfo __user *) datap,
+ &siginfo);
+ break;
+
+ case PTRACE_SETSIGINFO:
+ memset(&siginfo, 0, sizeof siginfo);
+ if (copy_siginfo_from_user32(
+ &siginfo, (struct compat_siginfo __user *) datap))
+ ret = -EFAULT;
+ else
+ ret = ptrace_setsiginfo(child, &siginfo);
+ break;
+
default:
ret = ptrace_request(child, request, addr, data);
}

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