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* [PATCH] ptrace, seccomp: add support for retrieving seccomp flags
@ 2017-09-19 17:47 Tycho Andersen
  2017-09-19 20:08 ` Kees Cook
  0 siblings, 1 reply; 6+ messages in thread
From: Tycho Andersen @ 2017-09-19 17:47 UTC (permalink / raw)
  To: Kees Cook
  Cc: linux-kernel, criu, Tycho Andersen, Andy Lutomirski,
	Oleg Nesterov

With the new SECCOMP_FILTER_FLAG_LOG, we need to be able to extract these
flags for checkpoint restore, since they describe the state of a filter.

So, let's add PTRACE_SECCOMP_GET_FLAGS, similar to ..._GET_FILTER, which
returns the flags of the nth filter.

Signed-off-by: Tycho Andersen <tycho@docker.com>
CC: Kees Cook <keescook@chromium.org>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Oleg Nesterov <oleg@redhat.com>
---
 include/linux/seccomp.h     |  7 +++++
 include/uapi/linux/ptrace.h |  1 +
 kernel/ptrace.c             |  4 +++
 kernel/seccomp.c            | 74 ++++++++++++++++++++++++++++++++++-----------
 4 files changed, 68 insertions(+), 18 deletions(-)

diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index c8bef436b61d..4713d62378e3 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -94,11 +94,18 @@ static inline void get_seccomp_filter(struct task_struct *tsk)
 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
 extern long seccomp_get_filter(struct task_struct *task,
 			       unsigned long filter_off, void __user *data);
+extern long seccomp_get_flags(struct task_struct *task,
+			      unsigned long filter_off);
 #else
 static inline long seccomp_get_filter(struct task_struct *task,
 				      unsigned long n, void __user *data)
 {
 	return -EINVAL;
 }
+static inline long seccomp_get_flags(struct task_struct *task,
+				     unsigned long filter_off)
+{
+	return -EINVAL;
+}
 #endif /* CONFIG_SECCOMP_FILTER && CONFIG_CHECKPOINT_RESTORE */
 #endif /* _LINUX_SECCOMP_H */
diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
index fb8106509000..52903f0f6600 100644
--- a/include/uapi/linux/ptrace.h
+++ b/include/uapi/linux/ptrace.h
@@ -65,6 +65,7 @@ struct ptrace_peeksiginfo_args {
 #define PTRACE_SETSIGMASK	0x420b
 
 #define PTRACE_SECCOMP_GET_FILTER	0x420c
+#define PTRACE_SECCOMP_GET_FLAGS	0x420d
 
 /* Read signals from a shared (process wide) queue */
 #define PTRACE_PEEKSIGINFO_SHARED	(1 << 0)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 60f356d91060..fa3d2b4d3bf0 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -1094,6 +1094,10 @@ int ptrace_request(struct task_struct *child, long request,
 		ret = seccomp_get_filter(child, addr, datavp);
 		break;
 
+	case PTRACE_SECCOMP_GET_FLAGS:
+		ret = seccomp_get_flags(child, addr);
+		break;
+
 	default:
 		break;
 	}
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index c24579dfa7a1..67768aaa7952 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -968,24 +968,16 @@ long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
 }
 
 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
-long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
-			void __user *data)
+static struct seccomp_filter *get_nth_filter(struct task_struct *task,
+					     unsigned long filter_off)
 {
 	struct seccomp_filter *filter;
-	struct sock_fprog_kern *fprog;
-	long ret;
 	unsigned long count = 0;
 
-	if (!capable(CAP_SYS_ADMIN) ||
-	    current->seccomp.mode != SECCOMP_MODE_DISABLED) {
-		return -EACCES;
-	}
+	WARN_ON_ONCE(!spin_is_locked(&task->sighand->siglock));
 
-	spin_lock_irq(&task->sighand->siglock);
-	if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
-		ret = -EINVAL;
-		goto out;
-	}
+	if (task->seccomp.mode != SECCOMP_MODE_FILTER)
+		return ERR_PTR(-EINVAL);
 
 	filter = task->seccomp.filter;
 	while (filter) {
@@ -993,10 +985,9 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
 		count++;
 	}
 
-	if (filter_off >= count) {
-		ret = -ENOENT;
-		goto out;
-	}
+	if (filter_off >= count)
+		return ERR_PTR(-ENOENT);
+
 	count -= filter_off;
 
 	filter = task->seccomp.filter;
@@ -1007,7 +998,28 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
 
 	if (WARN_ON(count != 1 || !filter)) {
 		/* The filter tree shouldn't shrink while we're using it. */
-		ret = -ENOENT;
+		return ERR_PTR(-ENOENT);
+	}
+
+	return filter;
+}
+
+long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
+			void __user *data)
+{
+	struct seccomp_filter *filter;
+	struct sock_fprog_kern *fprog;
+	long ret;
+
+	if (!capable(CAP_SYS_ADMIN) ||
+	    current->seccomp.mode != SECCOMP_MODE_DISABLED) {
+		return -EACCES;
+	}
+
+	spin_lock_irq(&task->sighand->siglock);
+	filter = get_nth_filter(task, filter_off);
+	if (IS_ERR(filter)) {
+		ret = PTR_ERR(filter);
 		goto out;
 	}
 
@@ -1038,6 +1050,32 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
 	spin_unlock_irq(&task->sighand->siglock);
 	return ret;
 }
+
+long seccomp_get_flags(struct task_struct *task, unsigned long filter_off)
+{
+	long flags = 0L;
+	struct seccomp_filter *filter;
+
+	if (!capable(CAP_SYS_ADMIN) ||
+	    current->seccomp.mode != SECCOMP_MODE_DISABLED) {
+		return -EACCES;
+	}
+
+	spin_lock_irq(&task->sighand->siglock);
+	filter = get_nth_filter(task, filter_off);
+	if (IS_ERR(filter)) {
+		flags = PTR_ERR(filter);
+		goto out;
+	}
+
+	if (filter->log)
+		flags |= SECCOMP_FILTER_FLAG_LOG;
+
+out:
+	spin_unlock_irq(&task->sighand->siglock);
+	return flags;
+
+}
 #endif
 
 #ifdef CONFIG_SYSCTL
-- 
2.11.0

^ permalink raw reply related	[flat|nested] 6+ messages in thread

* Re: [PATCH] ptrace, seccomp: add support for retrieving seccomp flags
  2017-09-19 17:47 [PATCH] ptrace, seccomp: add support for retrieving seccomp flags Tycho Andersen
@ 2017-09-19 20:08 ` Kees Cook
  2017-09-19 21:09   ` Tycho Andersen
  0 siblings, 1 reply; 6+ messages in thread
From: Kees Cook @ 2017-09-19 20:08 UTC (permalink / raw)
  To: Tycho Andersen; +Cc: LKML, criu, Andy Lutomirski, Oleg Nesterov

On Tue, Sep 19, 2017 at 10:47 AM, Tycho Andersen <tycho@docker.com> wrote:
> With the new SECCOMP_FILTER_FLAG_LOG, we need to be able to extract these
> flags for checkpoint restore, since they describe the state of a filter.
>
> So, let's add PTRACE_SECCOMP_GET_FLAGS, similar to ..._GET_FILTER, which
> returns the flags of the nth filter.

Can you split this up into factoring out the nth helper, and then
adding the new get?

For naming, perhaps "GET_FILTER_FLAGS" instead of "GET_FLAGS" since
there may be seccomp flags in the future, etc.

Is there any sane way to add the flags to the existing GET_FILTER?

-Kees

>
> Signed-off-by: Tycho Andersen <tycho@docker.com>
> CC: Kees Cook <keescook@chromium.org>
> CC: Andy Lutomirski <luto@amacapital.net>
> CC: Oleg Nesterov <oleg@redhat.com>
> ---
>  include/linux/seccomp.h     |  7 +++++
>  include/uapi/linux/ptrace.h |  1 +
>  kernel/ptrace.c             |  4 +++
>  kernel/seccomp.c            | 74 ++++++++++++++++++++++++++++++++++-----------
>  4 files changed, 68 insertions(+), 18 deletions(-)
>
> diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
> index c8bef436b61d..4713d62378e3 100644
> --- a/include/linux/seccomp.h
> +++ b/include/linux/seccomp.h
> @@ -94,11 +94,18 @@ static inline void get_seccomp_filter(struct task_struct *tsk)
>  #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
>  extern long seccomp_get_filter(struct task_struct *task,
>                                unsigned long filter_off, void __user *data);
> +extern long seccomp_get_flags(struct task_struct *task,
> +                             unsigned long filter_off);
>  #else
>  static inline long seccomp_get_filter(struct task_struct *task,
>                                       unsigned long n, void __user *data)
>  {
>         return -EINVAL;
>  }
> +static inline long seccomp_get_flags(struct task_struct *task,
> +                                    unsigned long filter_off)
> +{
> +       return -EINVAL;
> +}
>  #endif /* CONFIG_SECCOMP_FILTER && CONFIG_CHECKPOINT_RESTORE */
>  #endif /* _LINUX_SECCOMP_H */
> diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
> index fb8106509000..52903f0f6600 100644
> --- a/include/uapi/linux/ptrace.h
> +++ b/include/uapi/linux/ptrace.h
> @@ -65,6 +65,7 @@ struct ptrace_peeksiginfo_args {
>  #define PTRACE_SETSIGMASK      0x420b
>
>  #define PTRACE_SECCOMP_GET_FILTER      0x420c
> +#define PTRACE_SECCOMP_GET_FLAGS       0x420d
>
>  /* Read signals from a shared (process wide) queue */
>  #define PTRACE_PEEKSIGINFO_SHARED      (1 << 0)
> diff --git a/kernel/ptrace.c b/kernel/ptrace.c
> index 60f356d91060..fa3d2b4d3bf0 100644
> --- a/kernel/ptrace.c
> +++ b/kernel/ptrace.c
> @@ -1094,6 +1094,10 @@ int ptrace_request(struct task_struct *child, long request,
>                 ret = seccomp_get_filter(child, addr, datavp);
>                 break;
>
> +       case PTRACE_SECCOMP_GET_FLAGS:
> +               ret = seccomp_get_flags(child, addr);
> +               break;
> +
>         default:
>                 break;
>         }
> diff --git a/kernel/seccomp.c b/kernel/seccomp.c
> index c24579dfa7a1..67768aaa7952 100644
> --- a/kernel/seccomp.c
> +++ b/kernel/seccomp.c
> @@ -968,24 +968,16 @@ long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
>  }
>
>  #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
> -long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
> -                       void __user *data)
> +static struct seccomp_filter *get_nth_filter(struct task_struct *task,
> +                                            unsigned long filter_off)
>  {
>         struct seccomp_filter *filter;
> -       struct sock_fprog_kern *fprog;
> -       long ret;
>         unsigned long count = 0;
>
> -       if (!capable(CAP_SYS_ADMIN) ||
> -           current->seccomp.mode != SECCOMP_MODE_DISABLED) {
> -               return -EACCES;
> -       }
> +       WARN_ON_ONCE(!spin_is_locked(&task->sighand->siglock));
>
> -       spin_lock_irq(&task->sighand->siglock);
> -       if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
> -               ret = -EINVAL;
> -               goto out;
> -       }
> +       if (task->seccomp.mode != SECCOMP_MODE_FILTER)
> +               return ERR_PTR(-EINVAL);
>
>         filter = task->seccomp.filter;
>         while (filter) {
> @@ -993,10 +985,9 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
>                 count++;
>         }
>
> -       if (filter_off >= count) {
> -               ret = -ENOENT;
> -               goto out;
> -       }
> +       if (filter_off >= count)
> +               return ERR_PTR(-ENOENT);
> +
>         count -= filter_off;
>
>         filter = task->seccomp.filter;
> @@ -1007,7 +998,28 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
>
>         if (WARN_ON(count != 1 || !filter)) {
>                 /* The filter tree shouldn't shrink while we're using it. */
> -               ret = -ENOENT;
> +               return ERR_PTR(-ENOENT);
> +       }
> +
> +       return filter;
> +}
> +
> +long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
> +                       void __user *data)
> +{
> +       struct seccomp_filter *filter;
> +       struct sock_fprog_kern *fprog;
> +       long ret;
> +
> +       if (!capable(CAP_SYS_ADMIN) ||
> +           current->seccomp.mode != SECCOMP_MODE_DISABLED) {
> +               return -EACCES;
> +       }
> +
> +       spin_lock_irq(&task->sighand->siglock);
> +       filter = get_nth_filter(task, filter_off);
> +       if (IS_ERR(filter)) {
> +               ret = PTR_ERR(filter);
>                 goto out;
>         }
>
> @@ -1038,6 +1050,32 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
>         spin_unlock_irq(&task->sighand->siglock);
>         return ret;
>  }
> +
> +long seccomp_get_flags(struct task_struct *task, unsigned long filter_off)
> +{
> +       long flags = 0L;
> +       struct seccomp_filter *filter;
> +
> +       if (!capable(CAP_SYS_ADMIN) ||
> +           current->seccomp.mode != SECCOMP_MODE_DISABLED) {
> +               return -EACCES;
> +       }
> +
> +       spin_lock_irq(&task->sighand->siglock);
> +       filter = get_nth_filter(task, filter_off);
> +       if (IS_ERR(filter)) {
> +               flags = PTR_ERR(filter);
> +               goto out;
> +       }
> +
> +       if (filter->log)
> +               flags |= SECCOMP_FILTER_FLAG_LOG;
> +
> +out:
> +       spin_unlock_irq(&task->sighand->siglock);
> +       return flags;
> +
> +}
>  #endif
>
>  #ifdef CONFIG_SYSCTL
> --
> 2.11.0
>



-- 
Kees Cook
Pixel Security

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] ptrace, seccomp: add support for retrieving seccomp flags
  2017-09-19 20:08 ` Kees Cook
@ 2017-09-19 21:09   ` Tycho Andersen
  2017-09-19 21:43     ` Kees Cook
  0 siblings, 1 reply; 6+ messages in thread
From: Tycho Andersen @ 2017-09-19 21:09 UTC (permalink / raw)
  To: Kees Cook; +Cc: LKML, criu, Andy Lutomirski, Oleg Nesterov

Hi Kees,

On Tue, Sep 19, 2017 at 01:08:28PM -0700, Kees Cook wrote:
> On Tue, Sep 19, 2017 at 10:47 AM, Tycho Andersen <tycho@docker.com> wrote:
> > With the new SECCOMP_FILTER_FLAG_LOG, we need to be able to extract these
> > flags for checkpoint restore, since they describe the state of a filter.
> >
> > So, let's add PTRACE_SECCOMP_GET_FLAGS, similar to ..._GET_FILTER, which
> > returns the flags of the nth filter.
> 
> Can you split this up into factoring out the nth helper, and then
> adding the new get?
> 
> For naming, perhaps "GET_FILTER_FLAGS" instead of "GET_FLAGS" since
> there may be seccomp flags in the future, etc.

Sure, I'll do both of these.

> Is there any sane way to add the flags to the existing GET_FILTER?

I looked at this, and I don't think so. Unfortunately, we didn't use
any structure for the output, it's just the raw bytes of the filter
with the length used as the return value. I suppose we could append
the flags after the bytes of the filter, but that seems... very ugly
:). Let me know if you want to go that route.

Tycho

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] ptrace, seccomp: add support for retrieving seccomp flags
  2017-09-19 21:09   ` Tycho Andersen
@ 2017-09-19 21:43     ` Kees Cook
  2017-09-19 21:55       ` Tycho Andersen
  0 siblings, 1 reply; 6+ messages in thread
From: Kees Cook @ 2017-09-19 21:43 UTC (permalink / raw)
  To: Tycho Andersen; +Cc: LKML, criu, Andy Lutomirski, Oleg Nesterov

On Tue, Sep 19, 2017 at 2:09 PM, Tycho Andersen <tycho@docker.com> wrote:
> Hi Kees,
>
> On Tue, Sep 19, 2017 at 01:08:28PM -0700, Kees Cook wrote:
>> On Tue, Sep 19, 2017 at 10:47 AM, Tycho Andersen <tycho@docker.com> wrote:
>> > With the new SECCOMP_FILTER_FLAG_LOG, we need to be able to extract these
>> > flags for checkpoint restore, since they describe the state of a filter.
>> >
>> > So, let's add PTRACE_SECCOMP_GET_FLAGS, similar to ..._GET_FILTER, which
>> > returns the flags of the nth filter.
>>
>> Can you split this up into factoring out the nth helper, and then
>> adding the new get?
>>
>> For naming, perhaps "GET_FILTER_FLAGS" instead of "GET_FLAGS" since
>> there may be seccomp flags in the future, etc.
>
> Sure, I'll do both of these.
>
>> Is there any sane way to add the flags to the existing GET_FILTER?
>
> I looked at this, and I don't think so. Unfortunately, we didn't use
> any structure for the output, it's just the raw bytes of the filter
> with the length used as the return value. I suppose we could append
> the flags after the bytes of the filter, but that seems... very ugly
> :). Let me know if you want to go that route.

I think if we can make the new GET_FILTER_stuff interface more
extensible, we should cover any future needs for per-filter content.
BUt yeah, I agree, when I looked at this when I first mailed you about
it, I agree: it looked more ugly to extend the existing GET_FILTER.

-Kees

-- 
Kees Cook
Pixel Security

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] ptrace, seccomp: add support for retrieving seccomp flags
  2017-09-19 21:43     ` Kees Cook
@ 2017-09-19 21:55       ` Tycho Andersen
  2017-09-19 22:09         ` Kees Cook
  0 siblings, 1 reply; 6+ messages in thread
From: Tycho Andersen @ 2017-09-19 21:55 UTC (permalink / raw)
  To: Kees Cook; +Cc: LKML, criu, Andy Lutomirski, Oleg Nesterov

On Tue, Sep 19, 2017 at 02:43:51PM -0700, Kees Cook wrote:
> On Tue, Sep 19, 2017 at 2:09 PM, Tycho Andersen <tycho@docker.com> wrote:
> > Hi Kees,
> >
> > On Tue, Sep 19, 2017 at 01:08:28PM -0700, Kees Cook wrote:
> >> On Tue, Sep 19, 2017 at 10:47 AM, Tycho Andersen <tycho@docker.com> wrote:
> >> > With the new SECCOMP_FILTER_FLAG_LOG, we need to be able to extract these
> >> > flags for checkpoint restore, since they describe the state of a filter.
> >> >
> >> > So, let's add PTRACE_SECCOMP_GET_FLAGS, similar to ..._GET_FILTER, which
> >> > returns the flags of the nth filter.
> >>
> >> Can you split this up into factoring out the nth helper, and then
> >> adding the new get?
> >>
> >> For naming, perhaps "GET_FILTER_FLAGS" instead of "GET_FLAGS" since
> >> there may be seccomp flags in the future, etc.
> >
> > Sure, I'll do both of these.
> >
> >> Is there any sane way to add the flags to the existing GET_FILTER?
> >
> > I looked at this, and I don't think so. Unfortunately, we didn't use
> > any structure for the output, it's just the raw bytes of the filter
> > with the length used as the return value. I suppose we could append
> > the flags after the bytes of the filter, but that seems... very ugly
> > :). Let me know if you want to go that route.
> 
> I think if we can make the new GET_FILTER_stuff interface more
> extensible, we should cover any future needs for per-filter content.

Ok, are you interested in something more general than
GET_FILTER_FLAGS? Maybe GET_FILTER_METADATA with uapi struct like:

struct seccomp_metadata {
    unsigned int flags;
};

which you call by something like,

struct seccomp_metadata mymeta;

size = ptrace(PTRACE_SECCOMP_GET_FILTER_METADATA, pid, sizeof(mymeta), &mymeta);
if (size < 0) {
    /* error */
}
if (size != sizeof(mymeta)) {
   /* struct seccomp_metadata sizes are different */
}

?

Tycho

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] ptrace, seccomp: add support for retrieving seccomp flags
  2017-09-19 21:55       ` Tycho Andersen
@ 2017-09-19 22:09         ` Kees Cook
  0 siblings, 0 replies; 6+ messages in thread
From: Kees Cook @ 2017-09-19 22:09 UTC (permalink / raw)
  To: Tycho Andersen, Linux API; +Cc: LKML, criu, Andy Lutomirski, Oleg Nesterov

On Tue, Sep 19, 2017 at 2:55 PM, Tycho Andersen <tycho@docker.com> wrote:
> On Tue, Sep 19, 2017 at 02:43:51PM -0700, Kees Cook wrote:
>> On Tue, Sep 19, 2017 at 2:09 PM, Tycho Andersen <tycho@docker.com> wrote:
>> > Hi Kees,
>> >
>> > On Tue, Sep 19, 2017 at 01:08:28PM -0700, Kees Cook wrote:
>> >> On Tue, Sep 19, 2017 at 10:47 AM, Tycho Andersen <tycho@docker.com> wrote:
>> >> > With the new SECCOMP_FILTER_FLAG_LOG, we need to be able to extract these
>> >> > flags for checkpoint restore, since they describe the state of a filter.
>> >> >
>> >> > So, let's add PTRACE_SECCOMP_GET_FLAGS, similar to ..._GET_FILTER, which
>> >> > returns the flags of the nth filter.
>> >>
>> >> Can you split this up into factoring out the nth helper, and then
>> >> adding the new get?
>> >>
>> >> For naming, perhaps "GET_FILTER_FLAGS" instead of "GET_FLAGS" since
>> >> there may be seccomp flags in the future, etc.
>> >
>> > Sure, I'll do both of these.
>> >
>> >> Is there any sane way to add the flags to the existing GET_FILTER?
>> >
>> > I looked at this, and I don't think so. Unfortunately, we didn't use
>> > any structure for the output, it's just the raw bytes of the filter
>> > with the length used as the return value. I suppose we could append
>> > the flags after the bytes of the filter, but that seems... very ugly
>> > :). Let me know if you want to go that route.
>>
>> I think if we can make the new GET_FILTER_stuff interface more
>> extensible, we should cover any future needs for per-filter content.
>
> Ok, are you interested in something more general than
> GET_FILTER_FLAGS? Maybe GET_FILTER_METADATA with uapi struct like:
>
> struct seccomp_metadata {
>     unsigned int flags;
> };
>
> which you call by something like,
>
> struct seccomp_metadata mymeta;
>
> size = ptrace(PTRACE_SECCOMP_GET_FILTER_METADATA, pid, sizeof(mymeta), &mymeta);
> if (size < 0) {
>     /* error */
> }
> if (size != sizeof(mymeta)) {
>    /* struct seccomp_metadata sizes are different */
> }
>
> ?

Yeah, I think a sizeof could work here as a way to grow the metadata
result in the future.

Adding linux-api@ to see if anyone has thoughts on the best way to
make this future-proof...

-Kees

-- 
Kees Cook
Pixel Security

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2017-09-19 22:09 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2017-09-19 17:47 [PATCH] ptrace, seccomp: add support for retrieving seccomp flags Tycho Andersen
2017-09-19 20:08 ` Kees Cook
2017-09-19 21:09   ` Tycho Andersen
2017-09-19 21:43     ` Kees Cook
2017-09-19 21:55       ` Tycho Andersen
2017-09-19 22:09         ` Kees Cook

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