On Thu, Nov 22, 2018 at 04:19:10PM -0800, Andy Lutomirski wrote: > On Thu, Nov 22, 2018 at 11:15 AM Dmitry V. Levin <[email protected]> wrote: > > > > On Thu, Nov 22, 2018 at 06:55:29AM -0800, Andy Lutomirski wrote: > > > On Wed, Nov 21, 2018 at 3:56 PM Dmitry V. Levin wrote: > > > > On Wed, Nov 21, 2018 at 02:56:57PM -0800, Andy Lutomirski wrote: > > > > > Please cc [email protected] for future versions. > > > > > > > > > > On Wed, Nov 21, 2018 at 7:58 AM Elvira Khabirova wrote: > > > > > > > > > > > > struct ptrace_syscall_info { > > > > > > __u8 op; /* 0 for entry, 1 for exit */ > > > > > > > > > > Can you add proper defines, like: > > > > > > > > > > #define PTRACE_SYSCALL_ENTRY 0 > > > > > #define PTRACE_SYSCALL_EXIT 1 > > > > > #define PTRACE_SYSCALL_SECCOMP 2 > > > > > > > > > > and make seccomp work from the start? I'd rather we don't merge an > > > > > implementation that doesn't work for seccomp and then have to rework > > > > > it later. > > > > > > > > What's the difference between PTRACE_EVENT_SECCOMP and > > > > syscall-entry-stop > > > > with regards to PTRACE_GET_SYSCALL_INFO request? At least they have the > > > > same entry_info to return. > > > > > > I'm not sure there's any material difference. > > > > In that case we don't really need PTRACE_SYSCALL_SECCOMP: op field > > describes the structure inside the union to use, not the ptrace stop. > > Unless we think the structures might diverge in the future.
If these structures ever diverge, then a seccomp structure will be added
to the union, and a portable userspace code will likely look this way:
#include <linux/ptrace.h>
...
struct ptrace_syscall_info info;
long rc = ptrace(PTRACE_GET_SYSCALL_INFO, pid, (void *) sizeof(info), &info);
...
switch (info.op) {
case PTRACE_SYSCALL_INFO_ENTRY:
/* handle info.entry */
case PTRACE_SYSCALL_INFO_EXIT:
/* handle info.exit */
#ifdef PTRACE_SYSCALL_INFO_SECCOMP
case PTRACE_SYSCALL_INFO_SECCOMP:
/* handle info.seccomp */
#endif
default:
/* handle unknown info.op */
}
In other words, it would be better if PTRACE_SYSCALL_INFO_* selector
constants were introduced along with corresponding structures in the
union.
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