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move seccomp from /proc to a prctl

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This reduces the memory footprint and it enforces that only the current
task can enable seccomp on itself (this is a requirement for a
strightforward [modulo preempt ;) ] TIF_NOTSC implementation).

Signed-off-by: Andrea Arcangeli <andrea@cpushare.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrea Arcangeli
2007-07-15 23:41:32 -07:00
committed by Linus Torvalds
parent be0ef957c9
commit 1d9d02feee
5 changed files with 51 additions and 74 deletions
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26
kernel/seccomp.c
View File

@ -10,6 +10,7 @@
#include <linux/sched.h>
/* #define SECCOMP_DEBUG 1 */
#define NR_SECCOMP_MODES 1
/*
* Secure computing mode 1 allows only read/write/exit/sigreturn.
@ -54,3 +55,28 @@ void __secure_computing(int this_syscall)
#endif
do_exit(SIGKILL);
}
long prctl_get_seccomp(void)
{
return current->seccomp.mode;
}
long prctl_set_seccomp(unsigned long seccomp_mode)
{
long ret;
/* can set it only once to be even more secure */
ret = -EPERM;
if (unlikely(current->seccomp.mode))
goto out;
ret = -EINVAL;
if (seccomp_mode && seccomp_mode <= NR_SECCOMP_MODES) {
current->seccomp.mode = seccomp_mode;
set_thread_flag(TIF_SECCOMP);
ret = 0;
}
out:
return ret;
}

8
kernel/sys.c
View File

@ -31,6 +31,7 @@
#include <linux/cn_proc.h>
#include <linux/getcpu.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/seccomp.h>
#include <linux/compat.h>
#include <linux/syscalls.h>
@ -2242,6 +2243,13 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
error = SET_ENDIAN(current, arg2);
break;
case PR_GET_SECCOMP:
error = prctl_get_seccomp();
break;
case PR_SET_SECCOMP:
error = prctl_set_seccomp(arg2);
break;
default:
error = -EINVAL;
break;