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Commit da3f6f9b authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

sysctl: Introduce a generic compat sysctl sysctl 



This uses compat_alloc_userspace to remove the various
hacks to allow do_sysctl to write to throuh oldlenp.

The rest of our mature compat syscall helper facitilies
are used as well to ensure we have a nice clean maintainable
compat syscall that can be used on all architectures.

The motiviation for a generic compat sysctl (besides the
obvious hack removal) is to reduce the number of compat
sysctl defintions out there so I can refactor the
binary sysctl implementation.

ppc already used the name compat_sys_sysctl so I remove the
ppcs version here.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
parent 2830b683

arch/powerpc/kernel/sys_ppc32.c

+0 −52
Original line number Diff line number Diff line
@@ -520,58 +520,6 @@ asmlinkage long compat_sys_umask(u32 mask) 
	return sys_umask((int)mask);

}



#ifdef CONFIG_SYSCTL_SYSCALL

struct __sysctl_args32 {

	u32 name;

	int nlen;

	u32 oldval;

	u32 oldlenp;

	u32 newval;

	u32 newlen;

	u32 __unused[4];

};



asmlinkage long compat_sys_sysctl(struct __sysctl_args32 __user *args)

{

	struct __sysctl_args32 tmp;

	int error;

	size_t oldlen;

	size_t __user *oldlenp = NULL;

	unsigned long addr = (((unsigned long)&args->__unused[0]) + 7) & ~7;



	if (copy_from_user(&tmp, args, sizeof(tmp)))

		return -EFAULT;



	if (tmp.oldval && tmp.oldlenp) {

		/* Duh, this is ugly and might not work if sysctl_args

		   is in read-only memory, but do_sysctl does indirectly

		   a lot of uaccess in both directions and we'd have to

		   basically copy the whole sysctl.c here, and

		   glibc's __sysctl uses rw memory for the structure

		   anyway.  */

		oldlenp = (size_t __user *)addr;

		if (get_user(oldlen, (compat_size_t __user *)compat_ptr(tmp.oldlenp)) ||

		    put_user(oldlen, oldlenp))

			return -EFAULT;

	}



	lock_kernel();

	error = do_sysctl(compat_ptr(tmp.name), tmp.nlen,

			  compat_ptr(tmp.oldval), oldlenp,

			  compat_ptr(tmp.newval), tmp.newlen);

	unlock_kernel();

	if (oldlenp) {

		if (!error) {

			if (get_user(oldlen, oldlenp) ||

			    put_user(oldlen, (compat_size_t __user *)compat_ptr(tmp.oldlenp)))

				error = -EFAULT;

		}

		copy_to_user(args->__unused, tmp.__unused, sizeof(tmp.__unused));

	}

	return error;

}

#endif



unsigned long compat_sys_mmap2(unsigned long addr, size_t len,

			  unsigned long prot, unsigned long flags,

			  unsigned long fd, unsigned long pgoff)

kernel/sysctl_binary.c

+50 −0
Original line number Diff line number Diff line
@@ -176,3 +176,53 @@ SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args) 


	return error;

}



#ifdef CONFIG_COMPAT

#include <asm/compat.h>



struct compat_sysctl_args {

	compat_uptr_t	name;

	int		nlen;

	compat_uptr_t	oldval;

	compat_uptr_t	oldlenp;

	compat_uptr_t	newval;

	compat_size_t	newlen;

	compat_ulong_t	__unused[4];

};



asmlinkage long compat_sys_sysctl(struct compat_sysctl_args __user *args)

{

	struct compat_sysctl_args tmp;

	compat_size_t __user *compat_oldlenp;

	size_t __user *oldlenp = NULL;

	size_t oldlen = 0;

	ssize_t result;



	if (copy_from_user(&tmp, args, sizeof(tmp)))

		return -EFAULT;



	compat_oldlenp = compat_ptr(tmp.oldlenp);

	if (compat_oldlenp) {

		oldlenp = compat_alloc_user_space(sizeof(*compat_oldlenp));



		if (get_user(oldlen, compat_oldlenp) ||

		    put_user(oldlen, oldlenp))

			return -EFAULT;

	}



	lock_kernel();

	result = do_sysctl(compat_ptr(tmp.name), tmp.nlen,

			   compat_ptr(tmp.oldval), oldlenp,

			   compat_ptr(tmp.newval), tmp.newlen);

	unlock_kernel();



	if (oldlenp && !result) {

		if (get_user(oldlen, oldlenp) ||

		    put_user(oldlen, compat_oldlenp))

			return -EFAULT;

	}



	return result;

}



#endif /* CONFIG_COMPAT */