[PATCH 03/11] sysctl: Introduce a generic compat sysctl sysctl

Eric W. Biederman
2009-11-06T00:43:17Z

From: Eric W. Biederman <ebiederm@xmission.com>

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>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
arch/powerpc/kernel/sys_ppc32.c | 52 ---------------------------------------
kernel/sysctl_binary.c | 50 +++++++++++++++++++++++++++++++++++++
2 files changed, 50 insertions(+), 52 deletions(-)

diff --git a/arch/powerpc/kernel/sys_ppc32.c b/arch/powerpc/kernel/sys_ppc32.c
index b97c2d6..c5a4732 100644
--- a/arch/powerpc/kernel/sys_ppc32.c
+++ b/arch/powerpc/kernel/sys_ppc32.c
@@ -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)
diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index c5cc393..a2fed5b 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -175,3 +175,53 @@ 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 */
--
1.6.5.2.143.g8cc62