sysctl: Refactor the binary sysctl handling to remove duplicate code

Read in the binary sysctl path once, instead of reread it
from user space each time the code needs to access a path
element.

The deprecated sysctl warning is moved to do_sysctl so
that the compat_sysctl entries syscalls will also warn.

The return of -ENOSYS when !CONFIG_SYSCTL_SYSCALL is moved
to binary_sysctl.  Always leaving a do_sysctl available
that handles !CONFIG_SYSCTL_SYSCALL and printing the
deprecated sysctl warning allows for a single defitition
of the sysctl syscall.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index eceeed2..930a31c 100644 (file)
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -14,8 +14,6 @@
 #include <linux/ctype.h>
 #include <linux/smp_lock.h>
 
-static int deprecated_sysctl_warning(struct __sysctl_args *args);
-
 #ifdef CONFIG_SYSCTL_SYSCALL
 
 /* Perform the actual read/write of a sysctl table entry. */
@@ -51,7 +49,7 @@ static int do_sysctl_strategy(struct ctl_table_root *root,
        return 0;
 }
 
-static int parse_table(int __user *name, int nlen,
+static int parse_table(const int *name, int nlen,
                       void __user *oldval, size_t __user *oldlenp,
                       void __user *newval, size_t newlen,
                       struct ctl_table_root *root,
@@ -61,8 +59,7 @@ static int parse_table(int __user *name, int nlen,
 repeat:
        if (!nlen)
                return -ENOTDIR;
-       if (get_user(n, name))
-               return -EFAULT;
+       n = *name;
        for ( ; table->ctl_name || table->procname; table++) {
                if (!table->ctl_name)
                        continue;
@@ -85,19 +82,13 @@ repeat:
        return -ENOTDIR;
 }
 
-int do_sysctl(int __user *name, int nlen, void __user *oldval, size_t __user *oldlenp,
-              void __user *newval, size_t newlen)
+static ssize_t binary_sysctl(const int *name, int nlen,
+       void __user *oldval, size_t __user *oldlenp,
+       void __user *newval, size_t newlen)
+
 {
        struct ctl_table_header *head;
-       int error = -ENOTDIR;
-
-       if (nlen <= 0 || nlen >= CTL_MAXNAME)
-               return -ENOTDIR;
-       if (oldval) {
-               int old_len;
-               if (!oldlenp || get_user(old_len, oldlenp))
-                       return -EFAULT;
-       }
+       ssize_t error = -ENOTDIR;
 
        for (head = sysctl_head_next(NULL); head;
                        head = sysctl_head_next(head)) {
@@ -112,74 +103,76 @@ int do_sysctl(int __user *name, int nlen, void __user *oldval, size_t __user *ol
        return error;
 }
 
-SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
-{
-       struct __sysctl_args tmp;
-       int error;
-
-       if (copy_from_user(&tmp, args, sizeof(tmp)))
-               return -EFAULT;
-
-       error = deprecated_sysctl_warning(&tmp);
-       if (error)
-               goto out;
-
-       lock_kernel();
-       error = do_sysctl(tmp.name, tmp.nlen, tmp.oldval, tmp.oldlenp,
-                         tmp.newval, tmp.newlen);
-       unlock_kernel();
-out:
-       return error;
-}
-
 #else /* CONFIG_SYSCTL_SYSCALL */
 
-SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
+static ssize_t binary_sysctl(const int *ctl_name, int nlen,
+       void __user *oldval, size_t __user *oldlenp,
+       void __user *newval, size_t newlen)
 {
-       struct __sysctl_args tmp;
-       int error;
-
-       if (copy_from_user(&tmp, args, sizeof(tmp)))
-               return -EFAULT;
-
-       error = deprecated_sysctl_warning(&tmp);
-
-       /* If no error reading the parameters then just -ENOSYS ... */
-       if (!error)
-               error = -ENOSYS;
-
-       return error;
+       return -ENOSYS;
 }
 
 #endif /* CONFIG_SYSCTL_SYSCALL */
 
-static int deprecated_sysctl_warning(struct __sysctl_args *args)
+static void deprecated_sysctl_warning(const int *name, int nlen)
 {
        static int msg_count;
-       int name[CTL_MAXNAME];
        int i;
 
-       /* Check args->nlen. */
-       if (args->nlen < 0 || args->nlen > CTL_MAXNAME)
-               return -ENOTDIR;
-
-       /* Read in the sysctl name for better debug message logging */
-       for (i = 0; i < args->nlen; i++)
-               if (get_user(name[i], args->name + i))
-                       return -EFAULT;
-
        /* Ignore accesses to kernel.version */
-       if ((args->nlen == 2) && (name[0] == CTL_KERN) && (name[1] == KERN_VERSION))
-               return 0;
+       if ((nlen == 2) && (name[0] == CTL_KERN) && (name[1] == KERN_VERSION))
+               return;
 
        if (msg_count < 5) {
                msg_count++;
                printk(KERN_INFO
                        "warning: process `%s' used the deprecated sysctl "
                        "system call with ", current->comm);
-               for (i = 0; i < args->nlen; i++)
+               for (i = 0; i < nlen; i++)
                        printk("%d.", name[i]);
                printk("\n");
        }
-       return 0;
+       return;
+}
+
+int do_sysctl(int __user *args_name, int nlen,
+       void __user *oldval, size_t __user *oldlenp,
+       void __user *newval, size_t newlen)
+{
+       int name[CTL_MAXNAME];
+       size_t oldlen = 0;
+       int i;
+
+       if (nlen <= 0 || nlen >= CTL_MAXNAME)
+               return -ENOTDIR;
+       if (oldval && !oldlenp)
+               return -EFAULT;
+       if (oldlenp && get_user(oldlen, oldlenp))
+               return -EFAULT;
+
+       /* Read in the sysctl name for simplicity */
+       for (i = 0; i < nlen; i++)
+               if (get_user(name[i], args_name + i))
+                       return -EFAULT;
+
+       deprecated_sysctl_warning(name, nlen);
+
+       return binary_sysctl(name, nlen, oldval, oldlenp, newval, newlen);
+}
+
+
+SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
+{
+       struct __sysctl_args tmp;
+       int error;
+
+       if (copy_from_user(&tmp, args, sizeof(tmp)))
+               return -EFAULT;
+
+       lock_kernel();
+       error = do_sysctl(tmp.name, tmp.nlen, tmp.oldval, tmp.oldlenp,
+                         tmp.newval, tmp.newlen);
+       unlock_kernel();
+
+       return error;
 }