[PATCH 02/11] sysctl: Refactor the binary sysctl handling to remove duplicate code

Eric W. Biederman
2009-11-06T00:42:14Z

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

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>
---
kernel/sysctl_binary.c | 123 ++++++++++++++++++++++-------------------------
1 files changed, 58 insertions(+), 65 deletions(-)

diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index 2431653..c5cc393 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -13,8 +13,6 @@
#include <linux/file.h>
#include <linux/ctype.h>

-static int deprecated_sysctl_warning(struct __sysctl_args *args);
-
#ifdef CONFIG_SYSCTL_SYSCALL

/* Perform the actual read/write of a sysctl table entry. */
@@ -50,7 +48,7 @@ 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,
@@ -60,8 +58,7 @@ 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;
@@ -84,19 +81,13 @@ 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)) {
@@ -111,74 +102,76 @@ 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;
}
--
1.6.5.2.143.g8cc62