[PATCH] sysctl: implement sysctl_uts_string()

The problem: When using sys_sysctl we don't read the proper values for the
variables exported from the uts namespace, nor do we do the proper locking.

This patch introduces sysctl_uts_string which properly fetches the values and
does the proper locking.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 32 insertions, 5 deletions

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c8bcbfb2e069..77ea4fc386ef 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -137,6 +137,10 @@ static int parse_table(int __user *, int, void __user *, size_t __user *,
 static int proc_do_uts_string(ctl_table *table, int write, struct file *filp,
                   void __user *buffer, size_t *lenp, loff_t *ppos);
 
+static int sysctl_uts_string(ctl_table *table, int __user *name, int nlen,
+                  void __user *oldval, size_t __user *oldlenp,
+                  void __user *newval, size_t newlen, void **context);
+
 #ifdef CONFIG_PROC_SYSCTL
 static int proc_do_cad_pid(ctl_table *table, int write, struct file *filp,
                   void __user *buffer, size_t *lenp, loff_t *ppos);
@@ -258,7 +262,7 @@ static ctl_table kern_table[] = {
                 .maxlen         = sizeof(init_uts_ns.name.sysname),
                 .mode           = 0444,
                 .proc_handler   = &proc_do_uts_string,
-                .strategy       = &sysctl_string,
+                .strategy       = &sysctl_uts_string,
         },
         {
                 .ctl_name       = KERN_OSRELEASE,
@@ -267,7 +271,7 @@ static ctl_table kern_table[] = {
                 .maxlen         = sizeof(init_uts_ns.name.release),
                 .mode           = 0444,
                 .proc_handler   = &proc_do_uts_string,
-                .strategy       = &sysctl_string,
+                .strategy       = &sysctl_uts_string,
         },
         {
                 .ctl_name       = KERN_VERSION,
@@ -276,7 +280,7 @@ static ctl_table kern_table[] = {
                 .maxlen         = sizeof(init_uts_ns.name.version),
                 .mode           = 0444,
                 .proc_handler   = &proc_do_uts_string,
-                .strategy       = &sysctl_string,
+                .strategy       = &sysctl_uts_string,
         },
         {
                 .ctl_name       = KERN_NODENAME,
@@ -285,7 +289,7 @@ static ctl_table kern_table[] = {
                 .maxlen         = sizeof(init_uts_ns.name.nodename),
                 .mode           = 0644,
                 .proc_handler   = &proc_do_uts_string,
-                .strategy       = &sysctl_string,
+                .strategy       = &sysctl_uts_string,
         },
         {
                 .ctl_name       = KERN_DOMAINNAME,
@@ -294,7 +298,7 @@ static ctl_table kern_table[] = {
                 .maxlen         = sizeof(init_uts_ns.name.domainname),
                 .mode           = 0644,
                 .proc_handler   = &proc_do_uts_string,
-                .strategy       = &sysctl_string,
+                .strategy       = &sysctl_uts_string,
         },
         {
                 .ctl_name       = KERN_PANIC,
@@ -2598,6 +2602,23 @@ int sysctl_ms_jiffies(ctl_table *table, int __user *name, int nlen,
         return 1;
 }
 
+
+/* The generic string strategy routine: */
+static int sysctl_uts_string(ctl_table *table, int __user *name, int nlen,
+                  void __user *oldval, size_t __user *oldlenp,
+                  void __user *newval, size_t newlen, void **context)
+{
+        struct ctl_table uts_table;
+        int r, write;
+        write = newval && newlen;
+        memcpy(&uts_table, table, sizeof(uts_table));
+        uts_table.data = get_uts(table, write);
+        r = sysctl_string(&uts_table, name, nlen,
+                oldval, oldlenp, newval, newlen, context);
+        put_uts(table, write, uts_table.data);
+        return r;
+}
+
 #else /* CONFIG_SYSCTL_SYSCALL */
 
 
@@ -2662,6 +2683,12 @@ int sysctl_ms_jiffies(ctl_table *table, int __user *name, int nlen,
         return -ENOSYS;
 }
 
+static int sysctl_uts_string(ctl_table *table, int __user *name, int nlen,
+                  void __user *oldval, size_t __user *oldlenp,
+                  void __user *newval, size_t newlen, void **context)
+{
+        return -ENOSYS;
+}
 #endif /* CONFIG_SYSCTL_SYSCALL */
 
 /*