[PATCH] sysctl: simplify sysctl_uts_string
The binary interface to the namespace sysctls was never implemented resulting
in some really weird things if you attempted to use sys_sysctl to read your
hostname for example.
This patch series simples the code a little and implements the binary sysctl
interface.
In testing this patch series I discovered that our 32bit compatibility for the
binary sysctl interface is imperfect. In particular KERN_SHMMAX and
KERN_SMMALL are size_t sized quantities and are returned as 8 bytes on to
32bit binaries using a x86_64 kernel. However this has existing for a long
time so it is not a new regression with the namespace work.
Gads the whole sysctl thing needs work before it stops being easy to shoot
yourself in the foot.
Looking forward a little bit we need a better way to handle sysctls and
namespaces as our current technique will not work for the network namespace.
I think something based on the current overlapping sysctl trees will work but
the proc side needs to be redone before we can use it.
This patch:
Introduce get_uts() and put_uts() (used later) and remove most of the special
cases for when UTS namespace is compiled in.
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>
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 9846db9..c8bcbfb 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -163,6 +163,28 @@
int sysctl_legacy_va_layout;
#endif
+static void *get_uts(ctl_table *table, int write)
+{
+ char *which = table->data;
+#ifdef CONFIG_UTS_NS
+ struct uts_namespace *uts_ns = current->nsproxy->uts_ns;
+ which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
+#endif
+ if (!write)
+ down_read(&uts_sem);
+ else
+ down_write(&uts_sem);
+ return which;
+}
+
+static void put_uts(ctl_table *table, int write, void *which)
+{
+ if (!write)
+ up_read(&uts_sem);
+ else
+ up_write(&uts_sem);
+}
+
/* /proc declarations: */
#ifdef CONFIG_PROC_SYSCTL
@@ -229,7 +251,6 @@
};
static ctl_table kern_table[] = {
-#ifndef CONFIG_UTS_NS
{
.ctl_name = KERN_OSTYPE,
.procname = "ostype",
@@ -275,54 +296,6 @@
.proc_handler = &proc_do_uts_string,
.strategy = &sysctl_string,
},
-#else /* !CONFIG_UTS_NS */
- {
- .ctl_name = KERN_OSTYPE,
- .procname = "ostype",
- .data = NULL,
- /* could maybe use __NEW_UTS_LEN here? */
- .maxlen = FIELD_SIZEOF(struct new_utsname, sysname),
- .mode = 0444,
- .proc_handler = &proc_do_uts_string,
- .strategy = &sysctl_string,
- },
- {
- .ctl_name = KERN_OSRELEASE,
- .procname = "osrelease",
- .data = NULL,
- .maxlen = FIELD_SIZEOF(struct new_utsname, release),
- .mode = 0444,
- .proc_handler = &proc_do_uts_string,
- .strategy = &sysctl_string,
- },
- {
- .ctl_name = KERN_VERSION,
- .procname = "version",
- .data = NULL,
- .maxlen = FIELD_SIZEOF(struct new_utsname, version),
- .mode = 0444,
- .proc_handler = &proc_do_uts_string,
- .strategy = &sysctl_string,
- },
- {
- .ctl_name = KERN_NODENAME,
- .procname = "hostname",
- .data = NULL,
- .maxlen = FIELD_SIZEOF(struct new_utsname, nodename),
- .mode = 0644,
- .proc_handler = &proc_do_uts_string,
- .strategy = &sysctl_string,
- },
- {
- .ctl_name = KERN_DOMAINNAME,
- .procname = "domainname",
- .data = NULL,
- .maxlen = FIELD_SIZEOF(struct new_utsname, domainname),
- .mode = 0644,
- .proc_handler = &proc_do_uts_string,
- .strategy = &sysctl_string,
- },
-#endif /* !CONFIG_UTS_NS */
{
.ctl_name = KERN_PANIC,
.procname = "panic",
@@ -1753,66 +1726,17 @@
* Special case of dostring for the UTS structure. This has locks
* to observe. Should this be in kernel/sys.c ????
*/
-
-#ifndef CONFIG_UTS_NS
+
static int proc_do_uts_string(ctl_table *table, int write, struct file *filp,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
int r;
-
- if (!write) {
- down_read(&uts_sem);
- r=proc_dostring(table,0,filp,buffer,lenp, ppos);
- up_read(&uts_sem);
- } else {
- down_write(&uts_sem);
- r=proc_dostring(table,1,filp,buffer,lenp, ppos);
- up_write(&uts_sem);
- }
+ void *which;
+ which = get_uts(table, write);
+ r = _proc_do_string(which, table->maxlen,write,filp,buffer,lenp, ppos);
+ put_uts(table, write, which);
return r;
}
-#else /* !CONFIG_UTS_NS */
-static int proc_do_uts_string(ctl_table *table, int write, struct file *filp,
- void __user *buffer, size_t *lenp, loff_t *ppos)
-{
- int r;
- struct uts_namespace* uts_ns = current->nsproxy->uts_ns;
- char* which;
-
- switch (table->ctl_name) {
- case KERN_OSTYPE:
- which = uts_ns->name.sysname;
- break;
- case KERN_NODENAME:
- which = uts_ns->name.nodename;
- break;
- case KERN_OSRELEASE:
- which = uts_ns->name.release;
- break;
- case KERN_VERSION:
- which = uts_ns->name.version;
- break;
- case KERN_DOMAINNAME:
- which = uts_ns->name.domainname;
- break;
- default:
- r = -EINVAL;
- goto out;
- }
-
- if (!write) {
- down_read(&uts_sem);
- r=_proc_do_string(which,table->maxlen,0,filp,buffer,lenp, ppos);
- up_read(&uts_sem);
- } else {
- down_write(&uts_sem);
- r=_proc_do_string(which,table->maxlen,1,filp,buffer,lenp, ppos);
- up_write(&uts_sem);
- }
- out:
- return r;
-}
-#endif /* !CONFIG_UTS_NS */
static int do_proc_dointvec_conv(int *negp, unsigned long *lvalp,
int *valp,