Commit cf9f151c authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Linus Torvalds

[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: default avatarEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 6b1b60f4
......@@ -163,6 +163,28 @@ extern ctl_table inotify_table[];
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 root_table[] = {
};
static ctl_table kern_table[] = {
#ifndef CONFIG_UTS_NS
{
.ctl_name = KERN_OSTYPE,
.procname = "ostype",
......@@ -275,54 +296,6 @@ static ctl_table kern_table[] = {
.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 @@ int proc_dostring(ctl_table *table, int write, struct file *filp,
* 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);
}
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:
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;
}
#endif /* !CONFIG_UTS_NS */
static int do_proc_dointvec_conv(int *negp, unsigned long *lvalp,
int *valp,
......
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