[PATCH 1/3] proc: sysctl: rename proc_doutsstring to proc_do_uts_string

[PATCH 1/3] proc: sysctl: rename proc_doutsstring to proc_do_uts_string

[Sam Vilain]

From: Sam Vilain <sam.vilain@catalyst.net.nz>

'proc_doutsstring' is confusing; delimit the word with more underscores.
---

 kernel/sysctl.c |   16 ++++++++--------
 1 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 708cdcd..618a2f8 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -141,7 +141,7 @@ #endif
 
 static int parse_table(int __user *, int, void __user *, size_t __user *, void __user *, size_t,
 		       ctl_table *, void **);
-static int proc_doutsstring(ctl_table *table, int write, struct file *filp,
+static int proc_do_uts_string(ctl_table *table, int write, struct file *filp,
 		  void __user *buffer, size_t *lenp, loff_t *ppos);
 
 static ctl_table root_table[];
@@ -244,7 +244,7 @@ static ctl_table kern_table[] = {
 		.data		= init_uts_ns.name.sysname,
 		.maxlen		= sizeof(init_uts_ns.name.sysname),
 		.mode		= 0444,
-		.proc_handler	= &proc_doutsstring,
+		.proc_handler	= &proc_do_uts_string,
 		.strategy	= &sysctl_string,
 	},
 	{
@@ -253,7 +253,7 @@ static ctl_table kern_table[] = {
 		.data		= init_uts_ns.name.release,
 		.maxlen		= sizeof(init_uts_ns.name.release),
 		.mode		= 0444,
-		.proc_handler	= &proc_doutsstring,
+		.proc_handler	= &proc_do_uts_string,
 		.strategy	= &sysctl_string,
 	},
 	{
@@ -262,7 +262,7 @@ static ctl_table kern_table[] = {
 		.data		= init_uts_ns.name.version,
 		.maxlen		= sizeof(init_uts_ns.name.version),
 		.mode		= 0444,
-		.proc_handler	= &proc_doutsstring,
+		.proc_handler	= &proc_do_uts_string,
 		.strategy	= &sysctl_string,
 	},
 	{
@@ -271,7 +271,7 @@ static ctl_table kern_table[] = {
 		.data		= init_uts_ns.name.nodename,
 		.maxlen		= sizeof(init_uts_ns.name.nodename),
 		.mode		= 0644,
-		.proc_handler	= &proc_doutsstring,
+		.proc_handler	= &proc_do_uts_string,
 		.strategy	= &sysctl_string,
 	},
 	{
@@ -280,7 +280,7 @@ static ctl_table kern_table[] = {
 		.data		= init_uts_ns.name.domainname,
 		.maxlen		= sizeof(init_uts_ns.name.domainname),
 		.mode		= 0644,
-		.proc_handler	= &proc_doutsstring,
+		.proc_handler	= &proc_do_uts_string,
 		.strategy	= &sysctl_string,
 	},
 	{
@@ -1677,7 +1677,7 @@ int proc_dostring(ctl_table *table, int 
  *	to observe. Should this be in kernel/sys.c ????
  */
  
-static int proc_doutsstring(ctl_table *table, int write, struct file *filp,
+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;
@@ -2256,7 +2256,7 @@ int proc_dostring(ctl_table *table, int 
 	return -ENOSYS;
 }
 
-static int proc_doutsstring(ctl_table *table, int write, struct file *filp,
+static int proc_do_uts_string(ctl_table *table, int write, struct file *filp,
 			    void __user *buffer, size_t *lenp, loff_t *ppos)
 {
 	return -ENOSYS;

>From sam.vilain@catalyst.net.nz Tue May 23 13:23:01 2006
From: Sam Vilain <sam.vilain@catalyst.net.nz>
Subject: [PATCH 2/3] proc: sysctl: add _proc_do_string helper
Date: Tue, 23 May 2006 13:23:01 +1200
To: ebiederm@xmission.com (Eric W. Biederman)
Cc: linux-kernel@vger.kernel.org, "Serge E. Hallyn" <serue@us.ibm.com>, herbert@13thfloor.at, dev@sw.ru, devel@openvz.org, sam@vilain.net, xemul@sw.ru, Dave Hansen <haveblue@us.ibm.com>, Andrew Morton <akpm@osdl.org>, Cedric Le Goater <clg@fr.ibm.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>
Message-Id: <20060523012301.13531.31499.stgit@localhost.localdomain>
In-Reply-To: <20060523012300.13531.96685.stgit@localhost.localdomain>
References: <20060523012300.13531.96685.stgit@localhost.localdomain>

From: Sam Vilain <sam.vilain@catalyst.net.nz>

The logic in proc_do_string is worth re-using without passing in a
ctl_table structure (say, we want to calculate a pointer and pass that
in instead); pass in the two fields it uses from that structure
as explicit arguments.
---

 kernel/sysctl.c |   65 ++++++++++++++++++++++++++++++-------------------------
 1 files changed, 36 insertions(+), 29 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 618a2f8..cf053fc 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1605,32 +1605,14 @@ static ssize_t proc_writesys(struct file
 	return do_rw_proc(1, file, (char __user *) buf, count, ppos);
 }
 
-/**
- * proc_dostring - read a string sysctl
- * @table: the sysctl table
- * @write: %TRUE if this is a write to the sysctl file
- * @filp: the file structure
- * @buffer: the user buffer
- * @lenp: the size of the user buffer
- * @ppos: file position
- *
- * Reads/writes a string from/to the user buffer. If the kernel
- * buffer provided is not large enough to hold the string, the
- * string is truncated. The copied string is %NULL-terminated.
- * If the string is being read by the user process, it is copied
- * and a newline '\n' is added. It is truncated if the buffer is
- * not large enough.
- *
- * Returns 0 on success.
- */
-int proc_dostring(ctl_table *table, int write, struct file *filp,
-		  void __user *buffer, size_t *lenp, loff_t *ppos)
+int _proc_do_string(void* data, int maxlen, int write, struct file *filp,
+		    void __user *buffer, size_t *lenp, loff_t *ppos)
 {
 	size_t len;
 	char __user *p;
 	char c;
 	
-	if (!table->data || !table->maxlen || !*lenp ||
+	if (!data || !maxlen || !*lenp ||
 	    (*ppos && !write)) {
 		*lenp = 0;
 		return 0;
@@ -1646,20 +1628,20 @@ int proc_dostring(ctl_table *table, int 
 				break;
 			len++;
 		}
-		if (len >= table->maxlen)
-			len = table->maxlen-1;
-		if(copy_from_user(table->data, buffer, len))
+		if (len >= maxlen)
+			len = maxlen-1;
+		if(copy_from_user(data, buffer, len))
 			return -EFAULT;
-		((char *) table->data)[len] = 0;
+		((char *) data)[len] = 0;
 		*ppos += *lenp;
 	} else {
-		len = strlen(table->data);
-		if (len > table->maxlen)
-			len = table->maxlen;
+		len = strlen(data);
+		if (len > maxlen)
+			len = maxlen;
 		if (len > *lenp)
 			len = *lenp;
 		if (len)
-			if(copy_to_user(buffer, table->data, len))
+			if(copy_to_user(buffer, data, len))
 				return -EFAULT;
 		if (len < *lenp) {
 			if(put_user('\n', ((char __user *) buffer) + len))
@@ -1672,6 +1654,31 @@ int proc_dostring(ctl_table *table, int 
 	return 0;
 }
 
+/**
+ * proc_dostring - read a string sysctl
+ * @table: the sysctl table
+ * @write: %TRUE if this is a write to the sysctl file
+ * @filp: the file structure
+ * @buffer: the user buffer
+ * @lenp: the size of the user buffer
+ * @ppos: file position
+ *
+ * Reads/writes a string from/to the user buffer. If the kernel
+ * buffer provided is not large enough to hold the string, the
+ * string is truncated. The copied string is %NULL-terminated.
+ * If the string is being read by the user process, it is copied
+ * and a newline '\n' is added. It is truncated if the buffer is
+ * not large enough.
+ *
+ * Returns 0 on success.
+ */
+int proc_dostring(ctl_table *table, int write, struct file *filp,
+		  void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	return _proc_do_string(table->data, table->maxlen, write, filp,
+			       buffer, lenp, ppos);
+}
+
 /*
  *	Special case of dostring for the UTS structure. This has locks
  *	to observe. Should this be in kernel/sys.c ????

>From sam.vilain@catalyst.net.nz Tue May 23 13:23:01 2006
From: Sam Vilain <sam.vilain@catalyst.net.nz>
Subject: [PATCH 3/3] proc: make UTS-related sysctls utsns aware
Date: Tue, 23 May 2006 13:23:01 +1200
To: ebiederm@xmission.com (Eric W. Biederman)
Cc: linux-kernel@vger.kernel.org, "Serge E. Hallyn" <serue@us.ibm.com>, herbert@13thfloor.at, dev@sw.ru, devel@openvz.org, sam@vilain.net, xemul@sw.ru, Dave Hansen <haveblue@us.ibm.com>, Andrew Morton <akpm@osdl.org>, Cedric Le Goater <clg@fr.ibm.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>
Message-Id: <20060523012301.13531.12776.stgit@localhost.localdomain>
In-Reply-To: <20060523012300.13531.96685.stgit@localhost.localdomain>
References: <20060523012300.13531.96685.stgit@localhost.localdomain>

From: Sam Vilain <sam.vilain@catalyst.net.nz>

Add a new function proc_do_utsns_string, that derives the pointer
into the uts_namespace->name structure, currently based on the
filename of the dentry in /proc, and calls _proc_do_string()
---
RFC only - not tested yet.  builds, though.

 kernel/sysctl.c |  104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 104 insertions(+), 0 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index cf053fc..37dc17f 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -141,8 +141,13 @@ #endif
 
 static int parse_table(int __user *, int, void __user *, size_t __user *, void __user *, size_t,
 		       ctl_table *, void **);
+#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);
+#else
+static int proc_do_utsns_string(ctl_table *table, int write, struct file *filp,
+		  void __user *buffer, size_t *lenp, loff_t *ppos);
+#endif
 
 static ctl_table root_table[];
 static struct ctl_table_header root_table_header =
@@ -238,6 +243,7 @@ #endif
 };
 
 static ctl_table kern_table[] = {
+#ifndef CONFIG_UTS_NS
 	{
 		.ctl_name	= KERN_OSTYPE,
 		.procname	= "ostype",
@@ -283,6 +289,54 @@ 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		= sizeof(current->nsproxy->uts_ns->name.sysname),
+		.mode		= 0444,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_OSRELEASE,
+		.procname	= "osrelease",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.release),
+		.mode		= 0444,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_VERSION,
+		.procname	= "version",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.version),
+		.mode		= 0444,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_NODENAME,
+		.procname	= "hostname",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.nodename),
+		.mode		= 0644,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_DOMAINNAME,
+		.procname	= "domainname",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.domainname),
+		.mode		= 0644,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+#endif /* !CONFIG_UTS_NS */
 	{
 		.ctl_name	= KERN_PANIC,
 		.procname	= "panic",
@@ -1684,6 +1738,7 @@ int proc_dostring(ctl_table *table, int 
  *	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)
 {
@@ -1700,6 +1755,55 @@ static int proc_do_uts_string(ctl_table 
 	}
 	return r;
 }
+#else /* !CONFIG_UTS_NS */
+static int proc_do_utsns_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;
+
+	/* map the filename to the pointer.  perhaps it would be better
+	   to put struct offset pointers in table->data ? */
+	switch (filp->f_dentry->d_name.name[3]) {
+		case 'y':  /* ostYpe */
+			which = uts_ns->name.sysname;
+			break;
+		case 't':  /* hosTname */
+			which = uts_ns->name.nodename;
+			break;
+		case 'e':  /* osrElease */
+			which = uts_ns->name.release;
+			break;
+		case 's':  /* verSion */
+			which = uts_ns->name.version;
+			break;
+		case 'x':  /* XXX - unreachable */
+			which = uts_ns->name.machine;
+			break;
+		case 'a':  /* domAinname */
+			which = uts_ns->name.domainname;
+			break;
+		default:
+			printk("procfs: impossible uts part '%s'",
+			       (char*)filp->f_dentry->d_name.name);
+			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,

[PATCH 3/3] proc: make UTS-related sysctls utsns aware

[Sam Vilain]

From: Sam Vilain <sam.vilain@catalyst.net.nz>

Add a new function proc_do_utsns_string, that derives the pointer
into the uts_namespace->name structure, currently based on the
filename of the dentry in /proc, and calls _proc_do_string()
---
RFC only - not tested yet.  builds, though.

 kernel/sysctl.c |  104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 104 insertions(+), 0 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index cf053fc..37dc17f 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -141,8 +141,13 @@ #endif
 
 static int parse_table(int __user *, int, void __user *, size_t __user *, void __user *, size_t,
 		       ctl_table *, void **);
+#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);
+#else
+static int proc_do_utsns_string(ctl_table *table, int write, struct file *filp,
+		  void __user *buffer, size_t *lenp, loff_t *ppos);
+#endif
 
 static ctl_table root_table[];
 static struct ctl_table_header root_table_header =
@@ -238,6 +243,7 @@ #endif
 };
 
 static ctl_table kern_table[] = {
+#ifndef CONFIG_UTS_NS
 	{
 		.ctl_name	= KERN_OSTYPE,
 		.procname	= "ostype",
@@ -283,6 +289,54 @@ 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		= sizeof(current->nsproxy->uts_ns->name.sysname),
+		.mode		= 0444,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_OSRELEASE,
+		.procname	= "osrelease",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.release),
+		.mode		= 0444,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_VERSION,
+		.procname	= "version",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.version),
+		.mode		= 0444,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_NODENAME,
+		.procname	= "hostname",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.nodename),
+		.mode		= 0644,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_DOMAINNAME,
+		.procname	= "domainname",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.domainname),
+		.mode		= 0644,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+#endif /* !CONFIG_UTS_NS */
 	{
 		.ctl_name	= KERN_PANIC,
 		.procname	= "panic",
@@ -1684,6 +1738,7 @@ int proc_dostring(ctl_table *table, int 
  *	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)
 {
@@ -1700,6 +1755,55 @@ static int proc_do_uts_string(ctl_table 
 	}
 	return r;
 }
+#else /* !CONFIG_UTS_NS */
+static int proc_do_utsns_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;
+
+	/* map the filename to the pointer.  perhaps it would be better
+	   to put struct offset pointers in table->data ? */
+	switch (filp->f_dentry->d_name.name[3]) {
+		case 'y':  /* ostYpe */
+			which = uts_ns->name.sysname;
+			break;
+		case 't':  /* hosTname */
+			which = uts_ns->name.nodename;
+			break;
+		case 'e':  /* osrElease */
+			which = uts_ns->name.release;
+			break;
+		case 's':  /* verSion */
+			which = uts_ns->name.version;
+			break;
+		case 'x':  /* XXX - unreachable */
+			which = uts_ns->name.machine;
+			break;
+		case 'a':  /* domAinname */
+			which = uts_ns->name.domainname;
+			break;
+		default:
+			printk("procfs: impossible uts part '%s'",
+			       (char*)filp->f_dentry->d_name.name);
+			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,

Re: [PATCH 3/3] proc: make UTS-related sysctls utsns aware

[Andrew Morton]

Sam Vilain <sam.vilain@catalyst.net.nz> wrote:
>
> Add a new function proc_do_utsns_string, that derives the pointer
>  into the uts_namespace->name structure, currently based on the
>  filename of the dentry in /proc, and calls _proc_do_string()
>  ---
>  RFC only - not tested yet.  builds, though

So... is it tested yet?

You owe me three Signed-off-by:s, please.

Re: [PATCH 3/3] proc: make UTS-related sysctls utsns aware

[Sam Vilain]

Andrew Morton wrote:
> Sam Vilain <sam.vilain@catalyst.net.nz> wrote:
> 
>>Add a new function proc_do_utsns_string, that derives the pointer
>> into the uts_namespace->name structure, currently based on the
>> filename of the dentry in /proc, and calls _proc_do_string()
>> ---
>> RFC only - not tested yet.  builds, though
> 
> 
> So... is it tested yet?

No, I was waiting for feedback

(hackhackhack)

ok, now it's tested

root@ken:~# ./chuts /bin/bash
root@ken:~# uname -a
Linux ken 2.6.17-rc4-mm2-g2214c350 #8 PREEMPT Thu May 25 09:32:27 NZST
2006 x86_64 GNU/Linux
root@ken:~# hostname bert
root@ken:~# uname -a
Linux bert 2.6.17-rc4-mm2-g2214c350 #8 PREEMPT Thu May 25 09:32:27 NZST
2006 x86_64 GNU/Linux
root@ken:~# exit
root@ken:~# uname -a
Linux ken 2.6.17-rc4-mm2-g2214c350 #8 PREEMPT Thu May 25 09:32:27 NZST
2006 x86_64 GNU/Linux
root@ken:~# cat /proc/sys/kernel/hostname
ken
root@ken:~# ./chuts /bin/sh -c "hostname bert && cat
/proc/sys/kernel/hostname"
bert
root@ken:~# cat /proc/sys/kernel/hostname
ken
root@ken:~# ./chuts /bin/sh -c "echo 'bob' > /proc/sys/kernel/hostname
&& uname -n"
bob
root@ken:~# uname -n
ken


> You owe me three Signed-off-by:s, please.

They should be coming your way seperately very shortly.  I've revised
the third one (namespaces-utsname-sysctl-hack-cleanup-2.patch), see my
reply to Dave Hansen's e-mail.  The revised version is the one I tested.
-- 
Sam Vilain, Catalyst IT (NZ) Ltd.
phone: +64 4 499 2267        cell:  +64 21 55 40 50
DDI:   +64 4 803 2342        PGP ID: 0x66B25843

Re: [PATCH 3/3] proc: make UTS-related sysctls utsns aware

[Dave Hansen]

On Tue, 2006-05-23 at 13:23 +1200, Sam Vilain wrote:
> 
> +       /* map the filename to the pointer.  perhaps it would be
> better
> +          to put struct offset pointers in table->data ? */
> +       switch (filp->f_dentry->d_name.name[3]) {
> +               case 'y':  /* ostYpe */
> +                       which = uts_ns->name.sysname;
> +                       break;
> +               case 't':  /* hosTname */
> +                       which = uts_ns->name.nodename;
> +                       break;
> +               case 'e':  /* osrElease */
> +                       which = uts_ns->name.release;
> +                       break;
> +               case 's':  /* verSion */
> +                       which = uts_ns->name.version;
> +                       break;
> +               case 'x':  /* XXX - unreachable */
> +                       which = uts_ns->name.machine;
> +                       break;
> +               case 'a':  /* domAinname */
> +                       which = uts_ns->name.domainname;
> +                       break;
> +               default:
> +                       printk("procfs: impossible uts part '%s'",
> +                              (char*)filp->f_dentry->d_name.name);
> +                       r = -EINVAL;
> +                       goto out;
> +       } 

Why not just switch on the ->ctl_name from the table?  Wouldn't that be
easier?

-- Dave

Re: [PATCH 3/3] proc: make UTS-related sysctls utsns aware

[Sam Vilain]

Dave Hansen wrote:
> On Tue, 2006-05-23 at 13:23 +1200, Sam Vilain wrote:
> 
> >> +       /* map the filename to the pointer.  perhaps it would be
> >> better
> >> +          to put struct offset pointers in table->data ? */
> >> +       switch (filp->f_dentry->d_name.name[3]) {
> >> +               case 'y':  /* ostYpe */
> >> +                       which = uts_ns->name.sysname;
> >> +                       break;
> 
> 
> Why not just switch on the ->ctl_name from the table?  Wouldn't that be
> easier?

Ha!  Sure would.

Subject: proc: make UTS-related sysctls utsns aware
From: Sam Vilain <sam.vilain@catalyst.net.nz>

Add a new function proc_do_utsns_string, that derives the pointer
into the uts_namespace->name structure, currently based on the
filename of the dentry in /proc, and calls _proc_do_string()

Signed-off-by: Sam Vilain <sam.vilain@catalyst.net.nz>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Andrey Savochkin <saw@sw.ru>
Cc: Andrew Morton <akpm@osdl.org>
---

 kernel/sysctl.c |   97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 97 insertions(+), 0 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index cf053fc..5e6837e 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -141,8 +141,13 @@ #endif
 
 static int parse_table(int __user *, int, void __user *, size_t __user *, void __user *, size_t,
 		       ctl_table *, void **);
+#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);
+#else
+static int proc_do_utsns_string(ctl_table *table, int write, struct file *filp,
+		  void __user *buffer, size_t *lenp, loff_t *ppos);
+#endif
 
 static ctl_table root_table[];
 static struct ctl_table_header root_table_header =
@@ -238,6 +243,7 @@ #endif
 };
 
 static ctl_table kern_table[] = {
+#ifndef CONFIG_UTS_NS
 	{
 		.ctl_name	= KERN_OSTYPE,
 		.procname	= "ostype",
@@ -283,6 +289,54 @@ 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		= sizeof(current->nsproxy->uts_ns->name.sysname),
+		.mode		= 0444,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_OSRELEASE,
+		.procname	= "osrelease",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.release),
+		.mode		= 0444,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_VERSION,
+		.procname	= "version",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.version),
+		.mode		= 0444,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_NODENAME,
+		.procname	= "hostname",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.nodename),
+		.mode		= 0644,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+	{
+		.ctl_name	= KERN_DOMAINNAME,
+		.procname	= "domainname",
+		.data		= NULL,
+		.maxlen		= sizeof(current->nsproxy->uts_ns->name.domainname),
+		.mode		= 0644,
+		.proc_handler	= &proc_do_utsns_string,
+		.strategy	= &sysctl_string,
+	},
+#endif /* !CONFIG_UTS_NS */
 	{
 		.ctl_name	= KERN_PANIC,
 		.procname	= "panic",
@@ -1684,6 +1738,7 @@ int proc_dostring(ctl_table *table, int 
  *	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)
 {
@@ -1700,6 +1755,48 @@ static int proc_do_uts_string(ctl_table 
 	}
 	return r;
 }
+#else /* !CONFIG_UTS_NS */
+static int proc_do_utsns_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,

[PATCH 2/3] proc: sysctl: add _proc_do_string helper

[Sam Vilain]

From: Sam Vilain <sam.vilain@catalyst.net.nz>

The logic in proc_do_string is worth re-using without passing in a
ctl_table structure (say, we want to calculate a pointer and pass that
in instead); pass in the two fields it uses from that structure
as explicit arguments.
---

 kernel/sysctl.c |   65 ++++++++++++++++++++++++++++++-------------------------
 1 files changed, 36 insertions(+), 29 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 618a2f8..cf053fc 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1605,32 +1605,14 @@ static ssize_t proc_writesys(struct file
 	return do_rw_proc(1, file, (char __user *) buf, count, ppos);
 }
 
-/**
- * proc_dostring - read a string sysctl
- * @table: the sysctl table
- * @write: %TRUE if this is a write to the sysctl file
- * @filp: the file structure
- * @buffer: the user buffer
- * @lenp: the size of the user buffer
- * @ppos: file position
- *
- * Reads/writes a string from/to the user buffer. If the kernel
- * buffer provided is not large enough to hold the string, the
- * string is truncated. The copied string is %NULL-terminated.
- * If the string is being read by the user process, it is copied
- * and a newline '\n' is added. It is truncated if the buffer is
- * not large enough.
- *
- * Returns 0 on success.
- */
-int proc_dostring(ctl_table *table, int write, struct file *filp,
-		  void __user *buffer, size_t *lenp, loff_t *ppos)
+int _proc_do_string(void* data, int maxlen, int write, struct file *filp,
+		    void __user *buffer, size_t *lenp, loff_t *ppos)
 {
 	size_t len;
 	char __user *p;
 	char c;
 	
-	if (!table->data || !table->maxlen || !*lenp ||
+	if (!data || !maxlen || !*lenp ||
 	    (*ppos && !write)) {
 		*lenp = 0;
 		return 0;
@@ -1646,20 +1628,20 @@ int proc_dostring(ctl_table *table, int 
 				break;
 			len++;
 		}
-		if (len >= table->maxlen)
-			len = table->maxlen-1;
-		if(copy_from_user(table->data, buffer, len))
+		if (len >= maxlen)
+			len = maxlen-1;
+		if(copy_from_user(data, buffer, len))
 			return -EFAULT;
-		((char *) table->data)[len] = 0;
+		((char *) data)[len] = 0;
 		*ppos += *lenp;
 	} else {
-		len = strlen(table->data);
-		if (len > table->maxlen)
-			len = table->maxlen;
+		len = strlen(data);
+		if (len > maxlen)
+			len = maxlen;
 		if (len > *lenp)
 			len = *lenp;
 		if (len)
-			if(copy_to_user(buffer, table->data, len))
+			if(copy_to_user(buffer, data, len))
 				return -EFAULT;
 		if (len < *lenp) {
 			if(put_user('\n', ((char __user *) buffer) + len))
@@ -1672,6 +1654,31 @@ int proc_dostring(ctl_table *table, int 
 	return 0;
 }
 
+/**
+ * proc_dostring - read a string sysctl
+ * @table: the sysctl table
+ * @write: %TRUE if this is a write to the sysctl file
+ * @filp: the file structure
+ * @buffer: the user buffer
+ * @lenp: the size of the user buffer
+ * @ppos: file position
+ *
+ * Reads/writes a string from/to the user buffer. If the kernel
+ * buffer provided is not large enough to hold the string, the
+ * string is truncated. The copied string is %NULL-terminated.
+ * If the string is being read by the user process, it is copied
+ * and a newline '\n' is added. It is truncated if the buffer is
+ * not large enough.
+ *
+ * Returns 0 on success.
+ */
+int proc_dostring(ctl_table *table, int write, struct file *filp,
+		  void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	return _proc_do_string(table->data, table->maxlen, write, filp,
+			       buffer, lenp, ppos);
+}
+
 /*
  *	Special case of dostring for the UTS structure. This has locks
  *	to observe. Should this be in kernel/sys.c ????