[PATCH] sysctl: Allow /proc/sys without sys_sysctl

Since sys_sysctl is deprecated start allow it to be compiled out.  This
should catch any remaining user space code that cares, and paves the way
for further sysctl cleanups.

[[email protected]: If sys_sysctl() is not compiled-in, emit a warning]
Signed-off-by: Eric W. Biederman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

arch/ia64/ia32/sys_ia32.c

@@ -1942,7 +1942,7 @@ struct sysctl32 {
 	unsigned int	__unused[4];
 };
 
-#ifdef CONFIG_SYSCTL
+#ifdef CONFIG_SYSCTL_SYSCALL
 asmlinkage long
 sys32_sysctl (struct sysctl32 __user *args)
 {

arch/mips/kernel/linux32.c

@@ -991,7 +991,7 @@ struct sysctl_args32
 	unsigned int __unused[4];
 };
 
-#ifdef CONFIG_SYSCTL
+#ifdef CONFIG_SYSCTL_SYSCALL
 
 asmlinkage long sys32_sysctl(struct sysctl_args32 __user *args)
 {
@@ -1032,7 +1032,7 @@ asmlinkage long sys32_sysctl(struct sysctl_args32 __user *args)
 	return error;
 }
 
-#endif /* CONFIG_SYSCTL */
+#endif /* CONFIG_SYSCTL_SYSCALL */
 
 asmlinkage long sys32_newuname(struct new_utsname __user * name)
 {

arch/powerpc/kernel/sys_ppc32.c

@@ -740,7 +740,7 @@ asmlinkage long compat_sys_umask(u32 mask)
 	return sys_umask((int)mask);
 }
 
-#ifdef CONFIG_SYSCTL
+#ifdef CONFIG_SYSCTL_SYSCALL
 struct __sysctl_args32 {
 	u32 name;
 	int nlen;

arch/s390/kernel/compat_linux.c

@@ -708,7 +708,7 @@ asmlinkage long sys32_sendfile64(int out_fd, int in_fd,
 	return ret;
 }
 
-#ifdef CONFIG_SYSCTL
+#ifdef CONFIG_SYSCTL_SYSCALL
 struct __sysctl_args32 {
 	u32 name;
 	int nlen;

arch/sparc64/kernel/sys_sparc32.c

@@ -1016,7 +1016,7 @@ struct __sysctl_args32 {
 
 asmlinkage long sys32_sysctl(struct __sysctl_args32 __user *args)
 {
-#ifndef CONFIG_SYSCTL
+#ifndef CONFIG_SYSCTL_SYSCALL
 	return -ENOSYS;
 #else
 	struct __sysctl_args32 tmp;

arch/x86_64/ia32/sys_ia32.c

@@ -648,7 +648,7 @@ sys32_pause(void)
 }
 
 
-#ifdef CONFIG_SYSCTL
+#ifdef CONFIG_SYSCTL_SYSCALL
 struct sysctl_ia32 {
 	unsigned int	name;
 	int		nlen;

fs/Kconfig

@@ -826,6 +826,25 @@ config PROC_VMCORE
         help
         Exports the dump image of crashed kernel in ELF format.
 
+config PROC_SYSCTL
+	bool "Sysctl support (/proc/sys)" if EMBEDDED
+	depends on PROC_FS
+	select SYSCTL
+	default y
+	---help---
+	  The sysctl interface provides a means of dynamically changing
+	  certain kernel parameters and variables on the fly without requiring
+	  a recompile of the kernel or reboot of the system.  The primary
+	  interface is through /proc/sys.  If you say Y here a tree of
+	  modifiable sysctl entries will be generated beneath the
+          /proc/sys directory. They are explained in the files
+	  in <file:Documentation/sysctl/>.  Note that enabling this
+	  option will enlarge the kernel by at least 8 KB.
+
+	  As it is generally a good thing, you should say Y here unless
+	  building a kernel for install/rescue disks or your system is very
+	  limited in memory.
+
 config SYSFS
 	bool "sysfs file system support" if EMBEDDED
 	default y

init/Kconfig

@@ -273,21 +273,24 @@ config UID16
 	  This enables the legacy 16-bit UID syscall wrappers.
 
 config SYSCTL
-	bool "Sysctl support" if EMBEDDED
-	default y
+	bool
+
+config SYSCTL_SYSCALL
+	bool "Sysctl syscall support"
+	default n
+	select SYSCTL
 	---help---
-	  The sysctl interface provides a means of dynamically changing
-	  certain kernel parameters and variables on the fly without requiring
-	  a recompile of the kernel or reboot of the system.  The primary
-	  interface consists of a system call, but if you say Y to "/proc
-	  file system support", a tree of modifiable sysctl entries will be
-	  generated beneath the /proc/sys directory. They are explained in the
-	  files in <file:Documentation/sysctl/>.  Note that enabling this
-	  option will enlarge the kernel by at least 8 KB.
-
-	  As it is generally a good thing, you should say Y here unless
-	  building a kernel for install/rescue disks or your system is very
-	  limited in memory.
+	  Enable the deprecated sysctl system call.  sys_sysctl uses
+	  binary paths that have been found to be a major pain to maintain
+	  and use.  The interface in /proc/sys is now the primary and what
+	  everyone uses.
+
+	  Nothing has been using the binary sysctl interface for some time
+	  time now so nothing should break if you disable sysctl syscall
+	  support, and you kernel will get marginally smaller.
+
+	  Unless you have an application that uses the sys_syscall interface
+ 	  you should probably say N here.
 
 config KALLSYMS
 	 bool "Load all symbols for debugging/kksymoops" if EMBEDDED

kernel/sysctl.c

@@ -137,8 +137,11 @@ extern int no_unaligned_warning;
 extern int max_lock_depth;
 #endif
 
-static int parse_table(int __user *, int, void __user *, size_t __user *, void __user *, size_t,
-		       ctl_table *, void **);
+#ifdef CONFIG_SYSCTL_SYSCALL
+static int parse_table(int __user *, int, void __user *, size_t __user *,
+		void __user *, size_t, ctl_table *, void **);
+#endif
+
 static int proc_doutsstring(ctl_table *table, int write, struct file *filp,
 		  void __user *buffer, size_t *lenp, loff_t *ppos);
 
@@ -165,7 +168,7 @@ int sysctl_legacy_va_layout;
 
 /* /proc declarations: */
 
-#ifdef CONFIG_PROC_FS
+#ifdef CONFIG_PROC_SYSCTL
 
 static ssize_t proc_readsys(struct file *, char __user *, size_t, loff_t *);
 static ssize_t proc_writesys(struct file *, const char __user *, size_t, loff_t *);
@@ -1166,12 +1169,13 @@ static void start_unregistering(struct ctl_table_header *p)
 
 void __init sysctl_init(void)
 {
-#ifdef CONFIG_PROC_FS
+#ifdef CONFIG_PROC_SYSCTL
 	register_proc_table(root_table, proc_sys_root, &root_table_header);
 	init_irq_proc();
 #endif
 }
 
+#ifdef CONFIG_SYSCTL_SYSCALL
 int do_sysctl(int __user *name, int nlen, void __user *oldval, size_t __user *oldlenp,
 	       void __user *newval, size_t newlen)
 {
@@ -1225,6 +1229,7 @@ asmlinkage long sys_sysctl(struct __sysctl_args __user *args)
 	unlock_kernel();
 	return error;
 }
+#endif /* CONFIG_SYSCTL_SYSCALL */
 
 /*
  * ctl_perm does NOT grant the superuser all rights automatically, because
@@ -1251,6 +1256,7 @@ static inline int ctl_perm(ctl_table *table, int op)
 	return test_perm(table->mode, op);
 }
 
+#ifdef CONFIG_SYSCTL_SYSCALL
 static int parse_table(int __user *name, int nlen,
 		       void __user *oldval, size_t __user *oldlenp,
 		       void __user *newval, size_t newlen,
@@ -1340,6 +1346,7 @@ int do_sysctl_strategy (ctl_table *table,
 	}
 	return 0;
 }
+#endif /* CONFIG_SYSCTL_SYSCALL */
 
 /**
  * register_sysctl_table - register a sysctl hierarchy
@@ -1427,7 +1434,7 @@ struct ctl_table_header *register_sysctl_table(ctl_table * table,
 	else
 		list_add_tail(&tmp->ctl_entry, &root_table_header.ctl_entry);
 	spin_unlock(&sysctl_lock);
-#ifdef CONFIG_PROC_FS
+#ifdef CONFIG_PROC_SYSCTL
 	register_proc_table(table, proc_sys_root, tmp);
 #endif
 	return tmp;
@@ -1445,18 +1452,31 @@ void unregister_sysctl_table(struct ctl_table_header * header)
 	might_sleep();
 	spin_lock(&sysctl_lock);
 	start_unregistering(header);
-#ifdef CONFIG_PROC_FS
+#ifdef CONFIG_PROC_SYSCTL
 	unregister_proc_table(header->ctl_table, proc_sys_root);
 #endif
 	spin_unlock(&sysctl_lock);
 	kfree(header);
 }
 
+#else /* !CONFIG_SYSCTL */
+struct ctl_table_header * register_sysctl_table(ctl_table * table,
+						int insert_at_head)
+{
+	return NULL;
+}
+
+void unregister_sysctl_table(struct ctl_table_header * table)
+{
+}
+
+#endif /* CONFIG_SYSCTL */
+
 /*
  * /proc/sys support
  */
 
-#ifdef CONFIG_PROC_FS
+#ifdef CONFIG_PROC_SYSCTL
 
 /* Scan the sysctl entries in table and add them all into /proc */
 static void register_proc_table(ctl_table * table, struct proc_dir_entry *root, void *set)
@@ -2318,6 +2338,7 @@ int proc_doulongvec_ms_jiffies_minmax(ctl_table *table, int write,
 #endif /* CONFIG_PROC_FS */
 
 
+#ifdef CONFIG_SYSCTL_SYSCALL
 /*
  * General sysctl support routines 
  */
@@ -2460,11 +2481,19 @@ int sysctl_ms_jiffies(ctl_table *table, int __user *name, int nlen,
 	return 1;
 }
 
-#else /* CONFIG_SYSCTL */
+#else /* CONFIG_SYSCTL_SYSCALL */
 
 
 asmlinkage long sys_sysctl(struct __sysctl_args __user *args)
 {
+	static int msg_count;
+
+	if (msg_count < 5) {
+		msg_count++;
+		printk(KERN_INFO
+			"warning: process `%s' used the removed sysctl "
+			"system call\n", current->comm);
+	}
 	return -ENOSYS;
 }
 
@@ -2496,73 +2525,7 @@ int sysctl_ms_jiffies(ctl_table *table, int __user *name, int nlen,
 	return -ENOSYS;
 }
 
-int proc_dostring(ctl_table *table, int write, struct file *filp,
-		  void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-	return -ENOSYS;
-}
-
-int proc_dointvec(ctl_table *table, int write, struct file *filp,
-		  void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-	return -ENOSYS;
-}
-
-int proc_dointvec_bset(ctl_table *table, int write, struct file *filp,
-			void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-	return -ENOSYS;
-}
-
-int proc_dointvec_minmax(ctl_table *table, int write, struct file *filp,
-		    void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-	return -ENOSYS;
-}
-
-int proc_dointvec_jiffies(ctl_table *table, int write, struct file *filp,
-			  void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-	return -ENOSYS;
-}
-
-int proc_dointvec_userhz_jiffies(ctl_table *table, int write, struct file *filp,
-			  void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-	return -ENOSYS;
-}
-
-int proc_dointvec_ms_jiffies(ctl_table *table, int write, struct file *filp,
-			     void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-	return -ENOSYS;
-}
-
-int proc_doulongvec_minmax(ctl_table *table, int write, struct file *filp,
-		    void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-	return -ENOSYS;
-}
-
-int proc_doulongvec_ms_jiffies_minmax(ctl_table *table, int write,
-				      struct file *filp,
-				      void __user *buffer,
-				      size_t *lenp, loff_t *ppos)
-{
-    return -ENOSYS;
-}
-
-struct ctl_table_header * register_sysctl_table(ctl_table * table, 
-						int insert_at_head)
-{
-	return NULL;
-}
-
-void unregister_sysctl_table(struct ctl_table_header * table)
-{
-}
-
-#endif /* CONFIG_SYSCTL */
+#endif /* CONFIG_SYSCTL_SYSCALL */
 
 /*
  * No sense putting this after each symbol definition, twice,