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

[Randy.Dunlap]

On Mon, 10 Jul 2006 16:38:59 -0600 Eric W. Biederman wrote:

> 
> 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.

Where is it documented and users notified that sys_sysctl is
deprecated?  Sounds like it should be added to
Documentation/feature-removal-schedule.txt.


> Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> ---
>  arch/ia64/ia32/sys_ia32.c         |    2 -
>  arch/mips/kernel/linux32.c        |    4 +
>  arch/powerpc/kernel/sys_ppc32.c   |    2 -
>  arch/s390/kernel/compat_linux.c   |    2 -
>  arch/sparc64/kernel/sys_sparc32.c |    2 -
>  arch/x86_64/ia32/sys_ia32.c       |    2 -
>  fs/Kconfig                        |   19 +++++++
>  init/Kconfig                      |   31 ++++++-----
>  kernel/sysctl.c                   |  101 ++++++++++---------------------------
>  9 files changed, 71 insertions(+), 94 deletions(-)
> 
> diff --git a/arch/ia64/ia32/sys_ia32.c b/arch/ia64/ia32/sys_ia32.c
> index 6aa3c51..bddbd22 100644
> --- a/arch/ia64/ia32/sys_ia32.c
> +++ b/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)
>  {
> diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
> index 814cb38..02eb78d 100644
> --- a/arch/mips/kernel/linux32.c
> +++ b/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 sysc
>  	return error;
>  }
>  
> -#endif /* CONFIG_SYSCTL */
> +#endif /* CONFIG_SYSCTL_SYSCALL */
>  
>  asmlinkage long sys32_newuname(struct new_utsname __user * name)
>  {
> diff --git a/arch/powerpc/kernel/sys_ppc32.c b/arch/powerpc/kernel/sys_ppc32.c
> index 2e29286..5e391fc 100644
> --- a/arch/powerpc/kernel/sys_ppc32.c
> +++ b/arch/powerpc/kernel/sys_ppc32.c
> @@ -740,7 +740,7 @@ asmlinkage long compat_sys_umask(u32 mas
>  	return sys_umask((int)mask);
>  }
>  
> -#ifdef CONFIG_SYSCTL
> +#ifdef CONFIG_SYSCTL_SYSCALL
>  struct __sysctl_args32 {
>  	u32 name;
>  	int nlen;
> diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
> index cabb4ff..4feadc4 100644
> --- a/arch/s390/kernel/compat_linux.c
> +++ b/arch/s390/kernel/compat_linux.c
> @@ -703,7 +703,7 @@ asmlinkage long sys32_sendfile64(int out
>  	return ret;
>  }
>  
> -#ifdef CONFIG_SYSCTL
> +#ifdef CONFIG_SYSCTL_SYSCALL
>  struct __sysctl_args32 {
>  	u32 name;
>  	int nlen;
> diff --git a/arch/sparc64/kernel/sys_sparc32.c b/arch/sparc64/kernel/sys_sparc32.c
> index c88ae23..69444f2 100644
> --- a/arch/sparc64/kernel/sys_sparc32.c
> +++ b/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;
> diff --git a/arch/x86_64/ia32/sys_ia32.c b/arch/x86_64/ia32/sys_ia32.c
> index b8424eb..ebd7873 100644
> --- a/arch/x86_64/ia32/sys_ia32.c
> +++ b/arch/x86_64/ia32/sys_ia32.c
> @@ -645,7 +645,7 @@ sys32_pause(void)
>  }
>  
>  
> -#ifdef CONFIG_SYSCTL
> +#ifdef CONFIG_SYSCTL_SYSCALL
>  struct sysctl_ia32 {
>  	unsigned int	name;
>  	int		nlen;
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 7532f00..b75cc54 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -829,6 +829,25 @@ 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
> diff --git a/init/Kconfig b/init/Kconfig
> index a1d7cc5..5949efb 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -213,21 +213,24 @@ config TASK_DELAY_ACCT
>  	  Say N if unsure.
>  
>  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 UTS_NS
>  	bool "UTS Namespaces"
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 5c4d19d..42610e6 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -140,8 +140,11 @@ #ifdef CONFIG_RT_MUTEXES
>  extern int max_lock_depth;
>  #endif
>  
> +#ifdef CONFIG_SYSCTL_SYSCALL
>  static int parse_table(int __user *, int, void __user *, size_t __user *, void __user *, size_t,
>  		       ctl_table *, void **);
> +#endif
> +
>  #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);
> @@ -173,7 +176,7 @@ #endif
>  
>  /* /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 *);
> @@ -1252,12 +1255,13 @@ static void start_unregistering(struct c
>  
>  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)
>  {
> @@ -1311,6 +1315,7 @@ asmlinkage long sys_sysctl(struct __sysc
>  	unlock_kernel();
>  	return error;
>  }
> +#endif /* CONFIG_SYSCTL_SYSCALL */
>  
>  /*
>   * ctl_perm does NOT grant the superuser all rights automatically, because
> @@ -1337,6 +1342,7 @@ static inline int ctl_perm(ctl_table *ta
>  	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,
> @@ -1426,6 +1432,7 @@ int do_sysctl_strategy (ctl_table *table
>  	}
>  	return 0;
>  }
> +#endif /* CONFIG_SYSCTL_SYSCALL */
>  
>  /**
>   * register_sysctl_table - register a sysctl hierarchy
> @@ -1513,7 +1520,7 @@ struct ctl_table_header *register_sysctl
>  	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;
> @@ -1531,18 +1538,31 @@ void unregister_sysctl_table(struct ctl_
>  	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)
> @@ -2520,6 +2540,7 @@ int proc_doulongvec_ms_jiffies_minmax(ct
>  #endif /* CONFIG_PROC_FS */
>  
>  
> +#ifdef CONFIG_SYSCTL_SYSCALL
>  /*
>   * General sysctl support routines 
>   */
> @@ -2662,7 +2683,7 @@ int sysctl_ms_jiffies(ctl_table *table, 
>  	return 1;
>  }
>  
> -#else /* CONFIG_SYSCTL */
> +#else /* CONFIG_SYSCTL_SYSCALL */
>  
>  
>  asmlinkage long sys_sysctl(struct __sysctl_args __user *args)
> @@ -2698,73 +2719,7 @@ int sysctl_ms_jiffies(ctl_table *table, 
>  	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,
> -- 

---
~Randy
-
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