sys_sysfs: Add CONFIG_SYSFS_SYSCALL

sys_sysfs is an obsolete system call no longer supported by libc.

 - This patch adds a default CONFIG_SYSFS_SYSCALL=y

 - Option can be turned off in expert mode.

 - cond_syscall added to kernel/sys_ni.c

[akpm@linux-foundation.org: tweak Kconfig help text]
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 13 insertions, 0 deletions

diff --git a/fs/filesystems.c b/fs/filesystems.c
index 92567d95ba6a..5797d45a78cb 100644
--- a/fs/filesystems.c
+++ b/fs/filesystems.c
@@ -121,6 +121,7 @@ int unregister_filesystem(struct file_system_type * fs)
 
 EXPORT_SYMBOL(unregister_filesystem);
 
+#ifdef CONFIG_SYSFS_SYSCALL
 static int fs_index(const char __user * __name)
 {
         struct file_system_type * tmp;
@@ -199,6 +200,7 @@ SYSCALL_DEFINE3(sysfs, int, option, unsigned long, arg1, unsigned long, arg2)
         }
         return retval;
 }
+#endif
 
 int __init get_filesystem_list(char *buf)
 {
diff --git a/init/Kconfig b/init/Kconfig
index d56cb03c1b49..e45cc62904b3 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1290,6 +1290,16 @@ config UID16
         help
           This enables the legacy 16-bit UID syscall wrappers.
 
+config SYSFS_SYSCALL
+        bool "Sysfs syscall support" if EXPERT
+        default y
+        ---help---
+          sys_sysfs is an obsolete system call no longer supported in libc.
+          Note that disabling this option is more secure but might break
+          compatibility with some systems.
+
+          If unsure say Y here.
+
 config SYSCTL_SYSCALL
         bool "Sysctl syscall support" if EXPERT
         depends on PROC_SYSCTL
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 7078052284fd..74395a95b7e9 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -146,6 +146,7 @@ cond_syscall(sys_io_destroy);
 cond_syscall(sys_io_submit);
 cond_syscall(sys_io_cancel);
 cond_syscall(sys_io_getevents);
+cond_syscall(sys_sysfs);
 cond_syscall(sys_syslog);
 cond_syscall(sys_process_vm_readv);
 cond_syscall(sys_process_vm_writev);