[PATCH] add vfs_* helpers for xattr operations

Add vfs_getxattr, vfs_setxattr and vfs_removexattr helpers for common checks
around invocation of the xattr methods.  NFSD already was missing some of the
checks and there will be more soon.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: James Morris <jmorris@namei.org>

(James, I haven't touched selinux yet because it's doing various odd things
and I'm not sure how it would interact with the security attribute fallbacks
you added.  Could you investigate whether it could use vfs_getxattr or if not
add a __vfs_getxattr helper to share the bits it is fine with?)

For NFSv4: instead of just converting it add an nfsd_getxattr helper for the
code shared by NFSv2/3 and NFSv4 ACLs.  In fact that code isn't even
NFS-specific, but I'll wait for more users to pop up first before moving it to
common code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 93 insertions, 53 deletions

diff --git a/fs/xattr.c b/fs/xattr.c
index 386a532ee5a9..fee804e69a9a 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -19,6 +19,96 @@
 #include <linux/fsnotify.h>
 #include <asm/uaccess.h>
 
+
+int
+vfs_setxattr(struct dentry *dentry, char *name, void *value,
+                size_t size, int flags)
+{
+        struct inode *inode = dentry->d_inode;
+        int error;
+
+        mutex_lock(&inode->i_mutex);
+        error = security_inode_setxattr(dentry, name, value, size, flags);
+        if (error)
+                goto out;
+        error = -EOPNOTSUPP;
+        if (inode->i_op->setxattr) {
+                error = inode->i_op->setxattr(dentry, name, value, size, flags);
+                if (!error) {
+                        fsnotify_xattr(dentry);
+                        security_inode_post_setxattr(dentry, name, value,
+                                                     size, flags);
+                }
+        } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
+                                sizeof XATTR_SECURITY_PREFIX - 1)) {
+                const char *suffix = name + sizeof XATTR_SECURITY_PREFIX - 1;
+                error = security_inode_setsecurity(inode, suffix, value,
+                                                   size, flags);
+                if (!error)
+                        fsnotify_xattr(dentry);
+        }
+out:
+        mutex_unlock(&inode->i_mutex);
+        return error;
+}
+EXPORT_SYMBOL_GPL(vfs_setxattr);
+
+ssize_t
+vfs_getxattr(struct dentry *dentry, char *name, void *value, size_t size)
+{
+        struct inode *inode = dentry->d_inode;
+        int error;
+
+        error = security_inode_getxattr(dentry, name);
+        if (error)
+                return error;
+
+        if (inode->i_op->getxattr)
+                error = inode->i_op->getxattr(dentry, name, value, size);
+        else
+                error = -EOPNOTSUPP;
+
+        if (!strncmp(name, XATTR_SECURITY_PREFIX,
+                                sizeof XATTR_SECURITY_PREFIX - 1)) {
+                const char *suffix = name + sizeof XATTR_SECURITY_PREFIX - 1;
+                int ret = security_inode_getsecurity(inode, suffix, value,
+                                                     size, error);
+                /*
+                 * Only overwrite the return value if a security module
+                 * is actually active.
+                 */
+                if (ret != -EOPNOTSUPP)
+                        error = ret;
+        }
+
+        return error;
+}
+EXPORT_SYMBOL_GPL(vfs_getxattr);
+
+int
+vfs_removexattr(struct dentry *dentry, char *name)
+{
+        struct inode *inode = dentry->d_inode;
+        int error;
+
+        if (!inode->i_op->removexattr)
+                return -EOPNOTSUPP;
+
+        error = security_inode_removexattr(dentry, name);
+        if (error)
+                return error;
+
+        mutex_lock(&inode->i_mutex);
+        error = inode->i_op->removexattr(dentry, name);
+        mutex_unlock(&inode->i_mutex);
+
+        if (!error)
+                fsnotify_xattr(dentry);
+        return error;
+}
+EXPORT_SYMBOL_GPL(vfs_removexattr);
+
+
 /*
  * Extended attribute SET operations
  */
@@ -51,29 +141,7 @@ setxattr(struct dentry *d, char __user *name, void __user *value,
                 }
         }
 
-        mutex_lock(&d->d_inode->i_mutex);
-        error = security_inode_setxattr(d, kname, kvalue, size, flags);
-        if (error)
-                goto out;
-        error = -EOPNOTSUPP;
-        if (d->d_inode->i_op && d->d_inode->i_op->setxattr) {
-                error = d->d_inode->i_op->setxattr(d, kname, kvalue,
-                                                   size, flags);
-                if (!error) {
-                        fsnotify_xattr(d);
-                        security_inode_post_setxattr(d, kname, kvalue,
-                                                     size, flags);
-                }
-        } else if (!strncmp(kname, XATTR_SECURITY_PREFIX,
-                            sizeof XATTR_SECURITY_PREFIX - 1)) {
-                const char *suffix = kname + sizeof XATTR_SECURITY_PREFIX - 1;
-                error = security_inode_setsecurity(d->d_inode, suffix, kvalue,
-                                                   size, flags);
-                if (!error)
-                        fsnotify_xattr(d);
-        }
-out:
-        mutex_unlock(&d->d_inode->i_mutex);
+        error = vfs_setxattr(d, kname, kvalue, size, flags);
         kfree(kvalue);
         return error;
 }
@@ -147,22 +215,7 @@ getxattr(struct dentry *d, char __user *name, void __user *value, size_t size)
                         return -ENOMEM;
         }
 
-        error = security_inode_getxattr(d, kname);
-        if (error)
-                goto out;
-        error = -EOPNOTSUPP;
-        if (d->d_inode->i_op && d->d_inode->i_op->getxattr)
-                error = d->d_inode->i_op->getxattr(d, kname, kvalue, size);
-
-        if (!strncmp(kname, XATTR_SECURITY_PREFIX,
-                     sizeof XATTR_SECURITY_PREFIX - 1)) {
-                const char *suffix = kname + sizeof XATTR_SECURITY_PREFIX - 1;
-                int rv = security_inode_getsecurity(d->d_inode, suffix, kvalue,
-                                                    size, error);
-                /* Security module active: overwrite error value */
-                if (rv != -EOPNOTSUPP)
-                        error = rv;
-        }
+        error = vfs_getxattr(d, kname, kvalue, size);
         if (error > 0) {
                 if (size && copy_to_user(value, kvalue, error))
                         error = -EFAULT;
@@ -171,7 +224,6 @@ getxattr(struct dentry *d, char __user *name, void __user *value, size_t size)
                    than XATTR_SIZE_MAX bytes. Not possible. */
                 error = -E2BIG;
         }
-out:
         kfree(kvalue);
         return error;
 }
@@ -318,19 +370,7 @@ removexattr(struct dentry *d, char __user *name)
         if (error < 0)
                 return error;
 
-        error = -EOPNOTSUPP;
-        if (d->d_inode->i_op && d->d_inode->i_op->removexattr) {
-                error = security_inode_removexattr(d, kname);
-                if (error)
-                        goto out;
-                mutex_lock(&d->d_inode->i_mutex);
-                error = d->d_inode->i_op->removexattr(d, kname);
-                mutex_unlock(&d->d_inode->i_mutex);
-                if (!error)
-                        fsnotify_xattr(d);
-        }
-out:
-        return error;
+        return vfs_removexattr(d, kname);
 }
 
 asmlinkage long