On Wed, Oct 02, 2013 at 09:05:27AM -0700, Christoph Hellwig wrote:
> On Wed, Oct 02, 2013 at 10:25:27AM -0400, J. Bruce Fields wrote:
> > If so then it's no huge code duplication to it by hand:
> >
> > if (inode->i_op->getattr)
> > inode->i_op->getattr(path->mnt, path->dentry, &stat);
> > else
> > generic_fillattr(inode, &stat);
>
> Maybe make that a vfs_getattr_nosec and let vfs_getattr call it?
>
> Including a proper kerneldoc comment explaining when to use it, please.
Something like this?
--b.
commit 8418a41b7192cf2f372ae091207adb29a088f9a0
Author: J. Bruce Fields <bfields@xxxxxxxxxx>
Date: Tue Sep 10 11:41:12 2013 -0400
exportfs: fix 32-bit nfsd handling of 64-bit inode numbers
Symptoms were spurious -ENOENTs on stat of an NFS filesystem from a
32-bit NFS server exporting a very large XFS filesystem, when the
server's cache is cold (so the inodes in question are not in cache).
Reported-by: Trevor Cordes <trevor@xxxxxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 293bc2e..811831a 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -215,7 +215,7 @@ struct getdents_callback {
struct dir_context ctx;
char *name; /* name that was found. It already points to a
buffer NAME_MAX+1 is size */
- unsigned long ino; /* the inum we are looking for */
+ u64 ino; /* the inum we are looking for */
int found; /* inode matched? */
int sequence; /* sequence counter */
};
@@ -255,10 +255,10 @@ static int get_name(const struct path *path, char *name, struct dentry *child)
struct inode *dir = path->dentry->d_inode;
int error;
struct file *file;
+ struct kstat stat;
struct getdents_callback buffer = {
.ctx.actor = filldir_one,
.name = name,
- .ino = child->d_inode->i_ino
};
error = -ENOTDIR;
@@ -268,6 +268,16 @@ static int get_name(const struct path *path, char *name, struct dentry *child)
if (!dir->i_fop)
goto out;
/*
+ * inode->i_ino is unsigned long, kstat->ino is u64, so the
+ * former would be insufficient on 32-bit hosts when the
+ * filesystem supports 64-bit inode numbers. So we need to
+ * actually call ->getattr, not just read i_ino:
+ */
+ error = vfs_getattr_nosec(path, &stat);
+ if (error)
+ return error;
+ buffer.ino = stat.ino;
+ /*
* Open the directory ...
*/
file = dentry_open(path, O_RDONLY, cred);
diff --git a/fs/stat.c b/fs/stat.c
index 04ce1ac..71a39e8 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -37,14 +37,21 @@ void generic_fillattr(struct inode *inode, struct kstat *stat)
EXPORT_SYMBOL(generic_fillattr);
-int vfs_getattr(struct path *path, struct kstat *stat)
+/**
+ * vfs_getattr_nosec - getattr without security checks
+ * @path: file to get attributes from
+ * @stat: structure to return attributes in
+ *
+ * Get attributes without calling security_inode_getattr.
+ *
+ * Currently the only caller other than vfs_getattr is internal to the
+ * filehandle lookup code, which uses only the inode number and returns
+ * no attributes to any user. Any other code probably wants
+ * vfs_getattr.
+ */
+int vfs_getattr_nosec(struct path *path, struct kstat *stat)
{
struct inode *inode = path->dentry->d_inode;
- int retval;
-
- retval = security_inode_getattr(path->mnt, path->dentry);
- if (retval)
- return retval;
if (inode->i_op->getattr)
return inode->i_op->getattr(path->mnt, path->dentry, stat);
@@ -53,6 +60,18 @@ int vfs_getattr(struct path *path, struct kstat *stat)
return 0;
}
+EXPORT_SYMBOL_GPL(vfs_getattr_nosec);
+
+int vfs_getattr(struct path *path, struct kstat *stat)
+{
+ int retval;
+
+ retval = security_inode_getattr(path->mnt, path->dentry);
+ if (retval)
+ return retval;
+ return vfs_getattr_nosec(path, stat);
+}
+
EXPORT_SYMBOL(vfs_getattr);
int vfs_fstat(unsigned int fd, struct kstat *stat)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9818747..5a51faa 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2500,6 +2500,7 @@ extern int page_symlink(struct inode *inode, const char *symname, int len);
extern const struct inode_operations page_symlink_inode_operations;
extern int generic_readlink(struct dentry *, char __user *, int);
extern void generic_fillattr(struct inode *, struct kstat *);
+int vfs_getattr_nosec(struct path *path, struct kstat *stat);
extern int vfs_getattr(struct path *, struct kstat *);
void __inode_add_bytes(struct inode *inode, loff_t bytes);
void inode_add_bytes(struct inode *inode, loff_t bytes);
--
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