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path: root/fs/overlayfs/dir.c
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Diffstat (limited to 'fs/overlayfs/dir.c')
-rw-r--r--fs/overlayfs/dir.c152
1 files changed, 130 insertions, 22 deletions
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 0f8b4a719237..116f542442dd 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -14,6 +14,7 @@
#include <linux/posix_acl_xattr.h>
#include <linux/atomic.h>
#include <linux/ratelimit.h>
+#include <linux/backing-file.h>
#include "overlayfs.h"
static unsigned short ovl_redirect_max = 256;
@@ -260,14 +261,13 @@ static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
* may not use to instantiate the new dentry.
*/
static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
- struct dentry *newdentry, bool hardlink)
+ struct dentry *newdentry, bool hardlink, struct file *tmpfile)
{
struct ovl_inode_params oip = {
.upperdentry = newdentry,
.newinode = inode,
};
- ovl_dir_modified(dentry->d_parent, false);
ovl_dentry_set_upper_alias(dentry);
ovl_dentry_init_reval(dentry, newdentry, NULL);
@@ -295,6 +295,9 @@ static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
inc_nlink(inode);
}
+ if (tmpfile)
+ d_mark_tmpfile(tmpfile, inode);
+
d_instantiate(dentry, inode);
if (inode != oip.newinode) {
pr_warn_ratelimited("newly created inode found in cache (%pd2)\n",
@@ -327,9 +330,6 @@ static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
struct dentry *newdentry;
int err;
- if (!attr->hardlink && !IS_POSIXACL(udir))
- attr->mode &= ~current_umask();
-
inode_lock_nested(udir, I_MUTEX_PARENT);
newdentry = ovl_create_real(ofs, udir,
ovl_lookup_upper(ofs, dentry->d_name.name,
@@ -345,7 +345,8 @@ static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
ovl_set_opaque(dentry, newdentry);
}
- err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink);
+ ovl_dir_modified(dentry->d_parent, false);
+ err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink, NULL);
if (err)
goto out_cleanup;
out_unlock:
@@ -529,7 +530,8 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
if (err)
goto out_cleanup;
}
- err = ovl_instantiate(dentry, inode, newdentry, hardlink);
+ ovl_dir_modified(dentry->d_parent, false);
+ err = ovl_instantiate(dentry, inode, newdentry, hardlink, NULL);
if (err) {
ovl_cleanup(ofs, udir, newdentry);
dput(newdentry);
@@ -551,12 +553,35 @@ out_cleanup:
goto out_dput;
}
+static int ovl_setup_cred_for_create(struct dentry *dentry, struct inode *inode,
+ umode_t mode, const struct cred *old_cred)
+{
+ int err;
+ struct cred *override_cred;
+
+ override_cred = prepare_creds();
+ if (!override_cred)
+ return -ENOMEM;
+
+ override_cred->fsuid = inode->i_uid;
+ override_cred->fsgid = inode->i_gid;
+ err = security_dentry_create_files_as(dentry, mode, &dentry->d_name,
+ old_cred, override_cred);
+ if (err) {
+ put_cred(override_cred);
+ return err;
+ }
+ put_cred(override_creds(override_cred));
+ put_cred(override_cred);
+
+ return 0;
+}
+
static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
struct ovl_cattr *attr, bool origin)
{
int err;
const struct cred *old_cred;
- struct cred *override_cred;
struct dentry *parent = dentry->d_parent;
old_cred = ovl_override_creds(dentry->d_sb);
@@ -572,10 +597,6 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
}
if (!attr->hardlink) {
- err = -ENOMEM;
- override_cred = prepare_creds();
- if (!override_cred)
- goto out_revert_creds;
/*
* In the creation cases(create, mkdir, mknod, symlink),
* ovl should transfer current's fs{u,g}id to underlying
@@ -589,17 +610,9 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
* create a new inode, so just use the ovl mounter's
* fs{u,g}id.
*/
- override_cred->fsuid = inode->i_uid;
- override_cred->fsgid = inode->i_gid;
- err = security_dentry_create_files_as(dentry,
- attr->mode, &dentry->d_name, old_cred,
- override_cred);
- if (err) {
- put_cred(override_cred);
+ err = ovl_setup_cred_for_create(dentry, inode, attr->mode, old_cred);
+ if (err)
goto out_revert_creds;
- }
- put_cred(override_creds(override_cred));
- put_cred(override_cred);
}
if (!ovl_dentry_is_whiteout(dentry))
@@ -1290,6 +1303,100 @@ out:
return err;
}
+static int ovl_create_tmpfile(struct file *file, struct dentry *dentry,
+ struct inode *inode, umode_t mode)
+{
+ const struct cred *old_cred;
+ struct path realparentpath;
+ struct file *realfile;
+ struct dentry *newdentry;
+ /* It's okay to set O_NOATIME, since the owner will be current fsuid */
+ int flags = file->f_flags | OVL_OPEN_FLAGS;
+ int err;
+
+ err = ovl_copy_up(dentry->d_parent);
+ if (err)
+ return err;
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_setup_cred_for_create(dentry, inode, mode, old_cred);
+ if (err)
+ goto out_revert_creds;
+
+ ovl_path_upper(dentry->d_parent, &realparentpath);
+ realfile = backing_tmpfile_open(&file->f_path, flags, &realparentpath,
+ mode, current_cred());
+ err = PTR_ERR_OR_ZERO(realfile);
+ pr_debug("tmpfile/open(%pd2, 0%o) = %i\n", realparentpath.dentry, mode, err);
+ if (err)
+ goto out_revert_creds;
+
+ /* ovl_instantiate() consumes the newdentry reference on success */
+ newdentry = dget(realfile->f_path.dentry);
+ err = ovl_instantiate(dentry, inode, newdentry, false, file);
+ if (!err) {
+ file->private_data = realfile;
+ } else {
+ dput(newdentry);
+ fput(realfile);
+ }
+out_revert_creds:
+ revert_creds(old_cred);
+ return err;
+}
+
+static int ovl_dummy_open(struct inode *inode, struct file *file)
+{
+ return 0;
+}
+
+static int ovl_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
+ struct file *file, umode_t mode)
+{
+ int err;
+ struct dentry *dentry = file->f_path.dentry;
+ struct inode *inode;
+
+ if (!OVL_FS(dentry->d_sb)->tmpfile)
+ return -EOPNOTSUPP;
+
+ err = ovl_want_write(dentry);
+ if (err)
+ return err;
+
+ err = -ENOMEM;
+ inode = ovl_new_inode(dentry->d_sb, mode, 0);
+ if (!inode)
+ goto drop_write;
+
+ inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
+ err = ovl_create_tmpfile(file, dentry, inode, inode->i_mode);
+ if (err)
+ goto put_inode;
+
+ /*
+ * Check if the preallocated inode was actually used. Having something
+ * else assigned to the dentry shouldn't happen as that would indicate
+ * that the backing tmpfile "leaked" out of overlayfs.
+ */
+ err = -EIO;
+ if (WARN_ON(inode != d_inode(dentry)))
+ goto put_realfile;
+
+ /* inode reference was transferred to dentry */
+ inode = NULL;
+ err = finish_open(file, dentry, ovl_dummy_open);
+put_realfile:
+ /* Without FMODE_OPENED ->release() won't be called on @file */
+ if (!(file->f_mode & FMODE_OPENED))
+ fput(file->private_data);
+put_inode:
+ iput(inode);
+drop_write:
+ ovl_drop_write(dentry);
+ return err;
+}
+
const struct inode_operations ovl_dir_inode_operations = {
.lookup = ovl_lookup,
.mkdir = ovl_mkdir,
@@ -1310,4 +1417,5 @@ const struct inode_operations ovl_dir_inode_operations = {
.update_time = ovl_update_time,
.fileattr_get = ovl_fileattr_get,
.fileattr_set = ovl_fileattr_set,
+ .tmpfile = ovl_tmpfile,
};