Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi: "This update contains fixes to the "use mounter's permission to access underlying layers" area, and miscellaneous other fixes and cleanups. No new features this time" * 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: ovl: use vfs_get_link() vfs: add vfs_get_link() helper ovl: use generic_readlink ovl: explain error values when removing acl from workdir ovl: Fix info leak in ovl_lookup_temp() ovl: during copy up, switch to mounter's creds early ovl: lookup: do getxattr with mounter's permission ovl: copy_up_xattr(): use strnlen
This commit is contained in:
Linus Torvalds
Коммит
1a892b485f
25
fs/namei.c
25
fs/namei.c
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@ -4668,6 +4668,31 @@ int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
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}
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EXPORT_SYMBOL(generic_readlink);
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/**
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* vfs_get_link - get symlink body
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* @dentry: dentry on which to get symbolic link
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* @done: caller needs to free returned data with this
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*
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* Calls security hook and i_op->get_link() on the supplied inode.
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*
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* It does not touch atime. That's up to the caller if necessary.
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*
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* Does not work on "special" symlinks like /proc/$$/fd/N
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*/
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const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done)
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{
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const char *res = ERR_PTR(-EINVAL);
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struct inode *inode = d_inode(dentry);
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if (d_is_symlink(dentry)) {
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res = ERR_PTR(security_inode_readlink(dentry));
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if (!res)
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res = inode->i_op->get_link(dentry, inode, done);
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}
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return res;
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}
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EXPORT_SYMBOL(vfs_get_link);
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/* get the link contents into pagecache */
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const char *page_get_link(struct dentry *dentry, struct inode *inode,
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struct delayed_call *callback)
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@ -57,6 +57,7 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
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ssize_t list_size, size, value_size = 0;
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char *buf, *name, *value = NULL;
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int uninitialized_var(error);
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size_t slen;
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if (!(old->d_inode->i_opflags & IOP_XATTR) ||
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!(new->d_inode->i_opflags & IOP_XATTR))
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@ -79,7 +80,16 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
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goto out;
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}
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for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
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for (name = buf; list_size; name += slen) {
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slen = strnlen(name, list_size) + 1;
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/* underlying fs providing us with an broken xattr list? */
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if (WARN_ON(slen > list_size)) {
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error = -EIO;
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break;
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}
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list_size -= slen;
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if (ovl_is_private_xattr(name))
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continue;
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retry:
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@ -174,40 +184,6 @@ out_fput:
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return error;
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}
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static char *ovl_read_symlink(struct dentry *realdentry)
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{
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int res;
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char *buf;
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struct inode *inode = realdentry->d_inode;
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mm_segment_t old_fs;
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res = -EINVAL;
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if (!inode->i_op->readlink)
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goto err;
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res = -ENOMEM;
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buf = (char *) __get_free_page(GFP_KERNEL);
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if (!buf)
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goto err;
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old_fs = get_fs();
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set_fs(get_ds());
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/* The cast to a user pointer is valid due to the set_fs() */
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res = inode->i_op->readlink(realdentry,
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(char __user *)buf, PAGE_SIZE - 1);
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set_fs(old_fs);
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if (res < 0) {
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free_page((unsigned long) buf);
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goto err;
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}
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buf[res] = '\0';
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return buf;
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err:
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return ERR_PTR(res);
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}
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static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
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{
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struct iattr attr = {
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@ -354,19 +330,20 @@ out_cleanup:
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int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
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struct path *lowerpath, struct kstat *stat)
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{
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DEFINE_DELAYED_CALL(done);
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struct dentry *workdir = ovl_workdir(dentry);
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int err;
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struct kstat pstat;
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struct path parentpath;
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struct dentry *lowerdentry = lowerpath->dentry;
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struct dentry *upperdir;
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struct dentry *upperdentry;
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const struct cred *old_cred;
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char *link = NULL;
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const char *link = NULL;
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if (WARN_ON(!workdir))
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return -EROFS;
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ovl_do_check_copy_up(lowerpath->dentry);
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ovl_do_check_copy_up(lowerdentry);
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ovl_path_upper(parent, &parentpath);
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upperdir = parentpath.dentry;
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@ -376,13 +353,11 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
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return err;
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if (S_ISLNK(stat->mode)) {
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link = ovl_read_symlink(lowerpath->dentry);
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link = vfs_get_link(lowerdentry, &done);
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if (IS_ERR(link))
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return PTR_ERR(link);
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}
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old_cred = ovl_override_creds(dentry->d_sb);
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err = -EIO;
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if (lock_rename(workdir, upperdir) != NULL) {
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pr_err("overlayfs: failed to lock workdir+upperdir\n");
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@ -403,19 +378,16 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
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}
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out_unlock:
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unlock_rename(workdir, upperdir);
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revert_creds(old_cred);
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if (link)
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free_page((unsigned long) link);
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do_delayed_call(&done);
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return err;
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}
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int ovl_copy_up(struct dentry *dentry)
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{
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int err;
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int err = 0;
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const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
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err = 0;
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while (!err) {
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struct dentry *next;
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struct dentry *parent;
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@ -447,6 +419,7 @@ int ovl_copy_up(struct dentry *dentry)
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dput(parent);
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dput(next);
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}
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revert_creds(old_cred);
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return err;
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}
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@ -14,6 +14,7 @@
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#include <linux/cred.h>
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#include <linux/posix_acl.h>
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#include <linux/posix_acl_xattr.h>
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#include <linux/atomic.h>
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#include "overlayfs.h"
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void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
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@ -37,8 +38,10 @@ struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry)
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{
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struct dentry *temp;
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char name[20];
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static atomic_t temp_id = ATOMIC_INIT(0);
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snprintf(name, sizeof(name), "#%lx", (unsigned long) dentry);
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/* counter is allowed to wrap, since temp dentries are ephemeral */
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snprintf(name, sizeof(name), "#%x", atomic_inc_return(&temp_id));
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temp = lookup_one_len(name, workdir, strlen(name));
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if (!IS_ERR(temp) && temp->d_inode) {
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@ -19,6 +19,7 @@ static int ovl_copy_up_truncate(struct dentry *dentry)
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struct dentry *parent;
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struct kstat stat;
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struct path lowerpath;
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const struct cred *old_cred;
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parent = dget_parent(dentry);
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err = ovl_copy_up(parent);
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@ -26,12 +27,14 @@ static int ovl_copy_up_truncate(struct dentry *dentry)
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goto out_dput_parent;
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ovl_path_lower(dentry, &lowerpath);
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err = vfs_getattr(&lowerpath, &stat);
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if (err)
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goto out_dput_parent;
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stat.size = 0;
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err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);
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old_cred = ovl_override_creds(dentry->d_sb);
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err = vfs_getattr(&lowerpath, &stat);
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if (!err) {
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stat.size = 0;
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err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);
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}
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revert_creds(old_cred);
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out_dput_parent:
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dput(parent);
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@ -153,45 +156,18 @@ static const char *ovl_get_link(struct dentry *dentry,
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struct inode *inode,
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struct delayed_call *done)
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{
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struct dentry *realdentry;
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struct inode *realinode;
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const struct cred *old_cred;
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const char *p;
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if (!dentry)
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return ERR_PTR(-ECHILD);
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realdentry = ovl_dentry_real(dentry);
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realinode = realdentry->d_inode;
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if (WARN_ON(!realinode->i_op->get_link))
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return ERR_PTR(-EPERM);
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old_cred = ovl_override_creds(dentry->d_sb);
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p = realinode->i_op->get_link(realdentry, realinode, done);
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p = vfs_get_link(ovl_dentry_real(dentry), done);
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revert_creds(old_cred);
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return p;
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}
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static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
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{
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struct path realpath;
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struct inode *realinode;
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const struct cred *old_cred;
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int err;
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ovl_path_real(dentry, &realpath);
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realinode = realpath.dentry->d_inode;
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if (!realinode->i_op->readlink)
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return -EINVAL;
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old_cred = ovl_override_creds(dentry->d_sb);
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err = realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
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revert_creds(old_cred);
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return err;
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}
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bool ovl_is_private_xattr(const char *name)
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{
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return strncmp(name, OVL_XATTR_PREFIX,
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@ -375,7 +351,7 @@ static const struct inode_operations ovl_file_inode_operations = {
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static const struct inode_operations ovl_symlink_inode_operations = {
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.setattr = ovl_setattr,
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.get_link = ovl_get_link,
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.readlink = ovl_readlink,
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.readlink = generic_readlink,
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.getattr = ovl_getattr,
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.listxattr = ovl_listxattr,
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.update_time = ovl_update_time,
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@ -273,12 +273,11 @@ static bool ovl_is_opaquedir(struct dentry *dentry)
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{
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int res;
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char val;
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struct inode *inode = dentry->d_inode;
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if (!S_ISDIR(inode->i_mode) || !(inode->i_opflags & IOP_XATTR))
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if (!d_is_dir(dentry))
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return false;
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res = __vfs_getxattr(dentry, inode, OVL_XATTR_OPAQUE, &val, 1);
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res = vfs_getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1);
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if (res == 1 && val == 'y')
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return true;
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@ -419,16 +418,12 @@ static bool ovl_dentry_weird(struct dentry *dentry)
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DCACHE_OP_COMPARE);
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}
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static inline struct dentry *ovl_lookup_real(struct super_block *ovl_sb,
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struct dentry *dir,
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static inline struct dentry *ovl_lookup_real(struct dentry *dir,
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const struct qstr *name)
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{
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const struct cred *old_cred;
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struct dentry *dentry;
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old_cred = ovl_override_creds(ovl_sb);
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dentry = lookup_one_len_unlocked(name->name, dir, name->len);
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revert_creds(old_cred);
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if (IS_ERR(dentry)) {
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if (PTR_ERR(dentry) == -ENOENT)
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||||
|
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@ -469,6 +464,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
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|||
unsigned int flags)
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||||
{
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||||
struct ovl_entry *oe;
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||||
const struct cred *old_cred;
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||||
struct ovl_entry *poe = dentry->d_parent->d_fsdata;
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||||
struct path *stack = NULL;
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||||
struct dentry *upperdir, *upperdentry = NULL;
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||||
|
|
@ -479,9 +475,10 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
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|||
unsigned int i;
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||||
int err;
|
||||
|
||||
old_cred = ovl_override_creds(dentry->d_sb);
|
||||
upperdir = ovl_upperdentry_dereference(poe);
|
||||
if (upperdir) {
|
||||
this = ovl_lookup_real(dentry->d_sb, upperdir, &dentry->d_name);
|
||||
this = ovl_lookup_real(upperdir, &dentry->d_name);
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err = PTR_ERR(this);
|
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if (IS_ERR(this))
|
||||
goto out;
|
||||
|
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@ -514,8 +511,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
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bool opaque = false;
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struct path lowerpath = poe->lowerstack[i];
|
||||
|
||||
this = ovl_lookup_real(dentry->d_sb,
|
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lowerpath.dentry, &dentry->d_name);
|
||||
this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
|
||||
err = PTR_ERR(this);
|
||||
if (IS_ERR(this)) {
|
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/*
|
||||
|
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@ -588,6 +584,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
|
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ovl_copyattr(realdentry->d_inode, inode);
|
||||
}
|
||||
|
||||
revert_creds(old_cred);
|
||||
oe->opaque = upperopaque;
|
||||
oe->__upperdentry = upperdentry;
|
||||
memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
|
||||
|
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@ -606,6 +603,7 @@ out_put:
|
|||
out_put_upper:
|
||||
dput(upperdentry);
|
||||
out:
|
||||
revert_creds(old_cred);
|
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return ERR_PTR(err);
|
||||
}
|
||||
|
||||
|
|
@ -834,6 +832,19 @@ retry:
|
|||
if (err)
|
||||
goto out_dput;
|
||||
|
||||
/*
|
||||
* Try to remove POSIX ACL xattrs from workdir. We are good if:
|
||||
*
|
||||
* a) success (there was a POSIX ACL xattr and was removed)
|
||||
* b) -ENODATA (there was no POSIX ACL xattr)
|
||||
* c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
|
||||
*
|
||||
* There are various other error values that could effectively
|
||||
* mean that the xattr doesn't exist (e.g. -ERANGE is returned
|
||||
* if the xattr name is too long), but the set of filesystems
|
||||
* allowed as upper are limited to "normal" ones, where checking
|
||||
* for the above two errors is sufficient.
|
||||
*/
|
||||
err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT);
|
||||
if (err && err != -ENODATA && err != -EOPNOTSUPP)
|
||||
goto out_dput;
|
||||
|
|
|
|||
|
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@ -2934,6 +2934,7 @@ extern int vfs_stat(const char __user *, struct kstat *);
|
|||
extern int vfs_lstat(const char __user *, struct kstat *);
|
||||
extern int vfs_fstat(unsigned int, struct kstat *);
|
||||
extern int vfs_fstatat(int , const char __user *, struct kstat *, int);
|
||||
extern const char *vfs_get_link(struct dentry *, struct delayed_call *);
|
||||
|
||||
extern int __generic_block_fiemap(struct inode *inode,
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struct fiemap_extent_info *fieinfo,
|
||||
|
|
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