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ovl: refactor ovl_rename()

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Extract the code that runs under overridden credentials into a separate
ovl_rename_upper() helper function and the code that runs before/after to
ovl_rename_start/end(). Error handling is simplified.
The helpers returns errors directly instead of using goto labels.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://patch.msgid.link/20251117-work-ovl-cred-guard-v4-34-b31603935724@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2025-11-19 20:48:38 +01:00
parent fb9f31fe9f
commit a1da840198
1 changed files with 78 additions and 57 deletions
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135
fs/overlayfs/dir.c
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@@ -1102,49 +1102,30 @@ struct ovl_renamedata {
bool overwrite;
};
static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
struct dentry *old, struct inode *newdir,
struct dentry *new, unsigned int flags)
static int ovl_rename_start(struct ovl_renamedata *ovlrd, struct list_head *list)
{
int err;
struct dentry *old_upperdir;
struct dentry *new_upperdir;
struct renamedata rd = {};
bool old_opaque;
bool new_opaque;
struct dentry *old = ovlrd->old_dentry;
struct dentry *new = ovlrd->new_dentry;
bool is_dir = d_is_dir(old);
bool new_is_dir = d_is_dir(new);
bool samedir = old->d_parent == new->d_parent;
struct dentry *whiteout = NULL;
const struct cred *old_cred = NULL;
struct ovl_fs *ofs = OVL_FS(old->d_sb);
struct ovl_renamedata _ovlrd = {
.old_dentry = old,
.new_dentry = new,
.flags = flags,
.cleanup_whiteout = false,
.overwrite = !(flags & RENAME_EXCHANGE),
};
struct ovl_renamedata *ovlrd = &_ovlrd;
LIST_HEAD(list);
int err;
err = -EINVAL;
if (ovlrd->flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
goto out;
return -EINVAL;
ovlrd->flags &= ~RENAME_NOREPLACE;
/* Don't copy up directory trees */
err = -EXDEV;
if (!ovl_can_move(old))
goto out;
return err;
if (!ovlrd->overwrite && !ovl_can_move(new))
goto out;
return err;
if (ovlrd->overwrite && new_is_dir && !ovl_pure_upper(new)) {
err = ovl_check_empty_dir(new, &list);
err = ovl_check_empty_dir(new, list);
if (err)
goto out;
return err;
}
if (ovlrd->overwrite) {
@@ -1164,19 +1145,20 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
err = ovl_copy_up(old);
if (err)
goto out;
return err;
err = ovl_copy_up(new->d_parent);
if (err)
goto out;
return err;
if (!ovlrd->overwrite) {
err = ovl_copy_up(new);
if (err)
goto out;
return err;
} else if (d_inode(new)) {
err = ovl_nlink_start(new);
if (err)
goto out;
return err;
ovlrd->update_nlink = true;
}
@@ -1185,23 +1167,35 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
/* ovl_nlink_start() took ovl_want_write() */
err = ovl_want_write(old);
if (err)
goto out;
return err;
}
old_cred = ovl_override_creds(old->d_sb);
return 0;
}
if (!list_empty(&list)) {
ovlrd->opaquedir = ovl_clear_empty(new, &list);
err = PTR_ERR(ovlrd->opaquedir);
if (IS_ERR(ovlrd->opaquedir)) {
ovlrd->opaquedir = NULL;
goto out_revert_creds;
}
static int ovl_rename_upper(struct ovl_renamedata *ovlrd, struct list_head *list)
{
struct dentry *old = ovlrd->old_dentry;
struct dentry *new = ovlrd->new_dentry;
struct ovl_fs *ofs = OVL_FS(old->d_sb);
struct dentry *old_upperdir = ovl_dentry_upper(old->d_parent);
struct dentry *new_upperdir = ovl_dentry_upper(new->d_parent);
bool is_dir = d_is_dir(old);
bool new_is_dir = d_is_dir(new);
bool samedir = old->d_parent == new->d_parent;
struct renamedata rd = {};
struct dentry *de;
struct dentry *whiteout = NULL;
bool old_opaque, new_opaque;
int err;
if (!list_empty(list)) {
de = ovl_clear_empty(new, list);
if (IS_ERR(de))
return PTR_ERR(de);
ovlrd->opaquedir = de;
}
old_upperdir = ovl_dentry_upper(old->d_parent);
new_upperdir = ovl_dentry_upper(new->d_parent);
if (!samedir) {
/*
* When moving a merge dir or non-dir with copy up origin into
@@ -1212,12 +1206,12 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
if (ovl_type_origin(old)) {
err = ovl_set_impure(new->d_parent, new_upperdir);
if (err)
goto out_revert_creds;
return err;
}
if (!ovlrd->overwrite && ovl_type_origin(new)) {
err = ovl_set_impure(old->d_parent, old_upperdir);
if (err)
goto out_revert_creds;
return err;
}
}
@@ -1229,9 +1223,8 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
err = start_renaming(&rd, 0,
&QSTR_LEN(old->d_name.name, old->d_name.len),
&QSTR_LEN(new->d_name.name, new->d_name.len));
if (err)
goto out_revert_creds;
return err;
err = -ESTALE;
if (!ovl_matches_upper(old, rd.old_dentry))
@@ -1283,10 +1276,11 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
if (!err && ovlrd->cleanup_whiteout)
whiteout = dget(rd.new_dentry);
out_unlock:
end_renaming(&rd);
if (err)
goto out_revert_creds;
return err;
if (whiteout) {
ovl_cleanup(ofs, old_upperdir, whiteout);
@@ -1310,20 +1304,47 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
if (d_inode(new) && ovl_dentry_upper(new))
ovl_copyattr(d_inode(new));
out_revert_creds:
ovl_revert_creds(old_cred);
return err;
}
static void ovl_rename_end(struct ovl_renamedata *ovlrd)
{
if (ovlrd->update_nlink)
ovl_nlink_end(new);
ovl_nlink_end(ovlrd->new_dentry);
else
ovl_drop_write(old);
ovl_drop_write(ovlrd->old_dentry);
}
static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
struct dentry *old, struct inode *newdir,
struct dentry *new, unsigned int flags)
{
const struct cred *old_cred = NULL;
struct ovl_renamedata ovlrd = {
.old_parent = old->d_parent,
.old_dentry = old,
.new_parent = new->d_parent,
.new_dentry = new,
.flags = flags,
.overwrite = !(flags & RENAME_EXCHANGE),
};
LIST_HEAD(list);
int err;
err = ovl_rename_start(&ovlrd, &list);
if (err)
goto out;
old_cred = ovl_override_creds(old->d_sb);
err = ovl_rename_upper(&ovlrd, &list);
ovl_revert_creds(old_cred);
ovl_rename_end(&ovlrd);
out:
dput(ovlrd->opaquedir);
ovl_cache_free(&list);
return err;
out_unlock:
end_renaming(&rd);
goto out_revert_creds;
}
static int ovl_create_tmpfile(struct file *file, struct dentry *dentry,