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ovl: refactor ovl_iterate() and port to cred guard

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factor out ovl_iterate_merged() and move some code into
ovl_iterate_real() for easier use of the scoped ovl cred guard.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://patch.msgid.link/20251117-work-ovl-cred-guard-v4-25-b31603935724@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2025-11-17 10:33:56 +01:00
parent 198d182288
commit d25e4b739f
1 changed files with 45 additions and 31 deletions
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76
fs/overlayfs/readdir.c
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@@ -832,36 +832,12 @@ static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
return err;
}
static int ovl_iterate(struct file *file, struct dir_context *ctx)
static int ovl_iterate_merged(struct file *file, struct dir_context *ctx)
{
struct ovl_dir_file *od = file->private_data;
struct dentry *dentry = file->f_path.dentry;
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct ovl_cache_entry *p;
const struct cred *old_cred;
int err;
old_cred = ovl_override_creds(dentry->d_sb);
if (!ctx->pos)
ovl_dir_reset(file);
if (od->is_real) {
/*
* If parent is merge, then need to adjust d_ino for '..', if
* dir is impure then need to adjust d_ino for copied up
* entries.
*/
if (ovl_xino_bits(ofs) ||
(ovl_same_fs(ofs) &&
(ovl_is_impure_dir(file) ||
OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
err = ovl_iterate_real(file, ctx);
} else {
err = iterate_dir(od->realfile, ctx);
}
goto out;
}
int err = 0;
if (!od->cache) {
struct ovl_dir_cache *cache;
@@ -869,7 +845,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
cache = ovl_cache_get(dentry);
err = PTR_ERR(cache);
if (IS_ERR(cache))
goto out;
return err;
od->cache = cache;
ovl_seek_cursor(od, ctx->pos);
@@ -881,7 +857,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
if (!p->ino || p->check_xwhiteout) {
err = ovl_cache_update(&file->f_path, p, !p->ino);
if (err)
goto out;
return err;
}
}
/* ovl_cache_update() sets is_whiteout on stale entry */
@@ -892,12 +868,50 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
od->cursor = p->l_node.next;
ctx->pos++;
}
err = 0;
out:
ovl_revert_creds(old_cred);
return err;
}
static bool ovl_need_adjust_d_ino(struct file *file)
{
struct dentry *dentry = file->f_path.dentry;
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
/* If parent is merge, then need to adjust d_ino for '..' */
if (ovl_xino_bits(ofs))
return true;
/* Can't do consistent inode numbering */
if (!ovl_same_fs(ofs))
return false;
/* If dir is impure then need to adjust d_ino for copied up entries */
if (ovl_is_impure_dir(file) ||
OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent)))
return true;
/* Pure: no need to adjust d_ino */
return false;
}
static int ovl_iterate(struct file *file, struct dir_context *ctx)
{
struct ovl_dir_file *od = file->private_data;
if (!ctx->pos)
ovl_dir_reset(file);
with_ovl_creds(file_dentry(file)->d_sb) {
if (!od->is_real)
return ovl_iterate_merged(file, ctx);
if (ovl_need_adjust_d_ino(file))
return ovl_iterate_real(file, ctx);
return iterate_dir(od->realfile, ctx);
}
}
static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
{
loff_t res;