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ovl: switch to mounter creds in readdir

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In preparation for more permission checking, override credentials for
directory operations on the underlying filesystems.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi 2020-06-02 22:20:25 +02:00
parent 130fdbc3d1
commit 48bd024b8a
1 changed files with 21 additions and 6 deletions
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27
fs/overlayfs/readdir.c
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@ -743,8 +743,10 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
struct ovl_dir_file *od = file->private_data;
struct dentry *dentry = file->f_path.dentry;
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);
@ -758,17 +760,20 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
(ovl_same_fs(dentry->d_sb) &&
(ovl_is_impure_dir(file) ||
OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
return ovl_iterate_real(file, ctx);
err = ovl_iterate_real(file, ctx);
} else {
err = iterate_dir(od->realfile, ctx);
}
return iterate_dir(od->realfile, ctx);
goto out;
}
if (!od->cache) {
struct ovl_dir_cache *cache;
cache = ovl_cache_get(dentry);
err = PTR_ERR(cache);
if (IS_ERR(cache))
return PTR_ERR(cache);
goto out;
od->cache = cache;
ovl_seek_cursor(od, ctx->pos);
@ -780,7 +785,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
if (!p->ino) {
err = ovl_cache_update_ino(&file->f_path, p);
if (err)
return err;
goto out;
}
if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
break;
@ -788,7 +793,10 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
od->cursor = p->l_node.next;
ctx->pos++;
}
return 0;
err = 0;
out:
revert_creds(old_cred);
return err;
}
static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
@ -834,7 +842,14 @@ out_unlock:
static struct file *ovl_dir_open_realfile(struct file *file,
struct path *realpath)
{
return ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE));
struct file *res;
const struct cred *old_cred;
old_cred = ovl_override_creds(file_inode(file)->i_sb);
res = ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE));
revert_creds(old_cred);
return res;
}
static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,