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authorMiklos Szeredi <mszeredi@redhat.com>2020-06-02 23:20:25 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2020-06-02 23:20:25 +0300
commit48bd024b8a40d73ad6b086de2615738da0c7004f (patch)
tree3dd927c460ac4a0a6a494c37b3abb2724ee0f5fb /fs/overlayfs
parent130fdbc3d1f9966dd4230709c30f3768bccd3065 (diff)
downloadlinux-48bd024b8a40d73ad6b086de2615738da0c7004f.tar.xz
ovl: switch to mounter creds in readdir
In preparation for more permission checking, override credentials for directory operations on the underlying filesystems. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs')
-rw-r--r--fs/overlayfs/readdir.c27
1 files changed, 21 insertions, 6 deletions
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 3bc97065cc70..1621460417be 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -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,