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fs: Better permission checking for submounts

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am: d3381fab77

Change-Id: I5f0019d2c86afd0a055f823f6751db9f6378e38f
This commit is contained in:
Eric W. Biederman
2017-03-15 02:22:24 +00:00
committed by android-build-merger
parent a2898ad07e d3381fab77
commit 5feec54044
13 changed files with 47 additions and 22 deletions
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fs/super.c
+10 -3
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@@ -470,7 +470,7 @@ struct super_block *sget_userns(struct file_system_type *type,
struct super_block *old;
int err;
if (!(flags & MS_KERNMOUNT) &&
if (!(flags & (MS_KERNMOUNT|MS_SUBMOUNT)) &&
!(type->fs_flags & FS_USERNS_MOUNT) &&
!capable(CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
@@ -500,7 +500,7 @@ retry:
}
if (!s) {
spin_unlock(&sb_lock);
s = alloc_super(type, flags, user_ns);
s = alloc_super(type, (flags & ~MS_SUBMOUNT), user_ns);
if (!s)
return ERR_PTR(-ENOMEM);
goto retry;
@@ -541,8 +541,15 @@ struct super_block *sget(struct file_system_type *type,
{
struct user_namespace *user_ns = current_user_ns();
/* We don't yet pass the user namespace of the parent
* mount through to here so always use &init_user_ns
* until that changes.
*/
if (flags & MS_SUBMOUNT)
user_ns = &init_user_ns;
/* Ensure the requestor has permissions over the target filesystem */
if (!(flags & MS_KERNMOUNT) && !ns_capable(user_ns, CAP_SYS_ADMIN))
if (!(flags & (MS_KERNMOUNT|MS_SUBMOUNT)) && !ns_capable(user_ns, CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
return sget_userns(type, test, set, flags, user_ns, data);