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Kernel: Update intermediate nodes when changing unveil permissions

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When changing the unveil permissions of a preexisting node, we need to
make sure that any intermediate nodes that were created before and
should inherit permissions from the updated node are updated properly.

This fixes the following bug:
unveil("/home/anon/Documents", "r");
unveil("/home", "r");
Now there was a intermediate node for "/home/anon" which still had no
permission, even though it should have inherited the permissions from
"/home".
This commit is contained in:
Max Wipfli 2021-06-06 22:12:04 +02:00 • committed by Andreas Kling
parent 1e8006ebb8
commit 2fcebfd6a8
1 changed files with 19 additions and 0 deletions
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19
Kernel/Syscalls/unveil.cpp
View file

@ -13,6 +13,17 @@
namespace Kernel {
static void update_intermediate_node_permissions(UnveilNode& root_node, UnveilAccess new_permissions)
{
for (auto& entry : root_node.children()) {
auto& node = static_cast<UnveilNode&>(*entry.value);
if (node.was_explicitly_unveiled())
continue;
node.set_metadata({ node.path(), new_permissions, node.was_explicitly_unveiled() });
update_intermediate_node_permissions(node, new_permissions);
}
}
KResultOr<int> Process::sys$unveil(Userspace<const Syscall::SC_unveil_params*> user_params)
{
Syscall::SC_unveil_params params;
@ -96,6 +107,14 @@ KResultOr<int> Process::sys$unveil(Userspace<const Syscall::SC_unveil_params*> u
if (new_permissions & ~matching_node.permissions())
return EPERM;
}
// It is possible that nodes that are "grandchildren" of the matching node have already been unveiled.
// This means that there may be intermediate nodes between this one and the unveiled "grandchildren"
// that inherited the current node's previous permissions. Those nodes now need their permissions
// updated to match the current node.
if (matching_node.permissions() != new_permissions)
update_intermediate_node_permissions(matching_node, (UnveilAccess)new_permissions);
matching_node.set_metadata({ matching_node.path(), (UnveilAccess)new_permissions, true });
return 0;
}