fix: do not allow setting permissions for self

[RiccardoM]

Description

This PR changes how MsgSetUserPermissions is validated and how MsgSetUserGroupPermissions is handled to make sure a user cannot set their own permissions or the permissions of a group they are part of.

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[codecov]

Codecov Report

Merging #802 (52fcdc3) into master (3edee0a) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #802      +/-   ##
==========================================
+ Coverage   81.35%   81.41%   +0.06%     
==========================================
  Files          78       78              
  Lines        6681     6688       +7     
==========================================
+ Hits         5435     5445      +10     
+ Misses        995      993       -2     
+ Partials      251      250       -1     

Impacted Files	Coverage Δ
x/subspaces/keeper/msg_server.go	85.56% <100.00%> (+0.15%)	⬆️
x/subspaces/types/msgs.go	98.52% <100.00%> (+1.13%)	⬆️

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[manu0466]

@RiccardoM I think that there are other problems.
From spec a user can't give to other users the PermissionSetPermissions, this can be baypassed in this 3 cases:

Case 1

A user have the PermissionSetPermissions the he can just call SetUserPermissions and give to another user the PermissionSetPermissions

Case 2

• User UA have the PermissionManageGroups, then he create a new group with the defaultPermissions = PermissionSetPermissions
• Then he can add himelf to the group inheriting the PermissionSetPermissions

Case 3

• User UA sets default permissions of group GA to something that have PermissionSetPermissions, UA is not meber of the group.
• Then let's assume that UA have also the permissions PermissionManageGroups then he can add other users to the group giving them the PermissionSetPermission since all the members inherit the group permissions.

In all cases I don't see any checks that makes sure that only the subspace owner can give the SetUserPermissions in SetUserPermissions, CreateUserGroup, EditUserGroup.

[RiccardoM]

@manu0466 Let me answer you case by case

Case 1

A user have the PermissionSetPermissions the he can just call SetUserPermissions and give to another user the PermissionSetPermissions

This is the indented behavior. A subspace owner, which is the only initial user that can set permissions, should be very careful about giving out PermissionSetPermissions because the following might happen:

1. Alice gives PermissionSetPermissions to Bob
2. Bob created a new account, named Carl
3. Bob gives PermissionSetPermissions to another user

Unfortunately there is nothing we can do here. We should respect the choice of the subspace owner in this case and just allow them to do whatever they want. They can always decide to be the only one to give out permissions if they prefer. We just give options: it's up to them to use this feature or not.

Case 2

• User UA have the PermissionManageGroups, then he create a new group with the defaultPermissions = PermissionSetPermissions
• Then he can add himelf to the group inheriting the PermissionSetPermissions

This is actually a bug. I think it's better to open an issue about this and make sure during the handling of MsgCreateUserGroup that if DefaultPermissions contains PermissionSetPermissions, then the group owner must also have PermissionSetPermissions to avoid any trouble.

Case 3

• User UA sets default permissions of group GA to something that have PermissionSetPermissions, UA is not meber of the group.
• Then let's assume that UA have also the permissions PermissionManageGroups then he can add other users to the group giving them the PermissionSetPermission since all the members inherit the group permissions.

Actually, in order to add a user to a group you are required to have PermissionSetPermissions, not PermissionManageGroups. The latter is only checked when creating a group or editing an existing group. Also, editing user groups does not allow to set a new permission for the group itself. Groups permissions are only handled though MsgSetUserGroupPermissions which require PermissionSetPermissions.