Summarize the rationale of filesystem access rights according to the
file type.
Update the document date.
Reviewed-by: Paul Moore <[email protected]>
Signed-off-by: Mickaël Salaün <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
Changes since v2:
* Add more explanation in the commit message.
* Update date.
Changes since v1:
* Add Reviewed-by: Paul Moore.
* Update date.
---
Documentation/security/landlock.rst | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/Documentation/security/landlock.rst b/Documentation/security/landlock.rst
index 3df68cb1d10f..5c77730b4479 100644
--- a/Documentation/security/landlock.rst
+++ b/Documentation/security/landlock.rst
@@ -7,7 +7,7 @@ Landlock LSM: kernel documentation
==================================
:Author: Mickaël Salaün
-:Date: March 2021
+:Date: May 2022
Landlock's goal is to create scoped access-control (i.e. sandboxing). To
harden a whole system, this feature should be available to any process,
@@ -42,6 +42,21 @@ Guiding principles for safe access controls
* Computation related to Landlock operations (e.g. enforcing a ruleset) shall
only impact the processes requesting them.
+Design choices
+==============
+
+Filesystem access rights
+------------------------
+
+All access rights are tied to an inode and what can be accessed through it.
+Reading the content of a directory doesn't imply to be allowed to read the
+content of a listed inode. Indeed, a file name is local to its parent
+directory, and an inode can be referenced by multiple file names thanks to
+(hard) links. Being able to unlink a file only has a direct impact on the
+directory, not the unlinked inode. This is the reason why
+`LANDLOCK_ACCESS_FS_REMOVE_FILE` or `LANDLOCK_ACCESS_FS_REFER` are not allowed
+to be tied to files but only to directories.
+
Tests
=====
--
2.35.1