Messages in this thread | | | Date | Thu, 17 Mar 2022 13:06:02 +0100 | From | Mickaël Salaün <> | Subject | Re: [PATCH v1 09/11] landlock: Document LANDLOCK_ACCESS_FS_REFER and ABI versioning |
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On 17/03/2022 02:27, Paul Moore wrote: > On Mon, Feb 21, 2022 at 4:15 PM Mickaël Salaün <mic@digikod.net> wrote: >> >> From: Mickaël Salaün <mic@linux.microsoft.com> >> >> Add LANDLOCK_ACCESS_FS_REFER in the example and properly check to only >> use it if the current kernel support it thanks to the Landlock ABI >> version. >> >> Move the file renaming and linking limitation to a new "Previous >> limitations" section. >> >> Improve documentation about the backward and forward compatibility, >> including the rational for ruleset's handled_access_fs. >> >> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> >> Link: https://lore.kernel.org/r/20220221212522.320243-10-mic@digikod.net >> --- >> Documentation/userspace-api/landlock.rst | 124 +++++++++++++++++++---- >> 1 file changed, 104 insertions(+), 20 deletions(-) > > Thanks for remembering to update the docs :) I made a few phrasing > suggestions below, but otherwise it looks good to me.
Thanks Paul! I'll take them.
> > Reviewed-by: Paul Moore <paul@paul-moore.com> > >> diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst >> index f35552ff19ba..97db09d36a5c 100644 >> --- a/Documentation/userspace-api/landlock.rst >> +++ b/Documentation/userspace-api/landlock.rst >> @@ -281,6 +347,24 @@ Memory usage >> Kernel memory allocated to create rulesets is accounted and can be restricted >> by the Documentation/admin-guide/cgroup-v1/memory.rst. >> >> +Previous limitations >> +==================== >> + >> +File renaming and linking (ABI 1) >> +--------------------------------- >> + >> +Because Landlock targets unprivileged access controls, it is needed to properly > ^^^^^ > "... controls, it needs to ..." > >> +handle composition of rules. Such property also implies rules nesting. >> +Properly handling multiple layers of ruleset, each one of them able to restrict > ^^^^^^^ > "rulesets," > >> +access to files, also implies to inherit the ruleset restrictions from a parent > ^^^^^^^^^^ > "... implies inheritance of the ..." > >> +to its hierarchy. Because files are identified and restricted by their >> +hierarchy, moving or linking a file from one directory to another implies to >> +propagate the hierarchy constraints. > > "... one directory to another implies propagation of the hierarchy constraints." > >> + To protect against privilege escalations > >> +through renaming or linking, and for the sake of simplicity, Landlock previously >> +limited linking and renaming to the same directory. Starting with the Landlock >> +ABI version 2, it is now possible to securely control renaming and linking >> +thanks to the new `LANDLOCK_ACCESS_FS_REFER` access right. > > -- > paul-moore.com
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