| Message ID | bbb4af1cb0933fea3307930a74258b8f78cba084.1722570749.git.fahimitahera@gmail.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | Landlock: Add abstract unix socket connect | expand |
On Thu, Aug 01, 2024 at 10:02:36PM -0600, Tahera Fahimi wrote: > Introducing LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET as an IPC scoping > mechanism in Landlock ABI version 6, and updating ruleset_attr, > Landlock ABI version, and access rights code blocks based on that. > > Signed-off-by: Tahera Fahimi <fahimitahera@gmail.com> > --- > v8: > - Improving documentation by specifying differences between scoped and > non-scoped domains. > - Adding review notes of version 7. > - Update date > v7: > - Add "LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET" explanation to IPC scoping > section and updating ABI to version 6. > - Adding "scoped" attribute to the Access rights section. > - In current limitation, unnamed sockets are specified as sockets that > are not restricted. > - Update date > --- > Documentation/userspace-api/landlock.rst | 33 ++++++++++++++++++++++-- > 1 file changed, 31 insertions(+), 2 deletions(-) > > diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst > index 07b63aec56fa..d602567b5139 100644 > --- a/Documentation/userspace-api/landlock.rst > +++ b/Documentation/userspace-api/landlock.rst > @@ -8,7 +8,7 @@ Landlock: unprivileged access control > ===================================== > > :Author: Mickaël Salaün > -:Date: April 2024 > +:Date: August 2024 > > The goal of Landlock is to enable to restrict ambient rights (e.g. global > filesystem or network access) for a set of processes. Because Landlock > @@ -81,6 +81,8 @@ to be explicit about the denied-by-default access rights. > .handled_access_net = > LANDLOCK_ACCESS_NET_BIND_TCP | > LANDLOCK_ACCESS_NET_CONNECT_TCP, > + .scoped = > + LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET, > }; > > Because we may not know on which kernel version an application will be > @@ -119,6 +121,9 @@ version, and only use the available subset of access rights: > case 4: > /* Removes LANDLOCK_ACCESS_FS_IOCTL_DEV for ABI < 5 */ > ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_IOCTL_DEV; > + case 5: > + /* Removes LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET for ABI < 6 */ > + ruleset_attr.scoped &= ~LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET; > } > > This enables to create an inclusive ruleset that will contain our rules. > @@ -306,6 +311,23 @@ To be allowed to use :manpage:`ptrace(2)` and related syscalls on a target > process, a sandboxed process should have a subset of the target process rules, > which means the tracee must be in a sub-domain of the tracer. > > +IPC Scoping > +----------- > + > +Similar to the implicit `Ptrace restrictions`_, we may want to further restrict > +interactions between sandboxes. Each Landlock domain can be explicitly scoped > +for a set of actions by specifying it on a ruleset. For example, if a sandboxed > +process should not be able to :manpage:`connect(2)` to a non-sandboxed process > +through abstract :manpage:`unix(7)` sockets, we can specify such restriction > +with ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET``. > + > +A sandboxed process can connect to a non-sandboxed process when its domain is > +not scoped. If a process's domain is scoped, it can only connect to processes in ...it can only connect to sockets created by proccesses in the same scoped domain. > +the same scoped domain. > + > +IPC scoping does not support Landlock rules, so if a domain is scoped, no rules > +can be added to allow accessing to a resource outside of the scoped domain. > + > Truncating files > ---------------- > > @@ -404,7 +426,7 @@ Access rights > ------------- > > .. kernel-doc:: include/uapi/linux/landlock.h > - :identifiers: fs_access net_access > + :identifiers: fs_access net_access scope > > Creating a new ruleset > ---------------------- > @@ -541,6 +563,13 @@ earlier ABI. > Starting with the Landlock ABI version 5, it is possible to restrict the use of > :manpage:`ioctl(2)` using the new ``LANDLOCK_ACCESS_FS_IOCTL_DEV`` right. > > +Abstract Unix sockets Restriction (ABI < 6) Let's follow the capitalization used by man pages: "UNIX" instead of "Unix". > +-------------------------------------------- > + > +With ABI version 6, it is possible to restrict connection to an abstract Unix socket > +through ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET``, thanks to the ``scoped`` ruleset > +attribute. > + > .. _kernel_support: > > Kernel support > -- > 2.34.1 >
diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst index 07b63aec56fa..d602567b5139 100644 --- a/Documentation/userspace-api/landlock.rst +++ b/Documentation/userspace-api/landlock.rst @@ -8,7 +8,7 @@ Landlock: unprivileged access control ===================================== :Author: Mickaël Salaün -:Date: April 2024 +:Date: August 2024 The goal of Landlock is to enable to restrict ambient rights (e.g. global filesystem or network access) for a set of processes. Because Landlock @@ -81,6 +81,8 @@ to be explicit about the denied-by-default access rights. .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP | LANDLOCK_ACCESS_NET_CONNECT_TCP, + .scoped = + LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET, }; Because we may not know on which kernel version an application will be @@ -119,6 +121,9 @@ version, and only use the available subset of access rights: case 4: /* Removes LANDLOCK_ACCESS_FS_IOCTL_DEV for ABI < 5 */ ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_IOCTL_DEV; + case 5: + /* Removes LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET for ABI < 6 */ + ruleset_attr.scoped &= ~LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET; } This enables to create an inclusive ruleset that will contain our rules. @@ -306,6 +311,23 @@ To be allowed to use :manpage:`ptrace(2)` and related syscalls on a target process, a sandboxed process should have a subset of the target process rules, which means the tracee must be in a sub-domain of the tracer. +IPC Scoping +----------- + +Similar to the implicit `Ptrace restrictions`_, we may want to further restrict +interactions between sandboxes. Each Landlock domain can be explicitly scoped +for a set of actions by specifying it on a ruleset. For example, if a sandboxed +process should not be able to :manpage:`connect(2)` to a non-sandboxed process +through abstract :manpage:`unix(7)` sockets, we can specify such restriction +with ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET``. + +A sandboxed process can connect to a non-sandboxed process when its domain is +not scoped. If a process's domain is scoped, it can only connect to processes in +the same scoped domain. + +IPC scoping does not support Landlock rules, so if a domain is scoped, no rules +can be added to allow accessing to a resource outside of the scoped domain. + Truncating files ---------------- @@ -404,7 +426,7 @@ Access rights ------------- .. kernel-doc:: include/uapi/linux/landlock.h - :identifiers: fs_access net_access + :identifiers: fs_access net_access scope Creating a new ruleset ---------------------- @@ -541,6 +563,13 @@ earlier ABI. Starting with the Landlock ABI version 5, it is possible to restrict the use of :manpage:`ioctl(2)` using the new ``LANDLOCK_ACCESS_FS_IOCTL_DEV`` right. +Abstract Unix sockets Restriction (ABI < 6) +-------------------------------------------- + +With ABI version 6, it is possible to restrict connection to an abstract Unix socket +through ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET``, thanks to the ``scoped`` ruleset +attribute. + .. _kernel_support: Kernel support
Introducing LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET as an IPC scoping mechanism in Landlock ABI version 6, and updating ruleset_attr, Landlock ABI version, and access rights code blocks based on that. Signed-off-by: Tahera Fahimi <fahimitahera@gmail.com> --- v8: - Improving documentation by specifying differences between scoped and non-scoped domains. - Adding review notes of version 7. - Update date v7: - Add "LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET" explanation to IPC scoping section and updating ABI to version 6. - Adding "scoped" attribute to the Access rights section. - In current limitation, unnamed sockets are specified as sockets that are not restricted. - Update date --- Documentation/userspace-api/landlock.rst | 33 ++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-)