Documentation/userspace-api/landlock.rst | 22 +- include/uapi/linux/landlock.h | 3 + samples/landlock/sandboxer.c | 17 +- security/landlock/fs.c | 17 + security/landlock/fs.h | 6 + security/landlock/limits.h | 2 +- security/landlock/task.c | 59 +++ .../selftests/landlock/scoped_signal_test.c | 371 ++++++++++++++++++ .../testing/selftests/landlock/scoped_test.c | 2 +- 9 files changed, 486 insertions(+), 13 deletions(-) create mode 100644 tools/testing/selftests/landlock/scoped_signal_test.c
This patch series adds scoping mechanism for signals.
Closes: https://github.com/landlock-lsm/linux/issues/8
Problem
=======
A sandboxed process is currently not restricted from sending signals
(e.g. SIGKILL) to processes outside the sandbox since Landlock has no
restriction on signals(see more details in [1]).
A simple way to apply this restriction would be to scope signals the
same way abstract unix sockets are restricted.
[1]https://lore.kernel.org/all/20231023.ahphah4Wii4v@digikod.net/
Solution
========
To solve this issue, we extend the "scoped" field in the Landlock
ruleset attribute structure by introducing "LANDLOCK_SCOPED_SIGNAL"
field to specify that a ruleset will deny sending any signals from
within the sandbox domain to its parent(i.e. any parent sandbox or
non-sandbox processes).
Example
=======
Create a sansboxed shell and pass the character "s" to LL_SCOPED:
LL_FD_RO=/ LL_FS_RW=. LL_SCOPED="s" ./sandboxer /bin/bash
Try to send a signal(like SIGTRAP) to a process ID <PID> through:
kill -SIGTRAP <PID>
The sandboxed process should not be able to send the signal.
Previous Versions
=================
v3:https://lore.kernel.org/all/cover.1723680305.git.fahimitahera@gmail.com/
v2:https://lore.kernel.org/all/cover.1722966592.git.fahimitahera@gmail.com/
v1:https://lore.kernel.org/all/cover.1720203255.git.fahimitahera@gmail.com/
Tahera Fahimi (6):
landlock: Add signal scoping control
selftest/landlock: Signal restriction tests
selftest/landlock: Add signal_scoping_threads test
selftest/landlock: Test file_send_sigiotask by sending out-of-bound
message
sample/landlock: Support sample for signal scoping restriction
landlock: Document LANDLOCK_SCOPED_SIGNAL
Documentation/userspace-api/landlock.rst | 22 +-
include/uapi/linux/landlock.h | 3 +
samples/landlock/sandboxer.c | 17 +-
security/landlock/fs.c | 17 +
security/landlock/fs.h | 6 +
security/landlock/limits.h | 2 +-
security/landlock/task.c | 59 +++
.../selftests/landlock/scoped_signal_test.c | 371 ++++++++++++++++++
.../testing/selftests/landlock/scoped_test.c | 2 +-
9 files changed, 486 insertions(+), 13 deletions(-)
create mode 100644 tools/testing/selftests/landlock/scoped_signal_test.c
--
2.34.1
We should also have the same tests as for scoped_vs_unscoped variants. I renamed them from the abstract unix socket patch series, please take a look: https://git.kernel.org/pub/scm/linux/kernel/git/mic/linux.git/log/?h=next I'll send more reviews tomorrow and I'll fix most of them in my -next branch (WIP), except for the hook_file_send_sigiotask tests and these scoped_vs_unscoped variants that you should resolve. On Fri, Sep 06, 2024 at 03:30:02PM -0600, Tahera Fahimi wrote: > This patch series adds scoping mechanism for signals. > Closes: https://github.com/landlock-lsm/linux/issues/8 > > Problem > ======= > > A sandboxed process is currently not restricted from sending signals > (e.g. SIGKILL) to processes outside the sandbox since Landlock has no > restriction on signals(see more details in [1]). > > A simple way to apply this restriction would be to scope signals the > same way abstract unix sockets are restricted. > > [1]https://lore.kernel.org/all/20231023.ahphah4Wii4v@digikod.net/ > > Solution > ======== > > To solve this issue, we extend the "scoped" field in the Landlock > ruleset attribute structure by introducing "LANDLOCK_SCOPED_SIGNAL" > field to specify that a ruleset will deny sending any signals from > within the sandbox domain to its parent(i.e. any parent sandbox or > non-sandbox processes). > > Example > ======= > > Create a sansboxed shell and pass the character "s" to LL_SCOPED: > LL_FD_RO=/ LL_FS_RW=. LL_SCOPED="s" ./sandboxer /bin/bash > Try to send a signal(like SIGTRAP) to a process ID <PID> through: > kill -SIGTRAP <PID> > The sandboxed process should not be able to send the signal. > > Previous Versions > ================= > v3:https://lore.kernel.org/all/cover.1723680305.git.fahimitahera@gmail.com/ > v2:https://lore.kernel.org/all/cover.1722966592.git.fahimitahera@gmail.com/ > v1:https://lore.kernel.org/all/cover.1720203255.git.fahimitahera@gmail.com/ > > Tahera Fahimi (6): > landlock: Add signal scoping control > selftest/landlock: Signal restriction tests > selftest/landlock: Add signal_scoping_threads test > selftest/landlock: Test file_send_sigiotask by sending out-of-bound > message > sample/landlock: Support sample for signal scoping restriction > landlock: Document LANDLOCK_SCOPED_SIGNAL > > Documentation/userspace-api/landlock.rst | 22 +- > include/uapi/linux/landlock.h | 3 + > samples/landlock/sandboxer.c | 17 +- > security/landlock/fs.c | 17 + > security/landlock/fs.h | 6 + > security/landlock/limits.h | 2 +- > security/landlock/task.c | 59 +++ > .../selftests/landlock/scoped_signal_test.c | 371 ++++++++++++++++++ > .../testing/selftests/landlock/scoped_test.c | 2 +- > 9 files changed, 486 insertions(+), 13 deletions(-) > create mode 100644 tools/testing/selftests/landlock/scoped_signal_test.c > > -- > 2.34.1 >
On Wed, Sep 11, 2024 at 08:17:04PM +0200, Mickaël Salaün wrote: > We should also have the same tests as for scoped_vs_unscoped variants. Hi, Thanks for the review, I will add them soon. > I renamed them from the abstract unix socket patch series, please take a > look: > https://git.kernel.org/pub/scm/linux/kernel/git/mic/linux.git/log/?h=next Wonderful! Thank you :) > I'll send more reviews tomorrow and I'll fix most of them in my -next > branch (WIP), except for the hook_file_send_sigiotask tests and these > scoped_vs_unscoped variants that you should resolve. I will keep an eye on reviews. What parts of hook_file_send_sigiotask would need changes? > On Fri, Sep 06, 2024 at 03:30:02PM -0600, Tahera Fahimi wrote: > > This patch series adds scoping mechanism for signals. > > Closes: https://github.com/landlock-lsm/linux/issues/8 > > > > Problem > > ======= > > > > A sandboxed process is currently not restricted from sending signals > > (e.g. SIGKILL) to processes outside the sandbox since Landlock has no > > restriction on signals(see more details in [1]). > > > > A simple way to apply this restriction would be to scope signals the > > same way abstract unix sockets are restricted. > > > > [1]https://lore.kernel.org/all/20231023.ahphah4Wii4v@digikod.net/ > > > > Solution > > ======== > > > > To solve this issue, we extend the "scoped" field in the Landlock > > ruleset attribute structure by introducing "LANDLOCK_SCOPED_SIGNAL" > > field to specify that a ruleset will deny sending any signals from > > within the sandbox domain to its parent(i.e. any parent sandbox or > > non-sandbox processes). > > > > Example > > ======= > > > > Create a sansboxed shell and pass the character "s" to LL_SCOPED: > > LL_FD_RO=/ LL_FS_RW=. LL_SCOPED="s" ./sandboxer /bin/bash > > Try to send a signal(like SIGTRAP) to a process ID <PID> through: > > kill -SIGTRAP <PID> > > The sandboxed process should not be able to send the signal. > > > > Previous Versions > > ================= > > v3:https://lore.kernel.org/all/cover.1723680305.git.fahimitahera@gmail.com/ > > v2:https://lore.kernel.org/all/cover.1722966592.git.fahimitahera@gmail.com/ > > v1:https://lore.kernel.org/all/cover.1720203255.git.fahimitahera@gmail.com/ > > > > Tahera Fahimi (6): > > landlock: Add signal scoping control > > selftest/landlock: Signal restriction tests > > selftest/landlock: Add signal_scoping_threads test > > selftest/landlock: Test file_send_sigiotask by sending out-of-bound > > message > > sample/landlock: Support sample for signal scoping restriction > > landlock: Document LANDLOCK_SCOPED_SIGNAL > > > > Documentation/userspace-api/landlock.rst | 22 +- > > include/uapi/linux/landlock.h | 3 + > > samples/landlock/sandboxer.c | 17 +- > > security/landlock/fs.c | 17 + > > security/landlock/fs.h | 6 + > > security/landlock/limits.h | 2 +- > > security/landlock/task.c | 59 +++ > > .../selftests/landlock/scoped_signal_test.c | 371 ++++++++++++++++++ > > .../testing/selftests/landlock/scoped_test.c | 2 +- > > 9 files changed, 486 insertions(+), 13 deletions(-) > > create mode 100644 tools/testing/selftests/landlock/scoped_signal_test.c > > > > -- > > 2.34.1 > >
On Wed, Sep 11, 2024 at 06:15:24PM -0600, Tahera Fahimi wrote: > On Wed, Sep 11, 2024 at 08:17:04PM +0200, Mickaël Salaün wrote: > > We should also have the same tests as for scoped_vs_unscoped variants. > Hi, > > Thanks for the review, I will add them soon. > > I renamed them from the abstract unix socket patch series, please take a > > look: > > https://git.kernel.org/pub/scm/linux/kernel/git/mic/linux.git/log/?h=next > Wonderful! Thank you :) > > > I'll send more reviews tomorrow and I'll fix most of them in my -next > > branch (WIP), except for the hook_file_send_sigiotask tests and these > > scoped_vs_unscoped variants that you should resolve. > I will keep an eye on reviews. What parts of hook_file_send_sigiotask > would need changes? The file_send_sigiotask hook was not fully covered. It's OK now, I reworked this test to fix that with four variants. You still need to work on the scoped_vs_unscoped tests for signaling though. > > > On Fri, Sep 06, 2024 at 03:30:02PM -0600, Tahera Fahimi wrote: > > > This patch series adds scoping mechanism for signals. > > > Closes: https://github.com/landlock-lsm/linux/issues/8 > > > > > > Problem > > > ======= > > > > > > A sandboxed process is currently not restricted from sending signals > > > (e.g. SIGKILL) to processes outside the sandbox since Landlock has no > > > restriction on signals(see more details in [1]). > > > > > > A simple way to apply this restriction would be to scope signals the > > > same way abstract unix sockets are restricted. > > > > > > [1]https://lore.kernel.org/all/20231023.ahphah4Wii4v@digikod.net/ > > > > > > Solution > > > ======== > > > > > > To solve this issue, we extend the "scoped" field in the Landlock > > > ruleset attribute structure by introducing "LANDLOCK_SCOPED_SIGNAL" > > > field to specify that a ruleset will deny sending any signals from > > > within the sandbox domain to its parent(i.e. any parent sandbox or > > > non-sandbox processes). > > > > > > Example > > > ======= > > > > > > Create a sansboxed shell and pass the character "s" to LL_SCOPED: > > > LL_FD_RO=/ LL_FS_RW=. LL_SCOPED="s" ./sandboxer /bin/bash > > > Try to send a signal(like SIGTRAP) to a process ID <PID> through: > > > kill -SIGTRAP <PID> > > > The sandboxed process should not be able to send the signal. > > > > > > Previous Versions > > > ================= > > > v3:https://lore.kernel.org/all/cover.1723680305.git.fahimitahera@gmail.com/ > > > v2:https://lore.kernel.org/all/cover.1722966592.git.fahimitahera@gmail.com/ > > > v1:https://lore.kernel.org/all/cover.1720203255.git.fahimitahera@gmail.com/ > > > > > > Tahera Fahimi (6): > > > landlock: Add signal scoping control > > > selftest/landlock: Signal restriction tests > > > selftest/landlock: Add signal_scoping_threads test > > > selftest/landlock: Test file_send_sigiotask by sending out-of-bound > > > message > > > sample/landlock: Support sample for signal scoping restriction > > > landlock: Document LANDLOCK_SCOPED_SIGNAL > > > > > > Documentation/userspace-api/landlock.rst | 22 +- > > > include/uapi/linux/landlock.h | 3 + > > > samples/landlock/sandboxer.c | 17 +- > > > security/landlock/fs.c | 17 + > > > security/landlock/fs.h | 6 + > > > security/landlock/limits.h | 2 +- > > > security/landlock/task.c | 59 +++ > > > .../selftests/landlock/scoped_signal_test.c | 371 ++++++++++++++++++ > > > .../testing/selftests/landlock/scoped_test.c | 2 +- > > > 9 files changed, 486 insertions(+), 13 deletions(-) > > > create mode 100644 tools/testing/selftests/landlock/scoped_signal_test.c > > > > > > -- > > > 2.34.1 > > > > >
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