| 65b691f8 | 06-Feb-2026 |
Günther Noack <gnoack3000@gmail.com> |
landlock: Transpose the layer masks data structure
The layer masks data structure tracks the requested but unfulfilled
access rights during an operation's security check. It stores one bit
for each
landlock: Transpose the layer masks data structure
The layer masks data structure tracks the requested but unfulfilled
access rights during an operation's security check. It stores one bit
for each combination of access right and layer index. If the bit is
set, that access right is not granted (yet) in the given layer and we
have to traverse the path further upwards to grant it.
Previously, the layer masks were stored as arrays mapping from access
right indices to layer_mask_t. The layer_mask_t value then indicates
all layers in which the given access right is still (tentatively)
denied.
This patch introduces struct layer_access_masks instead: This struct
contains an array with the access_mask_t of each (tentatively) denied
access right in that layer.
The hypothesis of this patch is that this simplifies the code enough
so that the resulting code will run faster:
* We can use bitwise operations in multiple places where we previously
looped over bits individually with macros. (Should require less
branch speculation and lends itself to better loop unrolling.)
* Code is ~75 lines smaller.
Other noteworthy changes:
* In no_more_access(), call a new helper function may_refer(), which
only solves the asymmetric case. Previously, the code interleaved
the checks for the two symmetric cases in RENAME_EXCHANGE. It feels
that the code is clearer when renames without RENAME_EXCHANGE are
more obviously the normal case.
Tradeoffs:
This change improves performance, at a slight size increase to the
layer masks data structure.
This fixes the size of the data structure at 32 bytes for all types of
access rights. (64, once we introduce a 17th filesystem access right).
For filesystem access rights, at the moment, the data structure has
the same size as before, but once we introduce the 17th filesystem
access right, it will double in size (from 32 to 64 bytes), as
access_mask_t grows from 16 to 32 bit [1].
Link: https://lore.kernel.org/all/20260120.haeCh4li9Vae@digikod.net/ [1]
Signed-off-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20260206151154.97915-5-gnoack3000@gmail.com
[mic: Cosmetic fixes, moved struct layer_access_masks definition]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| fe72ce67 | 28-Jan-2026 |
Samasth Norway Ananda <samasth.norway.ananda@oracle.com> |
landlock: Add errata documentation section
Add errata section with code examples for querying errata and a warning
that most applications should not check errata. Use kernel-doc directives
to includ
landlock: Add errata documentation section
Add errata section with code examples for querying errata and a warning
that most applications should not check errata. Use kernel-doc directives
to include errata descriptions from the header files instead of manual
links.
Also enhance existing DOC sections in security/landlock/errata/abi-*.h
files with Impact sections, and update the code comment in syscalls.c
to remind developers to update errata documentation when applicable.
This addresses the gap where the kernel implements errata tracking
but provides no user-facing documentation on how to use it, while
improving the existing technical documentation in-place rather than
duplicating it.
Signed-off-by: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20260128031814.2945394-3-samasth.norway.ananda@oracle.com
[mic: Cosmetic fix]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| d90ba69e | 12-Dec-2025 |
Matthieu Buffet <matthieu@buffet.re> |
landlock: Refactor TCP socket type check
Move the socket type check earlier, so that we will later be able to add
elseifs for other types. Ordering of checks (socket is of a type we
enforce restrict
landlock: Refactor TCP socket type check
Move the socket type check earlier, so that we will later be able to add
elseifs for other types. Ordering of checks (socket is of a type we
enforce restrictions on) / (current creds have Landlock restrictions)
should not change anything.
Signed-off-by: Matthieu Buffet <matthieu@buffet.re>
Link: https://lore.kernel.org/r/20251212163704.142301-3-matthieu@buffet.re
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| ef4536f1 | 28-Dec-2025 |
Tingmao Wang <m@maowtm.org> |
landlock: Improve the comment for domain_is_scoped
Currently it is not obvious what "scoped" mean, and the fact that the
function returns true when access should be denied is slightly surprising
and
landlock: Improve the comment for domain_is_scoped
Currently it is not obvious what "scoped" mean, and the fact that the
function returns true when access should be denied is slightly surprising
and in need of documentation.
Cc: Tahera Fahimi <fahimitahera@gmail.com>
Signed-off-by: Tingmao Wang <m@maowtm.org>
Link: https://lore.kernel.org/r/06393bc18aee5bc278df5ef31c64a05b742ebc10.1766885035.git.m@maowtm.org
[mic: Fix formatting and improve consistency]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| 602acfb5 | 19-Dec-2025 |
Mickaël Salaün <mic@digikod.net> |
landlock: Optimize stack usage when !CONFIG_AUDIT
Until now, each landlock_request struct were allocated on the stack, even
if not really used, because is_access_to_paths_allowed() unconditionally
m
landlock: Optimize stack usage when !CONFIG_AUDIT
Until now, each landlock_request struct were allocated on the stack, even
if not really used, because is_access_to_paths_allowed() unconditionally
modified the passed references. Even if the changed landlock_request
variables are not used, the compiler is not smart enough to detect this
case.
To avoid this issue, explicitly disable the related code when
CONFIG_AUDIT is not set, which enables elision of log_request_parent*
and associated caller's stack variables thanks to dead code elimination.
This makes it possible to reduce the stack frame by 32 bytes for the
path_link and path_rename hooks, and by 20 bytes for most other
filesystem hooks.
Here is a summary of scripts/stackdelta before and after this change
when CONFIG_AUDIT is disabled:
current_check_refer_path 560 320 -240
current_check_access_path 328 184 -144
hook_file_open 328 184 -144
is_access_to_paths_allowed 376 360 -16
Also, add extra pointer checks to be more future-proof.
Cc: Günther Noack <gnoack@google.com>
Reported-by: Tingmao Wang <m@maowtm.org>
Closes: https://lore.kernel.org/r/eb86863b-53b0-460b-b223-84dd31d765b9@maowtm.org
Fixes: 2fc80c69df82 ("landlock: Log file-related denials")
Link: https://lore.kernel.org/r/20251219142302.744917-2-mic@digikod.net
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
[mic: Improve stack usage measurement accuracy with scripts/stackdelta]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| 6548fb52 | 19-Dec-2025 |
Mickaël Salaün <mic@digikod.net> |
landlock: Fix spelling
Cc: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20251219193855.825889-4-mic@digikod.net
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Signed-off-b
landlock: Fix spelling
Cc: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20251219193855.825889-4-mic@digikod.net
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| aa9877d7 | 19-Dec-2025 |
Mickaël Salaün <mic@digikod.net> |
landlock: Clean up hook_ptrace_access_check()
Make variable's scope minimal in hook_ptrace_access_check().
Cc: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20251219193855.82
landlock: Clean up hook_ptrace_access_check()
Make variable's scope minimal in hook_ptrace_access_check().
Cc: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20251219193855.825889-3-mic@digikod.net
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| 03a0ff99 | 19-Dec-2025 |
Mickaël Salaün <mic@digikod.net> |
landlock: Improve erratum documentation
Improve description about scoped signal handling.
Reported-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20251219193855.825889-2-m
landlock: Improve erratum documentation
Improve description about scoped signal handling.
Reported-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20251219193855.825889-2-mic@digikod.net
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| 60207df2 | 19-Dec-2025 |
Mickaël Salaün <mic@digikod.net> |
landlock: Remove useless include
Remove useless audit.h include.
Cc: Günther Noack <gnoack@google.com>
Fixes: 33e65b0d3add ("landlock: Add AUDIT_LANDLOCK_ACCESS and log ptrace denials")
Link: https
landlock: Remove useless include
Remove useless audit.h include.
Cc: Günther Noack <gnoack@google.com>
Fixes: 33e65b0d3add ("landlock: Add AUDIT_LANDLOCK_ACCESS and log ptrace denials")
Link: https://lore.kernel.org/r/20251219193855.825889-1-mic@digikod.net
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| 29fbfa46 | 06-Dec-2025 |
Tingmao Wang <m@maowtm.org> |
landlock: Fix wrong type usage
I think, based on my best understanding, that this type is likely a typo
(even though in the end both are u16)
Signed-off-by: Tingmao Wang <m@maowtm.org>
Fixes: 2fc80
landlock: Fix wrong type usage
I think, based on my best understanding, that this type is likely a typo
(even though in the end both are u16)
Signed-off-by: Tingmao Wang <m@maowtm.org>
Fixes: 2fc80c69df82 ("landlock: Log file-related denials")
Reviewed-by: Günther Noack <gnoack@google.com>
Link: https://lore.kernel.org/r/7339ad7b47f998affd84ca629a334a71f913616d.1765040503.git.m@maowtm.org
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| e4d82cbc | 27-Oct-2025 |
Matthieu Buffet <matthieu@buffet.re> |
landlock: Fix TCP handling of short AF_UNSPEC addresses
current_check_access_socket() treats AF_UNSPEC addresses as
AF_INET ones, and only later adds special case handling to
allow connect(AF_UNSPEC
landlock: Fix TCP handling of short AF_UNSPEC addresses
current_check_access_socket() treats AF_UNSPEC addresses as
AF_INET ones, and only later adds special case handling to
allow connect(AF_UNSPEC), and on IPv4 sockets
bind(AF_UNSPEC+INADDR_ANY).
This would be fine except AF_UNSPEC addresses can be as
short as a bare AF_UNSPEC sa_family_t field, and nothing
more. The AF_INET code path incorrectly enforces a length of
sizeof(struct sockaddr_in) instead.
Move AF_UNSPEC edge case handling up inside the switch-case,
before the address is (potentially incorrectly) treated as
AF_INET.
Fixes: fff69fb03dde ("landlock: Support network rules with TCP bind and connect")
Signed-off-by: Matthieu Buffet <matthieu@buffet.re>
Link: https://lore.kernel.org/r/20251027190726.626244-4-matthieu@buffet.re
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| f7ef7de6 | 28-Nov-2025 |
Mickaël Salaün <mic@digikod.net> |
landlock: Improve variable scope
This is now possible thanks to the disconnected directory fix.
Cc: Günther Noack <gnoack@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Tingmao Wang <m@maowtm.org>
landlock: Improve variable scope
This is now possible thanks to the disconnected directory fix.
Cc: Günther Noack <gnoack@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Tingmao Wang <m@maowtm.org>
Link: https://lore.kernel.org/r/20251128172200.760753-3-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|
| 49c9e09d | 28-Nov-2025 |
Mickaël Salaün <mic@digikod.net> |
landlock: Fix handling of disconnected directories
Disconnected files or directories can appear when they are visible and
opened from a bind mount, but have been renamed or moved from the source
of
landlock: Fix handling of disconnected directories
Disconnected files or directories can appear when they are visible and
opened from a bind mount, but have been renamed or moved from the source
of the bind mount in a way that makes them inaccessible from the mount
point (i.e. out of scope).
Previously, access rights tied to files or directories opened through a
disconnected directory were collected by walking the related hierarchy
down to the root of the filesystem, without taking into account the
mount point because it couldn't be found. This could lead to
inconsistent access results, potential access right widening, and
hard-to-debug renames, especially since such paths cannot be printed.
For a sandboxed task to create a disconnected directory, it needs to
have write access (i.e. FS_MAKE_REG, FS_REMOVE_FILE, and FS_REFER) to
the underlying source of the bind mount, and read access to the related
mount point. Because a sandboxed task cannot acquire more access
rights than those defined by its Landlock domain, this could lead to
inconsistent access rights due to missing permissions that should be
inherited from the mount point hierarchy, while inheriting permissions
from the filesystem hierarchy hidden by this mount point instead.
Landlock now handles files and directories opened from disconnected
directories by taking into account the filesystem hierarchy when the
mount point is not found in the hierarchy walk, and also always taking
into account the mount point from which these disconnected directories
were opened. This ensures that a rename is not allowed if it would
widen access rights [1].
The rationale is that, even if disconnected hierarchies might not be
visible or accessible to a sandboxed task, relying on the collected
access rights from them improves the guarantee that access rights will
not be widened during a rename because of the access right comparison
between the source and the destination (see LANDLOCK_ACCESS_FS_REFER).
It may look like this would grant more access on disconnected files and
directories, but the security policies are always enforced for all the
evaluated hierarchies. This new behavior should be less surprising to
users and safer from an access control perspective.
Remove a wrong WARN_ON_ONCE() canary in collect_domain_accesses() and
fix the related comment.
Because opened files have their access rights stored in the related file
security properties, there is no impact for disconnected or unlinked
files.
Cc: Christian Brauner <brauner@kernel.org>
Cc: Günther Noack <gnoack@google.com>
Cc: Song Liu <song@kernel.org>
Reported-by: Tingmao Wang <m@maowtm.org>
Closes: https://lore.kernel.org/r/027d5190-b37a-40a8-84e9-4ccbc352bcdf@maowtm.org
Closes: https://lore.kernel.org/r/09b24128f86973a6022e6aa8338945fcfb9a33e4.1749925391.git.m@maowtm.org
Fixes: b91c3e4ea756 ("landlock: Add support for file reparenting with LANDLOCK_ACCESS_FS_REFER")
Fixes: cb2c7d1a1776 ("landlock: Support filesystem access-control")
Link: https://lore.kernel.org/r/b0f46246-f2c5-42ca-93ce-0d629702a987@maowtm.org [1]
Reviewed-by: Tingmao Wang <m@maowtm.org>
Link: https://lore.kernel.org/r/20251128172200.760753-2-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
show more ...
|