Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst
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Add missing semicolon after EXPECT_EQ(0, close(stream_server_child)) in
the scoped_vs_unscoped test. I suspect currently it's just not executing
the close statement after the line, but this causes no observable
difference.
Fixes: fefcf0f7cf47 ("selftests/landlock: Test abstract UNIX socket scoping")
Cc: Tahera Fahimi <fahimitahera@gmail.com>
Signed-off-by: Tingmao Wang <m@maowtm.org>
Link: https://lore.kernel.org/r/d9e968e4cd4ecc9bf487593d7b7220bffbb3b5f5.1766885035.git.m@maowtm.org
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Signed-off-by: Tingmao Wang <m@maowtm.org>
Link: https://lore.kernel.org/r/62d18e06eeb26f62bc49d24c4467b3793c5ba32b.1766885035.git.m@maowtm.org
Signed-off-by: Mickaël Salaün <mic@digikod.net>
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>
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>
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>
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>
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>
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>
The size of Unix pathname addresses is computed in selftests using
offsetof(struct sockaddr_un, sun_path) + strlen(xxx). It should have
been that +1, which makes addresses passed to the libc and kernel
non-NULL-terminated. unix_mkname_bsd() fixes that in Linux so there is
no harm, but just using sizeof(the address struct) should improve
readability.
Signed-off-by: Matthieu Buffet <matthieu@buffet.re>
Reviewed-by: Günther Noack <gnoack@google.com>
Link: https://lore.kernel.org/r/20251202215141.689986-1-matthieu@buffet.re
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Remove bind() call on a client socket that doesn't make sense.
Since strlen(cli_un.sun_path) returns a random value depending on stack
garbage, that many uninitialized bytes are read from the stack as an
unix socket address. This creates random test failures due to the bind
address being invalid or already in use if the same stack value comes up
twice.
Fixes: f83d51a5bdfe ("selftests/landlock: Check IOCTL restrictions for named UNIX domain sockets")
Signed-off-by: Matthieu Buffet <matthieu@buffet.re>
Reviewed-by: Günther Noack <gnoack@google.com>
Link: https://lore.kernel.org/r/20251201003631.190817-1-matthieu@buffet.re
Signed-off-by: Mickaël Salaün <mic@digikod.net>
connect_variant(unspec_any0) is called twice. Both calls end
up in connect_variant_addrlen() with an address length of
get_addrlen(minimal=false).
However, the connect() syscall and its variants (e.g.
iouring/compat) accept much shorter addresses of 4 bytes
and that behaviour was not tested.
Replace one of these calls with one using a minimal address
length (just a bare sa_family=AF_UNSPEC field with no actual
address). Also add a call using a truncated address for good
measure.
Signed-off-by: Matthieu Buffet <matthieu@buffet.re>
Link: https://lore.kernel.org/r/20251027190726.626244-3-matthieu@buffet.re
Signed-off-by: Mickaël Salaün <mic@digikod.net>
The nominal error code for bind(AF_UNSPEC) on an IPv6 socket
is -EAFNOSUPPORT, not -EINVAL. -EINVAL is only returned when
the supplied address struct is too short, which happens to be
the case in current selftests because they treat AF_UNSPEC
like IPv4 sockets do: as an alias for AF_INET (which is a
16-byte struct instead of the 24 bytes required by IPv6
sockets).
Make the union large enough for any address (by adding struct
sockaddr_storage to the union), and make AF_UNSPEC addresses
large enough for any family.
Test for -EAFNOSUPPORT instead, and add a dedicated test case
for truncated inputs with -EINVAL.
Fixes: a549d055a22e ("selftests/landlock: Add network tests")
Signed-off-by: Matthieu Buffet <matthieu@buffet.re>
Link: https://lore.kernel.org/r/20251027190726.626244-2-matthieu@buffet.re
Signed-off-by: Mickaël Salaün <mic@digikod.net>
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>
Format with clang-format -i security/landlock/*.[ch]
Cc: Christian Brauner <brauner@kernel.org>
Cc: Günther Noack <gnoack3000@gmail.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Fixes: b4dbfd8653b3 ("Coccinelle-based conversion to use ->i_state accessors")
Link: https://lore.kernel.org/r/20251219193855.825889-5-mic@digikod.net
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Pull SCSI fixes from James Bottomley:
"The only core fix is in doc; all the others are in drivers, with the
biggest impacts in libsas being the rollback on error handling and in
ufs coming from a couple of error handling fixes, one causing a crash
if it's activated before scanning and the other fixing W-LUN
resumption"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: ufs: qcom: Fix confusing cleanup.h syntax
scsi: libsas: Add rollback handling when an error occurs
scsi: device_handler: Return error pointer in scsi_dh_attached_handler_name()
scsi: ufs: core: Fix a deadlock in the frequency scaling code
scsi: ufs: core: Fix an error handler crash
scsi: Revert "scsi: libsas: Fix exp-attached device scan after probe failure scanned in again after probe failed"
scsi: ufs: core: Fix RPMB link error by reversing Kconfig dependencies
scsi: qla4xxx: Use time conversion macros
scsi: qla2xxx: Enable/disable IRQD_NO_BALANCING during reset
scsi: ipr: Enable/disable IRQD_NO_BALANCING during reset
scsi: imm: Fix use-after-free bug caused by unfinished delayed work
scsi: target: sbp: Remove KMSG_COMPONENT macro
scsi: core: Correct documentation for scsi_device_quiesce()
scsi: mpi3mr: Prevent duplicate SAS/SATA device entries in channel 1
scsi: target: Reset t_task_cdb pointer in error case
scsi: ufs: core: Fix EH failure after W-LUN resume error