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* Merge tag 'landlock-6.8-rc1' of ↵Linus Torvalds2024-01-091-13/+13
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux Pull Landlock updates from Mickaël Salaün: "New tests, a slight optimization, and some cosmetic changes" * tag 'landlock-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux: landlock: Optimize the number of calls to get_access_mask slightly selftests/landlock: Rename "permitted" to "allowed" in ftruncate tests landlock: Remove remaining "inline" modifiers in .c files [v6.6] landlock: Remove remaining "inline" modifiers in .c files [v6.1] landlock: Remove remaining "inline" modifiers in .c files [v5.15] selftests/landlock: Add tests to check unhandled rule's access rights selftests/landlock: Add tests to check unknown rule's access rights
| * landlock: Remove remaining "inline" modifiers in .c files [v6.6]Günther Noack2024-01-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | For module-internal static functions, compilers are already in a good position to decide whether to inline them or not. Suggested-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20231208155121.1943775-2-gnoack@google.com [mic: Split patch for Linux 6.6] Signed-off-by: Mickaël Salaün <mic@digikod.net>
| * landlock: Remove remaining "inline" modifiers in .c files [v6.1]Günther Noack2024-01-031-9/+9
| | | | | | | | | | | | | | | | | | | | | | For module-internal static functions, compilers are already in a good position to decide whether to inline them or not. Suggested-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20231208155121.1943775-2-gnoack@google.com [mic: Split patch for Linux 6.1] Signed-off-by: Mickaël Salaün <mic@digikod.net>
| * landlock: Remove remaining "inline" modifiers in .c files [v5.15]Günther Noack2024-01-031-3/+3
| | | | | | | | | | | | | | | | | | | | | | For module-internal static functions, compilers are already in a good position to decide whether to inline them or not. Suggested-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20231208155121.1943775-2-gnoack@google.com [mic: Split patch for Linux 5.15] Signed-off-by: Mickaël Salaün <mic@digikod.net>
* | LSM: Identify modules by more than nameCasey Schaufler2023-11-121-1/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Create a struct lsm_id to contain identifying information about Linux Security Modules (LSMs). At inception this contains the name of the module and an identifier associated with the security module. Change the security_add_hooks() interface to use this structure. Change the individual modules to maintain their own struct lsm_id and pass it to security_add_hooks(). The values are for LSM identifiers are defined in a new UAPI header file linux/lsm.h. Each existing LSM has been updated to include it's LSMID in the lsm_id. The LSM ID values are sequential, with the oldest module LSM_ID_CAPABILITY being the lowest value and the existing modules numbered in the order they were included in the main line kernel. This is an arbitrary convention for assigning the values, but none better presents itself. The value 0 is defined as being invalid. The values 1-99 are reserved for any special case uses which may arise in the future. This may include attributes of the LSM infrastructure itself, possibly related to namespacing or network attribute management. A special range is identified for such attributes to help reduce confusion for developers unfamiliar with LSMs. LSM attribute values are defined for the attributes presented by modules that are available today. As with the LSM IDs, The value 0 is defined as being invalid. The values 1-99 are reserved for any special case uses which may arise in the future. Cc: linux-security-module <linux-security-module@vger.kernel.org> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Serge Hallyn <serge@hallyn.com> Reviewed-by: Mickael Salaun <mic@digikod.net> Reviewed-by: John Johansen <john.johansen@canonical.com> Signed-off-by: Kees Cook <keescook@chromium.org> Nacked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> [PM: forward ported beyond v6.6 due merge window changes] Signed-off-by: Paul Moore <paul@paul-moore.com>
* landlock: Refactor layer helpersKonstantin Meskhidze2023-10-261-19/+24
| | | | | | | | | | | Add a new key_type argument to the landlock_init_layer_masks() helper. Add a masks_array_size argument to the landlock_unmask_layers() helper. These modifications support implementing new rule types in the next Landlock versions. Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> Link: https://lore.kernel.org/r/20231026014751.414649-7-konstantin.meskhidze@huawei.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Move and rename layer helpersKonstantin Meskhidze2023-10-261-115/+21
| | | | | | | | | | Move and rename landlock_unmask_layers() and landlock_init_layer_masks() helpers to ruleset.c to share them with Landlock network implementation in following commits. Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> Link: https://lore.kernel.org/r/20231026014751.414649-6-konstantin.meskhidze@huawei.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Refactor landlock_find_rule/insert_rule helpersKonstantin Meskhidze2023-10-261-8/+13
| | | | | | | | | | | | | | | | | | | | | Add a new landlock_key union and landlock_id structure to support a socket port rule type. A struct landlock_id identifies a unique entry in a ruleset: either a kernel object (e.g. inode) or typed data (e.g. TCP port). There is one red-black tree per key type. Add is_object_pointer() and get_root() helpers. is_object_pointer() returns true if key type is LANDLOCK_KEY_INODE. get_root() helper returns a red-black tree root pointer according to a key type. Refactor landlock_insert_rule() and landlock_find_rule() to support coming network modifications. Adding or searching a rule in ruleset can now be done thanks to a Landlock ID argument passed to these helpers. Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> Link: https://lore.kernel.org/r/20231026014751.414649-4-konstantin.meskhidze@huawei.com [mic: Fix commit message typo] Co-developed-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Allow FS topology changes for domains without such rule typeMickaël Salaün2023-10-261-37/+37
| | | | | | | | | | | | | | | | | Allow mount point and root directory changes when there is no filesystem rule tied to the current Landlock domain. This doesn't change anything for now because a domain must have at least a (filesystem) rule, but this will change when other rule types will come. For instance, a domain only restricting the network should have no impact on filesystem restrictions. Add a new get_current_fs_domain() helper to quickly check filesystem rule existence for all filesystem LSM hooks. Remove unnecessary inlining. Link: https://lore.kernel.org/r/20231026014751.414649-3-konstantin.meskhidze@huawei.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Make ruleset's access masks more genericKonstantin Meskhidze2023-10-261-5/+5
| | | | | | | | | | Rename ruleset's access masks and modify it's type to access_masks_t to support network type rules in following commits. Add filesystem helper functions to add and get filesystem mask. Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> Link: https://lore.kernel.org/r/20231026014751.414649-2-konstantin.meskhidze@huawei.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
* selinux: remove the runtime disable functionalityPaul Moore2023-03-201-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | After working with the larger SELinux-based distros for several years, we're finally at a place where we can disable the SELinux runtime disable functionality. The existing kernel deprecation notice explains the functionality and why we want to remove it: The selinuxfs "disable" node allows SELinux to be disabled at runtime prior to a policy being loaded into the kernel. If disabled via this mechanism, SELinux will remain disabled until the system is rebooted. The preferred method of disabling SELinux is via the "selinux=0" boot parameter, but the selinuxfs "disable" node was created to make it easier for systems with primitive bootloaders that did not allow for easy modification of the kernel command line. Unfortunately, allowing for SELinux to be disabled at runtime makes it difficult to secure the kernel's LSM hooks using the "__ro_after_init" feature. It is that last sentence, mentioning the '__ro_after_init' hardening, which is the real motivation for this change, and if you look at the diffstat you'll see that the impact of this patch reaches across all the different LSMs, helping prevent tampering at the LSM hook level. From a SELinux perspective, it is important to note that if you continue to disable SELinux via "/etc/selinux/config" it may appear that SELinux is disabled, but it is simply in an uninitialized state. If you load a policy with `load_policy -i`, you will see SELinux come alive just as if you had loaded the policy during early-boot. It is also worth noting that the "/sys/fs/selinux/disable" file is always writable now, regardless of the Kconfig settings, but writing to the file has no effect on the system, other than to display an error on the console if a non-zero/true value is written. Finally, in the several years where we have been working on deprecating this functionality, there has only been one instance of someone mentioning any user visible breakage. In this particular case it was an individual's kernel test system, and the workaround documented in the deprecation notice ("selinux=0" on the kernel command line) resolved the issue without problem. Acked-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
* landlock: Support file truncationGünther Noack2022-10-191-5/+99
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Introduce the LANDLOCK_ACCESS_FS_TRUNCATE flag for file truncation. This flag hooks into the path_truncate, file_truncate and file_alloc_security LSM hooks and covers file truncation using truncate(2), ftruncate(2), open(2) with O_TRUNC, as well as creat(). This change also increments the Landlock ABI version, updates corresponding selftests, and updates code documentation to document the flag. In security/security.c, allocate security blobs at pointer-aligned offsets. This fixes the problem where one LSM's security blob can shift another LSM's security blob to an unaligned address (reported by Nathan Chancellor). The following operations are restricted: open(2): requires the LANDLOCK_ACCESS_FS_TRUNCATE right if a file gets implicitly truncated as part of the open() (e.g. using O_TRUNC). Notable special cases: * open(..., O_RDONLY|O_TRUNC) can truncate files as well in Linux * open() with O_TRUNC does *not* need the TRUNCATE right when it creates a new file. truncate(2) (on a path): requires the LANDLOCK_ACCESS_FS_TRUNCATE right. ftruncate(2) (on a file): requires that the file had the TRUNCATE right when it was previously opened. File descriptors acquired by other means than open(2) (e.g. memfd_create(2)) continue to support truncation with ftruncate(2). Cc: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Günther Noack <gnoack3000@gmail.com> Acked-by: Paul Moore <paul@paul-moore.com> (LSM) Link: https://lore.kernel.org/r/20221018182216.301684-5-gnoack3000@gmail.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Document init_layer_masks() helperGünther Noack2022-10-191-0/+13
| | | | | | | | Add kernel-doc to the init_layer_masks() function. Signed-off-by: Günther Noack <gnoack3000@gmail.com> Link: https://lore.kernel.org/r/20221018182216.301684-4-gnoack3000@gmail.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Refactor check_access_path_dual() into is_access_to_paths_allowed()Günther Noack2022-10-191-45/+44
| | | | | | | | | | | | | Rename check_access_path_dual() to is_access_to_paths_allowed(). Make it return true iff the access is allowed. Calculate the EXDEV/EACCES error code in the one place where it's needed. Suggested-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Günther Noack <gnoack3000@gmail.com> Link: https://lore.kernel.org/r/20221018182216.301684-3-gnoack3000@gmail.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Slightly improve documentation and fix spellingMickaël Salaün2022-09-291-1/+1
| | | | | | | | | | | | | | | Now that we have more than one ABI version, make limitation explanation more consistent by replacing "ABI 1" with "ABI < 2". This also indicates which ABIs support such past limitation. Improve documentation consistency by not using contractions. Fix spelling in fs.c . Cc: Paul Moore <paul@paul-moore.com> Signed-off-by: Mickaël Salaün <mic@digikod.net> Reviewed-by: Günther Noack <gnoack3000@gmail.com> Link: https://lore.kernel.org/r/20220923154207.3311629-3-mic@digikod.net
* landlock: Fix file reparenting without explicit LANDLOCK_ACCESS_FS_REFERMickaël Salaün2022-09-021-23/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This change fixes a mis-handling of the LANDLOCK_ACCESS_FS_REFER right when multiple rulesets/domains are stacked. The expected behaviour was that an additional ruleset can only restrict the set of permitted operations, but in this particular case, it was potentially possible to re-gain the LANDLOCK_ACCESS_FS_REFER right. With the introduction of LANDLOCK_ACCESS_FS_REFER, we added the first globally denied-by-default access right. Indeed, this lifted an initial Landlock limitation to rename and link files, which was initially always denied when the source or the destination were different directories. This led to an inconsistent backward compatibility behavior which was only taken into account if no domain layer were using the new LANDLOCK_ACCESS_FS_REFER right. However, when restricting a thread with a new ruleset handling LANDLOCK_ACCESS_FS_REFER, all inherited parent rulesets/layers not explicitly handling LANDLOCK_ACCESS_FS_REFER would behave as if they were handling this access right and with all their rules allowing it. This means that renaming and linking files could became allowed by these parent layers, but all the other required accesses must also be granted: all layers must allow file removal or creation, and renaming and linking operations cannot lead to privilege escalation according to the Landlock policy. See detailed explanation in commit b91c3e4ea756 ("landlock: Add support for file reparenting with LANDLOCK_ACCESS_FS_REFER"). To say it another way, this bug may lift the renaming and linking limitations of the initial Landlock version, and a same ruleset can enforce different restrictions depending on previous or next enforced ruleset (i.e. inconsistent behavior). The LANDLOCK_ACCESS_FS_REFER right cannot give access to data not already allowed, but this doesn't follow the contract of the first Landlock ABI. This fix puts back the limitation for sandboxes that didn't opt-in for this additional right. For instance, if a first ruleset allows LANDLOCK_ACCESS_FS_MAKE_REG on /dst and LANDLOCK_ACCESS_FS_REMOVE_FILE on /src, renaming /src/file to /dst/file is denied. However, without this fix, stacking a new ruleset which allows LANDLOCK_ACCESS_FS_REFER on / would now permit the sandboxed thread to rename /src/file to /dst/file . This change fixes the (absolute) rule access rights, which now always forbid LANDLOCK_ACCESS_FS_REFER except when it is explicitly allowed when creating a rule. Making all domain handle LANDLOCK_ACCESS_FS_REFER was an initial approach but there is two downsides: * it makes the code more complex because we still want to check that a rule allowing LANDLOCK_ACCESS_FS_REFER is legitimate according to the ruleset's handled access rights (i.e. ABI v1 != ABI v2); * it would not allow to identify if the user created a ruleset explicitly handling LANDLOCK_ACCESS_FS_REFER or not, which will be an issue to audit Landlock. Instead, this change adds an ACCESS_INITIALLY_DENIED list of denied-by-default rights, which (only) contains LANDLOCK_ACCESS_FS_REFER. All domains are treated as if they are also handling this list, but without modifying their fs_access_masks field. A side effect is that the errno code returned by rename(2) or link(2) *may* be changed from EXDEV to EACCES according to the enforced restrictions. Indeed, we now have the mechanic to identify if an access is denied because of a required right (e.g. LANDLOCK_ACCESS_FS_MAKE_REG, LANDLOCK_ACCESS_FS_REMOVE_FILE) or if it is denied because of missing LANDLOCK_ACCESS_FS_REFER rights. This may result in different errno codes than for the initial Landlock version, but this approach is more consistent and better for rename/link compatibility reasons, and it wasn't possible before (hence no backport to ABI v1). The layout1.rename_file test reflects this change. Add 4 layout1.refer_denied_by_default* test suites to check that the behavior of a ruleset not handling LANDLOCK_ACCESS_FS_REFER (ABI v1) is unchanged even if another layer handles LANDLOCK_ACCESS_FS_REFER (i.e. ABI v1 precedence). Make sure rule's absolute access rights are correct by testing with and without a matching path. Add test_rename() and test_exchange() helpers. Extend layout1.inval tests to check that a denied-by-default access right is not necessarily part of a domain's handled access rights. Test coverage for security/landlock is 95.3% of 599 lines according to gcc/gcov-11. Fixes: b91c3e4ea756 ("landlock: Add support for file reparenting with LANDLOCK_ACCESS_FS_REFER") Reviewed-by: Paul Moore <paul@paul-moore.com> Reviewed-by: Günther Noack <gnoack3000@gmail.com> Link: https://lore.kernel.org/r/20220831203840.1370732-1-mic@digikod.net Cc: stable@vger.kernel.org [mic: Constify and slightly simplify test helpers] Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Add support for file reparenting with LANDLOCK_ACCESS_FS_REFERMickaël Salaün2022-05-231-74/+526
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add a new LANDLOCK_ACCESS_FS_REFER access right to enable policy writers to allow sandboxed processes to link and rename files from and to a specific set of file hierarchies. This access right should be composed with LANDLOCK_ACCESS_FS_MAKE_* for the destination of a link or rename, and with LANDLOCK_ACCESS_FS_REMOVE_* for a source of a rename. This lift a Landlock limitation that always denied changing the parent of an inode. Renaming or linking to the same directory is still always allowed, whatever LANDLOCK_ACCESS_FS_REFER is used or not, because it is not considered a threat to user data. However, creating multiple links or renaming to a different parent directory may lead to privilege escalations if not handled properly. Indeed, we must be sure that the source doesn't gain more privileges by being accessible from the destination. This is handled by making sure that the source hierarchy (including the referenced file or directory itself) restricts at least as much the destination hierarchy. If it is not the case, an EXDEV error is returned, making it potentially possible for user space to copy the file hierarchy instead of moving or linking it. Instead of creating different access rights for the source and the destination, we choose to make it simple and consistent for users. Indeed, considering the previous constraint, it would be weird to require such destination access right to be also granted to the source (to make it a superset). Moreover, RENAME_EXCHANGE would also add to the confusion because of paths being both a source and a destination. See the provided documentation for additional details. New tests are provided with a following commit. Reviewed-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Mickaël Salaün <mic@digikod.net> Link: https://lore.kernel.org/r/20220506161102.525323-8-mic@digikod.net
* LSM: Remove double path_rename hook calls for RENAME_EXCHANGEMickaël Salaün2022-05-231-1/+10
| | | | | | | | | | | | | | | | | | | | | | | | In order to be able to identify a file exchange with renameat2(2) and RENAME_EXCHANGE, which will be useful for Landlock [1], propagate the rename flags to LSMs. This may also improve performance because of the switch from two set of LSM hook calls to only one, and because LSMs using this hook may optimize the double check (e.g. only one lock, reduce the number of path walks). AppArmor, Landlock and Tomoyo are updated to leverage this change. This should not change the current behavior (same check order), except (different level of) speed boosts. [1] https://lore.kernel.org/r/20220221212522.320243-1-mic@digikod.net Cc: James Morris <jmorris@namei.org> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Serge E. Hallyn <serge@hallyn.com> Acked-by: John Johansen <john.johansen@canonical.com> Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reviewed-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Mickaël Salaün <mic@digikod.net> Link: https://lore.kernel.org/r/20220506161102.525323-7-mic@digikod.net
* landlock: Move filesystem helpers and add a new oneMickaël Salaün2022-05-231-41/+46
| | | | | | | | | | | | | Move the SB_NOUSER and IS_PRIVATE dentry check to a standalone is_nouser_or_private() helper. This will be useful for a following commit. Move get_mode_access() and maybe_remove() to make them usable by new code provided by a following commit. Reviewed-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Mickaël Salaün <mic@digikod.net> Link: https://lore.kernel.org/r/20220506161102.525323-6-mic@digikod.net
* landlock: Fix same-layer rule unionsMickaël Salaün2022-05-231-26/+52
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The original behavior was to check if the full set of requested accesses was allowed by at least a rule of every relevant layer. This didn't take into account requests for multiple accesses and same-layer rules allowing the union of these accesses in a complementary way. As a result, multiple accesses requested on a file hierarchy matching rules that, together, allowed these accesses, but without a unique rule allowing all of them, was illegitimately denied. This case should be rare in practice and it can only be triggered by the path_rename or file_open hook implementations. For instance, if, for the same layer, a rule allows execution beneath /a/b and another rule allows read beneath /a, requesting access to read and execute at the same time for /a/b should be allowed for this layer. This was an inconsistency because the union of same-layer rule accesses was already allowed if requested once at a time anyway. This fix changes the way allowed accesses are gathered over a path walk. To take into account all these rule accesses, we store in a matrix all layer granting the set of requested accesses, according to the handled accesses. To avoid heap allocation, we use an array on the stack which is 2*13 bytes. A following commit bringing the LANDLOCK_ACCESS_FS_REFER access right will increase this size to reach 112 bytes (2*14*4) in case of link or rename actions. Add a new layout1.layer_rule_unions test to check that accesses from different rules pertaining to the same layer are ORed in a file hierarchy. Also test that it is not the case for rules from different layers. Reviewed-by: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/r/20220506161102.525323-5-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Create find_rule() from unmask_layers()Mickaël Salaün2022-05-231-13/+28
| | | | | | | | | This refactoring will be useful in a following commit. Reviewed-by: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/r/20220506161102.525323-4-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Reduce the maximum number of layers to 16Mickaël Salaün2022-05-231-10/+7
| | | | | | | | | | | | | | | | | | The maximum number of nested Landlock domains is currently 64. Because of the following fix and to help reduce the stack size, let's reduce it to 16. This seems large enough for a lot of use cases (e.g. sandboxed init service, spawning a sandboxed SSH service, in nested sandboxed containers). Reducing the number of nested domains may also help to discover misuse of Landlock (e.g. creating a domain per rule). Add and use a dedicated layer_mask_t typedef to fit with the number of layers. This might be useful when changing it and to keep it consistent with the maximum number of layers. Reviewed-by: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/r/20220506161102.525323-3-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Define access_mask_t to enforce a consistent access mask sizeMickaël Salaün2022-05-231-8/+11
| | | | | | | | | | | | | | Create and use the access_mask_t typedef to enforce a consistent access mask size and uniformly use a 16-bits type. This will helps transition to a 32-bits value one day. Add a build check to make sure all (filesystem) access rights fit in. This will be extended with a following commit. Reviewed-by: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/r/20220506161102.525323-2-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Format with clang-formatMickaël Salaün2022-05-091-38/+40
| | | | | | | | | | | | | | | Let's follow a consistent and documented coding style. Everything may not be to our liking but it is better than tacit knowledge. Moreover, this will help maintain style consistency between different developers. This contains only whitespace changes. Automatically formatted with: clang-format-14 -i security/landlock/*.[ch] include/uapi/linux/landlock.h Link: https://lore.kernel.org/r/20220506160513.523257-3-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Add clang-format exceptionsMickaël Salaün2022-05-091-0/+2
| | | | | | | | | | | In preparation to a following commit, add clang-format on and clang-format off stanzas around constant definitions. This enables to keep aligned values, which is much more readable than packed definitions. Link: https://lore.kernel.org/r/20220506160513.523257-2-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
* landlock: Support filesystem access-controlMickaël Salaün2021-04-221-0/+692
Using Landlock objects and ruleset, it is possible to tag inodes according to a process's domain. To enable an unprivileged process to express a file hierarchy, it first needs to open a directory (or a file) and pass this file descriptor to the kernel through landlock_add_rule(2). When checking if a file access request is allowed, we walk from the requested dentry to the real root, following the different mount layers. The access to each "tagged" inodes are collected according to their rule layer level, and ANDed to create access to the requested file hierarchy. This makes possible to identify a lot of files without tagging every inodes nor modifying the filesystem, while still following the view and understanding the user has from the filesystem. Add a new ARCH_EPHEMERAL_INODES for UML because it currently does not keep the same struct inodes for the same inodes whereas these inodes are in use. This commit adds a minimal set of supported filesystem access-control which doesn't enable to restrict all file-related actions. This is the result of multiple discussions to minimize the code of Landlock to ease review. Thanks to the Landlock design, extending this access-control without breaking user space will not be a problem. Moreover, seccomp filters can be used to restrict the use of syscall families which may not be currently handled by Landlock. Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: James Morris <jmorris@namei.org> Cc: Jann Horn <jannh@google.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Kees Cook <keescook@chromium.org> Cc: Richard Weinberger <richard@nod.at> Cc: Serge E. Hallyn <serge@hallyn.com> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> Link: https://lore.kernel.org/r/20210422154123.13086-8-mic@digikod.net Signed-off-by: James Morris <jamorris@linux.microsoft.com>
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