[PATCH v1 3/3] landlock: Fix documentation style
Günther Noack
gnoack3000 at gmail.com
Fri Sep 23 21:18:21 UTC 2022
On Fri, Sep 23, 2022 at 05:42:07PM +0200, Mickaël Salaün wrote:
> It seems that all code should use double backquotes, which is also used
> to convert "%" defines. Let's use an homogeneous style and remove all
> use of simple backquotes (which should only be used for emphasis).
>
> Cc: Günther Noack <gnoack3000 at gmail.com>
> Cc: Paul Moore <paul at paul-moore.com>
> Signed-off-by: Mickaël Salaün <mic at digikod.net>
> Link: https://lore.kernel.org/r/20220923154207.3311629-4-mic@digikod.net
> ---
> Documentation/security/landlock.rst | 4 +--
> Documentation/userspace-api/landlock.rst | 25 ++++++++-------
> include/uapi/linux/landlock.h | 10 +++---
> security/landlock/syscalls.c | 40 ++++++++++++------------
> 4 files changed, 40 insertions(+), 39 deletions(-)
>
> diff --git a/Documentation/security/landlock.rst b/Documentation/security/landlock.rst
> index cc9617f3175b..c0029d5d02eb 100644
> --- a/Documentation/security/landlock.rst
> +++ b/Documentation/security/landlock.rst
> @@ -54,8 +54,8 @@ content of a listed inode. Indeed, a file name is local to its parent
> directory, and an inode can be referenced by multiple file names thanks to
> (hard) links. Being able to unlink a file only has a direct impact on the
> directory, not the unlinked inode. This is the reason why
> -`LANDLOCK_ACCESS_FS_REMOVE_FILE` or `LANDLOCK_ACCESS_FS_REFER` are not allowed
> -to be tied to files but only to directories.
> +``LANDLOCK_ACCESS_FS_REMOVE_FILE`` or ``LANDLOCK_ACCESS_FS_REFER`` are not
> +allowed to be tied to files but only to directories.
>
> Tests
> =====
> diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst
> index 83bae71bf042..cec780c2f497 100644
> --- a/Documentation/userspace-api/landlock.rst
> +++ b/Documentation/userspace-api/landlock.rst
> @@ -69,7 +69,7 @@ should try to protect users as much as possible whatever the kernel they are
> using. To avoid binary enforcement (i.e. either all security features or
> none), we can leverage a dedicated Landlock command to get the current version
> of the Landlock ABI and adapt the handled accesses. Let's check if we should
> -remove the `LANDLOCK_ACCESS_FS_REFER` access right which is only supported
> +remove the ``LANDLOCK_ACCESS_FS_REFER`` access right which is only supported
> starting with the second version of the ABI.
>
> .. code-block:: c
> @@ -128,7 +128,7 @@ descriptor.
> It may also be required to create rules following the same logic as explained
> for the ruleset creation, by filtering access rights according to the Landlock
> ABI version. In this example, this is not required because
> -`LANDLOCK_ACCESS_FS_REFER` is not allowed by any rule.
> +``LANDLOCK_ACCESS_FS_REFER`` is not allowed by any rule.
>
> We now have a ruleset with one rule allowing read access to ``/usr`` while
> denying all other handled accesses for the filesystem. The next step is to
> @@ -154,8 +154,8 @@ The current thread is now ready to sandbox itself with the ruleset.
> }
> close(ruleset_fd);
>
> -If the `landlock_restrict_self` system call succeeds, the current thread is now
> -restricted and this policy will be enforced on all its subsequently created
> +If the ``landlock_restrict_self`` system call succeeds, the current thread is
> +now restricted and this policy will be enforced on all its subsequently created
> children as well. Once a thread is landlocked, there is no way to remove its
> security policy; only adding more restrictions is allowed. These threads are
> now in a new Landlock domain, merge of their parent one (if any) with the new
> @@ -175,7 +175,8 @@ depend on their location (i.e. parent directories). This is particularly
> relevant when we want to allow linking or renaming. Indeed, having consistent
> access rights per directory enables to change the location of such directory
> without relying on the destination directory access rights (except those that
> -are required for this operation, see `LANDLOCK_ACCESS_FS_REFER` documentation).
> +are required for this operation, see ``LANDLOCK_ACCESS_FS_REFER``
> +documentation).
> Having self-sufficient hierarchies also helps to tighten the required access
> rights to the minimal set of data. This also helps avoid sinkhole directories,
> i.e. directories where data can be linked to but not linked from. However,
> @@ -259,7 +260,7 @@ Backward and forward compatibility
>
> Landlock is designed to be compatible with past and future versions of the
> kernel. This is achieved thanks to the system call attributes and the
> -associated bitflags, particularly the ruleset's `handled_access_fs`. Making
> +associated bitflags, particularly the ruleset's ``handled_access_fs``. Making
> handled access right explicit enables the kernel and user space to have a clear
> contract with each other. This is required to make sure sandboxing will not
> get stricter with a system update, which could break applications.
> @@ -394,7 +395,7 @@ according to the potentially lost constraints. To protect against privilege
> escalations through renaming or linking, and for the sake of simplicity,
> Landlock previously limited linking and renaming to the same directory.
> Starting with the Landlock ABI version 2, it is now possible to securely
> -control renaming and linking thanks to the new `LANDLOCK_ACCESS_FS_REFER`
> +control renaming and linking thanks to the new ``LANDLOCK_ACCESS_FS_REFER``
> access right.
>
> .. _kernel_support:
> @@ -403,14 +404,14 @@ Kernel support
> ==============
>
> Landlock was first introduced in Linux 5.13 but it must be configured at build
> -time with `CONFIG_SECURITY_LANDLOCK=y`. Landlock must also be enabled at boot
> +time with ``CONFIG_SECURITY_LANDLOCK=y``. Landlock must also be enabled at boot
> time as the other security modules. The list of security modules enabled by
> -default is set with `CONFIG_LSM`. The kernel configuration should then
> -contains `CONFIG_LSM=landlock,[...]` with `[...]` as the list of other
> +default is set with ``CONFIG_LSM``. The kernel configuration should then
> +contains ``CONFIG_LSM=landlock,[...]`` with ``[...]`` as the list of other
> potentially useful security modules for the running system (see the
> -`CONFIG_LSM` help).
> +``CONFIG_LSM`` help).
>
> -If the running kernel does not have `landlock` in `CONFIG_LSM`, then we can
> +If the running kernel does not have ``landlock`` in ``CONFIG_LSM``, then we can
> still enable it by adding ``lsm=landlock,[...]`` to
> Documentation/admin-guide/kernel-parameters.rst thanks to the bootloader
> configuration.
> diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
> index 23df4e0e8ace..9c4bcc37a455 100644
> --- a/include/uapi/linux/landlock.h
> +++ b/include/uapi/linux/landlock.h
> @@ -26,7 +26,7 @@ struct landlock_ruleset_attr {
> * Landlock filesystem access rights that are not part of
> * handled_access_fs are allowed. This is needed for backward
> * compatibility reasons. One exception is the
> - * LANDLOCK_ACCESS_FS_REFER access right, which is always implicitly
> + * %LANDLOCK_ACCESS_FS_REFER access right, which is always implicitly
At the risk of asking a newbie question, why is this access right
prefixed with % in this command, but most others are surrounded by
double-backticks in other places?
According to [1], % is used to denote a constant - should these
LANDLOCK_ACCESS_FS* rights not all be showing up as constants?
[1] https://docs.kernel.org/doc-guide/kernel-doc.html#highlights-and-cross-references
Apart from this item, this change looks good.
> * handled, but must still be explicitly handled to add new rules with
> * this access right.
> */
> @@ -128,11 +128,11 @@ struct landlock_path_beneath_attr {
> * hierarchy must also always have the same or a superset of restrictions of
> * the source hierarchy. If it is not the case, or if the domain doesn't
> * handle this access right, such actions are denied by default with errno
> - * set to EXDEV. Linking also requires a LANDLOCK_ACCESS_FS_MAKE_* access
> - * right on the destination directory, and renaming also requires a
> - * LANDLOCK_ACCESS_FS_REMOVE_* access right on the source's (file or
> + * set to ``EXDEV``. Linking also requires a ``LANDLOCK_ACCESS_FS_MAKE_*``
> + * access right on the destination directory, and renaming also requires a
> + * ``LANDLOCK_ACCESS_FS_REMOVE_*`` access right on the source's (file or
> * directory) parent. Otherwise, such actions are denied with errno set to
> - * EACCES. The EACCES errno prevails over EXDEV to let user space
> + * ``EACCES``. The ``EACCES`` errno prevails over ``EXDEV`` to let user space
> * efficiently deal with an unrecoverable error.
> *
> * .. warning::
> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
> index 735a0865ea11..2ca0ccbd905a 100644
> --- a/security/landlock/syscalls.c
> +++ b/security/landlock/syscalls.c
> @@ -149,10 +149,10 @@ static const struct file_operations ruleset_fops = {
> *
> * Possible returned errors are:
> *
> - * - EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
> - * - EINVAL: unknown @flags, or unknown access, or too small @size;
> - * - E2BIG or EFAULT: @attr or @size inconsistencies;
> - * - ENOMSG: empty &landlock_ruleset_attr.handled_access_fs.
> + * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
> + * - %EINVAL: unknown @flags, or unknown access, or too small @size;
> + * - %E2BIG or %EFAULT: @attr or @size inconsistencies;
> + * - %ENOMSG: empty &landlock_ruleset_attr.handled_access_fs.
> */
> SYSCALL_DEFINE3(landlock_create_ruleset,
> const struct landlock_ruleset_attr __user *const, attr,
> @@ -280,7 +280,7 @@ static int get_path_from_fd(const s32 fd, struct path *const path)
> * @ruleset_fd: File descriptor tied to the ruleset that should be extended
> * with the new rule.
> * @rule_type: Identify the structure type pointed to by @rule_attr (only
> - * LANDLOCK_RULE_PATH_BENEATH for now).
> + * %LANDLOCK_RULE_PATH_BENEATH for now).
> * @rule_attr: Pointer to a rule (only of type &struct
> * landlock_path_beneath_attr for now).
> * @flags: Must be 0.
> @@ -290,17 +290,17 @@ static int get_path_from_fd(const s32 fd, struct path *const path)
> *
> * Possible returned errors are:
> *
> - * - EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
> - * - EINVAL: @flags is not 0, or inconsistent access in the rule (i.e.
> + * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
> + * - %EINVAL: @flags is not 0, or inconsistent access in the rule (i.e.
> * &landlock_path_beneath_attr.allowed_access is not a subset of the
> * ruleset handled accesses);
> - * - ENOMSG: Empty accesses (e.g. &landlock_path_beneath_attr.allowed_access);
> - * - EBADF: @ruleset_fd is not a file descriptor for the current thread, or a
> + * - %ENOMSG: Empty accesses (e.g. &landlock_path_beneath_attr.allowed_access);
> + * - %EBADF: @ruleset_fd is not a file descriptor for the current thread, or a
> * member of @rule_attr is not a file descriptor as expected;
> - * - EBADFD: @ruleset_fd is not a ruleset file descriptor, or a member of
> + * - %EBADFD: @ruleset_fd is not a ruleset file descriptor, or a member of
> * @rule_attr is not the expected file descriptor type;
> - * - EPERM: @ruleset_fd has no write access to the underlying ruleset;
> - * - EFAULT: @rule_attr inconsistency.
> + * - %EPERM: @ruleset_fd has no write access to the underlying ruleset;
> + * - %EFAULT: @rule_attr inconsistency.
> */
> SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
> const enum landlock_rule_type, rule_type,
> @@ -378,20 +378,20 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
> * @flags: Must be 0.
> *
> * This system call enables to enforce a Landlock ruleset on the current
> - * thread. Enforcing a ruleset requires that the task has CAP_SYS_ADMIN in its
> + * thread. Enforcing a ruleset requires that the task has %CAP_SYS_ADMIN in its
> * namespace or is running with no_new_privs. This avoids scenarios where
> * unprivileged tasks can affect the behavior of privileged children.
> *
> * Possible returned errors are:
> *
> - * - EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
> - * - EINVAL: @flags is not 0.
> - * - EBADF: @ruleset_fd is not a file descriptor for the current thread;
> - * - EBADFD: @ruleset_fd is not a ruleset file descriptor;
> - * - EPERM: @ruleset_fd has no read access to the underlying ruleset, or the
> + * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
> + * - %EINVAL: @flags is not 0.
> + * - %EBADF: @ruleset_fd is not a file descriptor for the current thread;
> + * - %EBADFD: @ruleset_fd is not a ruleset file descriptor;
> + * - %EPERM: @ruleset_fd has no read access to the underlying ruleset, or the
> * current thread is not running with no_new_privs, or it doesn't have
> - * CAP_SYS_ADMIN in its namespace.
> - * - E2BIG: The maximum number of stacked rulesets is reached for the current
> + * %CAP_SYS_ADMIN in its namespace.
> + * - %E2BIG: The maximum number of stacked rulesets is reached for the current
> * thread.
> */
> SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
> --
> 2.37.2
>
--
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