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linux/security/landlock/limits.h

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landlock: Add ruleset and domain management A Landlock ruleset is mainly a red-black tree with Landlock rules as nodes. This enables quick update and lookup to match a requested access, e.g. to a file. A ruleset is usable through a dedicated file descriptor (cf. following commit implementing syscalls) which enables a process to create and populate a ruleset with new rules. A domain is a ruleset tied to a set of processes. This group of rules defines the security policy enforced on these processes and their future children. A domain can transition to a new domain which is the intersection of all its constraints and those of a ruleset provided by the current process. This modification only impact the current process. This means that a process can only gain more constraints (i.e. lose accesses) over time. Cc: James Morris <jmorris@namei.org> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> Acked-by: Serge Hallyn <serge@hallyn.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/r/20210422154123.13086-3-mic@digikod.net Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 15:41:12 +00:00
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Landlock LSM - Limits for different components
*
* Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
* Copyright © 2018-2020 ANSSI
*/
#ifndef _SECURITY_LANDLOCK_LIMITS_H
#define _SECURITY_LANDLOCK_LIMITS_H
landlock: Define access_mask_t to enforce a consistent access mask size 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>
2022-05-06 16:10:51 +00:00
#include <linux/bitops.h>
landlock: Add ruleset and domain management A Landlock ruleset is mainly a red-black tree with Landlock rules as nodes. This enables quick update and lookup to match a requested access, e.g. to a file. A ruleset is usable through a dedicated file descriptor (cf. following commit implementing syscalls) which enables a process to create and populate a ruleset with new rules. A domain is a ruleset tied to a set of processes. This group of rules defines the security policy enforced on these processes and their future children. A domain can transition to a new domain which is the intersection of all its constraints and those of a ruleset provided by the current process. This modification only impact the current process. This means that a process can only gain more constraints (i.e. lose accesses) over time. Cc: James Morris <jmorris@namei.org> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> Acked-by: Serge Hallyn <serge@hallyn.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/r/20210422154123.13086-3-mic@digikod.net Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 15:41:12 +00:00
#include <linux/limits.h>
landlock: Support filesystem access-control 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>
2021-04-22 15:41:17 +00:00
#include <uapi/linux/landlock.h>
landlock: Add ruleset and domain management A Landlock ruleset is mainly a red-black tree with Landlock rules as nodes. This enables quick update and lookup to match a requested access, e.g. to a file. A ruleset is usable through a dedicated file descriptor (cf. following commit implementing syscalls) which enables a process to create and populate a ruleset with new rules. A domain is a ruleset tied to a set of processes. This group of rules defines the security policy enforced on these processes and their future children. A domain can transition to a new domain which is the intersection of all its constraints and those of a ruleset provided by the current process. This modification only impact the current process. This means that a process can only gain more constraints (i.e. lose accesses) over time. Cc: James Morris <jmorris@namei.org> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> Acked-by: Serge Hallyn <serge@hallyn.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/r/20210422154123.13086-3-mic@digikod.net Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 15:41:12 +00:00
landlock: Add clang-format exceptions 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>
2022-05-06 16:05:07 +00:00
/* clang-format off */
landlock: Reduce the maximum number of layers to 16 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>
2022-05-06 16:10:52 +00:00
#define LANDLOCK_MAX_NUM_LAYERS 16
landlock: Add ruleset and domain management A Landlock ruleset is mainly a red-black tree with Landlock rules as nodes. This enables quick update and lookup to match a requested access, e.g. to a file. A ruleset is usable through a dedicated file descriptor (cf. following commit implementing syscalls) which enables a process to create and populate a ruleset with new rules. A domain is a ruleset tied to a set of processes. This group of rules defines the security policy enforced on these processes and their future children. A domain can transition to a new domain which is the intersection of all its constraints and those of a ruleset provided by the current process. This modification only impact the current process. This means that a process can only gain more constraints (i.e. lose accesses) over time. Cc: James Morris <jmorris@namei.org> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> Acked-by: Serge Hallyn <serge@hallyn.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/r/20210422154123.13086-3-mic@digikod.net Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 15:41:12 +00:00
#define LANDLOCK_MAX_NUM_RULES U32_MAX
landlock: Add IOCTL access right for character and block devices Introduces the LANDLOCK_ACCESS_FS_IOCTL_DEV right and increments the Landlock ABI version to 5. This access right applies to device-custom IOCTL commands when they are invoked on block or character device files. Like the truncate right, this right is associated with a file descriptor at the time of open(2), and gets respected even when the file descriptor is used outside of the thread which it was originally opened in. Therefore, a newly enabled Landlock policy does not apply to file descriptors which are already open. If the LANDLOCK_ACCESS_FS_IOCTL_DEV right is handled, only a small number of safe IOCTL commands will be permitted on newly opened device files. These include FIOCLEX, FIONCLEX, FIONBIO and FIOASYNC, as well as other IOCTL commands for regular files which are implemented in fs/ioctl.c. Noteworthy scenarios which require special attention: TTY devices are often passed into a process from the parent process, and so a newly enabled Landlock policy does not retroactively apply to them automatically. In the past, TTY devices have often supported IOCTL commands like TIOCSTI and some TIOCLINUX subcommands, which were letting callers control the TTY input buffer (and simulate keypresses). This should be restricted to CAP_SYS_ADMIN programs on modern kernels though. Known limitations: The LANDLOCK_ACCESS_FS_IOCTL_DEV access right is a coarse-grained control over IOCTL commands. Landlock users may use path-based restrictions in combination with their knowledge about the file system layout to control what IOCTLs can be done. Cc: Paul Moore <paul@paul-moore.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20240419161122.2023765-2-gnoack@google.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-04-19 16:11:12 +00:00
#define LANDLOCK_LAST_ACCESS_FS LANDLOCK_ACCESS_FS_IOCTL_DEV
landlock: Support filesystem access-control 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>
2021-04-22 15:41:17 +00:00
#define LANDLOCK_MASK_ACCESS_FS ((LANDLOCK_LAST_ACCESS_FS << 1) - 1)
landlock: Define access_mask_t to enforce a consistent access mask size 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>
2022-05-06 16:10:51 +00:00
#define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS)
landlock: Support filesystem access-control 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>
2021-04-22 15:41:17 +00:00
landlock: Support network rules with TCP bind and connect Add network rules support in the ruleset management helpers and the landlock_create_ruleset() syscall. Extend user space API to support network actions: * Add new network access rights: LANDLOCK_ACCESS_NET_BIND_TCP and LANDLOCK_ACCESS_NET_CONNECT_TCP. * Add a new network rule type: LANDLOCK_RULE_NET_PORT tied to struct landlock_net_port_attr. The allowed_access field contains the network access rights, and the port field contains the port value according to the controlled protocol. This field can take up to a 64-bit value but the maximum value depends on the related protocol (e.g. 16-bit value for TCP). Network port is in host endianness [1]. * Add a new handled_access_net field to struct landlock_ruleset_attr that contains network access rights. * Increment the Landlock ABI version to 4. Implement socket_bind() and socket_connect() LSM hooks, which enable to control TCP socket binding and connection to specific ports. Expand access_masks_t from u16 to u32 to be able to store network access rights alongside filesystem access rights for rulesets' handled access rights. Access rights are not tied to socket file descriptors but checked at bind() or connect() call time against the caller's Landlock domain. For the filesystem, a file descriptor is a direct access to a file/data. However, for network sockets, we cannot identify for which data or peer a newly created socket will give access to. Indeed, we need to wait for a connect or bind request to identify the use case for this socket. Likewise a directory file descriptor may enable to open another file (i.e. a new data item), but this opening is also restricted by the caller's domain, not the file descriptor's access rights [2]. [1] https://lore.kernel.org/r/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net [2] https://lore.kernel.org/r/263c1eb3-602f-57fe-8450-3f138581bee7@digikod.net Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> Link: https://lore.kernel.org/r/20231026014751.414649-9-konstantin.meskhidze@huawei.com [mic: Extend commit message, fix typo in comments, and specify endianness in the documentation] Co-developed-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-10-26 01:47:47 +00:00
#define LANDLOCK_LAST_ACCESS_NET LANDLOCK_ACCESS_NET_CONNECT_TCP
#define LANDLOCK_MASK_ACCESS_NET ((LANDLOCK_LAST_ACCESS_NET << 1) - 1)
#define LANDLOCK_NUM_ACCESS_NET __const_hweight64(LANDLOCK_MASK_ACCESS_NET)
landlock: Add clang-format exceptions 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>
2022-05-06 16:05:07 +00:00
/* clang-format on */
landlock: Add ruleset and domain management A Landlock ruleset is mainly a red-black tree with Landlock rules as nodes. This enables quick update and lookup to match a requested access, e.g. to a file. A ruleset is usable through a dedicated file descriptor (cf. following commit implementing syscalls) which enables a process to create and populate a ruleset with new rules. A domain is a ruleset tied to a set of processes. This group of rules defines the security policy enforced on these processes and their future children. A domain can transition to a new domain which is the intersection of all its constraints and those of a ruleset provided by the current process. This modification only impact the current process. This means that a process can only gain more constraints (i.e. lose accesses) over time. Cc: James Morris <jmorris@namei.org> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> Acked-by: Serge Hallyn <serge@hallyn.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/r/20210422154123.13086-3-mic@digikod.net Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 15:41:12 +00:00
#endif /* _SECURITY_LANDLOCK_LIMITS_H */
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