Merge tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull Landlock LSM from James Morris:
 "Add Landlock, a new LSM from Mickaël Salaün.

  Briefly, Landlock provides for unprivileged application sandboxing.

  From Mickaël's cover letter:
    "The goal of Landlock is to enable to restrict ambient rights (e.g.
     global filesystem access) for a set of processes. Because Landlock
     is a stackable LSM [1], it makes possible to create safe security
     sandboxes as new security layers in addition to the existing
     system-wide access-controls. This kind of sandbox is expected to
     help mitigate the security impact of bugs or unexpected/malicious
     behaviors in user-space applications. Landlock empowers any
     process, including unprivileged ones, to securely restrict
     themselves.

     Landlock is inspired by seccomp-bpf but instead of filtering
     syscalls and their raw arguments, a Landlock rule can restrict the
     use of kernel objects like file hierarchies, according to the
     kernel semantic. Landlock also takes inspiration from other OS
     sandbox mechanisms: XNU Sandbox, FreeBSD Capsicum or OpenBSD
     Pledge/Unveil.

     In this current form, Landlock misses some access-control features.
     This enables to minimize this patch series and ease review. This
     series still addresses multiple use cases, especially with the
     combined use of seccomp-bpf: applications with built-in sandboxing,
     init systems, security sandbox tools and security-oriented APIs [2]"

  The cover letter and v34 posting is here:

      https://lore.kernel.org/linux-security-module/20210422154123.13086-1-mic@digikod.net/

  See also:

      https://landlock.io/

  This code has had extensive design discussion and review over several
  years"

Link: https://lore.kernel.org/lkml/50db058a-7dde-441b-a7f9-f6837fe8b69f@schaufler-ca.com/ [1]
Link: https://lore.kernel.org/lkml/f646e1c7-33cf-333f-070c-0a40ad0468cd@digikod.net/ [2]

* tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  landlock: Enable user space to infer supported features
  landlock: Add user and kernel documentation
  samples/landlock: Add a sandbox manager example
  selftests/landlock: Add user space tests
  landlock: Add syscall implementations
  arch: Wire up Landlock syscalls
  fs,security: Add sb_delete hook
  landlock: Support filesystem access-control
  LSM: Infrastructure management of the superblock
  landlock: Add ptrace restrictions
  landlock: Set up the security framework and manage credentials
  landlock: Add ruleset and domain management
  landlock: Add object management

6 files changed, 161 insertions, 1 deletions

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 61f04f7dc1a4..04c01794de83 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -59,6 +59,7 @@ LSM_HOOK(int, 0, fs_context_dup, struct fs_context *fc,
 LSM_HOOK(int, -ENOPARAM, fs_context_parse_param, struct fs_context *fc,
 	 struct fs_parameter *param)
 LSM_HOOK(int, 0, sb_alloc_security, struct super_block *sb)
+LSM_HOOK(void, LSM_RET_VOID, sb_delete, struct super_block *sb)
 LSM_HOOK(void, LSM_RET_VOID, sb_free_security, struct super_block *sb)
 LSM_HOOK(void, LSM_RET_VOID, sb_free_mnt_opts, void *mnt_opts)
 LSM_HOOK(int, 0, sb_eat_lsm_opts, char *orig, void **mnt_opts)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index ba2ccd950833..5c4c5c0602cb 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -108,6 +108,9 @@
  *	allocated.
  *	@sb contains the super_block structure to be modified.
  *	Return 0 if operation was successful.
+ * @sb_delete:
+ *	Release objects tied to a superblock (e.g. inodes).
+ *	@sb contains the super_block structure being released.
  * @sb_free_security:
  *	Deallocate and clear the sb->s_security field.
  *	@sb contains the super_block structure to be modified.
@@ -1585,6 +1588,7 @@ struct lsm_blob_sizes {
 	int	lbs_cred;
 	int	lbs_file;
 	int	lbs_inode;
+	int	lbs_superblock;
 	int	lbs_ipc;
 	int	lbs_msg_msg;
 	int	lbs_task;
diff --git a/include/linux/security.h b/include/linux/security.h
index 9aeda3f9e838..06f7c50ce77f 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -291,6 +291,7 @@ void security_bprm_committed_creds(struct linux_binprm *bprm);
 int security_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc);
 int security_fs_context_parse_param(struct fs_context *fc, struct fs_parameter *param);
 int security_sb_alloc(struct super_block *sb);
+void security_sb_delete(struct super_block *sb);
 void security_sb_free(struct super_block *sb);
 void security_free_mnt_opts(void **mnt_opts);
 int security_sb_eat_lsm_opts(char *options, void **mnt_opts);
@@ -633,6 +634,9 @@ static inline int security_sb_alloc(struct super_block *sb)
 	return 0;
 }
 
+static inline void security_sb_delete(struct super_block *sb)
+{ }
+
 static inline void security_sb_free(struct super_block *sb)
 { }
 
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index a672bbe28577..050511e8f1f8 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -69,6 +69,8 @@ struct io_uring_params;
 struct clone_args;
 struct open_how;
 struct mount_attr;
+struct landlock_ruleset_attr;
+enum landlock_rule_type;
 
 #include <linux/types.h>
 #include <linux/aio_abi.h>
@@ -1043,6 +1045,11 @@ asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
 				       siginfo_t __user *info,
 				       unsigned int flags);
 asmlinkage long sys_pidfd_getfd(int pidfd, int fd, unsigned int flags);
+asmlinkage long sys_landlock_create_ruleset(const struct landlock_ruleset_attr __user *attr,
+		size_t size, __u32 flags);
+asmlinkage long sys_landlock_add_rule(int ruleset_fd, enum landlock_rule_type rule_type,
+		const void __user *rule_attr, __u32 flags);
+asmlinkage long sys_landlock_restrict_self(int ruleset_fd, __u32 flags);
 
 /*
  * Architecture-specific system calls
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 739c839d28fe..6de5a7fc066b 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -866,8 +866,15 @@ __SYSCALL(__NR_mount_setattr, sys_mount_setattr)
 #define __NR_quotactl_path 443
 __SYSCALL(__NR_quotactl_path, sys_quotactl_path)
 
+#define __NR_landlock_create_ruleset 444
+__SYSCALL(__NR_landlock_create_ruleset, sys_landlock_create_ruleset)
+#define __NR_landlock_add_rule 445
+__SYSCALL(__NR_landlock_add_rule, sys_landlock_add_rule)
+#define __NR_landlock_restrict_self 446
+__SYSCALL(__NR_landlock_restrict_self, sys_landlock_restrict_self)
+
 #undef __NR_syscalls
-#define __NR_syscalls 444
+#define __NR_syscalls 447
 
 /*
  * 32 bit systems traditionally used different
diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
new file mode 100644
index 000000000000..b3d952067f59
--- /dev/null
+++ b/include/uapi/linux/landlock.h
@@ -0,0 +1,137 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Landlock - User space API
+ *
+ * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2020 ANSSI
+ */
+
+#ifndef _UAPI_LINUX_LANDLOCK_H
+#define _UAPI_LINUX_LANDLOCK_H
+
+#include <linux/types.h>
+
+/**
+ * struct landlock_ruleset_attr - Ruleset definition
+ *
+ * Argument of sys_landlock_create_ruleset().  This structure can grow in
+ * future versions.
+ */
+struct landlock_ruleset_attr {
+	/**
+	 * @handled_access_fs: Bitmask of actions (cf. `Filesystem flags`_)
+	 * that is handled by this ruleset and should then be forbidden if no
+	 * rule explicitly allow them.  This is needed for backward
+	 * compatibility reasons.
+	 */
+	__u64 handled_access_fs;
+};
+
+/*
+ * sys_landlock_create_ruleset() flags:
+ *
+ * - %LANDLOCK_CREATE_RULESET_VERSION: Get the highest supported Landlock ABI
+ *   version.
+ */
+#define LANDLOCK_CREATE_RULESET_VERSION			(1U << 0)
+
+/**
+ * enum landlock_rule_type - Landlock rule type
+ *
+ * Argument of sys_landlock_add_rule().
+ */
+enum landlock_rule_type {
+	/**
+	 * @LANDLOCK_RULE_PATH_BENEATH: Type of a &struct
+	 * landlock_path_beneath_attr .
+	 */
+	LANDLOCK_RULE_PATH_BENEATH = 1,
+};
+
+/**
+ * struct landlock_path_beneath_attr - Path hierarchy definition
+ *
+ * Argument of sys_landlock_add_rule().
+ */
+struct landlock_path_beneath_attr {
+	/**
+	 * @allowed_access: Bitmask of allowed actions for this file hierarchy
+	 * (cf. `Filesystem flags`_).
+	 */
+	__u64 allowed_access;
+	/**
+	 * @parent_fd: File descriptor, open with ``O_PATH``, which identifies
+	 * the parent directory of a file hierarchy, or just a file.
+	 */
+	__s32 parent_fd;
+	/*
+	 * This struct is packed to avoid trailing reserved members.
+	 * Cf. security/landlock/syscalls.c:build_check_abi()
+	 */
+} __attribute__((packed));
+
+/**
+ * DOC: fs_access
+ *
+ * A set of actions on kernel objects may be defined by an attribute (e.g.
+ * &struct landlock_path_beneath_attr) including a bitmask of access.
+ *
+ * Filesystem flags
+ * ~~~~~~~~~~~~~~~~
+ *
+ * These flags enable to restrict a sandboxed process to a set of actions on
+ * files and directories.  Files or directories opened before the sandboxing
+ * are not subject to these restrictions.
+ *
+ * A file can only receive these access rights:
+ *
+ * - %LANDLOCK_ACCESS_FS_EXECUTE: Execute a file.
+ * - %LANDLOCK_ACCESS_FS_WRITE_FILE: Open a file with write access.
+ * - %LANDLOCK_ACCESS_FS_READ_FILE: Open a file with read access.
+ *
+ * A directory can receive access rights related to files or directories.  The
+ * following access right is applied to the directory itself, and the
+ * directories beneath it:
+ *
+ * - %LANDLOCK_ACCESS_FS_READ_DIR: Open a directory or list its content.
+ *
+ * However, the following access rights only apply to the content of a
+ * directory, not the directory itself:
+ *
+ * - %LANDLOCK_ACCESS_FS_REMOVE_DIR: Remove an empty directory or rename one.
+ * - %LANDLOCK_ACCESS_FS_REMOVE_FILE: Unlink (or rename) a file.
+ * - %LANDLOCK_ACCESS_FS_MAKE_CHAR: Create (or rename or link) a character
+ *   device.
+ * - %LANDLOCK_ACCESS_FS_MAKE_DIR: Create (or rename) a directory.
+ * - %LANDLOCK_ACCESS_FS_MAKE_REG: Create (or rename or link) a regular file.
+ * - %LANDLOCK_ACCESS_FS_MAKE_SOCK: Create (or rename or link) a UNIX domain
+ *   socket.
+ * - %LANDLOCK_ACCESS_FS_MAKE_FIFO: Create (or rename or link) a named pipe.
+ * - %LANDLOCK_ACCESS_FS_MAKE_BLOCK: Create (or rename or link) a block device.
+ * - %LANDLOCK_ACCESS_FS_MAKE_SYM: Create (or rename or link) a symbolic link.
+ *
+ * .. warning::
+ *
+ *   It is currently not possible to restrict some file-related actions
+ *   accessible through these syscall families: :manpage:`chdir(2)`,
+ *   :manpage:`truncate(2)`, :manpage:`stat(2)`, :manpage:`flock(2)`,
+ *   :manpage:`chmod(2)`, :manpage:`chown(2)`, :manpage:`setxattr(2)`,
+ *   :manpage:`utime(2)`, :manpage:`ioctl(2)`, :manpage:`fcntl(2)`,
+ *   :manpage:`access(2)`.
+ *   Future Landlock evolutions will enable to restrict them.
+ */
+#define LANDLOCK_ACCESS_FS_EXECUTE			(1ULL << 0)
+#define LANDLOCK_ACCESS_FS_WRITE_FILE			(1ULL << 1)
+#define LANDLOCK_ACCESS_FS_READ_FILE			(1ULL << 2)
+#define LANDLOCK_ACCESS_FS_READ_DIR			(1ULL << 3)
+#define LANDLOCK_ACCESS_FS_REMOVE_DIR			(1ULL << 4)
+#define LANDLOCK_ACCESS_FS_REMOVE_FILE			(1ULL << 5)
+#define LANDLOCK_ACCESS_FS_MAKE_CHAR			(1ULL << 6)
+#define LANDLOCK_ACCESS_FS_MAKE_DIR			(1ULL << 7)
+#define LANDLOCK_ACCESS_FS_MAKE_REG			(1ULL << 8)
+#define LANDLOCK_ACCESS_FS_MAKE_SOCK			(1ULL << 9)
+#define LANDLOCK_ACCESS_FS_MAKE_FIFO			(1ULL << 10)
+#define LANDLOCK_ACCESS_FS_MAKE_BLOCK			(1ULL << 11)
+#define LANDLOCK_ACCESS_FS_MAKE_SYM			(1ULL << 12)
+
+#endif /* _UAPI_LINUX_LANDLOCK_H */