linux/security/tomoyo/tomoyo.c
Mickaël Salaün 100f59d964
LSM: Remove double path_rename hook calls for RENAME_EXCHANGE
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
2022-05-23 13:27:58 +02:00

602 lines
16 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* security/tomoyo/tomoyo.c
*
* Copyright (C) 2005-2011 NTT DATA CORPORATION
*/
#include <linux/lsm_hooks.h>
#include "common.h"
/**
* tomoyo_domain - Get "struct tomoyo_domain_info" for current thread.
*
* Returns pointer to "struct tomoyo_domain_info" for current thread.
*/
struct tomoyo_domain_info *tomoyo_domain(void)
{
struct tomoyo_task *s = tomoyo_task(current);
if (s->old_domain_info && !current->in_execve) {
atomic_dec(&s->old_domain_info->users);
s->old_domain_info = NULL;
}
return s->domain_info;
}
/**
* tomoyo_cred_prepare - Target for security_prepare_creds().
*
* @new: Pointer to "struct cred".
* @old: Pointer to "struct cred".
* @gfp: Memory allocation flags.
*
* Returns 0.
*/
static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
gfp_t gfp)
{
/* Restore old_domain_info saved by previous execve() request. */
struct tomoyo_task *s = tomoyo_task(current);
if (s->old_domain_info && !current->in_execve) {
atomic_dec(&s->domain_info->users);
s->domain_info = s->old_domain_info;
s->old_domain_info = NULL;
}
return 0;
}
/**
* tomoyo_bprm_committed_creds - Target for security_bprm_committed_creds().
*
* @bprm: Pointer to "struct linux_binprm".
*/
static void tomoyo_bprm_committed_creds(struct linux_binprm *bprm)
{
/* Clear old_domain_info saved by execve() request. */
struct tomoyo_task *s = tomoyo_task(current);
atomic_dec(&s->old_domain_info->users);
s->old_domain_info = NULL;
}
#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
/**
* tomoyo_bprm_creds_for_exec - Target for security_bprm_creds_for_exec().
*
* @bprm: Pointer to "struct linux_binprm".
*
* Returns 0.
*/
static int tomoyo_bprm_creds_for_exec(struct linux_binprm *bprm)
{
/*
* Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
* for the first time.
*/
if (!tomoyo_policy_loaded)
tomoyo_load_policy(bprm->filename);
return 0;
}
#endif
/**
* tomoyo_bprm_check_security - Target for security_bprm_check().
*
* @bprm: Pointer to "struct linux_binprm".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
{
struct tomoyo_task *s = tomoyo_task(current);
/*
* Execute permission is checked against pathname passed to execve()
* using current domain.
*/
if (!s->old_domain_info) {
const int idx = tomoyo_read_lock();
const int err = tomoyo_find_next_domain(bprm);
tomoyo_read_unlock(idx);
return err;
}
/*
* Read permission is checked against interpreters using next domain.
*/
return tomoyo_check_open_permission(s->domain_info,
&bprm->file->f_path, O_RDONLY);
}
/**
* tomoyo_inode_getattr - Target for security_inode_getattr().
*
* @path: Pointer to "struct path".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_inode_getattr(const struct path *path)
{
return tomoyo_path_perm(TOMOYO_TYPE_GETATTR, path, NULL);
}
/**
* tomoyo_path_truncate - Target for security_path_truncate().
*
* @path: Pointer to "struct path".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_truncate(const struct path *path)
{
return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path, NULL);
}
/**
* tomoyo_path_unlink - Target for security_path_unlink().
*
* @parent: Pointer to "struct path".
* @dentry: Pointer to "struct dentry".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_unlink(const struct path *parent, struct dentry *dentry)
{
struct path path = { .mnt = parent->mnt, .dentry = dentry };
return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path, NULL);
}
/**
* tomoyo_path_mkdir - Target for security_path_mkdir().
*
* @parent: Pointer to "struct path".
* @dentry: Pointer to "struct dentry".
* @mode: DAC permission mode.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_mkdir(const struct path *parent, struct dentry *dentry,
umode_t mode)
{
struct path path = { .mnt = parent->mnt, .dentry = dentry };
return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
mode & S_IALLUGO);
}
/**
* tomoyo_path_rmdir - Target for security_path_rmdir().
*
* @parent: Pointer to "struct path".
* @dentry: Pointer to "struct dentry".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_rmdir(const struct path *parent, struct dentry *dentry)
{
struct path path = { .mnt = parent->mnt, .dentry = dentry };
return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path, NULL);
}
/**
* tomoyo_path_symlink - Target for security_path_symlink().
*
* @parent: Pointer to "struct path".
* @dentry: Pointer to "struct dentry".
* @old_name: Symlink's content.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_symlink(const struct path *parent, struct dentry *dentry,
const char *old_name)
{
struct path path = { .mnt = parent->mnt, .dentry = dentry };
return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path, old_name);
}
/**
* tomoyo_path_mknod - Target for security_path_mknod().
*
* @parent: Pointer to "struct path".
* @dentry: Pointer to "struct dentry".
* @mode: DAC permission mode.
* @dev: Device attributes.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_mknod(const struct path *parent, struct dentry *dentry,
umode_t mode, unsigned int dev)
{
struct path path = { .mnt = parent->mnt, .dentry = dentry };
int type = TOMOYO_TYPE_CREATE;
const unsigned int perm = mode & S_IALLUGO;
switch (mode & S_IFMT) {
case S_IFCHR:
type = TOMOYO_TYPE_MKCHAR;
break;
case S_IFBLK:
type = TOMOYO_TYPE_MKBLOCK;
break;
default:
goto no_dev;
}
return tomoyo_mkdev_perm(type, &path, perm, dev);
no_dev:
switch (mode & S_IFMT) {
case S_IFIFO:
type = TOMOYO_TYPE_MKFIFO;
break;
case S_IFSOCK:
type = TOMOYO_TYPE_MKSOCK;
break;
}
return tomoyo_path_number_perm(type, &path, perm);
}
/**
* tomoyo_path_link - Target for security_path_link().
*
* @old_dentry: Pointer to "struct dentry".
* @new_dir: Pointer to "struct path".
* @new_dentry: Pointer to "struct dentry".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_link(struct dentry *old_dentry, const struct path *new_dir,
struct dentry *new_dentry)
{
struct path path1 = { .mnt = new_dir->mnt, .dentry = old_dentry };
struct path path2 = { .mnt = new_dir->mnt, .dentry = new_dentry };
return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
}
/**
* tomoyo_path_rename - Target for security_path_rename().
*
* @old_parent: Pointer to "struct path".
* @old_dentry: Pointer to "struct dentry".
* @new_parent: Pointer to "struct path".
* @new_dentry: Pointer to "struct dentry".
* @flags: Rename options.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_rename(const struct path *old_parent,
struct dentry *old_dentry,
const struct path *new_parent,
struct dentry *new_dentry,
const unsigned int flags)
{
struct path path1 = { .mnt = old_parent->mnt, .dentry = old_dentry };
struct path path2 = { .mnt = new_parent->mnt, .dentry = new_dentry };
if (flags & RENAME_EXCHANGE) {
const int err = tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path2,
&path1);
if (err)
return err;
}
return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
}
/**
* tomoyo_file_fcntl - Target for security_file_fcntl().
*
* @file: Pointer to "struct file".
* @cmd: Command for fcntl().
* @arg: Argument for @cmd.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
unsigned long arg)
{
if (!(cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND)))
return 0;
return tomoyo_check_open_permission(tomoyo_domain(), &file->f_path,
O_WRONLY | (arg & O_APPEND));
}
/**
* tomoyo_file_open - Target for security_file_open().
*
* @f: Pointer to "struct file".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_file_open(struct file *f)
{
/* Don't check read permission here if called from execve(). */
if (current->in_execve)
return 0;
return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path,
f->f_flags);
}
/**
* tomoyo_file_ioctl - Target for security_file_ioctl().
*
* @file: Pointer to "struct file".
* @cmd: Command for ioctl().
* @arg: Argument for @cmd.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
}
/**
* tomoyo_path_chmod - Target for security_path_chmod().
*
* @path: Pointer to "struct path".
* @mode: DAC permission mode.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_chmod(const struct path *path, umode_t mode)
{
return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, path,
mode & S_IALLUGO);
}
/**
* tomoyo_path_chown - Target for security_path_chown().
*
* @path: Pointer to "struct path".
* @uid: Owner ID.
* @gid: Group ID.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_chown(const struct path *path, kuid_t uid, kgid_t gid)
{
int error = 0;
if (uid_valid(uid))
error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path,
from_kuid(&init_user_ns, uid));
if (!error && gid_valid(gid))
error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path,
from_kgid(&init_user_ns, gid));
return error;
}
/**
* tomoyo_path_chroot - Target for security_path_chroot().
*
* @path: Pointer to "struct path".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_chroot(const struct path *path)
{
return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path, NULL);
}
/**
* tomoyo_sb_mount - Target for security_sb_mount().
*
* @dev_name: Name of device file. Maybe NULL.
* @path: Pointer to "struct path".
* @type: Name of filesystem type. Maybe NULL.
* @flags: Mount options.
* @data: Optional data. Maybe NULL.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_sb_mount(const char *dev_name, const struct path *path,
const char *type, unsigned long flags, void *data)
{
return tomoyo_mount_permission(dev_name, path, type, flags, data);
}
/**
* tomoyo_sb_umount - Target for security_sb_umount().
*
* @mnt: Pointer to "struct vfsmount".
* @flags: Unmount options.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
{
struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path, NULL);
}
/**
* tomoyo_sb_pivotroot - Target for security_sb_pivotroot().
*
* @old_path: Pointer to "struct path".
* @new_path: Pointer to "struct path".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_sb_pivotroot(const struct path *old_path, const struct path *new_path)
{
return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
}
/**
* tomoyo_socket_listen - Check permission for listen().
*
* @sock: Pointer to "struct socket".
* @backlog: Backlog parameter.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_socket_listen(struct socket *sock, int backlog)
{
return tomoyo_socket_listen_permission(sock);
}
/**
* tomoyo_socket_connect - Check permission for connect().
*
* @sock: Pointer to "struct socket".
* @addr: Pointer to "struct sockaddr".
* @addr_len: Size of @addr.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_socket_connect(struct socket *sock, struct sockaddr *addr,
int addr_len)
{
return tomoyo_socket_connect_permission(sock, addr, addr_len);
}
/**
* tomoyo_socket_bind - Check permission for bind().
*
* @sock: Pointer to "struct socket".
* @addr: Pointer to "struct sockaddr".
* @addr_len: Size of @addr.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_socket_bind(struct socket *sock, struct sockaddr *addr,
int addr_len)
{
return tomoyo_socket_bind_permission(sock, addr, addr_len);
}
/**
* tomoyo_socket_sendmsg - Check permission for sendmsg().
*
* @sock: Pointer to "struct socket".
* @msg: Pointer to "struct msghdr".
* @size: Size of message.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_socket_sendmsg(struct socket *sock, struct msghdr *msg,
int size)
{
return tomoyo_socket_sendmsg_permission(sock, msg, size);
}
struct lsm_blob_sizes tomoyo_blob_sizes __lsm_ro_after_init = {
.lbs_task = sizeof(struct tomoyo_task),
};
/**
* tomoyo_task_alloc - Target for security_task_alloc().
*
* @task: Pointer to "struct task_struct".
* @clone_flags: clone() flags.
*
* Returns 0.
*/
static int tomoyo_task_alloc(struct task_struct *task,
unsigned long clone_flags)
{
struct tomoyo_task *old = tomoyo_task(current);
struct tomoyo_task *new = tomoyo_task(task);
new->domain_info = old->domain_info;
atomic_inc(&new->domain_info->users);
new->old_domain_info = NULL;
return 0;
}
/**
* tomoyo_task_free - Target for security_task_free().
*
* @task: Pointer to "struct task_struct".
*/
static void tomoyo_task_free(struct task_struct *task)
{
struct tomoyo_task *s = tomoyo_task(task);
if (s->domain_info) {
atomic_dec(&s->domain_info->users);
s->domain_info = NULL;
}
if (s->old_domain_info) {
atomic_dec(&s->old_domain_info->users);
s->old_domain_info = NULL;
}
}
/*
* tomoyo_security_ops is a "struct security_operations" which is used for
* registering TOMOYO.
*/
static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(cred_prepare, tomoyo_cred_prepare),
LSM_HOOK_INIT(bprm_committed_creds, tomoyo_bprm_committed_creds),
LSM_HOOK_INIT(task_alloc, tomoyo_task_alloc),
LSM_HOOK_INIT(task_free, tomoyo_task_free),
#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
LSM_HOOK_INIT(bprm_creds_for_exec, tomoyo_bprm_creds_for_exec),
#endif
LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security),
LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl),
LSM_HOOK_INIT(file_open, tomoyo_file_open),
LSM_HOOK_INIT(path_truncate, tomoyo_path_truncate),
LSM_HOOK_INIT(path_unlink, tomoyo_path_unlink),
LSM_HOOK_INIT(path_mkdir, tomoyo_path_mkdir),
LSM_HOOK_INIT(path_rmdir, tomoyo_path_rmdir),
LSM_HOOK_INIT(path_symlink, tomoyo_path_symlink),
LSM_HOOK_INIT(path_mknod, tomoyo_path_mknod),
LSM_HOOK_INIT(path_link, tomoyo_path_link),
LSM_HOOK_INIT(path_rename, tomoyo_path_rename),
LSM_HOOK_INIT(inode_getattr, tomoyo_inode_getattr),
LSM_HOOK_INIT(file_ioctl, tomoyo_file_ioctl),
LSM_HOOK_INIT(path_chmod, tomoyo_path_chmod),
LSM_HOOK_INIT(path_chown, tomoyo_path_chown),
LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot),
LSM_HOOK_INIT(sb_mount, tomoyo_sb_mount),
LSM_HOOK_INIT(sb_umount, tomoyo_sb_umount),
LSM_HOOK_INIT(sb_pivotroot, tomoyo_sb_pivotroot),
LSM_HOOK_INIT(socket_bind, tomoyo_socket_bind),
LSM_HOOK_INIT(socket_connect, tomoyo_socket_connect),
LSM_HOOK_INIT(socket_listen, tomoyo_socket_listen),
LSM_HOOK_INIT(socket_sendmsg, tomoyo_socket_sendmsg),
};
/* Lock for GC. */
DEFINE_SRCU(tomoyo_ss);
int tomoyo_enabled __lsm_ro_after_init = 1;
/**
* tomoyo_init - Register TOMOYO Linux as a LSM module.
*
* Returns 0.
*/
static int __init tomoyo_init(void)
{
struct tomoyo_task *s = tomoyo_task(current);
/* register ourselves with the security framework */
security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
pr_info("TOMOYO Linux initialized\n");
s->domain_info = &tomoyo_kernel_domain;
atomic_inc(&tomoyo_kernel_domain.users);
s->old_domain_info = NULL;
tomoyo_mm_init();
return 0;
}
DEFINE_LSM(tomoyo) = {
.name = "tomoyo",
.enabled = &tomoyo_enabled,
.flags = LSM_FLAG_LEGACY_MAJOR,
.blobs = &tomoyo_blob_sizes,
.init = tomoyo_init,
};