Avoid beyond bounds copy while caching ACL

[zen-stable.git] / security / tomoyo / tomoyo.c

/*
 * security/tomoyo/tomoyo.c
 *
 * Copyright (C) 2005-2011  NTT DATA CORPORATION
 */

#include <linux/security.h>
#include "common.h"

/**
 * tomoyo_cred_alloc_blank - Target for security_cred_alloc_blank().
 *
 * @new: Pointer to "struct cred".
 * @gfp: Memory allocation flags.
 *
 * Returns 0.
 */
static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
{
        new->security = NULL;
        return 0;
}

/**
 * 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)
{
        struct tomoyo_domain_info *domain = old->security;
        new->security = domain;
        if (domain)
                atomic_inc(&domain->users);
        return 0;
}

/**
 * tomoyo_cred_transfer - Target for security_transfer_creds().
 *
 * @new: Pointer to "struct cred".
 * @old: Pointer to "struct cred".
 */
static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
{
        tomoyo_cred_prepare(new, old, 0);
}

/**
 * tomoyo_cred_free - Target for security_cred_free().
 *
 * @cred: Pointer to "struct cred".
 */
static void tomoyo_cred_free(struct cred *cred)
{
        struct tomoyo_domain_info *domain = cred->security;
        if (domain)
                atomic_dec(&domain->users);
}

/**
 * tomoyo_bprm_set_creds - Target for security_bprm_set_creds().
 *
 * @bprm: Pointer to "struct linux_binprm".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
{
        int rc;

        rc = cap_bprm_set_creds(bprm);
        if (rc)
                return rc;

        /*
         * Do only if this function is called for the first time of an execve
         * operation.
         */
        if (bprm->cred_prepared)
                return 0;
#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
        /*
         * 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);
#endif
        /*
         * Release reference to "struct tomoyo_domain_info" stored inside
         * "bprm->cred->security". New reference to "struct tomoyo_domain_info"
         * stored inside "bprm->cred->security" will be acquired later inside
         * tomoyo_find_next_domain().
         */
        atomic_dec(&((struct tomoyo_domain_info *)
                     bprm->cred->security)->users);
        /*
         * Tell tomoyo_bprm_check_security() is called for the first time of an
         * execve operation.
         */
        bprm->cred->security = NULL;
        return 0;
}

/**
 * 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_domain_info *domain = bprm->cred->security;

        /*
         * Execute permission is checked against pathname passed to do_execve()
         * using current domain.
         */
        if (!domain) {
                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(domain, &bprm->file->f_path,
                                            O_RDONLY);
}

/**
 * tomoyo_inode_getattr - Target for security_inode_getattr().
 *
 * @mnt:    Pointer to "struct vfsmount".
 * @dentry: Pointer to "struct dentry".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_inode_getattr(struct vfsmount *mnt, struct dentry *dentry)
{
        struct path path = { mnt, dentry };
        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(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(struct path *parent, struct dentry *dentry)
{
        struct path path = { parent->mnt, 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(struct path *parent, struct dentry *dentry,
                             umode_t mode)
{
        struct path path = { parent->mnt, 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(struct path *parent, struct dentry *dentry)
{
        struct path path = { parent->mnt, 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(struct path *parent, struct dentry *dentry,
                               const char *old_name)
{
        struct path path = { parent->mnt, 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(struct path *parent, struct dentry *dentry,
                             umode_t mode, unsigned int dev)
{
        struct path path = { parent->mnt, 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, struct path *new_dir,
                            struct dentry *new_dentry)
{
        struct path path1 = { new_dir->mnt, old_dentry };
        struct path path2 = { new_dir->mnt, 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".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_rename(struct path *old_parent,
                              struct dentry *old_dentry,
                              struct path *new_parent,
                              struct dentry *new_dentry)
{
        struct path path1 = { old_parent->mnt, old_dentry };
        struct path path2 = { new_parent->mnt, new_dentry };
        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_dentry_open - Target for security_dentry_open().
 *
 * @f:    Pointer to "struct file".
 * @cred: Pointer to "struct cred".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
{
        int flags = f->f_flags;
        /* Don't check read permission here if called from do_execve(). */
        if (current->in_execve)
                return 0;
        return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, 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(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(struct path *path, uid_t uid, gid_t gid)
{
        int error = 0;
        if (uid != (uid_t) -1)
                error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path, uid);
        if (!error && gid != (gid_t) -1)
                error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path, 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(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(char *dev_name, struct path *path,
                           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->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(struct path *old_path, 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);
}

/*
 * tomoyo_security_ops is a "struct security_operations" which is used for
 * registering TOMOYO.
 */
static struct security_operations tomoyo_security_ops = {
        .name                = "tomoyo",
        .cred_alloc_blank    = tomoyo_cred_alloc_blank,
        .cred_prepare        = tomoyo_cred_prepare,
        .cred_transfer       = tomoyo_cred_transfer,
        .cred_free           = tomoyo_cred_free,
        .bprm_set_creds      = tomoyo_bprm_set_creds,
        .bprm_check_security = tomoyo_bprm_check_security,
        .file_fcntl          = tomoyo_file_fcntl,
        .dentry_open         = tomoyo_dentry_open,
        .path_truncate       = tomoyo_path_truncate,
        .path_unlink         = tomoyo_path_unlink,
        .path_mkdir          = tomoyo_path_mkdir,
        .path_rmdir          = tomoyo_path_rmdir,
        .path_symlink        = tomoyo_path_symlink,
        .path_mknod          = tomoyo_path_mknod,
        .path_link           = tomoyo_path_link,
        .path_rename         = tomoyo_path_rename,
        .inode_getattr       = tomoyo_inode_getattr,
        .file_ioctl          = tomoyo_file_ioctl,
        .path_chmod          = tomoyo_path_chmod,
        .path_chown          = tomoyo_path_chown,
        .path_chroot         = tomoyo_path_chroot,
        .sb_mount            = tomoyo_sb_mount,
        .sb_umount           = tomoyo_sb_umount,
        .sb_pivotroot        = tomoyo_sb_pivotroot,
        .socket_bind         = tomoyo_socket_bind,
        .socket_connect      = tomoyo_socket_connect,
        .socket_listen       = tomoyo_socket_listen,
        .socket_sendmsg      = tomoyo_socket_sendmsg,
};

/* Lock for GC. */
struct srcu_struct tomoyo_ss;

/**
 * tomoyo_init - Register TOMOYO Linux as a LSM module.
 *
 * Returns 0.
 */
static int __init tomoyo_init(void)
{
        struct cred *cred = (struct cred *) current_cred();

        if (!security_module_enable(&tomoyo_security_ops))
                return 0;
        /* register ourselves with the security framework */
        if (register_security(&tomoyo_security_ops) ||
            init_srcu_struct(&tomoyo_ss))
                panic("Failure registering TOMOYO Linux");
        printk(KERN_INFO "TOMOYO Linux initialized\n");
        cred->security = &tomoyo_kernel_domain;
        tomoyo_mm_init();
        return 0;
}

security_initcall(tomoyo_init);