linux/security/security.c

/*
 * Security plug functions
 *
 * Copyright (C) 2001 WireX Communications, Inc <chris@wirex.com>
 * Copyright (C) 2001-2002 Greg Kroah-Hartman <greg@kroah.com>
 * Copyright (C) 2001 Networks Associates Technology, Inc <ssmalley@nai.com>
 *
 *	This program is free software; you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License as published by
 *	the Free Software Foundation; either version 2 of the License, or
 *	(at your option) any later version.
 */

#include <linux/capability.h>
#include <linux/dcache.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/lsm_hooks.h>
#include <linux/integrity.h>
#include <linux/ima.h>
#include <linux/evm.h>
#include <linux/fsnotify.h>
#include <linux/mman.h>
#include <linux/mount.h>
#include <linux/personality.h>
#include <linux/backing-dev.h>
#include <net/flow.h>

#define MAX_LSM_EVM_XATTR	2

/* Maximum number of letters for an LSM name string */
#define SECURITY_NAME_MAX	10

/* Boot-time LSM user choice */
static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
	CONFIG_DEFAULT_SECURITY;

static void __init do_security_initcalls(void)
{
	initcall_t *call;
	call = __security_initcall_start;
	while (call < __security_initcall_end) {
		(*call) ();
		call++;
	}
}

/**
 * security_init - initializes the security framework
 *
 * This should be called early in the kernel initialization sequence.
 */
int __init security_init(void)
{
	pr_info("Security Framework initialized\n");

	/*
	 * Load minor LSMs, with the capability module always first.
	 */
	capability_add_hooks();
	yama_add_hooks();
	loadpin_add_hooks();

	/*
	 * Load all the remaining security modules.
	 */
	do_security_initcalls();

	return 0;
}

/* Save user chosen LSM */
static int __init choose_lsm(char *str)
{
	strncpy(chosen_lsm, str, SECURITY_NAME_MAX);
	return 1;
}
__setup("security=", choose_lsm);

/**
 * security_module_enable - Load given security module on boot ?
 * @module: the name of the module
 *
 * Each LSM must pass this method before registering its own operations
 * to avoid security registration races. This method may also be used
 * to check if your LSM is currently loaded during kernel initialization.
 *
 * Return true if:
 *	-The passed LSM is the one chosen by user at boot time,
 *	-or the passed LSM is configured as the default and the user did not
 *	 choose an alternate LSM at boot time.
 * Otherwise, return false.
 */
int __init security_module_enable(const char *module)
{
	return !strcmp(module, chosen_lsm);
}

/*
 * Hook list operation macros.
 *
 * call_void_hook:
 *	This is a hook that does not return a value.
 *
 * call_int_hook:
 *	This is a hook that returns a value.
 */

#define call_void_hook(FUNC, ...)				\
	do {							\
		struct security_hook_list *P;			\
								\
		list_for_each_entry(P, &security_hook_heads.FUNC, list)	\
			P->hook.FUNC(__VA_ARGS__);		\
	} while (0)

#define call_int_hook(FUNC, IRC, ...) ({			\
	int RC = IRC;						\
	do {							\
		struct security_hook_list *P;			\
								\
		list_for_each_entry(P, &security_hook_heads.FUNC, list) { \
			RC = P->hook.FUNC(__VA_ARGS__);		\
			if (RC != 0)				\
				break;				\
		}						\
	} while (0);						\
	RC;							\
})

/* Security operations */

int security_binder_set_context_mgr(struct task_struct *mgr)
{
	return call_int_hook(binder_set_context_mgr, 0, mgr);
}

int security_binder_transaction(struct task_struct *from,
				struct task_struct *to)
{
	return call_int_hook(binder_transaction, 0, from, to);
}

int security_binder_transfer_binder(struct task_struct *from,
				    struct task_struct *to)
{
	return call_int_hook(binder_transfer_binder, 0, from, to);
}

int security_binder_transfer_file(struct task_struct *from,
				  struct task_struct *to, struct file *file)
{
	return call_int_hook(binder_transfer_file, 0, from, to, file);
}

int security_ptrace_access_check(struct task_struct *child, unsigned int mode)
{
	return call_int_hook(ptrace_access_check, 0, child, mode);
}

int security_ptrace_traceme(struct task_struct *parent)
{
	return call_int_hook(ptrace_traceme, 0, parent);
}

int security_capget(struct task_struct *target,
		     kernel_cap_t *effective,
		     kernel_cap_t *inheritable,
		     kernel_cap_t *permitted)
{
	return call_int_hook(capget, 0, target,
				effective, inheritable, permitted);
}

int security_capset(struct cred *new, const struct cred *old,
		    const kernel_cap_t *effective,
		    const kernel_cap_t *inheritable,
		    const kernel_cap_t *permitted)
{
	return call_int_hook(capset, 0, new, old,
				effective, inheritable, permitted);
}

int security_capable(const struct cred *cred, struct user_namespace *ns,
		     int cap)
{
	return call_int_hook(capable, 0, cred, ns, cap, SECURITY_CAP_AUDIT);
}

int security_capable_noaudit(const struct cred *cred, struct user_namespace *ns,
			     int cap)
{
	return call_int_hook(capable, 0, cred, ns, cap, SECURITY_CAP_NOAUDIT);
}

int security_quotactl(int cmds, int type, int id, struct super_block *sb)
{
	return call_int_hook(quotactl, 0, cmds, type, id, sb);
}

int security_quota_on(struct dentry *dentry)
{
	return call_int_hook(quota_on, 0, dentry);
}

int security_syslog(int type)
{
	return call_int_hook(syslog, 0, type);
}

int security_settime64(const struct timespec64 *ts, const struct timezone *tz)
{
	return call_int_hook(settime, 0, ts, tz);
}

int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
{
	struct security_hook_list *hp;
	int cap_sys_admin = 1;
	int rc;

	/*
	 * The module will respond with a positive value if
	 * it thinks the __vm_enough_memory() call should be
	 * made with the cap_sys_admin set. If all of the modules
	 * agree that it should be set it will. If any module
	 * thinks it should not be set it won't.
	 */
	list_for_each_entry(hp, &security_hook_heads.vm_enough_memory, list) {
		rc = hp->hook.vm_enough_memory(mm, pages);
		if (rc <= 0) {
			cap_sys_admin = 0;
			break;
		}
	}
	return __vm_enough_memory(mm, pages, cap_sys_admin);
}

int security_bprm_set_creds(struct linux_binprm *bprm)
{
	return call_int_hook(bprm_set_creds, 0, bprm);
}

int security_bprm_check(struct linux_binprm *bprm)
{
	int ret;

	ret = call_int_hook(bprm_check_security, 0, bprm);
	if (ret)
		return ret;
	return ima_bprm_check(bprm);
}

void security_bprm_committing_creds(struct linux_binprm *bprm)
{
	call_void_hook(bprm_committing_creds, bprm);
}

void security_bprm_committed_creds(struct linux_binprm *bprm)
{
	call_void_hook(bprm_committed_creds, bprm);
}

int security_bprm_secureexec(struct linux_binprm *bprm)
{
	return call_int_hook(bprm_secureexec, 0, bprm);
}

int security_sb_alloc(struct super_block *sb)
{
	return call_int_hook(sb_alloc_security, 0, sb);
}

void security_sb_free(struct super_block *sb)
{
	call_void_hook(sb_free_security, sb);
}

int security_sb_copy_data(char *orig, char *copy)
{
	return call_int_hook(sb_copy_data, 0, orig, copy);
}
EXPORT_SYMBOL(security_sb_copy_data);

int security_sb_remount(struct super_block *sb, void *data)
{
	return call_int_hook(sb_remount, 0, sb, data);
}

int security_sb_kern_mount(struct super_block *sb, int flags, void *data)
{
	return call_int_hook(sb_kern_mount, 0, sb, flags, data);
}

int security_sb_show_options(struct seq_file *m, struct super_block *sb)
{
	return call_int_hook(sb_show_options, 0, m, sb);
}

int security_sb_statfs(struct dentry *dentry)
{
	return call_int_hook(sb_statfs, 0, dentry);
}

int security_sb_mount(const char *dev_name, const struct path *path,
                       const char *type, unsigned long flags, void *data)
{
	return call_int_hook(sb_mount, 0, dev_name, path, type, flags, data);
}

int security_sb_umount(struct vfsmount *mnt, int flags)
{
	return call_int_hook(sb_umount, 0, mnt, flags);
}

int security_sb_pivotroot(const struct path *old_path, const struct path *new_path)
{
	return call_int_hook(sb_pivotroot, 0, old_path, new_path);
}

int security_sb_set_mnt_opts(struct super_block *sb,
				struct security_mnt_opts *opts,
				unsigned long kern_flags,
				unsigned long *set_kern_flags)
{
	return call_int_hook(sb_set_mnt_opts,
				opts->num_mnt_opts ? -EOPNOTSUPP : 0, sb,
				opts, kern_flags, set_kern_flags);
}
EXPORT_SYMBOL(security_sb_set_mnt_opts);

int security_sb_clone_mnt_opts(const struct super_block *oldsb,
				struct super_block *newsb)
{
	return call_int_hook(sb_clone_mnt_opts, 0, oldsb, newsb);
}
EXPORT_SYMBOL(security_sb_clone_mnt_opts);

int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts)
{
	return call_int_hook(sb_parse_opts_str, 0, options, opts);
}
EXPORT_SYMBOL(security_sb_parse_opts_str);

int security_inode_alloc(struct inode *inode)
{
	inode->i_security = NULL;
	return call_int_hook(inode_alloc_security, 0, inode);
}

void security_inode_free(struct inode *inode)
{
	integrity_inode_free(inode);
	call_void_hook(inode_free_security, inode);
}

int security_dentry_init_security(struct dentry *dentry, int mode,
					struct qstr *name, void **ctx,
					u32 *ctxlen)
{
	return call_int_hook(dentry_init_security, -EOPNOTSUPP, dentry, mode,
				name, ctx, ctxlen);
}
EXPORT_SYMBOL(security_dentry_init_security);

int security_inode_init_security(struct inode *inode, struct inode *dir,
				 const struct qstr *qstr,
				 const initxattrs initxattrs, void *fs_data)
{
	struct xattr new_xattrs[MAX_LSM_EVM_XATTR + 1];
	struct xattr *lsm_xattr, *evm_xattr, *xattr;
	int ret;

	if (unlikely(IS_PRIVATE(inode)))
		return 0;

	if (!initxattrs)
		return call_int_hook(inode_init_security, -EOPNOTSUPP, inode,
				     dir, qstr, NULL, NULL, NULL);
	memset(new_xattrs, 0, sizeof(new_xattrs));
	lsm_xattr = new_xattrs;
	ret = call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, qstr,
						&lsm_xattr->name,
						&lsm_xattr->value,
						&lsm_xattr->value_len);
	if (ret)
		goto out;

	evm_xattr = lsm_xattr + 1;
	ret = evm_inode_init_security(inode, lsm_xattr, evm_xattr);
	if (ret)
		goto out;
	ret = initxattrs(inode, new_xattrs, fs_data);
out:
	for (xattr = new_xattrs; xattr->value != NULL; xattr++)
		kfree(xattr->value);
	return (ret == -EOPNOTSUPP) ? 0 : ret;
}
EXPORT_SYMBOL(security_inode_init_security);

int security_old_inode_init_security(struct inode *inode, struct inode *dir,
				     const struct qstr *qstr, const char **name,
				     void **value, size_t *len)
{
	if (unlikely(IS_PRIVATE(inode)))
		return -EOPNOTSUPP;
	return call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir,
			     qstr, name, value, len);