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-----BEGIN PGP SIGNATURE----- iQIVAwUAXRPObfu3V2unywtrAQJLKA//WENO5pZDHe49T+4GCY0ZmnGHKBUnU7g9 DUjxSNS8a/nwCyEdApZk9uHp2xsOedP6pjQ4VRWMQfrIPx0Yh9o3J+BQxvyP7PDf jEH+5CYC8dZnJJjjteWCcPEGrUoNb1YKfDRBU745YY+rLdHWvhHc27B6SYBg5BGT OwW3qyHvp0WMp7TehMALdnkqGph5gR5QMr45tOrH6DkGAhN8mAIKD699d3MqZG73 +S5KlQOlDlEVrxbD/BgzlzEJQUBQyq8hd61taBFT7LXBNlLJJOnMhd7UJY5IJE7J Vi9NpcLj4Emwv4wvZ2xneV0rMbsCbxRMKZLDRuqQ6Tm17xjpjro4n1ujneTAqmmy d+XlrVQ2ZMciMNmGleezOoBib9QbY5NWdilc2ls5ydFGiBVL73bIOYtEQNai8lWd LBBIIrxOmLO7bnipgqVKRnqeMdMkpWaLISoRfSeJbRt4lGxmka9bDBrSgONnxzJK JG+sB8ahSVZaBbhERW8DKnBz61Yf8ka7ijVvjH3zCXu0rbLTy+LLUz5kbzbBP9Fc LiUapLV/v420gD2ZRCgPQwtQui4TpBkSGJKS1Ippyn7LGBNCZLM4Y8vOoo4nqr7z RhpEKbKeOdVjORaYjO8Zttj8gN9rT6WnPcyCTHdNEnyjotU1ykyVBkzexj+VYvjM C3eIdjG7Jk0= =c2FO -----END PGP SIGNATURE----- Merge tag 'keys-request-20190626' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs Pull request_key improvements from David Howells: "These are all request_key()-related, including a fix and some improvements: - Fix the lack of a Link permission check on a key found by request_key(), thereby enabling request_key() to link keys that don't grant this permission to the target keyring (which must still grant Write permission). Note that the key must be in the caller's keyrings already to be found. - Invalidate used request_key authentication keys rather than revoking them, so that they get cleaned up immediately rather than hanging around till the expiry time is passed. - Move the RCU locks outwards from the keyring search functions so that a request_key_rcu() can be provided. This can be called in RCU mode, so it can't sleep and can't upcall - but it can be called from LOOKUP_RCU pathwalk mode. - Cache the latest positive result of request_key*() temporarily in task_struct so that filesystems that make a lot of request_key() calls during pathwalk can take advantage of it to avoid having to redo the searching. This requires CONFIG_KEYS_REQUEST_CACHE=y. It is assumed that the key just found is likely to be used multiple times in each step in an RCU pathwalk, and is likely to be reused for the next step too. Note that the cleanup of the cache is done on TIF_NOTIFY_RESUME, just before userspace resumes, and on exit" * tag 'keys-request-20190626' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: keys: Kill off request_key_async{,_with_auxdata} keys: Cache result of request_key*() temporarily in task_struct keys: Provide request_key_rcu() keys: Move the RCU locks outwards from the keyring search functions keys: Invalidate used request_key authentication keys keys: Fix request_key() lack of Link perm check on found key
876 lines
23 KiB
C
876 lines
23 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Task credentials management - see Documentation/security/credentials.rst
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*
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* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/export.h>
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#include <linux/cred.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include <linux/sched/coredump.h>
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#include <linux/key.h>
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#include <linux/keyctl.h>
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#include <linux/init_task.h>
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#include <linux/security.h>
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#include <linux/binfmts.h>
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#include <linux/cn_proc.h>
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#include <linux/uidgid.h>
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#if 0
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#define kdebug(FMT, ...) \
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printk("[%-5.5s%5u] " FMT "\n", \
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current->comm, current->pid, ##__VA_ARGS__)
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#else
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#define kdebug(FMT, ...) \
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do { \
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if (0) \
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no_printk("[%-5.5s%5u] " FMT "\n", \
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current->comm, current->pid, ##__VA_ARGS__); \
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} while (0)
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#endif
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static struct kmem_cache *cred_jar;
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/* init to 2 - one for init_task, one to ensure it is never freed */
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struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
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/*
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* The initial credentials for the initial task
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*/
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struct cred init_cred = {
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.usage = ATOMIC_INIT(4),
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#ifdef CONFIG_DEBUG_CREDENTIALS
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.subscribers = ATOMIC_INIT(2),
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.magic = CRED_MAGIC,
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#endif
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.uid = GLOBAL_ROOT_UID,
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.gid = GLOBAL_ROOT_GID,
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.suid = GLOBAL_ROOT_UID,
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.sgid = GLOBAL_ROOT_GID,
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.euid = GLOBAL_ROOT_UID,
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.egid = GLOBAL_ROOT_GID,
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.fsuid = GLOBAL_ROOT_UID,
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.fsgid = GLOBAL_ROOT_GID,
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.securebits = SECUREBITS_DEFAULT,
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.cap_inheritable = CAP_EMPTY_SET,
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.cap_permitted = CAP_FULL_SET,
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.cap_effective = CAP_FULL_SET,
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.cap_bset = CAP_FULL_SET,
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.user = INIT_USER,
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.user_ns = &init_user_ns,
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.group_info = &init_groups,
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};
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static inline void set_cred_subscribers(struct cred *cred, int n)
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{
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#ifdef CONFIG_DEBUG_CREDENTIALS
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atomic_set(&cred->subscribers, n);
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#endif
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}
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static inline int read_cred_subscribers(const struct cred *cred)
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{
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#ifdef CONFIG_DEBUG_CREDENTIALS
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return atomic_read(&cred->subscribers);
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#else
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return 0;
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#endif
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}
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static inline void alter_cred_subscribers(const struct cred *_cred, int n)
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{
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#ifdef CONFIG_DEBUG_CREDENTIALS
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struct cred *cred = (struct cred *) _cred;
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atomic_add(n, &cred->subscribers);
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#endif
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}
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/*
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* The RCU callback to actually dispose of a set of credentials
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*/
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static void put_cred_rcu(struct rcu_head *rcu)
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{
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struct cred *cred = container_of(rcu, struct cred, rcu);
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kdebug("put_cred_rcu(%p)", cred);
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#ifdef CONFIG_DEBUG_CREDENTIALS
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if (cred->magic != CRED_MAGIC_DEAD ||
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atomic_read(&cred->usage) != 0 ||
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read_cred_subscribers(cred) != 0)
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panic("CRED: put_cred_rcu() sees %p with"
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" mag %x, put %p, usage %d, subscr %d\n",
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cred, cred->magic, cred->put_addr,
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atomic_read(&cred->usage),
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read_cred_subscribers(cred));
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#else
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if (atomic_read(&cred->usage) != 0)
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panic("CRED: put_cred_rcu() sees %p with usage %d\n",
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cred, atomic_read(&cred->usage));
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#endif
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security_cred_free(cred);
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key_put(cred->session_keyring);
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key_put(cred->process_keyring);
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key_put(cred->thread_keyring);
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key_put(cred->request_key_auth);
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if (cred->group_info)
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put_group_info(cred->group_info);
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free_uid(cred->user);
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put_user_ns(cred->user_ns);
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kmem_cache_free(cred_jar, cred);
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}
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/**
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* __put_cred - Destroy a set of credentials
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* @cred: The record to release
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*
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* Destroy a set of credentials on which no references remain.
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*/
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void __put_cred(struct cred *cred)
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{
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kdebug("__put_cred(%p{%d,%d})", cred,
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atomic_read(&cred->usage),
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read_cred_subscribers(cred));
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BUG_ON(atomic_read(&cred->usage) != 0);
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#ifdef CONFIG_DEBUG_CREDENTIALS
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BUG_ON(read_cred_subscribers(cred) != 0);
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cred->magic = CRED_MAGIC_DEAD;
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cred->put_addr = __builtin_return_address(0);
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#endif
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BUG_ON(cred == current->cred);
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BUG_ON(cred == current->real_cred);
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call_rcu(&cred->rcu, put_cred_rcu);
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}
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EXPORT_SYMBOL(__put_cred);
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/*
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* Clean up a task's credentials when it exits
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*/
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void exit_creds(struct task_struct *tsk)
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{
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struct cred *cred;
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kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
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atomic_read(&tsk->cred->usage),
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read_cred_subscribers(tsk->cred));
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cred = (struct cred *) tsk->real_cred;
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tsk->real_cred = NULL;
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validate_creds(cred);
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alter_cred_subscribers(cred, -1);
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put_cred(cred);
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cred = (struct cred *) tsk->cred;
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tsk->cred = NULL;
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validate_creds(cred);
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alter_cred_subscribers(cred, -1);
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put_cred(cred);
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#ifdef CONFIG_KEYS_REQUEST_CACHE
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key_put(current->cached_requested_key);
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current->cached_requested_key = NULL;
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#endif
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}
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/**
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* get_task_cred - Get another task's objective credentials
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* @task: The task to query
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*
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* Get the objective credentials of a task, pinning them so that they can't go
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* away. Accessing a task's credentials directly is not permitted.
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*
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* The caller must also make sure task doesn't get deleted, either by holding a
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* ref on task or by holding tasklist_lock to prevent it from being unlinked.
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*/
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const struct cred *get_task_cred(struct task_struct *task)
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{
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const struct cred *cred;
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rcu_read_lock();
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do {
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cred = __task_cred((task));
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BUG_ON(!cred);
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} while (!get_cred_rcu(cred));
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rcu_read_unlock();
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return cred;
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}
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EXPORT_SYMBOL(get_task_cred);
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/*
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* Allocate blank credentials, such that the credentials can be filled in at a
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* later date without risk of ENOMEM.
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*/
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struct cred *cred_alloc_blank(void)
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{
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struct cred *new;
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new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
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if (!new)
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return NULL;
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atomic_set(&new->usage, 1);
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#ifdef CONFIG_DEBUG_CREDENTIALS
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new->magic = CRED_MAGIC;
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#endif
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if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
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goto error;
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return new;
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error:
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abort_creds(new);
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return NULL;
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}
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/**
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* prepare_creds - Prepare a new set of credentials for modification
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*
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* Prepare a new set of task credentials for modification. A task's creds
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* shouldn't generally be modified directly, therefore this function is used to
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* prepare a new copy, which the caller then modifies and then commits by
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* calling commit_creds().
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*
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* Preparation involves making a copy of the objective creds for modification.
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*
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* Returns a pointer to the new creds-to-be if successful, NULL otherwise.
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*
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* Call commit_creds() or abort_creds() to clean up.
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*/
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struct cred *prepare_creds(void)
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{
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struct task_struct *task = current;
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const struct cred *old;
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struct cred *new;
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validate_process_creds();
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new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
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if (!new)
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return NULL;
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kdebug("prepare_creds() alloc %p", new);
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old = task->cred;
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memcpy(new, old, sizeof(struct cred));
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atomic_set(&new->usage, 1);
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set_cred_subscribers(new, 0);
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get_group_info(new->group_info);
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get_uid(new->user);
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get_user_ns(new->user_ns);
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#ifdef CONFIG_KEYS
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key_get(new->session_keyring);
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key_get(new->process_keyring);
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key_get(new->thread_keyring);
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key_get(new->request_key_auth);
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#endif
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#ifdef CONFIG_SECURITY
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new->security = NULL;
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#endif
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if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
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goto error;
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validate_creds(new);
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return new;
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error:
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abort_creds(new);
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return NULL;
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}
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EXPORT_SYMBOL(prepare_creds);
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/*
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* Prepare credentials for current to perform an execve()
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* - The caller must hold ->cred_guard_mutex
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*/
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struct cred *prepare_exec_creds(void)
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{
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struct cred *new;
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new = prepare_creds();
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if (!new)
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return new;
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#ifdef CONFIG_KEYS
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/* newly exec'd tasks don't get a thread keyring */
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key_put(new->thread_keyring);
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new->thread_keyring = NULL;
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/* inherit the session keyring; new process keyring */
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key_put(new->process_keyring);
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new->process_keyring = NULL;
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#endif
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return new;
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}
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/*
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* Copy credentials for the new process created by fork()
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*
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* We share if we can, but under some circumstances we have to generate a new
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* set.
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*
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* The new process gets the current process's subjective credentials as its
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* objective and subjective credentials
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*/
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int copy_creds(struct task_struct *p, unsigned long clone_flags)
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{
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struct cred *new;
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int ret;
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#ifdef CONFIG_KEYS_REQUEST_CACHE
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p->cached_requested_key = NULL;
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#endif
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if (
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#ifdef CONFIG_KEYS
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!p->cred->thread_keyring &&
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#endif
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clone_flags & CLONE_THREAD
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) {
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p->real_cred = get_cred(p->cred);
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get_cred(p->cred);
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alter_cred_subscribers(p->cred, 2);
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kdebug("share_creds(%p{%d,%d})",
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p->cred, atomic_read(&p->cred->usage),
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read_cred_subscribers(p->cred));
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atomic_inc(&p->cred->user->processes);
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return 0;
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}
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new = prepare_creds();
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if (!new)
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return -ENOMEM;
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if (clone_flags & CLONE_NEWUSER) {
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ret = create_user_ns(new);
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if (ret < 0)
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goto error_put;
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}
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#ifdef CONFIG_KEYS
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/* new threads get their own thread keyrings if their parent already
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* had one */
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if (new->thread_keyring) {
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key_put(new->thread_keyring);
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new->thread_keyring = NULL;
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if (clone_flags & CLONE_THREAD)
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install_thread_keyring_to_cred(new);
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}
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/* The process keyring is only shared between the threads in a process;
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* anything outside of those threads doesn't inherit.
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*/
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if (!(clone_flags & CLONE_THREAD)) {
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key_put(new->process_keyring);
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new->process_keyring = NULL;
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}
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#endif
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atomic_inc(&new->user->processes);
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p->cred = p->real_cred = get_cred(new);
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alter_cred_subscribers(new, 2);
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validate_creds(new);
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return 0;
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error_put:
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put_cred(new);
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return ret;
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}
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static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)
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{
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const struct user_namespace *set_ns = set->user_ns;
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const struct user_namespace *subset_ns = subset->user_ns;
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/* If the two credentials are in the same user namespace see if
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* the capabilities of subset are a subset of set.
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*/
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if (set_ns == subset_ns)
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return cap_issubset(subset->cap_permitted, set->cap_permitted);
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/* The credentials are in a different user namespaces
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* therefore one is a subset of the other only if a set is an
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* ancestor of subset and set->euid is owner of subset or one
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* of subsets ancestors.
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*/
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for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) {
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if ((set_ns == subset_ns->parent) &&
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uid_eq(subset_ns->owner, set->euid))
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return true;
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}
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return false;
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}
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/**
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* commit_creds - Install new credentials upon the current task
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* @new: The credentials to be assigned
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*
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* Install a new set of credentials to the current task, using RCU to replace
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* the old set. Both the objective and the subjective credentials pointers are
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* updated. This function may not be called if the subjective credentials are
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* in an overridden state.
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*
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* This function eats the caller's reference to the new credentials.
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*
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* Always returns 0 thus allowing this function to be tail-called at the end
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* of, say, sys_setgid().
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*/
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int commit_creds(struct cred *new)
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{
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struct task_struct *task = current;
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const struct cred *old = task->real_cred;
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kdebug("commit_creds(%p{%d,%d})", new,
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atomic_read(&new->usage),
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read_cred_subscribers(new));
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BUG_ON(task->cred != old);
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#ifdef CONFIG_DEBUG_CREDENTIALS
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BUG_ON(read_cred_subscribers(old) < 2);
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validate_creds(old);
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validate_creds(new);
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#endif
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BUG_ON(atomic_read(&new->usage) < 1);
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get_cred(new); /* we will require a ref for the subj creds too */
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/* dumpability changes */
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if (!uid_eq(old->euid, new->euid) ||
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!gid_eq(old->egid, new->egid) ||
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!uid_eq(old->fsuid, new->fsuid) ||
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!gid_eq(old->fsgid, new->fsgid) ||
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!cred_cap_issubset(old, new)) {
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if (task->mm)
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set_dumpable(task->mm, suid_dumpable);
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task->pdeath_signal = 0;
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/*
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* If a task drops privileges and becomes nondumpable,
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* the dumpability change must become visible before
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* the credential change; otherwise, a __ptrace_may_access()
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* racing with this change may be able to attach to a task it
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* shouldn't be able to attach to (as if the task had dropped
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* privileges without becoming nondumpable).
|
|
* Pairs with a read barrier in __ptrace_may_access().
|
|
*/
|
|
smp_wmb();
|
|
}
|
|
|
|
/* alter the thread keyring */
|
|
if (!uid_eq(new->fsuid, old->fsuid))
|
|
key_fsuid_changed(new);
|
|
if (!gid_eq(new->fsgid, old->fsgid))
|
|
key_fsgid_changed(new);
|
|
|
|
/* do it
|
|
* RLIMIT_NPROC limits on user->processes have already been checked
|
|
* in set_user().
|
|
*/
|
|
alter_cred_subscribers(new, 2);
|
|
if (new->user != old->user)
|
|
atomic_inc(&new->user->processes);
|
|
rcu_assign_pointer(task->real_cred, new);
|
|
rcu_assign_pointer(task->cred, new);
|
|
if (new->user != old->user)
|
|
atomic_dec(&old->user->processes);
|
|
alter_cred_subscribers(old, -2);
|
|
|
|
/* send notifications */
|
|
if (!uid_eq(new->uid, old->uid) ||
|
|
!uid_eq(new->euid, old->euid) ||
|
|
!uid_eq(new->suid, old->suid) ||
|
|
!uid_eq(new->fsuid, old->fsuid))
|
|
proc_id_connector(task, PROC_EVENT_UID);
|
|
|
|
if (!gid_eq(new->gid, old->gid) ||
|
|
!gid_eq(new->egid, old->egid) ||
|
|
!gid_eq(new->sgid, old->sgid) ||
|
|
!gid_eq(new->fsgid, old->fsgid))
|
|
proc_id_connector(task, PROC_EVENT_GID);
|
|
|
|
/* release the old obj and subj refs both */
|
|
put_cred(old);
|
|
put_cred(old);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(commit_creds);
|
|
|
|
/**
|
|
* abort_creds - Discard a set of credentials and unlock the current task
|
|
* @new: The credentials that were going to be applied
|
|
*
|
|
* Discard a set of credentials that were under construction and unlock the
|
|
* current task.
|
|
*/
|
|
void abort_creds(struct cred *new)
|
|
{
|
|
kdebug("abort_creds(%p{%d,%d})", new,
|
|
atomic_read(&new->usage),
|
|
read_cred_subscribers(new));
|
|
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
BUG_ON(read_cred_subscribers(new) != 0);
|
|
#endif
|
|
BUG_ON(atomic_read(&new->usage) < 1);
|
|
put_cred(new);
|
|
}
|
|
EXPORT_SYMBOL(abort_creds);
|
|
|
|
/**
|
|
* override_creds - Override the current process's subjective credentials
|
|
* @new: The credentials to be assigned
|
|
*
|
|
* Install a set of temporary override subjective credentials on the current
|
|
* process, returning the old set for later reversion.
|
|
*/
|
|
const struct cred *override_creds(const struct cred *new)
|
|
{
|
|
const struct cred *old = current->cred;
|
|
|
|
kdebug("override_creds(%p{%d,%d})", new,
|
|
atomic_read(&new->usage),
|
|
read_cred_subscribers(new));
|
|
|
|
validate_creds(old);
|
|
validate_creds(new);
|
|
get_cred(new);
|
|
alter_cred_subscribers(new, 1);
|
|
rcu_assign_pointer(current->cred, new);
|
|
alter_cred_subscribers(old, -1);
|
|
|
|
kdebug("override_creds() = %p{%d,%d}", old,
|
|
atomic_read(&old->usage),
|
|
read_cred_subscribers(old));
|
|
return old;
|
|
}
|
|
EXPORT_SYMBOL(override_creds);
|
|
|
|
/**
|
|
* revert_creds - Revert a temporary subjective credentials override
|
|
* @old: The credentials to be restored
|
|
*
|
|
* Revert a temporary set of override subjective credentials to an old set,
|
|
* discarding the override set.
|
|
*/
|
|
void revert_creds(const struct cred *old)
|
|
{
|
|
const struct cred *override = current->cred;
|
|
|
|
kdebug("revert_creds(%p{%d,%d})", old,
|
|
atomic_read(&old->usage),
|
|
read_cred_subscribers(old));
|
|
|
|
validate_creds(old);
|
|
validate_creds(override);
|
|
alter_cred_subscribers(old, 1);
|
|
rcu_assign_pointer(current->cred, old);
|
|
alter_cred_subscribers(override, -1);
|
|
put_cred(override);
|
|
}
|
|
EXPORT_SYMBOL(revert_creds);
|
|
|
|
/**
|
|
* cred_fscmp - Compare two credentials with respect to filesystem access.
|
|
* @a: The first credential
|
|
* @b: The second credential
|
|
*
|
|
* cred_cmp() will return zero if both credentials have the same
|
|
* fsuid, fsgid, and supplementary groups. That is, if they will both
|
|
* provide the same access to files based on mode/uid/gid.
|
|
* If the credentials are different, then either -1 or 1 will
|
|
* be returned depending on whether @a comes before or after @b
|
|
* respectively in an arbitrary, but stable, ordering of credentials.
|
|
*
|
|
* Return: -1, 0, or 1 depending on comparison
|
|
*/
|
|
int cred_fscmp(const struct cred *a, const struct cred *b)
|
|
{
|
|
struct group_info *ga, *gb;
|
|
int g;
|
|
|
|
if (a == b)
|
|
return 0;
|
|
if (uid_lt(a->fsuid, b->fsuid))
|
|
return -1;
|
|
if (uid_gt(a->fsuid, b->fsuid))
|
|
return 1;
|
|
|
|
if (gid_lt(a->fsgid, b->fsgid))
|
|
return -1;
|
|
if (gid_gt(a->fsgid, b->fsgid))
|
|
return 1;
|
|
|
|
ga = a->group_info;
|
|
gb = b->group_info;
|
|
if (ga == gb)
|
|
return 0;
|
|
if (ga == NULL)
|
|
return -1;
|
|
if (gb == NULL)
|
|
return 1;
|
|
if (ga->ngroups < gb->ngroups)
|
|
return -1;
|
|
if (ga->ngroups > gb->ngroups)
|
|
return 1;
|
|
|
|
for (g = 0; g < ga->ngroups; g++) {
|
|
if (gid_lt(ga->gid[g], gb->gid[g]))
|
|
return -1;
|
|
if (gid_gt(ga->gid[g], gb->gid[g]))
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(cred_fscmp);
|
|
|
|
/*
|
|
* initialise the credentials stuff
|
|
*/
|
|
void __init cred_init(void)
|
|
{
|
|
/* allocate a slab in which we can store credentials */
|
|
cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
|
|
}
|
|
|
|
/**
|
|
* prepare_kernel_cred - Prepare a set of credentials for a kernel service
|
|
* @daemon: A userspace daemon to be used as a reference
|
|
*
|
|
* Prepare a set of credentials for a kernel service. This can then be used to
|
|
* override a task's own credentials so that work can be done on behalf of that
|
|
* task that requires a different subjective context.
|
|
*
|
|
* @daemon is used to provide a base for the security record, but can be NULL.
|
|
* If @daemon is supplied, then the security data will be derived from that;
|
|
* otherwise they'll be set to 0 and no groups, full capabilities and no keys.
|
|
*
|
|
* The caller may change these controls afterwards if desired.
|
|
*
|
|
* Returns the new credentials or NULL if out of memory.
|
|
*
|
|
* Does not take, and does not return holding current->cred_replace_mutex.
|
|
*/
|
|
struct cred *prepare_kernel_cred(struct task_struct *daemon)
|
|
{
|
|
const struct cred *old;
|
|
struct cred *new;
|
|
|
|
new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
|
|
if (!new)
|
|
return NULL;
|
|
|
|
kdebug("prepare_kernel_cred() alloc %p", new);
|
|
|
|
if (daemon)
|
|
old = get_task_cred(daemon);
|
|
else
|
|
old = get_cred(&init_cred);
|
|
|
|
validate_creds(old);
|
|
|
|
*new = *old;
|
|
atomic_set(&new->usage, 1);
|
|
set_cred_subscribers(new, 0);
|
|
get_uid(new->user);
|
|
get_user_ns(new->user_ns);
|
|
get_group_info(new->group_info);
|
|
|
|
#ifdef CONFIG_KEYS
|
|
new->session_keyring = NULL;
|
|
new->process_keyring = NULL;
|
|
new->thread_keyring = NULL;
|
|
new->request_key_auth = NULL;
|
|
new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
|
|
#endif
|
|
|
|
#ifdef CONFIG_SECURITY
|
|
new->security = NULL;
|
|
#endif
|
|
if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
|
|
goto error;
|
|
|
|
put_cred(old);
|
|
validate_creds(new);
|
|
return new;
|
|
|
|
error:
|
|
put_cred(new);
|
|
put_cred(old);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(prepare_kernel_cred);
|
|
|
|
/**
|
|
* set_security_override - Set the security ID in a set of credentials
|
|
* @new: The credentials to alter
|
|
* @secid: The LSM security ID to set
|
|
*
|
|
* Set the LSM security ID in a set of credentials so that the subjective
|
|
* security is overridden when an alternative set of credentials is used.
|
|
*/
|
|
int set_security_override(struct cred *new, u32 secid)
|
|
{
|
|
return security_kernel_act_as(new, secid);
|
|
}
|
|
EXPORT_SYMBOL(set_security_override);
|
|
|
|
/**
|
|
* set_security_override_from_ctx - Set the security ID in a set of credentials
|
|
* @new: The credentials to alter
|
|
* @secctx: The LSM security context to generate the security ID from.
|
|
*
|
|
* Set the LSM security ID in a set of credentials so that the subjective
|
|
* security is overridden when an alternative set of credentials is used. The
|
|
* security ID is specified in string form as a security context to be
|
|
* interpreted by the LSM.
|
|
*/
|
|
int set_security_override_from_ctx(struct cred *new, const char *secctx)
|
|
{
|
|
u32 secid;
|
|
int ret;
|
|
|
|
ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
return set_security_override(new, secid);
|
|
}
|
|
EXPORT_SYMBOL(set_security_override_from_ctx);
|
|
|
|
/**
|
|
* set_create_files_as - Set the LSM file create context in a set of credentials
|
|
* @new: The credentials to alter
|
|
* @inode: The inode to take the context from
|
|
*
|
|
* Change the LSM file creation context in a set of credentials to be the same
|
|
* as the object context of the specified inode, so that the new inodes have
|
|
* the same MAC context as that inode.
|
|
*/
|
|
int set_create_files_as(struct cred *new, struct inode *inode)
|
|
{
|
|
if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid))
|
|
return -EINVAL;
|
|
new->fsuid = inode->i_uid;
|
|
new->fsgid = inode->i_gid;
|
|
return security_kernel_create_files_as(new, inode);
|
|
}
|
|
EXPORT_SYMBOL(set_create_files_as);
|
|
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
|
|
bool creds_are_invalid(const struct cred *cred)
|
|
{
|
|
if (cred->magic != CRED_MAGIC)
|
|
return true;
|
|
return false;
|
|
}
|
|
EXPORT_SYMBOL(creds_are_invalid);
|
|
|
|
/*
|
|
* dump invalid credentials
|
|
*/
|
|
static void dump_invalid_creds(const struct cred *cred, const char *label,
|
|
const struct task_struct *tsk)
|
|
{
|
|
printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
|
|
label, cred,
|
|
cred == &init_cred ? "[init]" : "",
|
|
cred == tsk->real_cred ? "[real]" : "",
|
|
cred == tsk->cred ? "[eff]" : "");
|
|
printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
|
|
cred->magic, cred->put_addr);
|
|
printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
|
|
atomic_read(&cred->usage),
|
|
read_cred_subscribers(cred));
|
|
printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
|
|
from_kuid_munged(&init_user_ns, cred->uid),
|
|
from_kuid_munged(&init_user_ns, cred->euid),
|
|
from_kuid_munged(&init_user_ns, cred->suid),
|
|
from_kuid_munged(&init_user_ns, cred->fsuid));
|
|
printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
|
|
from_kgid_munged(&init_user_ns, cred->gid),
|
|
from_kgid_munged(&init_user_ns, cred->egid),
|
|
from_kgid_munged(&init_user_ns, cred->sgid),
|
|
from_kgid_munged(&init_user_ns, cred->fsgid));
|
|
#ifdef CONFIG_SECURITY
|
|
printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
|
|
if ((unsigned long) cred->security >= PAGE_SIZE &&
|
|
(((unsigned long) cred->security & 0xffffff00) !=
|
|
(POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
|
|
printk(KERN_ERR "CRED: ->security {%x, %x}\n",
|
|
((u32*)cred->security)[0],
|
|
((u32*)cred->security)[1]);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* report use of invalid credentials
|
|
*/
|
|
void __invalid_creds(const struct cred *cred, const char *file, unsigned line)
|
|
{
|
|
printk(KERN_ERR "CRED: Invalid credentials\n");
|
|
printk(KERN_ERR "CRED: At %s:%u\n", file, line);
|
|
dump_invalid_creds(cred, "Specified", current);
|
|
BUG();
|
|
}
|
|
EXPORT_SYMBOL(__invalid_creds);
|
|
|
|
/*
|
|
* check the credentials on a process
|
|
*/
|
|
void __validate_process_creds(struct task_struct *tsk,
|
|
const char *file, unsigned line)
|
|
{
|
|
if (tsk->cred == tsk->real_cred) {
|
|
if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
|
|
creds_are_invalid(tsk->cred)))
|
|
goto invalid_creds;
|
|
} else {
|
|
if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
|
|
read_cred_subscribers(tsk->cred) < 1 ||
|
|
creds_are_invalid(tsk->real_cred) ||
|
|
creds_are_invalid(tsk->cred)))
|
|
goto invalid_creds;
|
|
}
|
|
return;
|
|
|
|
invalid_creds:
|
|
printk(KERN_ERR "CRED: Invalid process credentials\n");
|
|
printk(KERN_ERR "CRED: At %s:%u\n", file, line);
|
|
|
|
dump_invalid_creds(tsk->real_cred, "Real", tsk);
|
|
if (tsk->cred != tsk->real_cred)
|
|
dump_invalid_creds(tsk->cred, "Effective", tsk);
|
|
else
|
|
printk(KERN_ERR "CRED: Effective creds == Real creds\n");
|
|
BUG();
|
|
}
|
|
EXPORT_SYMBOL(__validate_process_creds);
|
|
|
|
/*
|
|
* check creds for do_exit()
|
|
*/
|
|
void validate_creds_for_do_exit(struct task_struct *tsk)
|
|
{
|
|
kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
|
|
tsk->real_cred, tsk->cred,
|
|
atomic_read(&tsk->cred->usage),
|
|
read_cred_subscribers(tsk->cred));
|
|
|
|
__validate_process_creds(tsk, __FILE__, __LINE__);
|
|
}
|
|
|
|
#endif /* CONFIG_DEBUG_CREDENTIALS */
|