* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
+
+#define pr_fmt(fmt) "CRED: " fmt
+
#include <linux/export.h>
#include <linux/cred.h>
#include <linux/slab.h>
static struct kmem_cache *cred_jar;
/* init to 2 - one for init_task, one to ensure it is never freed */
-struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
+static struct group_info init_groups = { .usage = REFCOUNT_INIT(2) };
/*
* The initial credentials for the initial task
*/
struct cred init_cred = {
.usage = ATOMIC_INIT(4),
-#ifdef CONFIG_DEBUG_CREDENTIALS
- .subscribers = ATOMIC_INIT(2),
- .magic = CRED_MAGIC,
-#endif
.uid = GLOBAL_ROOT_UID,
.gid = GLOBAL_ROOT_GID,
.suid = GLOBAL_ROOT_UID,
.user = INIT_USER,
.user_ns = &init_user_ns,
.group_info = &init_groups,
+ .ucounts = &init_ucounts,
};
-static inline void set_cred_subscribers(struct cred *cred, int n)
-{
-#ifdef CONFIG_DEBUG_CREDENTIALS
- atomic_set(&cred->subscribers, n);
-#endif
-}
-
-static inline int read_cred_subscribers(const struct cred *cred)
-{
-#ifdef CONFIG_DEBUG_CREDENTIALS
- return atomic_read(&cred->subscribers);
-#else
- return 0;
-#endif
-}
-
-static inline void alter_cred_subscribers(const struct cred *_cred, int n)
-{
-#ifdef CONFIG_DEBUG_CREDENTIALS
- struct cred *cred = (struct cred *) _cred;
-
- atomic_add(n, &cred->subscribers);
-#endif
-}
-
/*
* The RCU callback to actually dispose of a set of credentials
*/
kdebug("put_cred_rcu(%p)", cred);
-#ifdef CONFIG_DEBUG_CREDENTIALS
- if (cred->magic != CRED_MAGIC_DEAD ||
- atomic_read(&cred->usage) != 0 ||
- read_cred_subscribers(cred) != 0)
- panic("CRED: put_cred_rcu() sees %p with"
- " mag %x, put %p, usage %d, subscr %d\n",
- cred, cred->magic, cred->put_addr,
- atomic_read(&cred->usage),
- read_cred_subscribers(cred));
-#else
- if (atomic_read(&cred->usage) != 0)
- panic("CRED: put_cred_rcu() sees %p with usage %d\n",
- cred, atomic_read(&cred->usage));
-#endif
+ if (atomic_long_read(&cred->usage) != 0)
+ panic("CRED: put_cred_rcu() sees %p with usage %ld\n",
+ cred, atomic_long_read(&cred->usage));
security_cred_free(cred);
key_put(cred->session_keyring);
if (cred->group_info)
put_group_info(cred->group_info);
free_uid(cred->user);
+ if (cred->ucounts)
+ put_ucounts(cred->ucounts);
put_user_ns(cred->user_ns);
kmem_cache_free(cred_jar, cred);
}
*/
void __put_cred(struct cred *cred)
{
- kdebug("__put_cred(%p{%d,%d})", cred,
- atomic_read(&cred->usage),
- read_cred_subscribers(cred));
-
- BUG_ON(atomic_read(&cred->usage) != 0);
-#ifdef CONFIG_DEBUG_CREDENTIALS
- BUG_ON(read_cred_subscribers(cred) != 0);
- cred->magic = CRED_MAGIC_DEAD;
- cred->put_addr = __builtin_return_address(0);
-#endif
+ kdebug("__put_cred(%p{%ld})", cred,
+ atomic_long_read(&cred->usage));
+
+ BUG_ON(atomic_long_read(&cred->usage) != 0);
BUG_ON(cred == current->cred);
BUG_ON(cred == current->real_cred);
- call_rcu(&cred->rcu, put_cred_rcu);
+ if (cred->non_rcu)
+ put_cred_rcu(&cred->rcu);
+ else
+ call_rcu(&cred->rcu, put_cred_rcu);
}
EXPORT_SYMBOL(__put_cred);
*/
void exit_creds(struct task_struct *tsk)
{
- struct cred *cred;
+ struct cred *real_cred, *cred;
- kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
- atomic_read(&tsk->cred->usage),
- read_cred_subscribers(tsk->cred));
+ kdebug("exit_creds(%u,%p,%p,{%ld})", tsk->pid, tsk->real_cred, tsk->cred,
+ atomic_long_read(&tsk->cred->usage));
- cred = (struct cred *) tsk->real_cred;
+ real_cred = (struct cred *) tsk->real_cred;
tsk->real_cred = NULL;
- validate_creds(cred);
- alter_cred_subscribers(cred, -1);
- put_cred(cred);
cred = (struct cred *) tsk->cred;
tsk->cred = NULL;
- validate_creds(cred);
- alter_cred_subscribers(cred, -1);
- put_cred(cred);
+
+ if (real_cred == cred) {
+ put_cred_many(cred, 2);
+ } else {
+ put_cred(real_cred);
+ put_cred(cred);
+ }
+
+#ifdef CONFIG_KEYS_REQUEST_CACHE
+ key_put(tsk->cached_requested_key);
+ tsk->cached_requested_key = NULL;
+#endif
}
/**
if (!new)
return NULL;
- atomic_set(&new->usage, 1);
-#ifdef CONFIG_DEBUG_CREDENTIALS
- new->magic = CRED_MAGIC;
-#endif
-
- if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
+ atomic_long_set(&new->usage, 1);
+ if (security_cred_alloc_blank(new, GFP_KERNEL_ACCOUNT) < 0)
goto error;
return new;
const struct cred *old;
struct cred *new;
- validate_process_creds();
-
new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
if (!new)
return NULL;
old = task->cred;
memcpy(new, old, sizeof(struct cred));
- atomic_set(&new->usage, 1);
- set_cred_subscribers(new, 0);
+ new->non_rcu = 0;
+ atomic_long_set(&new->usage, 1);
get_group_info(new->group_info);
get_uid(new->user);
get_user_ns(new->user_ns);
new->security = NULL;
#endif
- if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
+ new->ucounts = get_ucounts(new->ucounts);
+ if (!new->ucounts)
+ goto error;
+
+ if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
goto error;
- validate_creds(new);
+
return new;
error:
new->process_keyring = NULL;
#endif
+ new->suid = new->fsuid = new->euid;
+ new->sgid = new->fsgid = new->egid;
+
return new;
}
struct cred *new;
int ret;
+#ifdef CONFIG_KEYS_REQUEST_CACHE
+ p->cached_requested_key = NULL;
+#endif
+
if (
#ifdef CONFIG_KEYS
!p->cred->thread_keyring &&
#endif
clone_flags & CLONE_THREAD
) {
- p->real_cred = get_cred(p->cred);
- get_cred(p->cred);
- alter_cred_subscribers(p->cred, 2);
- kdebug("share_creds(%p{%d,%d})",
- p->cred, atomic_read(&p->cred->usage),
- read_cred_subscribers(p->cred));
- atomic_inc(&p->cred->user->processes);
+ p->real_cred = get_cred_many(p->cred, 2);
+ kdebug("share_creds(%p{%ld})",
+ p->cred, atomic_long_read(&p->cred->usage));
+ inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
return 0;
}
ret = create_user_ns(new);
if (ret < 0)
goto error_put;
+ ret = set_cred_ucounts(new);
+ if (ret < 0)
+ goto error_put;
}
#ifdef CONFIG_KEYS
}
#endif
- atomic_inc(&new->user->processes);
p->cred = p->real_cred = get_cred(new);
- alter_cred_subscribers(new, 2);
- validate_creds(new);
+ inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
return 0;
error_put:
struct task_struct *task = current;
const struct cred *old = task->real_cred;
- kdebug("commit_creds(%p{%d,%d})", new,
- atomic_read(&new->usage),
- read_cred_subscribers(new));
+ kdebug("commit_creds(%p{%ld})", new,
+ atomic_long_read(&new->usage));
BUG_ON(task->cred != old);
-#ifdef CONFIG_DEBUG_CREDENTIALS
- BUG_ON(read_cred_subscribers(old) < 2);
- validate_creds(old);
- validate_creds(new);
-#endif
- BUG_ON(atomic_read(&new->usage) < 1);
+ BUG_ON(atomic_long_read(&new->usage) < 1);
get_cred(new); /* we will require a ref for the subj creds too */
if (task->mm)
set_dumpable(task->mm, suid_dumpable);
task->pdeath_signal = 0;
+ /*
+ * If a task drops privileges and becomes nondumpable,
+ * the dumpability change must become visible before
+ * the credential change; otherwise, a __ptrace_may_access()
+ * racing with this change may be able to attach to a task it
+ * shouldn't be able to attach to (as if the task had dropped
+ * 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(task);
+ key_fsuid_changed(new);
if (!gid_eq(new->fsgid, old->fsgid))
- key_fsgid_changed(task);
+ 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);
+ if (new->user != old->user || new->user_ns != old->user_ns)
+ inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1);
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);
+ if (new->user != old->user || new->user_ns != old->user_ns)
+ dec_rlimit_ucounts(old->ucounts, UCOUNT_RLIMIT_NPROC, 1);
/* send notifications */
if (!uid_eq(new->uid, old->uid) ||
proc_id_connector(task, PROC_EVENT_GID);
/* release the old obj and subj refs both */
- put_cred(old);
- put_cred(old);
+ put_cred_many(old, 2);
return 0;
}
EXPORT_SYMBOL(commit_creds);
*/
void abort_creds(struct cred *new)
{
- kdebug("abort_creds(%p{%d,%d})", new,
- atomic_read(&new->usage),
- read_cred_subscribers(new));
+ kdebug("abort_creds(%p{%ld})", new,
+ atomic_long_read(&new->usage));
-#ifdef CONFIG_DEBUG_CREDENTIALS
- BUG_ON(read_cred_subscribers(new) != 0);
-#endif
- BUG_ON(atomic_read(&new->usage) < 1);
+ BUG_ON(atomic_long_read(&new->usage) < 1);
put_cred(new);
}
EXPORT_SYMBOL(abort_creds);
{
const struct cred *old = current->cred;
- kdebug("override_creds(%p{%d,%d})", new,
- atomic_read(&new->usage),
- read_cred_subscribers(new));
+ kdebug("override_creds(%p{%ld})", new,
+ atomic_long_read(&new->usage));
- validate_creds(old);
- validate_creds(new);
- get_cred(new);
- alter_cred_subscribers(new, 1);
+ /*
+ * NOTE! This uses 'get_new_cred()' rather than 'get_cred()'.
+ *
+ * That means that we do not clear the 'non_rcu' flag, since
+ * we are only installing the cred into the thread-synchronous
+ * '->cred' pointer, not the '->real_cred' pointer that is
+ * visible to other threads under RCU.
+ */
+ get_new_cred((struct cred *)new);
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));
+ kdebug("override_creds() = %p{%ld}", old,
+ atomic_long_read(&old->usage));
return old;
}
EXPORT_SYMBOL(override_creds);
{
const struct cred *override = current->cred;
- kdebug("revert_creds(%p{%d,%d})", old,
- atomic_read(&old->usage),
- read_cred_subscribers(old));
+ kdebug("revert_creds(%p{%ld})", old,
+ atomic_long_read(&old->usage));
- 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);
}
EXPORT_SYMBOL(cred_fscmp);
+int set_cred_ucounts(struct cred *new)
+{
+ struct ucounts *new_ucounts, *old_ucounts = new->ucounts;
+
+ /*
+ * This optimization is needed because alloc_ucounts() uses locks
+ * for table lookups.
+ */
+ if (old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->uid))
+ return 0;
+
+ if (!(new_ucounts = alloc_ucounts(new->user_ns, new->uid)))
+ return -EAGAIN;
+
+ new->ucounts = new_ucounts;
+ put_ucounts(old_ucounts);
+
+ return 0;
+}
+
/*
* 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);
+ cred_jar = KMEM_CACHE(cred,
+ SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
}
/**
* 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.
+ * @daemon is used to provide a base cred, with the security data derived from
+ * that; if this is "&init_task", they'll be set to 0, 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;
+ if (WARN_ON_ONCE(!daemon))
+ return NULL;
+
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);
+ old = get_task_cred(daemon);
*new = *old;
- atomic_set(&new->usage, 1);
- set_cred_subscribers(new, 0);
+ new->non_rcu = 0;
+ atomic_long_set(&new->usage, 1);
get_uid(new->user);
get_user_ns(new->user_ns);
get_group_info(new->group_info);
#ifdef CONFIG_SECURITY
new->security = NULL;
#endif
- if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
+ new->ucounts = get_ucounts(new->ucounts);
+ if (!new->ucounts)
+ goto error;
+
+ if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
goto error;
put_cred(old);
- validate_creds(new);
return new;
error:
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 */
git.samba.org / sfrench / cifs-2.6.git / blobdiff