From d7ccdaa17aab12a49f5e9e327b55167c4af26bf8 Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Fri, 30 Aug 2013 15:37:54 +0100
Subject: [PATCH 1/2] KEYS: Implement a big key type that can save to tmpfs
Implement a big key type that can save its contents to tmpfs and thus
swapspace when memory is tight. This is useful for Kerberos ticket caches.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Simo Sorce <simo@redhat.com>
---
include/keys/big_key-type.h | 25 ++++++
include/linux/key.h | 1 +
security/keys/Kconfig | 11 +++
security/keys/Makefile | 1 +
security/keys/big_key.c | 204 ++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 242 insertions(+)
create mode 100644 include/keys/big_key-type.h
create mode 100644 security/keys/big_key.c
diff --git a/include/keys/big_key-type.h b/include/keys/big_key-type.h
new file mode 100644
index 0000000..d69bc8a
--- /dev/null
+++ b/include/keys/big_key-type.h
@@ -0,0 +1,25 @@
+/* Big capacity key type.
+ *
+ * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.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.
+ */
+
+#ifndef _KEYS_BIG_KEY_TYPE_H
+#define _KEYS_BIG_KEY_TYPE_H
+
+#include <linux/key-type.h>
+
+extern struct key_type key_type_big_key;
+
+extern int big_key_instantiate(struct key *key, struct key_preparsed_payload *prep);
+extern void big_key_revoke(struct key *key);
+extern void big_key_destroy(struct key *key);
+extern void big_key_describe(const struct key *big_key, struct seq_file *m);
+extern long big_key_read(const struct key *key, char __user *buffer, size_t buflen);
+
+#endif /* _KEYS_BIG_KEY_TYPE_H */
diff --git a/include/linux/key.h b/include/linux/key.h
index 2417f78..010dbb6 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -201,6 +201,7 @@ struct key {
unsigned long value;
void __rcu *rcudata;
void *data;
+ void *data2[2];
} payload;
struct assoc_array keys;
};
diff --git a/security/keys/Kconfig b/security/keys/Kconfig
index 15e0dfe..b563622 100644
--- a/security/keys/Kconfig
+++ b/security/keys/Kconfig
@@ -20,6 +20,17 @@ config KEYS
If you are unsure as to whether this is required, answer N.
+config BIG_KEYS
+ tristate "Large payload keys"
+ depends on KEYS
+ depends on TMPFS
+ help
+ This option provides support for holding large keys within the kernel
+ (for example Kerberos ticket caches). The data may be stored out to
+ swapspace by tmpfs.
+
+ If you are unsure as to whether this is required, answer N.
+
config TRUSTED_KEYS
tristate "TRUSTED KEYS"
depends on KEYS && TCG_TPM
diff --git a/security/keys/Makefile b/security/keys/Makefile
index 504aaa0..c487c77 100644
--- a/security/keys/Makefile
+++ b/security/keys/Makefile
@@ -22,5 +22,6 @@ obj-$(CONFIG_SYSCTL) += sysctl.o
#
# Key types
#
+obj-$(CONFIG_BIG_KEYS) += big_key.o
obj-$(CONFIG_TRUSTED_KEYS) += trusted.o
obj-$(CONFIG_ENCRYPTED_KEYS) += encrypted-keys/
diff --git a/security/keys/big_key.c b/security/keys/big_key.c
new file mode 100644
index 0000000..5f9defc
--- /dev/null
+++ b/security/keys/big_key.c
@@ -0,0 +1,204 @@
+/* Large capacity key type
+ *
+ * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/seq_file.h>
+#include <linux/file.h>
+#include <linux/shmem_fs.h>
+#include <linux/err.h>
+#include <keys/user-type.h>
+#include <keys/big_key-type.h>
+
+MODULE_LICENSE("GPL");
+
+/*
+ * If the data is under this limit, there's no point creating a shm file to
+ * hold it as the permanently resident metadata for the shmem fs will be at
+ * least as large as the data.
+ */
+#define BIG_KEY_FILE_THRESHOLD (sizeof(struct inode) + sizeof(struct dentry))
+
+/*
+ * big_key defined keys take an arbitrary string as the description and an
+ * arbitrary blob of data as the payload
+ */
+struct key_type key_type_big_key = {
+ .name = "big_key",
+ .def_lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
+ .instantiate = big_key_instantiate,
+ .match = user_match,
+ .revoke = big_key_revoke,
+ .destroy = big_key_destroy,
+ .describe = big_key_describe,
+ .read = big_key_read,
+};
+
+/*
+ * Instantiate a big key
+ */
+int big_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
+{
+ struct path *path = (struct path *)&key->payload.data2;
+ struct file *file;
+ ssize_t written;
+ size_t datalen = prep->datalen;
+ int ret;
+
+ ret = -EINVAL;
+ if (datalen <= 0 || datalen > 1024 * 1024 || !prep->data)
+ goto error;
+
+ /* Set an arbitrary quota */
+ ret = key_payload_reserve(key, 16);
+ if (ret < 0)
+ goto error;
+
+ key->type_data.x[1] = datalen;
+
+ if (datalen > BIG_KEY_FILE_THRESHOLD) {
+ /* Create a shmem file to store the data in. This will permit the data
+ * to be swapped out if needed.
+ *
+ * TODO: Encrypt the stored data with a temporary key.
+ */
+ file = shmem_file_setup("", datalen, 0);
+ if (IS_ERR(file))
+ goto err_quota;
+
+ written = kernel_write(file, prep->data, prep->datalen, 0);
+ if (written != datalen) {
+ if (written >= 0)
+ ret = -ENOMEM;
+ goto err_fput;
+ }
+
+ /* Pin the mount and dentry to the key so that we can open it again
+ * later
+ */
+ *path = file->f_path;
+ path_get(path);
+ fput(file);
+ } else {
+ /* Just store the data in a buffer */
+ void *data = kmalloc(datalen, GFP_KERNEL);
+ if (!data) {
+ ret = -ENOMEM;
+ goto err_quota;
+ }
+
+ key->payload.data = memcpy(data, prep->data, prep->datalen);
+ }
+ return 0;
+
+err_fput:
+ fput(file);
+err_quota:
+ key_payload_reserve(key, 0);
+error:
+ return ret;
+}
+
+/*
+ * dispose of the links from a revoked keyring
+ * - called with the key sem write-locked
+ */
+void big_key_revoke(struct key *key)
+{
+ struct path *path = (struct path *)&key->payload.data2;
+
+ /* clear the quota */
+ key_payload_reserve(key, 0);
+ if (key_is_instantiated(key) && key->type_data.x[1] > BIG_KEY_FILE_THRESHOLD)
+ vfs_truncate(path, 0);
+}
+
+/*
+ * dispose of the data dangling from the corpse of a big_key key
+ */
+void big_key_destroy(struct key *key)
+{
+ if (key->type_data.x[1] > BIG_KEY_FILE_THRESHOLD) {
+ struct path *path = (struct path *)&key->payload.data2;
+ path_put(path);
+ path->mnt = NULL;
+ path->dentry = NULL;
+ } else {
+ kfree(key->payload.data);
+ key->payload.data = NULL;
+ }
+}
+
+/*
+ * describe the big_key key
+ */
+void big_key_describe(const struct key *key, struct seq_file *m)
+{
+ unsigned long datalen = key->type_data.x[1];
+
+ seq_puts(m, key->description);
+
+ if (key_is_instantiated(key))
+ seq_printf(m, ": %lu [%s]",
+ datalen,
+ datalen > BIG_KEY_FILE_THRESHOLD ? "file" : "buff");
+}
+
+/*
+ * read the key data
+ * - the key's semaphore is read-locked
+ */
+long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
+{
+ unsigned long datalen = key->type_data.x[1];
+ long ret;
+
+ if (!buffer || buflen < datalen)
+ return datalen;
+
+ if (datalen > BIG_KEY_FILE_THRESHOLD) {
+ struct path *path = (struct path *)&key->payload.data2;
+ struct file *file;
+ loff_t pos;
+
+ file = dentry_open(path, O_RDONLY, current_cred());
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+
+ pos = 0;
+ ret = vfs_read(file, buffer, datalen, &pos);
+ fput(file);
+ if (ret >= 0 && ret != datalen)
+ ret = -EIO;
+ } else {
+ ret = datalen;
+ if (copy_to_user(buffer, key->payload.data, datalen) != 0)
+ ret = -EFAULT;
+ }
+
+ return ret;
+}
+
+/*
+ * Module stuff
+ */
+static int __init big_key_init(void)
+{
+ return register_key_type(&key_type_big_key);
+}
+
+static void __exit big_key_cleanup(void)
+{
+ unregister_key_type(&key_type_big_key);
+}
+
+module_init(big_key_init);
+module_exit(big_key_cleanup);
--
1.8.3.1
From 862e98313b10123fa4352117b0b0c0f5a530cefb Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Fri, 30 Aug 2013 15:37:54 +0100
Subject: [PATCH 2/2] KEYS: Add per-user_namespace registers for persistent
per-UID kerberos caches
Add support for per-user_namespace registers of persistent per-UID kerberos
caches held within the kernel.
This allows the kerberos cache to be retained beyond the life of all a user's
processes so that the user's cron jobs can work.
The kerberos cache is envisioned as a keyring/key tree looking something like:
struct user_namespace
\___ .krb_cache keyring - The register
\___ _krb.0 keyring - Root's Kerberos cache
\___ _krb.5000 keyring - User 5000's Kerberos cache
\___ _krb.5001 keyring - User 5001's Kerberos cache
\___ tkt785 big_key - A ccache blob
\___ tkt12345 big_key - Another ccache blob
Or possibly:
struct user_namespace
\___ .krb_cache keyring - The register
\___ _krb.0 keyring - Root's Kerberos cache
\___ _krb.5000 keyring - User 5000's Kerberos cache
\___ _krb.5001 keyring - User 5001's Kerberos cache
\___ tkt785 keyring - A ccache
\___ krbtgt/REDHAT.COM@REDHAT.COM big_key
\___ http/REDHAT.COM@REDHAT.COM user
\___ afs/REDHAT.COM@REDHAT.COM user
\___ nfs/REDHAT.COM@REDHAT.COM user
\___ krbtgt/KERNEL.ORG@KERNEL.ORG big_key
\___ http/KERNEL.ORG@KERNEL.ORG big_key
What goes into a particular Kerberos cache is entirely up to userspace. Kernel
support is limited to giving you the Kerberos cache keyring that you want.
The user asks for their Kerberos cache by:
krb_cache = keyctl_get_krbcache(uid, dest_keyring);
The uid is -1 or the user's own UID for the user's own cache or the uid of some
other user's cache (requires CAP_SETUID). This permits rpc.gssd or whatever to
mess with the cache.
The cache returned is a keyring named "_krb.<uid>" that the possessor can read,
search, clear, invalidate, unlink from and add links to. Active LSMs get a
chance to rule on whether the caller is permitted to make a link.
Each uid's cache keyring is created when it first accessed and is given a
timeout that is extended each time this function is called so that the keyring
goes away after a while. The timeout is configurable by sysctl but defaults to
three days.
Each user_namespace struct gets a lazily-created keyring that serves as the
register. The cache keyrings are added to it. This means that standard key
search and garbage collection facilities are available.
The user_namespace struct's register goes away when it does and anything left
in it is then automatically gc'd.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Simo Sorce <simo@redhat.com>
cc: Serge E. Hallyn <serge.hallyn@ubuntu.com>
cc: Eric W. Biederman <ebiederm@xmission.com>
---
include/linux/user_namespace.h | 7 ++
include/uapi/linux/keyctl.h | 1 +
kernel/user.c | 4 +
kernel/user_namespace.c | 6 ++
security/keys/Kconfig | 17 +++++
security/keys/Makefile | 1 +
security/keys/compat.c | 3 +
security/keys/internal.h | 9 +++
security/keys/keyctl.c | 3 +
security/keys/persistent.c | 169 +++++++++++++++++++++++++++++++++++++++++
security/keys/sysctl.c | 11 +++
11 files changed, 231 insertions(+)
create mode 100644 security/keys/persistent.c
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 4db2985..bb0639d 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -27,6 +27,13 @@ struct user_namespace {
kuid_t owner;
kgid_t group;
unsigned int proc_inum;
+
+ /* Register of per-UID persistent keyrings for this namespace */
+#ifdef CONFIG_PERSISTENT_KEYRINGS
+ struct key *persistent_keyring_register;
+ struct rw_semaphore persistent_keyring_register_sem;
+#endif
+
};
extern struct user_namespace init_user_ns;
diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h
index c9b7f4fa..840cb99 100644
--- a/include/uapi/linux/keyctl.h
+++ b/include/uapi/linux/keyctl.h
@@ -56,5 +56,6 @@
#define KEYCTL_REJECT 19 /* reject a partially constructed key */
#define KEYCTL_INSTANTIATE_IOV 20 /* instantiate a partially constructed key */
#define KEYCTL_INVALIDATE 21 /* invalidate a key */
+#define KEYCTL_GET_PERSISTENT 22 /* get a user's persistent keyring */
#endif /* _LINUX_KEYCTL_H */
diff --git a/kernel/user.c b/kernel/user.c
index 5bbb919..a3a0dbf 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -51,6 +51,10 @@ struct user_namespace init_user_ns = {
.owner = GLOBAL_ROOT_UID,
.group = GLOBAL_ROOT_GID,
.proc_inum = PROC_USER_INIT_INO,
+#ifdef CONFIG_KEYS_KERBEROS_CACHE
+ .krb_cache_register_sem =
+ __RWSEM_INITIALIZER(init_user_ns.krb_cache_register_sem),
+#endif
};
EXPORT_SYMBOL_GPL(init_user_ns);
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 13fb113..2dbc299 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -101,6 +101,9 @@ int create_user_ns(struct cred *new)
set_cred_user_ns(new, ns);
+#ifdef CONFIG_PERSISTENT_KEYRINGS
+ init_rwsem(&ns->persistent_keyring_register_sem);
+#endif
return 0;
}
@@ -130,6 +133,9 @@ void free_user_ns(struct user_namespace *ns)
do {
parent = ns->parent;
+#ifdef CONFIG_PERSISTENT_KEYRINGS
+ key_put(ns->persistent_keyring_register);
+#endif
proc_free_inum(ns->proc_inum);
kmem_cache_free(user_ns_cachep, ns);
ns = parent;
diff --git a/security/keys/Kconfig b/security/keys/Kconfig
index b563622..53d8748 100644
--- a/security/keys/Kconfig
+++ b/security/keys/Kconfig
@@ -20,6 +20,23 @@ config KEYS
If you are unsure as to whether this is required, answer N.
+config PERSISTENT_KEYRINGS
+ bool "Enable register of persistent per-UID keyrings"
+ depends on KEYS
+ help
+ This option provides a register of persistent per-UID keyrings,
+ primarily aimed at Kerberos key storage. The keyrings are persistent
+ in the sense that they stay around after all processes of that UID
+ have exited, not that they survive the machine being rebooted.
+
+ A particular keyring may be accessed by either the user whose keyring
+ it is or by a process with administrative privileges. The active
+ LSMs gets to rule on which admin-level processes get to access the
+ cache.
+
+ Keyrings are created and added into the register upon demand and get
+ removed if they expire (a default timeout is set upon creation).
+
config BIG_KEYS
tristate "Large payload keys"
depends on KEYS
diff --git a/security/keys/Makefile b/security/keys/Makefile
index c487c77..dfb3a7b 100644
--- a/security/keys/Makefile
+++ b/security/keys/Makefile
@@ -18,6 +18,7 @@ obj-y := \
obj-$(CONFIG_KEYS_COMPAT) += compat.o
obj-$(CONFIG_PROC_FS) += proc.o
obj-$(CONFIG_SYSCTL) += sysctl.o
+obj-$(CONFIG_PERSISTENT_KEYRINGS) += persistent.o
#
# Key types
diff --git a/security/keys/compat.c b/security/keys/compat.c
index d65fa7f..bbd32c7 100644
--- a/security/keys/compat.c
+++ b/security/keys/compat.c
@@ -138,6 +138,9 @@ asmlinkage long compat_sys_keyctl(u32 option,
case KEYCTL_INVALIDATE:
return keyctl_invalidate_key(arg2);
+ case KEYCTL_GET_PERSISTENT:
+ return keyctl_get_persistent(arg2, arg3);
+
default:
return -EOPNOTSUPP;
}
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 581c6f6..80b2aac 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -255,6 +255,15 @@ extern long keyctl_invalidate_key(key_serial_t);
extern long keyctl_instantiate_key_common(key_serial_t,
const struct iovec *,
unsigned, size_t, key_serial_t);
+#ifdef CONFIG_PERSISTENT_KEYRINGS
+extern long keyctl_get_persistent(uid_t, key_serial_t);
+extern unsigned persistent_keyring_expiry;
+#else
+static inline long keyctl_get_persistent(uid_t uid, key_serial_t destring)
+{
+ return -EOPNOTSUPP;
+}
+#endif
/*
* Debugging key validation
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 33cfd27..cee72ce 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1667,6 +1667,9 @@ SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
case KEYCTL_INVALIDATE:
return keyctl_invalidate_key((key_serial_t) arg2);
+ case KEYCTL_GET_PERSISTENT:
+ return keyctl_get_persistent((uid_t)arg2, (key_serial_t)arg3);
+
default:
return -EOPNOTSUPP;
}
diff --git a/security/keys/persistent.c b/security/keys/persistent.c
new file mode 100644
index 0000000..631a022
--- /dev/null
+++ b/security/keys/persistent.c
@@ -0,0 +1,169 @@
+/* General persistent per-UID keyrings register
+ *
+ * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/user_namespace.h>
+#include "internal.h"
+
+unsigned persistent_keyring_expiry = 3 * 24 * 3600; /* Expire after 3 days of non-use */
+
+/*
+ * Create the persistent keyring register for the current user namespace.
+ *
+ * Called with the namespace's sem locked for writing.
+ */
+static int key_create_persistent_register(struct user_namespace *ns)
+{
+ struct key *reg = keyring_alloc(".persistent_register",
+ KUIDT_INIT(0), KGIDT_INIT(0),
+ current_cred(),
+ ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW | KEY_USR_READ),
+ KEY_ALLOC_NOT_IN_QUOTA, NULL);
+ if (IS_ERR(reg))
+ return PTR_ERR(reg);
+
+ ns->persistent_keyring_register = reg;
+ return 0;
+}
+
+/*
+ * Create the persistent keyring for the specified user.
+ *
+ * Called with the namespace's sem locked for writing.
+ */
+static key_ref_t key_create_persistent(struct user_namespace *ns, kuid_t uid,
+ struct keyring_index_key *index_key)
+{
+ struct key *persistent;
+ key_ref_t reg_ref, persistent_ref;
+
+ if (!ns->persistent_keyring_register) {
+ long err = key_create_persistent_register(ns);
+ if (err < 0)
+ return ERR_PTR(err);
+ } else {
+ reg_ref = make_key_ref(ns->persistent_keyring_register, true);
+ persistent_ref = find_key_to_update(reg_ref, index_key);
+ if (persistent_ref)
+ return persistent_ref;
+ }
+
+ persistent = keyring_alloc(index_key->description,
+ uid, INVALID_GID, current_cred(),
+ ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW | KEY_USR_READ),
+ KEY_ALLOC_NOT_IN_QUOTA,
+ ns->persistent_keyring_register);
+ if (IS_ERR(persistent))
+ return ERR_CAST(persistent);
+
+ return make_key_ref(persistent, true);
+}
+
+/*
+ * Get the persistent keyring for a specific UID and link it to the nominated
+ * keyring.
+ */
+static long key_get_persistent(struct user_namespace *ns, kuid_t uid,
+ key_ref_t dest_ref)
+{
+ struct keyring_index_key index_key;
+ struct key *persistent;
+ key_ref_t reg_ref, persistent_ref;
+ char buf[32];
+ long ret;
+
+ /* Look in the register if it exists */
+ index_key.type = &key_type_keyring;
+ index_key.description = buf;
+ index_key.desc_len = sprintf(buf, "_persistent.%u", from_kuid(ns, uid));
+
+ if (ns->persistent_keyring_register) {
+ reg_ref = make_key_ref(ns->persistent_keyring_register, true);
+ down_read(&ns->persistent_keyring_register_sem);
+ persistent_ref = find_key_to_update(reg_ref, &index_key);
+ up_read(&ns->persistent_keyring_register_sem);
+
+ if (persistent_ref)
+ goto found;
+ }
+
+ /* It wasn't in the register, so we'll need to create it. We might
+ * also need to create the register.
+ */
+ down_write(&ns->persistent_keyring_register_sem);
+ persistent_ref = key_create_persistent(ns, uid, &index_key);
+ up_write(&ns->persistent_keyring_register_sem);
+ if (!IS_ERR(persistent_ref))
+ goto found;
+
+ return PTR_ERR(persistent_ref);
+
+found:
+ ret = key_task_permission(persistent_ref, current_cred(), KEY_LINK);
+ if (ret == 0) {
+ persistent = key_ref_to_ptr(persistent_ref);
+ ret = key_link(key_ref_to_ptr(dest_ref), persistent);
+ if (ret == 0) {
+ key_set_timeout(persistent, persistent_keyring_expiry);
+ ret = persistent->serial;
+ }
+ }
+
+ key_ref_put(persistent_ref);
+ return ret;
+}
+
+/*
+ * Get the persistent keyring for a specific UID and link it to the nominated
+ * keyring.
+ */
+long keyctl_get_persistent(uid_t _uid, key_serial_t destid)
+{
+ struct user_namespace *ns = current_user_ns();
+ key_ref_t dest_ref;
+ kuid_t uid;
+ long ret;
+
+ /* -1 indicates the current user */
+ if (_uid == (uid_t)-1) {
+ uid = current_uid();
+ } else {
+ uid = make_kuid(ns, _uid);
+ if (!uid_valid(uid))
+ return -EINVAL;
+
+ /* You can only see your own persistent cache if you're not
+ * sufficiently privileged.
+ */
+ if (!uid_eq(uid, current_uid()) &&
+ /* uid_eq(uid, current_suid()) && */
+ !uid_eq(uid, current_euid()) &&
+ /* uid_eq(uid, current_fsuid()) && */
+ !ns_capable(ns, CAP_SETUID))
+ return -EPERM;
+ }
+
+ /* There must be a destination keyring */
+ dest_ref = lookup_user_key(destid, KEY_LOOKUP_CREATE, KEY_WRITE);
+ if (IS_ERR(dest_ref))
+ return PTR_ERR(dest_ref);
+ if (key_ref_to_ptr(dest_ref)->type != &key_type_keyring) {
+ ret = -ENOTDIR;
+ goto out_put_dest;
+ }
+
+ ret = key_get_persistent(ns, uid, dest_ref);
+
+out_put_dest:
+ key_ref_put(dest_ref);
+ return ret;
+}
diff --git a/security/keys/sysctl.c b/security/keys/sysctl.c
index ee32d18..8c0af08 100644
--- a/security/keys/sysctl.c
+++ b/security/keys/sysctl.c
@@ -61,5 +61,16 @@ ctl_table key_sysctls[] = {
.extra1 = (void *) &zero,
.extra2 = (void *) &max,
},
+#ifdef CONFIG_PERSISTENT_KEYRINGS
+ {
+ .procname = "persistent_keyring_expiry",
+ .data = &persistent_keyring_expiry,
+ .maxlen = sizeof(unsigned),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = (void *) &zero,
+ .extra2 = (void *) &max,
+ },
+#endif
{ }
};
--
1.8.3.1