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Registered in England and Wales under Company Registration No. 3798903 Subject: [RFC PATCH 12/27] containers: Allow a daemon to intercept request_key upcalls in a container From: David Howells To: keyrings@vger.kernel.org, trond.myklebust@hammerspace.com, sfrench@samba.org Cc: linux-security-module@vger.kernel.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, rgb@redhat.com, dhowells@redhat.com, linux-kernel@vger.kernel.org Date: Fri, 15 Feb 2019 16:09:16 +0000 Message-ID: <155024695603.21651.8408384800355761335.stgit@warthog.procyon.org.uk> In-Reply-To: <155024683432.21651.14153938339749694146.stgit@warthog.procyon.org.uk> References: <155024683432.21651.14153938339749694146.stgit@warthog.procyon.org.uk> User-Agent: StGit/unknown-version MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 15 Feb 2019 16:09:19 +0000 (UTC) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Provide a mechanism by which a running daemon can intercept request_key upcalls, filtered by namespace and key type, and service them. The list of active services is per-container. Intercepts for a specific {key_type, namespace} can be installed on a container with: keyctl(KEYCTL_ADD_UPCALL_INTERCEPT, int containerfd, const char *type_name, unsigned int ns_id, key_serial_t dest_keyring); The authentication token keys for intercepted keys are linked into the destination keyring. Signed-off-by: David Howells --- include/linux/container.h | 2 include/linux/key-type.h | 2 include/uapi/linux/keyctl.h | 1 kernel/container.c | 4 + security/keys/Makefile | 2 security/keys/compat.c | 5 + security/keys/container.c | 227 ++++++++++++++++++++++++++++++++++++++ security/keys/internal.h | 10 ++ security/keys/keyctl.c | 14 ++ security/keys/request_key.c | 18 ++- security/keys/request_key_auth.c | 6 + 11 files changed, 278 insertions(+), 13 deletions(-) create mode 100644 security/keys/container.c diff --git a/include/linux/container.h b/include/linux/container.h index 087aa1885ef7..a8cac800ce75 100644 --- a/include/linux/container.h +++ b/include/linux/container.h @@ -42,6 +42,7 @@ struct container { struct list_head members; /* Member processes, guarded with ->lock */ struct list_head child_link; /* Link in parent->children */ struct list_head children; /* Child containers */ + struct list_head req_key_traps; /* Traps for request-key upcalls */ wait_queue_head_t waitq; /* Someone waiting for init to exit waits here */ unsigned long flags; #define CONTAINER_FLAG_INIT_STARTED 0 /* Init is started - certain ops now prohibited */ @@ -60,6 +61,7 @@ extern int copy_container(unsigned long flags, struct task_struct *tsk, struct container *container); extern void exit_container(struct task_struct *tsk); extern void put_container(struct container *c); +extern long key_del_intercept(struct container *c, const char *type); static inline struct container *get_container(struct container *c) { diff --git a/include/linux/key-type.h b/include/linux/key-type.h index 2148a6bf58f1..0e09dac53245 100644 --- a/include/linux/key-type.h +++ b/include/linux/key-type.h @@ -66,7 +66,7 @@ struct key_match_data { */ struct key_type { /* name of the type */ - const char *name; + const char name[24]; /* default payload length for quota precalculation (optional) * - this can be used instead of calling key_payload_reserve(), that diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h index e9e7da849619..85e8fef89bba 100644 --- a/include/uapi/linux/keyctl.h +++ b/include/uapi/linux/keyctl.h @@ -68,6 +68,7 @@ #define KEYCTL_PKEY_VERIFY 28 /* Verify a public key signature */ #define KEYCTL_RESTRICT_KEYRING 29 /* Restrict keys allowed to link to a keyring */ #define KEYCTL_WATCH_KEY 30 /* Watch a key or ring of keys for changes */ +#define KEYCTL_CONTAINER_INTERCEPT 31 /* Intercept upcalls inside a container */ /* keyctl structures */ struct keyctl_dh_params { diff --git a/kernel/container.c b/kernel/container.c index 360284db959b..33e41fe5050b 100644 --- a/kernel/container.c +++ b/kernel/container.c @@ -35,6 +35,7 @@ struct container init_container = { .members.next = &init_task.container_link, .members.prev = &init_task.container_link, .children = LIST_HEAD_INIT(init_container.children), + .req_key_traps = LIST_HEAD_INIT(init_container.req_key_traps), .flags = (1 << CONTAINER_FLAG_INIT_STARTED), .lock = __SPIN_LOCK_UNLOCKED(init_container.lock), .seq = SEQCNT_ZERO(init_fs.seq), @@ -53,6 +54,8 @@ void put_container(struct container *c) while (c && refcount_dec_and_test(&c->usage)) { BUG_ON(!list_empty(&c->members)); + if (!list_empty(&c->req_key_traps)) + key_del_intercept(c, NULL); if (c->pid_ns) put_pid_ns(c->pid_ns); if (c->ns) @@ -286,6 +289,7 @@ static struct container *alloc_container(const char __user *name) INIT_LIST_HEAD(&c->members); INIT_LIST_HEAD(&c->children); + INIT_LIST_HEAD(&c->req_key_traps); init_waitqueue_head(&c->waitq); spin_lock_init(&c->lock); refcount_set(&c->usage, 1); diff --git a/security/keys/Makefile b/security/keys/Makefile index 9cef54064f60..24f5df27b1c2 100644 --- a/security/keys/Makefile +++ b/security/keys/Makefile @@ -16,6 +16,7 @@ obj-y := \ request_key.o \ request_key_auth.o \ user_defined.o + compat-obj-$(CONFIG_KEY_DH_OPERATIONS) += compat_dh.o obj-$(CONFIG_KEYS_COMPAT) += compat.o $(compat-obj-y) obj-$(CONFIG_PROC_FS) += proc.o @@ -23,6 +24,7 @@ obj-$(CONFIG_SYSCTL) += sysctl.o obj-$(CONFIG_PERSISTENT_KEYRINGS) += persistent.o obj-$(CONFIG_KEY_DH_OPERATIONS) += dh.o obj-$(CONFIG_ASYMMETRIC_KEY_TYPE) += keyctl_pkey.o +obj-$(CONFIG_CONTAINERS) += container.o # # Key types diff --git a/security/keys/compat.c b/security/keys/compat.c index 021d8e1c9233..6420881e5ce7 100644 --- a/security/keys/compat.c +++ b/security/keys/compat.c @@ -161,6 +161,11 @@ COMPAT_SYSCALL_DEFINE5(keyctl, u32, option, case KEYCTL_WATCH_KEY: return keyctl_watch_key(arg2, arg3, arg4); +#ifdef CONFIG_CONTAINERS + case KEYCTL_CONTAINER_INTERCEPT: + return keyctl_container_intercept(arg2, compat_ptr(arg3), arg4, arg5); +#endif + default: return -EOPNOTSUPP; } diff --git a/security/keys/container.c b/security/keys/container.c new file mode 100644 index 000000000000..c61c43658f3b --- /dev/null +++ b/security/keys/container.c @@ -0,0 +1,227 @@ +/* Container intercept interface + * + * Copyright (C) 2019 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 +#include +#include +#include +#include +#include +#include +#include "internal.h" + +struct request_key_intercept { + char type[32]; /* The type of key to be trapped */ + struct list_head link; /* Link in containers->req_key_traps */ + struct key *dest_keyring; /* Where to place the trapped auth keys */ + struct ns_common *ns; /* Namespace the key must match */ +}; + +/* + * Add an intercept filter to a container. + */ +static long key_add_intercept(struct container *c, struct request_key_intercept *rki) +{ + struct request_key_intercept *p; + + kenter("%p,{%s,%d}", c, rki->type, key_serial(rki->dest_keyring)); + + spin_lock(&c->lock); + list_for_each_entry(p, &c->req_key_traps, link) { + if (strcmp(rki->type, p->type) == 0) { + spin_unlock(&c->lock); + return -EEXIST; + } + } + + /* We put all-matching rules at the back so they're checked after the + * more specific rules. + */ + if (rki->type[0] == '*' && !rki->type[1]) + list_add_tail(&rki->link, &c->req_key_traps); + else + list_add(&rki->link, &c->req_key_traps); + + spin_unlock(&c->lock); + kleave(" = 0"); + return 0; +} + +/* + * Remove one or more intercept filters from a container. Returns the number + * of entries removed. + */ +long key_del_intercept(struct container *c, const char *type) +{ + struct request_key_intercept *p, *q; + long count; + LIST_HEAD(graveyard); + + kenter("%p,%s", c, type); + + spin_lock(&c->lock); + list_for_each_entry_safe(p, q, &c->req_key_traps, link) { + if (!type || strcmp(p->type, type) == 0) { + kdebug("- match %d", key_serial(p->dest_keyring)); + list_move(&p->link, &graveyard); + } + } + spin_unlock(&c->lock); + + count = 0; + while (!list_empty(&graveyard)) { + p = list_entry(graveyard.next, struct request_key_intercept, link); + list_del(&p->link); + count++; + + key_put(p->dest_keyring); + kfree(p); + } + + kleave(" = %ld", count); + return count; +} + +/* + * Create an intercept filter and add it to a container. + */ +static long key_create_intercept(struct container *c, const char *type, + key_serial_t dest_ring_id) +{ + struct request_key_intercept *rki; + key_ref_t dest_ref; + long ret = -ENOMEM; + + dest_ref = lookup_user_key(dest_ring_id, KEY_LOOKUP_CREATE, + KEY_NEED_WRITE); + if (IS_ERR(dest_ref)) + return PTR_ERR(dest_ref); + + rki = kzalloc(sizeof(*rki), GFP_KERNEL); + if (!rki) + goto out_dest; + + memcpy(rki->type, type, sizeof(rki->type)); + rki->dest_keyring = key_ref_to_ptr(dest_ref); + /* TODO: set rki->ns */ + + ret = key_add_intercept(c, rki); + if (ret < 0) + goto out_rki; + return ret; + +out_rki: + kfree(rki); +out_dest: + key_ref_put(dest_ref); + return ret; +} + +/* + * Add or remove (if dest_keyring==0) a request_key upcall intercept trap upon + * a container. If _type points to a string of "*" that matches all types. + */ +long keyctl_container_intercept(int containerfd, + const char *_type, + unsigned int ns_id, + key_serial_t dest_ring_id) +{ + struct container *c; + struct fd f; + char type[32] = ""; + long ret; + + if (containerfd < 0 || ns_id < 0) + return -EINVAL; + if (dest_ring_id && !_type) + return -EINVAL; + + f = fdget(containerfd); + if (!f.file) + return -EBADF; + ret = -EINVAL; + if (!is_container_file(f.file)) + goto out_fd; + + c = f.file->private_data; + + /* Find out what type we're dealing with (can be NULL to make removal + * remove everything). + */ + if (_type) { + ret = key_get_type_from_user(type, _type, sizeof(type)); + if (ret < 0) + goto out_fd; + } + + /* TODO: Get the namespace to filter on */ + + /* We add a filter if a destination keyring has been specified. */ + if (dest_ring_id) { + ret = key_create_intercept(c, type, dest_ring_id); + } else { + ret = key_del_intercept(c, _type ? type : NULL); + } + +out_fd: + fdput(f); + return ret; +} + +/* + * Queue a construction record if we can find a handler. + * + * Returns true if we found a handler - in which case ownership of the + * construction record has been passed on to the service queue and the caller + * can no longer touch it. + */ +int queue_request_key(struct key *authkey) +{ + struct container *c = current->container; + struct request_key_intercept *rki; + struct request_key_auth *rka = get_request_key_auth(authkey); + struct key *service_keyring; + struct key *key = rka->target_key; + int ret; + + kenter("%p,%d,%d", c, key_serial(authkey), key_serial(key)); + + if (list_empty(&c->req_key_traps)) { + kleave(" = -EAGAIN [e]"); + return -EAGAIN; + } + + spin_lock(&c->lock); + + list_for_each_entry(rki, &c->req_key_traps, link) { + if (strcmp(rki->type, "*") == 0 || + strcmp(rki->type, key->type->name) == 0) + goto found_match; + } + + spin_unlock(&c->lock); + kleave(" = -EAGAIN [n]"); + return -EAGAIN; + +found_match: + service_keyring = key_get(rki->dest_keyring); + kdebug("- match %d", key_serial(service_keyring)); + spin_unlock(&c->lock); + + /* We add the authentication key to the keyring for the service daemon + * to collect. This can be detected by means of a watch on the service + * keyring. + */ + ret = key_link(service_keyring, authkey); + key_put(service_keyring); + kleave(" = %d", ret); + return ret; +} diff --git a/security/keys/internal.h b/security/keys/internal.h index 14c5b8ad5bd6..e98fca465146 100644 --- a/security/keys/internal.h +++ b/security/keys/internal.h @@ -93,6 +93,7 @@ extern wait_queue_head_t request_key_conswq; extern void key_set_index_key(struct keyring_index_key *index_key); extern struct key_type *key_type_lookup(const char *type); extern void key_type_put(struct key_type *ktype); +extern int key_get_type_from_user(char *, const char __user *, unsigned); extern int __key_link_begin(struct key *keyring, const struct keyring_index_key *index_key, @@ -180,6 +181,11 @@ extern void key_gc_keytype(struct key_type *ktype); extern int key_task_permission(const key_ref_t key_ref, const struct cred *cred, key_perm_t perm); +#ifdef CONFIG_CONTAINERS +extern int queue_request_key(struct key *); +#else +static inline int queue_request_key(struct key *authkey) { return -EAGAIN; } +#endif static inline void notify_key(struct key *key, enum key_notification_subtype subtype, u32 aux) @@ -354,6 +360,10 @@ static inline long keyctl_watch_key(key_serial_t key_id, int watch_fd, int watch } #endif +#ifdef CONFIG_CONTAINERS +extern long keyctl_container_intercept(int, const char __user *, unsigned int, key_serial_t); +#endif + /* * Debugging key validation */ diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 94b99a52b4e5..38ff33431f33 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -30,9 +30,9 @@ #define KEY_MAX_DESC_SIZE 4096 -static int key_get_type_from_user(char *type, - const char __user *_type, - unsigned len) +int key_get_type_from_user(char *type, + const char __user *_type, + unsigned len) { int ret; @@ -1857,6 +1857,14 @@ SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3, case KEYCTL_WATCH_KEY: return keyctl_watch_key((key_serial_t)arg2, (int)arg3, (int)arg4); +#ifdef CONFIG_CONTAINERS + case KEYCTL_CONTAINER_INTERCEPT: + return keyctl_container_intercept((int)arg2, + (const char __user *)arg3, + (unsigned int)arg4, + (key_serial_t)arg5); +#endif + default: return -EOPNOTSUPP; } diff --git a/security/keys/request_key.c b/security/keys/request_key.c index edfabf20bdbb..078767564283 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include "internal.h" #include @@ -91,11 +92,11 @@ static int call_usermodehelper_keys(const char *path, char **argv, char **envp, * Request userspace finish the construction of a key * - execute "/sbin/request-key " */ -static int call_sbin_request_key(struct key *authkey, void *aux) +static int call_sbin_request_key(struct key *authkey) { static char const request_key[] = "/sbin/request-key"; struct request_key_auth *rka = get_request_key_auth(authkey); - const struct cred *cred = current_cred(); + const struct cred *cred = rka->cred; key_serial_t prkey, sskey; struct key *key = rka->target_key, *keyring, *session; char *argv[9], *envp[3], uid_str[12], gid_str[12]; @@ -203,7 +204,6 @@ static int construct_key(struct key *key, const void *callout_info, size_t callout_len, void *aux, struct key *dest_keyring) { - request_key_actor_t actor; struct key *authkey; int ret; @@ -216,11 +216,13 @@ static int construct_key(struct key *key, const void *callout_info, return PTR_ERR(authkey); /* Make the call */ - actor = call_sbin_request_key; - if (key->type->request_key) - actor = key->type->request_key; - - ret = actor(authkey, aux); + if (key->type->request_key) { + ret = key->type->request_key(authkey, aux); + } else { + ret = queue_request_key(authkey); + if (ret == -EAGAIN) + ret = call_sbin_request_key(authkey); + } /* check that the actor called complete_request_key() prior to * returning an error */ diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c index afc304e8b61e..cd75173cadad 100644 --- a/security/keys/request_key_auth.c +++ b/security/keys/request_key_auth.c @@ -123,6 +123,10 @@ static void free_request_key_auth(struct request_key_auth *rka) { if (!rka) return; + + if (rka->target_key->state == KEY_IS_UNINSTANTIATED) + key_reject_and_link(rka->target_key, 0, -ENOKEY, NULL, NULL); + key_put(rka->target_key); key_put(rka->dest_keyring); if (rka->cred) @@ -184,7 +188,7 @@ struct key *request_key_auth_new(struct key *target, const char *op, goto error_free_rka; } - irka = cred->request_key_auth->payload.data[0]; + irka = get_request_key_auth(cred->request_key_auth); rka->cred = get_cred(irka->cred); rka->pid = irka->pid;