From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- security/keys/user_defined.c | 207 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 207 insertions(+) create mode 100644 security/keys/user_defined.c (limited to 'security/keys/user_defined.c') diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c new file mode 100644 index 000000000..6f88b507f --- /dev/null +++ b/security/keys/user_defined.c @@ -0,0 +1,207 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* user_defined.c: user defined key type + * + * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include +#include +#include +#include +#include "internal.h" + +static int logon_vet_description(const char *desc); + +/* + * user defined keys take an arbitrary string as the description and an + * arbitrary blob of data as the payload + */ +struct key_type key_type_user = { + .name = "user", + .preparse = user_preparse, + .free_preparse = user_free_preparse, + .instantiate = generic_key_instantiate, + .update = user_update, + .revoke = user_revoke, + .destroy = user_destroy, + .describe = user_describe, + .read = user_read, +}; + +EXPORT_SYMBOL_GPL(key_type_user); + +/* + * This key type is essentially the same as key_type_user, but it does + * not define a .read op. This is suitable for storing username and + * password pairs in the keyring that you do not want to be readable + * from userspace. + */ +struct key_type key_type_logon = { + .name = "logon", + .preparse = user_preparse, + .free_preparse = user_free_preparse, + .instantiate = generic_key_instantiate, + .update = user_update, + .revoke = user_revoke, + .destroy = user_destroy, + .describe = user_describe, + .vet_description = logon_vet_description, +}; +EXPORT_SYMBOL_GPL(key_type_logon); + +/* + * Preparse a user defined key payload + */ +int user_preparse(struct key_preparsed_payload *prep) +{ + struct user_key_payload *upayload; + size_t datalen = prep->datalen; + + if (datalen == 0 || datalen > 32767 || !prep->data) + return -EINVAL; + + upayload = kmalloc_flex(*upayload, data, datalen); + if (!upayload) + return -ENOMEM; + + /* attach the data */ + prep->quotalen = datalen; + prep->payload.data[0] = upayload; + upayload->datalen = datalen; + memcpy(upayload->data, prep->data, datalen); + return 0; +} +EXPORT_SYMBOL_GPL(user_preparse); + +/* + * Free a preparse of a user defined key payload + */ +void user_free_preparse(struct key_preparsed_payload *prep) +{ + kfree_sensitive(prep->payload.data[0]); +} +EXPORT_SYMBOL_GPL(user_free_preparse); + +static void user_free_payload_rcu(struct rcu_head *head) +{ + struct user_key_payload *payload; + + payload = container_of(head, struct user_key_payload, rcu); + kfree_sensitive(payload); +} + +/* + * update a user defined key + * - the key's semaphore is write-locked + */ +int user_update(struct key *key, struct key_preparsed_payload *prep) +{ + struct user_key_payload *zap = NULL; + int ret; + + /* check the quota and attach the new data */ + ret = key_payload_reserve(key, prep->datalen); + if (ret < 0) + return ret; + + /* attach the new data, displacing the old */ + key->expiry = prep->expiry; + if (key_is_positive(key)) + zap = dereference_key_locked(key); + rcu_assign_keypointer(key, prep->payload.data[0]); + prep->payload.data[0] = NULL; + + if (zap) + call_rcu(&zap->rcu, user_free_payload_rcu); + return ret; +} +EXPORT_SYMBOL_GPL(user_update); + +/* + * dispose of the links from a revoked keyring + * - called with the key sem write-locked + */ +void user_revoke(struct key *key) +{ + struct user_key_payload *upayload = user_key_payload_locked(key); + + /* clear the quota */ + key_payload_reserve(key, 0); + + if (upayload) { + rcu_assign_keypointer(key, NULL); + call_rcu(&upayload->rcu, user_free_payload_rcu); + } +} + +EXPORT_SYMBOL(user_revoke); + +/* + * dispose of the data dangling from the corpse of a user key + */ +void user_destroy(struct key *key) +{ + struct user_key_payload *upayload = key->payload.data[0]; + + kfree_sensitive(upayload); +} + +EXPORT_SYMBOL_GPL(user_destroy); + +/* + * describe the user key + */ +void user_describe(const struct key *key, struct seq_file *m) +{ + seq_puts(m, key->description); + if (key_is_positive(key)) + seq_printf(m, ": %u", key->datalen); +} + +EXPORT_SYMBOL_GPL(user_describe); + +/* + * read the key data + * - the key's semaphore is read-locked + */ +long user_read(const struct key *key, char *buffer, size_t buflen) +{ + const struct user_key_payload *upayload; + long ret; + + upayload = user_key_payload_locked(key); + ret = upayload->datalen; + + /* we can return the data as is */ + if (buffer && buflen > 0) { + if (buflen > upayload->datalen) + buflen = upayload->datalen; + + memcpy(buffer, upayload->data, buflen); + } + + return ret; +} + +EXPORT_SYMBOL_GPL(user_read); + +/* Vet the description for a "logon" key */ +static int logon_vet_description(const char *desc) +{ + char *p; + + /* require a "qualified" description string */ + p = strchr(desc, ':'); + if (!p) + return -EINVAL; + + /* also reject description with ':' as first char */ + if (p == desc) + return -EINVAL; + + return 0; +} -- cgit v1.3.1