ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faultsgrafted

When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set,
a user fault may trigger show_pte() without any lock.
If another thread in the same process concurrently calls munmap(),
the page table pages may be freed while show_pte() is still traversing
them, causing a use-after-free in show_pte().

If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table
of PMD are freed when show_pte() is running.

Acquire mmap_write_lock() around show_pte() for user faults to fix the
contention.

For user faults, additionally restrict that show_pte() is called only
when the addr is a user-space address (addr < TASK_SIZE). This is because
the lock of tsk->mm only protects the virtual memory of user address space,
furthermore, dumping the page tables of a kernel-space address for user
faults is unnecessary and may have security implications.

Keep everything unchanged for kernel faults, because the kernel is
already in the "oops" state, acquiring a lock may risk a deadlock.

Co-developed-by: Qi Xi <xiqi2@huawei.com>

Fixes: 6d021b724481 ("ARM: dump pgd, pmd and pte states on unhandled data abort faults")
Link: https://lore.kernel.org/20260716014022.2823-1-xieyuanbin1@huawei.com
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Xie Yuanbin <xieyuanbin1@huawei.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 313 insertions, 0 deletions

diff --git a/crypto/aead.c b/crypto/aead.c
new file mode 100644
index 000000000..045b74c37
--- /dev/null
+++ b/crypto/aead.c
@@ -0,0 +1,313 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * AEAD: Authenticated Encryption with Associated Data
+ *
+ * This file provides API support for AEAD algorithms.
+ *
+ * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <crypto/internal/aead.h>
+#include <linux/cryptouser.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <linux/string.h>
+#include <linux/string_choices.h>
+#include <net/netlink.h>
+
+#include "internal.h"
+
+static int setkey_unaligned(struct crypto_aead *tfm, const u8 *key,
+			    unsigned int keylen)
+{
+	unsigned long alignmask = crypto_aead_alignmask(tfm);
+	int ret;
+	u8 *buffer, *alignbuffer;
+	unsigned long absize;
+
+	absize = keylen + alignmask;
+	buffer = kmalloc(absize, GFP_ATOMIC);
+	if (!buffer)
+		return -ENOMEM;
+
+	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
+	memcpy(alignbuffer, key, keylen);
+	ret = crypto_aead_alg(tfm)->setkey(tfm, alignbuffer, keylen);
+	kfree_sensitive(buffer);
+	return ret;
+}
+
+int crypto_aead_setkey(struct crypto_aead *tfm,
+		       const u8 *key, unsigned int keylen)
+{
+	unsigned long alignmask = crypto_aead_alignmask(tfm);
+	int err;
+
+	if ((unsigned long)key & alignmask)
+		err = setkey_unaligned(tfm, key, keylen);
+	else
+		err = crypto_aead_alg(tfm)->setkey(tfm, key, keylen);
+
+	if (unlikely(err)) {
+		crypto_aead_set_flags(tfm, CRYPTO_TFM_NEED_KEY);
+		return err;
+	}
+
+	crypto_aead_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_aead_setkey);
+
+int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
+{
+	int err;
+
+	if ((!authsize && crypto_aead_maxauthsize(tfm)) ||
+	    authsize > crypto_aead_maxauthsize(tfm))
+		return -EINVAL;
+
+	if (crypto_aead_alg(tfm)->setauthsize) {
+		err = crypto_aead_alg(tfm)->setauthsize(tfm, authsize);
+		if (err)
+			return err;
+	}
+
+	tfm->authsize = authsize;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_aead_setauthsize);
+
+int crypto_aead_encrypt(struct aead_request *req)
+{
+	struct crypto_aead *aead = crypto_aead_reqtfm(req);
+
+	if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
+		return -ENOKEY;
+
+	return crypto_aead_alg(aead)->encrypt(req);
+}
+EXPORT_SYMBOL_GPL(crypto_aead_encrypt);
+
+int crypto_aead_decrypt(struct aead_request *req)
+{
+	struct crypto_aead *aead = crypto_aead_reqtfm(req);
+
+	if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
+		return -ENOKEY;
+
+	if (req->cryptlen < crypto_aead_authsize(aead))
+		return -EINVAL;
+
+	return crypto_aead_alg(aead)->decrypt(req);
+}
+EXPORT_SYMBOL_GPL(crypto_aead_decrypt);
+
+static void crypto_aead_exit_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_aead *aead = __crypto_aead_cast(tfm);
+	struct aead_alg *alg = crypto_aead_alg(aead);
+
+	alg->exit(aead);
+}
+
+static int crypto_aead_init_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_aead *aead = __crypto_aead_cast(tfm);
+	struct aead_alg *alg = crypto_aead_alg(aead);
+
+	crypto_aead_set_flags(aead, CRYPTO_TFM_NEED_KEY);
+	crypto_aead_set_reqsize(aead, crypto_tfm_alg_reqsize(tfm));
+
+	aead->authsize = alg->maxauthsize;
+
+	if (alg->exit)
+		aead->base.exit = crypto_aead_exit_tfm;
+
+	if (alg->init)
+		return alg->init(aead);
+
+	return 0;
+}
+
+static int __maybe_unused crypto_aead_report(
+	struct sk_buff *skb, struct crypto_alg *alg)
+{
+	struct aead_alg *aead = container_of(alg, struct aead_alg, base);
+	struct crypto_report_aead raead = {
+		.type = "aead",
+		.geniv = "<none>",
+	};
+
+	raead.blocksize = alg->cra_blocksize;
+	raead.maxauthsize = aead->maxauthsize;
+	raead.ivsize = aead->ivsize;
+
+	return nla_put(skb, CRYPTOCFGA_REPORT_AEAD, sizeof(raead), &raead);
+}
+
+static void __maybe_unused crypto_aead_show(struct seq_file *m,
+					    struct crypto_alg *alg)
+{
+	struct aead_alg *aead = container_of(alg, struct aead_alg, base);
+
+	seq_printf(m, "type         : aead\n");
+	seq_printf(m, "async        : %s\n",
+		   str_yes_no(alg->cra_flags & CRYPTO_ALG_ASYNC));
+	seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
+	seq_printf(m, "ivsize       : %u\n", aead->ivsize);
+	seq_printf(m, "maxauthsize  : %u\n", aead->maxauthsize);
+	seq_printf(m, "geniv        : <none>\n");
+}
+
+static void crypto_aead_free_instance(struct crypto_instance *inst)
+{
+	struct aead_instance *aead = aead_instance(inst);
+
+	aead->free(aead);
+}
+
+static const struct crypto_type crypto_aead_type = {
+	.extsize = crypto_alg_extsize,
+	.init_tfm = crypto_aead_init_tfm,
+	.free = crypto_aead_free_instance,
+#ifdef CONFIG_PROC_FS
+	.show = crypto_aead_show,
+#endif
+#if IS_ENABLED(CONFIG_CRYPTO_USER)
+	.report = crypto_aead_report,
+#endif
+	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
+	.maskset = CRYPTO_ALG_TYPE_MASK,
+	.type = CRYPTO_ALG_TYPE_AEAD,
+	.tfmsize = offsetof(struct crypto_aead, base),
+	.algsize = offsetof(struct aead_alg, base),
+};
+
+int crypto_grab_aead(struct crypto_aead_spawn *spawn,
+		     struct crypto_instance *inst,
+		     const char *name, u32 type, u32 mask)
+{
+	spawn->base.frontend = &crypto_aead_type;
+	return crypto_grab_spawn(&spawn->base, inst, name, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_grab_aead);
+
+struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask)
+{
+	return crypto_alloc_tfm(alg_name, &crypto_aead_type, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_aead);
+
+struct crypto_sync_aead *crypto_alloc_sync_aead(const char *alg_name, u32 type, u32 mask)
+{
+	struct crypto_aead *tfm;
+
+	/* Only sync algorithms are allowed. */
+	mask |= CRYPTO_ALG_ASYNC;
+	type &= ~(CRYPTO_ALG_ASYNC);
+
+	tfm = crypto_alloc_tfm(alg_name, &crypto_aead_type, type, mask);
+
+	if (!IS_ERR(tfm) && WARN_ON(crypto_aead_reqsize(tfm) > MAX_SYNC_AEAD_REQSIZE)) {
+		crypto_free_aead(tfm);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return (struct crypto_sync_aead *)tfm;
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_sync_aead);
+
+int crypto_has_aead(const char *alg_name, u32 type, u32 mask)
+{
+	return crypto_type_has_alg(alg_name, &crypto_aead_type, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_has_aead);
+
+static int aead_prepare_alg(struct aead_alg *alg)
+{
+	struct crypto_alg *base = &alg->base;
+
+	if (max3(alg->maxauthsize, alg->ivsize, alg->chunksize) >
+	    PAGE_SIZE / 8)
+		return -EINVAL;
+
+	if (!alg->chunksize)
+		alg->chunksize = base->cra_blocksize;
+
+	base->cra_type = &crypto_aead_type;
+	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
+	base->cra_flags |= CRYPTO_ALG_TYPE_AEAD;
+
+	return 0;
+}
+
+int crypto_register_aead(struct aead_alg *alg)
+{
+	struct crypto_alg *base = &alg->base;
+	int err;
+
+	err = aead_prepare_alg(alg);
+	if (err)
+		return err;
+
+	return crypto_register_alg(base);
+}
+EXPORT_SYMBOL_GPL(crypto_register_aead);
+
+void crypto_unregister_aead(struct aead_alg *alg)
+{
+	crypto_unregister_alg(&alg->base);
+}
+EXPORT_SYMBOL_GPL(crypto_unregister_aead);
+
+int crypto_register_aeads(struct aead_alg *algs, int count)
+{
+	int i, ret;
+
+	for (i = 0; i < count; i++) {
+		ret = crypto_register_aead(&algs[i]);
+		if (ret)
+			goto err;
+	}
+
+	return 0;
+
+err:
+	for (--i; i >= 0; --i)
+		crypto_unregister_aead(&algs[i]);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(crypto_register_aeads);
+
+void crypto_unregister_aeads(struct aead_alg *algs, int count)
+{
+	int i;
+
+	for (i = count - 1; i >= 0; --i)
+		crypto_unregister_aead(&algs[i]);
+}
+EXPORT_SYMBOL_GPL(crypto_unregister_aeads);
+
+int aead_register_instance(struct crypto_template *tmpl,
+			   struct aead_instance *inst)
+{
+	int err;
+
+	if (WARN_ON(!inst->free))
+		return -EINVAL;
+
+	err = aead_prepare_alg(&inst->alg);
+	if (err)
+		return err;
+
+	return crypto_register_instance(tmpl, aead_crypto_instance(inst));
+}
+EXPORT_SYMBOL_GPL(aead_register_instance);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Authenticated Encryption with Associated Data (AEAD)");