write in 30M

hc

2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc

 kernel/kernel/kexec.c
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@@ -1,9 +1,7 @@
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+// SPDX-License-Identifier: GPL-2.0-only
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 /*
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  * kexec.c - kexec_load system call
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  * Copyright (C) 2002-2004 Eric Biederman  <ebiederm@xmission.com>
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- *
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- * This source code is licensed under the GNU General Public License,
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- * Version 2.  See the file COPYING for more details.
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  */
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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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@@ -112,6 +110,14 @@
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 	unsigned long i;
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 	int ret;
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+	/*
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+	 * Because we write directly to the reserved memory region when loading
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+	 * crash kernels we need a serialization here to prevent multiple crash
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+	 * kernels from attempting to load simultaneously.
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+	 */
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+	if (!kexec_trylock())
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+		return -EBUSY;
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+
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 	if (flags & KEXEC_ON_CRASH) {
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 		dest_image = &kexec_crash_image;
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 		if (kexec_crash_image)
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@@ -123,7 +129,8 @@
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 	if (nr_segments == 0) {
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 		/* Uninstall image */
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 		kimage_free(xchg(dest_image, NULL));
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-		return 0;
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+		ret = 0;
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+		goto out_unlock;
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 	}
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 	if (flags & KEXEC_ON_CRASH) {
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 		/*
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@@ -136,7 +143,7 @@
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 	ret = kimage_alloc_init(&image, entry, nr_segments, segments, flags);
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 	if (ret)
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-		return ret;
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+		goto out_unlock;
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 	if (flags & KEXEC_PRESERVE_CONTEXT)
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 		image->preserve_context = 1;
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@@ -161,6 +168,10 @@
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 	kimage_terminate(image);
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+	ret = machine_kexec_post_load(image);
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+	if (ret)
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+		goto out;
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+
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 	/* Install the new kernel and uninstall the old */
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 	image = xchg(dest_image, image);
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@@ -169,6 +180,8 @@
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 		arch_kexec_protect_crashkres();
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 	kimage_free(image);
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+out_unlock:
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+	kexec_unlock();
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 	return ret;
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 }
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@@ -203,8 +216,16 @@
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 		return -EPERM;
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 	/* Permit LSMs and IMA to fail the kexec */
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-	result = security_kernel_load_data(LOADING_KEXEC_IMAGE);
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+	result = security_kernel_load_data(LOADING_KEXEC_IMAGE, false);
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 	if (result < 0)
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+		return result;
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+
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+	/*
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+	 * kexec can be used to circumvent module loading restrictions, so
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+	 * prevent loading in that case
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+	 */
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+	result = security_locked_down(LOCKDOWN_KEXEC);
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+	if (result)
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 		return result;
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 	/*
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@@ -237,20 +258,7 @@
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 		((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))
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 		return -EINVAL;
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-	/* Because we write directly to the reserved memory
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-	 * region when loading crash kernels we need a mutex here to
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-	 * prevent multiple crash  kernels from attempting to load
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-	 * simultaneously, and to prevent a crash kernel from loading
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-	 * over the top of a in use crash kernel.
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-	 *
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-	 * KISS: always take the mutex.
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-	 */
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-	if (!mutex_trylock(&kexec_mutex))
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-		return -EBUSY;
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-
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 	result = do_kexec_load(entry, nr_segments, segments, flags);
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-
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-	mutex_unlock(&kexec_mutex);
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 	return result;
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 }
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@@ -291,20 +299,7 @@
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 			return -EFAULT;
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 	}
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-	/* Because we write directly to the reserved memory
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-	 * region when loading crash kernels we need a mutex here to
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-	 * prevent multiple crash  kernels from attempting to load
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-	 * simultaneously, and to prevent a crash kernel from loading
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-	 * over the top of a in use crash kernel.
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-	 *
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-	 * KISS: always take the mutex.
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-	 */
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-	if (!mutex_trylock(&kexec_mutex))
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-		return -EBUSY;
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-
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 	result = do_kexec_load(entry, nr_segments, ksegments, flags);
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-
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-	mutex_unlock(&kexec_mutex);
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 	return result;
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 }