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2024-10-22 8ac6c7a54ed1b98d142dce24b11c6de6a1e239a5 
 kernel/kernel/kexec.c
....@@ -1,9 +1,7 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  * kexec.c - kexec_load system call
34  * Copyright (C) 2002-2004 Eric Biederman  <ebiederm@xmission.com>
4
- *
5
- * This source code is licensed under the GNU General Public License,
6
- * Version 2.  See the file COPYING for more details.
75  */
86 
97 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
....@@ -112,6 +110,14 @@
112110 	unsigned long i;
113111 	int ret;
114112 
113
+	/*
114
+	 * Because we write directly to the reserved memory region when loading
115
+	 * crash kernels we need a serialization here to prevent multiple crash
116
+	 * kernels from attempting to load simultaneously.
117
+	 */
118
+	if (!kexec_trylock())
119
+		return -EBUSY;
120
+
115121 	if (flags & KEXEC_ON_CRASH) {
116122 		dest_image = &kexec_crash_image;
117123 		if (kexec_crash_image)
....@@ -123,7 +129,8 @@
123129 	if (nr_segments == 0) {
124130 		/* Uninstall image */
125131 		kimage_free(xchg(dest_image, NULL));
126
-		return 0;
132
+		ret = 0;
133
+		goto out_unlock;
127134 	}
128135 	if (flags & KEXEC_ON_CRASH) {
129136 		/*
....@@ -136,7 +143,7 @@
136143 
137144 	ret = kimage_alloc_init(&image, entry, nr_segments, segments, flags);
138145 	if (ret)
139
-		return ret;
146
+		goto out_unlock;
140147 
141148 	if (flags & KEXEC_PRESERVE_CONTEXT)
142149 		image->preserve_context = 1;
....@@ -161,6 +168,10 @@
161168 
162169 	kimage_terminate(image);
163170 
171
+	ret = machine_kexec_post_load(image);
172
+	if (ret)
173
+		goto out;
174
+
164175 	/* Install the new kernel and uninstall the old */
165176 	image = xchg(dest_image, image);
166177 
....@@ -169,6 +180,8 @@
169180 		arch_kexec_protect_crashkres();
170181 
171182 	kimage_free(image);
183
+out_unlock:
184
+	kexec_unlock();
172185 	return ret;
173186 }
174187 
....@@ -203,8 +216,16 @@
203216 		return -EPERM;
204217 
205218 	/* Permit LSMs and IMA to fail the kexec */
206
-	result = security_kernel_load_data(LOADING_KEXEC_IMAGE);
219
+	result = security_kernel_load_data(LOADING_KEXEC_IMAGE, false);
207220 	if (result < 0)
221
+		return result;
222
+
223
+	/*
224
+	 * kexec can be used to circumvent module loading restrictions, so
225
+	 * prevent loading in that case
226
+	 */
227
+	result = security_locked_down(LOCKDOWN_KEXEC);
228
+	if (result)
208229 		return result;
209230 
210231 	/*
....@@ -237,20 +258,7 @@
237258 		((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))
238259 		return -EINVAL;
239260 
240
-	/* Because we write directly to the reserved memory
241
-	 * region when loading crash kernels we need a mutex here to
242
-	 * prevent multiple crash  kernels from attempting to load
243
-	 * simultaneously, and to prevent a crash kernel from loading
244
-	 * over the top of a in use crash kernel.
245
-	 *
246
-	 * KISS: always take the mutex.
247
-	 */
248
-	if (!mutex_trylock(&kexec_mutex))
249
-		return -EBUSY;
250
-
251261 	result = do_kexec_load(entry, nr_segments, segments, flags);
252
-
253
-	mutex_unlock(&kexec_mutex);
254262 
255263 	return result;
256264 }
....@@ -291,20 +299,7 @@
291299 			return -EFAULT;
292300 	}
293301 
294
-	/* Because we write directly to the reserved memory
295
-	 * region when loading crash kernels we need a mutex here to
296
-	 * prevent multiple crash  kernels from attempting to load
297
-	 * simultaneously, and to prevent a crash kernel from loading
298
-	 * over the top of a in use crash kernel.
299
-	 *
300
-	 * KISS: always take the mutex.
301
-	 */
302
-	if (!mutex_trylock(&kexec_mutex))
303
-		return -EBUSY;
304
-
305302 	result = do_kexec_load(entry, nr_segments, ksegments, flags);
306
-
307
-	mutex_unlock(&kexec_mutex);
308303 
309304 	return result;
310305 }