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8227542: Manifest improved jar headers

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Reviewed-by: sspitsyn, mschoene
This commit is contained in:
Alex Menkov 2019-11-14 15:06:11 -08:00
parent 0e4b718a25
commit 3bbc499f06
2 changed files with 36 additions and 0 deletions
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7
src/java.instrument/share/classes/java/lang/instrument/package-info.java
View File

@ -32,6 +32,13 @@
* programs running on the JVM. The mechanism for instrumentation is modification
* of the byte-codes of methods.
*
* <p> Note: developers/admininstrators are responsible for verifying
* the trustworthiness of content and structure of the Java Agents they deploy,
* since those are able to arbitrarily transform the bytecode from other JAR files.
* Since that happens after the Jars containing the bytecode have been verified
* as trusted, the trustworthiness of a Java Agent can determine the trust towards
* the entire program.
*
* <p> An agent is deployed as a JAR file. An attribute in the JAR file manifest
* specifies the agent class which will be loaded to start the agent. Agents can
* be started in several ways:

29
src/java.instrument/share/native/libinstrument/InvocationAdapter.c
View File

@ -202,6 +202,17 @@ DEF_Agent_OnLoad(JavaVM *vm, char *tail, void * reserved) {
*/
oldLen = (int)strlen(premainClass);
newLen = modifiedUtf8LengthOfUtf8(premainClass, oldLen);
/*
* According to JVMS class name is represented as CONSTANT_Utf8_info,
* so its length is u2 (i.e. must be <= 0xFFFF).
*/
if (newLen > 0xFFFF) {
fprintf(stderr, "-javaagent: Premain-Class value is too big\n");
free(jarfile);
if (options != NULL) free(options);
freeAttributes(attributes);
return JNI_ERR;
}
if (newLen == oldLen) {
premainClass = strdup(premainClass);
} else {
@ -360,6 +371,17 @@ DEF_Agent_OnAttach(JavaVM* vm, char *args, void * reserved) {
*/
oldLen = (int)strlen(agentClass);
newLen = modifiedUtf8LengthOfUtf8(agentClass, oldLen);
/*
* According to JVMS class name is represented as CONSTANT_Utf8_info,
* so its length is u2 (i.e. must be <= 0xFFFF).
*/
if (newLen > 0xFFFF) {
fprintf(stderr, "Agent-Class value is too big\n");
free(jarfile);
if (options != NULL) free(options);
freeAttributes(attributes);
return AGENT_ERROR_BADJAR;
}
if (newLen == oldLen) {
agentClass = strdup(agentClass);
} else {
@ -485,6 +507,13 @@ jint loadAgent(JNIEnv* env, jstring path) {
// The value of Launcher-Agent-Class is in UTF-8, convert it to modified UTF-8
oldLen = (int) strlen(agentClass);
newLen = modifiedUtf8LengthOfUtf8(agentClass, oldLen);
/*
* According to JVMS class name is represented as CONSTANT_Utf8_info,
* so its length is u2 (i.e. must be <= 0xFFFF).
*/
if (newLen > 0xFFFF) {
goto releaseAndReturn;
}
if (newLen == oldLen) {
agentClass = strdup(agentClass);
} else {