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8264864: Multiple byte tag not supported by ASN.1 encoding #3391

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@wangweij wangweij commented Apr 8, 2021

This code change does not intend to support multiple byte tags. Instead, it aims to fail more gracefully when such a tag is encountered. For DerValue constructors from an encoding (type I), an IOException will be thrown since it's already in the throws clause. For constructors from tag and value (type II), an IllegalArgumentException will be thrown. All existing type II callers inside JDK use tag numbers smaller than 31.


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  • JDK-8264864: Multiple byte tag not supported by ASN.1 encoding

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8264864: Multiple byte tag not supported by ASN.1 encoding
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@bridgekeeper bridgekeeper bot commented Apr 8, 2021

👋 Welcome back weijun! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

@openjdk openjdk bot added the rfr label Apr 8, 2021
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@wangweij The following label will be automatically applied to this pull request:

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@XueleiFan XueleiFan left a comment

Looks good to me, except a minor comment.

@@ -221,6 +221,9 @@ public boolean isConstructed(byte constructedTag) {
* Creates a new DerValue by specifying all its fields.
*/
DerValue(byte tag, byte[] buffer, int start, int end, boolean allowBER) {
if ((tag & 0x1f) == 0x1f) {
throw new IllegalArgumentException("Tag number 31 is not supported");

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@XueleiFan

XueleiFan Apr 8, 2021
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As number 31 just means the tag is bigger than 31, Is it more accuracy by using "Tag number over 30 is not supported"?

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@wangweij

wangweij Apr 8, 2021
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Well, it's a little delicate here. Even if we support multi-byte tag one day, this constructor will still only be used to create a single-byte tag DerValue, and it's illegal for a single byte tag to end with 0x1f. So the words above is to remind people that they cannot create a tag number 31 DerValue just because it seems it still fits into the 5 bits. Precisely, the words should be "this constructor only supports tag number between 0 and 30", but... I'll choose your words.

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XueleiFan Apr 8, 2021
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It makes sense. Your words is good to me.

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@openjdk openjdk bot commented Apr 8, 2021

@wangweij This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8264864: Multiple byte tag not supported by ASN.1 encoding

Reviewed-by: xuelei

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 58 new commits pushed to the master branch:

  • 5bd6c74: 8236127: Use value of --icon CLI option to set icon for exe installers
  • 81d35e4: 8264063: Outer Safepoint poll load should not reference the head of inner strip mined loop.
  • 04fa1ed: 8264848: [macos] libjvm.dylib linker warning due to macOS version mismatch
  • 214d6e2: 8263506: Make sun.net.httpserver.UnmodifiableHeaders unmodifiable
  • af13c64: 8264711: More runtime TRAPS cleanups
  • 3aec2d9: 8264718: Shenandoah: enable string deduplication during root scanning
  • 255afbe: 8264672: runtime/ParallelLoad/ParallelSuperTest.java timed out
  • ec599da: 8264633: Add missing logging to PlatformRecording#stop
  • e89542f: 8264352: AArch64: Optimize vector "not/andNot" for NEON and SVE
  • 016db40: 8263907: Specification of CellRendererPane::paintComponent(..Rectangle) should clearly mention which method it delegates the call to
  • ... and 48 more: https://git.openjdk.java.net/jdk/compare/9c283da1752db3b8c89cc21016277e43eadd6cf4...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

@openjdk openjdk bot added the ready label Apr 8, 2021
@@ -315,6 +318,9 @@ public DerValue(byte[] encoding) throws IOException {
}
int pos = offset;
tag = buf[pos++];
if ((tag & 0x1f) == 0x1f) {
throw new IOException("Tag number over 30 is not supported");

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@jnimeh

jnimeh Apr 8, 2021
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Would it be useful for these types of exception messages to either display the offending tag value or perhaps the tag offset? Just thinking it might be a nice thing for the recipient to know where in the DER encoding the issue is.

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wangweij Apr 8, 2021
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I don't want to go on reading the following bytes to find out what the intended tag number is, because that somehow shows I do understand the encoding a lot but still don't want to support it (well, actually I only understand a little). There are only 2 kinds of tags: one <= 30 and one >= 31. IMHO, the message has already expressed the meaning that we only support the 1st one.

An alternative message I can think of is "Unsupported tag byte: 0xBF", but it looks too cryptic.

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jnimeh Apr 8, 2021
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I think that is fair. If you don't want to read ahead like that, what about using the "offset" or "pos" field to give a message like "Tag number over 30 at offset NN is not supported" (something like that, at least) Maybe don't worry about the tag value itself, but at least the position in the data stream. Just a suggestion only, no strong feelings about this either way.

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wangweij Apr 8, 2021
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There is an offset value here but I have really no idea if the user knows where to count from. If we say "offset" then we probably need to tell what data block we are talking about. What if the DerValue is just a portion of a bigger data block?

That said, if you really like it, I can add an offset like "tag byte at offset nnnn". I just hope the user can find it.

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@wangweij wangweij commented Apr 8, 2021

/integrate

@wangweij wangweij closed this Apr 8, 2021
@wangweij wangweij deleted the wangweij:8264864 branch Apr 8, 2021
@wangweij wangweij restored the wangweij:8264864 branch Apr 8, 2021
@wangweij wangweij reopened this Apr 8, 2021
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@wangweij wangweij commented Apr 8, 2021

/integrate

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@wangweij wangweij commented Apr 8, 2021

/integrate

@openjdk openjdk bot closed this Apr 8, 2021
@openjdk openjdk bot added integrated and removed ready labels Apr 8, 2021
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@openjdk openjdk bot commented Apr 8, 2021

@wangweij Since your change was applied there have been 61 commits pushed to the master branch:

  • ccefa5e: 8261625: Add Elements.isAutomaticModule(ModuleElement)
  • 8a23580: 8264428: Cleanup usages of StringBuffer in java.desktop
  • 308f679: 8264454: Jaxp unit test from open jdk needs to be improved
  • 5bd6c74: 8236127: Use value of --icon CLI option to set icon for exe installers
  • 81d35e4: 8264063: Outer Safepoint poll load should not reference the head of inner strip mined loop.
  • 04fa1ed: 8264848: [macos] libjvm.dylib linker warning due to macOS version mismatch
  • 214d6e2: 8263506: Make sun.net.httpserver.UnmodifiableHeaders unmodifiable
  • af13c64: 8264711: More runtime TRAPS cleanups
  • 3aec2d9: 8264718: Shenandoah: enable string deduplication during root scanning
  • 255afbe: 8264672: runtime/ParallelLoad/ParallelSuperTest.java timed out
  • ... and 51 more: https://git.openjdk.java.net/jdk/compare/9c283da1752db3b8c89cc21016277e43eadd6cf4...master

Your commit was automatically rebased without conflicts.

Pushed as commit 3d2b4cc.

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@openjdk openjdk bot removed the rfr label Apr 8, 2021
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@wangweij The command integrate can only be used in open pull requests.

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@wangweij The command integrate can only be used in open pull requests.

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