Keep RNG seed file descriptor open until the RNG is freed. #7586

kareem-wolfssl · 2024-05-24T19:43:20Z

Description

Keep RNG seed file descriptor open until the RNG is freed.
Fixes #7197

Testing

Built in tests

Checklist

added tests
updated/added doxygen
updated appropriate READMEs
Updated manual and documentation

wolfcrypt/src/random.c

kareem-wolfssl · 2024-08-22T17:38:56Z

Retest this please

…pen. This fixes the case where wc_FreeRng is called when _InitRng was not called on the RNG. Since the FD value defaults to 0 before _InitRng was called, and 0 is potentially a valid FD, it was being closed.

Gate keeping the seed FD open behind WOLFSSL_KEEP_RNG_SEED_FD_OPEN and only enable by default for HAProxy. It is causing issues on OS X and may cause issues on other OSes, and is generally a major behavior change.

Improve logic for opening RNG seed FD.

dgarske · 2025-12-23T16:59:00Z

wolfcrypt/src/random.c

-        os->fd = open("/dev/urandom", O_RDONLY);
-        #if defined(DEBUG_WOLFSSL)
-            WOLFSSL_MSG("opened /dev/urandom.");
+        #ifdef WOLFSSL_KEEP_RNG_SEED_FD_OPEN


This section might be easier to read with two separate versions of the code... one for existing and another for keeping seed file descriptor open.

…rateSeed.

douzzer · 2025-12-24T23:05:39Z

retest this please

Found unhandled hudson.remoting.RequestAbortedException exception:
java.io.StreamCorruptedException: invalid stream header: 636F7272
	hudson.remoting.Request.abort(Request.java:358)
	hudson.remoting.Channel.terminate(Channel.java:1189)
	hudson.remoting.SynchronousCommandTransport$ReaderThread.run(SynchronousCommandTransport.java:95)

douzzer

Looks mostly ready. I left one substantive change req, some optional nits, and some suggestions.

douzzer · 2025-12-24T23:13:25Z

wolfssl/wolfcrypt/random.h

+        byte seedFdOpen:1;
+        byte keepSeedFdOpen:1;


these need to be parent type WC_BITFIELD, not byte.

douzzer · 2025-12-24T23:16:12Z

wolfcrypt/src/random.c

+                WOLFSSL_MSG("opened /dev/urandom.");
+            #endif
+            if (os->fd == -1)
+        #endif


the #else and #endif associations are getting pretty gnarly here -- I suggest adding /* !NO_DEV_URANDOM */ after this one, and similarly annotating the others with comments.

douzzer · 2025-12-24T23:16:45Z

wolfcrypt/src/random.c

+                os->seedFdOpen = 1;
+            }
+        }
+    #else


this is the sort of #else that's begging for annotation with a comment.

douzzer · 2025-12-24T23:19:43Z

wolfcrypt/src/random.c


+#if defined(WOLFSSL_KEEP_RNG_SEED_FD_OPEN) && !defined(USE_WINDOWS_API)
+    if (!rng->seed.seedFdOpen)
+        rng->seed.fd = -1;


It would be nice if we had an XBADFD macro to go with our XBADFILE macro, but alas we do not. If you're feeling inspired, add XBADFD in wc_port.h and use it here, bearing in mind that it will need to be defined for every target that needs to support WOLFSSL_KEEP_RNG_SEED_FD_OPEN.

I've only added it for the default target and Zephyr for now, I'm not expecting this macro to be used on embedded systems but XBADFD can easily be expanded if needed.

douzzer · 2025-12-24T23:20:53Z

wolfcrypt/src/random.c

+        rng->seed.fd = -1;
+        rng->seed.seedFdOpen = 0;


Why do you need to separately track .seedFdOpen? Can't you just use .fd != -1 as a decisive proxy for the fd being open?

Unfortunately I can't. fd is initialized to 0 before InitRng is called, so I can't assume that it will be set to -1 as there are some cases where InitRng is not being called before the RNG is used or closed (which is not supposed to happen but it should still be handled gracefully). And 0 is a valid fd which could be returned by open, so I can't use that as a condition either.

kareem-wolfssl self-assigned this May 24, 2024

TimWolla reviewed May 27, 2024

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wolfcrypt/src/random.c Outdated Show resolved Hide resolved

kareem-wolfssl force-pushed the gh7197 branch from 3bfe17f to 54b3613 Compare May 28, 2024 23:16

kareem-wolfssl force-pushed the gh7197 branch from 54b3613 to 1328b26 Compare November 15, 2024 18:11

kareem-wolfssl added 5 commits December 18, 2025 11:15

Keep RNG seed file descriptor open until the RNG is freed.

ea43bcb

Initalize RNG seed fd in _InitRng.

6bcbfec

Reset fd after closing it.

fb880e9

Only attempt to close RNG file descriptor on platforms with XCLOSE.

2e83b97

Only use -1 for uninitialized fds as 0 is a valid fd.

0420c94

kareem-wolfssl force-pushed the gh7197 branch from 87e70a7 to 0420c94 Compare December 18, 2025 18:22

kareem-wolfssl added 3 commits December 18, 2025 15:27

Track if RNG seed FD was opened and only close it if it was already o…

755097d

…pen. This fixes the case where wc_FreeRng is called when _InitRng was not called on the RNG. Since the FD value defaults to 0 before _InitRng was called, and 0 is potentially a valid FD, it was being closed.

Rename fdOpen to seedFdOpen to avoid potential conflicts.

b0b840a

Gate keeping the seed FD open behind WOLFSSL_KEEP_RNG_SEED_FD_OPEN and only enable by default for HAProxy. It is causing issues on OS X and may cause issues on other OSes, and is generally a major behavior change.

Only keep /dev/urandom open, close /dev/random after each use.

3e59b83

Improve logic for opening RNG seed FD.

kareem-wolfssl mentioned this pull request Dec 22, 2025

[Bug]: [haproxy] blocking when using chroot + wolfssl #7197

Open

kareem-wolfssl assigned wolfSSL-Bot and unassigned kareem-wolfssl Dec 22, 2025

dgarske requested changes Dec 23, 2025

View reviewed changes

dgarske assigned kareem-wolfssl Dec 23, 2025

dgarske requested a review from douzzer December 23, 2025 16:59

kareem-wolfssl added 2 commits December 23, 2025 14:43

Merge remote-tracking branch 'upstream/master' into gh7197

cb81cc8

Separate new /dev/urandom opening logic into a new section in wc_Gene…

06d8f69

…rateSeed.

douzzer requested changes Dec 24, 2025

View reviewed changes

kareem-wolfssl added 2 commits December 24, 2025 17:05

Merge remote-tracking branch 'upstream/master' into gh7197

496d124

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Keep RNG seed file descriptor open until the RNG is freed. #7586

Keep RNG seed file descriptor open until the RNG is freed. #7586

kareem-wolfssl commented May 24, 2024 •

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Keep RNG seed file descriptor open until the RNG is freed. #7586

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kareem-wolfssl commented Aug 22, 2024

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douzzer commented Dec 24, 2025

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kareem-wolfssl commented May 24, 2024 •

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