[Bug 2642] [sshconnect2] publickey authentication only properly works if used first: pubkey_prepare doesn't work after pubkey_cleanup
https://bugzilla.mindrot.org/show_bug.cgi?id=2642 Damien Miller changed: What|Removed |Added Status|RESOLVED|CLOSED --- Comment #9 from Damien Miller --- Close all resolved bugs after release of OpenSSH 7.7. -- You are receiving this mail because: You are watching someone on the CC list of the bug. You are watching the assignee of the bug. ___ openssh-bugs mailing list openssh-bugs@mindrot.org https://lists.mindrot.org/mailman/listinfo/openssh-bugs
[Bug 2642] [sshconnect2] publickey authentication only properly works if used first: pubkey_prepare doesn't work after pubkey_cleanup
https://bugzilla.mindrot.org/show_bug.cgi?id=2642 Damien Miller changed: What|Removed |Added Resolution|--- |FIXED Status|NEW |RESOLVED --- Comment #8 from Damien Miller --- Patch applied - this will be in OpenSSH 7.4. Thanks! -- You are receiving this mail because: You are watching someone on the CC list of the bug. You are watching the assignee of the bug. ___ openssh-bugs mailing list openssh-bugs@mindrot.org https://lists.mindrot.org/mailman/listinfo/openssh-bugs
[Bug 2642] [sshconnect2] publickey authentication only properly works if used first: pubkey_prepare doesn't work after pubkey_cleanup
https://bugzilla.mindrot.org/show_bug.cgi?id=2642 Darren Tucker changed: What|Removed |Added Attachment #2900|ok?(dtuc...@zip.com.au) |ok+ Flags|| -- You are receiving this mail because: You are watching the assignee of the bug. You are watching someone on the CC list of the bug. ___ openssh-bugs mailing list openssh-bugs@mindrot.org https://lists.mindrot.org/mailman/listinfo/openssh-bugs
[Bug 2642] [sshconnect2] publickey authentication only properly works if used first: pubkey_prepare doesn't work after pubkey_cleanup
https://bugzilla.mindrot.org/show_bug.cgi?id=2642 Damien Miller changed: What|Removed |Added CC||dtuc...@zip.com.au Attachment #2900||ok?(dtuc...@zip.com.au) Flags|| --- Comment #7 from Damien Miller --- Comment on attachment 2900 --> https://bugzilla.mindrot.org/attachment.cgi?id=2900 Only reset 'tried' count (on reset) and 'isprivate' (when freeing key) I think this is correct. Can you take a look, Darren? -- You are receiving this mail because: You are watching someone on the CC list of the bug. You are watching the assignee of the bug. ___ openssh-bugs mailing list openssh-bugs@mindrot.org https://lists.mindrot.org/mailman/listinfo/openssh-bugs
[Bug 2642] [sshconnect2] publickey authentication only properly works if used first: pubkey_prepare doesn't work after pubkey_cleanup
https://bugzilla.mindrot.org/show_bug.cgi?id=2642 Vincent Brillault changed: What|Removed |Added Attachment #2895|0 |1 is obsolete|| --- Comment #6 from Vincent Brillault --- Created attachment 2900 --> https://bugzilla.mindrot.org/attachment.cgi?id=2900&action=edit Only reset 'tried' count (on reset) and 'isprivate' (when freeing key) Thanks for the review! > I not sure I properly understand why you change modifies id->tried. My goal was to emulate the existing behavior: - As the key list was rebuild between two authentications, the order was always the same, with 'tried' set to 0 (xcalloc) - When a key is tried, it is immediately moved to the end of the list and the 'tried' counter is increased My first loop continues to move keys to the end until the original order is found (all keys have been 'tried' (i.e moved) the same time) My second loop is resetting the 'tried' count because I understand it is used in userauth_pubkey in the while loop to make that the keys are not used twice (see https://github.com/openssh/openssh-portable/blob/master/sshconnect2.c#L1438). > Is it to move all tried keys to the end of the list? I think it > might be clearer to do something like the attached. It's a little > longer, but IMO easier to understand its intent. Mmm, I understand that by design, all keys are already at the end of the list. If resetting the order is not important, just clearing the id->tried should be enough >> Also, I don't understand why you reset isprivate. I think this might >> cause re-prompting for passwords to load keys that have already been >> loaded. > oh, I see. You reset isprivate because the key is subsequently freed Exactly! I was not sure where to reset the value, in the 'if' block, where the value is initialized (but it's not freed yet, so why?) or when it's freed (but it was not always initialized on that execution path). I've attached a stripped-down version of the patch, which only reset the 'tried' count and reset the 'isprivate' id after the key has been freed -- You are receiving this mail because: You are watching the assignee of the bug. You are watching someone on the CC list of the bug. ___ openssh-bugs mailing list openssh-bugs@mindrot.org https://lists.mindrot.org/mailman/listinfo/openssh-bugs
[Bug 2642] [sshconnect2] publickey authentication only properly works if used first: pubkey_prepare doesn't work after pubkey_cleanup
https://bugzilla.mindrot.org/show_bug.cgi?id=2642 --- Comment #5 from Damien Miller --- (In reply to Damien Miller from comment #4) > Created attachment 2898 [details] > fixed diff > > typo in previous oh, I see. You reset isprivate because the key is subsequently freed -- You are receiving this mail because: You are watching the assignee of the bug. You are watching someone on the CC list of the bug. ___ openssh-bugs mailing list openssh-bugs@mindrot.org https://lists.mindrot.org/mailman/listinfo/openssh-bugs
[Bug 2642] [sshconnect2] publickey authentication only properly works if used first: pubkey_prepare doesn't work after pubkey_cleanup
https://bugzilla.mindrot.org/show_bug.cgi?id=2642 Damien Miller changed: What|Removed |Added Attachment #2897|0 |1 is obsolete|| --- Comment #4 from Damien Miller --- Created attachment 2898 --> https://bugzilla.mindrot.org/attachment.cgi?id=2898&action=edit fixed diff typo in previous -- You are receiving this mail because: You are watching the assignee of the bug. You are watching someone on the CC list of the bug. ___ openssh-bugs mailing list openssh-bugs@mindrot.org https://lists.mindrot.org/mailman/listinfo/openssh-bugs
[Bug 2642] [sshconnect2] publickey authentication only properly works if used first: pubkey_prepare doesn't work after pubkey_cleanup
https://bugzilla.mindrot.org/show_bug.cgi?id=2642 Damien Miller changed: What|Removed |Added Blocks||2594 Referenced Bugs: https://bugzilla.mindrot.org/show_bug.cgi?id=2594 [Bug 2594] Tracking bug for OpenSSH 7.4 release -- You are receiving this mail because: You are watching someone on the CC list of the bug. You are watching the assignee of the bug. ___ openssh-bugs mailing list openssh-bugs@mindrot.org https://lists.mindrot.org/mailman/listinfo/openssh-bugs
[Bug 2642] [sshconnect2] publickey authentication only properly works if used first: pubkey_prepare doesn't work after pubkey_cleanup
https://bugzilla.mindrot.org/show_bug.cgi?id=2642 Damien Miller changed: What|Removed |Added CC||d...@mindrot.org Assignee|unassigned-b...@mindrot.org |d...@mindrot.org --- Comment #3 from Damien Miller --- Created attachment 2897 --> https://bugzilla.mindrot.org/attachment.cgi?id=2897&action=edit more clear pubkey_reset() Thanks for looking at this. I not sure I properly understand why you change modifies id->tried. Is it to move all tried keys to the end of the list? I think it might be clearer to do something like the attached. It's a little longer, but IMO easier to understand its intent. Also, I don't understand why you reset isprivate. I think this might cause re-prompting for passwords to load keys that have already been loaded. -- You are receiving this mail because: You are watching the assignee of the bug. You are watching someone on the CC list of the bug. ___ openssh-bugs mailing list openssh-bugs@mindrot.org https://lists.mindrot.org/mailman/listinfo/openssh-bugs
[Bug 2642] [sshconnect2] publickey authentication only properly works if used first: pubkey_prepare doesn't work after pubkey_cleanup
https://bugzilla.mindrot.org/show_bug.cgi?id=2642 Vincent Brillault changed: What|Removed |Added CC||g...@lerya.net --- Comment #2 from Vincent Brillault --- Created attachment 2895 --> https://bugzilla.mindrot.org/attachment.cgi?id=2895&action=edit Only reorder and resent count of authctxt->keys between authentications (Sorry for the double-posting, I am not sure what is the preferred way of submitting patches) While taking another look at the code, I realised that most of the accesses to the authctxt->keys list or its content do not modify it (the attached patch 'constifies' the arguments functions called on the content of the list, to make it easier to see that they don't modify them). There is only one place (not counting prepare/cleanup) that modifies it, userauth_pubkey. That function: - Re-order the key, increasing the tries count each time (up to 2 if it loops) - Set the isprivate flag on private keys when they are loaded This patch (also available at https://github.com/openssh/openssh-portable/pull/57): - Unset the isprivate flag on private keys when they are freed/cleared - Add a pubkey_reset function (called between authentication) that re-re-order the keys and reset the 'tries' count This patch/the code could be simplified: - The 'constification' could be ignored - If we don't care about the order in which keys are tested, the re-ordering could be removed - pubkey_reset could be inlined (esp. if the reordering is removed) - pubkey_cleanup could be inlined (only called once) -- You are receiving this mail because: You are watching the assignee of the bug. ___ openssh-bugs mailing list openssh-bugs@mindrot.org https://lists.mindrot.org/mailman/listinfo/openssh-bugs
[Bug 2642] [sshconnect2] publickey authentication only properly works if used first: pubkey_prepare doesn't work after pubkey_cleanup
https://bugzilla.mindrot.org/show_bug.cgi?id=2642
--- Comment #1 from Vincent Brillault ---
I believe I've been able to observe the bug on the certificate path.
Step to reproduce:
- Configure sshd with AuthenticationMethods
keyboard-interactive:pam,publickey (in fact, can be any combination of
2 methods)
- Generate a valid certificate file
- Run ssh -o 'CertificateFile=${certfile}' -o IdentitiesOnly=yes -vvv
${host}, properly authenticate the first time. Logs should contain:
* `debug2: key: ${certfile} (${pointer}), explicit` before the first
authentication
* No corresponding line after the first authentication (the
certificate disappeared)
On my setup, `key_is_cert(key)` seems to return 0 when accessing the
freed memory, leading not to a crash but simply to that key being
ignored.
If run under valgrind, logs should contain (using
1a6f9d2e2493d445cd9ee496e6e3c2a2f283f66a of
https://github.com/openssh/openssh-portable):
Authenticated with partial success.
==25112== Invalid read of size 4
==25112==at 0x1300E9: sshkey_is_cert (sshkey.c:308)
==25112==by 0x1253A6: pubkey_prepare (sshconnect2.c:1298)
==25112==by 0x1289F6: input_userauth_failure (sshconnect2.c:564)
==25112==by 0x154758: ssh_dispatch_run (dispatch.c:119)
==25112==by 0x12852B: ssh_userauth2 (sshconnect2.c:402)
==25112==by 0x124D56: ssh_login (sshconnect.c:1383)
==25112==by 0x113898: main (ssh.c:1418)
==25112== Address 0x6138060 is 0 bytes inside a block of size 64
free'd
==25112==at 0x4C2C4AB: free (vg_replace_malloc.c:473)
==25112==by 0x12597A: pubkey_cleanup (sshconnect2.c:1411)
==25112==by 0x1289EE: input_userauth_failure (sshconnect2.c:563)
==25112==by 0x154758: ssh_dispatch_run (dispatch.c:119)
==25112==by 0x12852B: ssh_userauth2 (sshconnect2.c:402)
==25112==by 0x124D56: ssh_login (sshconnect.c:1383)
==25112==by 0x113898: main (ssh.c:1418)
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