57 lines
2.0 KiB
Plaintext
57 lines
2.0 KiB
Plaintext
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From: David Howells <dhowells@redhat.com>
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Date: Fri, 10 Sep 2010 08:59:51 +0000 (+0100)
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Subject: KEYS: Fix bug in keyctl_session_to_parent() if parent has no session
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keyring
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Git-commit: 3d96406c7da1ed5811ea52a3b0905f4f0e295376
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Patch-mainline: 2.6.36-rc4
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References: CVE-2010-2960 bnc#634637
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Introduced-by: 2.6.32
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KEYS: Fix bug in keyctl_session_to_parent() if parent has no session keyring
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Fix a bug in keyctl_session_to_parent() whereby it tries to check the ownership
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of the parent process's session keyring whether or not the parent has a session
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keyring [CVE-2010-2960].
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This results in the following oops:
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BUG: unable to handle kernel NULL pointer dereference at 00000000000000a0
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IP: [<ffffffff811ae4dd>] keyctl_session_to_parent+0x251/0x443
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...
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Call Trace:
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[<ffffffff811ae2f3>] ? keyctl_session_to_parent+0x67/0x443
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[<ffffffff8109d286>] ? __do_fault+0x24b/0x3d0
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[<ffffffff811af98c>] sys_keyctl+0xb4/0xb8
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[<ffffffff81001eab>] system_call_fastpath+0x16/0x1b
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if the parent process has no session keyring.
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If the system is using pam_keyinit then it mostly protected against this as all
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processes derived from a login will have inherited the session keyring created
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by pam_keyinit during the log in procedure.
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To test this, pam_keyinit calls need to be commented out in /etc/pam.d/.
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Reported-by: Tavis Ormandy <taviso@cmpxchg8b.com>
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Signed-off-by: David Howells <dhowells@redhat.com>
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Acked-by: Tavis Ormandy <taviso@cmpxchg8b.com>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Acked-by: Jeff Mahoney <jeffm@suse.com>
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---
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security/keys/keyctl.c | 3 ++-
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1 file changed, 2 insertions(+), 1 deletion(-)
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--- a/security/keys/keyctl.c
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+++ b/security/keys/keyctl.c
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@@ -1292,7 +1292,8 @@ long keyctl_session_to_parent(void)
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goto not_permitted;
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/* the keyrings must have the same UID */
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- if (pcred ->tgcred->session_keyring->uid != mycred->euid ||
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+ if ((pcred->tgcred->session_keyring &&
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+ pcred->tgcred->session_keyring->uid != mycred->euid) ||
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mycred->tgcred->session_keyring->uid != mycred->euid)
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goto not_permitted;
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