June 2010 - Darwin-kernel - lists.apple.com

Re: Process exit notifcation in a kext
by Justin C. Walker 23 Jun '10

23 Jun '10

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Re: kext version handling
by Michael Smith 23 Jun '10

23 Jun '10

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kext version handling
by Luciano 23 Jun '10

23 Jun '10

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com User-agent: KMail/1.9.5 Hi all! I have a question concerning kext version handling: If I want to ensure compatibility of a kext (i.e a driver) and a userspace library that accesses the functionality of the kext, what is the best way to do it? I know that there is the bundle version of a kext, but i dont see how a library could easily extract this information to make sure that the installed kext version is one with which it is compatible. I thought about using sysctl to expose the kext version info, but is this the right way to do it? Thx in advance for you help and best regards, Luciano _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: Process exit notifcation in a kext
by Bogdan Harjoc 23 Jun '10

23 Jun '10

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:cc:content-type :content-transfer-encoding; bh=BZhKnNwzznPeyUC9WSBpIOwWMJn771LauJCZS6WTRO0=; b=JXSpeDVh+ar3pKFJRY7Jfc8135itQKaWgYF4C+8pbX5XbeG9vs7SeC9uoJC5oNl0rg c0nthamukc185n9+I7SPJCQsmBnmqV3Tb7Hv8cam7xo3pVGcgw2Gnq5Ne9dHwh+S6FTP KSrcpN3TdIDLY+HL+CG5UaFWeX4VKryKDuvzc= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:cc :content-type:content-transfer-encoding; b=cBebc2OLahMViUiNA9xFa66ilYjmwTTCA5FSLgAV+bryn/e9WS6FhhstRQUeNH+ghu 1iK7uX+mFYajXVGCqGsaZB0dnEyJfjlUUHBm1C4gDydqh0De8b4jhM28XleJdMlb9//C veVbP55ZX+EnmCCknLBQ03bzlKqjLoUkfrLHw= On Tue, Jun 22, 2010 at 10:44 PM, Terry Lambert <tlambert(a)apple.com> wrote: > The tcp_input() doesn't happen in the context of a process, it happens in > the context of a kernel thread (the moral equivalent of netisr() on BSD > systems). The data gets unloaded onto a socket at the top end, but the > binding between a socket and a process is via a file descriptor, and any > given file descriptor could be referenced by multiple processes [...] Agreed here, there's no trivial way of mapping socket_t to pid. Since I'm only dealing with TCP sockets, I can get the pid in the 'attach' filter callback. The two possible cases are "connect()ed socket" which the process creates, and "accept()ed socket" for which I assume the pid is the same as its listening socket, which the process also creates. Thanks for the big picture, Bogdan _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: Process exit notifcation in a kext
by Terry Lambert 22 Jun '10

22 Jun '10

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com I'd like to ask is this approach is correct: call proc_find(pid) which takes a reference to the proc_t, and then proc_rele(pid) when the exit notification from kqueue comes. This avoids the race, but will the process exit while I am holding a reference to it ? True, because I would call pfind() in a callback coming from tcp_input() (and not from a user process). I was hoping for a way to tag a process (like one can tag mbuf's), is this somehow possible ? -- Terry _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… On Jun 18, 2010, at 3:00 AM, Bogdan Harjoc wrote: On Thu, Jun 17, 2010 at 9:24 PM, Terry Lambert <tlambert(a)apple.com> wrote: In addition, you have no guarantee that the locking order will happen the way you want it to, i.e. there is a race in acquiring the lock on the process list between you doing the pfind() and the process ID being reused between the time you decide a given PID is interesting to you and the time that the process reference is obtained on a process with that PID, such that it may not be the process you found interesting by the time you have the reference. It's undefined, which is why it's bad to use PID as a unique identifier for security purposes. The tcp_input() doesn't happen in the context of a process, it happens in the context of a kernel thread (the moral equivalent of netisr() on BSD systems). The data gets unloaded onto a socket at the top end, but the binding between a socket and a process is via a file descriptor, and any given file descriptor could be referenced by multiple processes, either via parent/child descriptor inheritance or explicit descriptor passing via UNIX domain socket. You could brute- force the lookup to try and figure your way back to the process(es) that have the descriptor open, which would be prohibitively expensive, but it's racy for the same reasons as before, and whoever reads from the thing first is the "real" process of the moment. And that's indeterminate. Are you going to be building your own kernel? If you're building your own kernel, you could potentially add a tag field to the proc structure and provide your own SPI for an accessor/mutator for the tag field. That would be reasonable if this were a research project rather than being intended as a commercial product. You still have to figure out a way to get back to the process from the socket, though, if you want to do the lookup in tcp_input(), so you're still stuck there. You could add a linked list of processes to the socket, and modify the accept/connect/bind/shutdown/close code to maintain the list under the proper locking conditions, but unless it's the difference between you getting your PhD and not getting it, it's probably more trouble than it's worth. This email sent to site_archiver(a)lists.apple.com

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Re: problem calling Mach RPC function
by Bill Appleton 18 Jun '10

18 Jun '10

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Re: Process exit notifcation in a kext
by Michael Smith 18 Jun '10

18 Jun '10

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Re: problem calling Mach RPC function
by Bill Appleton 18 Jun '10

18 Jun '10

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problem calling Mach RPC function
by Bill Appleton 18 Jun '10

18 Jun '10

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Re: Process exit notifcation in a kext
by Bogdan Harjoc 18 Jun '10

18 Jun '10

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type :content-transfer-encoding; bh=/J+dNhDVj7gpn2AegN3QO8Y0u1oWXmPQQ1jI4Tkn5Aw=; b=jNszU5WxvljS4NUfBx/zzD12skka7/4ZVns64FAdqoJVAQBZFb5e2V4N4uolTgW23x 2S2eZg8QG4fW8hnqeGKyLjwumhrCmzdB/WYOw5dGMV5HkP7BUTAmzSmRJUz3kEUd9zvV WAif2bArglS70qHU/WB5anrwPrHEBo58Movmc= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; b=M9GaCELMkFEMa7Ga91k44AtPnYmTTo22luo4OiRcpcihlocjxtlwJWVc8Pkl1pUEzV ssS5Q030P8dh+wvuxTyvSC/+A2dbxXE0+1VwBmq9rbWtJqPGp696o7Q/jOPL5d2ZSzbL u67lW8jov7rnhli13bbVazvqFv0Pv2R6mQ+vM= On Thu, Jun 17, 2010 at 9:24 PM, Terry Lambert <tlambert(a)apple.com> wrote: >> I'd like to ask is this approach is correct: call >> proc_find(pid) which takes a reference to the proc_t, and then >> proc_rele(pid) when the exit notification from kqueue comes. This >> avoids the race, but will the process exit while I am holding a >> reference to it ? > In addition, you have no guarantee that the locking order will happen the > way you want it to, i.e. there is a race in acquiring the lock on the > process list between you doing the pfind() and the process ID being reused > between the time you decide a given PID is interesting to you and the time > that the process reference is obtained on a process with that PID, such that > it may not be the process you found interesting by the time you have the > reference. It's undefined, which is why it's bad to use PID as a unique > identifier for security purposes. True, because I would call pfind() in a callback coming from tcp_input() (and not from a user process). I was hoping for a way to tag a process (like one can tag mbuf's), is this somehow possible ? > -- Terry Thanks again, Bogdan _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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