FW: FW: mq_open
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From: Berger, Lutz (External) on 6 Aug 2010 02:00 Hello gentleman, we have a problem with mq_open, shm_open and sem_open As stated in the manpage of "open(2)", the permissions of the created file are (mode & ~umask). But what is the use of the mode parameter, it it is not used like the programmers intention? On HP Unix or TRU64 the mode parameter is not modified. Could you please check, if this is a bug or a faulty system design on linux? Thanks in advance. Mit freundlichen Gr��en / With best regards Lutz Berger EADS Deutschland GmbH Military Air Systems Integrated Team ASTA - MSF1 85077 Manching Telephone: +49 (0) 8459.81-79443 Fax: +49 (0) 8459.81-66992 Mobile: +49 (0) 172.8223258 e-Mail: lutz.berger.external(a)eads.com www.eads.com EADS Deutschland GmbH Registered Office: Ottobrunn District Court of Munich HRB 107 648 Chairman of the Supervisory Board: Dr. Thomas Enders Managing Directors: Dr. Stefan Zoller (chairman), Dr. Christoph Hoppe NOTICE. This message, together with any attachments, may contain privileged and/or confidential information. If you have received this e-mail in error or are not an intended recipient, you may not use, reproduce, disseminate or distribute it; do not open nor save any attachments, delete it immediately from your system and notify the sender promptly by e-mail that you have done so. Thank you. P Please consider the environment before printing this email -----Original Message----- From: Denninghoff, Sven Dr. (External) Sent: Tuesday, August 03, 2010 1:17 PM To: Berger, Lutz (External); Breiter, Stephan (External); Maehner, Herbert (External) Cc: Laine, Waldemar Subject: FW: FW: mq_open FYI -----Original Message----- From: Jan Blunck [mailto:jblunck(a)suse.de] Sent: Tuesday, August 03, 2010 11:02 AM To: Denninghoff, Sven Dr. (External) Subject: Re: FW: mq_open On Thu, Jul 29, Denninghoff, Sven Dr. (External) wrote: > Hallo Jan, > > > ich habe hier immer noch ein Problem mit Semaphoren und den > Messagequeues. Leider kann ich Dich nicht erreichen, ich h�tte auch > ein paar andere Fragen, z.B. bez�glich des HZ-paramters im Kernel. > Sorry, dass ich im Moment so schlecht erreichbar bin. Welche Probleme habt ihr mit den HZ settings? Hier mein Feedback zum mq_open() Problem: As the manpage of mq_open(3) states, the mode argument is used as for open(2). As it is described in the manpage for open(2) the mode argument is affected by the umask: "The argument mode specifies the permissions to use in case a new file is created. It is modified by the process's umask in the usual way: the permissions of the created file are (mode & ~umask)." So I would recommend the following code to create 0660 mode message queues: mqdes = mq_open(...); if (fchmod(mqdes, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP) == -1) abort(); Changing the umask would affect the creation of all other files as well. Be aware that this (using fchmod() on the mq descriptor) is a Linux specific extension (as stated in mq_overview(7)). On other UNIX's you probably need to still change the umask. Cheers, Jan > Gr��e > > Sven > > > ______________________________________________ > > From: Denninghoff, Sven Dr. (External) > > Sent: Tuesday, June 15, 2010 12:05 PM > > To: 'Jan Blunck' > > Subject: FW: mq_open > > > > Hallo Jan, > > > > kannst Du das nachvollziehen? Soll ich damit einen Bugrequest beim Support machen? > > > > Gr��e > > > > Sven > > > > > > ______________________________________________ > > From: Berger, Lutz (External) > > Sent: Tuesday, June 15, 2010 8:08 AM > > To: Denninghoff, Sven Dr. (External) > > Cc: Breiter, Stephan (External); Maehner, Herbert (External) > > Subject: mq_open > > > > Hello Sven, > > > > There is maybe a bug or a wrong understanding of mq_open: > > > > #include <mqueue.h <http://linux.die.net/include/mqueue.h> > mqd_t > > mq_open(const char *name, int oflag);mqd_t mq_open(const char *name, > > int oflag, mode_t mode, struct mq_attr *attr); > > > > if the paremeter "mode" is 0666, and "oflag" is "O_CREATE | O_RDWR" I expect that others users should be able to send message in this message queue. But then comes the error conde: permission denied. > > If /dev/mqueue is mounted, the permissions on the created message queue are rw-r--r-- not as expected rw-rw-rw as expected according to the mode parameter. > > If the permisions are manualy changed on the filesystem, other use can send messages. > > > > The behaviour is same in Open Suse 11.2 as on Suse Enterprise 11.0. > > > > If required, a small sample program can be provided, but is has to be taken out from the RIG. > > > > Thanks in advance. > > > > > > Mit freundlichen Gr��en / With best regards Lutz Berger > > > > EADS Deutschland GmbH > > Military Air Systems > > Integrated Team ASTA - MSF1 > > 85077 Manching > > Telephone: +49 (0) 8459.81-79443 > > Fax: +49 (0) 8459.81-66992 > > Mobile: +49 (0) 172.8223258 > > e-Mail: lutz.berger.external(a)eads.com > > <mailto:lutz.berger.external(a)eads.com?subject=%23> > > > > www.eads.com > > > > EADS Deutschland GmbH > > Registered Office: Ottobrunn > > District Court of Munich HRB 107 648 Chairman of the Supervisory > > Board: Dr. Thomas Enders Managing Directors: Dr. Stefan Zoller > > (chairman), Dr. Christoph Hoppe > > > > NOTICE. This message, together with any attachments, may contain > > privileged and/or confidential information. If you have received > > this e-mail in error or are not an intended recipient, you may not > > use, reproduce, disseminate or distribute it; do not open nor save > > any attachments, delete it immediately from your system and notify > > the sender promptly by e-mail that you have done so. > > > > Thank you. > > > > P Please consider the environment before printing this email > > > > Regards, Jan -- Jan Blunck <jblunck(a)suse.de> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Andi Kleen on 6 Aug 2010 06:40
"Berger, Lutz (External)" <Lutz.Berger.External(a)eads.com> writes: > > Hello gentleman, > > we have a problem with > mq_open, shm_open and sem_open > > As stated in the manpage of "open(2)", the > permissions of the created file are (mode & ~umask). > > But what is the use of the mode parameter, it it is not used like the programmers intention? > On HP Unix or TRU64 the mode parameter is not modified. > > Could you please check, if this is a bug or a faulty system design on linux? Whatever it is -- it would be dangerous to change because suddenly ignoring umask could add security problems to existing software. -Andi -- ak(a)linux.intel.com -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |