Re: [PATCH 2/2] ppc: kvm: use anon_inode_getfd() with O_CLOEXEC flag
Il 26/08/2013 10:23, Yann Droneaud ha scritto: > > Sounds a lot like InfiniBand subsystem behavor: IB file descriptors > are of no use accross exec() since memory mappings tied to those fds > won't be available in the new process: > > https://lkml.org/lkml/2013/7/8/380 > http://mid.gmane.org/f58540dc64fec1ac0e496dfcd3cc1...@meuh.org Yes, it is very similar. Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/2] ppc: kvm: use anon_inode_getfd() with O_CLOEXEC flag
Le 26.08.2013 09:39, Paolo Bonzini a écrit : Il 25/08/2013 17:04, Alexander Graf ha scritto: On 24.08.2013, at 21:14, Yann Droneaud wrote: This patch set O_CLOEXEC flag on all file descriptors created with anon_inode_getfd() to not leak file descriptors across exec(). Signed-off-by: Yann Droneaud Link: http://lkml.kernel.org/r/cover.1377372576.git.ydrone...@opteya.com Reviewed-by: Alexander Graf Would it make sense to simply inherit the O_CLOEXEC flag from the parent kvm fd instead? That would give user space the power to keep fds across exec() if it wants to. Does it make sense to use non-O_CLOEXEC file descriptors with KVM at all? Besides fork() not being supported by KVM, as described in Documentation/virtual/kvm/api.txt, the VMAs of the parent process go away as soon as you exec(). I'm not sure how you can use the inherited file descriptor in a sensible way after exec(). Sounds a lot like InfiniBand subsystem behavor: IB file descriptors are of no use accross exec() since memory mappings tied to those fds won't be available in the new process: https://lkml.org/lkml/2013/7/8/380 http://mid.gmane.org/f58540dc64fec1ac0e496dfcd3cc1...@meuh.org Regards. -- Yann Droneaud OPTEYA -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/2] ppc: kvm: use anon_inode_getfd() with O_CLOEXEC flag
Il 25/08/2013 17:04, Alexander Graf ha scritto: > > On 24.08.2013, at 21:14, Yann Droneaud wrote: > >> KVM uses anon_inode_get() to allocate file descriptors as part >> of some of its ioctls. But those ioctls are lacking a flag argument >> allowing userspace to choose options for the newly opened file descriptor. >> >> In such case it's advised to use O_CLOEXEC by default so that >> userspace is allowed to choose, without race, if the file descriptor >> is going to be inherited across exec(). >> >> This patch set O_CLOEXEC flag on all file descriptors created >> with anon_inode_getfd() to not leak file descriptors across exec(). >> >> Signed-off-by: Yann Droneaud >> Link: http://lkml.kernel.org/r/cover.1377372576.git.ydrone...@opteya.com > > Reviewed-by: Alexander Graf > > Would it make sense to simply inherit the O_CLOEXEC flag from the > parent kvm fd instead? That would give user space the power to keep > fds across exec() if it wants to. Does it make sense to use non-O_CLOEXEC file descriptors with KVM at all? Besides fork() not being supported by KVM, as described in Documentation/virtual/kvm/api.txt, the VMAs of the parent process go away as soon as you exec(). I'm not sure how you can use the inherited file descriptor in a sensible way after exec(). Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/2] ppc: kvm: use anon_inode_getfd() with O_CLOEXEC flag
Il 25/08/2013 17:04, Alexander Graf ha scritto: On 24.08.2013, at 21:14, Yann Droneaud wrote: KVM uses anon_inode_get() to allocate file descriptors as part of some of its ioctls. But those ioctls are lacking a flag argument allowing userspace to choose options for the newly opened file descriptor. In such case it's advised to use O_CLOEXEC by default so that userspace is allowed to choose, without race, if the file descriptor is going to be inherited across exec(). This patch set O_CLOEXEC flag on all file descriptors created with anon_inode_getfd() to not leak file descriptors across exec(). Signed-off-by: Yann Droneaud ydrone...@opteya.com Link: http://lkml.kernel.org/r/cover.1377372576.git.ydrone...@opteya.com Reviewed-by: Alexander Graf ag...@suse.de Would it make sense to simply inherit the O_CLOEXEC flag from the parent kvm fd instead? That would give user space the power to keep fds across exec() if it wants to. Does it make sense to use non-O_CLOEXEC file descriptors with KVM at all? Besides fork() not being supported by KVM, as described in Documentation/virtual/kvm/api.txt, the VMAs of the parent process go away as soon as you exec(). I'm not sure how you can use the inherited file descriptor in a sensible way after exec(). Paolo -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/2] ppc: kvm: use anon_inode_getfd() with O_CLOEXEC flag
Le 26.08.2013 09:39, Paolo Bonzini a écrit : Il 25/08/2013 17:04, Alexander Graf ha scritto: On 24.08.2013, at 21:14, Yann Droneaud wrote: This patch set O_CLOEXEC flag on all file descriptors created with anon_inode_getfd() to not leak file descriptors across exec(). Signed-off-by: Yann Droneaud ydrone...@opteya.com Link: http://lkml.kernel.org/r/cover.1377372576.git.ydrone...@opteya.com Reviewed-by: Alexander Graf ag...@suse.de Would it make sense to simply inherit the O_CLOEXEC flag from the parent kvm fd instead? That would give user space the power to keep fds across exec() if it wants to. Does it make sense to use non-O_CLOEXEC file descriptors with KVM at all? Besides fork() not being supported by KVM, as described in Documentation/virtual/kvm/api.txt, the VMAs of the parent process go away as soon as you exec(). I'm not sure how you can use the inherited file descriptor in a sensible way after exec(). Sounds a lot like InfiniBand subsystem behavor: IB file descriptors are of no use accross exec() since memory mappings tied to those fds won't be available in the new process: https://lkml.org/lkml/2013/7/8/380 http://mid.gmane.org/f58540dc64fec1ac0e496dfcd3cc1...@meuh.org Regards. -- Yann Droneaud OPTEYA -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/2] ppc: kvm: use anon_inode_getfd() with O_CLOEXEC flag
Il 26/08/2013 10:23, Yann Droneaud ha scritto: Sounds a lot like InfiniBand subsystem behavor: IB file descriptors are of no use accross exec() since memory mappings tied to those fds won't be available in the new process: https://lkml.org/lkml/2013/7/8/380 http://mid.gmane.org/f58540dc64fec1ac0e496dfcd3cc1...@meuh.org Yes, it is very similar. Paolo -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/2] ppc: kvm: use anon_inode_getfd() with O_CLOEXEC flag
On 24.08.2013, at 21:14, Yann Droneaud wrote: > KVM uses anon_inode_get() to allocate file descriptors as part > of some of its ioctls. But those ioctls are lacking a flag argument > allowing userspace to choose options for the newly opened file descriptor. > > In such case it's advised to use O_CLOEXEC by default so that > userspace is allowed to choose, without race, if the file descriptor > is going to be inherited across exec(). > > This patch set O_CLOEXEC flag on all file descriptors created > with anon_inode_getfd() to not leak file descriptors across exec(). > > Signed-off-by: Yann Droneaud > Link: http://lkml.kernel.org/r/cover.1377372576.git.ydrone...@opteya.com Reviewed-by: Alexander Graf Would it make sense to simply inherit the O_CLOEXEC flag from the parent kvm fd instead? That would give user space the power to keep fds across exec() if it wants to. Alex -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/2] ppc: kvm: use anon_inode_getfd() with O_CLOEXEC flag
On 24.08.2013, at 21:14, Yann Droneaud wrote: KVM uses anon_inode_get() to allocate file descriptors as part of some of its ioctls. But those ioctls are lacking a flag argument allowing userspace to choose options for the newly opened file descriptor. In such case it's advised to use O_CLOEXEC by default so that userspace is allowed to choose, without race, if the file descriptor is going to be inherited across exec(). This patch set O_CLOEXEC flag on all file descriptors created with anon_inode_getfd() to not leak file descriptors across exec(). Signed-off-by: Yann Droneaud ydrone...@opteya.com Link: http://lkml.kernel.org/r/cover.1377372576.git.ydrone...@opteya.com Reviewed-by: Alexander Graf ag...@suse.de Would it make sense to simply inherit the O_CLOEXEC flag from the parent kvm fd instead? That would give user space the power to keep fds across exec() if it wants to. Alex -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
