2011/7/6 Javier Martinez Canillas <martinez.javier@xxxxxxxxx>: > 2011/7/6 Mandeep Sandhu <mandeepsandhu.chd@xxxxxxxxx>: >>> How would using sysfs be useful if we were to talk about interacting with, let's say, a file system? ioctl's are quite versatile and rather easy to use when one wants to interact with a given FS. >>> >>> For instance, one can manage a Btrfs file system by using an user-level tool, which heavily uses ioctl's. Requiring it to interact with sysfs instead seems like complicating something simple with no apparent purpose. >> > > Something that always has caught my attention is why netlink sockets > are so popular. I know that ioctl is deprecated and all new kernel > code that needs full-duplex communication between userspace and > kernelspace shoud use netlink as its interface. > > But one of the arguments against ioctl is that you don't have type > checking which makes really hard to audit the parameters passed from > userspace. Also ioctl can be provided by third party as modules (that > can also be proprietary binary only ones) which even complicates more > to have a general security mechanism. > > My question is, why netlink sockets are better than ioctls? It is not > yet another interface to use as a wildcard to pass any data you wan't > between the kernel and userpace with the only difference that you use > another paradigm? (network sockets with a specific protocol family > instead file operations over a device). > > Sorry if my question is stupid but I just don't get the point. > > Regards, > > -- > Javier Martínez Canillas > (+34) 682 39 81 69 > PhD Student in High Performance Computing > Computer Architecture and Operating System Department (CAOS) > Universitat Autònoma de Barcelona > Barcelona, Spain > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@xxxxxxxxxxxxxxxxx > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > Javier, I think the main issue with ioctl is that with some architectures, the userspace and kernel compiler treat 64-bit structure members differently, so it is very easy to create a structure which can not easily be passed via a simple pointer in-all-architectures. With netlink sockets, one is expected to have a well defined byte order coming across the socket. Greg _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
