I see. Thank you for the feedback. I will rework changes to get back read permissions.
Best regards, Petro пт, 28 січ. 2022 р. о 14:41 Alan Carvalho de Assis <acas...@gmail.com> пише: > > Hi Petro, > > The read permission is needed even when you just want to open a file: > > $ vim noreadfile > > $ chmod 0000 noreadfile > > $ ls -l noreadfile > ---------- 1 user user 5 jan 28 09:24 noreadfile > > $ cat noreadfile > cat: noreadfile: Permission denied > > You can even try to create a C program just to open it, and it will fail. > > See the man page of open function: > > The argument flags *must* include one of the following access > modes: O_RDONLY, O_WRONLY, or > O_RDWR. These request opening the file read-only, write-only, > or read/write, respectively. > > This man page makes it clear you must include an access mode, but I > passed 0 to the access mode flag of open() and it was accepted, but > when the file has permission 0000 it returns -EPERM: "Failed to open > file: error -1" > > BR, > > Alan > > On 1/28/22, Petro Karashchenko <petro.karashche...@gmail.com> wrote: > > Hello, > > > > Yes, but how does this relate to "0000" mode for "register_driver()"? > > Maybe you can describe some use case so it will become more clear? > > Currently ioctl works fine if driver is registered with "0000" permission > > mode. > > > > Best regards, > > Petro > > > > пт, 28 січ. 2022 р. о 11:39 Xiang Xiao <xiaoxiang781...@gmail.com> пише: > >> > >> If we want to do the correct permission check, the ioctl handler needs to > >> check R/W bit by itself based on how the ioctl is implemented. > >> Or follow up how Linux encode the needed permission into each IOCTL: > >> https://github.com/torvalds/linux/blob/master/include/uapi/asm-generic/ioctl.h#L85-L91 > >> and let's VFS layer do the check for each driver. > >> > >> On Fri, Jan 28, 2022 at 5:14 PM Petro Karashchenko < > >> petro.karashche...@gmail.com> wrote: > >> > >> > Hello team, > >> > > >> > Recently I have noticed that there are many places in code where > >> > register_driver() is called with non-zero mode with file operation > >> > structures that have neither read nor write APIs implemented. For > >> > example "ret = register_driver(path, &opamp_fops, 0444, dev);" while > >> > opamp_fops has only "opamp_open", "opamp_close" and "opamp_ioctl" > >> > implemented. I made a PR to fix it > >> > https://github.com/apache/incubator-nuttx/pull/5347 and change mode > >> > from "0444" to "0000", but want to ask if anyone sees any drawback in > >> > such an approach? Maybe I'm missing something? > >> > > >> > Best regards, > >> > Petro > >> > > >
