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SubjectRe: [ 42/68] vfs: make O_PATH file descriptors usable for fchdir()
From
Just to be sure, has any one tested the patch (I can't, I am not doing
Linux kernel development and the closest here to me here only does
Solaris/Illumos and SUPERUX kernel development)?

My test case, which works on Solaris and AIX is below. You will have
to do a s/O_SEARCH/O_PATH/
-------- snip --------
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

int main(int ac, char *av[])
{
int dirfd, dupdirfd;
dirfd=open("/etc", O_SEARCH);
if(dirfd<0)
{
fprintf(stderr, "open() failed.\n");
return EXIT_FAILURE;
}
dupdirfd = fcntl(dirfd, F_DUPFD, 50);
if(dirfd<0)
{
fprintf(stderr, "fcntl() failed.\n");
return EXIT_FAILURE;
}
if(fchdir(dupdirfd)<0)
{
fprintf(stderr, "fchdir(dupdirfd) failed.\n");
return EXIT_FAILURE;
}
if(fchdir(dirfd)<0)
{
fprintf(stderr, "fchdir(dirfd) failed.\n");
return EXIT_FAILURE;
}
if(openat(dupdirfd, "profile", O_RDONLY)<0)
{
fprintf(stderr, "openat(dupdirfd, profile, O_RDONLY) failed.\n");
return EXIT_FAILURE;
}
dirfd=openat(dupdirfd, "krb5", O_SEARCH);
if(dirfd<0)
{
fprintf(stderr, "openat(dupdirfd, krb5, O_SEARCH) failed.\n");
return EXIT_FAILURE;
}
if(fchdir(dirfd)<0)
{
fprintf(stderr, "2nd fchdir(dirfd) failed.\n");
return EXIT_FAILURE;
}
puts("SUCCESS.");

return EXIT_SUCCESS;
}
-------- snip --------
Olga

On Thu, Jul 12, 2012 at 7:51 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> 3.0-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Linus Torvalds <torvalds@linux-foundation.org>
>
> commit 332a2e1244bd08b9e3ecd378028513396a004a24 upstream.
>
> We already use them for openat() and friends, but fchdir() also wants to
> be able to use O_PATH file descriptors. This should make it comparable
> to the O_SEARCH of Solaris. In particular, O_PATH allows you to access
> (not-quite-open) a directory you don't have read persmission to, only
> execute permission.
>
> Noticed during development of multithread support for ksh93.
>
> Reported-by: ольга крыжановская <olga.kryzhanovska@gmail.com>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> ---
> fs/open.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -396,10 +396,10 @@ SYSCALL_DEFINE1(fchdir, unsigned int, fd
> {
> struct file *file;
> struct inode *inode;
> - int error;
> + int error, fput_needed;
>
> error = -EBADF;
> - file = fget(fd);
> + file = fget_raw_light(fd, &fput_needed);
> if (!file)
> goto out;
>
> @@ -413,7 +413,7 @@ SYSCALL_DEFINE1(fchdir, unsigned int, fd
> if (!error)
> set_fs_pwd(current->fs, &file->f_path);
> out_putf:
> - fput(file);
> + fput_light(file, fput_needed);
> out:
> return error;
> }
>
>



--
, _ _ ,
{ \/`o;====- Olga Kryzhanovska -====;o`\/ }
.----'-/`-/ olga.kryzhanovska@gmail.com \-`\-'----.
`'-..-| / http://twitter.com/fleyta \ |-..-'`
/\/\ Solaris/BSD//C/C++ programmer /\/\
`--` `--`
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