Bug#806882: libc-bin: unable to set pts permissions (and open a terminal...)

[Aurelien Jarno <aurelien@aurel32.net>]

On 2015-12-02 13:45, Domenico Andreoli wrote:
> Package: libc-bin
> Version: 2.21-1
> 
> Hi,
> 
>   I'm unable to open some terminal applications like rxvt and konsole,
> don't know why but xterm still works.
> 
> Running rxvt gives this output:
> 
> $ rxvt
> rxvt: can't open pseudo-tty
> rxvt: aborting
> $ strace rxvt
> statfs("/dev/pts", {f_type="DEVPTS_SUPER_MAGIC", f_bsize=4096, f_blocks=0,
> f_bfree=0, f_bavail=0, f_files=0, f_ffree=0, f_fsid={0, 0}, f_namelen=255,
> f_frsize=4096}) = 0
> ioctl(4, TCGETS, {B38400 opost isig icanon echo ...}) = 0
> ioctl(4, TIOCGPTN, [2])                 = 0
> stat("/dev/pts/2", {st_mode=S_IFCHR|0600, st_rdev=makedev(136, 2), ...}) = 0
> getuid()                                = 1000
> open("/etc/group", O_RDONLY|O_CLOEXEC)  = 5
> lseek(5, 0, SEEK_CUR)                   = 0
> fstat(5, {st_mode=S_IFREG|0644, st_size=624, ...}) = 0
> mmap(NULL, 624, PROT_READ, MAP_SHARED, 5, 0) = 0x7f02d0366000
> lseek(5, 624, SEEK_SET)                 = 624
> munmap(0x7f02d0366000, 624)             = 0
> close(5)                                = 0
> chown("/dev/pts/2", 1000, 5)            = -1 EPERM (Operation not permitted)
> close(4)                                = 0
> open("/dev/pty??", O_RDWR|O_NOCTTY)     = -1 ENOENT (No such file or
> directory)
> write(2, "rxvt: ", 6rxvt: )                   = 6
> write(2, "can't open pseudo-tty", 21can't open pseudo-tty)   = 21
> write(2, "\n", 1
> )
> $ ls -l /dev/pts/*
> crw------- 1 cavok cavok 136, 0 Dec  2  2015 /dev/pts/0
> crw------- 1 cavok cavok 136, 1 Dec  2 12:38 /dev/pts/1
> 
> Investigating konsole, the issue looks the same: unable to set pts
> permission.
> 
> Downgrading libc6 and libc6-i686 to 2.19-22 doesn't help, but downgrading
> libc-bin actually does the trick.
> 
> Could you please help here?

This is due to the changes introduced to fix the bug #717544. Your
system is supposed to have /dev/pts mounted with some options:

  devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)

This should be the default and can be modified in /etc/default/devpts.
It looks like in your case /dev/pts is not mounted or mounted with the
wrong options. Can you send the output of the following command:

  mount | grep devpts

Thanks,
Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                 http://www.aurel32.net