What is the difference between 'login: root' and 'su -' ?

What is the difference between 'login: root' and 'su -' ?

Post by Peter Seidere » Fri, 09 Nov 2001 18:00:19



Hello,
first thank you for your effort.

Did the diff: nearly no difference till the failure point (only pid, time etc.).
Peter


> On Thu, Nov 08, 2001 at 09:46:37AM +0100, you [Peter Seiderer] claimed:
> > Hello,
> > in both cases file descriptor 4 is from 'open("/dev/hdc4", O_RDWR) = 4'  ....
> > Peter

> Well, beats me. Sorry I wasn't much of a help...

> One thing you could try is to capture the strace output of both sessions up
> to the point where the 'su -' one fails. Then do a diff for those logs and
> see if anything suspicios differs. Not much _should_ differ, I reckon...

> -- v --



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What is the difference between 'login: root' and 'su -' ?

Post by PVotr.. » Sat, 10 Nov 2001 00:10:15


Hi,

BTW, /dev/hdc4, is that a regular hard disk partition? I was always used to
create /dev/hda1, /dev/hda5, /dev/hda6 etc.  as normal partitions (via
fdisk).

Is your /dev/hda hard disk drive or some other device?

Just for my curiosity :)

Regards
Petr

> -----Pvodn zprva-----

> Odeslno: 8. listopadu 2001 9:47

> Kopie:     Ville Herva
> P?edmt: Re: What is the difference between 'login: root' and 'su -'
> ?

> Hello,
> in both cases file descriptor 4 is from 'open("/dev/hdc4", O_RDWR) = 4'
> ....
> Peter


> > On Wed, Nov 07, 2001 at 11:40:25PM +0100, you [Peter Seiderer] claimed:
> > > Mhhh,
> > > the strace output from the 'login: root' one (the one which was good)
> > > looks the same till the EFBIG place:

> > >  write(1, "\10\10\10\10\10", 5)          = 5
> > >  write(1, "16/44", 5)                    = 5
> > >  _llseek(4, 18446744071562084352, [2147500032], SEEK_SET) = 0
> > >  write(4,
> "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 32768) =
> 32768
> > >  _llseek(4, 18446744071562117120, [2147532800], SEEK_SET) = 0
> > >  write(4,
> "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 32768) =
> 32768
> > >  _llseek(4, 18446744071562149888, [2147565568], SEEK_SET) = 0
> > >  write(4,
> "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 32768) =
> 32768
> > >  _llseek(4, 18446744071562182656, [2147598336], SEEK_SET) = 0
> > >  write(4,
> "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 32768) =
> 32768

> > Weird. Perhaps strace gets that wrong and the problem is elsewhere.

> > Did you make sure that fd 4 is the same _partition_ in both cases (using
> > strace)? The only thing I could imagine exposing 2GB limit is writing to
> a
> > file.

> > > > >        zodiak login: seiderer
> > > > >        Password:

> > > > >        Password:
> > > > >        zodiak:~ #
> > > > >        zodiak:~ # mkfs.ext2 /dev/hdc4
> > > > >        mke2fs 1.18, 11-Nov-1999 for EXT2 FS 0.5b, 95/08/09
> > > > >        Filesystem label=
> > > > >        OS type: Linux
> > > > >        Block size=4096 (log=2)
> > > > >        Fragment size=4096 (log=2)
> > > > >        716672 inodes, 1432116 blocks
> > > > >        71605 blocks (5.00%) reserved for the super user
> > > > >        First data block=0
> > > > >        44 block groups
> > > > >        32768 blocks per group, 32768 fragments per group
> > > > >        16288 inodes per group
> > > > >        Superblock backups stored on blocks:
> > > > >                32768, 98304, 163840, 229376, 294912, 819200, 884736

> > > > >        Writing inode tables: 16/44File size limit exceeded

> > > > > strace showed that write returned wit EFBIG and the process ended
> with SIGXFSZ:

> > > > >        write(1, "\10\10\10\10\10", 5)          = 5
> > > > >        write(1, "16/44", 5)                    = 5
> > > > >        _llseek(4, 18446744071562084352, [2147500032], SEEK_SET) = 0
> > > > >        write(4,
> "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 32768) = -1
> EFBIG (File too large)
> > > > >        --- SIGXFSZ (File size limit exceeded) ---
> > > > >        +++ killed by SIGXFSZ +++

> > > > Hmm, 18446744071562084352 = 0xffffffff80004000, 2147500032 =
> 0x80004000...
> > > > It looks a tad like llseek's offset_high would have been
> corrupted...
> > > > Strange.

> > > > 1432116 blocks * 4096 bytes/block * 16/44 written = 2133071685.81818
> so
> > > > 2147500032 looks sane(ish).

> > -- v --


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