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SubjectRe: NT vulnerable to attack on CPU

put a cronjob to run a bomb and this won't have any effect.
ie. linux limits (and prolly most unicees) are useless.
I'm prolly going to hack the kernel a bit to do the following:
certain limit for uid's < 1000
and certain limit for uid's > 1000 (users)

Andi

On Mon, 23 Dec 1996, Trevor Johnson wrote:

>
>
> bofh@snoopy.virtual.net.au wrote:
> > I have written and run test programs such as that and not had any problems.
> > Your oops indicates that there is some bug in process handling in the kernel
> > you are running. Other versions of the Linux kernel do not have this bug.
>
> Yes. When I ran the "wabbit" under 2.0.27, there were no oopses. The
> system slowed down greatly (to the point of being unusable) as the load
> average went up to 150 or so, but after I pressed control-c, everything
> returned to normal.
>
> > for users. So I could set my system up so that the following command would
> > result in fork failing if the user already has 20 or more processes:
> >#echo 20 > /proc/sys/procs-per-user
> >
> > What do you think?
>
> That sounds ideal.
>
> > It doesn't. Use lshell and it'll work for all shells.
>
> My /etc/lshell.conf has this:
>
> root - // No limits for root
> default C60P30D20F24 // Default limits, 60 min's CPU time, 30
> processes, 20Mb, 24 file descriptors
>
> but I haven't configured it to run. Instead, I'm using the shadow suite,
> and /etc/limits contained:
>
> # Format:
> # <username> <limits-string>
> #
> # default entry is '*' for username
> #
> # Valid flags are:
> # C: max core file size (KB)
> # D: max data size (KB)
> # F: maximum filesize (KB)
> # M: max locked-in-memory address space (KB)
> # N: max number of open files
> # R: max resident set size (KB)
> # S: max stack size (KB)
> # T: max CPU time (MIN)
> # U: max number of processes
> # L: max number of logins for this user
> #
> # the default entry
> #* L2 D6144 R2048 S2048 U32 N32 F16384 T5 C0
> L12 D8192 R16384 S4096 U32 N64 C0
> # another way of suspending a user login
> nobody L0
> # this account has no limits
> root -
>
> which was misconfigured (I'd forgotten the asterisk for the default
> entry), so the "limit" command in tcsh (from my own account) returned:
>
> cputime unlimited
> filesize 1048576 kbytes
> datasize unlimited
> stacksize 8192 kbytes
> coredumpsize 0 kbytes
> memoryuse unlimited
> descriptors 256
> memorylocked unlimited
> maxproc 256
>
> under 2.0.27. Under 2.1.17, it looks the same, except that I'd applied
> Jared Mauch's patch to fd.c and limits.h, increasing the number of open
> file descriptors to 512.
>
> After adding the asterisk to /etc/limits, I could run the fork bomb from
> my own account with no problems. The summary from "top":
>
> 11:56pm up 29 min, 2 users, load average: 24.30, 8.21, 3.69
> 52 processes: 20 sleeping, 32 running, 0 zombie, 0 stopped
> CPU states: 4.2% user, 95.6% system, 99.1% nice, 0.9% idle
> Mem: 62668K av, 12356K used, 50312K free, 10504K shrd, 872K buff
> Swap: 0K av, 0K used, 0K free 7300K cached
>
> Here's my configuration for 2.1.17:
>
> CONFIG_EXPERIMENTAL=y
> CONFIG_MODULES=y
> CONFIG_MODVERSIONS=y
> CONFIG_KERNELD=y
> CONFIG_NET=y
> CONFIG_PCI=y
> CONFIG_PCI_OPTIMIZE=y
> CONFIG_SYSVIPC=y
> CONFIG_BINFMT_AOUT=m
> CONFIG_BINFMT_ELF=y
> CONFIG_BINFMT_JAVA=m
> CONFIG_M486=y
> CONFIG_BLK_DEV_FD=m
> CONFIG_BLK_DEV_IDE=y
> CONFIG_BLK_DEV_IDEDISK=y
> CONFIG_BLK_DEV_LOOP=m
> CONFIG_INET=y
> CONFIG_PATH_MTU_DISCOVERY=y
> CONFIG_IP_NOSR=y
> CONFIG_IPV6=m
> CONFIG_LLC=y
> CONFIG_SCSI=m
> CONFIG_CHR_DEV_ST=m
> CONFIG_BLK_DEV_SR=m
> CONFIG_BLK_DEV_SR_VENDOR=y
> CONFIG_SCSI_CONSTANTS=y
> CONFIG_SCSI_AHA1542=m
> CONFIG_NETDEVICES=y
> CONFIG_NET_ETHERNET=y
> CONFIG_NET_ISA=y
> CONFIG_NE2000=m
> CONFIG_PPP=y
> CONFIG_SHAPER=m
> CONFIG_MINIX_FS=m
> CONFIG_EXT2_FS=y
> CONFIG_FAT_FS=y
> CONFIG_MSDOS_FS=m
> CONFIG_VFAT_FS=m
> CONFIG_UMSDOS_FS=m
> CONFIG_PROC_FS=y
> CONFIG_NFS_FS=m
> CONFIG_SMB_FS=m
> CONFIG_SMB_WIN95=y
> CONFIG_ISO9660_FS=m
> CONFIG_SERIAL=y
> CONFIG_PRINTER=m
> CONFIG_SOUND=m
> CONFIG_SB=y
> CONFIG_ADLIB=y
> CONFIG_YM3812=y
> CONFIG_LOWLEVEL_SOUND=y
> CONFIG_AWE32_SYNTH=y
> ___
> Trevor Johnson <trevor@jpj.net>
>
>
>
>


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