the nfs server is RedHat 4.2. It exports /usr and two tftpboot
directories, the two dir are very similar, and based on 4.2, not
identical though.
After that I did made an 34pre13 kernel and NET-booted it on
Cyrix686MMX-PR200 /w 64mb ram,
it appeared to work all fine, I could login as user etc.
Afrter that I netbooted it on
Cyrix486-66 w/ 8mb ram.
It would have exactly those symptom as other say:
I could login fine as user, but trying any of the following:
login : it would fail w/ "no home/foo directory" message
su : would say "/bin/bash permission denied"
trying to run a program which first setuid() and
then to ties to system("/bin/bash"), makes fork to fail.
[program attached below]
[root@bea /root]# su foo
su: cannot run /bin/bash: Permission denied
[root@bea /root]# whoami
root
[root@bea /root]# test3
[root@bea /root]# whoami
root
[root@bea /root]# telnet localhost
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Red Hat Linux Red Hat Linux release 4.2 (Biltmore)
Kernel 2.0.34 on an i486
login: foo
No directory /foo!
Connection closed by foreign host.
Note : kernels were identical, the /usr dir was identical,
the /tftpboot.<x> dirs are separate copies but
I think they are closely identical, and after all
they should not contribute to make system()
call to fail.
[root@eax root]# cat test3.c
#include<unistd.h>
#include<stdlib.h>
main () {
int err = setuid(500);
system("/bin/bash");
}
-Adam
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