[libvirt] [PATCH 2/2] virt-login-shell joins users into lxc container.

Daniel J Walsh dwalsh at redhat.com
Thu Jan 2 15:18:16 UTC 2014


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On 12/23/2013 05:44 PM, Eric Blake wrote:
> On 12/23/2013 03:17 PM, Eric Blake wrote:
> 
>>>> +    if (!(conf = virConfReadFile(login_shell_path, 0))) +	goto
>>>> cleanup;
>>> 
>>> ...and non-root invariably fails here, since login_shell_path 
>>> (/etc/libvirt/virt-login-shell.conf) is buried inside a directory that 
>>> is not searchable by either root or virtlogin.
>> 
>> Ah, I see - non-root fails here if run unprivileged (such as under gdb), 
>> but when run setuid it has the permissions of root and can read the file 
>> just fine.
> 
Maybe need to give it cap_dac_read_search?

/* Overrides all DAC restrictions regarding read and search on files
   and directories, including ACL restrictions if [_POSIX_ACL] is
   defined. Excluding DAC access covered by CAP_LINUX_IMMUTABLE. */

#define CAP_DAC_READ_SEARCH  2


> Then again, when run as setuid, it's not even getting past virInitialize().
> :(
> 
> At least I managed to figure out how to debug things: I recompiled with a
> sleep() at the beginning, gave my just-compiled binary the same setuid 
> permissions as the installed binary, and then attach gdb (as root, since 
> non-root can't ptrace a running setuid binary for obvious reasons).  So I
> suspect that the failure in virInitialize() is yet more fallout from the
> CVE-2013-4400 patches being untested.
> 

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