Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c

[Blue Swirl]

On Wed, Jun 13, 2012 at 8:30 PM, Daniel P. Berrange <address@hidden> wrote:
> On Wed, Jun 13, 2012 at 04:20:22PM -0300, Eduardo Otubo wrote:
>> I added a syscall struct using priority levels as described in the
>> libseccomp man page. The priority numbers are based to the frequency
>> they appear in a sample strace from a regular qemu guest run under
>> libvirt.
>>
>> Libseccomp generates linear BPF code to filter system calls, those rules
>> are read one after another. The priority system places the most common
>> rules first in order to reduce the overhead when processing them.
>>
>> Also, since this is just a first RFC, the whitelist is a little raw. We
>> might need your help to improve, test and fine tune the set of system
>> calls.
>>
>> v2: Fixed some style issues
>>       Removed code from vl.c and created qemu-seccomp.[ch]
>>       Now using ARRAY_SIZE macro
>>       Added more syscalls without priority/frequency set yet
>>
>> Signed-off-by: Eduardo Otubo <address@hidden>
>> ---
>>  qemu-seccomp.c |   73 
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>  qemu-seccomp.h |    9 +++++++
>>  vl.c           |    7 ++++++
>>  3 files changed, 89 insertions(+)
>>  create mode 100644 qemu-seccomp.c
>>  create mode 100644 qemu-seccomp.h
>>
>> diff --git a/qemu-seccomp.c b/qemu-seccomp.c
>> new file mode 100644
>> index 0000000..048b7ba
>> --- /dev/null
>> +++ b/qemu-seccomp.c
>> @@ -0,0 +1,73 @@
>> +#include <stdio.h>
>> +#include <seccomp.h>
>> +#include "qemu-seccomp.h"
>> +
>> +static struct QemuSeccompSyscall seccomp_whitelist[] = {
>> +    { SCMP_SYS(timer_settime), 255 },
>> +    { SCMP_SYS(timer_gettime), 254 },
>> +    { SCMP_SYS(futex), 253 },
>> +    { SCMP_SYS(select), 252 },
>> +    { SCMP_SYS(recvfrom), 251 },
>> +    { SCMP_SYS(sendto), 250 },
>> +    { SCMP_SYS(read), 249 },
>> +    { SCMP_SYS(brk), 248 },
>> +    { SCMP_SYS(clone), 247 },
>> +    { SCMP_SYS(mmap), 247 },
>> +    { SCMP_SYS(mprotect), 246 },
>> +    { SCMP_SYS(ioctl), 245 },
>> +    { SCMP_SYS(recvmsg), 245 },
>> +    { SCMP_SYS(sendmsg), 245 },
>> +    { SCMP_SYS(accept), 245 },
>> +    { SCMP_SYS(connect), 245 },
>> +    { SCMP_SYS(bind), 245 },
>> +    { SCMP_SYS(listen), 245 },
>> +    { SCMP_SYS(ioctl), 245 },
>> +    { SCMP_SYS(eventfd), 245 },
>> +    { SCMP_SYS(rt_sigprocmask), 245 },
>> +    { SCMP_SYS(write), 244 },
>> +    { SCMP_SYS(fcntl), 243 },
>> +    { SCMP_SYS(tgkill), 242 },
>> +    { SCMP_SYS(rt_sigaction), 242 },
>> +    { SCMP_SYS(pipe2), 242 },
>> +    { SCMP_SYS(munmap), 242 },
>> +    { SCMP_SYS(mremap), 242 },
>> +    { SCMP_SYS(getsockname), 242 },
>> +    { SCMP_SYS(getpeername), 242 },
>> +    { SCMP_SYS(fdatasync), 242 },
>> +    { SCMP_SYS(close), 242 }
>
> execve(), so QEMU can run things like the ifup/down
> scripts, the samba daemon (sic), exec: migration protocol,
> etc, etc

I think allowing execve() would render seccomp pretty much useless.

>
>
> Daniel
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