On Wed, Jun 13, 2012 at 7:20 PM, Eduardo Otubo <ot...@linux.vnet.ibm.com> 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 <ot...@linux.vnet.ibm.com> > --- > 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 @@
Copyright and license info missing. > +#include <stdio.h> > +#include <seccomp.h> > +#include "qemu-seccomp.h" > + > +static struct QemuSeccompSyscall seccomp_whitelist[] = { 'const' > + { 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 }, It would be nice to avoid connect() and bind(). Perhaps seccomp init should be postponed to after all sockets have been created? > + { 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 } > +}; > + > +#define seccomp_whitelist_count ARRAY_SIZE(seccomp_whitelist) I'm not sure the #define helps much. > + > +int seccomp_start(void) > +{ > + int rc = 0; > + unsigned int i = 0; > + > + rc = seccomp_init(SCMP_ACT_KILL); > + if (rc < 0) { > + goto seccomp_return; > + } > + > + for (i = 0; i < seccomp_whitelist_count; i++) { > + rc = seccomp_rule_add(SCMP_ACT_ALLOW, seccomp_whitelist[i].num, 0); > + if (rc < 0) { > + goto seccomp_return; > + } > + rc = seccomp_syscall_priority(seccomp_whitelist[i].num, > + seccomp_whitelist[i].priority); > + if (rc < 0) { > + goto seccomp_return; > + } > + } > + > + rc = seccomp_load(); > + > + seccomp_return: > + seccomp_release(); > + if (rc < 0) { > + fprintf(stderr, > + "ERROR: failed to configure the seccomp syscall filter in > the kernel\n"); Should this be fatal? > + } > + return rc; Return value is not used. > +} > diff --git a/qemu-seccomp.h b/qemu-seccomp.h > new file mode 100644 > index 0000000..3bbdd87 > --- /dev/null > +++ b/qemu-seccomp.h > @@ -0,0 +1,9 @@ Usual header protection #ifndeffery missing. > +#include <seccomp.h> > +#include "osdep.h" > + > +struct QemuSeccompSyscall { > + int32_t num; > + uint8_t priority; > +}; This definition is not used elsewhere, so it should be internal to qemu-seccomp.c. > + > +int seccomp_start(void); > diff --git a/vl.c b/vl.c > index 204d85b..315afaf 100644 > --- a/vl.c > +++ b/vl.c > @@ -61,6 +61,9 @@ > > #include <linux/ppdev.h> > #include <linux/parport.h> > +#ifdef CONFIG_LIBSECCOMP > +#include "qemu-seccomp.h" > +#endif > #endif > #ifdef __sun__ > #include <sys/stat.h> > @@ -2296,6 +2299,10 @@ int main(int argc, char **argv, char **envp) > const char *trace_events = NULL; > const char *trace_file = NULL; > > +#ifdef CONFIG_LIBSECCOMP > + seccomp_start(); > +#endif > + > atexit(qemu_run_exit_notifiers); > error_set_progname(argv[0]); > > -- > 1.7.9.5 > >