Commit 2d3904ab authored by Nick Mathewson's avatar Nick Mathewson 🦀
Browse files

Check the libc version to decide whether to allow openat.

parent d2d6a1b0

configure.ac

+2 −0
Original line number Diff line number Diff line
@@ -390,6 +390,7 @@ AC_CHECK_FUNCS( 
        getrlimit \

        gettimeofday \

        gmtime_r \

	gnu_get_libc_version \

	htonll \

        inet_aton \

        ioctl \
@@ -1011,6 +1012,7 @@ AC_CHECK_HEADERS([assert.h \ 
                  arpa/inet.h \

                  crt_externs.h \

                  execinfo.h \

                  gnu/libc-version.h \

                  grp.h \

                  ifaddrs.h \

                  inttypes.h \

src/common/sandbox.c

+37 −1
Original line number Diff line number Diff line
@@ -56,6 +56,9 @@ 
#include <time.h>

#include <poll.h>



#ifdef HAVE_GNU_LIBC_VERSION_H

#include <gnu/libc-version.h>

#endif

#ifdef HAVE_LINUX_NETFILTER_IPV4_H

#include <linux/netfilter_ipv4.h>

#endif
@@ -424,6 +427,37 @@ sb_mmap2(scmp_filter_ctx ctx, sandbox_cfg_t *filter) 
}

#endif



#ifdef HAVE_GNU_LIBC_VERSION_H

#ifdef HAVE_GNU_GET_LIBC_VERSION

#define CHECK_LIBC_VERSION

#endif

#endif



/* Return true if we think we're running with a libc that always uses

 * openat on linux. */

static int

libc_uses_openat_for_everything(void)

{

#ifdef CHECK_LIBC_VERSION

  const char *version = gnu_get_libc_version();

  if (version == NULL)

    return 0;



  int major = -1;

  int minor = -1;



  tor_sscanf(version, "%d.%d", &major, &minor);

  if (major >= 3)

    return 1;

  else if (major == 2 && minor >= 26)

    return 1;

  else

    return 0;

#else

  return 0;

#endif

}



/** Allow a single file to be opened.  If <b>use_openat</b> is true,

 * we're using a libc that remaps all the opens into openats. */

static int
@@ -449,13 +483,15 @@ sb_open(scmp_filter_ctx ctx, sandbox_cfg_t *filter) 
  int rc;

  sandbox_cfg_t *elem = NULL;



  int use_openat = libc_uses_openat_for_everything();



  // for each dynamic parameter filters

  for (elem = filter; elem != NULL; elem = elem->next) {

    smp_param_t *param = elem->param;



    if (param != NULL && param->prot == 1 && param->syscall

        == SCMP_SYS(open)) {

      rc = allow_file_open(ctx, 0 /* XXXX */, param->value);

      rc = allow_file_open(ctx, use_openat, param->value);

      if (rc != 0) {

        log_err(LD_BUG,"(Sandbox) failed to add open syscall, received "

            "libseccomp error %d", rc);