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Check the libc version to decide whether to allow openat.

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This commit is contained in:
Nick Mathewson 2017-11-16 14:06:38 -05:00
parent d2d6a1b082
commit 2d3904aba6
2 changed files with 39 additions and 1 deletions
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2
configure.ac
View File

@ -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 \

38
src/common/sandbox.c
View File

@ -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);