commit 2d3904aba67e79e57db1814033b1df3f77336065 Author: Nick Mathewson <nickm@torproject.org> Date: Thu Nov 16 14:06:38 2017 -0500 Check the libc version to decide whether to allow openat. --- configure.ac | 2 ++ src/common/sandbox.c | 38 +++++++++++++++++++++++++++++++++++++- 2 files changed, 39 insertions(+), 1 deletion(-) diff --git a/configure.ac b/configure.ac index f2c3f90ba..3ff819052 100644 --- a/configure.ac +++ b/configure.ac @@ -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 \ diff --git a/src/common/sandbox.c b/src/common/sandbox.c index 417c1e305..d0ead2cae 100644 --- a/src/common/sandbox.c +++ b/src/common/sandbox.c @@ -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);