[tor-commits] [tor/master] fix for getaddrinfo open syscall

[nickm at torproject.org]

commit 36aeca0ecf5f6e724a4d5da1795c9c9d76410290
Author: Cristian Toader <cristian.matei.toader at gmail.com>
Date:   Mon Aug 19 13:56:50 2013 +0300

    fix for getaddrinfo open syscall
---
 src/common/address.c |    3 ++-
 src/common/sandbox.c |   72 +++++++++++++++++++++++++++++++++++++++++++-------
 src/common/sandbox.h |    4 +++
 3 files changed, 69 insertions(+), 10 deletions(-)

diff --git a/src/common/address.c b/src/common/address.c
index 227b4fb..5c8603e 100644
--- a/src/common/address.c
+++ b/src/common/address.c
@@ -14,6 +14,7 @@
 #include "address.h"
 #include "torlog.h"
 #include "container.h"
+#include "sandbox.h"
 
 #ifdef _WIN32
 #include <process.h>
@@ -234,7 +235,7 @@ tor_addr_lookup(const char *name, uint16_t family, tor_addr_t *addr)
     memset(&hints, 0, sizeof(hints));
     hints.ai_family = family;
     hints.ai_socktype = SOCK_STREAM;
-    err = getaddrinfo(name, NULL, &hints, &res);
+    err = sandbox_getaddrinfo(name, &res);
     if (!err) {
       best = NULL;
       for (res_p = res; res_p; res_p = res_p->ai_next) {
diff --git a/src/common/sandbox.c b/src/common/sandbox.c
index 210aa7c..c71efb0 100644
--- a/src/common/sandbox.c
+++ b/src/common/sandbox.c
@@ -55,6 +55,8 @@
 
 static sandbox_cfg_t *filter_dynamic = NULL;
 
+static struct addrinfo *sb_addr_info= NULL;
+
 /** Variable used for storing all syscall numbers that will be allowed with the
  * stage 1 general Tor sandbox.
  */
@@ -262,13 +264,13 @@ sb_open(scmp_filter_ctx ctx, sandbox_cfg_t *filter)
   }
 
   // problem: required by getaddrinfo
-  rc = seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(open), 1,
-        SCMP_CMP(1, SCMP_CMP_EQ, O_RDONLY|O_CLOEXEC));
-  if (rc != 0) {
-    log_err(LD_BUG,"(Sandbox) failed to add open syscall, received libseccomp "
-        "error %d", rc);
-    return rc;
-  }
+//  rc = seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(open), 1,
+//        SCMP_CMP(1, SCMP_CMP_EQ, O_RDONLY|O_CLOEXEC));
+//  if (rc != 0) {
+//    log_err(LD_BUG,"(Sandbox) failed to add open syscall, received libseccomp "
+//        "error %d", rc);
+//    return rc;
+//  }
 
   return 0;
 }
@@ -288,8 +290,8 @@ sb_openat(scmp_filter_ctx ctx, sandbox_cfg_t *filter)
           SCMP_CMP(2, SCMP_CMP_EQ, O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|
               O_CLOEXEC));
       if (rc != 0) {
-        log_err(LD_BUG,"(Sandbox) failed to add openat syscall, received libseccomp "
-            "error %d", rc);
+        log_err(LD_BUG,"(Sandbox) failed to add openat syscall, received "
+            "libseccomp error %d", rc);
         return rc;
       }
     }
@@ -862,6 +864,54 @@ sandbox_cfg_allow_execve_array(sandbox_cfg_t **cfg, int num, ...)
   return 0;
 }
 
+int sandbox_getaddrinfo(const char *name, struct addrinfo **res)
+{
+  char hname[256];
+
+  if (!res) {
+    return -2;
+  }
+  *res = NULL;
+
+  if (gethostname(hname, sizeof(hname)) < 0) {
+    return -1;
+  }
+
+  if (strncmp(name, hname, sizeof(hname)) || sb_addr_info == NULL) {
+    log_err(LD_BUG,"(Sandbox) failed for hname %s!", name);
+    return -1;
+  }
+
+  *res = sb_addr_info;
+  return 0;
+}
+
+static int
+init_addrinfo(void)
+{
+  int ret;
+  struct addrinfo hints;
+  char hname[256];
+
+  sb_addr_info = NULL;
+
+  if (gethostname(hname, sizeof(hname)) < 0) {
+    return -1;
+  }
+
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = AF_INET;
+  hints.ai_socktype = SOCK_STREAM;
+
+  ret = getaddrinfo(hname, NULL, &hints, &sb_addr_info);
+  if(ret) {
+    sb_addr_info = NULL;
+    return -2;
+  }
+
+  return 0;
+}
+
 static int
 add_param_filter(scmp_filter_ctx ctx, sandbox_cfg_t* cfg)
 {
@@ -1047,6 +1097,10 @@ initialise_libseccomp_sandbox(sandbox_cfg_t* cfg)
   if (install_sigsys_debugging())
     return -1;
 
+  if (init_addrinfo()) {
+    return -4;
+  }
+
   if (install_syscall_filter(cfg))
     return -2;
 
diff --git a/src/common/sandbox.h b/src/common/sandbox.h
index ad31e54..6cb827e 100644
--- a/src/common/sandbox.h
+++ b/src/common/sandbox.h
@@ -34,6 +34,7 @@
 #endif
 #include <sys/ucontext.h>
 #include <seccomp.h>
+#include <netdb.h>
 
 /** Security measure for filter string parameter lengths*/
 #define MAX_PARAM_LEN 64
@@ -91,6 +92,9 @@ typedef struct {
 
 #endif // __linux__
 
+/** Replacement for getaddrinfo(), using pre-recorded results. */
+int sandbox_getaddrinfo(const char *name, struct addrinfo **res);
+
 /** Use <b>fd</b> to log non-survivable sandbox violations. */
 void sandbox_set_debugging_fd(int fd);