[tracker] libtracker-common: Whitelist openat()

[Carlos Garnacho <carlosg src gnome org>]

commit 20c715e249f6ea9a36ab09bbcda0c695c3062b79
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue May 9 14:55:26 2017 +0200

    libtracker-common: Whitelist openat()
    
    With the same caveats than open().
    
    https://bugzilla.gnome.org/show_bug.cgi?id=782514

 src/libtracker-common/tracker-seccomp.c |   14 ++++++++++++--
 1 files changed, 12 insertions(+), 2 deletions(-)
---
diff --git a/src/libtracker-common/tracker-seccomp.c b/src/libtracker-common/tracker-seccomp.c
index 1af380c..ec873f5 100644
--- a/src/libtracker-common/tracker-seccomp.c
+++ b/src/libtracker-common/tracker-seccomp.c
@@ -182,8 +182,8 @@ tracker_seccomp_init (void)
                              SCMP_CMP(0, SCMP_CMP_EQ, 2)) < 0)
                goto out;
 
-       /* Special requirements for open, allow O_RDONLY calls, but fail
-        * if write permissions are requested.
+       /* Special requirements for open/openat, allow O_RDONLY calls,
+         * but fail if write permissions are requested.
         */
        if (seccomp_rule_add (ctx, SCMP_ACT_ALLOW, SCMP_SYS(open), 1,
                              SCMP_CMP(1, SCMP_CMP_MASKED_EQ, O_WRONLY | O_RDWR, 0)) < 0)
@@ -195,6 +195,16 @@ tracker_seccomp_init (void)
                              SCMP_CMP(1, SCMP_CMP_MASKED_EQ, O_RDWR, O_RDWR)) < 0)
                goto out;
 
+       if (seccomp_rule_add (ctx, SCMP_ACT_ALLOW, SCMP_SYS(openat), 1,
+                             SCMP_CMP(2, SCMP_CMP_MASKED_EQ, O_WRONLY | O_RDWR, 0)) < 0)
+               goto out;
+       if (seccomp_rule_add (ctx, SCMP_ACT_ERRNO (EACCES), SCMP_SYS(openat), 1,
+                             SCMP_CMP(2, SCMP_CMP_MASKED_EQ, O_WRONLY, O_WRONLY)) < 0)
+               goto out;
+       if (seccomp_rule_add (ctx, SCMP_ACT_ERRNO (EACCES), SCMP_SYS(openat), 1,
+                             SCMP_CMP(2, SCMP_CMP_MASKED_EQ, O_RDWR, O_RDWR)) < 0)
+               goto out;
+
        g_debug ("Loading seccomp rules.");
 
        if (seccomp_load (ctx) >= 0)