From 6072f8b24153d844a3033108a17bcd0c1a967816 Mon Sep 17 00:00:00 2001
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From: Laurent Bigonville <bigon@bigon.be>
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Date: Sat, 3 Mar 2018 11:15:23 +0100
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Subject: [PATCH] Stop using selinux_set_mapping() function
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Currently, if the "dbus" security class or the associated AV doesn't
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exist, dbus-daemon fails to initialize and exits immediately. Also the
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security classes or access vector cannot be reordered in the policy.
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This can be a problem for people developing their own policy or trying
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to access a machine where, for some reasons, there is not policy defined
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at all.
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The code here copy the behaviour of the selinux_check_access() function.
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We cannot use this function here as it doesn't allow us to define the
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AVC entry reference.
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See the discussion at https://marc.info/?l=selinux&m=152163374332372&w=2
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Resolves: https://gitlab.freedesktop.org/dbus/dbus/issues/198
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---
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bus/selinux.c | 75 ++++++++++++++++++++++++++++-----------------------
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1 file changed, 42 insertions(+), 33 deletions(-)
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Upstream-Status: Backport
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Signed-off-by: Nisha.Parrakat <Nisha.Parrakat@kpit.com>
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diff --git a/bus/selinux.c b/bus/selinux.c
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--- a/bus/selinux.c 2021-08-11 14:45:59.048513026 +0000
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+++ b/bus/selinux.c 2021-08-11 14:57:47.144846966 +0000
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@@ -311,24 +311,6 @@
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#endif
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}
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-/*
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- * Private Flask definitions; the order of these constants must
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- * exactly match that of the structure array below!
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- */
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-/* security dbus class constants */
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-#define SECCLASS_DBUS 1
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-
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-/* dbus's per access vector constants */
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-#define DBUS__ACQUIRE_SVC 1
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-#define DBUS__SEND_MSG 2
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-
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-#ifdef HAVE_SELINUX
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-static struct security_class_mapping dbus_map[] = {
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- { "dbus", { "acquire_svc", "send_msg", NULL } },
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- { NULL }
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-};
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-#endif /* HAVE_SELINUX */
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-
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/**
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* Establish dynamic object class and permission mapping and
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* initialize the user space access vector cache (AVC) for D-Bus and set up
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@@ -350,13 +332,6 @@
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_dbus_verbose ("SELinux is enabled in this kernel.\n");
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- if (selinux_set_mapping (dbus_map) < 0)
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- {
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- _dbus_warn ("Failed to set up security class mapping (selinux_set_mapping():%s).",
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- strerror (errno));
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- return FALSE;
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- }
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-
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avc_entry_ref_init (&aeref);
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if (avc_init ("avc", &mem_cb, &log_cb, &thread_cb, &lock_cb) < 0)
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{
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@@ -421,19 +396,53 @@
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static dbus_bool_t
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bus_selinux_check (BusSELinuxID *sender_sid,
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BusSELinuxID *override_sid,
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- security_class_t target_class,
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- access_vector_t requested,
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+ const char *target_class,
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+ const char *requested,
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DBusString *auxdata)
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{
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+ int saved_errno;
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+ security_class_t security_class;
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+ access_vector_t requested_access;
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+
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if (!selinux_enabled)
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return TRUE;
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+ security_class = string_to_security_class (target_class);
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+ if (security_class == 0)
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+ {
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+ saved_errno = errno;
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+ log_callback (SELINUX_ERROR, "Unknown class %s", target_class);
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+ if (security_deny_unknown () == 0)
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+ {
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+ return TRUE;
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+ }
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+
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+ _dbus_verbose ("Unknown class %s\n", target_class);
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+ errno = saved_errno;
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+ return FALSE;
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+ }
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+
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+ requested_access = string_to_av_perm (security_class, requested);
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+ if (requested_access == 0)
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+ {
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+ saved_errno = errno;
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+ log_callback (SELINUX_ERROR, "Unknown permission %s for class %s", requested, target_class);
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+ if (security_deny_unknown () == 0)
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+ {
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+ return TRUE;
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+ }
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+
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+ _dbus_verbose ("Unknown permission %s for class %s\n", requested, target_class);
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+ errno = saved_errno;
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+ return FALSE;
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+ }
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+
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/* Make the security check. AVC checks enforcing mode here as well. */
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if (avc_has_perm (SELINUX_SID_FROM_BUS (sender_sid),
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override_sid ?
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SELINUX_SID_FROM_BUS (override_sid) :
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bus_sid,
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- target_class, requested, &aeref, auxdata) < 0)
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+ security_class, requested_access, &aeref, auxdata) < 0)
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{
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switch (errno)
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{
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@@ -500,8 +509,8 @@
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ret = bus_selinux_check (connection_sid,
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service_sid,
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- SECCLASS_DBUS,
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- DBUS__ACQUIRE_SVC,
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+ "dbus",
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+ "acquire_svc",
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&auxdata);
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_dbus_string_free (&auxdata);
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@@ -629,8 +638,8 @@
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ret = bus_selinux_check (sender_sid,
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recipient_sid,
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- SECCLASS_DBUS,
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- DBUS__SEND_MSG,
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+ "dbus",
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+ "send_msg",
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&auxdata);
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_dbus_string_free (&auxdata);
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