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From 88e8824997b26b821530384bb944e15a63e81301 Mon Sep 17 00:00:00 2001
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From: Colin Walters <walters@verbum.org>
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Date: Thu, 22 Aug 2013 13:55:21 -0400
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Subject: [PATCH] polkit: Avoid race condition in scraping /proc
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If a calling process execve()s a setuid program, it can appear to be
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uid 0. Since we're receiving requests over DBus, avoid this by simply
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passing system-bus-name as a subject.
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https://bugzilla.redhat.com/show_bug.cgi?id=1005142
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---
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src/shared/polkit.c | 31 +++++--------------------------
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1 file changed, 5 insertions(+), 26 deletions(-)
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diff --git a/src/shared/polkit.c b/src/shared/polkit.c
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index cea7074..1c5e9e3 100644
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--- a/src/shared/polkit.c
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+++ b/src/shared/polkit.c
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@@ -38,12 +38,8 @@ int verify_polkit(
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#ifdef ENABLE_POLKIT
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DBusMessage *m = NULL, *reply = NULL;
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- const char *unix_process = "unix-process", *pid = "pid", *starttime = "start-time", *cancel_id = "";
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+ const char *system_bus_name = "system-bus-name", *name = "name", *cancel_id = "";
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uint32_t flags = interactive ? 1 : 0;
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- pid_t pid_raw;
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- uint32_t pid_u32;
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- unsigned long long starttime_raw;
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- uint64_t starttime_u64;
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DBusMessageIter iter_msg, iter_struct, iter_array, iter_dict, iter_variant;
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int r;
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dbus_bool_t authorized = FALSE, challenge = FALSE;
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@@ -68,14 +64,6 @@ int verify_polkit(
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#ifdef ENABLE_POLKIT
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- pid_raw = bus_get_unix_process_id(c, sender, error);
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- if (pid_raw == 0)
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- return -EINVAL;
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-
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- r = get_starttime_of_pid(pid_raw, &starttime_raw);
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- if (r < 0)
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- return r;
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-
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m = dbus_message_new_method_call(
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"org.freedesktop.PolicyKit1",
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"/org/freedesktop/PolicyKit1/Authority",
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@@ -86,22 +74,13 @@ int verify_polkit(
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dbus_message_iter_init_append(m, &iter_msg);
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- pid_u32 = (uint32_t) pid_raw;
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- starttime_u64 = (uint64_t) starttime_raw;
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-
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if (!dbus_message_iter_open_container(&iter_msg, DBUS_TYPE_STRUCT, NULL, &iter_struct) ||
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- !dbus_message_iter_append_basic(&iter_struct, DBUS_TYPE_STRING, &unix_process) ||
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+ !dbus_message_iter_append_basic(&iter_struct, DBUS_TYPE_STRING, &system_bus_name) ||
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!dbus_message_iter_open_container(&iter_struct, DBUS_TYPE_ARRAY, "{sv}", &iter_array) ||
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!dbus_message_iter_open_container(&iter_array, DBUS_TYPE_DICT_ENTRY, NULL, &iter_dict) ||
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- !dbus_message_iter_append_basic(&iter_dict, DBUS_TYPE_STRING, &pid) ||
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- !dbus_message_iter_open_container(&iter_dict, DBUS_TYPE_VARIANT, "u", &iter_variant) ||
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- !dbus_message_iter_append_basic(&iter_variant, DBUS_TYPE_UINT32, &pid_u32) ||
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- !dbus_message_iter_close_container(&iter_dict, &iter_variant) ||
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- !dbus_message_iter_close_container(&iter_array, &iter_dict) ||
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- !dbus_message_iter_open_container(&iter_array, DBUS_TYPE_DICT_ENTRY, NULL, &iter_dict) ||
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- !dbus_message_iter_append_basic(&iter_dict, DBUS_TYPE_STRING, &starttime) ||
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- !dbus_message_iter_open_container(&iter_dict, DBUS_TYPE_VARIANT, "t", &iter_variant) ||
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- !dbus_message_iter_append_basic(&iter_variant, DBUS_TYPE_UINT64, &starttime_u64) ||
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+ !dbus_message_iter_append_basic(&iter_dict, DBUS_TYPE_STRING, &name) ||
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+ !dbus_message_iter_open_container(&iter_dict, DBUS_TYPE_VARIANT, "s", &iter_variant) ||
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+ !dbus_message_iter_append_basic(&iter_variant, DBUS_TYPE_STRING, &sender) ||
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!dbus_message_iter_close_container(&iter_dict, &iter_variant) ||
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!dbus_message_iter_close_container(&iter_array, &iter_dict) ||
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!dbus_message_iter_close_container(&iter_struct, &iter_array) ||
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