b1480cde74
Resolves: #1009538, CVE-2013-4288
101 lines
4.7 KiB
Diff
101 lines
4.7 KiB
Diff
The uid is a new addition; this allows callers such as libvirt to
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close a race condition in reading the uid of the process talking to
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them. They can read it via getsockopt(SO_PEERCRED) or equivalent,
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rather than having pkcheck look at /proc later after the fact.
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Programs which invoke pkcheck but need to know beforehand (i.e. at
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compile time) whether or not it supports passing the uid can
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use:
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pkcheck_supports_uid=$($PKG_CONFIG --variable pkcheck_supports_uid polkit-gobject-1)
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test x$pkcheck_supports_uid = xyes
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diff -urN polkit/data/polkit-gobject-1.pc.in polkit-0.107/data/polkit-gobject-1.pc.in
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--- polkit/data/polkit-gobject-1.pc.in 2012-04-24 18:05:34.000000000 +0200
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+++ polkit-0.107/data/polkit-gobject-1.pc.in 2013-09-18 20:33:16.451783171 +0200
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@@ -11,3 +11,6 @@
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Libs: -L${libdir} -lpolkit-gobject-1
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Cflags: -I${includedir}/polkit-1
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Requires: gio-2.0 >= 2.18 glib-2.0 >= 2.18
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+# Programs using pkcheck can use this to determine
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+# whether or not it can be passed a uid.
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+pkcheck_supports_uid=true
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diff -urN polkit/docs/man/pkcheck.xml polkit-0.107/docs/man/pkcheck.xml
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--- polkit/docs/man/pkcheck.xml 2012-06-04 19:47:39.000000000 +0200
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+++ polkit-0.107/docs/man/pkcheck.xml 2013-09-18 20:33:16.451783171 +0200
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@@ -55,6 +55,9 @@
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<arg choice="plain">
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<replaceable>pid,pid-start-time</replaceable>
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</arg>
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+ <arg choice="plain">
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+ <replaceable>pid,pid-start-time,uid</replaceable>
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+ </arg>
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</group>
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</arg>
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<arg choice="plain">
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@@ -90,7 +93,7 @@
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<title>DESCRIPTION</title>
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<para>
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<command>pkcheck</command> is used to check whether a process, specified by
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- either <option>--process</option> or <option>--system-bus-name</option>,
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+ either <option>--process</option> (see below) or <option>--system-bus-name</option>,
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is authorized for <replaceable>action</replaceable>. The <option>--detail</option>
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option can be used zero or more times to pass details about <replaceable>action</replaceable>.
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If <option>--allow-user-interaction</option> is passed, <command>pkcheck</command> blocks
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@@ -160,15 +163,23 @@
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<refsect1 id="pkcheck-notes">
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<title>NOTES</title>
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<para>
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- Since process identifiers can be recycled, the caller should always use
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- <replaceable>pid,pid-start-time</replaceable> to specify the process
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- to check for authorization when using the <option>--process</option> option.
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- The value of <replaceable>pid-start-time</replaceable>
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- can be determined by consulting e.g. the
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+ Do not use either the bare <replaceable>pid</replaceable> or
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+ <replaceable>pid,start-time</replaceable> syntax forms for
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+ <option>--process</option>. There are race conditions in both.
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+ New code should always use
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+ <replaceable>pid,pid-start-time,uid</replaceable>. The value of
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+ <replaceable>start-time</replaceable> can be determined by
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+ consulting e.g. the
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<citerefentry><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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- file system depending on the operating system. If only <replaceable>pid</replaceable>
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- is passed to the <option>--process</option> option, then <command>pkcheck</command>
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- will look up the start time itself but note that this may be racy.
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+ file system depending on the operating system. If fewer than 3
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+ arguments are passed, <command>pkcheck</command> will attempt to
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+ look up them up internally, but note that this may be racy.
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+ </para>
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+ <para>
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+ If your program is a daemon with e.g. a custom Unix domain
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+ socket, you should determine the <replaceable>uid</replaceable>
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+ parameter via operating system mechanisms such as
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+ <literal>PEERCRED</literal>.
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</para>
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</refsect1>
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diff -urN polkit/src/programs/pkcheck.c polkit-0.107/src/programs/pkcheck.c
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--- polkit/src/programs/pkcheck.c 2012-04-24 18:05:34.000000000 +0200
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+++ polkit-0.107/src/programs/pkcheck.c 2013-09-18 20:33:16.452783171 +0200
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@@ -372,6 +372,7 @@
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else if (g_strcmp0 (argv[n], "--process") == 0 || g_strcmp0 (argv[n], "-p") == 0)
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{
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gint pid;
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+ guint uid;
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guint64 pid_start_time;
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n++;
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@@ -381,7 +382,11 @@
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goto out;
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}
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- if (sscanf (argv[n], "%i,%" G_GUINT64_FORMAT, &pid, &pid_start_time) == 2)
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+ if (sscanf (argv[n], "%i,%" G_GUINT64_FORMAT ",%u", &pid, &pid_start_time, &uid) == 3)
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+ {
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+ subject = polkit_unix_process_new_for_owner (pid, pid_start_time, uid);
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+ }
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+ else if (sscanf (argv[n], "%i,%" G_GUINT64_FORMAT, &pid, &pid_start_time) == 2)
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{
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subject = polkit_unix_process_new_full (pid, pid_start_time);
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}
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