The uid is a new addition; this allows callers such as libvirt to
close a race condition in reading the uid of the process talking to
them. They can read it via getsockopt(SO_PEERCRED) or equivalent,
rather than having pkcheck look at /proc later after the fact.
Programs which invoke pkcheck but need to know beforehand (i.e. at
compile time) whether or not it supports passing the uid can
use:
pkcheck_supports_uid=$($PKG_CONFIG --variable pkcheck_supports_uid polkit-gobject-1)
test x$pkcheck_supports_uid = xyes
diff -urN polkit/data/polkit-gobject-1.pc.in polkit-0.107/data/polkit-gobject-1.pc.in
--- polkit/data/polkit-gobject-1.pc.in 2012-04-24 18:05:34.000000000 +0200
+++ polkit-0.107/data/polkit-gobject-1.pc.in 2013-09-18 20:33:16.451783171 +0200
@@ -11,3 +11,6 @@
Libs: -L${libdir} -lpolkit-gobject-1
Cflags: -I${includedir}/polkit-1
Requires: gio-2.0 >= 2.18 glib-2.0 >= 2.18
+# Programs using pkcheck can use this to determine
+# whether or not it can be passed a uid.
+pkcheck_supports_uid=true
diff -urN polkit/docs/man/pkcheck.xml polkit-0.107/docs/man/pkcheck.xml
--- polkit/docs/man/pkcheck.xml 2012-06-04 19:47:39.000000000 +0200
+++ polkit-0.107/docs/man/pkcheck.xml 2013-09-18 20:33:16.451783171 +0200
@@ -55,6 +55,9 @@
pid,pid-start-time
+
+ pid,pid-start-time,uid
+
@@ -90,7 +93,7 @@
DESCRIPTIONpkcheck is used to check whether a process, specified by
- either or ,
+ either (see below) or ,
is authorized for action. The
option can be used zero or more times to pass details about action.
If is passed, pkcheck blocks
@@ -160,15 +163,23 @@
NOTES
- Since process identifiers can be recycled, the caller should always use
- pid,pid-start-time to specify the process
- to check for authorization when using the option.
- The value of pid-start-time
- can be determined by consulting e.g. the
+ Do not use either the bare pid or
+ pid,start-time syntax forms for
+ . There are race conditions in both.
+ New code should always use
+ pid,pid-start-time,uid. The value of
+ start-time can be determined by
+ consulting e.g. the
proc5
- file system depending on the operating system. If only pid
- is passed to the option, then pkcheck
- will look up the start time itself but note that this may be racy.
+ file system depending on the operating system. If fewer than 3
+ arguments are passed, pkcheck will attempt to
+ look up them up internally, but note that this may be racy.
+
+
+ If your program is a daemon with e.g. a custom Unix domain
+ socket, you should determine the uid
+ parameter via operating system mechanisms such as
+ PEERCRED.
diff -urN polkit/src/programs/pkcheck.c polkit-0.107/src/programs/pkcheck.c
--- polkit/src/programs/pkcheck.c 2012-04-24 18:05:34.000000000 +0200
+++ polkit-0.107/src/programs/pkcheck.c 2013-09-18 20:33:16.452783171 +0200
@@ -372,6 +372,7 @@
else if (g_strcmp0 (argv[n], "--process") == 0 || g_strcmp0 (argv[n], "-p") == 0)
{
gint pid;
+ guint uid;
guint64 pid_start_time;
n++;
@@ -381,7 +382,11 @@
goto out;
}
- if (sscanf (argv[n], "%i,%" G_GUINT64_FORMAT, &pid, &pid_start_time) == 2)
+ if (sscanf (argv[n], "%i,%" G_GUINT64_FORMAT ",%u", &pid, &pid_start_time, &uid) == 3)
+ {
+ subject = polkit_unix_process_new_for_owner (pid, pid_start_time, uid);
+ }
+ else if (sscanf (argv[n], "%i,%" G_GUINT64_FORMAT, &pid, &pid_start_time) == 2)
{
subject = polkit_unix_process_new_full (pid, pid_start_time);
}