From: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Date: Thu, 25 Jun 2015 22:03:51 +0000 (-0700)
Subject: coredump: use from_kuid/kgid when formatting corename
X-Git-Tag: v4.14-rc1~5177^2~2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=5202efe544c279be152f44f2821010ff7b2d7e5b;p=platform%2Fkernel%2Flinux-rpi.git

coredump: use from_kuid/kgid when formatting corename

When adding __printf attribute to cn_printf, gcc reports some issues:

  fs/coredump.c:213:5: warning: format '%d' expects argument of type
  'int', but argument 3 has type 'kuid_t' [-Wformat=]
       err = cn_printf(cn, "%d", cred->uid);
       ^
  fs/coredump.c:217:5: warning: format '%d' expects argument of type
  'int', but argument 3 has type 'kgid_t' [-Wformat=]
       err = cn_printf(cn, "%d", cred->gid);
       ^

These warnings come from the fact that the value of uid/gid needs to be
extracted from the kuid_t/kgid_t structure before being used as an
integer.  More precisely, cred->uid and cred->gid need to be converted to
either user-namespace uid/gid or to init_user_ns uid/gid.

Use init_user_ns in order not to break existing ABI, and document this in
Documentation/sysctl/kernel.txt.

While at it, format uid and gid values with %u instead of %d because
uid_t/__kernel_uid32_t and gid_t/__kernel_gid32_t are unsigned int.

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index e5d528e..6fccb69 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -197,8 +197,8 @@ core_pattern is used to specify a core dumpfile pattern name.
 	%P	global pid (init PID namespace)
 	%i	tid
 	%I	global tid (init PID namespace)
-	%u	uid
-	%g	gid
+	%u	uid (in initial user namespace)
+	%g	gid (in initial user namespace)
 	%d	dump mode, matches PR_SET_DUMPABLE and
 		/proc/sys/fs/suid_dumpable
 	%s	signal number
diff --git a/fs/coredump.c b/fs/coredump.c
index bbbe139..833a57b 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -209,11 +209,15 @@ static int format_corename(struct core_name *cn, struct coredump_params *cprm)
 				break;
 			/* uid */
 			case 'u':
-				err = cn_printf(cn, "%d", cred->uid);
+				err = cn_printf(cn, "%u",
+						from_kuid(&init_user_ns,
+							  cred->uid));
 				break;
 			/* gid */
 			case 'g':
-				err = cn_printf(cn, "%d", cred->gid);
+				err = cn_printf(cn, "%u",
+						from_kgid(&init_user_ns,
+							  cred->gid));
 				break;
 			case 'd':
 				err = cn_printf(cn, "%d",