Commit 5202efe5 authored Jun 25, 2015 by Nicolas Iooss Committed by Linus Torvalds Jun 25, 2015

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>

parent 89bfae43

Documentation/sysctl/kernel.txt

+2 −2

Original line number	Diff line number	Diff line
		@@ -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

fs/coredump.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -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",

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