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Commit 12a2b4b2 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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coredump: add support for %d=__get_dumpable() in core name 

Some coredump handlers want to create a core file in a way compatible with
standard behavior.  Standard behavior with fs.suid_dumpable = 2 is to
create core file with uid=gid=0.  However, there was no way for coredump
handler to know that the process being dumped was suid'ed.

This patch adds the new %d specifier for format_corename() which simply
reports __get_dumpable(mm->flags), this is compatible with
/proc/sys/fs/suid_dumpable we already have.

Addresses https://bugzilla.redhat.com/show_bug.cgi?id=787135



Developed during a discussion with Denys Vlasenko.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Alex Kelly <alex.page.kelly@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Cong Wang <amwang@redhat.com>
Cc: Jiri Moskovcak <jmoskovc@redhat.com>
Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 179899fd

Documentation/sysctl/kernel.txt

+2 −0
Original line number Diff line number Diff line
@@ -181,6 +181,8 @@ core_pattern is used to specify a core dumpfile pattern name. 
	%p	pid

	%u	uid

	%g	gid

	%d	dump mode, matches PR_SET_DUMPABLE and

		/proc/sys/fs/suid_dumpable

	%s	signal number

	%t	UNIX time of dump

	%h	hostname

fs/coredump.c

+7 −3
Original line number Diff line number Diff line
@@ -149,7 +149,7 @@ static int cn_print_exe_file(struct core_name *cn) 
 * name into corename, which must have space for at least

 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.

 */

static int format_corename(struct core_name *cn, long signr)

static int format_corename(struct core_name *cn, struct coredump_params *cprm)

{

	const struct cred *cred = current_cred();

	const char *pat_ptr = core_pattern;
@@ -194,9 +194,13 @@ static int format_corename(struct core_name *cn, long signr) 
			case 'g':

				err = cn_printf(cn, "%d", cred->gid);

				break;

			case 'd':

				err = cn_printf(cn, "%d",

					__get_dumpable(cprm->mm_flags));

				break;

			/* signal that caused the coredump */

			case 's':

				err = cn_printf(cn, "%ld", signr);

				err = cn_printf(cn, "%ld", cprm->signr);

				break;

			/* UNIX time of coredump */

			case 't': {
@@ -515,7 +519,7 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs) 
	 */

	clear_thread_flag(TIF_SIGPENDING);



	ispipe = format_corename(&cn, signr);

	ispipe = format_corename(&cn, &cprm);



 	if (ispipe) {

		int dump_count;