[CRIU] [PATCHv2] dump: preserve the dumpable flag on criu dump/restore

[Filipe Brandenburger]

Preserve the dumpable flag, which affects whether a core dump will be
generated, but also affects the ownership of the virtual files under
/proc/$pid after restoring a process.

Tested: Restored a process with a criu including this patch and looked
at /proc/$pid to confirm that the virtual files were no longer all owned
by root:root.

zdtm tests pass except for cow01 which seems to be broken.
(see https://bugzilla.openvz.org/show_bug.cgi?id=2967 for details.)

This patch fixes https://bugzilla.openvz.org/show_bug.cgi?id=2968

Signed-off-by: Filipe Brandenburger <filbranden at google.com>
Change-Id: I8c386508448a84368a86666f2d7500b252a78bbf
---
 cr-dump.c          |  3 +++
 include/parasite.h |  2 ++
 include/prctl.h    |  6 ++++++
 pie/parasite.c     |  1 +
 pie/restorer.c     | 21 +++++++++++++++++++++
 protobuf/mm.proto  |  2 ++
 6 files changed, 35 insertions(+)

diff --git a/cr-dump.c b/cr-dump.c
index a4100c1c40f1..9683a4ef5faf 100644
--- a/cr-dump.c
+++ b/cr-dump.c
@@ -455,6 +455,9 @@ static int dump_task_mm(pid_t pid, const struct proc_pid_stat *stat,
 
 	mme.mm_brk = misc->brk;
 
+	mme.dumpable = misc->dumpable;
+	mme.has_dumpable = true;
+
 	mme.n_mm_saved_auxv = AT_VECTOR_SIZE;
 	mme.mm_saved_auxv = xmalloc(pb_repeated_size(&mme, mm_saved_auxv));
 	if (!mme.mm_saved_auxv)
diff --git a/include/parasite.h b/include/parasite.h
index dd14da57c07e..9041ac842276 100644
--- a/include/parasite.h
+++ b/include/parasite.h
@@ -157,6 +157,8 @@ struct parasite_dump_misc {
 
 	struct parasite_dump_thread	ti;
 	u64 cycles;
+
+	int dumpable;
 };
 
 #define PARASITE_MAX_GROUPS	(PAGE_SIZE / sizeof(unsigned int) - 2 * sizeof(unsigned))
diff --git a/include/prctl.h b/include/prctl.h
index 79fcb3529e26..9815c9f3ac3d 100644
--- a/include/prctl.h
+++ b/include/prctl.h
@@ -16,6 +16,12 @@
 #ifndef PR_SET_SECUREBITS
 # define PR_SET_SECUREBITS	28
 #endif
+#ifndef PR_GET_DUMPABLE
+# define PR_GET_DUMPABLE	3
+#endif
+#ifndef PR_SET_DUMPABLE
+# define PR_SET_DUMPABLE	4
+#endif
 
 #ifndef PR_SET_MM
 #define PR_SET_MM		35
diff --git a/pie/parasite.c b/pie/parasite.c
index 5f13191fdad8..0c30603610ec 100644
--- a/pie/parasite.c
+++ b/pie/parasite.c
@@ -163,6 +163,7 @@ static int dump_misc(struct parasite_dump_misc *args)
 	args->umask = sys_umask(0);
 	sys_umask(args->umask); /* never fails */
 	args->cycles = arch_read_cycles();
+	args->dumpable = sys_prctl(PR_GET_DUMPABLE, 0, 0, 0, 0);
 
 	return dump_thread_common(&args->ti);
 }
diff --git a/pie/restorer.c b/pie/restorer.c
index ac8013971029..c8bf073f20f1 100644
--- a/pie/restorer.c
+++ b/pie/restorer.c
@@ -30,6 +30,7 @@
 #include "restorer.h"
 
 #include "protobuf/creds.pb-c.h"
+#include "protobuf/mm.pb-c.h"
 
 #include "asm/restorer.h"
 #include "asm/cycles.h"
@@ -188,6 +189,21 @@ static int restore_creds(CredsEntry *ce)
 	return 0;
 }
 
+static int restore_dumpable_flag(MmEntry *mme)
+{
+	int ret;
+
+	if (mme->has_dumpable) {
+		ret = sys_prctl(PR_SET_DUMPABLE, mme->dumpable, 0, 0, 0);
+		if (ret) {
+			pr_err("Unable to set PR_SET_DUMPABLE: %d\n", ret);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
 static void restore_sched_info(struct rst_sched_param *p)
 {
 	struct sched_param parm;
@@ -296,6 +312,10 @@ long __export_restore_thread(struct thread_restore_args *args)
 	if (ret)
 		goto core_restore_end;
 
+	ret = restore_dumpable_flag(&args->ta->mm);
+	if (ret)
+		goto core_restore_end;
+
 	pr_info("%ld: Restored\n", sys_gettid());
 
 	restore_finish_stage(CR_STATE_RESTORE);
@@ -930,6 +950,7 @@ long __export_restore_task(struct task_restore_args *args)
 	 */
 
 	ret = restore_creds(&args->creds);
+	ret = ret || restore_dumpable_flag(&args->mm);
 
 	futex_set_and_wake(&thread_inprogress, args->nr_threads);
 
diff --git a/protobuf/mm.proto b/protobuf/mm.proto
index b809061afdd1..1556b602d588 100644
--- a/protobuf/mm.proto
+++ b/protobuf/mm.proto
@@ -17,4 +17,6 @@ message mm_entry {
 	repeated uint64	mm_saved_auxv	= 13;
 
 	repeated vma_entry vmas		= 14;
+
+	optional int32	dumpable	= 15;
 }
-- 
1.9.1.423.g4596e3a