This patch adds a spot in the task record to save the personality value
of the task_struct.
It also masks out READ_IMPLIES_EXEC before starting to avoid read-only
maps being restored as read-exec. To avoid re-setting this flag too early,
it also introduces a "task_ctx" object to hold information that may be
collected when reading the task structure, but needs to be restored at a
later time (such as after the maps are read). Since there may be additional
settings that need to be deferred until the end of task restore, I decided
to add the context object and a "cleanup" function to wrap things up.
Changes in v2:
- Change __u64 to __u32 in the cr_task_hdr
Signed-off-by: Dan Smith <danms@xxxxxxxxxx>
---
checkpoint/ckpt_task.c | 2 ++
checkpoint/restart.c | 8 ++++++++
checkpoint/rstr_task.c | 25 +++++++++++++++++++++++--
include/linux/checkpoint_hdr.h | 2 ++
4 files changed, 35 insertions(+), 2 deletions(-)
diff --git a/checkpoint/ckpt_task.c b/checkpoint/ckpt_task.c
index 4d19e31..6a4118a 100644
--- a/checkpoint/ckpt_task.c
+++ b/checkpoint/ckpt_task.c
@@ -38,6 +38,8 @@ static int cr_write_task_struct(struct cr_ctx *ctx, struct task_struct *t)
hh->exit_code = t->exit_code;
hh->exit_signal = t->exit_signal;
+ hh->personality = current->personality;
+
hh->task_comm_len = TASK_COMM_LEN;
/* FIXME: save remaining relevant task_struct fields */
diff --git a/checkpoint/restart.c b/checkpoint/restart.c
index c6bcfac..2ad4b30 100644
--- a/checkpoint/restart.c
+++ b/checkpoint/restart.c
@@ -15,6 +15,7 @@
#include <linux/magic.h>
#include <linux/checkpoint.h>
#include <linux/checkpoint_hdr.h>
+#include <linux/personality.h>
#include <asm/syscall.h>
#include "checkpoint_arch.h"
@@ -524,6 +525,13 @@ int do_restart(struct cr_ctx *ctx, pid_t pid)
{
int ret;
+ /* Remove the READ_IMPLIES_EXEC flag from our personality
+ * (if present) so that our restart logic doesn't change read
+ * maps to read-execute. If the task had this flag set at
+ * checkpoint, it will be restored later.
+ */
+ current->personality &= ~READ_IMPLIES_EXEC;
+
if (ctx)
ret = do_restart_root(ctx, pid);
else
diff --git a/checkpoint/rstr_task.c b/checkpoint/rstr_task.c
index fe5c059..bb09f99 100644
--- a/checkpoint/rstr_task.c
+++ b/checkpoint/rstr_task.c
@@ -20,8 +20,13 @@
#include "checkpoint_arch.h"
+/* Per-task settings that need to be restored at the end of task restart */
+struct cr_task_ctx {
+ unsigned int personality;
+};
+
/* read the task_struct into the current task */
-static int cr_read_task_struct(struct cr_ctx *ctx)
+static int cr_read_task_struct(struct cr_ctx *ctx, struct cr_task_ctx *tsk_ctx)
{
struct cr_hdr_task *hh;
struct task_struct *t = current;
@@ -52,6 +57,8 @@ static int cr_read_task_struct(struct cr_ctx *ctx)
}
kfree(buf);
+ tsk_ctx->personality = hh->personality;
+
/* FIXME: restore remaining relevant task_struct fields */
out:
cr_hbuf_put(ctx, sizeof(*hh));
@@ -314,12 +321,22 @@ static int cr_read_namespaces(struct cr_ctx *ctx)
return ret;
}
+int cr_task_cleanup(struct cr_ctx *ctx, struct cr_task_ctx *tsk_ctx)
+{
+ current->personality = tsk_ctx->personality;
+
+ return 0;
+}
+
/* read the entire state of the current task */
int cr_read_task(struct cr_ctx *ctx)
{
int ret;
+ struct cr_task_ctx tsk_ctx;
+
+ memset(&tsk_ctx, 0, sizeof(tsk_ctx));
- ret = cr_read_task_struct(ctx);
+ ret = cr_read_task_struct(ctx, &tsk_ctx);
cr_debug("ret %d\n", ret);
if (ret < 0)
goto out;
@@ -341,6 +358,10 @@ int cr_read_task(struct cr_ctx *ctx)
goto out;
ret = cr_read_cpu(ctx);
cr_debug("cpu: ret %d\n", ret);
+ if (ret < 0)
+ goto out;
+ ret = cr_task_cleanup(ctx, &tsk_ctx);
+ cr_debug("cleanup: ret %d\n", ret);
out:
return ret;
}
diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
index 92b0336..a3f0b7e 100644
--- a/include/linux/checkpoint_hdr.h
+++ b/include/linux/checkpoint_hdr.h
@@ -127,6 +127,8 @@ struct cr_hdr_task {
__u32 exit_code;
__u32 exit_signal;
+ __u32 personality;
+
__u32 task_comm_len;
} __attribute__((aligned(8)));
--
1.6.1
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