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Subject[PATCH 23/30] cr: deal with fs_struct
Dump umask, root, pwd.

root, pwd are dumped as names returned by d_path.

FIXME, FIXME, FIXME: think through what to do with overmount
and vfsmount themselves!!!

FIXME: restore root, pwd, tsk->fs itself

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
include/linux/cr.h | 12 +++
kernel/cr/Makefile | 1
kernel/cr/cpt-sys.c | 6 +
kernel/cr/cr-fs.c | 194 ++++++++++++++++++++++++++++++++++++++++++++++++++++
kernel/cr/cr-task.c | 2
kernel/cr/cr.h | 4 +
6 files changed, 219 insertions(+)
--- a/include/linux/cr.h
+++ b/include/linux/cr.h
@@ -41,6 +41,7 @@ struct cr_object_header {
#define CR_OBJ_PID 10
#define CR_OBJ_FILES_STRUCT 11
#define CR_OBJ_FD 12
+#define CR_OBJ_FS_STRUCT 13
__u32 cr_type; /* object type */
__u32 cr_len; /* object length in bytes including header */
} __packed;
@@ -61,6 +62,7 @@ struct cr_image_task_struct {
cr_pos_t cr_pos_real_parent;
cr_pos_t cr_pos_mm;
cr_pos_t cr_pos_pids[3];
+ cr_pos_t cr_pos_fs;
cr_pos_t cr_pos_files;
cr_pos_t cr_pos_nsproxy;

@@ -231,6 +233,16 @@ struct cr_image_vma_content {
/* __u8 cr_data[cr_nr_pages * cr_page_size]; */
} __packed;

+struct cr_image_fs_struct {
+ struct cr_object_header cr_hdr;
+
+ __u32 cr_umask;
+ __u32 cr_root_len;
+ __u32 cr_pwd_len;
+ /* __u8 cr_root[cr_root_len] */
+ /* __u8 cr_pwd[cr_pwd_len] */
+} __packed;
+
struct cr_image_files_struct {
struct cr_object_header cr_hdr;
} __packed;
--- a/kernel/cr/Makefile
+++ b/kernel/cr/Makefile
@@ -2,6 +2,7 @@ obj-$(CONFIG_CR) += cr.o
cr-y := cpt-sys.o rst-sys.o
cr-y += cr-context.o
cr-y += cr-file.o
+cr-y += cr-fs.o
cr-y += cr-mm.o
cr-y += cr-nsproxy.o
cr-y += cr-pid.o
--- a/kernel/cr/cpt-sys.c
+++ b/kernel/cr/cpt-sys.c
@@ -83,6 +83,9 @@ static int cr_collect(struct cr_context *ctx)
rv = cr_collect_all_file(ctx);
if (rv < 0)
return rv;
+ rv = cr_collect_all_fs_struct(ctx);
+ if (rv < 0)
+ return rv;
rv = cr_collect_all_pid(ctx);
if (rv < 0)
return rv;
@@ -131,6 +134,9 @@ static int cr_dump(struct cr_context *ctx)
rv = cr_dump_all_files_struct(ctx);
if (rv < 0)
return rv;
+ rv = cr_dump_all_fs_struct(ctx);
+ if (rv < 0)
+ return rv;
rv = cr_dump_all_uts_ns(ctx);
if (rv < 0)
return rv;
new file mode 100644
--- /dev/null
+++ b/kernel/cr/cr-fs.c
@@ -0,0 +1,194 @@
+/* Copyright (C) 2000-2009 Parallels Holdings, Ltd. */
+#include <linux/dcache.h>
+#include <linux/fs.h>
+#include <linux/fs_struct.h>
+#include <linux/sched.h>
+
+#include <linux/cr.h>
+#include "cr.h"
+
+static int cr_collect_fs_struct(struct cr_context *ctx, struct fs_struct *fs)
+{
+ int rv;
+
+ rv = cr_collect_object(ctx, fs, CR_CTX_FS_STRUCT);
+ printk("collect fs_struct %p: rv %d\n", fs, rv);
+ return rv;
+}
+
+int cr_collect_all_fs_struct(struct cr_context *ctx)
+{
+ struct cr_object *obj;
+ int rv;
+
+ for_each_cr_object(ctx, obj, CR_CTX_TASK_STRUCT) {
+ struct task_struct *tsk = obj->o_obj;
+
+ rv = cr_collect_fs_struct(ctx, tsk->fs);
+ if (rv < 0)
+ return rv;
+ }
+ for_each_cr_object(ctx, obj, CR_CTX_FS_STRUCT) {
+ struct fs_struct *fs = obj->o_obj;
+ unsigned int cnt = fs->users;
+
+ if (obj->o_count != cnt) {
+ printk("%s: fs_struct %p has external references %lu:%u\n", __func__, fs, obj->o_count, cnt);
+ return -EINVAL;
+ }
+ }
+ return 0;
+}
+
+static int cr_dump_fs_struct(struct cr_context *ctx, struct cr_object *obj)
+{
+ struct fs_struct *fs = obj->o_obj;
+ struct cr_image_fs_struct *i;
+ char *buf_root, *name_root, *buf_pwd, *name_pwd;
+ int rv;
+
+ i = cr_prepare_image(CR_OBJ_FS_STRUCT, sizeof(*i));
+ if (!i)
+ return -ENOMEM;
+
+ i->cr_umask = fs->umask;
+
+ buf_root = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!buf_root) {
+ kfree(i);
+ return -ENOMEM;
+ }
+ name_root = d_path(&fs->root, buf_root, PAGE_SIZE);
+ if (IS_ERR(name_root)) {
+ kfree(buf_root);
+ kfree(i);
+ return PTR_ERR(name_root);
+ }
+ i->cr_root_len = buf_root + PAGE_SIZE - 1 - name_root;
+ i->cr_hdr.cr_len += i->cr_root_len;
+
+ buf_pwd = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!buf_pwd) {
+ kfree(buf_root);
+ kfree(i);
+ return -ENOMEM;
+ }
+ name_pwd = d_path(&fs->pwd, buf_pwd, PAGE_SIZE);
+ if (IS_ERR(name_pwd)) {
+ kfree(buf_pwd);
+ kfree(buf_root);
+ kfree(i);
+ return PTR_ERR(name_pwd);
+ }
+ i->cr_pwd_len = buf_pwd + PAGE_SIZE - 1 - name_pwd;
+ i->cr_hdr.cr_len += i->cr_pwd_len;
+
+ obj->o_pos = ctx->cr_dump_file->f_pos;
+ rv = cr_write(ctx, i, sizeof(*i));
+ if (rv < 0) {
+ kfree(buf_pwd);
+ kfree(buf_root);
+ kfree(i);
+ return rv;
+ }
+ rv = cr_write(ctx, name_root, i->cr_root_len);
+ if (rv < 0) {
+ kfree(buf_pwd);
+ kfree(buf_root);
+ kfree(i);
+ return rv;
+ }
+ rv = cr_write(ctx, name_pwd, i->cr_pwd_len);
+ if (rv < 0) {
+ kfree(buf_pwd);
+ kfree(buf_root);
+ kfree(i);
+ return rv;
+ }
+ printk("dump fs_struct %p: umask %03o, root '%.*s', pwd '%.*s'\n", fs, fs->umask, i->cr_root_len, name_root, i->cr_pwd_len, name_pwd);
+
+ kfree(buf_pwd);
+ kfree(buf_root);
+ kfree(i);
+ return 0;
+}
+
+int cr_dump_all_fs_struct(struct cr_context *ctx)
+{
+ struct cr_object *obj;
+ int rv;
+
+ for_each_cr_object(ctx, obj, CR_CTX_FS_STRUCT) {
+ rv = cr_dump_fs_struct(ctx, obj);
+ if (rv < 0)
+ return rv;
+ }
+ return 0;
+}
+
+int cr_restore_fs_struct(struct cr_context *ctx, loff_t pos)
+{
+ struct cr_image_fs_struct *i, *tmp;
+ struct fs_struct *fs;
+ struct cr_object *obj;
+ char *cr_root, *cr_pwd;
+ int rv;
+
+ i = kzalloc(sizeof(*i), GFP_KERNEL);
+ if (!i)
+ return -ENOMEM;
+ rv = cr_pread(ctx, i, sizeof(*i), pos);
+ if (rv < 0) {
+ kfree(i);
+ return rv;
+ }
+ if (i->cr_hdr.cr_type != CR_OBJ_FS_STRUCT) {
+ kfree(i);
+ return -EINVAL;
+ }
+ tmp = i;
+ i = krealloc(i, sizeof(*i) + i->cr_root_len + i->cr_pwd_len + 2, GFP_KERNEL);
+ if (!i) {
+ kfree(tmp);
+ return -ENOMEM;
+ }
+
+ cr_root = (char *)(i + 1);
+ rv = cr_pread(ctx, cr_root, i->cr_root_len, pos + sizeof(*i));
+ if (rv < 0) {
+ kfree(i);
+ return rv;
+ }
+ cr_root[i->cr_root_len] = '\0';
+
+ cr_pwd = cr_root + i->cr_root_len + 1;
+ rv = cr_pread(ctx, cr_pwd, i->cr_pwd_len, pos + sizeof(*i) + i->cr_root_len);
+ if (rv < 0) {
+ kfree(i);
+ return rv;
+ }
+ cr_pwd[i->cr_pwd_len] = '\0';
+
+ fs = kmem_cache_zalloc(fs_cachep, GFP_KERNEL);
+ if (!fs) {
+ kfree(i);
+ return -ENOMEM;
+ }
+ fs->users = 1;
+ fs->in_exec = 0;
+ rwlock_init(&fs->lock);
+
+ fs->umask = i->cr_umask;
+
+ obj = cr_object_create(fs);
+ if (!obj) {
+ kmem_cache_free(fs_cachep, fs);
+ kfree(i);
+ return -ENOMEM;
+ }
+ obj->o_pos = pos;
+ list_add(&obj->o_list, &ctx->cr_obj[CR_CTX_FS_STRUCT]);
+ printk("restore fs_struct %p, pos = %lld: umask %03o, root '%s', pwd '%s'\n", fs, (long long)pos, fs->umask, cr_root, cr_pwd);
+ kfree(i);
+ return 0;
+}
--- a/kernel/cr/cr-task.c
+++ b/kernel/cr/cr-task.c
@@ -127,6 +127,8 @@ static int cr_dump_task_struct(struct cr_context *ctx, struct cr_object *obj)
i->cr_pos_pids[2] = tmp->o_pos;
else
i->cr_pos_pids[2] = CR_POS_UNDEF;
+ tmp = cr_find_obj_by_ptr(ctx, tsk->fs, CR_CTX_FS_STRUCT);
+ i->cr_pos_fs = tmp->o_pos;
tmp = cr_find_obj_by_ptr(ctx, tsk->files, CR_CTX_FILES_STRUCT);
i->cr_pos_files = tmp->o_pos;

--- a/kernel/cr/cr.h
+++ b/kernel/cr/cr.h
@@ -24,6 +24,7 @@ struct cr_object {
enum cr_context_obj_type {
CR_CTX_FILE,
CR_CTX_FILES_STRUCT,
+ CR_CTX_FS_STRUCT,
CR_CTX_MM_STRUCT,
CR_CTX_NSPROXY,
CR_CTX_PID,
@@ -73,6 +74,7 @@ static inline void __user *cr_restore_ptr(__u64 ptr)

int cr_collect_all_files_struct(struct cr_context *ctx);
int cr_collect_all_file(struct cr_context *ctx);
+int cr_collect_all_fs_struct(struct cr_context *ctx);
int cr_collect_all_mm_struct(struct cr_context *ctx);
int cr_collect_all_nsproxy(struct cr_context *ctx);
int cr_collect_all_pid_ns(struct cr_context *ctx);
@@ -82,6 +84,7 @@ int cr_collect_all_uts_ns(struct cr_context *ctx);

int cr_dump_all_files_struct(struct cr_context *ctx);
int cr_dump_all_file(struct cr_context *ctx);
+int cr_dump_all_fs_struct(struct cr_context *ctx);
int cr_dump_all_mm_struct(struct cr_context *ctx);
int cr_dump_all_nsproxy(struct cr_context *ctx);
int cr_dump_all_pid_ns(struct cr_context *ctx);
@@ -91,6 +94,7 @@ int cr_dump_all_uts_ns(struct cr_context *ctx);

int cr_restore_files_struct(struct cr_context *ctx, loff_t pos);
int cr_restore_file(struct cr_context *ctx, loff_t pos);
+int cr_restore_fs_struct(struct cr_context *ctx, loff_t pos);
int cr_restore_mm_struct(struct cr_context *ctx, loff_t pos);
int cr_restore_nsproxy(struct cr_context *ctx, loff_t pos);
int cr_restore_pid_ns(struct cr_context *ctx, loff_t pos);

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