Messages in this thread | | | Date | Mon, 20 May 2013 17:10:01 +0200 | From | Oleg Nesterov <> | Subject | Re: [RFC PATCH] kmod: add ability to swap root in usermode helper |
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On 05/20, Stanislav Kinsbursky wrote: > > 20.05.2013 17:57, Oleg Nesterov пишет: >> >> Why do we need the new member/arguments? >> >>> @@ -215,6 +216,9 @@ static int ____call_usermodehelper(void *data) >>> */ >>> set_user_nice(current, 0); >>> >>> + if (sub_info->root) >>> + set_fs_root(current->fs, sub_info->root); >> >> Can't subprocess_info->init() do this? You can pass root as ->data. >> >> IOW, unless I missed something, nfs can do this without any changes >> in kmod.c. >> >> Oleg. >> > > Thanks for the comment. > Yes, it definitely can. But, NFS server in the the only place. Usermode helper in > called from NFS client code and thus the same functionality is required there as well.
Not sure I understand... OK, and why NFS client can't use the same functionality?
> Moreover, set_fs_root() is not exported.
Then it should be exported, I think ;)
Or you can export the new helper.
> And adding an ability of a root swap to usermode helper looks quite logical. At least from the > "containers" point of view, which usually have it's own root.
But it is not logical to uglify the code, imho.
OK, why nfs can't simply use this code
static int umh_set_fs_root(struct subprocess_info *info, struct cred *new) { set_fs_root(current->fs, sub_info->data); return 0; }
int call_usermodehelper_root(char *path, char **argv, char **envp, int wait, struct path *root) {
struct subprocess_info *info;
info = call_usermodehelper_setup(path, argv, envp, gfp_mask, umh_set_fs_root, NULL, root); if (info == NULL) return -ENOMEM; return call_usermodehelper_exec(info, wait); }
? Why do you want to add the new member, the new arguments, the new helpers?
Oleg.
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