Commit 1d151c33 authored by Cyrill Gorcunov's avatar Cyrill Gorcunov Committed by Linus Torvalds
Browse files

c/r: fcntl: add F_GETOWNER_UIDS option 



When we restore file descriptors we would like them to look exactly as
they were at dumping time.

With help of fcntl it's almost possible, the missing snippet is file
owners UIDs.

To be able to read their values the F_GETOWNER_UIDS is introduced.

This option is valid iif CONFIG_CHECKPOINT_RESTORE is turned on, otherwise
returning -EINVAL.

Signed-off-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
Acked-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 65fed8f6

fs/fcntl.c

+29 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/signal.h>

#include <linux/rcupdate.h>

#include <linux/pid_namespace.h>

#include <linux/user_namespace.h>



#include <asm/poll.h>

#include <asm/siginfo.h>
@@ -340,6 +341,31 @@ static int f_getown_ex(struct file *filp, unsigned long arg) 
	return ret;

}



#ifdef CONFIG_CHECKPOINT_RESTORE

static int f_getowner_uids(struct file *filp, unsigned long arg)

{

	struct user_namespace *user_ns = current_user_ns();

	uid_t * __user dst = (void * __user)arg;

	uid_t src[2];

	int err;



	read_lock(&filp->f_owner.lock);

	src[0] = from_kuid(user_ns, filp->f_owner.uid);

	src[1] = from_kuid(user_ns, filp->f_owner.euid);

	read_unlock(&filp->f_owner.lock);



	err  = put_user(src[0], &dst[0]);

	err |= put_user(src[1], &dst[1]);



	return err;

}

#else

static int f_getowner_uids(struct file *filp, unsigned long arg)

{

	return -EINVAL;

}

#endif



static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,

		struct file *filp)

{
@@ -396,6 +422,9 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, 
	case F_SETOWN_EX:

		err = f_setown_ex(filp, arg);

		break;

	case F_GETOWNER_UIDS:

		err = f_getowner_uids(filp, arg);

		break;

	case F_GETSIG:

		err = filp->f_owner.signum;

		break;

include/asm-generic/fcntl.h

+4 −0
Original line number Diff line number Diff line
@@ -120,6 +120,10 @@ 
#define F_GETOWN_EX	16

#endif



#ifndef F_GETOWNER_UIDS

#define F_GETOWNER_UIDS	17

#endif



#define F_OWNER_TID	0

#define F_OWNER_PID	1

#define F_OWNER_PGRP	2

security/selinux/hooks.c

+1 −0
Original line number Diff line number Diff line
@@ -3180,6 +3180,7 @@ static int selinux_file_fcntl(struct file *file, unsigned int cmd, 
	case F_GETFL:

	case F_GETOWN:

	case F_GETSIG:

	case F_GETOWNER_UIDS:

		/* Just check FD__USE permission */

		err = file_has_perm(cred, file, 0);

		break;

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