[PATCH] fcntl: Add F_GETOWNER_UIDS option v3

[PATCH] fcntl: Add F_GETOWNER_UIDS option v3

[Cyrill Gorcunov]

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.

v3:
 - rebased on Eric's kuids

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
CC: "Eric W. Biederman" <ebiederm@xmission.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: "Serge E. Hallyn" <serge@hallyn.com>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Pavel Emelyanov <xemul@parallels.com>
---
 fs/fcntl.c                  |   29 +++++++++++++++++++++++++++++
 include/asm-generic/fcntl.h |    4 ++++
 security/selinux/hooks.c    |    1 +
 3 files changed, 34 insertions(+)

Index: linux-2.6.git/fs/fcntl.c
===================================================================
--- linux-2.6.git.orig/fs/fcntl.c
+++ linux-2.6.git/fs/fcntl.c
@@ -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
 	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 in
 	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;
Index: linux-2.6.git/include/asm-generic/fcntl.h
===================================================================
--- linux-2.6.git.orig/include/asm-generic/fcntl.h
+++ linux-2.6.git/include/asm-generic/fcntl.h
@@ -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
Index: linux-2.6.git/security/selinux/hooks.c
===================================================================
--- linux-2.6.git.orig/security/selinux/hooks.c
+++ linux-2.6.git/security/selinux/hooks.c
@@ -3181,6 +3181,7 @@ static int selinux_file_fcntl(struct fil
 	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;

Re: [PATCH] fcntl: Add F_GETOWNER_UIDS option v3

[Eric W. Biederman]

Cyrill Gorcunov <gorcunov@openvz.org> writes:

> 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.

You want to use from_kuid_munged instead of from_kuid as you are going
directly to userspace, and to userspace for an unmapped uid we want
to say 65534 aka nobody instead of -1.

> v3:
>  - rebased on Eric's kuids

To be clear this is based on my patchset that has been merged into
v3.5-rc1.

Eric


> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
> CC: "Eric W. Biederman" <ebiederm@xmission.com>
> CC: Andrew Morton <akpm@linux-foundation.org>
> CC: "Serge E. Hallyn" <serge@hallyn.com>
> CC: Oleg Nesterov <oleg@redhat.com>
> CC: Pavel Emelyanov <xemul@parallels.com>
> ---
>  fs/fcntl.c                  |   29 +++++++++++++++++++++++++++++
>  include/asm-generic/fcntl.h |    4 ++++
>  security/selinux/hooks.c    |    1 +
>  3 files changed, 34 insertions(+)
>
> Index: linux-2.6.git/fs/fcntl.c
> ===================================================================
> --- linux-2.6.git.orig/fs/fcntl.c
> +++ linux-2.6.git/fs/fcntl.c
> @@ -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
>  	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 in
>  	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;
> Index: linux-2.6.git/include/asm-generic/fcntl.h
> ===================================================================
> --- linux-2.6.git.orig/include/asm-generic/fcntl.h
> +++ linux-2.6.git/include/asm-generic/fcntl.h
> @@ -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
> Index: linux-2.6.git/security/selinux/hooks.c
> ===================================================================
> --- linux-2.6.git.orig/security/selinux/hooks.c
> +++ linux-2.6.git/security/selinux/hooks.c
> @@ -3181,6 +3181,7 @@ static int selinux_file_fcntl(struct fil
>  	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;

Re: [PATCH] fcntl: Add F_GETOWNER_UIDS option v3

[Cyrill Gorcunov]

On Tue, Jun 05, 2012 at 09:14:58AM -0700, Eric W. Biederman wrote:
> Cyrill Gorcunov <gorcunov@openvz.org> writes:
> 
> > 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.
> 
> You want to use from_kuid_munged instead of from_kuid as you are going
> directly to userspace, and to userspace for an unmapped uid we want
> to say 65534 aka nobody instead of -1.
> 
> > v3:
> >  - rebased on Eric's kuids
> 
> To be clear this is based on my patchset that has been merged into
> v3.5-rc1.

Yeah, thanks Eric. Sure I must use _munged version here.
Updated version below. Thanks!
---
From: Cyrill Gorcunov <gorcunov@openvz.org>
Subject: fcntl: Add F_GETOWNER_UIDS option v4

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.

v4:
 - rebased to use Eric's kuid_ patchset that has been
   merged into v3.5-rc1.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
CC: "Eric W. Biederman" <ebiederm@xmission.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: "Serge E. Hallyn" <serge@hallyn.com>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Pavel Emelyanov <xemul@parallels.com>
---
 fs/fcntl.c                  |   29 +++++++++++++++++++++++++++++
 include/asm-generic/fcntl.h |    4 ++++
 security/selinux/hooks.c    |    1 +
 3 files changed, 34 insertions(+)

Index: linux-2.6.git/fs/fcntl.c
===================================================================
--- linux-2.6.git.orig/fs/fcntl.c
+++ linux-2.6.git/fs/fcntl.c
@@ -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
 	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_munged(user_ns, filp->f_owner.uid);
+	src[1] = from_kuid_munged(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 in
 	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;
Index: linux-2.6.git/include/asm-generic/fcntl.h
===================================================================
--- linux-2.6.git.orig/include/asm-generic/fcntl.h
+++ linux-2.6.git/include/asm-generic/fcntl.h
@@ -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
Index: linux-2.6.git/security/selinux/hooks.c
===================================================================
--- linux-2.6.git.orig/security/selinux/hooks.c
+++ linux-2.6.git/security/selinux/hooks.c
@@ -3181,6 +3181,7 @@ static int selinux_file_fcntl(struct fil
 	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;

Re: [PATCH] fcntl: Add F_GETOWNER_UIDS option v3

[Eric W. Biederman]

Cyrill Gorcunov <gorcunov@openvz.org> writes:

> On Tue, Jun 05, 2012 at 09:14:58AM -0700, Eric W. Biederman wrote:
>> Cyrill Gorcunov <gorcunov@openvz.org> writes:
>> 
>> > 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.
>> 
>> You want to use from_kuid_munged instead of from_kuid as you are going
>> directly to userspace, and to userspace for an unmapped uid we want
>> to say 65534 aka nobody instead of -1.
>> 
>> > v3:
>> >  - rebased on Eric's kuids
>> 
>> To be clear this is based on my patchset that has been merged into
>> v3.5-rc1.
>
> Yeah, thanks Eric. Sure I must use _munged version here.
> Updated version below. Thanks!

I don't have any strong opinions about the functionality and
I don't see any bugs so: 

Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>

> ---
> From: Cyrill Gorcunov <gorcunov@openvz.org>
> Subject: fcntl: Add F_GETOWNER_UIDS option v4
>
> 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.
>
> v4:
>  - rebased to use Eric's kuid_ patchset that has been
>    merged into v3.5-rc1.
>
> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
> CC: "Eric W. Biederman" <ebiederm@xmission.com>
> CC: Andrew Morton <akpm@linux-foundation.org>
> CC: "Serge E. Hallyn" <serge@hallyn.com>
> CC: Oleg Nesterov <oleg@redhat.com>
> CC: Pavel Emelyanov <xemul@parallels.com>
> ---
>  fs/fcntl.c                  |   29 +++++++++++++++++++++++++++++
>  include/asm-generic/fcntl.h |    4 ++++
>  security/selinux/hooks.c    |    1 +
>  3 files changed, 34 insertions(+)
>
> Index: linux-2.6.git/fs/fcntl.c
> ===================================================================
> --- linux-2.6.git.orig/fs/fcntl.c
> +++ linux-2.6.git/fs/fcntl.c
> @@ -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
>  	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_munged(user_ns, filp->f_owner.uid);
> +	src[1] = from_kuid_munged(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 in
>  	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;
> Index: linux-2.6.git/include/asm-generic/fcntl.h
> ===================================================================
> --- linux-2.6.git.orig/include/asm-generic/fcntl.h
> +++ linux-2.6.git/include/asm-generic/fcntl.h
> @@ -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
> Index: linux-2.6.git/security/selinux/hooks.c
> ===================================================================
> --- linux-2.6.git.orig/security/selinux/hooks.c
> +++ linux-2.6.git/security/selinux/hooks.c
> @@ -3181,6 +3181,7 @@ static int selinux_file_fcntl(struct fil
>  	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;

Re: [PATCH] fcntl: Add F_GETOWNER_UIDS option v3

[Andrew Morton]

On Tue, 5 Jun 2012 12:25:12 +0400
Cyrill Gorcunov <gorcunov@openvz.org> wrote:

> 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.

um, OK.

But we still have

c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-num_exe_file_vmas-removal.patch
c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-add-minimal-address-test-to-pr_set_mm.patch
c-r-prctl-add-ability-to-get-clear_tid_address.patch
c-r-prctl-drop-vma-flags-test-on-pr_set_mm_-stack-data-assignment.patch

floating about unmerged due to various unresolved issues.  Can we
please get all that stuff nailed down before working on new things?

Re: [PATCH] fcntl: Add F_GETOWNER_UIDS option v3

[Eric W. Biederman]

Andrew Morton <akpm@linux-foundation.org> writes:

> um, OK.
>
> But we still have
>
> c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-num_exe_file_vmas-removal.patch
> c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-add-minimal-address-test-to-pr_set_mm.patch
> c-r-prctl-add-ability-to-get-clear_tid_address.patch
> c-r-prctl-drop-vma-flags-test-on-pr_set_mm_-stack-data-assignment.patch
>
> floating about unmerged due to various unresolved issues.  Can we
> please get all that stuff nailed down before working on new things?

Andrew I understand the frustration but in fairness this patch is just
as old as the patches you are talking about.   Cyrill just finished
resolving the unresolved isssues with this one,  aka a conflict with
user namespace support.

Now I do agree that we need to finish the rest of these things.

Eric

Re: [PATCH] fcntl: Add F_GETOWNER_UIDS option v3

[Cyrill Gorcunov]

On Tue, Jun 05, 2012 at 03:47:43PM -0700, Andrew Morton wrote:
> > 
> > This option is valid iif CONFIG_CHECKPOINT_RESTORE
> > is turned on, otherwise returning -EINVAL.
> 
> um, OK.
> 
> But we still have
> 
> c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-num_exe_file_vmas-removal.patch
> c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-add-minimal-address-test-to-pr_set_mm.patch
> c-r-prctl-add-ability-to-get-clear_tid_address.patch
> c-r-prctl-drop-vma-flags-test-on-pr_set_mm_-stack-data-assignment.patch
> 
> floating about unmerged due to various unresolved issues.  Can we
> please get all that stuff nailed down before working on new things?

Hmm, Andrew, I must admit I don't understand which unresolved issues
here with the rest of prctl SET_MM code. Could you please clarify?
Do they not apply on current linux-next, or something like that?

	Cyrill