Re: [ckrm-tech] [RFC][PATCH 4/7] UBC: syscalls (user interface)

[Matt Helsley <matthltc@us.ibm.com>]

On Wed, 2006-08-16 at 19:39 +0400, Kirill Korotaev wrote:
> Add the following system calls for UB management:
>   1. sys_getluid    - get current UB id
>   2. sys_setluid    - changes exec_ and fork_ UBs on current
>   3. sys_setublimit - set limits for resources consumtions
> 
> Signed-Off-By: Pavel Emelianov <xemul@sw.ru>
> Signed-Off-By: Kirill Korotaev <dev@sw.ru>
> 
> ---
>  arch/i386/kernel/syscall_table.S |    3
>  arch/ia64/kernel/entry.S         |    3
>  arch/sparc/kernel/systbls.S      |    2
>  arch/sparc64/kernel/systbls.S    |    2
>  include/asm-i386/unistd.h        |    5 +
>  include/asm-ia64/unistd.h        |    5 +
>  include/asm-powerpc/systbl.h     |    3
>  include/asm-powerpc/unistd.h     |    5 +
>  include/asm-sparc/unistd.h       |    3
>  include/asm-sparc64/unistd.h     |    3
>  include/asm-x86_64/unistd.h      |    8 ++
>  kernel/ub/Makefile               |    1
>  kernel/ub/sys.c                  |  126 +++++++++++++++++++++++++++++++++++++++
>  13 files changed, 163 insertions(+), 6 deletions(-)
> 
> --- ./arch/i386/kernel/syscall_table.S.ubsys	2006-07-10 12:39:10.000000000 +0400
> +++ ./arch/i386/kernel/syscall_table.S	2006-07-31 14:36:59.000000000 +0400
> @@ -317,3 +317,6 @@ ENTRY(sys_call_table)
>  	.long sys_vmsplice
>  	.long sys_move_pages
>  	.long sys_getcpu
> +	.long sys_getluid
> +	.long sys_setluid
> +	.long sys_setublimit		/* 320 */
> --- ./arch/ia64/kernel/entry.S.ubsys	2006-07-10 12:39:10.000000000 +0400
> +++ ./arch/ia64/kernel/entry.S	2006-07-31 15:25:36.000000000 +0400
> @@ -1610,5 +1610,8 @@ sys_call_table:
>  	data8 sys_sync_file_range		// 1300
>  	data8 sys_tee
>  	data8 sys_vmsplice
> +	daat8 sys_getluid
> +	data8 sys_setluid
> +	data8 sys_setublimit			// 1305
>  
>  	.org sys_call_table + 8*NR_syscalls	// guard against failures to increase NR_syscalls
> --- ./arch/sparc/kernel/systbls.S.arsys	2006-07-10 12:39:10.000000000 +0400
> +++ ./arch/sparc/kernel/systbls.S	2006-08-10 17:07:15.000000000 +0400
> @@ -78,7 +78,7 @@ sys_call_table:
>  /*285*/	.long sys_mkdirat, sys_mknodat, sys_fchownat, sys_futimesat, sys_fstatat64
>  /*290*/	.long sys_unlinkat, sys_renameat, sys_linkat, sys_symlinkat, sys_readlinkat
>  /*295*/	.long sys_fchmodat, sys_faccessat, sys_pselect6, sys_ppoll, sys_unshare
> -/*300*/	.long sys_set_robust_list, sys_get_robust_list
> +/*300*/	.long sys_set_robust_list, sys_get_robust_list, sys_getluid, sys_setluid, sys_setublimit
>  
>  #ifdef CONFIG_SUNOS_EMUL
>  	/* Now the SunOS syscall table. */
> --- ./arch/sparc64/kernel/systbls.S.arsys	2006-07-10 12:39:11.000000000 +0400
> +++ ./arch/sparc64/kernel/systbls.S	2006-08-10 17:08:52.000000000 +0400
> @@ -79,7 +79,7 @@ sys_call_table32:
>  	.word sys_mkdirat, sys_mknodat, sys_fchownat, compat_sys_futimesat, compat_sys_fstatat64
>  /*290*/	.word sys_unlinkat, sys_renameat, sys_linkat, sys_symlinkat, sys_readlinkat
>  	.word sys_fchmodat, sys_faccessat, compat_sys_pselect6, compat_sys_ppoll, sys_unshare
> -/*300*/	.word compat_sys_set_robust_list, compat_sys_get_robust_list
> +/*300*/	.word compat_sys_set_robust_list, compat_sys_get_robust_list, sys_getluid, sys_setluid, sys_setublimit
>  
>  #endif /* CONFIG_COMPAT */
>  
> --- ./include/asm-i386/unistd.h.ubsys	2006-07-10 12:39:19.000000000 +0400
> +++ ./include/asm-i386/unistd.h	2006-07-31 15:56:31.000000000 +0400
> @@ -323,10 +323,13 @@
>  #define __NR_vmsplice		316
>  #define __NR_move_pages		317
>  #define __NR_getcpu		318
> +#define __NR_getluid		319
> +#define __NR_setluid		320
> +#define __NR_setublimit		321
>  
>  #ifdef __KERNEL__
>  
> -#define NR_syscalls 318
> +#define NR_syscalls 322
>  #include <linux/err.h>
>  
>  /*
> --- ./include/asm-ia64/unistd.h.ubsys	2006-07-10 12:39:19.000000000 +0400
> +++ ./include/asm-ia64/unistd.h	2006-07-31 15:57:23.000000000 +0400
> @@ -291,11 +291,14 @@
>  #define __NR_sync_file_range		1300
>  #define __NR_tee			1301
>  #define __NR_vmsplice			1302
> +#define __NR_getluid			1303
> +#define __NR_setluid			1304
> +#define __NR_setublimit			1305
>  
>  #ifdef __KERNEL__
>  
> 
> -#define NR_syscalls			279 /* length of syscall table */
> +#define NR_syscalls			282 /* length of syscall table */
>  
>  #define __ARCH_WANT_SYS_RT_SIGACTION
>  
> --- ./include/asm-powerpc/systbl.h.arsys	2006-07-10 12:39:19.000000000 +0400
> +++ ./include/asm-powerpc/systbl.h	2006-08-10 17:05:53.000000000 +0400
> @@ -304,3 +304,6 @@ SYSCALL_SPU(fchmodat)
>  SYSCALL_SPU(faccessat)
>  COMPAT_SYS_SPU(get_robust_list)
>  COMPAT_SYS_SPU(set_robust_list)
> +SYSCALL(sys_getluid)
> +SYSCALL(sys_setluid)
> +SYSCALL(sys_setublimit)
> --- ./include/asm-powerpc/unistd.h.arsys	2006-07-10 12:39:19.000000000 +0400
> +++ ./include/asm-powerpc/unistd.h	2006-08-10 17:06:28.000000000 +0400
> @@ -323,10 +323,13 @@
>  #define __NR_faccessat		298
>  #define __NR_get_robust_list	299
>  #define __NR_set_robust_list	300
> +#define __NR_getluid		301
> +#define __NR_setluid		302
> +#define __NR_setublimit		303
>  
>  #ifdef __KERNEL__
>  
> -#define __NR_syscalls		301
> +#define __NR_syscalls		304
>  
>  #define __NR__exit __NR_exit
>  #define NR_syscalls	__NR_syscalls
> --- ./include/asm-sparc/unistd.h.arsys	2006-07-10 12:39:19.000000000 +0400
> +++ ./include/asm-sparc/unistd.h	2006-08-10 17:08:19.000000000 +0400
> @@ -318,6 +318,9 @@
>  #define __NR_unshare		299
>  #define __NR_set_robust_list	300
>  #define __NR_get_robust_list	301
> +#define __NR_getluid		302
> +#define __NR_setluid		303
> +#define __NR_setublimit		304
>  
>  #ifdef __KERNEL__
>  /* WARNING: You MAY NOT add syscall numbers larger than 301, since
> --- ./include/asm-sparc64/unistd.h.arsys	2006-07-10 12:39:19.000000000 +0400
> +++ ./include/asm-sparc64/unistd.h	2006-08-10 17:09:24.000000000 +0400
> @@ -320,6 +320,9 @@
>  #define __NR_unshare		299
>  #define __NR_set_robust_list	300
>  #define __NR_get_robust_list	301
> +#define __NR_getluid		302
> +#define __NR_setluid		303
> +#define __NR_setublimit		304
>  
>  #ifdef __KERNEL__
>  /* WARNING: You MAY NOT add syscall numbers larger than 301, since
> --- ./include/asm-x86_64/unistd.h.ubsys	2006-07-10 12:39:19.000000000 +0400
> +++ ./include/asm-x86_64/unistd.h	2006-07-31 16:00:01.000000000 +0400
> @@ -619,10 +619,16 @@ __SYSCALL(__NR_sync_file_range, sys_sync
>  __SYSCALL(__NR_vmsplice, sys_vmsplice)
>  #define __NR_move_pages		279
>  __SYSCALL(__NR_move_pages, sys_move_pages)
> +#define __NR_getluid		280
> +__SYSCALL(__NR_getluid, sys_getluid)
> +#define __NR_setluid		281
> +__SYSCALL(__NR_setluid, sys_setluid)
> +#define __NR_setublimit		282
> +__SYSCALL(__NR_setublimit, sys_setublimit)
>  
>  #ifdef __KERNEL__
>  
> -#define __NR_syscall_max __NR_move_pages
> +#define __NR_syscall_max __NR_setublimit
>  #include <linux/err.h>
>  
>  #ifndef __NO_STUBS
> --- ./kernel/ub/Makefile.ubsys	2006-07-28 14:08:37.000000000 +0400
> +++ ./kernel/ub/Makefile	2006-08-01 11:08:39.000000000 +0400
> @@ -6,3 +6,4 @@
>  
>  obj-$(CONFIG_USER_RESOURCE) += beancounter.o
>  obj-$(CONFIG_USER_RESOURCE) += misc.o
> +obj-y += sys.o
> --- ./kernel/ub/sys.c.ubsys	2006-07-28 18:52:18.000000000 +0400
> +++ ./kernel/ub/sys.c	2006-08-03 16:14:23.000000000 +0400
> @@ -0,0 +1,126 @@
> +/*
> + *  kernel/ub/sys.c
> + *
> + *  Copyright (C) 2006 OpenVZ. SWsoft Inc
> + *
> + */
> +
> +#include <linux/config.h>
> +#include <linux/sched.h>
> +#include <asm/uaccess.h>
> +
> +#include <ub/beancounter.h>
> +#include <ub/task.h>
> +
> +#ifndef CONFIG_USER_RESOURCE

Get rid of the #ifdef since this file should only be compiled if
CONFIG_USER_RESOURCE=y anyway.

> +asmlinkage long sys_getluid(void)
> +{
> +	return -ENOSYS;
> +}
> +
> +asmlinkage long sys_setluid(uid_t uid)
> +{
> +	return -ENOSYS;
> +}
> +
> +asmlinkage long sys_setublimit(uid_t uid, unsigned long resource, 
> +		unsigned long *limits)
> +{
> +	return -ENOSYS;
> +}

Looks to me like you want to add:

cond_syscall(sys_getluid);
...

in kernel/sys_ni.c and then you won't have to worry about making these
empty functions.

> +#else /* CONFIG_USER_RESOURCE */
> +
> +/*
> + *	The (rather boring) getluid syscall
> + */
> +asmlinkage long sys_getluid(void)
> +{
> +	struct user_beancounter *ub;
> +
> +	ub = get_exec_ub();
> +	if (ub == NULL)
> +		return -EINVAL;
> +
> +	return ub->ub_uid;
> +}
> +
> +/*
> + *	The setluid syscall
> + */
> +asmlinkage long sys_setluid(uid_t uid)
> +{
> +	int error;
> +	struct user_beancounter *ub;
> +	struct task_beancounter *task_bc;
> +
> +	task_bc = &current->task_bc;
> +
> +	/* You may not disown a setluid */
> +	error = -EINVAL;
> +	if (uid == (uid_t)-1)
> +		goto out;
> +
> +	/* You may only set an ub as root */
> +	error = -EPERM;
> +	if (!capable(CAP_SETUID))
> +		goto out;

With resource groups you don't necessarily have to be root -- just the
owner of the group and task. 

Filesystems and appropriate share representations offer a way to give
regular users the ability to manage their resources without requiring
CAP_FOO.

> +	/* Ok - set up a beancounter entry for this user */
> +	error = -ENOBUFS;
> +	ub = beancounter_findcreate(uid, NULL, UB_ALLOC);
> +	if (ub == NULL)
> +		goto out;
> +
> +	/* install bc */
> +	put_beancounter(task_bc->exec_ub);
> +	task_bc->exec_ub = ub;
> +	put_beancounter(task_bc->fork_sub);
> +	task_bc->fork_sub = get_beancounter(ub);
> +	error = 0;
> +out:
> +	return error;
> +}
> +
> +/*
> + *	The setbeanlimit syscall
> + */
> +asmlinkage long sys_setublimit(uid_t uid, unsigned long resource,
> +		unsigned long *limits)
> +{
> +	int error;
> +	unsigned long flags;
> +	struct user_beancounter *ub;
> +	unsigned long new_limits[2];
> +
> +	error = -EPERM;
> +	if(!capable(CAP_SYS_RESOURCE))
> +		goto out;

Again, a filesystem interface would give us more flexibility when it
comes to allowing users to manage their resources while still preventing
them from exceeding limits.

I doubt you really want to give owners of a container CAP_SYS_RESOURCE
and CAP_USER (i.e. total control over resource management) just to allow
them to manage their subset of the resources.

> +	error = -EINVAL;
> +	if (resource >= UB_RESOURCES)
> +		goto out;
> +
> +	error = -EFAULT;
> +	if (copy_from_user(&new_limits, limits, sizeof(new_limits)))
> +		goto out;
> +
> +	error = -EINVAL;
> +	if (new_limits[0] > UB_MAXVALUE || new_limits[1] > UB_MAXVALUE)
> +		goto out;
> +
> +	error = -ENOENT;
> +	ub = beancounter_findcreate(uid, NULL, 0);
> +	if (ub == NULL)
> +		goto out;
> +
> +	spin_lock_irqsave(&ub->ub_lock, flags);
> +	ub->ub_parms[resource].barrier = new_limits[0];
> +	ub->ub_parms[resource].limit = new_limits[1];
> +	spin_unlock_irqrestore(&ub->ub_lock, flags);
> +
> +	put_beancounter(ub);
> +	error = 0;
> +out:
> +	return error;
> +}
> +#endif
> 
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