Commit 5563cabd authored by Michal Clapinski's avatar Michal Clapinski Committed by Linus Torvalds
Browse files

ipc: check checkpoint_restore_ns_capable() to modify C/R proc files 

This commit removes the requirement to be root to modify sem_next_id,
msg_next_id and shm_next_id and checks checkpoint_restore_ns_capable
instead.

Since those files are specific to the IPC namespace, there is no reason
they should require root privileges.  This is similar to ns_last_pid,
which also only checks checkpoint_restore_ns_capable.

[akpm@linux-foundation.org: ipc/ipc_sysctl.c needs capability.h for checkpoint_restore_ns_capable()]

Link: https://lkml.kernel.org/r/20210916163717.3179496-1-mclapinski@google.com


Signed-off-by: default avatarMichal Clapinski <mclapinski@google.com>
Reviewed-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Reviewed-by: default avatarManfred Spraul <manfred@colorfullife.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 303f8e2d

ipc/ipc_sysctl.c

+23 −6
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/nsproxy.h>

#include <linux/sysctl.h>

#include <linux/uaccess.h>

#include <linux/capability.h>

#include <linux/ipc_namespace.h>

#include <linux/msg.h>

#include "util.h"
@@ -104,6 +105,19 @@ static int proc_ipc_sem_dointvec(struct ctl_table *table, int write, 
	return ret;

}



#ifdef CONFIG_CHECKPOINT_RESTORE

static int proc_ipc_dointvec_minmax_checkpoint_restore(struct ctl_table *table,

		int write, void *buffer, size_t *lenp, loff_t *ppos)

{

	struct user_namespace *user_ns = current->nsproxy->ipc_ns->user_ns;



	if (write && !checkpoint_restore_ns_capable(user_ns))

		return -EPERM;



	return proc_ipc_dointvec_minmax(table, write, buffer, lenp, ppos);

}

#endif



#else

#define proc_ipc_doulongvec_minmax NULL

#define proc_ipc_dointvec	   NULL
@@ -111,6 +125,9 @@ static int proc_ipc_sem_dointvec(struct ctl_table *table, int write, 
#define proc_ipc_dointvec_minmax_orphans   NULL

#define proc_ipc_auto_msgmni	   NULL

#define proc_ipc_sem_dointvec	   NULL

#ifdef CONFIG_CHECKPOINT_RESTORE

#define proc_ipc_dointvec_minmax_checkpoint_restore	NULL

#endif	/* CONFIG_CHECKPOINT_RESTORE */

#endif



int ipc_mni = IPCMNI;
@@ -198,8 +215,8 @@ static struct ctl_table ipc_kern_table[] = { 
		.procname	= "sem_next_id",

		.data		= &init_ipc_ns.ids[IPC_SEM_IDS].next_id,

		.maxlen		= sizeof(init_ipc_ns.ids[IPC_SEM_IDS].next_id),

		.mode		= 0644,

		.proc_handler	= proc_ipc_dointvec_minmax,

		.mode		= 0666,

		.proc_handler	= proc_ipc_dointvec_minmax_checkpoint_restore,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_INT_MAX,

	},
@@ -207,8 +224,8 @@ static struct ctl_table ipc_kern_table[] = { 
		.procname	= "msg_next_id",

		.data		= &init_ipc_ns.ids[IPC_MSG_IDS].next_id,

		.maxlen		= sizeof(init_ipc_ns.ids[IPC_MSG_IDS].next_id),

		.mode		= 0644,

		.proc_handler	= proc_ipc_dointvec_minmax,

		.mode		= 0666,

		.proc_handler	= proc_ipc_dointvec_minmax_checkpoint_restore,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_INT_MAX,

	},
@@ -216,8 +233,8 @@ static struct ctl_table ipc_kern_table[] = { 
		.procname	= "shm_next_id",

		.data		= &init_ipc_ns.ids[IPC_SHM_IDS].next_id,

		.maxlen		= sizeof(init_ipc_ns.ids[IPC_SHM_IDS].next_id),

		.mode		= 0644,

		.proc_handler	= proc_ipc_dointvec_minmax,

		.mode		= 0666,

		.proc_handler	= proc_ipc_dointvec_minmax_checkpoint_restore,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_INT_MAX,

	},