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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: Michal Clapinski <mclapinski@google.com>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Reviewed-by: Manfred Spraul <manfred@colorfullife.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michal Clapinski 2021-11-08 18:35:59 -08:00 committed by Linus Torvalds
parent 303f8e2d02
commit 5563cabdde
1 changed files with 23 additions and 6 deletions
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29
ipc/ipc_sysctl.c
View File

@ -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,
},