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authorAlexey Gladkov <legion@kernel.org>2022-05-03 15:39:56 +0200
committerEric W. Biederman <ebiederm@xmission.com>2022-05-03 17:25:58 -0500
commit0889f44e281034e180daa6daf3e2d57c012452d4 (patch)
treeb5a178a44464035f58e926b1d9ebed9a8880d4ad
parentdd141a4955d5ebbb3f4c7996796e86a3ac9ed57f (diff)
ipc: Check permissions for checkpoint_restart sysctls at open time
As Eric Biederman pointed out, it is possible not to use a custom proc_handler and check permissions for every write, but to use a .permission handler. That will allow the checkpoint_restart sysctls to perform all of their permission checks at open time, and not need any other special code. Link: https://lore.kernel.org/lkml/87czib9g38.fsf@email.froward.int.ebiederm.org/ Fixes: 1f5c135ee509 ("ipc: Store ipc sysctls in the ipc namespace") Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Alexey Gladkov <legion@kernel.org> Link: https://lkml.kernel.org/r/65fa8459803830608da4610a39f33c76aa933eb9.1651584847.git.legion@kernel.org Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
-rw-r--r--ipc/ipc_sysctl.c57
1 files changed, 29 insertions, 28 deletions
diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index eb7ba8e0a355..5a58598d48c8 100644
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -68,25 +68,6 @@ 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 ipc_namespace *ns = table->extra1;
- struct ctl_table ipc_table;
-
- if (write && !checkpoint_restore_ns_capable(ns->user_ns))
- return -EPERM;
-
- memcpy(&ipc_table, table, sizeof(ipc_table));
-
- ipc_table.extra1 = SYSCTL_ZERO;
- ipc_table.extra2 = SYSCTL_INT_MAX;
-
- return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
-}
-#endif
-
int ipc_mni = IPCMNI;
int ipc_mni_shift = IPCMNI_SHIFT;
int ipc_min_cycle = RADIX_TREE_MAP_SIZE;
@@ -172,22 +153,28 @@ static struct ctl_table ipc_sysctls[] = {
.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 = 0666,
- .proc_handler = proc_ipc_dointvec_minmax_checkpoint_restore,
+ .mode = 0444,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_INT_MAX,
},
{
.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 = 0666,
- .proc_handler = proc_ipc_dointvec_minmax_checkpoint_restore,
+ .mode = 0444,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_INT_MAX,
},
{
.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 = 0666,
- .proc_handler = proc_ipc_dointvec_minmax_checkpoint_restore,
+ .mode = 0444,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_INT_MAX,
},
#endif
{}
@@ -203,8 +190,25 @@ static int set_is_seen(struct ctl_table_set *set)
return &current->nsproxy->ipc_ns->ipc_set == set;
}
+static int ipc_permissions(struct ctl_table_header *head, struct ctl_table *table)
+{
+ int mode = table->mode;
+
+#ifdef CONFIG_CHECKPOINT_RESTORE
+ struct ipc_namespace *ns = current->nsproxy->ipc_ns;
+
+ if (((table->data == &ns->ids[IPC_SEM_IDS].next_id) ||
+ (table->data == &ns->ids[IPC_MSG_IDS].next_id) ||
+ (table->data == &ns->ids[IPC_SHM_IDS].next_id)) &&
+ checkpoint_restore_ns_capable(ns->user_ns))
+ mode = 0666;
+#endif
+ return mode;
+}
+
static struct ctl_table_root set_root = {
.lookup = set_lookup,
+ .permissions = ipc_permissions,
};
bool setup_ipc_sysctls(struct ipc_namespace *ns)
@@ -244,15 +248,12 @@ bool setup_ipc_sysctls(struct ipc_namespace *ns)
#ifdef CONFIG_CHECKPOINT_RESTORE
} else if (tbl[i].data == &init_ipc_ns.ids[IPC_SEM_IDS].next_id) {
tbl[i].data = &ns->ids[IPC_SEM_IDS].next_id;
- tbl[i].extra1 = ns;
} else if (tbl[i].data == &init_ipc_ns.ids[IPC_MSG_IDS].next_id) {
tbl[i].data = &ns->ids[IPC_MSG_IDS].next_id;
- tbl[i].extra1 = ns;
} else if (tbl[i].data == &init_ipc_ns.ids[IPC_SHM_IDS].next_id) {
tbl[i].data = &ns->ids[IPC_SHM_IDS].next_id;
- tbl[i].extra1 = ns;
#endif
} else {
tbl[i].data = NULL;