[RFC PATCH v1 06/30] sysctl: ipc: use sysctl_field in ipc_sysctl
From: Alexey Gladkov
Date: Wed Aug 26 2026 - 15:50:07 EST
IPC clones its sysctl table for each namespace so registration can
rewrite data pointers from init_ipc_ns to the target namespace. The
cloned table then has to stay alive until namespace teardown only so it
can be freed after unregistering the sysctls.
Use sysctl_field to derive IPC namespace data from the registration
context instead. This keeps the sysctl descriptors static and const, and
removes the per-namespace table copy and unregister-time free.
Keep the IPC-specific handlers responsible for their own min/max bounds
so the conversion does not need to extend the generic custom field
interface.
Signed-off-by: Alexey Gladkov <legion@xxxxxxxxxx>
---
ipc/ipc_sysctl.c | 256 ++++++++++++++++++-----------------------------
1 file changed, 98 insertions(+), 158 deletions(-)
diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index 9b087ebeb643..7b85b0f5ef82 100644
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -13,7 +13,6 @@
#include <linux/capability.h>
#include <linux/ipc_namespace.h>
#include <linux/msg.h>
-#include <linux/slab.h>
#include <linux/cred.h>
#include "util.h"
@@ -48,6 +47,10 @@ static int proc_ipc_auto_msgmni(const struct ctl_table *table, int write,
return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
}
+int ipc_mni = IPCMNI;
+int ipc_mni_shift = IPCMNI_SHIFT;
+int ipc_min_cycle = RADIX_TREE_MAP_SIZE;
+
static int proc_ipc_sem_dointvec(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
@@ -69,117 +72,100 @@ static int proc_ipc_sem_dointvec(const struct ctl_table *table, int write,
return ret;
}
-int ipc_mni = IPCMNI;
-int ipc_mni_shift = IPCMNI_SHIFT;
-int ipc_min_cycle = RADIX_TREE_MAP_SIZE;
+#define IPC_DATA(type, field) \
+static type *ipc_ ## field ## _data(const struct sysctl_context *ctx) \
+{ \
+ return &ctx->ns.ipc_ns->field; \
+}
+
+IPC_DATA(void, shm_ctlmax)
+IPC_DATA(void, shm_ctlall)
+IPC_DATA(int, shm_ctlmni)
+IPC_DATA(void, shm_rmid_forced)
+IPC_DATA(void, msg_ctlmax)
+IPC_DATA(void, msg_ctlmni)
+IPC_DATA(void, msg_ctlmnb)
+IPC_DATA(void, sem_ctls)
+
+#define IPC_LIMIT(name, value) \
+static void *ipc_ ## name ## _limit(const struct sysctl_context *ctx) \
+{ \
+ return value; \
+}
+
+IPC_LIMIT(zero, SYSCTL_ZERO)
+IPC_LIMIT(one, SYSCTL_ONE)
+IPC_LIMIT(int_max, SYSCTL_INT_MAX)
+IPC_LIMIT(mni, &ipc_mni)
+
+#define IPC_FIELD_CUSTOM_MINMAX(_procname, _len, _data, _handler, _min, _max) \
+ { \
+ .procname = (_procname), \
+ .mode = 0644, \
+ .type = SYSCTL_FIELD_CUSTOM, \
+ .ctl_custom = { \
+ .proc_handler = (_handler), \
+ .maxlen = (_len), \
+ .data = (_data), \
+ .extra1 = (_min), \
+ .extra2 = (_max), \
+ }, \
+ }
-static const struct ctl_table ipc_sysctls[] = {
- {
- .procname = "shmmax",
- .data = &init_ipc_ns.shm_ctlmax,
- .maxlen = sizeof(init_ipc_ns.shm_ctlmax),
- .mode = 0644,
- .proc_handler = proc_doulongvec_minmax,
- },
- {
- .procname = "shmall",
- .data = &init_ipc_ns.shm_ctlall,
- .maxlen = sizeof(init_ipc_ns.shm_ctlall),
- .mode = 0644,
- .proc_handler = proc_doulongvec_minmax,
- },
- {
- .procname = "shmmni",
- .data = &init_ipc_ns.shm_ctlmni,
- .maxlen = sizeof(init_ipc_ns.shm_ctlmni),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
- .extra2 = &ipc_mni,
- },
- {
- .procname = "shm_rmid_forced",
- .data = &init_ipc_ns.shm_rmid_forced,
- .maxlen = sizeof(init_ipc_ns.shm_rmid_forced),
- .mode = 0644,
- .proc_handler = proc_ipc_dointvec_minmax_orphans,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_ONE,
- },
- {
- .procname = "msgmax",
- .data = &init_ipc_ns.msg_ctlmax,
- .maxlen = sizeof(init_ipc_ns.msg_ctlmax),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_INT_MAX,
- },
- {
- .procname = "msgmni",
- .data = &init_ipc_ns.msg_ctlmni,
- .maxlen = sizeof(init_ipc_ns.msg_ctlmni),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
- .extra2 = &ipc_mni,
- },
- {
- .procname = "auto_msgmni",
- .data = NULL,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_ipc_auto_msgmni,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_ONE,
- },
- {
- .procname = "msgmnb",
- .data = &init_ipc_ns.msg_ctlmnb,
- .maxlen = sizeof(init_ipc_ns.msg_ctlmnb),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_INT_MAX,
- },
- {
- .procname = "sem",
- .data = &init_ipc_ns.sem_ctls,
- .maxlen = 4*sizeof(int),
- .mode = 0644,
- .proc_handler = proc_ipc_sem_dointvec,
- },
#ifdef CONFIG_CHECKPOINT_RESTORE
- {
- .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 = 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 = 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 = 0444,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_INT_MAX,
- },
+#define IPC_ID_NEXT_DATA(name, id) \
+static int *ipc_ ## name ## _data(const struct sysctl_context *ctx) \
+{ \
+ return &ctx->ns.ipc_ns->ids[id].next_id; \
+}
+
+IPC_ID_NEXT_DATA(sem_next_id, IPC_SEM_IDS)
+IPC_ID_NEXT_DATA(msg_next_id, IPC_MSG_IDS)
+IPC_ID_NEXT_DATA(shm_next_id, IPC_SHM_IDS)
+#endif
+
+static const struct sysctl_field ipc_sysctls[] = {
+ SYSCTL_FIELD_CUSTOM("shmmax", 0644, sizeof(init_ipc_ns.shm_ctlmax),
+ ipc_shm_ctlmax_data, proc_doulongvec_minmax),
+ SYSCTL_FIELD_CUSTOM("shmall", 0644, sizeof(init_ipc_ns.shm_ctlall),
+ ipc_shm_ctlall_data, proc_doulongvec_minmax),
+ SYSCTL_FIELD_STATIC_INT_MINMAX("shmmni", 0644, ipc_shm_ctlmni_data,
+ SYSCTL_ZERO, &ipc_mni),
+ IPC_FIELD_CUSTOM_MINMAX("shm_rmid_forced",
+ sizeof(init_ipc_ns.shm_rmid_forced),
+ ipc_shm_rmid_forced_data,
+ proc_ipc_dointvec_minmax_orphans,
+ ipc_zero_limit, ipc_one_limit),
+ IPC_FIELD_CUSTOM_MINMAX("msgmax", sizeof(init_ipc_ns.msg_ctlmax),
+ ipc_msg_ctlmax_data, proc_dointvec_minmax,
+ ipc_zero_limit, ipc_int_max_limit),
+ IPC_FIELD_CUSTOM_MINMAX("msgmni", sizeof(init_ipc_ns.msg_ctlmni),
+ ipc_msg_ctlmni_data, proc_dointvec_minmax,
+ ipc_zero_limit, ipc_mni_limit),
+ IPC_FIELD_CUSTOM_MINMAX("auto_msgmni", sizeof(int), NULL,
+ proc_ipc_auto_msgmni,
+ ipc_zero_limit, ipc_one_limit),
+ IPC_FIELD_CUSTOM_MINMAX("msgmnb", sizeof(init_ipc_ns.msg_ctlmnb),
+ ipc_msg_ctlmnb_data, proc_dointvec_minmax,
+ ipc_zero_limit, ipc_int_max_limit),
+ SYSCTL_FIELD_CUSTOM("sem", 0644, 4 * sizeof(int), ipc_sem_ctls_data,
+ proc_ipc_sem_dointvec),
+#ifdef CONFIG_CHECKPOINT_RESTORE
+ SYSCTL_FIELD_STATIC_INT_MINMAX("sem_next_id", 0444,
+ ipc_sem_next_id_data, SYSCTL_ZERO,
+ SYSCTL_INT_MAX),
+ SYSCTL_FIELD_STATIC_INT_MINMAX("msg_next_id", 0444,
+ ipc_msg_next_id_data, SYSCTL_ZERO,
+ SYSCTL_INT_MAX),
+ SYSCTL_FIELD_STATIC_INT_MINMAX("shm_next_id", 0444,
+ ipc_shm_next_id_data, SYSCTL_ZERO,
+ SYSCTL_INT_MAX),
#endif
};
+#undef IPC_FIELD_CUSTOM_MINMAX
+#undef IPC_LIMIT
+
static struct ctl_table_set *set_lookup(struct ctl_table_root *root)
{
return ¤t->nsproxy->ipc_ns->ipc_set;
@@ -244,57 +230,15 @@ static struct ctl_table_root set_root = {
bool setup_ipc_sysctls(struct ipc_namespace *ns)
{
- struct ctl_table *tbl;
+ struct sysctl_context ctx = {
+ .ns.ipc_ns = ns,
+ };
setup_sysctl_set(&ns->ipc_set, &set_root, set_is_seen);
- tbl = kmemdup(ipc_sysctls, sizeof(ipc_sysctls), GFP_KERNEL);
- if (tbl) {
- int i;
-
- for (i = 0; i < ARRAY_SIZE(ipc_sysctls); i++) {
- if (tbl[i].data == &init_ipc_ns.shm_ctlmax)
- tbl[i].data = &ns->shm_ctlmax;
-
- else if (tbl[i].data == &init_ipc_ns.shm_ctlall)
- tbl[i].data = &ns->shm_ctlall;
-
- else if (tbl[i].data == &init_ipc_ns.shm_ctlmni)
- tbl[i].data = &ns->shm_ctlmni;
-
- else if (tbl[i].data == &init_ipc_ns.shm_rmid_forced)
- tbl[i].data = &ns->shm_rmid_forced;
-
- else if (tbl[i].data == &init_ipc_ns.msg_ctlmax)
- tbl[i].data = &ns->msg_ctlmax;
-
- else if (tbl[i].data == &init_ipc_ns.msg_ctlmni)
- tbl[i].data = &ns->msg_ctlmni;
-
- else if (tbl[i].data == &init_ipc_ns.msg_ctlmnb)
- tbl[i].data = &ns->msg_ctlmnb;
-
- else if (tbl[i].data == &init_ipc_ns.sem_ctls)
- tbl[i].data = &ns->sem_ctls;
-#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;
-
- else if (tbl[i].data == &init_ipc_ns.ids[IPC_MSG_IDS].next_id)
- tbl[i].data = &ns->ids[IPC_MSG_IDS].next_id;
-
- else if (tbl[i].data == &init_ipc_ns.ids[IPC_SHM_IDS].next_id)
- tbl[i].data = &ns->ids[IPC_SHM_IDS].next_id;
-#endif
- else
- tbl[i].data = NULL;
- }
-
- ns->ipc_sysctls = __register_sysctl_table(&ns->ipc_set, "kernel", tbl,
- ARRAY_SIZE(ipc_sysctls));
- }
+ ns->ipc_sysctls = register_sysctl_fields(&ns->ipc_set, "kernel",
+ ipc_sysctls, &ctx);
if (!ns->ipc_sysctls) {
- kfree(tbl);
retire_sysctl_set(&ns->ipc_set);
return false;
}
@@ -304,12 +248,8 @@ bool setup_ipc_sysctls(struct ipc_namespace *ns)
void retire_ipc_sysctls(struct ipc_namespace *ns)
{
- const struct ctl_table *tbl;
-
- tbl = ns->ipc_sysctls->ctl_table_arg;
unregister_sysctl_table(ns->ipc_sysctls);
retire_sysctl_set(&ns->ipc_set);
- kfree(tbl);
}
static int __init ipc_sysctl_init(void)
--
2.55.0