diff options
| -rw-r--r-- | include/linux/ipc_namespace.h | 1 | ||||
| -rw-r--r-- | include/linux/notifier.h | 4 | ||||
| -rw-r--r-- | ipc/ipc_sysctl.c | 45 | ||||
| -rw-r--r-- | ipc/ipcns_notifier.c | 9 | ||||
| -rw-r--r-- | kernel/notifier.c | 38 |
5 files changed, 87 insertions, 10 deletions
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h index c3b1da9..ea6c18a 100644 --- a/include/linux/ipc_namespace.h +++ b/include/linux/ipc_namespace.h @@ -52,6 +52,7 @@ extern atomic_t nr_ipc_ns; #define INIT_IPC_NS(ns) .ns = &init_ipc_ns, extern int register_ipcns_notifier(struct ipc_namespace *); +extern int cond_register_ipcns_notifier(struct ipc_namespace *); extern int unregister_ipcns_notifier(struct ipc_namespace *); extern int ipcns_notify(unsigned long); diff --git a/include/linux/notifier.h b/include/linux/notifier.h index 20dfed5..0ff6224 100644 --- a/include/linux/notifier.h +++ b/include/linux/notifier.h @@ -121,6 +121,10 @@ extern int raw_notifier_chain_register(struct raw_notifier_head *nh, extern int srcu_notifier_chain_register(struct srcu_notifier_head *nh, struct notifier_block *nb); +extern int blocking_notifier_chain_cond_register( + struct blocking_notifier_head *nh, + struct notifier_block *nb); + extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh, struct notifier_block *nb); extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh, diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c index d12ff5c..d349746 100644 --- a/ipc/ipc_sysctl.c +++ b/ipc/ipc_sysctl.c @@ -15,6 +15,8 @@ #include <linux/sysctl.h> #include <linux/uaccess.h> #include <linux/ipc_namespace.h> +#include <linux/msg.h> +#include "util.h" static void *get_ipc(ctl_table *table) { @@ -24,6 +26,27 @@ static void *get_ipc(ctl_table *table) return which; } +/* + * Routine that is called when a tunable has successfully been changed by + * hand and it has a callback routine registered on the ipc namespace notifier + * chain: we don't want such tunables to be recomputed anymore upon memory + * add/remove or ipc namespace creation/removal. + * They can come back to a recomputable state by being set to a <0 value. + */ +static void tunable_set_callback(int val) +{ + if (val >= 0) + unregister_ipcns_notifier(current->nsproxy->ipc_ns); + else { + /* + * Re-enable automatic recomputing only if not already + * enabled. + */ + recompute_msgmni(current->nsproxy->ipc_ns); + cond_register_ipcns_notifier(current->nsproxy->ipc_ns); + } +} + #ifdef CONFIG_PROC_FS static int proc_ipc_dointvec(ctl_table *table, int write, struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos) @@ -38,17 +61,17 @@ static int proc_ipc_dointvec(ctl_table *table, int write, struct file *filp, static int proc_ipc_callback_dointvec(ctl_table *table, int write, struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos) { + struct ctl_table ipc_table; size_t lenp_bef = *lenp; int rc; - rc = proc_ipc_dointvec(table, write, filp, buffer, lenp, ppos); + memcpy(&ipc_table, table, sizeof(ipc_table)); + ipc_table.data = get_ipc(table); + + rc = proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos); if (write && !rc && lenp_bef == *lenp) - /* - * Tunable has successfully been changed from userland: - * disable its automatic recomputing. - */ - unregister_ipcns_notifier(current->nsproxy->ipc_ns); + tunable_set_callback(*((int *)(ipc_table.data))); return rc; } @@ -119,12 +142,14 @@ static int sysctl_ipc_registered_data(ctl_table *table, int __user *name, rc = sysctl_ipc_data(table, name, nlen, oldval, oldlenp, newval, newlen); - if (newval && newlen && rc > 0) + if (newval && newlen && rc > 0) { /* - * Tunable has successfully been changed from userland: - * disable its automatic recomputing. + * Tunable has successfully been changed from userland */ - unregister_ipcns_notifier(current->nsproxy->ipc_ns); + int *data = get_ipc(table); + + tunable_set_callback(*data); + } return rc; } diff --git a/ipc/ipcns_notifier.c b/ipc/ipcns_notifier.c index c797460..70ff091 100644 --- a/ipc/ipcns_notifier.c +++ b/ipc/ipcns_notifier.c @@ -61,6 +61,15 @@ int register_ipcns_notifier(struct ipc_namespace *ns) return blocking_notifier_chain_register(&ipcns_chain, &ns->ipcns_nb); } +int cond_register_ipcns_notifier(struct ipc_namespace *ns) +{ + memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb)); + ns->ipcns_nb.notifier_call = ipcns_callback; + ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI; + return blocking_notifier_chain_cond_register(&ipcns_chain, + &ns->ipcns_nb); +} + int unregister_ipcns_notifier(struct ipc_namespace *ns) { return blocking_notifier_chain_unregister(&ipcns_chain, diff --git a/kernel/notifier.c b/kernel/notifier.c index 643360d..823be115 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -31,6 +31,21 @@ static int notifier_chain_register(struct notifier_block **nl, return 0; } +static int notifier_chain_cond_register(struct notifier_block **nl, + struct notifier_block *n) +{ + while ((*nl) != NULL) { + if ((*nl) == n) + return 0; + if (n->priority > (*nl)->priority) + break; + nl = &((*nl)->next); + } + n->next = *nl; + rcu_assign_pointer(*nl, n); + return 0; +} + static int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n) { @@ -205,6 +220,29 @@ int blocking_notifier_chain_register(struct blocking_notifier_head *nh, EXPORT_SYMBOL_GPL(blocking_notifier_chain_register); /** + * blocking_notifier_chain_cond_register - Cond add notifier to a blocking notifier chain + * @nh: Pointer to head of the blocking notifier chain + * @n: New entry in notifier chain + * + * Adds a notifier to a blocking notifier chain, only if not already + * present in the chain. + * Must be called in process context. + * + * Currently always returns zero. + */ +int blocking_notifier_chain_cond_register(struct blocking_notifier_head *nh, + struct notifier_block *n) +{ + int ret; + + down_write(&nh->rwsem); + ret = notifier_chain_cond_register(&nh->head, n); + up_write(&nh->rwsem); + return ret; +} +EXPORT_SYMBOL_GPL(blocking_notifier_chain_cond_register); + +/** * blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain * @nh: Pointer to head of the blocking notifier chain * @n: Entry to remove from notifier chain |
