From dc55e35f9e810f23dd69cfdc91a3d636023f57a2 Mon Sep 17 00:00:00 2001 From: Alexey Gladkov Date: Mon, 14 Feb 2022 19:18:14 +0100 Subject: ipc: Store mqueue sysctls in the ipc namespace Right now, the mqueue sysctls take ipc namespaces into account in a rather hacky way. This works in most cases, but does not respect the user namespace. Within the user namespace, the user cannot change the /proc/sys/fs/mqueue/* parametres. This poses a problem in the rootless containers. To solve this I changed the implementation of the mqueue sysctls just like some other sysctls. So far, the changes do not provide additional access to files. This will be done in a future patch. v3: * Don't implemenet set_permissions to keep the current behavior. v2: * Fixed compilation problem if CONFIG_POSIX_MQUEUE_SYSCTL is not specified. Reported-by: kernel test robot Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/b0ccbb2489119f1f20c737cf1930c3a9c4e4243a.1644862280.git.legion@kernel.org Signed-off-by: Eric W. Biederman --- ipc/mq_sysctl.c | 121 ++++++++++++++++++++++++++++++-------------------------- ipc/mqueue.c | 10 ++--- ipc/namespace.c | 6 +++ 3 files changed, 76 insertions(+), 61 deletions(-) (limited to 'ipc') diff --git a/ipc/mq_sysctl.c b/ipc/mq_sysctl.c index 72a92a08c848..fbf6a8b93a26 100644 --- a/ipc/mq_sysctl.c +++ b/ipc/mq_sysctl.c @@ -9,39 +9,9 @@ #include #include -#ifdef CONFIG_PROC_SYSCTL -static void *get_mq(struct ctl_table *table) -{ - char *which = table->data; - struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; - which = (which - (char *)&init_ipc_ns) + (char *)ipc_ns; - return which; -} - -static int proc_mq_dointvec(struct ctl_table *table, int write, - void *buffer, size_t *lenp, loff_t *ppos) -{ - struct ctl_table mq_table; - memcpy(&mq_table, table, sizeof(mq_table)); - mq_table.data = get_mq(table); - - return proc_dointvec(&mq_table, write, buffer, lenp, ppos); -} - -static int proc_mq_dointvec_minmax(struct ctl_table *table, int write, - void *buffer, size_t *lenp, loff_t *ppos) -{ - struct ctl_table mq_table; - memcpy(&mq_table, table, sizeof(mq_table)); - mq_table.data = get_mq(table); - - return proc_dointvec_minmax(&mq_table, write, buffer, - lenp, ppos); -} -#else -#define proc_mq_dointvec NULL -#define proc_mq_dointvec_minmax NULL -#endif +#include +#include +#include static int msg_max_limit_min = MIN_MSGMAX; static int msg_max_limit_max = HARD_MSGMAX; @@ -55,14 +25,14 @@ static struct ctl_table mq_sysctls[] = { .data = &init_ipc_ns.mq_queues_max, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_mq_dointvec, + .proc_handler = proc_dointvec, }, { .procname = "msg_max", .data = &init_ipc_ns.mq_msg_max, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_mq_dointvec_minmax, + .proc_handler = proc_dointvec_minmax, .extra1 = &msg_max_limit_min, .extra2 = &msg_max_limit_max, }, @@ -71,7 +41,7 @@ static struct ctl_table mq_sysctls[] = { .data = &init_ipc_ns.mq_msgsize_max, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_mq_dointvec_minmax, + .proc_handler = proc_dointvec_minmax, .extra1 = &msg_maxsize_limit_min, .extra2 = &msg_maxsize_limit_max, }, @@ -80,7 +50,7 @@ static struct ctl_table mq_sysctls[] = { .data = &init_ipc_ns.mq_msg_default, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_mq_dointvec_minmax, + .proc_handler = proc_dointvec_minmax, .extra1 = &msg_max_limit_min, .extra2 = &msg_max_limit_max, }, @@ -89,32 +59,73 @@ static struct ctl_table mq_sysctls[] = { .data = &init_ipc_ns.mq_msgsize_default, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_mq_dointvec_minmax, + .proc_handler = proc_dointvec_minmax, .extra1 = &msg_maxsize_limit_min, .extra2 = &msg_maxsize_limit_max, }, {} }; -static struct ctl_table mq_sysctl_dir[] = { - { - .procname = "mqueue", - .mode = 0555, - .child = mq_sysctls, - }, - {} -}; +static struct ctl_table_set *set_lookup(struct ctl_table_root *root) +{ + return ¤t->nsproxy->ipc_ns->mq_set; +} -static struct ctl_table mq_sysctl_root[] = { - { - .procname = "fs", - .mode = 0555, - .child = mq_sysctl_dir, - }, - {} +static int set_is_seen(struct ctl_table_set *set) +{ + return ¤t->nsproxy->ipc_ns->mq_set == set; +} + +static struct ctl_table_root set_root = { + .lookup = set_lookup, }; -struct ctl_table_header *mq_register_sysctl_table(void) +bool setup_mq_sysctls(struct ipc_namespace *ns) { - return register_sysctl_table(mq_sysctl_root); + struct ctl_table *tbl; + + setup_sysctl_set(&ns->mq_set, &set_root, set_is_seen); + + tbl = kmemdup(mq_sysctls, sizeof(mq_sysctls), GFP_KERNEL); + if (tbl) { + int i; + + for (i = 0; i < ARRAY_SIZE(mq_sysctls); i++) { + if (tbl[i].data == &init_ipc_ns.mq_queues_max) + tbl[i].data = &ns->mq_queues_max; + + else if (tbl[i].data == &init_ipc_ns.mq_msg_max) + tbl[i].data = &ns->mq_msg_max; + + else if (tbl[i].data == &init_ipc_ns.mq_msgsize_max) + tbl[i].data = &ns->mq_msgsize_max; + + else if (tbl[i].data == &init_ipc_ns.mq_msg_default) + tbl[i].data = &ns->mq_msg_default; + + else if (tbl[i].data == &init_ipc_ns.mq_msgsize_default) + tbl[i].data = &ns->mq_msgsize_default; + else + tbl[i].data = NULL; + } + + ns->mq_sysctls = __register_sysctl_table(&ns->mq_set, "fs/mqueue", tbl); + } + if (!ns->mq_sysctls) { + kfree(tbl); + retire_sysctl_set(&ns->mq_set); + return false; + } + + return true; +} + +void retire_mq_sysctls(struct ipc_namespace *ns) +{ + struct ctl_table *tbl; + + tbl = ns->mq_sysctls->ctl_table_arg; + unregister_sysctl_table(ns->mq_sysctls); + retire_sysctl_set(&ns->mq_set); + kfree(tbl); } diff --git a/ipc/mqueue.c b/ipc/mqueue.c index 5becca9be867..1b4a3be71636 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -163,8 +163,6 @@ static void remove_notification(struct mqueue_inode_info *info); static struct kmem_cache *mqueue_inode_cachep; -static struct ctl_table_header *mq_sysctl_table; - static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) { return container_of(inode, struct mqueue_inode_info, vfs_inode); @@ -1713,8 +1711,10 @@ static int __init init_mqueue_fs(void) if (mqueue_inode_cachep == NULL) return -ENOMEM; - /* ignore failures - they are not fatal */ - mq_sysctl_table = mq_register_sysctl_table(); + if (!setup_mq_sysctls(&init_ipc_ns)) { + pr_warn("sysctl registration failed\n"); + return -ENOMEM; + } error = register_filesystem(&mqueue_fs_type); if (error) @@ -1731,8 +1731,6 @@ static int __init init_mqueue_fs(void) out_filesystem: unregister_filesystem(&mqueue_fs_type); out_sysctl: - if (mq_sysctl_table) - unregister_sysctl_table(mq_sysctl_table); kmem_cache_destroy(mqueue_inode_cachep); return error; } diff --git a/ipc/namespace.c b/ipc/namespace.c index ae83f0f2651b..f760243ca685 100644 --- a/ipc/namespace.c +++ b/ipc/namespace.c @@ -59,6 +59,10 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns, if (err) goto fail_put; + err = -ENOMEM; + if (!setup_mq_sysctls(ns)) + goto fail_put; + sem_init_ns(ns); msg_init_ns(ns); shm_init_ns(ns); @@ -125,6 +129,8 @@ static void free_ipc_ns(struct ipc_namespace *ns) msg_exit_ns(ns); shm_exit_ns(ns); + retire_mq_sysctls(ns); + dec_ipc_namespaces(ns->ucounts); put_user_ns(ns->user_ns); ns_free_inum(&ns->ns); -- cgit v1.2.3