From e51b6ba077791f2f8c876022b37419be7a2ceec3 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 30 Nov 2007 23:54:00 +1100 Subject: [PATCH] sysctl: Infrastructure for per namespace sysctls This patch implements the basic infrastructure for per namespace sysctls. A list of lists of sysctl headers is added, allowing each namespace to have it's own list of sysctl headers. Each list of sysctl headers has a lookup function to find the first sysctl header in the list, allowing the lists to have a per namespace instance. register_sysct_root is added to tell sysctl.c about additional lists of sysctl_headers. As all of the users are expected to be in kernel no unregister function is provided. sysctl_head_next is updated to walk through the list of lists. __register_sysctl_paths is added to add a new sysctl table on a non-default sysctl list. The only intrusive part of this patch is propagating the information to decided which list of sysctls to use for sysctl_check_table. Signed-off-by: Eric W. Biederman Cc: Serge Hallyn Cc: Daniel Lezcano Cc: Cedric Le Goater Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- include/linux/sysctl.h | 17 +++++++- kernel/sysctl.c | 93 +++++++++++++++++++++++++++++++++++++----- kernel/sysctl_check.c | 25 +++++++----- 3 files changed, 112 insertions(+), 23 deletions(-) diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index 77de3bfd874..89faebfe48b 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -945,7 +945,10 @@ enum /* For the /proc/sys support */ struct ctl_table; +struct nsproxy; extern struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev); +extern struct ctl_table_header *__sysctl_head_next(struct nsproxy *namespaces, + struct ctl_table_header *prev); extern void sysctl_head_finish(struct ctl_table_header *prev); extern int sysctl_perm(struct ctl_table *table, int op); @@ -1049,6 +1052,13 @@ struct ctl_table void *extra2; }; +struct ctl_table_root { + struct list_head root_list; + struct list_head header_list; + struct list_head *(*lookup)(struct ctl_table_root *root, + struct nsproxy *namespaces); +}; + /* struct ctl_table_header is used to maintain dynamic lists of struct ctl_table trees. */ struct ctl_table_header @@ -1058,6 +1068,7 @@ struct ctl_table_header int used; struct completion *unregistering; struct ctl_table *ctl_table_arg; + struct ctl_table_root *root; }; /* struct ctl_path describes where in the hierarchy a table is added */ @@ -1066,12 +1077,16 @@ struct ctl_path { int ctl_name; }; +void register_sysctl_root(struct ctl_table_root *root); +struct ctl_table_header *__register_sysctl_paths( + struct ctl_table_root *root, struct nsproxy *namespaces, + const struct ctl_path *path, struct ctl_table *table); struct ctl_table_header *register_sysctl_table(struct ctl_table * table); struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, struct ctl_table *table); void unregister_sysctl_table(struct ctl_table_header * table); -int sysctl_check_table(struct ctl_table *table); +int sysctl_check_table(struct nsproxy *namespaces, struct ctl_table *table); #else /* __KERNEL__ */ diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 89b7d95ecf5..45e76f209dc 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -157,8 +157,16 @@ static int proc_dointvec_taint(struct ctl_table *table, int write, struct file * #endif static struct ctl_table root_table[]; -static struct ctl_table_header root_table_header = - { root_table, LIST_HEAD_INIT(root_table_header.ctl_entry) }; +static struct ctl_table_root sysctl_table_root; +static struct ctl_table_header root_table_header = { + .ctl_table = root_table, + .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.header_list), + .root = &sysctl_table_root, +}; +static struct ctl_table_root sysctl_table_root = { + .root_list = LIST_HEAD_INIT(sysctl_table_root.root_list), + .header_list = LIST_HEAD_INIT(root_table_header.ctl_entry), +}; static struct ctl_table kern_table[]; static struct ctl_table vm_table[]; @@ -1371,12 +1379,27 @@ void sysctl_head_finish(struct ctl_table_header *head) spin_unlock(&sysctl_lock); } -struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev) +static struct list_head * +lookup_header_list(struct ctl_table_root *root, struct nsproxy *namespaces) { + struct list_head *header_list; + header_list = &root->header_list; + if (root->lookup) + header_list = root->lookup(root, namespaces); + return header_list; +} + +struct ctl_table_header *__sysctl_head_next(struct nsproxy *namespaces, + struct ctl_table_header *prev) +{ + struct ctl_table_root *root; + struct list_head *header_list; struct ctl_table_header *head; struct list_head *tmp; + spin_lock(&sysctl_lock); if (prev) { + head = prev; tmp = &prev->ctl_entry; unuse_table(prev); goto next; @@ -1390,14 +1413,38 @@ struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev) spin_unlock(&sysctl_lock); return head; next: + root = head->root; tmp = tmp->next; - if (tmp == &root_table_header.ctl_entry) - break; + header_list = lookup_header_list(root, namespaces); + if (tmp != header_list) + continue; + + do { + root = list_entry(root->root_list.next, + struct ctl_table_root, root_list); + if (root == &sysctl_table_root) + goto out; + header_list = lookup_header_list(root, namespaces); + } while (list_empty(header_list)); + tmp = header_list->next; } +out: spin_unlock(&sysctl_lock); return NULL; } +struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev) +{ + return __sysctl_head_next(current->nsproxy, prev); +} + +void register_sysctl_root(struct ctl_table_root *root) +{ + spin_lock(&sysctl_lock); + list_add_tail(&root->root_list, &sysctl_table_root.root_list); + spin_unlock(&sysctl_lock); +} + #ifdef CONFIG_SYSCTL_SYSCALL int do_sysctl(int __user *name, int nlen, void __user *oldval, size_t __user *oldlenp, void __user *newval, size_t newlen) @@ -1554,14 +1601,16 @@ static __init int sysctl_init(void) { int err; sysctl_set_parent(NULL, root_table); - err = sysctl_check_table(root_table); + err = sysctl_check_table(current->nsproxy, root_table); return 0; } core_initcall(sysctl_init); /** - * register_sysctl_paths - register a sysctl hierarchy + * __register_sysctl_paths - register a sysctl hierarchy + * @root: List of sysctl headers to register on + * @namespaces: Data to compute which lists of sysctl entries are visible * @path: The path to the directory the sysctl table is in. * @table: the top-level table structure * @@ -1629,9 +1678,12 @@ core_initcall(sysctl_init); * This routine returns %NULL on a failure to register, and a pointer * to the table header on success. */ -struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, - struct ctl_table *table) +struct ctl_table_header *__register_sysctl_paths( + struct ctl_table_root *root, + struct nsproxy *namespaces, + const struct ctl_path *path, struct ctl_table *table) { + struct list_head *header_list; struct ctl_table_header *header; struct ctl_table *new, **prevp; unsigned int n, npath; @@ -1674,18 +1726,37 @@ struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, INIT_LIST_HEAD(&header->ctl_entry); header->used = 0; header->unregistering = NULL; + header->root = root; sysctl_set_parent(NULL, header->ctl_table); - if (sysctl_check_table(header->ctl_table)) { + if (sysctl_check_table(namespaces, header->ctl_table)) { kfree(header); return NULL; } spin_lock(&sysctl_lock); - list_add_tail(&header->ctl_entry, &root_table_header.ctl_entry); + header_list = lookup_header_list(root, namespaces); + list_add_tail(&header->ctl_entry, header_list); spin_unlock(&sysctl_lock); return header; } +/** + * register_sysctl_table_path - register a sysctl table hierarchy + * @path: The path to the directory the sysctl table is in. + * @table: the top-level table structure + * + * Register a sysctl table hierarchy. @table should be a filled in ctl_table + * array. A completely 0 filled entry terminates the table. + * + * See __register_sysctl_paths for more details. + */ +struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, + struct ctl_table *table) +{ + return __register_sysctl_paths(&sysctl_table_root, current->nsproxy, + path, table); +} + /** * register_sysctl_table - register a sysctl table hierarchy * @table: the top-level table structure diff --git a/kernel/sysctl_check.c b/kernel/sysctl_check.c index d8a5558a47b..c3206fa5004 100644 --- a/kernel/sysctl_check.c +++ b/kernel/sysctl_check.c @@ -1342,7 +1342,8 @@ static void sysctl_repair_table(struct ctl_table *table) } } -static struct ctl_table *sysctl_check_lookup(struct ctl_table *table) +static struct ctl_table *sysctl_check_lookup(struct nsproxy *namespaces, + struct ctl_table *table) { struct ctl_table_header *head; struct ctl_table *ref, *test; @@ -1350,8 +1351,8 @@ static struct ctl_table *sysctl_check_lookup(struct ctl_table *table) depth = sysctl_depth(table); - for (head = sysctl_head_next(NULL); head; - head = sysctl_head_next(head)) { + for (head = __sysctl_head_next(namespaces, NULL); head; + head = __sysctl_head_next(namespaces, head)) { cur_depth = depth; ref = head->ctl_table; repeat: @@ -1396,13 +1397,14 @@ static void set_fail(const char **fail, struct ctl_table *table, const char *str *fail = str; } -static int sysctl_check_dir(struct ctl_table *table) +static int sysctl_check_dir(struct nsproxy *namespaces, + struct ctl_table *table) { struct ctl_table *ref; int error; error = 0; - ref = sysctl_check_lookup(table); + ref = sysctl_check_lookup(namespaces, table); if (ref) { int match = 0; if ((!table->procname && !ref->procname) || @@ -1427,11 +1429,12 @@ static int sysctl_check_dir(struct ctl_table *table) return error; } -static void sysctl_check_leaf(struct ctl_table *table, const char **fail) +static void sysctl_check_leaf(struct nsproxy *namespaces, + struct ctl_table *table, const char **fail) { struct ctl_table *ref; - ref = sysctl_check_lookup(table); + ref = sysctl_check_lookup(namespaces, table); if (ref && (ref != table)) set_fail(fail, table, "Sysctl already exists"); } @@ -1455,7 +1458,7 @@ static void sysctl_check_bin_path(struct ctl_table *table, const char **fail) } } -int sysctl_check_table(struct ctl_table *table) +int sysctl_check_table(struct nsproxy *namespaces, struct ctl_table *table) { int error = 0; for (; table->ctl_name || table->procname; table++) { @@ -1485,7 +1488,7 @@ int sysctl_check_table(struct ctl_table *table) set_fail(&fail, table, "Directory with extra1"); if (table->extra2) set_fail(&fail, table, "Directory with extra2"); - if (sysctl_check_dir(table)) + if (sysctl_check_dir(namespaces, table)) set_fail(&fail, table, "Inconsistent directory names"); } else { if ((table->strategy == sysctl_data) || @@ -1534,7 +1537,7 @@ int sysctl_check_table(struct ctl_table *table) if (!table->procname && table->proc_handler) set_fail(&fail, table, "proc_handler without procname"); #endif - sysctl_check_leaf(table, &fail); + sysctl_check_leaf(namespaces, table, &fail); } sysctl_check_bin_path(table, &fail); if (fail) { @@ -1542,7 +1545,7 @@ int sysctl_check_table(struct ctl_table *table) error = -EINVAL; } if (table->child) - error |= sysctl_check_table(table->child); + error |= sysctl_check_table(namespaces, table->child); } return error; } -- 2.41.1