[Devel] Re: [PATCH 0/3] Sysctl shadow management
Pavel Emelyanov
xemul at openvz.org
Tue Nov 20 07:36:22 PST 2007
Eric W. Biederman wrote:
> To be very very very clear.
>
> This is the way I think we should do the core sysctl infrastructure.
>
> On top of the register_sysctl_table patch, getting all of the
> infrastructure in at once.
>
> With a list of lists so we don't kill ourselves when we try to
> implement sysctls that are per network devices.
Hm... My patch looks to do very very same thing, but in
a bit simpler manner. Except for the absence of the
sysctl paths, but they are just cleanups. I think I can
port them on top of my shadows :) Thanks
> I'm not yet finished testing and reviewing the code yet but I
> think this is pretty close.
Thanks,
Pavel
>>From 7a0ab8b4d471fb1f2721150a5b1737a6e407b7b8 Mon Sep 17 00:00:00 2001
> From: Eric W. Biederman <ebiederm at xmission.com>
> Date: Tue, 20 Nov 2007 07:51:50 -0700
> 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 lists. 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.
>
> __reegister_sysctl_paths is added to add a new sysctl table on
> a non-default sysctl list.
>
> Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
> ---
> include/linux/sysctl.h | 16 ++++++++-
> kernel/sysctl.c | 92 +++++++++++++++++++++++++++++++++++++++++-------
> kernel/sysctl_check.c | 25 +++++++------
> 3 files changed, 108 insertions(+), 25 deletions(-)
>
> diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> index 8b2e9e0..eeea2bb 100644
> --- a/include/linux/sysctl.h
> +++ b/include/linux/sysctl.h
> @@ -951,7 +951,9 @@ 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);
>
> @@ -1055,6 +1057,12 @@ struct ctl_table
> void *extra2;
> };
>
> +struct ctl_table_root {
> + struct list_head list;
> + struct ctl_table_header *ctl_header;
> + struct ctl_table_header *(*lookup)(struct nsproxy *namespaces);
> +};
> +
> /* struct ctl_table_header is used to maintain dynamic lists of
> struct ctl_table trees. */
> struct ctl_table_header
> @@ -1064,6 +1072,7 @@ 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 */
> @@ -1073,12 +1082,17 @@ 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 ef023b5..d5e77ec 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -156,8 +156,16 @@ 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(root_table_header.ctl_entry),
> + .root = &sysctl_table_root,
> +};
> +static struct ctl_table_root sysctl_table_root = {
> + .list = LIST_HEAD_INIT(sysctl_table_root.list),
> + .ctl_header = &root_table_header,
> +};
>
> static struct ctl_table kern_table[];
> static struct ctl_table vm_table[];
> @@ -1300,10 +1308,13 @@ 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)
> +struct ctl_table_header *__sysctl_head_next(struct nsproxy *namespaces,
> + struct ctl_table_header *prev)
> {
> - struct ctl_table_header *head;
> + struct ctl_table_root *root;
> + struct ctl_table_header *head, *first;
> struct list_head *tmp;
> +
> spin_lock(&sysctl_lock);
> if (prev) {
> tmp = &prev->ctl_entry;
> @@ -1320,13 +1331,42 @@ struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev)
> return head;
> next:
> tmp = tmp->next;
> - if (tmp == &root_table_header.ctl_entry)
> - break;
> + head = list_entry(tmp, struct ctl_table_header, ctl_entry);
> + root = head->root;
> + first = root->ctl_header;
> + if (root->lookup)
> + first = root->lookup(namespaces);
> +
> + if (head == first) {
> + next_root:
> + root = list_entry(root->list.next,
> + struct ctl_table_root, list);
> + if (root == &sysctl_table_root)
> + break;
> + first = root->ctl_header;
> + if (root->lookup)
> + first = root->lookup(namespaces);
> + if (!first)
> + goto next_root;
> + tmp = &first->ctl_entry;
> + }
> }
> 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(&sysctl_table_root.list, &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)
> @@ -1483,14 +1523,16 @@ 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
> *
> @@ -1558,10 +1600,12 @@ 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 ctl_table_header *header;
> + struct ctl_table_header *header, *first;
> struct ctl_table *new, **prevp;
> unsigned int n, npath;
>
> @@ -1603,19 +1647,40 @@ 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);
> + first = root->ctl_header;
> + if (root->lookup)
> + first = root->lookup(namespaces);
> + list_add_tail(&header->ctl_entry, &first->ctl_entry);
> 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
> *
> @@ -1648,6 +1713,7 @@ void unregister_sysctl_table(struct ctl_table_header * header)
> kfree(header);
> }
>
> +
> #else /* !CONFIG_SYSCTL */
> struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
> {
> diff --git a/kernel/sysctl_check.c b/kernel/sysctl_check.c
> index 5a2f2b2..9761561 100644
> --- a/kernel/sysctl_check.c
> +++ b/kernel/sysctl_check.c
> @@ -1383,7 +1383,8 @@ 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;
> @@ -1391,8 +1392,8 @@ 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:
> @@ -1437,13 +1438,14 @@ 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) ||
> @@ -1468,11 +1470,12 @@ 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");
> }
> @@ -1496,7 +1499,7 @@ 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++) {
> @@ -1526,7 +1529,7 @@ 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) ||
> @@ -1575,7 +1578,7 @@ 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) {
> @@ -1583,7 +1586,7 @@ 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;
> }
_______________________________________________
Containers mailing list
Containers at lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/containers
More information about the Devel
mailing list