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sysctl: Add a size arg to __register_sysctl_table
We make these changes in order to prepare __register_sysctl_table and its callers for when we remove the sentinel element (empty element at the end of ctl_table arrays). We don't actually remove any sentinels in this commit, but we *do* make sure to use ARRAY_SIZE so the table_size is available when the removal occurs. We add a table_size argument to __register_sysctl_table and adjust callers, all of which pass ctl_table pointers and need an explicit call to ARRAY_SIZE. We implement a size calculation in register_net_sysctl in order to forward the size of the array pointer received from the network register calls. The new table_size argument does not yet have any effect in the init_header call which is still dependent on the sentinel's presence. table_size *does* however drive the `kzalloc` allocation in __register_sysctl_table with no adverse effects as the allocated memory is either one element greater than the calculated ctl_table array (for the calls in ipc_sysctl.c, mq_sysctl.c and ucount.c) or the exact size of the calculated ctl_table array (for the call from sysctl_net.c and register_sysctl). This approach will allows us to "just" remove the sentinel without further changes to __register_sysctl_table as table_size will represent the exact size for all the callers at that point. Signed-off-by: Joel Granados <j.granados@samsung.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
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@ -1312,6 +1312,7 @@ static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path)
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* should not be free'd after registration. So it should not be
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* used on stack. It can either be a global or dynamically allocated
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* by the caller and free'd later after sysctl unregistration.
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* @table_size : The number of elements in table
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*
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* Register a sysctl table hierarchy. @table should be a filled in ctl_table
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* array. A completely 0 filled entry terminates the table.
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@ -1354,27 +1355,20 @@ static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path)
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*/
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struct ctl_table_header *__register_sysctl_table(
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struct ctl_table_set *set,
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const char *path, struct ctl_table *table)
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const char *path, struct ctl_table *table, size_t table_size)
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{
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struct ctl_table_root *root = set->dir.header.root;
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struct ctl_table_header *header;
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struct ctl_table_header h_tmp;
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struct ctl_dir *dir;
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struct ctl_table *entry;
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struct ctl_node *node;
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int nr_entries = 0;
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h_tmp.ctl_table = table;
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list_for_each_table_entry(entry, (&h_tmp))
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nr_entries++;
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header = kzalloc(sizeof(struct ctl_table_header) +
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sizeof(struct ctl_node)*nr_entries, GFP_KERNEL_ACCOUNT);
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sizeof(struct ctl_node)*table_size, GFP_KERNEL_ACCOUNT);
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if (!header)
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return NULL;
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node = (struct ctl_node *)(header + 1);
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init_header(header, root, set, node, table, nr_entries);
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init_header(header, root, set, node, table, table_size);
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if (sysctl_check_table(path, header))
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goto fail;
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@ -1423,8 +1417,15 @@ fail:
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*/
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struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
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{
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int count = 0;
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struct ctl_table *entry;
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struct ctl_table_header t_hdr;
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t_hdr.ctl_table = table;
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list_for_each_table_entry(entry, (&t_hdr))
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count++;
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return __register_sysctl_table(&sysctl_table_root.default_set,
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path, table);
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path, table, count);
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}
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EXPORT_SYMBOL(register_sysctl);
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@ -226,7 +226,7 @@ extern void retire_sysctl_set(struct ctl_table_set *set);
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struct ctl_table_header *__register_sysctl_table(
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struct ctl_table_set *set,
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const char *path, struct ctl_table *table);
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const char *path, struct ctl_table *table, size_t table_size);
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struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
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void unregister_sysctl_table(struct ctl_table_header * table);
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@ -259,7 +259,9 @@ bool setup_ipc_sysctls(struct ipc_namespace *ns)
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tbl[i].data = NULL;
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}
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ns->ipc_sysctls = __register_sysctl_table(&ns->ipc_set, "kernel", tbl);
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ns->ipc_sysctls = __register_sysctl_table(&ns->ipc_set,
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"kernel", tbl,
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ARRAY_SIZE(ipc_sysctls));
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}
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if (!ns->ipc_sysctls) {
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kfree(tbl);
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@ -109,7 +109,9 @@ bool setup_mq_sysctls(struct ipc_namespace *ns)
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tbl[i].data = NULL;
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}
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ns->mq_sysctls = __register_sysctl_table(&ns->mq_set, "fs/mqueue", tbl);
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ns->mq_sysctls = __register_sysctl_table(&ns->mq_set,
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"fs/mqueue", tbl,
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ARRAY_SIZE(mq_sysctls));
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}
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if (!ns->mq_sysctls) {
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kfree(tbl);
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@ -104,7 +104,8 @@ bool setup_userns_sysctls(struct user_namespace *ns)
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for (i = 0; i < UCOUNT_COUNTS; i++) {
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tbl[i].data = &ns->ucount_max[i];
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}
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ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl);
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ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl,
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ARRAY_SIZE(user_table));
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}
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if (!ns->sysctls) {
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kfree(tbl);
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@ -163,10 +163,16 @@ static void ensure_safe_net_sysctl(struct net *net, const char *path,
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struct ctl_table_header *register_net_sysctl(struct net *net,
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const char *path, struct ctl_table *table)
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{
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int count = 0;
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struct ctl_table *entry;
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if (!net_eq(net, &init_net))
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ensure_safe_net_sysctl(net, path, table);
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return __register_sysctl_table(&net->sysctls, path, table);
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for (entry = table; entry->procname; entry++)
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count++;
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return __register_sysctl_table(&net->sysctls, path, table, count);
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}
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EXPORT_SYMBOL_GPL(register_net_sysctl);
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