[PATCH v3 05/14] sysctl: Add a size arg to __register_sysctl_table
From: Joel Granados <hidden>
Date: 2023-08-09 10:50:43
Also in:
bridge, linux-fsdevel, linux-hams, linux-rdma, linux-s390, linux-sctp, lkml, lvs-devel, mptcp, netfilter-devel
Subsystem:
filesystems (vfs and infrastructure), networking [general], proc filesystem, proc sysctl, the rest · Maintainers:
Alexander Viro, Christian Brauner, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Kees Cook, Joel Granados, Linus Torvalds
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 <redacted> --- fs/proc/proc_sysctl.c | 23 ++++++++++++----------- include/linux/sysctl.h | 2 +- ipc/ipc_sysctl.c | 4 +++- ipc/mq_sysctl.c | 4 +++- kernel/ucount.c | 3 ++- net/sysctl_net.c | 8 +++++++- 6 files changed, 28 insertions(+), 16 deletions(-)
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index fa1438f1a355..b8dd78e344ff 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c@@ -1312,6 +1312,7 @@ static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path) * should not be free'd after registration. So it should not be * used on stack. It can either be a global or dynamically allocated * by the caller and free'd later after sysctl unregistration. + * @table_size : The number of elements in table * * Register a sysctl table hierarchy. @table should be a filled in ctl_table * array. A completely 0 filled entry terminates the table.
@@ -1354,27 +1355,20 @@ static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path) */ struct ctl_table_header *__register_sysctl_table( struct ctl_table_set *set, - const char *path, struct ctl_table *table) + const char *path, struct ctl_table *table, size_t table_size) { struct ctl_table_root *root = set->dir.header.root; struct ctl_table_header *header; - struct ctl_table_header h_tmp; struct ctl_dir *dir; - struct ctl_table *entry; struct ctl_node *node; - int nr_entries = 0; - - h_tmp.ctl_table = table; - list_for_each_table_entry(entry, (&h_tmp)) - nr_entries++; header = kzalloc(sizeof(struct ctl_table_header) + - sizeof(struct ctl_node)*nr_entries, GFP_KERNEL_ACCOUNT); + sizeof(struct ctl_node)*table_size, GFP_KERNEL_ACCOUNT); if (!header) return NULL; node = (struct ctl_node *)(header + 1); - init_header(header, root, set, node, table, nr_entries); + init_header(header, root, set, node, table, table_size); if (sysctl_check_table(path, header)) goto fail;
@@ -1423,8 +1417,15 @@ struct ctl_table_header *__register_sysctl_table( */ struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table) { + int count = 0; + struct ctl_table *entry; + struct ctl_table_header t_hdr; + + t_hdr.ctl_table = table; + list_for_each_table_entry(entry, (&t_hdr)) + count++; return __register_sysctl_table(&sysctl_table_root.default_set, - path, table); + path, table, count); } EXPORT_SYMBOL(register_sysctl);
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 33252ad58ebe..0495c858989f 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h@@ -226,7 +226,7 @@ extern void retire_sysctl_set(struct ctl_table_set *set); struct ctl_table_header *__register_sysctl_table( struct ctl_table_set *set, - const char *path, struct ctl_table *table); + const char *path, struct ctl_table *table, size_t table_size); struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table); void unregister_sysctl_table(struct ctl_table_header * table);
diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index ef313ecfb53a..8c62e443f78b 100644
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c@@ -259,7 +259,9 @@ bool setup_ipc_sysctls(struct ipc_namespace *ns) tbl[i].data = NULL; } - ns->ipc_sysctls = __register_sysctl_table(&ns->ipc_set, "kernel", tbl); + ns->ipc_sysctls = __register_sysctl_table(&ns->ipc_set, + "kernel", tbl, + ARRAY_SIZE(ipc_sysctls)); } if (!ns->ipc_sysctls) { kfree(tbl);
diff --git a/ipc/mq_sysctl.c b/ipc/mq_sysctl.c
index fbf6a8b93a26..ebb5ed81c151 100644
--- a/ipc/mq_sysctl.c
+++ b/ipc/mq_sysctl.c@@ -109,7 +109,9 @@ bool setup_mq_sysctls(struct ipc_namespace *ns) tbl[i].data = NULL; } - ns->mq_sysctls = __register_sysctl_table(&ns->mq_set, "fs/mqueue", tbl); + ns->mq_sysctls = __register_sysctl_table(&ns->mq_set, + "fs/mqueue", tbl, + ARRAY_SIZE(mq_sysctls)); } if (!ns->mq_sysctls) { kfree(tbl);
diff --git a/kernel/ucount.c b/kernel/ucount.c
index ee8e57fd6f90..2b80264bb79f 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c@@ -104,7 +104,8 @@ bool setup_userns_sysctls(struct user_namespace *ns) for (i = 0; i < UCOUNT_COUNTS; i++) { tbl[i].data = &ns->ucount_max[i]; } - ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl); + ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl, + ARRAY_SIZE(user_table)); } if (!ns->sysctls) { kfree(tbl);
diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index 4b45ed631eb8..8ee4b74bc009 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c@@ -163,10 +163,16 @@ static void ensure_safe_net_sysctl(struct net *net, const char *path, struct ctl_table_header *register_net_sysctl(struct net *net, const char *path, struct ctl_table *table) { + int count = 0; + struct ctl_table *entry; + if (!net_eq(net, &init_net)) ensure_safe_net_sysctl(net, path, table); - return __register_sysctl_table(&net->sysctls, path, table); + for (entry = table; entry->procname; entry++) + count++; + + return __register_sysctl_table(&net->sysctls, path, table, count); } EXPORT_SYMBOL_GPL(register_net_sysctl);
--
2.30.2