[PATCH] fs/proc: Optimize arrays defined by struct ctl_path

From: Meng Tang <hidden>
Date: 2022-02-23 09:49:01
Also in: linux-fscrypt, linux-fsdevel, lkml
Subsystem: apparmor security module, c-sky architecture, filesystems (vfs and infrastructure), fsverity: read-only file-based authenticity protection, loadpin security module, namespaces:, proc filesystem, proc sysctl, secure computing, security subsystem, the rest, yama security module · Maintainers: John Johansen, John Johansen, Georgia Garcia, Guo Ren, Alexander Viro, Christian Brauner, Eric Biggers, Theodore Y. Ts'o, Kees Cook, Christian Brauner, Joel Granados, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds

Previously, arrays defined by struct ctl_path is terminated
with an empty one. For example, when we actually only register
one ctl_path, we've gone from 8 bytes to 16 bytes.

So, I use ARRAY_SIZE() as a boundary condition to optimize it.

Signed-off-by: Meng Tang <redacted>
---
 arch/csky/abiv1/alignment.c |  8 ++++----
 arch/nds32/mm/alignment.c   |  8 ++++----
 fs/proc/proc_sysctl.c       | 12 +++++++-----
 fs/verity/signature.c       |  7 ++++---
 include/linux/sysctl.h      |  6 +++---
 kernel/pid_namespace.c      |  5 +++--
 kernel/seccomp.c            |  7 ++++---
 security/apparmor/lsm.c     |  7 ++++---
 security/loadpin/loadpin.c  |  7 ++++---
 security/yama/yama_lsm.c    |  6 +++---
 10 files changed, 40 insertions(+), 33 deletions(-)

diff --git a/arch/csky/abiv1/alignment.c b/arch/csky/abiv1/alignment.c
index 2df115d0e210..f2fe6a4d2388 100644
--- a/arch/csky/abiv1/alignment.c
+++ b/arch/csky/abiv1/alignment.c

@@ -340,14 +340,14 @@ static struct ctl_table sysctl_table[2] = {
 	{}
 };
 
-static struct ctl_path sysctl_path[2] = {
-	{.procname = "csky"},
-	{}
+static struct ctl_path sysctl_path[1] = {
+	{.procname = "csky"}
 };
+#define SYSCTL_PATH_SIZE ARRAY_SIZE(sysctl_path)
 
 static int __init csky_alignment_init(void)
 {
-	register_sysctl_paths(sysctl_path, sysctl_table);
+	register_sysctl_paths(sysctl_path, sysctl_table, SYSCTL_PATH_SIZE);
 	return 0;
 }

diff --git a/arch/nds32/mm/alignment.c b/arch/nds32/mm/alignment.c
index 1eb7ded6992b..ee073f6b5822 100644
--- a/arch/nds32/mm/alignment.c
+++ b/arch/nds32/mm/alignment.c

@@ -560,17 +560,17 @@ static struct ctl_table nds32_sysctl_table[2] = {
 	{}
 };
 
-static struct ctl_path nds32_path[2] = {
-	{.procname = "nds32"},
-	{}
+static struct ctl_path nds32_path[1] = {
+	{.procname = "nds32"}
 };
+#define NDS32_PATH_SIZE ARRAY_SIZE(nds32_path)
 
 /*
  * Initialize nds32 alignment-correction interface
  */
 static int __init nds32_sysctl_init(void)
 {
-	register_sysctl_paths(nds32_path, nds32_sysctl_table);
+	register_sysctl_paths(nds32_path, nds32_sysctl_table, NDS32_PATH_SIZE);
 	return 0;
 }

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 7d9cfc730bd4..d6f6d9d5d3f8 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c

@@ -1552,20 +1552,21 @@ static int register_leaf_sysctl_tables(const char *path, char *pos,
  */
 struct ctl_table_header *__register_sysctl_paths(
 	struct ctl_table_set *set,
-	const struct ctl_path *path, struct ctl_table *table)
+	const struct ctl_path *path, struct ctl_table *table, int table_size)
 {
 	struct ctl_table *ctl_table_arg = table;
 	int nr_subheaders = count_subheaders(table);
 	struct ctl_table_header *header = NULL, **subheaders, **subheader;
 	const struct ctl_path *component;
 	char *new_path, *pos;
+	int i;
 
 	pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
 	if (!new_path)
 		return NULL;
 
 	pos[0] = '\0';
-	for (component = path; component->procname; component++) {
+	for (component = path, i = 0; component->procname && i < table_size; component++, i++) {
 		pos = append_path(new_path, pos, component->procname);
 		if (!pos)
 			goto out;

@@ -1622,10 +1623,11 @@ struct ctl_table_header *__register_sysctl_paths(
  * See __register_sysctl_paths for more details.
  */
 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
-						struct ctl_table *table)
+						struct ctl_table *table,
+						int table_size)
 {
 	return __register_sysctl_paths(&sysctl_table_root.default_set,
-					path, table);
+					path, table, table_size);
 }
 EXPORT_SYMBOL(register_sysctl_paths);

@@ -1642,7 +1644,7 @@ struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
 {
 	static const struct ctl_path null_path[] = { {} };
 
-	return register_sysctl_paths(null_path, table);
+	return register_sysctl_paths(null_path, table, ARRAY_SIZE(null_path));
 }
 EXPORT_SYMBOL(register_sysctl_table);

diff --git a/fs/verity/signature.c b/fs/verity/signature.c
index 143a530a8008..e04be57da6ab 100644
--- a/fs/verity/signature.c
+++ b/fs/verity/signature.c

@@ -92,9 +92,9 @@ static struct ctl_table_header *fsverity_sysctl_header;
 
 static const struct ctl_path fsverity_sysctl_path[] = {
 	{ .procname = "fs", },
-	{ .procname = "verity", },
-	{ }
+	{ .procname = "verity", }
 };
+#define FSVERITY_SYSCTL_PATH_SIZE ARRAY_SIZE(fsverity_sysctl_path)
 
 static struct ctl_table fsverity_sysctl_table[] = {
 	{

@@ -112,7 +112,8 @@ static struct ctl_table fsverity_sysctl_table[] = {
 static int __init fsverity_sysctl_init(void)
 {
 	fsverity_sysctl_header = register_sysctl_paths(fsverity_sysctl_path,
-						       fsverity_sysctl_table);
+						       fsverity_sysctl_table,
+						       FSVERITY_SYSCTL_PATH_SIZE);
 	if (!fsverity_sysctl_header) {
 		pr_err("sysctl registration failed!\n");
 		return -ENOMEM;

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 6353d6db69b2..781874ed9179 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h

@@ -220,11 +220,11 @@ struct ctl_table_header *__register_sysctl_table(
 	const char *path, struct ctl_table *table);
 struct ctl_table_header *__register_sysctl_paths(
 	struct ctl_table_set *set,
-	const struct ctl_path *path, struct ctl_table *table);
+	const struct ctl_path *path, struct ctl_table *table, int table_size);
 struct ctl_table_header *register_sysctl(const char *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);
+						struct ctl_table *table, int table_size);
 
 void unregister_sysctl_table(struct ctl_table_header * table);

@@ -271,7 +271,7 @@ static inline struct ctl_table_header *register_sysctl_mount_point(const char *p
 }
 
 static inline struct ctl_table_header *register_sysctl_paths(
-			const struct ctl_path *path, struct ctl_table *table)
+			const struct ctl_path *path, struct ctl_table *table, int table_size)
 {
 	return NULL;
 }

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index a46a3723bc66..18a1a3bb37a0 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c

@@ -294,7 +294,8 @@ static struct ctl_table pid_ns_ctl_table[] = {
 	},
 	{ }
 };
-static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
+static struct ctl_path kern_path[] = { { .procname = "kernel", } };
+#define KERN_PATH_SIZE ARRAY_SIZE(kern_path)
 #endif	/* CONFIG_CHECKPOINT_RESTORE */
 
 int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)

@@ -453,7 +454,7 @@ static __init int pid_namespaces_init(void)
 	pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC | SLAB_ACCOUNT);
 
 #ifdef CONFIG_CHECKPOINT_RESTORE
-	register_sysctl_paths(kern_path, pid_ns_ctl_table);
+	register_sysctl_paths(kern_path, pid_ns_ctl_table, KERN_PATH_SIZE);
 #endif
 	return 0;
 }

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index db10e73d06e0..d4759cdb0335 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c

@@ -2333,9 +2333,9 @@ static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
 
 static struct ctl_path seccomp_sysctl_path[] = {
 	{ .procname = "kernel", },
-	{ .procname = "seccomp", },
-	{ }
+	{ .procname = "seccomp", }
 };
+#define SECCOMP_SYSCTL_PATH_SIZE ARRAY_SIZE(seccomp_sysctl_path)
 
 static struct ctl_table seccomp_sysctl_table[] = {
 	{

@@ -2357,7 +2357,8 @@ static int __init seccomp_sysctl_init(void)
 {
 	struct ctl_table_header *hdr;
 
-	hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
+	hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table,
+				    SECCOMP_SYSCTL_PATH_SIZE);
 	if (!hdr)
 		pr_warn("sysctl registration failed\n");
 	else

diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 4f0eecb67dde..09a0461db6b1 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c

@@ -1729,9 +1729,9 @@ static int apparmor_dointvec(struct ctl_table *table, int write,
 }
 
 static struct ctl_path apparmor_sysctl_path[] = {
-	{ .procname = "kernel", },
-	{ }
+	{ .procname = "kernel", }
 };
+#define APPARMOR_SYSCTL_PATH_SIZE ARRAY_SIZE(apparmor_sysctl_path)
 
 static struct ctl_table apparmor_sysctl_table[] = {
 	{

@@ -1747,7 +1747,8 @@ static struct ctl_table apparmor_sysctl_table[] = {
 static int __init apparmor_init_sysctl(void)
 {
 	return register_sysctl_paths(apparmor_sysctl_path,
-				     apparmor_sysctl_table) ? 0 : -ENOMEM;
+				     apparmor_sysctl_table,
+				     APPARMOR_SYSCTL_PATH_SIZE) ? 0 : -ENOMEM;
 }
 #else
 static inline int apparmor_init_sysctl(void)

diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c
index b12f7d986b1e..45e0b8952a1d 100644
--- a/security/loadpin/loadpin.c
+++ b/security/loadpin/loadpin.c

@@ -48,9 +48,9 @@ static DEFINE_SPINLOCK(pinned_root_spinlock);
 
 static struct ctl_path loadpin_sysctl_path[] = {
 	{ .procname = "kernel", },
-	{ .procname = "loadpin", },
-	{ }
+	{ .procname = "loadpin", }
 };
+#define LOADPIN_SYSCTL_PATH_SIZE ARRAY_SIZE(loadpin_sysctl_path)
 
 static struct ctl_table loadpin_sysctl_table[] = {
 	{

@@ -91,7 +91,8 @@ static void check_pinning_enforcement(struct super_block *mnt_sb)
 
 	if (!ro) {
 		if (!register_sysctl_paths(loadpin_sysctl_path,
-					   loadpin_sysctl_table))
+					   loadpin_sysctl_table,
+					   LOADPIN_SYSCTL_PATH_SIZE))
 			pr_notice("sysctl registration failed!\n");
 		else
 			pr_info("enforcement can be disabled.\n");

diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 06e226166aab..c4472d17b46d 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c

@@ -449,9 +449,9 @@ static int max_scope = YAMA_SCOPE_NO_ATTACH;
 
 static struct ctl_path yama_sysctl_path[] = {
 	{ .procname = "kernel", },
-	{ .procname = "yama", },
-	{ }
+	{ .procname = "yama", }
 };
+#define YAMA_SYSCTL_PATH_SIZE ARRAY_SIZE(yama_sysctl_path)
 
 static struct ctl_table yama_sysctl_table[] = {
 	{

@@ -467,7 +467,7 @@ static struct ctl_table yama_sysctl_table[] = {
 };
 static void __init yama_init_sysctl(void)
 {
-	if (!register_sysctl_paths(yama_sysctl_path, yama_sysctl_table))
+	if (!register_sysctl_paths(yama_sysctl_path, yama_sysctl_table, YAMA_SYSCTL_PATH_SIZE))
 		panic("Yama: sysctl registration failed.\n");
 }
 #else

-- 
2.20.1

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