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

From: Meng Tang
Date: Wed Feb 23 2022 - 04:49:09 EST

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 <tangmeng@xxxxxxxxxxxxx>
---
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