Re: [PATCH v8 10/13] module: Move procfs support into a separate file

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 22/02/2022 à 15:13, Aaron Tomlin a écrit :
> No functional change.
> 
> This patch migrates code that allows one to generate a
> list of loaded/or linked modules via /proc when procfs
> support is enabled into kernel/module/procfs.c.
> 
> Signed-off-by: Aaron Tomlin <atomlin@redhat.com>

Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>

> ---
>   kernel/module/Makefile   |   1 +
>   kernel/module/internal.h |   1 +
>   kernel/module/main.c     | 131 +-----------------------------------
>   kernel/module/procfs.c   | 142 +++++++++++++++++++++++++++++++++++++++
>   4 files changed, 145 insertions(+), 130 deletions(-)
>   create mode 100644 kernel/module/procfs.c
> 
> diff --git a/kernel/module/Makefile b/kernel/module/Makefile
> index 9901bed3ab5b..94296c98a67f 100644
> --- a/kernel/module/Makefile
> +++ b/kernel/module/Makefile
> @@ -15,3 +15,4 @@ obj-$(CONFIG_MODULES_TREE_LOOKUP) += tree_lookup.o
>   obj-$(CONFIG_STRICT_MODULE_RWX) += strict_rwx.o
>   obj-$(CONFIG_DEBUG_KMEMLEAK) += debug_kmemleak.o
>   obj-$(CONFIG_KALLSYMS) += kallsyms.o
> +obj-$(CONFIG_PROC_FS) += procfs.o
> diff --git a/kernel/module/internal.h b/kernel/module/internal.h
> index 44ca05b9eb8f..6af40c2d145f 100644
> --- a/kernel/module/internal.h
> +++ b/kernel/module/internal.h
> @@ -72,6 +72,7 @@ struct module *find_module_all(const char *name, size_t len, bool even_unformed)
>   int cmp_name(const void *name, const void *sym);
>   long module_get_offset(struct module *mod, unsigned int *size, Elf_Shdr *sechdr,
>   		       unsigned int section);
> +char *module_flags(struct module *mod, char *buf);
>   
>   static inline unsigned long kernel_symbol_value(const struct kernel_symbol *sym)
>   {
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index 952079987ea4..44b6fd1acc44 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -22,7 +22,6 @@
>   #include <linux/slab.h>
>   #include <linux/vmalloc.h>
>   #include <linux/elf.h>
> -#include <linux/proc_fs.h>
>   #include <linux/seq_file.h>
>   #include <linux/syscalls.h>
>   #include <linux/fcntl.h>
> @@ -805,31 +804,6 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
>   	return ret;
>   }
>   
> -static inline void print_unload_info(struct seq_file *m, struct module *mod)
> -{
> -	struct module_use *use;
> -	int printed_something = 0;
> -
> -	seq_printf(m, " %i ", module_refcount(mod));
> -
> -	/*
> -	 * Always include a trailing , so userspace can differentiate
> -	 * between this and the old multi-field proc format.
> -	 */
> -	list_for_each_entry(use, &mod->source_list, source_list) {
> -		printed_something = 1;
> -		seq_printf(m, "%s,", use->source->name);
> -	}
> -
> -	if (mod->init != NULL && mod->exit == NULL) {
> -		printed_something = 1;
> -		seq_puts(m, "[permanent],");
> -	}
> -
> -	if (!printed_something)
> -		seq_puts(m, "-");
> -}
> -
>   void __symbol_put(const char *symbol)
>   {
>   	struct find_symbol_arg fsa = {
> @@ -919,12 +893,6 @@ void module_put(struct module *module)
>   EXPORT_SYMBOL(module_put);
>   
>   #else /* !CONFIG_MODULE_UNLOAD */
> -static inline void print_unload_info(struct seq_file *m, struct module *mod)
> -{
> -	/* We don't know the usage count, or what modules are using. */
> -	seq_puts(m, " - -");
> -}
> -
>   static inline void module_unload_free(struct module *mod)
>   {
>   }
> @@ -3596,7 +3564,7 @@ static void cfi_cleanup(struct module *mod)
>   }
>   
>   /* Keep in sync with MODULE_FLAGS_BUF_SIZE !!! */
> -static char *module_flags(struct module *mod, char *buf)
> +char *module_flags(struct module *mod, char *buf)
>   {
>   	int bx = 0;
>   
> @@ -3619,103 +3587,6 @@ static char *module_flags(struct module *mod, char *buf)
>   	return buf;
>   }
>   
> -#ifdef CONFIG_PROC_FS
> -/* Called by the /proc file system to return a list of modules. */
> -static void *m_start(struct seq_file *m, loff_t *pos)
> -{
> -	mutex_lock(&module_mutex);
> -	return seq_list_start(&modules, *pos);
> -}
> -
> -static void *m_next(struct seq_file *m, void *p, loff_t *pos)
> -{
> -	return seq_list_next(p, &modules, pos);
> -}
> -
> -static void m_stop(struct seq_file *m, void *p)
> -{
> -	mutex_unlock(&module_mutex);
> -}
> -
> -static int m_show(struct seq_file *m, void *p)
> -{
> -	struct module *mod = list_entry(p, struct module, list);
> -	char buf[MODULE_FLAGS_BUF_SIZE];
> -	void *value;
> -
> -	/* We always ignore unformed modules. */
> -	if (mod->state == MODULE_STATE_UNFORMED)
> -		return 0;
> -
> -	seq_printf(m, "%s %u",
> -		   mod->name, mod->init_layout.size + mod->core_layout.size);
> -	print_unload_info(m, mod);
> -
> -	/* Informative for users. */
> -	seq_printf(m, " %s",
> -		   mod->state == MODULE_STATE_GOING ? "Unloading" :
> -		   mod->state == MODULE_STATE_COMING ? "Loading" :
> -		   "Live");
> -	/* Used by oprofile and other similar tools. */
> -	value = m->private ? NULL : mod->core_layout.base;
> -	seq_printf(m, " 0x%px", value);
> -
> -	/* Taints info */
> -	if (mod->taints)
> -		seq_printf(m, " %s", module_flags(mod, buf));
> -
> -	seq_puts(m, "\n");
> -	return 0;
> -}
> -
> -/*
> - * Format: modulename size refcount deps address
> - *
> - * Where refcount is a number or -, and deps is a comma-separated list
> - * of depends or -.
> - */
> -static const struct seq_operations modules_op = {
> -	.start	= m_start,
> -	.next	= m_next,
> -	.stop	= m_stop,
> -	.show	= m_show
> -};
> -
> -/*
> - * This also sets the "private" pointer to non-NULL if the
> - * kernel pointers should be hidden (so you can just test
> - * "m->private" to see if you should keep the values private).
> - *
> - * We use the same logic as for /proc/kallsyms.
> - */
> -static int modules_open(struct inode *inode, struct file *file)
> -{
> -	int err = seq_open(file, &modules_op);
> -
> -	if (!err) {
> -		struct seq_file *m = file->private_data;
> -		m->private = kallsyms_show_value(file->f_cred) ? NULL : (void *)8ul;
> -	}
> -
> -	return err;
> -}
> -
> -static const struct proc_ops modules_proc_ops = {
> -	.proc_flags	= PROC_ENTRY_PERMANENT,
> -	.proc_open	= modules_open,
> -	.proc_read	= seq_read,
> -	.proc_lseek	= seq_lseek,
> -	.proc_release	= seq_release,
> -};
> -
> -static int __init proc_modules_init(void)
> -{
> -	proc_create("modules", 0, NULL, &modules_proc_ops);
> -	return 0;
> -}
> -module_init(proc_modules_init);
> -#endif
> -
>   /* Given an address, look for it in the module exception tables. */
>   const struct exception_table_entry *search_module_extables(unsigned long addr)
>   {
> diff --git a/kernel/module/procfs.c b/kernel/module/procfs.c
> new file mode 100644
> index 000000000000..2717e130788e
> --- /dev/null
> +++ b/kernel/module/procfs.c
> @@ -0,0 +1,142 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Module proc support
> + *
> + * Copyright (C) 2008 Alexey Dobriyan
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kallsyms.h>
> +#include <linux/mutex.h>
> +#include <linux/seq_file.h>
> +#include <linux/proc_fs.h>
> +#include "internal.h"
> +
> +#ifdef CONFIG_MODULE_UNLOAD
> +static inline void print_unload_info(struct seq_file *m, struct module *mod)
> +{
> +	struct module_use *use;
> +	int printed_something = 0;
> +
> +	seq_printf(m, " %i ", module_refcount(mod));
> +
> +	/*
> +	 * Always include a trailing , so userspace can differentiate
> +	 * between this and the old multi-field proc format.
> +	 */
> +	list_for_each_entry(use, &mod->source_list, source_list) {
> +		printed_something = 1;
> +		seq_printf(m, "%s,", use->source->name);
> +	}
> +
> +	if (mod->init && !mod->exit) {
> +		printed_something = 1;
> +		seq_puts(m, "[permanent],");
> +	}
> +
> +	if (!printed_something)
> +		seq_puts(m, "-");
> +}
> +#else /* !CONFIG_MODULE_UNLOAD */
> +static inline void print_unload_info(struct seq_file *m, struct module *mod)
> +{
> +	/* We don't know the usage count, or what modules are using. */
> +	seq_puts(m, " - -");
> +}
> +#endif /* CONFIG_MODULE_UNLOAD */
> +
> +/* Called by the /proc file system to return a list of modules. */
> +static void *m_start(struct seq_file *m, loff_t *pos)
> +{
> +	mutex_lock(&module_mutex);
> +	return seq_list_start(&modules, *pos);
> +}
> +
> +static void *m_next(struct seq_file *m, void *p, loff_t *pos)
> +{
> +	return seq_list_next(p, &modules, pos);
> +}
> +
> +static void m_stop(struct seq_file *m, void *p)
> +{
> +	mutex_unlock(&module_mutex);
> +}
> +
> +static int m_show(struct seq_file *m, void *p)
> +{
> +	struct module *mod = list_entry(p, struct module, list);
> +	char buf[MODULE_FLAGS_BUF_SIZE];
> +	void *value;
> +
> +	/* We always ignore unformed modules. */
> +	if (mod->state == MODULE_STATE_UNFORMED)
> +		return 0;
> +
> +	seq_printf(m, "%s %u",
> +		   mod->name, mod->init_layout.size + mod->core_layout.size);
> +	print_unload_info(m, mod);
> +
> +	/* Informative for users. */
> +	seq_printf(m, " %s",
> +		   mod->state == MODULE_STATE_GOING ? "Unloading" :
> +		   mod->state == MODULE_STATE_COMING ? "Loading" :
> +		   "Live");
> +	/* Used by oprofile and other similar tools. */
> +	value = m->private ? NULL : mod->core_layout.base;
> +	seq_printf(m, " 0x%px", value);
> +
> +	/* Taints info */
> +	if (mod->taints)
> +		seq_printf(m, " %s", module_flags(mod, buf));
> +
> +	seq_puts(m, "\n");
> +	return 0;
> +}
> +
> +/*
> + * Format: modulename size refcount deps address
> + *
> + * Where refcount is a number or -, and deps is a comma-separated list
> + * of depends or -.
> + */
> +static const struct seq_operations modules_op = {
> +	.start	= m_start,
> +	.next	= m_next,
> +	.stop	= m_stop,
> +	.show	= m_show
> +};
> +
> +/*
> + * This also sets the "private" pointer to non-NULL if the
> + * kernel pointers should be hidden (so you can just test
> + * "m->private" to see if you should keep the values private).
> + *
> + * We use the same logic as for /proc/kallsyms.
> + */
> +static int modules_open(struct inode *inode, struct file *file)
> +{
> +	int err = seq_open(file, &modules_op);
> +
> +	if (!err) {
> +		struct seq_file *m = file->private_data;
> +
> +		m->private = kallsyms_show_value(file->f_cred) ? NULL : (void *)8ul;
> +	}
> +
> +	return err;
> +}
> +
> +static const struct proc_ops modules_proc_ops = {
> +	.proc_flags	= PROC_ENTRY_PERMANENT,
> +	.proc_open	= modules_open,
> +	.proc_read	= seq_read,
> +	.proc_lseek	= seq_lseek,
> +	.proc_release	= seq_release,
> +};
> +
> +static int __init proc_modules_init(void)
> +{
> +	proc_create("modules", 0, NULL, &modules_proc_ops);
> +	return 0;
> +}
> +module_init(proc_modules_init);