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Commit b409e578 authored by Cong Wang's avatar Cong Wang Committed by Linus Torvalds
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proc: clean up /proc/<pid>/environ handling 



Similar to e268337d ("proc: clean up and fix /proc/<pid>/mem
handling"), move the check of permission to open(), this will simplify
read() code.

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 168eeccb

fs/proc/base.c

+24 −21
Original line number Diff line number Diff line
@@ -679,7 +679,7 @@ static const struct file_operations proc_single_file_operations = { 
	.release	= single_release,

};



static int mem_open(struct inode* inode, struct file* file)

static int __mem_open(struct inode *inode, struct file *file, unsigned int mode)

{

	struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);

	struct mm_struct *mm;
@@ -687,7 +687,7 @@ static int mem_open(struct inode* inode, struct file* file) 
	if (!task)

		return -ESRCH;



	mm = mm_access(task, PTRACE_MODE_ATTACH);

	mm = mm_access(task, mode);

	put_task_struct(task);



	if (IS_ERR(mm))
@@ -707,6 +707,11 @@ static int mem_open(struct inode* inode, struct file* file) 
	return 0;

}



static int mem_open(struct inode *inode, struct file *file)

{

	return __mem_open(inode, file, PTRACE_MODE_ATTACH);

}



static ssize_t mem_rw(struct file *file, char __user *buf,

			size_t count, loff_t *ppos, int write)

{
@@ -803,30 +808,29 @@ static const struct file_operations proc_mem_operations = { 
	.release	= mem_release,

};



static int environ_open(struct inode *inode, struct file *file)

{

	return __mem_open(inode, file, PTRACE_MODE_READ);

}



static ssize_t environ_read(struct file *file, char __user *buf,

			size_t count, loff_t *ppos)

{

	struct task_struct *task = get_proc_task(file->f_dentry->d_inode);

	char *page;

	unsigned long src = *ppos;

	int ret = -ESRCH;

	struct mm_struct *mm;

	int ret = 0;

	struct mm_struct *mm = file->private_data;



	if (!task)

		goto out_no_task;

	if (!mm)

		return 0;



	ret = -ENOMEM;

	page = (char *)__get_free_page(GFP_TEMPORARY);

	if (!page)

		goto out;





	mm = mm_for_maps(task);

	ret = PTR_ERR(mm);

	if (!mm || IS_ERR(mm))

		goto out_free;

		return -ENOMEM;



	ret = 0;

	if (!atomic_inc_not_zero(&mm->mm_users))

		goto free;

	while (count > 0) {

		int this_len, retval, max_len;
@@ -838,7 +842,7 @@ static ssize_t environ_read(struct file *file, char __user *buf, 
		max_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;

		this_len = (this_len > max_len) ? max_len : this_len;



		retval = access_process_vm(task, (mm->env_start + src),

		retval = access_remote_vm(mm, (mm->env_start + src),

			page, this_len, 0);



		if (retval <= 0) {
@@ -857,19 +861,18 @@ static ssize_t environ_read(struct file *file, char __user *buf, 
		count -= retval;

	}

	*ppos = src;



	mmput(mm);

out_free:



free:

	free_page((unsigned long) page);

out:

	put_task_struct(task);

out_no_task:

	return ret;

}



static const struct file_operations proc_environ_operations = {

	.open		= environ_open,

	.read		= environ_read,

	.llseek		= generic_file_llseek,

	.release	= mem_release,

};



static ssize_t oom_adjust_read(struct file *file, char __user *buf,