From b409e578d9a4ec95913e06d8fea2a33f1754ea69 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Thu, 31 May 2012 16:26:17 -0700 Subject: [PATCH] proc: clean up /proc//environ handling Similar to e268337dfe26 ("proc: clean up and fix /proc//mem handling"), move the check of permission to open(), this will simplify read() code. [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: Cong Wang Cc: Oleg Nesterov Cc: Alexey Dobriyan Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/base.c | 45 ++++++++++++++++++++++++--------------------- 1 file changed, 24 insertions(+), 21 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index d7d711876b6a..e2d234243269 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -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,