From: Cong Wang <xiyou.wangcong@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
Cong Wang <xiyou.wangcong@gmail.com>,
Oleg Nesterov <oleg@redhat.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Vasiliy Kulikov <segoon@openwall.com>,
David Rientjes <rientjes@google.com>
Subject: [Patch v2] proc: clean up /proc/<pid>/environ handling
Date: Tue, 3 Apr 2012 16:28:13 +0800 [thread overview]
Message-ID: <1333441703-8180-1-git-send-email-xiyou.wangcong@gmail.com> (raw)
In-Reply-To: <20120328153936.495f567a.akpm@linux-foundation.org>
V2: Add similar fix with 6d08f2c7139790c268820a2e590795cb8333181a
"proc: make sure mem_open() doesn't pin the target's memory",
suggested by Oleg.
Similar to e268337dfe2 ("proc: clean up and fix /proc/<pid>/mem
handling"), move the check of permission to open(), this will simplify
read() code.
Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
fs/proc/base.c | 65 +++++++++++++++++++++++++++++++++++++++----------------
1 files changed, 46 insertions(+), 19 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 1c8b280..b863ba3 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -801,30 +801,50 @@ static const struct file_operations proc_mem_operations = {
.release = mem_release,
};
+static int environ_open(struct inode *inode, struct file *file)
+{
+ struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
+ struct mm_struct *mm;
+
+ if (!task)
+ return -ESRCH;
+
+ mm = mm_for_maps(task);
+ put_task_struct(task);
+
+ if (IS_ERR(mm))
+ return PTR_ERR(mm);
+
+ if (mm) {
+ /* ensure this mm_struct can't be freed */
+ atomic_inc(&mm->mm_count);
+ /* but do not pin its memory */
+ mmput(mm);
+ }
+
+ file->private_data = mm;
+
+ return 0;
+}
+
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;
@@ -836,7 +856,7 @@ 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) {
@@ -855,19 +875,26 @@ 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 int environ_release(struct inode *inode, struct file *file)
+{
+ struct mm_struct *mm = file->private_data;
+ if (mm)
+ mmdrop(mm);
+ return 0;
+}
+
static const struct file_operations proc_environ_operations = {
+ .open = environ_open,
.read = environ_read,
.llseek = generic_file_llseek,
+ .release = environ_release,
};
static ssize_t oom_adjust_read(struct file *file, char __user *buf,
next parent reply other threads:[~2012-04-03 8:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20120328153936.495f567a.akpm@linux-foundation.org>
2012-04-03 8:28 ` Cong Wang [this message]
2012-04-03 15:02 ` [Patch v2] proc: clean up /proc/<pid>/environ handling Oleg Nesterov
2012-04-04 5:58 ` Cong Wang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1333441703-8180-1-git-send-email-xiyou.wangcong@gmail.com \
--to=xiyou.wangcong@gmail.com \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=oleg@redhat.com \
--cc=rientjes@google.com \
--cc=segoon@openwall.com \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).