+ proc-clean-up-proc-pid-environ-handling.patch added to -mm tree

+ proc-clean-up-proc-pid-environ-handling.patch added to -mm tree

[akpm]

The patch titled
     Subject: proc: clean up /proc/<pid>/environ handling
has been added to the -mm tree.  Its filename is
     proc-clean-up-proc-pid-environ-handling.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/SubmitChecklist when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Cong Wang <xiyou.wangcong@gmail.com>
Subject: proc: clean up /proc/<pid>/environ handling

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: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/proc/base.c |   55 +++++++++++++++++++++++++++++------------------
 1 file changed, 35 insertions(+), 20 deletions(-)

diff -puN fs/proc/base.c~proc-clean-up-proc-pid-environ-handling fs/proc/base.c
--- a/fs/proc/base.c~proc-clean-up-proc-pid-environ-handling
+++ a/fs/proc/base.c
@@ -835,28 +835,38 @@ static const struct file_operations proc
 	.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 (!mm)
+		return -ENOENT;
+	if (IS_ERR(mm))
+		return PTR_ERR(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;
-
-	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;
 	while (count > 0) {
@@ -870,7 +880,7 @@ static ssize_t environ_read(struct file 
 		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) {
@@ -890,18 +900,23 @@ static ssize_t environ_read(struct file 
 	}
 	*ppos = src;
 
-	mmput(mm);
-out_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;
+
+	mmput(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,
_
Subject: Subject: proc: clean up /proc/<pid>/environ handling

Patches currently in -mm which might be from xiyou.wangcong@gmail.com are

origin.patch
linux-next.patch
lkdtm-avoid-calling-lkdtm_do_action-with-spin-lock-held.patch
x86-mm-fix-the-size-calculation-of-mapping-tables.patch
kcore-make-get_sparsemem_vmemmap_info-static.patch
proc-clean-up-proc-pid-environ-handling.patch

Re: + proc-clean-up-proc-pid-environ-handling.patch added to -mm tree

[Oleg Nesterov]

> From: Cong Wang <xiyou.wangcong@gmail.com>
> Subject: proc: clean up /proc/<pid>/environ handling
>
> Similar to e268337dfe2 ("proc: clean up and fix /proc/<pid>/mem
> handling"),

and has the same problem,

> move the check of permission to open(), this will simplify
> read() code.

but allows to kill the system trivially.

Please look at 6d08f2c7139790c268820a2e590795cb8333181a
"proc: make sure mem_open() doesn't pin the target's memory"

Oleg.

Re: + proc-clean-up-proc-pid-environ-handling.patch added to -mm tree

[Cong Wang]

On 02/08/2012 11:15 PM, Oleg Nesterov wrote:
>> From: Cong Wang<xiyou.wangcong@gmail.com>
>> Subject: proc: clean up /proc/<pid>/environ handling
>>
>> Similar to e268337dfe2 ("proc: clean up and fix /proc/<pid>/mem
>> handling"),
>
> and has the same problem,
>
>> move the check of permission to open(), this will simplify
>> read() code.
>
> but allows to kill the system trivially.
>
> Please look at 6d08f2c7139790c268820a2e590795cb8333181a
> "proc: make sure mem_open() doesn't pin the target's memory"
>

Thanks, I wasn't aware of that commit. I will send an updated patch soon.

+ proc-clean-up-proc-pid-environ-handling.patch added to -mm tree

[akpm]

The patch titled
     Subject: proc: clean up /proc/<pid>/environ handling
has been added to the -mm tree.  Its filename is
     proc-clean-up-proc-pid-environ-handling.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/SubmitChecklist when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Cong Wang <xiyou.wangcong@gmail.com>
Subject: proc: clean up /proc/<pid>/environ handling

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: Cong 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: Andrew Morton <akpm@linux-foundation.org>
---

 fs/proc/base.c |   45 ++++++++++++++++++++++++---------------------
 1 file changed, 24 insertions(+), 21 deletions(-)

diff -puN fs/proc/base.c~proc-clean-up-proc-pid-environ-handling fs/proc/base.c
--- a/fs/proc/base.c~proc-clean-up-proc-pid-environ-handling
+++ a/fs/proc/base.c
@@ -677,7 +677,7 @@ static const struct file_operations proc
 	.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;
@@ -685,7 +685,7 @@ static int mem_open(struct inode* inode,
 	if (!task)
 		return -ESRCH;
 
-	mm = mm_access(task, PTRACE_MODE_ATTACH);
+	mm = mm_access(task, mode);
 	put_task_struct(task);
 
 	if (IS_ERR(mm))
@@ -705,6 +705,11 @@ static int mem_open(struct inode* inode,
 	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)
 {
@@ -801,30 +806,29 @@ static const struct file_operations proc
 	.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;
 
@@ -836,7 +840,7 @@ static ssize_t environ_read(struct file 
 		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 +859,18 @@ static ssize_t environ_read(struct file 
 		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,
_
Subject: Subject: proc: clean up /proc/<pid>/environ handling

Patches currently in -mm which might be from xiyou.wangcong@gmail.com are

linux-next.patch
cris-select-generic_atomic64.patch
proc-clean-up-proc-pid-environ-handling.patch
proc-unify-ptrace_may_access-locking-code.patch
proc-remove-mm_for_maps.patch
proc-use-mm_access-instead-of-ptrace_may_access.patch
proc-use-task_access_lock-instead-of-ptrace_may_access.patch
proc-use-is_err_or_null.patch