[PATCH 2/6] proc: unify ptrace_may_access locking code

[Cong Wang]

Unify mutex_lock+ptrace_may_access code and rename lock_trace()
to task_access_lock(), which better describes what it does.

Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
---
 fs/proc/base.c |   36 +++++++++++++++---------------------
 1 files changed, 15 insertions(+), 21 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index f3c4887..919d14c 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -281,19 +281,19 @@ static int proc_pid_wchan(struct task_struct *task, char *buffer)
 }
 #endif /* CONFIG_KALLSYMS */
 
-static int lock_trace(struct task_struct *task)
+static int task_access_lock(struct task_struct *task, unsigned int mode)
 {
 	int err = mutex_lock_killable(&task->signal->cred_guard_mutex);
 	if (err)
 		return err;
-	if (!ptrace_may_access(task, PTRACE_MODE_ATTACH)) {
+	if (!ptrace_may_access(task, mode)) {
 		mutex_unlock(&task->signal->cred_guard_mutex);
 		return -EPERM;
 	}
 	return 0;
 }
 
-static void unlock_trace(struct task_struct *task)
+static void task_access_unlock(struct task_struct *task)
 {
 	mutex_unlock(&task->signal->cred_guard_mutex);
 }
@@ -319,7 +319,7 @@ static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
 	trace.entries		= entries;
 	trace.skip		= 0;
 
-	err = lock_trace(task);
+	err = task_access_lock(task, PTRACE_MODE_ATTACH);
 	if (!err) {
 		save_stack_trace_tsk(task, &trace);
 
@@ -327,7 +327,7 @@ static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
 			seq_printf(m, "[<%pK>] %pS\n",
 				   (void *)entries[i], (void *)entries[i]);
 		}
-		unlock_trace(task);
+		task_access_unlock(task);
 	}
 	kfree(entries);
 
@@ -494,7 +494,7 @@ static int proc_pid_syscall(struct task_struct *task, char *buffer)
 {
 	long nr;
 	unsigned long args[6], sp, pc;
-	int res = lock_trace(task);
+	int res = task_access_lock(task, PTRACE_MODE_ATTACH);
 	if (res)
 		return res;
 
@@ -508,7 +508,7 @@ static int proc_pid_syscall(struct task_struct *task, char *buffer)
 		       nr,
 		       args[0], args[1], args[2], args[3], args[4], args[5],
 		       sp, pc);
-	unlock_trace(task);
+	task_access_unlock(task);
 	return res;
 }
 #endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
@@ -2180,7 +2180,7 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 		goto out;
 
 	result = ERR_PTR(-EACCES);
-	if (lock_trace(task))
+	if (task_access_lock(task, PTRACE_MODE_ATTACH))
 		goto out_put_task;
 
 	result = ERR_PTR(-ENOENT);
@@ -2202,7 +2202,7 @@ out_no_vma:
 	up_read(&mm->mmap_sem);
 	mmput(mm);
 out_unlock:
-	unlock_trace(task);
+	task_access_unlock(task);
 out_put_task:
 	put_task_struct(task);
 out:
@@ -2236,7 +2236,7 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
 		goto out;
 
 	ret = -EACCES;
-	if (lock_trace(task))
+	if (task_access_lock(task, PTRACE_MODE_ATTACH))
 		goto out_put_task;
 
 	ret = 0;
@@ -2336,7 +2336,7 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
 	}
 
 out_unlock:
-	unlock_trace(task);
+	task_access_unlock(task);
 out_put_task:
 	put_task_struct(task);
 out:
@@ -2897,15 +2897,10 @@ static int do_io_accounting(struct task_struct *task, char *buffer, int whole)
 	unsigned long flags;
 	int result;
 
-	result = mutex_lock_killable(&task->signal->cred_guard_mutex);
+	result = task_access_lock(task, PTRACE_MODE_READ);
 	if (result)
 		return result;
 
-	if (!ptrace_may_access(task, PTRACE_MODE_READ)) {
-		result = -EACCES;
-		goto out_unlock;
-	}
-
 	if (whole && lock_task_sighand(task, &flags)) {
 		struct task_struct *t = task;
 
@@ -2930,8 +2925,7 @@ static int do_io_accounting(struct task_struct *task, char *buffer, int whole)
 			(unsigned long long)acct.read_bytes,
 			(unsigned long long)acct.write_bytes,
 			(unsigned long long)acct.cancelled_write_bytes);
-out_unlock:
-	mutex_unlock(&task->signal->cred_guard_mutex);
+	task_access_unlock(task);
 	return result;
 }
 
@@ -2949,10 +2943,10 @@ static int proc_tgid_io_accounting(struct task_struct *task, char *buffer)
 static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
 				struct pid *pid, struct task_struct *task)
 {
-	int err = lock_trace(task);
+	int err = task_access_lock(task, PTRACE_MODE_ATTACH);
 	if (!err) {
 		seq_printf(m, "%08x\n", task->personality);
-		unlock_trace(task);
+		task_access_unlock(task);
 	}
 	return err;
 }
-- 
1.7.7.6

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