1 files changed, 80 insertions, 102 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index a314fd9af17c..c8d783f3b2ac 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -218,33 +218,24 @@ static int get_task_root(struct task_struct *task, struct path *root)
 	return result;
 }
 
-static int proc_cwd_link(struct dentry *dentry, struct path *path)
+static int proc_cwd_link(struct dentry *dentry, struct path *path,
+			 struct task_struct *task)
 {
-	struct task_struct *task = get_proc_task(d_inode(dentry));
 	int result = -ENOENT;
 
-	if (task) {
-		task_lock(task);
-		if (task->fs) {
-			get_fs_pwd(task->fs, path);
-			result = 0;
-		}
-		task_unlock(task);
-		put_task_struct(task);
+	task_lock(task);
+	if (task->fs) {
+		get_fs_pwd(task->fs, path);
+		result = 0;
 	}
+	task_unlock(task);
 	return result;
 }
 
-static int proc_root_link(struct dentry *dentry, struct path *path)
+static int proc_root_link(struct dentry *dentry, struct path *path,
+			  struct task_struct *task)
 {
-	struct task_struct *task = get_proc_task(d_inode(dentry));
-	int result = -ENOENT;
-
-	if (task) {
-		result = get_task_root(task, path);
-		put_task_struct(task);
-	}
-	return result;
+	return get_task_root(task, path);
 }
 
 /*
@@ -423,18 +414,24 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
 {
 	unsigned long wchan;
 	char symname[KSYM_NAME_LEN];
+	int err;
 
+	err = down_read_killable(&task->signal->exec_update_lock);
+	if (err)
+		return err;
 	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
 		goto print0;
 
 	wchan = get_wchan(task);
 	if (wchan && !lookup_symbol_name(wchan, symname)) {
 		seq_puts(m, symname);
+		up_read(&task->signal->exec_update_lock);
 		return 0;
 	}
 
 print0:
 	seq_putc(m, '0');
+	up_read(&task->signal->exec_update_lock);
 	return 0;
 }
 #endif /* CONFIG_KALLSYMS */
@@ -704,24 +701,7 @@ static int proc_pid_syscall(struct seq_file *m, struct pid_namespace *ns,
 /*                       Here the fs part begins                        */
 /************************************************************************/
 
-/* permission checks */
-static bool proc_fd_access_allowed(struct inode *inode)
-{
-	struct task_struct *task;
-	bool allowed = false;
-	/* Allow access to a task's file descriptors if it is us or we
-	 * may use ptrace attach to the process and find out that
-	 * information.
-	 */
-	task = get_proc_task(inode);
-	if (task) {
-		allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
-		put_task_struct(task);
-	}
-	return allowed;
-}
-
-int proc_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+int proc_nochmod_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		 struct iattr *attr)
 {
 	int error;
@@ -794,7 +774,7 @@ static int proc_pid_permission(struct mnt_idmap *idmap,
 
 
 static const struct inode_operations proc_def_inode_operations = {
-	.setattr	= proc_setattr,
+	.setattr	= proc_nochmod_setattr,
 };
 
 static int proc_single_show(struct seq_file *m, void *v)
@@ -1777,16 +1757,12 @@ static const struct file_operations proc_pid_set_comm_operations = {
 	.release	= single_release,
 };
 
-static int proc_exe_link(struct dentry *dentry, struct path *exe_path)
+static int proc_exe_link(struct dentry *dentry, struct path *exe_path,
+			 struct task_struct *task)
 {
-	struct task_struct *task;
 	struct file *exe_file;
 
-	task = get_proc_task(d_inode(dentry));
-	if (!task)
-		return -ENOENT;
 	exe_file = get_task_exe_file(task);
-	put_task_struct(task);
 	if (exe_file) {
 		*exe_path = exe_file->f_path;
 		path_get(&exe_file->f_path);
@@ -1796,26 +1772,42 @@ static int proc_exe_link(struct dentry *dentry, struct path *exe_path)
 		return -ENOENT;
 }
 
+static int call_proc_get_link(struct dentry *dentry, struct inode *inode, struct path *path_out)
+{
+	struct task_struct *task;
+	int ret;
+
+	task = get_proc_task(inode);
+	if (!task)
+		return -ENOENT;
+	ret = down_read_killable(&task->signal->exec_update_lock);
+	if (ret)
+		goto out_put_task;
+	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
+		ret = -EACCES;
+		goto out;
+	}
+	ret = PROC_I(inode)->op.proc_get_link(dentry, path_out, task);
+
+out:
+	up_read(&task->signal->exec_update_lock);
+out_put_task:
+	put_task_struct(task);
+	return ret;
+}
+
 static const char *proc_pid_get_link(struct dentry *dentry,
 				     struct inode *inode,
 				     struct delayed_call *done)
 {
 	struct path path;
-	int error = -EACCES;
+	int error;
 
 	if (!dentry)
 		return ERR_PTR(-ECHILD);
-
-	/* Are we allowed to snoop on the tasks file descriptors? */
-	if (!proc_fd_access_allowed(inode))
-		goto out;
-
-	error = PROC_I(inode)->op.proc_get_link(dentry, &path);
-	if (error)
-		goto out;
-
-	error = nd_jump_link(&path);
-out:
+	error = call_proc_get_link(dentry, inode, &path);
+	if (!error)
+		error = nd_jump_link(&path);
 	return ERR_PTR(error);
 }
 
@@ -1849,24 +1841,18 @@ static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int b
 	struct inode *inode = d_inode(dentry);
 	struct path path;
 
-	/* Are we allowed to snoop on the tasks file descriptors? */
-	if (!proc_fd_access_allowed(inode))
-		goto out;
-
-	error = PROC_I(inode)->op.proc_get_link(dentry, &path);
-	if (error)
-		goto out;
-
-	error = do_proc_readlink(&path, buffer, buflen);
-	path_put(&path);
-out:
+	error = call_proc_get_link(dentry, inode, &path);
+	if (!error) {
+		error = do_proc_readlink(&path, buffer, buflen);
+		path_put(&path);
+	}
 	return error;
 }
 
 const struct inode_operations proc_pid_link_inode_operations = {
 	.readlink	= proc_pid_readlink,
 	.get_link	= proc_pid_get_link,
-	.setattr	= proc_setattr,
+	.setattr	= proc_nochmod_setattr,
 };
 
 
@@ -2250,21 +2236,16 @@ static const struct dentry_operations tid_map_files_dentry_operations = {
 	.d_delete	= pid_delete_dentry,
 };
 
-static int map_files_get_link(struct dentry *dentry, struct path *path)
+static int map_files_get_link(struct dentry *dentry, struct path *path,
+			      struct task_struct *task)
 {
 	unsigned long vm_start, vm_end;
 	struct vm_area_struct *vma;
-	struct task_struct *task;
 	struct mm_struct *mm;
 	int rc;
 
 	rc = -ENOENT;
-	task = get_proc_task(d_inode(dentry));
-	if (!task)
-		goto out;
-
 	mm = get_task_mm(task);
-	put_task_struct(task);
 	if (!mm)
 		goto out;
 
@@ -2319,7 +2300,7 @@ proc_map_files_get_link(struct dentry *dentry,
 static const struct inode_operations proc_map_files_link_inode_operations = {
 	.readlink	= proc_pid_readlink,
 	.get_link	= proc_map_files_get_link,
-	.setattr	= proc_setattr,
+	.setattr	= proc_nochmod_setattr,
 };
 
 static struct dentry *
@@ -2360,17 +2341,15 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 	if (!task)
 		goto out;
 
-	result = ERR_PTR(-EACCES);
-	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
-		goto out_put_task;
-
 	result = ERR_PTR(-ENOENT);
 	if (dname_to_vma_addr(dentry, &vm_start, &vm_end))
 		goto out_put_task;
 
-	mm = get_task_mm(task);
-	if (!mm)
+	mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
+	if (IS_ERR(mm)) {
+		result = ERR_CAST(mm);
 		goto out_put_task;
+	}
 
 	result = ERR_PTR(-EINTR);
 	if (mmap_read_lock_killable(mm))
@@ -2398,7 +2377,7 @@ out:
 static const struct inode_operations proc_map_files_inode_operations = {
 	.lookup		= proc_map_files_lookup,
 	.permission	= proc_fd_permission,
-	.setattr	= proc_setattr,
+	.setattr	= proc_nochmod_setattr,
 };
 
 static int
@@ -2420,23 +2399,22 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
 	if (!task)
 		goto out;
 
-	ret = -EACCES;
-	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
-		goto out_put_task;
-
 	ret = 0;
 	if (!dir_emit_dots(file, ctx))
 		goto out_put_task;
 
-	mm = get_task_mm(task);
-	if (!mm)
+	mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
+	if (IS_ERR(mm)) {
+		ret = PTR_ERR(mm);
+		/* if the task has no mm, the directory should just be empty */
+		if (ret == -ESRCH)
+			ret = 0;
 		goto out_put_task;
+	}
 
 	ret = mmap_read_lock_killable(mm);
-	if (ret) {
-		mmput(mm);
-		goto out_put_task;
-	}
+	if (ret)
+		goto out_put_mm;
 
 	nr_files = 0;
 
@@ -2462,8 +2440,7 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
 		if (!p) {
 			ret = -ENOMEM;
 			mmap_read_unlock(mm);
-			mmput(mm);
-			goto out_put_task;
+			goto out_put_mm;
 		}
 
 		p->start = vma->vm_start;
@@ -2471,7 +2448,6 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
 		p->mode = vma->vm_file->f_mode;
 	}
 	mmap_read_unlock(mm);
-	mmput(mm);
 
 	for (i = 0; i < nr_files; i++) {
 		char buf[4 * sizeof(long) + 2];	/* max: %lx-%lx\0 */
@@ -2488,6 +2464,8 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
 		ctx->pos++;
 	}
 
+out_put_mm:
+	mmput(mm);
 out_put_task:
 	put_task_struct(task);
 out:
@@ -2885,7 +2863,7 @@ static struct dentry *proc_##LSM##_attr_dir_lookup(struct inode *dir, \
 static const struct inode_operations proc_##LSM##_attr_dir_inode_ops = { \
 	.lookup		= proc_##LSM##_attr_dir_lookup, \
 	.getattr	= pid_getattr, \
-	.setattr	= proc_setattr, \
+	.setattr	= proc_nochmod_setattr, \
 }
 
 #ifdef CONFIG_SECURITY_SMACK
@@ -2944,7 +2922,7 @@ static struct dentry *proc_attr_dir_lookup(struct inode *dir,
 static const struct inode_operations proc_attr_dir_inode_operations = {
 	.lookup		= proc_attr_dir_lookup,
 	.getattr	= pid_getattr,
-	.setattr	= proc_setattr,
+	.setattr	= proc_nochmod_setattr,
 };
 
 #endif
@@ -3460,7 +3438,7 @@ static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *de
 static const struct inode_operations proc_tgid_base_inode_operations = {
 	.lookup		= proc_tgid_base_lookup,
 	.getattr	= pid_getattr,
-	.setattr	= proc_setattr,
+	.setattr	= proc_nochmod_setattr,
 	.permission	= proc_pid_permission,
 };
 
@@ -3659,7 +3637,7 @@ static int proc_tid_comm_permission(struct mnt_idmap *idmap,
 }
 
 static const struct inode_operations proc_tid_comm_inode_operations = {
-		.setattr	= proc_setattr,
+		.setattr	= proc_nochmod_setattr,
 		.permission	= proc_tid_comm_permission,
 };
 
@@ -3788,7 +3766,7 @@ static const struct file_operations proc_tid_base_operations = {
 static const struct inode_operations proc_tid_base_inode_operations = {
 	.lookup		= proc_tid_base_lookup,
 	.getattr	= pid_getattr,
-	.setattr	= proc_setattr,
+	.setattr	= proc_nochmod_setattr,
 };
 
 static struct dentry *proc_task_instantiate(struct dentry *dentry,
@@ -4001,7 +3979,7 @@ static loff_t proc_dir_llseek(struct file *file, loff_t offset, int whence)
 static const struct inode_operations proc_task_inode_operations = {
 	.lookup		= proc_task_lookup,
 	.getattr	= proc_task_getattr,
-	.setattr	= proc_setattr,
+	.setattr	= proc_nochmod_setattr,
 	.permission	= proc_pid_permission,
 };