LSM: Move security_path_chmod()/security_path_chown() to after mutex_lock().

We should call security_path_chmod()/security_path_chown() after mutex_lock()
in order to avoid races.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 15 insertions, 21 deletions

diff --git a/fs/open.c b/fs/open.c
index 201041dfca57..b4b31d277f3a 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -619,17 +619,17 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode)
         err = mnt_want_write_file(file);
         if (err)
                 goto out_putf;
+        mutex_lock(&inode->i_mutex);
         err = security_path_chmod(dentry, file->f_vfsmnt, mode);
         if (err)
-                goto out_drop_write;
-        mutex_lock(&inode->i_mutex);
+                goto out_unlock;
         if (mode == (mode_t) -1)
                 mode = inode->i_mode;
         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
         err = notify_change(dentry, &newattrs);
+out_unlock:
         mutex_unlock(&inode->i_mutex);
-out_drop_write:
         mnt_drop_write(file->f_path.mnt);
 out_putf:
         fput(file);
@@ -652,17 +652,17 @@ SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode)
         error = mnt_want_write(path.mnt);
         if (error)
                 goto dput_and_out;
+        mutex_lock(&inode->i_mutex);
         error = security_path_chmod(path.dentry, path.mnt, mode);
         if (error)
-                goto out_drop_write;
-        mutex_lock(&inode->i_mutex);
+                goto out_unlock;
         if (mode == (mode_t) -1)
                 mode = inode->i_mode;
         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
         error = notify_change(path.dentry, &newattrs);
+out_unlock:
         mutex_unlock(&inode->i_mutex);
-out_drop_write:
         mnt_drop_write(path.mnt);
 dput_and_out:
         path_put(&path);
@@ -675,9 +675,9 @@ SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_t, mode)
         return sys_fchmodat(AT_FDCWD, filename, mode);
 }
 
-static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
+static int chown_common(struct path *path, uid_t user, gid_t group)
 {
-        struct inode *inode = dentry->d_inode;
+        struct inode *inode = path->dentry->d_inode;
         int error;
         struct iattr newattrs;
 
@@ -694,7 +694,9 @@ static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
                 newattrs.ia_valid |=
                         ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
         mutex_lock(&inode->i_mutex);
-        error = notify_change(dentry, &newattrs);
+        error = security_path_chown(path, user, group);
+        if (!error)
+                error = notify_change(path->dentry, &newattrs);
         mutex_unlock(&inode->i_mutex);
 
         return error;
@@ -711,9 +713,7 @@ SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
         error = mnt_want_write(path.mnt);
         if (error)
                 goto out_release;
-        error = security_path_chown(&path, user, group);
-        if (!error)
-                error = chown_common(path.dentry, user, group);
+        error = chown_common(&path, user, group);
         mnt_drop_write(path.mnt);
 out_release:
         path_put(&path);
@@ -738,9 +738,7 @@ SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
         error = mnt_want_write(path.mnt);
         if (error)
                 goto out_release;
-        error = security_path_chown(&path, user, group);
-        if (!error)
-                error = chown_common(path.dentry, user, group);
+        error = chown_common(&path, user, group);
         mnt_drop_write(path.mnt);
 out_release:
         path_put(&path);
@@ -759,9 +757,7 @@ SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group
         error = mnt_want_write(path.mnt);
         if (error)
                 goto out_release;
-        error = security_path_chown(&path, user, group);
-        if (!error)
-                error = chown_common(path.dentry, user, group);
+        error = chown_common(&path, user, group);
         mnt_drop_write(path.mnt);
 out_release:
         path_put(&path);
@@ -784,9 +780,7 @@ SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
                 goto out_fput;
         dentry = file->f_path.dentry;
         audit_inode(NULL, dentry);
-        error = security_path_chown(&file->f_path, user, group);
-        if (!error)
-                error = chown_common(dentry, user, group);
+        error = chown_common(&file->f_path, user, group);
         mnt_drop_write(file->f_path.mnt);
 out_fput:
         fput(file);