LSM/SELinux: show LSM mount options in /proc/mounts

This patch causes SELinux mount options to show up in /proc/mounts.  As
with other code in the area seq_put errors are ignored.  Other LSM's
will not have their mount options displayed until they fill in their own
security_sb_show_options() function.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 11 insertions, 3 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 4fc302c2a0e0..4f6f7635b59c 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -750,7 +750,7 @@ struct proc_fs_info {
         const char *str;
 };
 
-static void show_sb_opts(struct seq_file *m, struct super_block *sb)
+static int show_sb_opts(struct seq_file *m, struct super_block *sb)
 {
         static const struct proc_fs_info fs_info[] = {
                 { MS_SYNCHRONOUS, ",sync" },
@@ -764,6 +764,8 @@ static void show_sb_opts(struct seq_file *m, struct super_block *sb)
                 if (sb->s_flags & fs_infop->flag)
                         seq_puts(m, fs_infop->str);
         }
+
+        return security_sb_show_options(m, sb);
 }
 
 static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
@@ -806,11 +808,14 @@ static int show_vfsmnt(struct seq_file *m, void *v)
         seq_putc(m, ' ');
         show_type(m, mnt->mnt_sb);
         seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
-        show_sb_opts(m, mnt->mnt_sb);
+        err = show_sb_opts(m, mnt->mnt_sb);
+        if (err)
+                goto out;
         show_mnt_opts(m, mnt);
         if (mnt->mnt_sb->s_op->show_options)
                 err = mnt->mnt_sb->s_op->show_options(m, mnt);
         seq_puts(m, " 0 0\n");
+out:
         return err;
 }
 
@@ -865,10 +870,13 @@ static int show_mountinfo(struct seq_file *m, void *v)
         seq_putc(m, ' ');
         mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
         seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
-        show_sb_opts(m, sb);
+        err = show_sb_opts(m, sb);
+        if (err)
+                goto out;
         if (sb->s_op->show_options)
                 err = sb->s_op->show_options(m, mnt);
         seq_putc(m, '\n');
+out:
         return err;
 }