[patch] LSM/SELinux: show LSM mount options in /proc/mounts

From: Miklos Szeredi
Date: Thu Jul 03 2008 - 10:22:27 EST


Al, could you please add this to your 2.6.27 queue?

Thanks,
Miklos

----
From: Eric Paris <eparis@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
---
fs/namespace.c | 14 +++++++++--
include/linux/security.h | 9 +++++++
security/dummy.c | 6 +++++
security/security.c | 5 ++++
security/selinux/hooks.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++-
5 files changed, 85 insertions(+), 4 deletions(-)

Index: linux-2.6/include/linux/security.h
===================================================================
--- linux-2.6.orig/include/linux/security.h 2008-07-03 16:10:08.000000000 +0200
+++ linux-2.6/include/linux/security.h 2008-07-03 16:11:35.000000000 +0200
@@ -79,6 +79,7 @@ struct xfrm_selector;
struct xfrm_policy;
struct xfrm_state;
struct xfrm_user_sec_ctx;
+struct seq_file;

extern int cap_netlink_send(struct sock *sk, struct sk_buff *skb);
extern int cap_netlink_recv(struct sk_buff *skb, int cap);
@@ -1328,6 +1329,7 @@ struct security_operations {
void (*sb_free_security) (struct super_block *sb);
int (*sb_copy_data) (char *orig, char *copy);
int (*sb_kern_mount) (struct super_block *sb, void *data);
+ int (*sb_show_options) (struct seq_file *m, struct super_block *sb);
int (*sb_statfs) (struct dentry *dentry);
int (*sb_mount) (char *dev_name, struct path *path,
char *type, unsigned long flags, void *data);
@@ -1606,6 +1608,7 @@ int security_sb_alloc(struct super_block
void security_sb_free(struct super_block *sb);
int security_sb_copy_data(char *orig, char *copy);
int security_sb_kern_mount(struct super_block *sb, void *data);
+int security_sb_show_options(struct seq_file *m, struct super_block *sb);
int security_sb_statfs(struct dentry *dentry);
int security_sb_mount(char *dev_name, struct path *path,
char *type, unsigned long flags, void *data);
@@ -1881,6 +1884,12 @@ static inline int security_sb_kern_mount
return 0;
}

+static inline int security_sb_show_options(struct seq_file *m,
+ struct super_block *sb)
+{
+ return 0;
+}
+
static inline int security_sb_statfs(struct dentry *dentry)
{
return 0;
Index: linux-2.6/security/dummy.c
===================================================================
--- linux-2.6.orig/security/dummy.c 2008-07-03 16:10:08.000000000 +0200
+++ linux-2.6/security/dummy.c 2008-07-03 16:11:35.000000000 +0200
@@ -193,6 +193,11 @@ static int dummy_sb_kern_mount (struct s
return 0;
}

+static int dummy_sb_show_options(struct seq_file *m, struct super_block *sb)
+{
+ return 0;
+}
+
static int dummy_sb_statfs (struct dentry *dentry)
{
return 0;
@@ -1087,6 +1092,7 @@ void security_fixup_ops (struct security
set_to_dummy_if_null(ops, sb_free_security);
set_to_dummy_if_null(ops, sb_copy_data);
set_to_dummy_if_null(ops, sb_kern_mount);
+ set_to_dummy_if_null(ops, sb_show_options);
set_to_dummy_if_null(ops, sb_statfs);
set_to_dummy_if_null(ops, sb_mount);
set_to_dummy_if_null(ops, sb_check_sb);
Index: linux-2.6/security/security.c
===================================================================
--- linux-2.6.orig/security/security.c 2008-07-03 16:10:08.000000000 +0200
+++ linux-2.6/security/security.c 2008-07-03 16:11:35.000000000 +0200
@@ -291,6 +291,11 @@ int security_sb_kern_mount(struct super_
return security_ops->sb_kern_mount(sb, data);
}

+int security_sb_show_options(struct seq_file *m, struct super_block *sb)
+{
+ return security_ops->sb_show_options(m, sb);
+}
+
int security_sb_statfs(struct dentry *dentry)
{
return security_ops->sb_statfs(dentry);
Index: linux-2.6/security/selinux/hooks.c
===================================================================
--- linux-2.6.orig/security/selinux/hooks.c 2008-07-03 16:10:08.000000000 +0200
+++ linux-2.6/security/selinux/hooks.c 2008-07-03 16:11:35.000000000 +0200
@@ -9,7 +9,8 @@
* James Morris <jmorris@xxxxxxxxxx>
*
* Copyright (C) 2001,2002 Networks Associates Technology, Inc.
- * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@xxxxxxxxxx>
+ * Copyright (C) 2003-2008 Red Hat, Inc., James Morris <jmorris@xxxxxxxxxx>
+ * Eric Paris <eparis@xxxxxxxxxx>
* Copyright (C) 2004-2005 Trusted Computer Solutions, Inc.
* <dgoeddel@xxxxxxxxxxxxx>
* Copyright (C) 2006, 2007 Hewlett-Packard Development Company, L.P.
@@ -956,6 +957,57 @@ out_err:
return rc;
}

+void selinux_write_opts(struct seq_file *m, struct security_mnt_opts *opts)
+{
+ int i;
+ char *prefix;
+
+ for (i = 0; i < opts->num_mnt_opts; i++) {
+ char *has_comma = strchr(opts->mnt_opts[i], ',');
+
+ switch (opts->mnt_opts_flags[i]) {
+ case CONTEXT_MNT:
+ prefix = CONTEXT_STR;
+ break;
+ case FSCONTEXT_MNT:
+ prefix = FSCONTEXT_STR;
+ break;
+ case ROOTCONTEXT_MNT:
+ prefix = ROOTCONTEXT_STR;
+ break;
+ case DEFCONTEXT_MNT:
+ prefix = DEFCONTEXT_STR;
+ break;
+ default:
+ BUG();
+ };
+ /* we need a comma before each option */
+ seq_putc(m, ',');
+ seq_puts(m, prefix);
+ if (has_comma)
+ seq_putc(m, '\"');
+ seq_puts(m, opts->mnt_opts[i]);
+ if (has_comma)
+ seq_putc(m, '\"');
+ }
+}
+
+static int selinux_sb_show_options(struct seq_file *m, struct super_block *sb)
+{
+ struct security_mnt_opts opts;
+ int rc;
+
+ rc = selinux_get_mnt_opts(sb, &opts);
+ if (rc)
+ return rc;
+
+ selinux_write_opts(m, &opts);
+
+ security_free_mnt_opts(&opts);
+
+ return rc;
+}
+
static inline u16 inode_mode_to_security_class(umode_t mode)
{
switch (mode & S_IFMT) {
@@ -5343,6 +5395,7 @@ static struct security_operations selinu
.sb_free_security = selinux_sb_free_security,
.sb_copy_data = selinux_sb_copy_data,
.sb_kern_mount = selinux_sb_kern_mount,
+ .sb_show_options = selinux_sb_show_options,
.sb_statfs = selinux_sb_statfs,
.sb_mount = selinux_mount,
.sb_umount = selinux_umount,
Index: linux-2.6/fs/namespace.c
===================================================================
--- linux-2.6.orig/fs/namespace.c 2008-07-03 16:10:08.000000000 +0200
+++ linux-2.6/fs/namespace.c 2008-07-03 16:11:35.000000000 +0200
@@ -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
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 *
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_fil
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;
}

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