From: Olga Kornievskaia <kolga@xxxxxxxxxx>
Add a new hook that takes an existing super block and a new mount
with new options and determines if new options confict with an
existing mount or not.
Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx>
---
include/linux/lsm_hook_defs.h | 1 +
include/linux/lsm_hooks.h | 6 ++++
include/linux/security.h | 1 +
security/security.c | 7 +++++
security/selinux/hooks.c | 54 +++++++++++++++++++++++++++++++++++
5 files changed, 69 insertions(+)
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 7aaa753b8608..fbfc07d0b3d5 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -62,6 +62,7 @@ LSM_HOOK(int, 0, sb_alloc_security, struct super_block *sb)
LSM_HOOK(void, LSM_RET_VOID, sb_free_security, struct super_block *sb)
LSM_HOOK(void, LSM_RET_VOID, sb_free_mnt_opts, void *mnt_opts)
LSM_HOOK(int, 0, sb_eat_lsm_opts, char *orig, void **mnt_opts)
+LSM_HOOK(int, 0, sb_do_mnt_opts_match, struct super_block *sb, void *mnt_opts)
LSM_HOOK(int, 0, sb_remount, struct super_block *sb, void *mnt_opts)
LSM_HOOK(int, 0, sb_kern_mount, struct super_block *sb)
LSM_HOOK(int, 0, sb_show_options, struct seq_file *m, struct super_block *sb)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index a19adef1f088..a11b062c1847 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -142,6 +142,12 @@
* @orig the original mount data copied from userspace.
* @copy copied data which will be passed to the security module.
* Returns 0 if the copy was successful.
+ * @sb_do_mnt_opts_match:
+ * Determine if the existing mount options are compatible with the new
+ * mount options being used.
+ * @sb superblock being compared
+ * @mnt_opts new mount options
+ * Return 1 if options are the same.
* @sb_remount:
* Extracts security system specific mount options and verifies no changes
* are being made to those options.
diff --git a/include/linux/security.h b/include/linux/security.h
index c35ea0ffccd9..07026db7304d 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -291,6 +291,7 @@ int security_sb_alloc(struct super_block *sb);
void security_sb_free(struct super_block *sb);
void security_free_mnt_opts(void **mnt_opts);
int security_sb_eat_lsm_opts(char *options, void **mnt_opts);
+int security_sb_do_mnt_opts_match(struct super_block *sb, void *mnt_opts);
int security_sb_remount(struct super_block *sb, void *mnt_opts);
int security_sb_kern_mount(struct super_block *sb);
int security_sb_show_options(struct seq_file *m, struct super_block *sb);
diff --git a/security/security.c b/security/security.c
index 7b09cfbae94f..dae380916c6a 100644
--- a/security/security.c
+++ b/security/security.c
@@ -890,6 +890,13 @@ int security_sb_eat_lsm_opts(char *options, void **mnt_opts)
}
EXPORT_SYMBOL(security_sb_eat_lsm_opts);
+int security_sb_do_mnt_opts_match(struct super_block *sb,
+ void *mnt_opts)
+{
+ return call_int_hook(sb_do_mnt_opts_match, 0, sb, mnt_opts);
+}
+EXPORT_SYMBOL(security_sb_do_mnt_opts_match);
+
int security_sb_remount(struct super_block *sb,
void *mnt_opts)
{
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 644b17ec9e63..aaa3a725da94 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2656,6 +2656,59 @@ static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts)
return rc;
}
+static int selinux_sb_do_mnt_opts_match(struct super_block *sb, void *mnt_opts)
+{
+ struct selinux_mnt_opts *opts = mnt_opts;
+ struct superblock_security_struct *sbsec = sb->s_security;
+ u32 sid;
+ int rc;
+
+ /* superblock not initialized (i.e. no options) - reject if any
+ * options specified, otherwise accept
+ */
+ if (!(sbsec->flags & SE_SBINITIALIZED))
+ return opts ? 0 : 1;
+
+ /* superblock initialized and no options specified - reject if
+ * superblock has any options set, otherwise accept
+ */
+ if (!opts)
+ return (sbsec->flags & SE_MNTMASK) ? 0 : 1;
+
+ if (opts->fscontext) {
+ rc = parse_sid(sb, opts->fscontext, &sid);
+ if (rc)
+ return 0;
+ if (bad_option(sbsec, FSCONTEXT_MNT, sbsec->sid, sid))
+ return 0;
+ }
+ if (opts->context) {
+ rc = parse_sid(sb, opts->context, &sid);
+ if (rc)
+ return 0;
+ if (bad_option(sbsec, CONTEXT_MNT, sbsec->mntpoint_sid, sid))
+ return 0;
+ }
+ if (opts->rootcontext) {
+ struct inode_security_struct *root_isec;
+
+ root_isec = backing_inode_security(sb->s_root);
+ rc = parse_sid(sb, opts->rootcontext, &sid);
+ if (rc)
+ return 0;
+ if (bad_option(sbsec, ROOTCONTEXT_MNT, root_isec->sid, sid))
+ return 0;
+ }
+ if (opts->defcontext) {
+ rc = parse_sid(sb, opts->defcontext, &sid);
+ if (rc)
+ return 0;
+ if (bad_option(sbsec, DEFCONTEXT_MNT, sbsec->def_sid, sid))
+ return 0;
+ }
+ return 1;
+}
+
static int selinux_sb_remount(struct super_block *sb, void *mnt_opts)
{
struct selinux_mnt_opts *opts = mnt_opts;
@@ -6984,6 +7037,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(sb_free_security, selinux_sb_free_security),
LSM_HOOK_INIT(sb_free_mnt_opts, selinux_free_mnt_opts),
+ LSM_HOOK_INIT(sb_do_mnt_opts_match, selinux_sb_do_mnt_opts_match),
LSM_HOOK_INIT(sb_remount, selinux_sb_remount),
LSM_HOOK_INIT(sb_kern_mount, selinux_sb_kern_mount),
LSM_HOOK_INIT(sb_show_options, selinux_sb_show_options),
--
2.27.0
