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authorCasey Schaufler <casey@schaufler-ca.com>2017-09-28 14:54:50 -0700
committerJames Morris <james.l.morris@oracle.com>2017-11-02 11:26:57 +1100
commitd6d80cb57be45fc1a7d08c30526ab81ae9e7bc3d (patch)
treef39219dec9fe53e8684de04e4e2cea552f54d4bc /security
parente28aa8aeab433b62e85a2da8d9bff2ba81c2ea4e (diff)
downloadlwn-d6d80cb57be45fc1a7d08c30526ab81ae9e7bc3d.tar.gz
lwn-d6d80cb57be45fc1a7d08c30526ab81ae9e7bc3d.zip
Smack: Base support for overlayfs
Supply the Smack module hooks in support of overlayfs. Ensure that the Smack label of new files gets the correct value when a directory is transmuting. Original implementation by Romanini Daniele, with a few tweaks added. Signed-off-by: Romanini Daniele <daniele.romanini@aalto.fi> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
Diffstat (limited to 'security')
-rw-r--r--security/smack/smack_lsm.c79
1 files changed, 79 insertions, 0 deletions
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 319add31b4a4..569f28034116 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4605,6 +4605,82 @@ static int smack_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
return 0;
}
+static int smack_inode_copy_up(struct dentry *dentry, struct cred **new)
+{
+
+ struct task_smack *tsp;
+ struct smack_known *skp;
+ struct inode_smack *isp;
+ struct cred *new_creds = *new;
+
+ if (new_creds == NULL) {
+ new_creds = prepare_creds();
+ if (new_creds == NULL)
+ return -ENOMEM;
+ }
+
+ tsp = new_creds->security;
+
+ /*
+ * Get label from overlay inode and set it in create_sid
+ */
+ isp = d_inode(dentry->d_parent)->i_security;
+ skp = isp->smk_inode;
+ tsp->smk_task = skp;
+ *new = new_creds;
+ return 0;
+}
+
+static int smack_inode_copy_up_xattr(const char *name)
+{
+ /*
+ * Return 1 if this is the smack access Smack attribute.
+ */
+ if (strcmp(name, XATTR_NAME_SMACK) == 0)
+ return 1;
+
+ return -EOPNOTSUPP;
+}
+
+static int smack_dentry_create_files_as(struct dentry *dentry, int mode,
+ struct qstr *name,
+ const struct cred *old,
+ struct cred *new)
+{
+ struct task_smack *otsp = old->security;
+ struct task_smack *ntsp = new->security;
+ struct inode_smack *isp;
+ int may;
+
+ /*
+ * Use the process credential unless all of
+ * the transmuting criteria are met
+ */
+ ntsp->smk_task = otsp->smk_task;
+
+ /*
+ * the attribute of the containing directory
+ */
+ isp = d_inode(dentry->d_parent)->i_security;
+
+ if (isp->smk_flags & SMK_INODE_TRANSMUTE) {
+ rcu_read_lock();
+ may = smk_access_entry(otsp->smk_task->smk_known,
+ isp->smk_inode->smk_known,
+ &otsp->smk_task->smk_rules);
+ rcu_read_unlock();
+
+ /*
+ * If the directory is transmuting and the rule
+ * providing access is transmuting use the containing
+ * directory label instead of the process label.
+ */
+ if (may > 0 && (may & MAY_TRANSMUTE))
+ ntsp->smk_task = isp->smk_inode;
+ }
+ return 0;
+}
+
static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(ptrace_access_check, smack_ptrace_access_check),
LSM_HOOK_INIT(ptrace_traceme, smack_ptrace_traceme),
@@ -4740,6 +4816,9 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(inode_notifysecctx, smack_inode_notifysecctx),
LSM_HOOK_INIT(inode_setsecctx, smack_inode_setsecctx),
LSM_HOOK_INIT(inode_getsecctx, smack_inode_getsecctx),
+ LSM_HOOK_INIT(inode_copy_up, smack_inode_copy_up),
+ LSM_HOOK_INIT(inode_copy_up_xattr, smack_inode_copy_up_xattr),
+ LSM_HOOK_INIT(dentry_create_files_as, smack_dentry_create_files_as),
};