LU-16012 sec: fix detection of SELinux enforcement

On newer distros (e.g. RHEL 9.0), on which selinux_is_enabled() does
not exist anymore, the only way to find out if SELinux is enforced
when initializing the security context is to fetch the length of the
security attribute name. If it is 0, we conclude SELinux is disabled.

Lustre-change: https://review.whamcloud.com/48049
Lustre-commit: 155cbc22ba4f758cf9eec415f36f940ca2b23de9

Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: Ifcdcb8ffbb7f9ad50d16d7d3317e94d0d212fa42
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Yingjin Qian <qian@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/48422
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Qian Yingjin <qian@ddn.com>

diff --git a/lustre/llite/dir.c b/lustre/llite/dir.c
index cdae535..c7eafbb 100644 (file)
--- a/lustre/llite/dir.c
+++ b/lustre/llite/dir.c
@@ -533,7 +533,8 @@ static int ll_dir_setdirstripe(struct dentry *dparent, struct lmv_user_md *lump,
                /* selinux_dentry_init_security() uses dentry->d_parent and name
                 * to determine the security context for the file. So our fake
                 * dentry should be real enough for this purpose. */
-               err = ll_dentry_init_security(&dentry, mode, &dentry.d_name,
+               err = ll_dentry_init_security(parent,
+                                             &dentry, mode, &dentry.d_name,
                                              &op_data->op_file_secctx_name,
                                              &op_data->op_file_secctx,
                                              &op_data->op_file_secctx_size);

diff --git a/lustre/llite/llite_internal.h b/lustre/llite/llite_internal.h
index 2f2be4e..12329ea 100644 (file)
--- a/lustre/llite/llite_internal.h
+++ b/lustre/llite/llite_internal.h
@@ -501,7 +501,8 @@ static inline void obd_connect_set_secctx(struct obd_connect_data *data)
 #endif
 }
 
-int ll_dentry_init_security(struct dentry *dentry, int mode, struct qstr *name,
+int ll_dentry_init_security(struct inode *parent, struct dentry *dentry,
+                           int mode, struct qstr *name,
                            const char **secctx_name, void **secctx,
                            __u32 *secctx_size);
 int ll_inode_init_security(struct dentry *dentry, struct inode *inode,

diff --git a/lustre/llite/namei.c b/lustre/llite/namei.c
index 5d30286..7a51b5f 100644 (file)
--- a/lustre/llite/namei.c
+++ b/lustre/llite/namei.c
@@ -1024,7 +1024,8 @@ static struct dentry *ll_lookup_it(struct inode *parent, struct dentry *dentry,
 
        if (it->it_op & IT_CREAT &&
            ll_i2sbi(parent)->ll_flags & LL_SBI_FILE_SECCTX) {
-               rc = ll_dentry_init_security(dentry, it->it_create_mode,
+               rc = ll_dentry_init_security(parent,
+                                            dentry, it->it_create_mode,
                                             &dentry->d_name,
                                             &op_data->op_file_secctx_name,
                                             &op_data->op_file_secctx,
@@ -1700,7 +1701,8 @@ again:
                ll_qos_mkdir_prep(op_data, dir);
 
        if (sbi->ll_flags & LL_SBI_FILE_SECCTX) {
-               err = ll_dentry_init_security(dchild, mode, &dchild->d_name,
+               err = ll_dentry_init_security(dir,
+                                             dchild, mode, &dchild->d_name,
                                              &op_data->op_file_secctx_name,
                                              &op_data->op_file_secctx,
                                              &op_data->op_file_secctx_size);

diff --git a/lustre/llite/xattr_security.c b/lustre/llite/xattr_security.c
index 3993700..caf89be 100644 (file)
--- a/lustre/llite/xattr_security.c
+++ b/lustre/llite/xattr_security.c
@@ -50,7 +50,8 @@
 /*
  * Check for LL_SBI_FILE_SECCTX before calling.
  */
-int ll_dentry_init_security(struct dentry *dentry, int mode, struct qstr *name,
+int ll_dentry_init_security(struct inode *parent, struct dentry *dentry,
+                           int mode, struct qstr *name,
                            const char **secctx_name, void **secctx,
                            __u32 *secctx_size)
 {
@@ -73,6 +74,15 @@ int ll_dentry_init_security(struct dentry *dentry, int mode, struct qstr *name,
        if (!selinux_is_enabled())
                return 0;
 
+       /* fetch length of security xattr name */
+       rc = security_inode_listsecurity(parent, NULL, 0);
+       /* xattr name length == 0 means SELinux is disabled */
+       if (rc == 0)
+               return 0;
+       /* we support SELinux only */
+       if (rc != strlen(XATTR_NAME_SELINUX) + 1)
+               return -EOPNOTSUPP;
+
        rc = security_dentry_init_security(dentry, mode, name, secctx,
                                           secctx_size);
        /* Usually, security_dentry_init_security() returns -EOPNOTSUPP when