SELinux: Add selfattr hooks

Add hooks for setselfattr and getselfattr. These hooks are not very
different from their setprocattr and getprocattr equivalents, and
much of the code is shared.

Cc: selinux@vger.kernel.org
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index f2423dfd19cd41dae69e9d737fdee6deb7baf15e..b6c7930a3ab29cb01df39fb2d9919d82247b050d 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6285,8 +6285,8 @@ static void selinux_d_instantiate(struct dentry *dentry, struct inode *inode)
                inode_doinit_with_dentry(inode, dentry);
 }
 
-static int selinux_getprocattr(struct task_struct *p,
-                              const char *name, char **value)
+static int selinux_lsm_getattr(unsigned int attr, struct task_struct *p,
+                              char **value)
 {
        const struct task_security_struct *__tsec;
        u32 sid;
@@ -6303,20 +6303,27 @@ static int selinux_getprocattr(struct task_struct *p,
                        goto bad;
        }
 
-       if (!strcmp(name, "current"))
+       switch (attr) {
+       case LSM_ATTR_CURRENT:
                sid = __tsec->sid;
-       else if (!strcmp(name, "prev"))
+               break;
+       case LSM_ATTR_PREV:
                sid = __tsec->osid;
-       else if (!strcmp(name, "exec"))
+               break;
+       case LSM_ATTR_EXEC:
                sid = __tsec->exec_sid;
-       else if (!strcmp(name, "fscreate"))
+               break;
+       case LSM_ATTR_FSCREATE:
                sid = __tsec->create_sid;
-       else if (!strcmp(name, "keycreate"))
+               break;
+       case LSM_ATTR_KEYCREATE:
                sid = __tsec->keycreate_sid;
-       else if (!strcmp(name, "sockcreate"))
+               break;
+       case LSM_ATTR_SOCKCREATE:
                sid = __tsec->sockcreate_sid;
-       else {
-               error = -EINVAL;
+               break;
+       default:
+               error = -EOPNOTSUPP;
                goto bad;
        }
        rcu_read_unlock();
@@ -6334,7 +6341,7 @@ bad:
        return error;
 }
 
-static int selinux_setprocattr(const char *name, void *value, size_t size)
+static int selinux_lsm_setattr(u64 attr, void *value, size_t size)
 {
        struct task_security_struct *tsec;
        struct cred *new;
@@ -6345,23 +6352,31 @@ static int selinux_setprocattr(const char *name, void *value, size_t size)
        /*
         * Basic control over ability to set these attributes at all.
         */
-       if (!strcmp(name, "exec"))
+       switch (attr) {
+       case LSM_ATTR_EXEC:
                error = avc_has_perm(mysid, mysid, SECCLASS_PROCESS,
                                     PROCESS__SETEXEC, NULL);
-       else if (!strcmp(name, "fscreate"))
+               break;
+       case LSM_ATTR_FSCREATE:
                error = avc_has_perm(mysid, mysid, SECCLASS_PROCESS,
                                     PROCESS__SETFSCREATE, NULL);
-       else if (!strcmp(name, "keycreate"))
+               break;
+       case LSM_ATTR_KEYCREATE:
                error = avc_has_perm(mysid, mysid, SECCLASS_PROCESS,
                                     PROCESS__SETKEYCREATE, NULL);
-       else if (!strcmp(name, "sockcreate"))
+               break;
+       case LSM_ATTR_SOCKCREATE:
                error = avc_has_perm(mysid, mysid, SECCLASS_PROCESS,
                                     PROCESS__SETSOCKCREATE, NULL);
-       else if (!strcmp(name, "current"))
+               break;
+       case LSM_ATTR_CURRENT:
                error = avc_has_perm(mysid, mysid, SECCLASS_PROCESS,
                                     PROCESS__SETCURRENT, NULL);
-       else
-               error = -EINVAL;
+               break;
+       default:
+               error = -EOPNOTSUPP;
+               break;
+       }
        if (error)
                return error;
 
@@ -6373,13 +6388,14 @@ static int selinux_setprocattr(const char *name, void *value, size_t size)
                }
                error = security_context_to_sid(value, size,
                                                &sid, GFP_KERNEL);
-               if (error == -EINVAL && !strcmp(name, "fscreate")) {
+               if (error == -EINVAL && attr == LSM_ATTR_FSCREATE) {
                        if (!has_cap_mac_admin(true)) {
                                struct audit_buffer *ab;
                                size_t audit_size;
 
-                               /* We strip a nul only if it is at the end, otherwise the
-                                * context contains a nul and we should audit that */
+                               /* We strip a nul only if it is at the end,
+                                * otherwise the context contains a nul and
+                                * we should audit that */
                                if (str[size - 1] == '\0')
                                        audit_size = size - 1;
                                else
@@ -6390,7 +6406,8 @@ static int selinux_setprocattr(const char *name, void *value, size_t size)
                                if (!ab)
                                        return error;
                                audit_log_format(ab, "op=fscreate invalid_context=");
-                               audit_log_n_untrustedstring(ab, value, audit_size);
+                               audit_log_n_untrustedstring(ab, value,
+                                                           audit_size);
                                audit_log_end(ab);
 
                                return error;
@@ -6413,11 +6430,11 @@ static int selinux_setprocattr(const char *name, void *value, size_t size)
           checks and may_create for the file creation checks. The
           operation will then fail if the context is not permitted. */
        tsec = selinux_cred(new);
-       if (!strcmp(name, "exec")) {
+       if (attr == LSM_ATTR_EXEC) {
                tsec->exec_sid = sid;
-       } else if (!strcmp(name, "fscreate")) {
+       } else if (attr == LSM_ATTR_FSCREATE) {
                tsec->create_sid = sid;
-       } else if (!strcmp(name, "keycreate")) {
+       } else if (attr == LSM_ATTR_KEYCREATE) {
                if (sid) {
                        error = avc_has_perm(mysid, sid,
                                             SECCLASS_KEY, KEY__CREATE, NULL);
@@ -6425,9 +6442,9 @@ static int selinux_setprocattr(const char *name, void *value, size_t size)
                                goto abort_change;
                }
                tsec->keycreate_sid = sid;
-       } else if (!strcmp(name, "sockcreate")) {
+       } else if (attr == LSM_ATTR_SOCKCREATE) {
                tsec->sockcreate_sid = sid;
-       } else if (!strcmp(name, "current")) {
+       } else if (attr == LSM_ATTR_CURRENT) {
                error = -EINVAL;
                if (sid == 0)
                        goto abort_change;
@@ -6469,6 +6486,67 @@ abort_change:
        return error;
 }
 
+static int selinux_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
+                              size_t *size, u32 flags)
+{
+       char *value;
+       size_t total_len;
+       int len;
+       int rc = 0;
+
+       len = selinux_lsm_getattr(attr, current, &value);
+       if (len < 0)
+               return len;
+
+       total_len = ALIGN(struct_size(ctx, ctx, len), 8);
+
+       if (total_len > *size)
+               rc = -E2BIG;
+       else if (ctx)
+               rc = lsm_fill_user_ctx(ctx, value, len, LSM_ID_SELINUX, 0);
+
+       kfree(value);
+       *size = total_len;
+       if (rc < 0)
+               return rc;
+       return 1;
+}
+
+static int selinux_setselfattr(unsigned int attr, struct lsm_ctx *ctx,
+                              size_t size, u32 flags)
+{
+       int rc;
+
+       rc = selinux_lsm_setattr(attr, ctx->ctx, ctx->ctx_len);
+       if (rc > 0)
+               return 0;
+       return rc;
+}
+
+static int selinux_getprocattr(struct task_struct *p,
+                              const char *name, char **value)
+{
+       unsigned int attr = lsm_name_to_attr(name);
+       int rc;
+
+       if (attr) {
+               rc = selinux_lsm_getattr(attr, p, value);
+               if (rc != -EOPNOTSUPP)
+                       return rc;
+       }
+
+       return -EINVAL;
+}
+
+static int selinux_setprocattr(const char *name, void *value, size_t size)
+{
+       int attr = lsm_name_to_attr(name);
+
+       if (attr)
+               return selinux_lsm_setattr(attr, value, size);
+       return -EINVAL;
+}
+
 static int selinux_ismaclabel(const char *name)
 {
        return (strcmp(name, XATTR_SELINUX_SUFFIX) == 0);
@@ -7097,6 +7175,8 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = {
 
        LSM_HOOK_INIT(d_instantiate, selinux_d_instantiate),
 
+       LSM_HOOK_INIT(getselfattr, selinux_getselfattr),
+       LSM_HOOK_INIT(setselfattr, selinux_setselfattr),
        LSM_HOOK_INIT(getprocattr, selinux_getprocattr),
        LSM_HOOK_INIT(setprocattr, selinux_setprocattr),