git: 081d40b8ea24 - stable/13 - nfsd: Sanity check the ACL attribute

The branch stable/13 has been updated by rmacklem:

URL: https://cgit.FreeBSD.org/src/commit/?id=081d40b8ea244d0700dd2b6031f9722394e3ce09

commit 081d40b8ea244d0700dd2b6031f9722394e3ce09
Author:     Rick Macklem <rmacklem@FreeBSD.org>
AuthorDate: 2021-12-01 21:55:17 +0000
Commit:     Rick Macklem <rmacklem@FreeBSD.org>
CommitDate: 2021-12-15 01:32:27 +0000

    nfsd: Sanity check the ACL attribute
    
    When an ACL is presented to the NFSv4 server in
    Setattr or Verify, parsing of the ACL assumed a
    sane acecnt and sane sizes for the "who" strings.
    This patch adds sanity checks for these.
    
    The patch also fixes handling of an error
    return from nfsrv_dissectacl() for one broken
    case.
    
    PR:     260111
    
    (cherry picked from commit fd020f197d6ac481d36171ea69fe555eb911d673)
---
 sys/fs/nfs/nfs_commonacl.c  |  6 +++++-
 sys/fs/nfs/nfs_commonsubs.c | 10 ++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/sys/fs/nfs/nfs_commonacl.c b/sys/fs/nfs/nfs_commonacl.c
index 99a67edc044d..19492675e731 100644
--- a/sys/fs/nfs/nfs_commonacl.c
+++ b/sys/fs/nfs/nfs_commonacl.c
@@ -58,7 +58,11 @@ nfsrv_dissectace(struct nfsrv_descript *nd, struct acl_entry *acep,
 	flag = fxdr_unsigned(u_int32_t, *tl++);
 	mask = fxdr_unsigned(u_int32_t, *tl++);
 	len = fxdr_unsigned(int, *tl);
-	if (len < 0) {
+	/*
+	 * The RFCs do not specify a limit to the length of the "who", but
+	 * NFSV4_OPAQUELIMIT (1024) should be sufficient.
+	 */
+	if (len < 0 || len > NFSV4_OPAQUELIMIT) {
 		error = NFSERR_BADXDR;
 		goto nfsmout;
 	} else if (len == 0) {
diff --git a/sys/fs/nfs/nfs_commonsubs.c b/sys/fs/nfs/nfs_commonsubs.c
index 58d517b0b13d..29e33372e83e 100644
--- a/sys/fs/nfs/nfs_commonsubs.c
+++ b/sys/fs/nfs/nfs_commonsubs.c
@@ -1107,6 +1107,14 @@ nfsrv_dissectacl(struct nfsrv_descript *nd, NFSACL_T *aclp, int *aclerrp,
 	NFSM_DISSECT(tl, u_int32_t *, NFSX_UNSIGNED);
 	aclsize = NFSX_UNSIGNED;
 	acecnt = fxdr_unsigned(int, *tl);
+	/*
+	 * The RFCs do not define a fixed limit to the number of ACEs in
+	 * an ACL, but 10240 should be more than sufficient.
+	 */
+	if (acecnt < 0 || acecnt > 10240) {
+		error = NFSERR_BADXDR;
+		goto nfsmout;
+	}
 	if (acecnt > ACL_MAX_ENTRIES)
 		aceerr = NFSERR_ATTRNOTSUPP;
 	if (nfsrv_useacl == 0)
@@ -1492,6 +1500,8 @@ nfsv4_loadattr(struct nfsrv_descript *nd, vnode_t vp,
 			    } else {
 				error = nfsrv_dissectacl(nd, NULL, &aceerr,
 				    &cnt, p);
+				if (error)
+				    goto nfsmout;
 				*retcmpp = NFSERR_ATTRNOTSUPP;
 			    }
 			  }