svn commit: r352833 - stable/12/sys/kern

[Konstantin Belousov]

Author: kib
Date: Sat Sep 28 07:33:08 2019
New Revision: 352833
URL: https://svnweb.freebsd.org/changeset/base/352833

Log:
  MFC r352582, r352585:
  Make non-ASLR pie base tunable.

Modified:
  stable/12/sys/kern/imgact_elf.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/kern/imgact_elf.c
==============================================================================
--- stable/12/sys/kern/imgact_elf.c	Sat Sep 28 03:33:07 2019	(r352832)
+++ stable/12/sys/kern/imgact_elf.c	Sat Sep 28 07:33:08 2019	(r352833)
@@ -136,6 +136,27 @@ SYSCTL_INT(_kern_elf32, OID_AUTO, read_exec, CTLFLAG_R
 #endif
 #endif
 
+static u_long __elfN(pie_base) = ET_DYN_LOAD_ADDR;
+static int
+sysctl_pie_base(SYSCTL_HANDLER_ARGS)
+{
+	u_long val;
+	int error;
+
+	val = __elfN(pie_base);
+	error = sysctl_handle_long(oidp, &val, 0, req);
+	if (error != 0 || req->newptr == NULL)
+		return (error);
+	if ((val & PAGE_MASK) != 0)
+		return (EINVAL);
+	__elfN(pie_base) = val;
+	return (0);
+}
+SYSCTL_PROC(__CONCAT(_kern_elf, __ELF_WORD_SIZE), OID_AUTO, pie_base,
+    CTLTYPE_ULONG | CTLFLAG_MPSAFE | CTLFLAG_RW, NULL, 0,
+    sysctl_pie_base, "LU",
+    "PIE load base without randomization");
+
 SYSCTL_NODE(__CONCAT(_kern_elf, __ELF_WORD_SIZE), OID_AUTO, aslr, CTLFLAG_RW, 0,
     "");
 #define	ASLR_NODE_OID	__CONCAT(__CONCAT(_kern_elf, __ELF_WORD_SIZE), _aslr)
@@ -1148,13 +1169,13 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *i
 		if (baddr == 0) {
 			if ((sv->sv_flags & SV_ASLR) == 0 ||
 			    (fctl0 & NT_FREEBSD_FCTL_ASLR_DISABLE) != 0)
-				et_dyn_addr = ET_DYN_LOAD_ADDR;
+				et_dyn_addr = __elfN(pie_base);
 			else if ((__elfN(pie_aslr_enabled) &&
 			    (imgp->proc->p_flag2 & P2_ASLR_DISABLE) == 0) ||
 			    (imgp->proc->p_flag2 & P2_ASLR_ENABLE) != 0)
 				et_dyn_addr = ET_DYN_ADDR_RAND;
 			else
-				et_dyn_addr = ET_DYN_LOAD_ADDR;
+				et_dyn_addr = __elfN(pie_base);
 		}
 	}