From 9df1c38bbc816bbac7b85701971478bf976c68c4 Mon Sep 17 00:00:00 2001
From: Brooks Davis <brooks@FreeBSD.org>
Date: Wed, 15 Apr 2020 20:23:55 +0000
Subject: [PATCH] Export argc, argv, envc, envv, and ps_strings in auxargs.

This simplifies discovery of these values, potentially with reducing the
number of syscalls we need to make at runtime.  Longer term, we wish to
convert the startup process to pass an auxargs pointer to _start() and
use that rather than walking off the end of envv.  This is cleaner,
more C-friendly, and for systems with strong bounds (e.g. CHERI)
necessary.

Reviewed by:	kib
Obtained from:	CheriBSD
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D24407
---
 sys/compat/freebsd32/freebsd32_misc.c | 2 ++
 sys/kern/imgact_elf.c                 | 5 +++++
 sys/kern/kern_exec.c                  | 2 ++
 sys/sys/elf_common.h                  | 7 ++++++-
 sys/sys/imgact.h                      | 2 ++
 5 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/sys/compat/freebsd32/freebsd32_misc.c b/sys/compat/freebsd32/freebsd32_misc.c
index 9480d437bd9a..89088a2aba42 100644
--- a/sys/compat/freebsd32/freebsd32_misc.c
+++ b/sys/compat/freebsd32/freebsd32_misc.c
@@ -3237,6 +3237,7 @@ freebsd32_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	/*
 	 * Fill in "ps_strings" struct for ps, w, etc.
 	 */
+	imgp->argv = vectp;
 	if (suword32(&arginfo->ps_argvstr, (u_int32_t)(intptr_t)vectp) != 0 ||
 	    suword32(&arginfo->ps_nargvstr, argc) != 0)
 		return (EFAULT);
@@ -3256,6 +3257,7 @@ freebsd32_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	if (suword32(vectp++, 0) != 0)
 		return (EFAULT);
 
+	imgp->envv = vectp;
 	if (suword32(&arginfo->ps_envstr, (u_int32_t)(intptr_t)vectp) != 0 ||
 	    suword32(&arginfo->ps_nenvstr, envc) != 0)
 		return (EFAULT);
diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index bbd5fcd5249e..3ab22ed4f03b 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -1374,6 +1374,11 @@ __elfN(freebsd_copyout_auxargs)(struct image_params *imgp, uintptr_t base)
 		AUXARGS_ENTRY(pos, AT_HWCAP2, *imgp->sysent->sv_hwcap2);
 	AUXARGS_ENTRY(pos, AT_BSDFLAGS, __elfN(sigfastblock) ?
 	    ELF_BSDF_SIGFASTBLK : 0);
+	AUXARGS_ENTRY(pos, AT_ARGC, imgp->args->argc);
+	AUXARGS_ENTRY_PTR(pos, AT_ARGV, imgp->argv);
+	AUXARGS_ENTRY(pos, AT_ENVC, imgp->args->envc);
+	AUXARGS_ENTRY_PTR(pos, AT_ENVV, imgp->envv);
+	AUXARGS_ENTRY_PTR(pos, AT_PS_STRINGS, imgp->ps_strings);
 	AUXARGS_ENTRY(pos, AT_NULL, 0);
 
 	free(imgp->auxargs, M_TEMP);
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index c99bd884668d..197ca3bc9dcb 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -1646,6 +1646,7 @@ exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	/*
 	 * Fill in "ps_strings" struct for ps, w, etc.
 	 */
+	imgp->argv = vectp;
 	if (suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp) != 0 ||
 	    suword32(&arginfo->ps_nargvstr, argc) != 0)
 		return (EFAULT);
@@ -1665,6 +1666,7 @@ exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	if (suword(vectp++, 0) != 0)
 		return (EFAULT);
 
+	imgp->envv = vectp;
 	if (suword(&arginfo->ps_envstr, (long)(intptr_t)vectp) != 0 ||
 	    suword32(&arginfo->ps_nenvstr, envc) != 0)
 		return (EFAULT);
diff --git a/sys/sys/elf_common.h b/sys/sys/elf_common.h
index 41bc89be6cf7..d6b0f71adbd9 100644
--- a/sys/sys/elf_common.h
+++ b/sys/sys/elf_common.h
@@ -956,8 +956,13 @@ typedef struct {
 #define	AT_HWCAP	25	/* CPU feature flags. */
 #define	AT_HWCAP2	26	/* CPU feature flags 2. */
 #define	AT_BSDFLAGS	27	/* ELF BSD Flags. */
+#define	AT_ARGC		28	/* Argument count */
+#define	AT_ARGV		29	/* Argument vector */
+#define	AT_ENVC		30	/* Environment count */
+#define	AT_ENVV		31	/* Environment vector */
+#define	AT_PS_STRINGS	32	/* struct ps_strings */
 
-#define	AT_COUNT	28	/* Count of defined aux entry types. */
+#define	AT_COUNT	33	/* Count of defined aux entry types. */
 
 /*
  * Relocation types.
diff --git a/sys/sys/imgact.h b/sys/sys/imgact.h
index 35ddbbd946f3..b29200143189 100644
--- a/sys/sys/imgact.h
+++ b/sys/sys/imgact.h
@@ -78,6 +78,8 @@ struct image_params {
 	void *ps_strings;		/* pointer to ps_string (user space) */
 	struct image_args *args;	/* system call arguments */
 	struct sysentvec *sysent;	/* system entry vector */
+	void *argv;			/* pointer to argv (user space) */
+	void *envv;			/* pointer to envv (user space) */
 	char *execpath;
 	unsigned long execpathp;
 	char *freepath;