Avoid two suword() calls per auxarg entry.

Instead, construct an auxargs array and copy it out all at once.

Use an array of Elf_Auxinfo rather than pairs of Elf_Addr * to represent
the array. This is the correct type where pairs of words just happend
to work. To reduce the size of the diff, AUXARGS_ENTRY is altered to act
on this array rather than introducing a new macro.

Return errors on copyout() and suword() failures and handle them in the
caller.

Incidentally fixes AT_RANDOM and AT_EXECFN in 32-bit linux on amd64
which incorrectly used AUXARG_ENTRY instead of AUXARGS_ENTRY_32
(now removed due to the use of proper types).

Reviewed by:	kib
Comments from:	emaste, jhb
Obtained from:	CheriBSD
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D15485

1 files changed, 34 insertions, 30 deletions

diff --git a/sys/amd64/linux32/linux32_sysvec.c b/sys/amd64/linux32/linux32_sysvec.c
index c8d922a207f6..aedf0c5dec98 100644
--- a/sys/amd64/linux32/linux32_sysvec.c
+++ b/sys/amd64/linux32/linux32_sysvec.c
@@ -89,12 +89,6 @@ __FBSDID("$FreeBSD$");
 
 MODULE_VERSION(linux, 1);
 
-#define	AUXARGS_ENTRY_32(pos, id, val)	\
-	do {				\
-		suword32(pos++, id);	\
-		suword32(pos++, val);	\
-	} while (0)
-
 /*
  * Allow the sendsig functions to use the ldebug() facility even though they
  * are not syscalls themselves.  Map them to syscall 0.  This is slightly less
@@ -202,10 +196,10 @@ static int
 linux_fixup_elf(register_t **stack_base, struct image_params *imgp)
 {
 	Elf32_Auxargs *args;
-	Elf32_Addr *base;
-	Elf32_Addr *pos;
+	Elf32_Auxinfo *argarray, *pos;
+	Elf32_Addr *auxbase, *base;
 	struct linux32_ps_strings *arginfo;
-	int issetugid;
+	int error, issetugid;
 
 	arginfo = (struct linux32_ps_strings *)LINUX32_PS_STRINGS;
 
@@ -213,13 +207,15 @@ linux_fixup_elf(register_t **stack_base, struct image_params *imgp)
 	    ("unsafe linux_fixup_elf(), should be curproc"));
 	base = (Elf32_Addr *)*stack_base;
 	args = (Elf32_Auxargs *)imgp->auxargs;
-	pos = base + (imgp->args->argc + imgp->args->envc + 2);
+	auxbase = base + (imgp->args->argc + 1 + imgp->args->envc + 1);
+	argarray = pos = malloc(LINUX_AT_COUNT * sizeof(*pos), M_TEMP,
+	    M_WAITOK | M_ZERO);
 
 	issetugid = imgp->proc->p_flag & P_SUGID ? 1 : 0;
-	AUXARGS_ENTRY_32(pos, LINUX_AT_SYSINFO_EHDR,
+	AUXARGS_ENTRY(pos, LINUX_AT_SYSINFO_EHDR,
 	    imgp->proc->p_sysent->sv_shared_page_base);
-	AUXARGS_ENTRY_32(pos, LINUX_AT_SYSINFO, linux32_vsyscall);
-	AUXARGS_ENTRY_32(pos, LINUX_AT_HWCAP, cpu_feature);
+	AUXARGS_ENTRY(pos, LINUX_AT_SYSINFO, linux32_vsyscall);
+	AUXARGS_ENTRY(pos, LINUX_AT_HWCAP, cpu_feature);
 
 	/*
 	 * Do not export AT_CLKTCK when emulating Linux kernel prior to 2.4.0,
@@ -230,32 +226,40 @@ linux_fixup_elf(register_t **stack_base, struct image_params *imgp)
 	 * Also see linux_times() implementation.
 	 */
 	if (linux_kernver(curthread) >= LINUX_KERNVER_2004000)
-		AUXARGS_ENTRY_32(pos, LINUX_AT_CLKTCK, stclohz);
-	AUXARGS_ENTRY_32(pos, AT_PHDR, args->phdr);
-	AUXARGS_ENTRY_32(pos, AT_PHENT, args->phent);
-	AUXARGS_ENTRY_32(pos, AT_PHNUM, args->phnum);
-	AUXARGS_ENTRY_32(pos, AT_PAGESZ, args->pagesz);
-	AUXARGS_ENTRY_32(pos, AT_FLAGS, args->flags);
-	AUXARGS_ENTRY_32(pos, AT_ENTRY, args->entry);
-	AUXARGS_ENTRY_32(pos, AT_BASE, args->base);
-	AUXARGS_ENTRY_32(pos, LINUX_AT_SECURE, issetugid);
-	AUXARGS_ENTRY_32(pos, AT_UID, imgp->proc->p_ucred->cr_ruid);
-	AUXARGS_ENTRY_32(pos, AT_EUID, imgp->proc->p_ucred->cr_svuid);
-	AUXARGS_ENTRY_32(pos, AT_GID, imgp->proc->p_ucred->cr_rgid);
-	AUXARGS_ENTRY_32(pos, AT_EGID, imgp->proc->p_ucred->cr_svgid);
-	AUXARGS_ENTRY_32(pos, LINUX_AT_PLATFORM, PTROUT(linux_platform));
+		AUXARGS_ENTRY(pos, LINUX_AT_CLKTCK, stclohz);
+	AUXARGS_ENTRY(pos, AT_PHDR, args->phdr);
+	AUXARGS_ENTRY(pos, AT_PHENT, args->phent);
+	AUXARGS_ENTRY(pos, AT_PHNUM, args->phnum);
+	AUXARGS_ENTRY(pos, AT_PAGESZ, args->pagesz);
+	AUXARGS_ENTRY(pos, AT_FLAGS, args->flags);
+	AUXARGS_ENTRY(pos, AT_ENTRY, args->entry);
+	AUXARGS_ENTRY(pos, AT_BASE, args->base);
+	AUXARGS_ENTRY(pos, LINUX_AT_SECURE, issetugid);
+	AUXARGS_ENTRY(pos, AT_UID, imgp->proc->p_ucred->cr_ruid);
+	AUXARGS_ENTRY(pos, AT_EUID, imgp->proc->p_ucred->cr_svuid);
+	AUXARGS_ENTRY(pos, AT_GID, imgp->proc->p_ucred->cr_rgid);
+	AUXARGS_ENTRY(pos, AT_EGID, imgp->proc->p_ucred->cr_svgid);
+	AUXARGS_ENTRY(pos, LINUX_AT_PLATFORM, PTROUT(linux_platform));
 	AUXARGS_ENTRY(pos, LINUX_AT_RANDOM, PTROUT(imgp->canary));
 	if (imgp->execpathp != 0)
 		AUXARGS_ENTRY(pos, LINUX_AT_EXECFN, PTROUT(imgp->execpathp));
 	if (args->execfd != -1)
-		AUXARGS_ENTRY_32(pos, AT_EXECFD, args->execfd);
-	AUXARGS_ENTRY_32(pos, AT_NULL, 0);
+		AUXARGS_ENTRY(pos, AT_EXECFD, args->execfd);
+	AUXARGS_ENTRY(pos, AT_NULL, 0);
 
 	free(imgp->auxargs, M_TEMP);
 	imgp->auxargs = NULL;
+	KASSERT((pos - argarray) / sizeof(*pos) <= AT_COUNT,
+	    ("Too many auxargs"));
+
+	error = copyout(&argarray[0], auxbase, sizeof(*argarray) * AT_COUNT);
+	free(argarray, M_TEMP);
+	if (error != 0)
+		return (error);
 
 	base--;
-	suword32(base, (uint32_t)imgp->args->argc);
+	if (suword32(base, (uint32_t)imgp->args->argc) == -1)
+		return (EFAULT);
 	*stack_base = (register_t *)base;
 	return (0);
 }