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[src/trunk]: src/sys Tidy up the vnode locking around execve() on ELF images ...
details: https://anonhg.NetBSD.org/src/rev/ff76e4e9b6e1
branches: trunk
changeset: 467068:ff76e4e9b6e1
user: ad <ad%NetBSD.org@localhost>
date: Sun Jan 12 18:30:58 2020 +0000
description:
Tidy up the vnode locking around execve() on ELF images to acquire and
release the locks fewer times. Proposed on tech-kern a very long time go.
diffstat:
sys/compat/linux/arch/amd64/linux_exec_machdep.c | 6 +-
sys/compat/linux/common/linux_exec_elf32.c | 43 +++++++-----
sys/kern/exec_elf.c | 78 +++++++++++++++--------
sys/kern/exec_subr.c | 14 ++-
sys/kern/kern_exec.c | 18 +++--
sys/sys/exec.h | 6 +-
6 files changed, 99 insertions(+), 66 deletions(-)
diffs (truncated from 505 to 300 lines):
diff -r c5caba7578f8 -r ff76e4e9b6e1 sys/compat/linux/arch/amd64/linux_exec_machdep.c
--- a/sys/compat/linux/arch/amd64/linux_exec_machdep.c Sun Jan 12 17:49:17 2020 +0000
+++ b/sys/compat/linux/arch/amd64/linux_exec_machdep.c Sun Jan 12 18:30:58 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: linux_exec_machdep.c,v 1.22 2014/02/23 12:01:51 njoly Exp $ */
+/* $NetBSD: linux_exec_machdep.c,v 1.23 2020/01/12 18:30:58 ad Exp $ */
/*-
* Copyright (c) 2005 Emmanuel Dreyfus, all rights reserved
@@ -32,7 +32,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_exec_machdep.c,v 1.22 2014/02/23 12:01:51 njoly Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_exec_machdep.c,v 1.23 2020/01/12 18:30:58 ad Exp $");
#define ELFSIZE 64
@@ -156,7 +156,7 @@
if (ap == NULL) {
phsize = eh->e_phnum * sizeof(Elf_Phdr);
ph = (Elf_Phdr *)kmem_alloc(phsize, KM_SLEEP);
- error = exec_read_from(l, pack->ep_vp, eh->e_phoff, ph, phsize);
+ error = exec_read(l, pack->ep_vp, eh->e_phoff, ph, phsize, 0);
if (error != 0) {
for (i = 0; i < eh->e_phnum; i++) {
if (ph[i].p_type == PT_PHDR) {
diff -r c5caba7578f8 -r ff76e4e9b6e1 sys/compat/linux/common/linux_exec_elf32.c
--- a/sys/compat/linux/common/linux_exec_elf32.c Sun Jan 12 17:49:17 2020 +0000
+++ b/sys/compat/linux/common/linux_exec_elf32.c Sun Jan 12 18:30:58 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: linux_exec_elf32.c,v 1.99 2019/03/01 11:06:56 pgoyette Exp $ */
+/* $NetBSD: linux_exec_elf32.c,v 1.100 2020/01/12 18:30:58 ad Exp $ */
/*-
* Copyright (c) 1995, 1998, 2000, 2001 The NetBSD Foundation, Inc.
@@ -35,7 +35,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_exec_elf32.c,v 1.99 2019/03/01 11:06:56 pgoyette Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_exec_elf32.c,v 1.100 2020/01/12 18:30:58 ad Exp $");
#ifndef ELFSIZE
/* XXX should die */
@@ -107,7 +107,8 @@
/* Load the section header table. */
shsize = eh->e_shnum * sizeof(Elf_Shdr);
sh = (Elf_Shdr *) malloc(shsize, M_TEMP, M_WAITOK);
- error = exec_read_from(l, epp->ep_vp, eh->e_shoff, sh, shsize);
+ error = exec_read(l, epp->ep_vp, eh->e_shoff, sh, shsize,
+ IO_NODELOCKED);
if (error)
goto out;
@@ -126,8 +127,8 @@
if (s->sh_name + sigsz > sh[shstrndx].sh_size)
continue;
- error = exec_read_from(l, epp->ep_vp, stroff + s->sh_name, tbuf,
- sigsz);
+ error = exec_read(l, epp->ep_vp, stroff + s->sh_name, tbuf,
+ sigsz, IO_NODELOCKED);
if (error)
goto out;
if (!memcmp(tbuf, signature, sigsz)) {
@@ -171,7 +172,8 @@
shsize = eh->e_shnum * sizeof(Elf_Shdr);
sh = (Elf_Shdr *) malloc(shsize, M_TEMP, M_WAITOK);
- error = exec_read_from(l, epp->ep_vp, eh->e_shoff, sh, shsize);
+ error = exec_read(l, epp->ep_vp, eh->e_shoff, sh, shsize,
+ IO_NODELOCKED);
if (error)
goto out;
@@ -189,8 +191,8 @@
s->sh_size < sizeof(signature) - 1)
continue;
- error = exec_read_from(l, epp->ep_vp, s->sh_offset, tbuf,
- sizeof(signature) - 1);
+ error = exec_read(l, epp->ep_vp, s->sh_offset, tbuf,
+ sizeof(signature) - 1, IO_NODELOCKED);
if (error)
continue;
@@ -230,7 +232,8 @@
/* Load the section header table. */
shsize = eh->e_shnum * sizeof(Elf_Shdr);
sh = (Elf_Shdr *) malloc(shsize, M_TEMP, M_WAITOK);
- error = exec_read_from(l, epp->ep_vp, eh->e_shoff, sh, shsize);
+ error = exec_read(l, epp->ep_vp, eh->e_shoff, sh, shsize,
+ IO_NODELOCKED);
if (error)
goto out;
@@ -249,8 +252,8 @@
if (s->sh_name + sigsz > sh[shstrndx].sh_size)
continue;
- error = exec_read_from(l, epp->ep_vp, stroff + s->sh_name, tbuf,
- sigsz);
+ error = exec_read(l, epp->ep_vp, stroff + s->sh_name, tbuf,
+ sigsz, IO_NODELOCKED);
if (error)
goto out;
if (!memcmp(tbuf, signature, sigsz)) {
@@ -290,7 +293,8 @@
/* Load the section header table. */
shsize = eh->e_shnum * sizeof(Elf_Shdr);
sh = malloc(shsize, M_TEMP, M_WAITOK);
- error = exec_read_from(l, epp->ep_vp, eh->e_shoff, sh, shsize);
+ error = exec_read(l, epp->ep_vp, eh->e_shoff, sh, shsize,
+ IO_NODELOCKED);
if (error)
goto out;
@@ -309,8 +313,8 @@
if (s->sh_name + sigsz > sh[shstrndx].sh_size)
continue;
- error = exec_read_from(l, epp->ep_vp, stroff + s->sh_name, tbuf,
- sigsz);
+ error = exec_read(l, epp->ep_vp, stroff + s->sh_name, tbuf,
+ sigsz, IO_NODELOCKED);
if (error)
goto out;
if (!memcmp(tbuf, signature, sigsz)) {
@@ -329,8 +333,8 @@
sh[i].sh_size = 1024 * 1024;
tmp = malloc(sh[i].sh_size, M_TEMP, M_WAITOK);
- error = exec_read_from(l, epp->ep_vp, sh[i].sh_offset, tmp,
- sh[i].sh_size);
+ error = exec_read(l, epp->ep_vp, sh[i].sh_offset, tmp,
+ sh[i].sh_size, IO_NODELOCKED);
if (error)
goto out;
@@ -368,7 +372,8 @@
phsize = eh->e_phnum * sizeof(Elf_Phdr);
ph = (Elf_Phdr *)malloc(phsize, M_TEMP, M_WAITOK);
- error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize);
+ error = exec_read(l, epp->ep_vp, eh->e_phoff, ph, phsize,
+ IO_NODELOCKED);
if (error)
goto out;
@@ -383,8 +388,8 @@
continue;
np = (Elf_Nhdr *)malloc(ephp->p_filesz, M_TEMP, M_WAITOK);
- error = exec_read_from(l, epp->ep_vp, ephp->p_offset, np,
- ephp->p_filesz);
+ error = exec_read(l, epp->ep_vp, ephp->p_offset, np,
+ ephp->p_filesz, IO_NODELOCKED);
if (error)
goto next;
diff -r c5caba7578f8 -r ff76e4e9b6e1 sys/kern/exec_elf.c
--- a/sys/kern/exec_elf.c Sun Jan 12 17:49:17 2020 +0000
+++ b/sys/kern/exec_elf.c Sun Jan 12 18:30:58 2020 +0000
@@ -1,7 +1,7 @@
-/* $NetBSD: exec_elf.c,v 1.100 2019/09/16 11:11:34 christos Exp $ */
+/* $NetBSD: exec_elf.c,v 1.101 2020/01/12 18:30:58 ad Exp $ */
/*-
- * Copyright (c) 1994, 2000, 2005, 2015 The NetBSD Foundation, Inc.
+ * Copyright (c) 1994, 2000, 2005, 2015, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@@ -57,7 +57,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.100 2019/09/16 11:11:34 christos Exp $");
+__KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.101 2020/01/12 18:30:58 ad Exp $");
#ifdef _KERNEL_OPT
#include "opt_pax.h"
@@ -330,6 +330,8 @@
long diff, offset;
int vmprot = 0;
+ KASSERT(VOP_ISLOCKED(vp) != LK_NONE);
+
/*
* If the user specified an address, then we load there.
*/
@@ -462,14 +464,15 @@
*/
if (vp->v_type != VREG) {
error = EACCES;
- goto badunlock;
+ goto bad;
}
if ((error = VOP_ACCESS(vp, VEXEC, l->l_cred)) != 0)
- goto badunlock;
+ goto bad;
/* get attributes */
+ /* XXX VOP_GETATTR() is the only thing that needs LK_EXCLUSIVE ^ */
if ((error = VOP_GETATTR(vp, &attr, l->l_cred)) != 0)
- goto badunlock;
+ goto bad;
/*
* Check mount point. Though we're not trying to exec this binary,
@@ -478,18 +481,17 @@
*/
if (vp->v_mount->mnt_flag & MNT_NOEXEC) {
error = EACCES;
- goto badunlock;
+ goto bad;
}
if (vp->v_mount->mnt_flag & MNT_NOSUID)
epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID);
error = vn_marktext(vp);
if (error)
- goto badunlock;
+ goto bad;
- VOP_UNLOCK(vp);
-
- if ((error = exec_read_from(l, vp, 0, &eh, sizeof(eh))) != 0)
+ error = exec_read(l, vp, 0, &eh, sizeof(eh), IO_NODELOCKED);
+ if (error != 0)
goto bad;
if ((error = elf_check_header(&eh)) != 0)
@@ -503,7 +505,8 @@
phsize = eh.e_phnum * sizeof(Elf_Phdr);
ph = kmem_alloc(phsize, KM_SLEEP);
- if ((error = exec_read_from(l, vp, eh.e_phoff, ph, phsize)) != 0)
+ error = exec_read(l, vp, eh.e_phoff, ph, phsize, IO_NODELOCKED);
+ if (error != 0)
goto bad;
#ifdef ELF_INTERP_NON_RELOCATABLE
@@ -629,16 +632,13 @@
* This value is ignored if TOPDOWN.
*/
*last = addr;
- vrele(vp);
+ vput(vp);
return 0;
-badunlock:
- VOP_UNLOCK(vp);
-
bad:
if (ph != NULL)
kmem_free(ph, phsize);
- vrele(vp);
+ vput(vp);
return error;
}
@@ -683,9 +683,13 @@
return ENOEXEC;
}
+ /* XXX only LK_EXCLUSIVE to match all others - allow spinning */
+ vn_lock(epp->ep_vp, LK_EXCLUSIVE | LK_RETRY);
error = vn_marktext(epp->ep_vp);
- if (error)
+ if (error) {
+ VOP_UNLOCK(epp->ep_vp);
return error;
+ }
/*
* Allocate space to hold all the program headers, and read them
@@ -694,9 +698,12 @@
phsize = eh->e_phnum * sizeof(Elf_Phdr);
ph = kmem_alloc(phsize, KM_SLEEP);
- if ((error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize)) !=
- 0)
+ error = exec_read(l, epp->ep_vp, eh->e_phoff, ph, phsize,
+ IO_NODELOCKED);
+ if (error != 0) {
+ VOP_UNLOCK(epp->ep_vp);
goto bad;
+ }
epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR);
epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR);
@@ -708,16 +715,21 @@
DPRINTF("bad interpreter namelen %#jx",
(uintmax_t)pp->p_filesz);
error = ENOEXEC;
+ VOP_UNLOCK(epp->ep_vp);
goto bad;
}
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