git: 758d98debec4 - main - exec: Remove the stack gap implementation
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Date: Mon, 17 Jan 2022 21:13:08 UTC
The branch main has been updated by markj:
URL: https://cgit.FreeBSD.org/src/commit/?id=758d98debec43ff83b8a1ed9a3d3a8441b83b3cc
commit 758d98debec43ff83b8a1ed9a3d3a8441b83b3cc
Author: Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2022-01-17 16:42:46 +0000
Commit: Mark Johnston <markj@FreeBSD.org>
CommitDate: 2022-01-17 21:11:54 +0000
exec: Remove the stack gap implementation
ASLR stack randomization will reappear in a forthcoming commit. Rather
than inserting a random gap into the stack mapping, the entire stack
mapping itself will be randomized in the same way that other mappings
are when ASLR is enabled.
No functional change intended, as the stack gap implementation is
currently disabled by default.
Reviewed by: kib
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D33704
---
contrib/elftoolchain/readelf/readelf.c | 1 -
sys/amd64/amd64/elf_machdep.c | 2 --
sys/arm64/arm64/elf_machdep.c | 1 -
sys/compat/freebsd32/freebsd32_misc.c | 2 --
sys/compat/ia32/ia32_sysvec.c | 1 -
sys/kern/imgact_elf.c | 19 -------------------
sys/kern/kern_exec.c | 20 --------------------
sys/sys/elf_common.h | 2 +-
sys/sys/imgact.h | 2 --
sys/sys/imgact_elf.h | 1 -
sys/sys/sysent.h | 1 -
usr.bin/elfctl/elfctl.c | 2 --
12 files changed, 1 insertion(+), 53 deletions(-)
diff --git a/contrib/elftoolchain/readelf/readelf.c b/contrib/elftoolchain/readelf/readelf.c
index 987a2ffb128b..84855038d0ef 100644
--- a/contrib/elftoolchain/readelf/readelf.c
+++ b/contrib/elftoolchain/readelf/readelf.c
@@ -3755,7 +3755,6 @@ static struct flag_desc note_feature_ctl_flags[] = {
{ NT_FREEBSD_FCTL_STKGAP_DISABLE, "STKGAP_DISABLE" },
{ NT_FREEBSD_FCTL_WXNEEDED, "WXNEEDED" },
{ NT_FREEBSD_FCTL_LA48, "LA48" },
- { NT_FREEBSD_FCTL_ASG_DISABLE, "ASG_DISABLE" },
{ 0, NULL }
};
diff --git a/sys/amd64/amd64/elf_machdep.c b/sys/amd64/amd64/elf_machdep.c
index 645b9c08ea38..192a73e0a7df 100644
--- a/sys/amd64/amd64/elf_machdep.c
+++ b/sys/amd64/amd64/elf_machdep.c
@@ -92,7 +92,6 @@ struct sysentvec elf64_freebsd_sysvec_la48 = {
.sv_schedtail = NULL,
.sv_thread_detach = NULL,
.sv_trap = NULL,
- .sv_stackgap = elf64_stackgap,
.sv_onexec_old = exec_onexec_old,
.sv_onexit = exit_onexit,
.sv_set_fork_retval = x86_set_fork_retval,
@@ -135,7 +134,6 @@ struct sysentvec elf64_freebsd_sysvec_la57 = {
.sv_schedtail = NULL,
.sv_thread_detach = NULL,
.sv_trap = NULL,
- .sv_stackgap = elf64_stackgap,
.sv_onexec_old = exec_onexec_old,
.sv_onexit = exit_onexit,
.sv_set_fork_retval= x86_set_fork_retval,
diff --git a/sys/arm64/arm64/elf_machdep.c b/sys/arm64/arm64/elf_machdep.c
index 09cd72b864c2..3de0f82839e6 100644
--- a/sys/arm64/arm64/elf_machdep.c
+++ b/sys/arm64/arm64/elf_machdep.c
@@ -94,7 +94,6 @@ static struct sysentvec elf64_freebsd_sysvec = {
.sv_schedtail = NULL,
.sv_thread_detach = NULL,
.sv_trap = NULL,
- .sv_stackgap = elf64_stackgap,
.sv_hwcap = &elf_hwcap,
.sv_hwcap2 = &elf_hwcap2,
.sv_onexec_old = exec_onexec_old,
diff --git a/sys/compat/freebsd32/freebsd32_misc.c b/sys/compat/freebsd32/freebsd32_misc.c
index cc191d7ba753..60f46ad2cfba 100644
--- a/sys/compat/freebsd32/freebsd32_misc.c
+++ b/sys/compat/freebsd32/freebsd32_misc.c
@@ -3464,8 +3464,6 @@ freebsd32_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
destp = rounddown2(destp, sizeof(uint32_t));
ustringp = destp;
- exec_stackgap(imgp, &destp);
-
if (imgp->auxargs) {
/*
* Allocate room on the stack for the ELF auxargs
diff --git a/sys/compat/ia32/ia32_sysvec.c b/sys/compat/ia32/ia32_sysvec.c
index 7364a51a24af..540c2ef6fdaf 100644
--- a/sys/compat/ia32/ia32_sysvec.c
+++ b/sys/compat/ia32/ia32_sysvec.c
@@ -138,7 +138,6 @@ struct sysentvec ia32_freebsd_sysvec = {
.sv_schedtail = NULL,
.sv_thread_detach = NULL,
.sv_trap = NULL,
- .sv_stackgap = elf32_stackgap,
.sv_onexec_old = exec_onexec_old,
.sv_onexit = exit_onexit,
.sv_set_fork_retval = x86_set_fork_retval,
diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index 8852b47681f3..c3d19064f6e5 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -2757,22 +2757,3 @@ __elfN(untrans_prot)(vm_prot_t prot)
flags |= PF_W;
return (flags);
}
-
-vm_size_t
-__elfN(stackgap)(struct image_params *imgp, uintptr_t *stack_base)
-{
- uintptr_t range, rbase, gap;
- int pct;
-
- pct = __elfN(aslr_stack_gap);
- if (pct == 0)
- return (0);
- if (pct > 50)
- pct = 50;
- range = imgp->eff_stack_sz * pct / 100;
- arc4rand(&rbase, sizeof(rbase), 0);
- gap = rbase % range;
- gap &= ~(sizeof(u_long) - 1);
- *stack_base -= gap;
- return (gap);
-}
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index ee0209c6afae..09d2461e4053 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -1200,9 +1200,6 @@ exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv)
} else {
ssiz = maxssiz;
}
- imgp->eff_stack_sz = lim_cur(curthread, RLIMIT_STACK);
- if (ssiz < imgp->eff_stack_sz)
- imgp->eff_stack_sz = ssiz;
stack_addr = sv->sv_usrstack - ssiz;
stack_prot = obj != NULL && imgp->stack_prot != 0 ?
imgp->stack_prot : sv->sv_stackprot;
@@ -1557,21 +1554,6 @@ exec_args_get_begin_envv(struct image_args *args)
return (args->endp);
}
-void
-exec_stackgap(struct image_params *imgp, uintptr_t *dp)
-{
- struct proc *p = imgp->proc;
-
- if (imgp->sysent->sv_stackgap == NULL ||
- (p->p_fctl0 & (NT_FREEBSD_FCTL_ASLR_DISABLE |
- NT_FREEBSD_FCTL_ASG_DISABLE)) != 0 ||
- (imgp->map_flags & MAP_ASLR) == 0) {
- p->p_vmspace->vm_stkgap = 0;
- return;
- }
- p->p_vmspace->vm_stkgap = imgp->sysent->sv_stackgap(imgp, dp);
-}
-
/*
* Copy strings out to the new process address space, constructing new arg
* and env vector tables. Return a pointer to the base so that it can be used
@@ -1651,8 +1633,6 @@ exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
destp = rounddown2(destp, sizeof(void *));
ustringp = destp;
- exec_stackgap(imgp, &destp);
-
if (imgp->auxargs) {
/*
* Allocate room on the stack for the ELF auxargs
diff --git a/sys/sys/elf_common.h b/sys/sys/elf_common.h
index de09a2172f81..b8629fec8cbc 100644
--- a/sys/sys/elf_common.h
+++ b/sys/sys/elf_common.h
@@ -804,7 +804,7 @@ typedef struct {
#define NT_FREEBSD_FCTL_STKGAP_DISABLE 0x00000004
#define NT_FREEBSD_FCTL_WXNEEDED 0x00000008
#define NT_FREEBSD_FCTL_LA48 0x00000010
-#define NT_FREEBSD_FCTL_ASG_DISABLE 0x00000020 /* ASLR STACK GAP Disable */
+/* was ASG_DISABLE, do not reuse 0x00000020 */
/* Values for n_type. Used in core files. */
#define NT_PRSTATUS 1 /* Process status. */
diff --git a/sys/sys/imgact.h b/sys/sys/imgact.h
index 0e99737a84a7..70e5c2e81579 100644
--- a/sys/sys/imgact.h
+++ b/sys/sys/imgact.h
@@ -83,7 +83,6 @@ struct image_params {
int pagesizeslen;
vm_prot_t stack_prot;
u_long stack_sz;
- u_long eff_stack_sz;
struct ucred *newcred; /* new credentials if changing */
#define IMGACT_SHELL 0x1
#define IMGACT_BINMISC 0x2
@@ -119,7 +118,6 @@ void exec_setregs(struct thread *, struct image_params *, uintptr_t);
int exec_shell_imgact(struct image_params *);
int exec_copyin_args(struct image_args *, const char *, enum uio_seg,
char **, char **);
-void exec_stackgap(struct image_params *imgp, uintptr_t *dp);
int pre_execve(struct thread *td, struct vmspace **oldvmspace);
void post_execve(struct thread *td, int error, struct vmspace *oldvmspace);
#endif
diff --git a/sys/sys/imgact_elf.h b/sys/sys/imgact_elf.h
index 67b95207ec33..6890df5c1500 100644
--- a/sys/sys/imgact_elf.h
+++ b/sys/sys/imgact_elf.h
@@ -118,7 +118,6 @@ int __elfN(remove_brand_entry)(Elf_Brandinfo *entry);
int __elfN(freebsd_fixup)(uintptr_t *, struct image_params *);
int __elfN(coredump)(struct thread *, struct vnode *, off_t, int);
size_t __elfN(populate_note)(int, void *, void *, size_t, void **);
-vm_size_t __elfN(stackgap)(struct image_params *, uintptr_t *);
int __elfN(freebsd_copyout_auxargs)(struct image_params *, uintptr_t);
void __elfN(puthdr)(struct thread *, void *, size_t, int, size_t, int);
void __elfN(prepare_notes)(struct thread *, struct note_info_list *,
diff --git a/sys/sys/sysent.h b/sys/sys/sysent.h
index c401a0f5b3e1..9883870891da 100644
--- a/sys/sys/sysent.h
+++ b/sys/sys/sysent.h
@@ -120,7 +120,6 @@ struct sysentvec {
void (*sv_elf_core_prepare_notes)(struct thread *,
struct note_info_list *, size_t *);
int (*sv_imgact_try)(struct image_params *);
- vm_size_t (*sv_stackgap)(struct image_params *, uintptr_t *);
int (*sv_copyout_auxargs)(struct image_params *,
uintptr_t);
int sv_minsigstksz; /* minimum signal stack size */
diff --git a/usr.bin/elfctl/elfctl.c b/usr.bin/elfctl/elfctl.c
index ef7f915ded30..de14551f76d9 100644
--- a/usr.bin/elfctl/elfctl.c
+++ b/usr.bin/elfctl/elfctl.c
@@ -71,8 +71,6 @@ static struct ControlFeatures featurelist[] = {
{ "nostackgap", NT_FREEBSD_FCTL_STKGAP_DISABLE, "Disable stack gap" },
{ "wxneeded", NT_FREEBSD_FCTL_WXNEEDED, "Requires W+X mappings" },
{ "la48", NT_FREEBSD_FCTL_LA48, "amd64: Limit user VA to 48bit" },
- { "noaslrstkgap", NT_FREEBSD_FCTL_ASG_DISABLE,
- "Disable ASLR stack gap" },
};
static struct option long_opts[] = {