Date: Fri, 25 Dec 2020 13:47:38 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: ed52452d6e52 - MFC r368772: Add ELF flag to disable ASLR stack gap. Message-ID: <202012251347.0BPDlc8U082236@gitrepo.freebsd.org>
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The branch stable/12 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=ed52452d6e52a37409c15b13c0efca8d0b28c44e commit ed52452d6e52a37409c15b13c0efca8d0b28c44e Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2020-12-18 23:14:39 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2020-12-25 13:44:33 +0000 MFC r368772: Add ELF flag to disable ASLR stack gap. PR: 239873 (cherry picked from commit 673e2dd652156342009930cf1f7d15623e4a543a) --- sys/compat/freebsd32/freebsd32_misc.c | 3 +-- sys/kern/imgact_elf.c | 2 -- sys/kern/kern_exec.c | 14 ++++++++++++-- sys/sys/elf_common.h | 1 + sys/sys/imgact.h | 1 + usr.bin/elfctl/elfctl.c | 1 + 6 files changed, 16 insertions(+), 6 deletions(-) diff --git a/sys/compat/freebsd32/freebsd32_misc.c b/sys/compat/freebsd32/freebsd32_misc.c index 76054c8046a0..6c9ede34c1dc 100644 --- a/sys/compat/freebsd32/freebsd32_misc.c +++ b/sys/compat/freebsd32/freebsd32_misc.c @@ -3224,9 +3224,8 @@ freebsd32_copyout_strings(struct image_params *imgp) destp -= ARG_MAX - imgp->args->stringspace; destp = rounddown2(destp, sizeof(uint32_t)); + exec_stackgap(imgp, &destp); vectp = (uint32_t *)destp; - if (imgp->sysent->sv_stackgap != NULL) - imgp->sysent->sv_stackgap(imgp, (u_long *)&vectp); if (imgp->auxargs) { /* diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c index b1828591fc33..e436c34d1d1b 100644 --- a/sys/kern/imgact_elf.c +++ b/sys/kern/imgact_elf.c @@ -2757,8 +2757,6 @@ __elfN(stackgap)(struct image_params *imgp, u_long *stack_base) u_long range, rbase, gap; int pct; - if ((imgp->map_flags & MAP_ASLR) == 0) - return; pct = __elfN(aslr_stack_gap); if (pct == 0) return; diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c index cd6c231479bb..812d5e827093 100644 --- a/sys/kern/kern_exec.c +++ b/sys/kern/kern_exec.c @@ -1497,6 +1497,17 @@ exec_free_args(struct image_args *args) fdescfree_remapped(args->fdp); } +void +exec_stackgap(struct image_params *imgp, uintptr_t *dp) +{ + if (imgp->sysent->sv_stackgap == NULL || + (imgp->proc->p_fctl0 & (NT_FREEBSD_FCTL_ASLR_DISABLE | + NT_FREEBSD_FCTL_ASG_DISABLE)) != 0 || + (imgp->map_flags & MAP_ASLR) == 0) + return; + 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 @@ -1574,9 +1585,8 @@ exec_copyout_strings(struct image_params *imgp) destp -= ARG_MAX - imgp->args->stringspace; destp = rounddown2(destp, sizeof(void *)); + exec_stackgap(imgp, &destp); vectp = (char **)destp; - if (imgp->sysent->sv_stackgap != NULL) - imgp->sysent->sv_stackgap(imgp, (u_long *)&vectp); if (imgp->auxargs) { /* diff --git a/sys/sys/elf_common.h b/sys/sys/elf_common.h index b31ee6db7179..c469557a96e1 100644 --- a/sys/sys/elf_common.h +++ b/sys/sys/elf_common.h @@ -791,6 +791,7 @@ 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 */ /* 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 a89907e7b60d..44bf8a1359c9 100644 --- a/sys/sys/imgact.h +++ b/sys/sys/imgact.h @@ -110,6 +110,7 @@ int exec_copyin_args(struct image_args *, char *, enum uio_seg, char **, char **); int exec_copyin_data_fds(struct thread *, struct image_args *, const void *, size_t, const int *, size_t); +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/usr.bin/elfctl/elfctl.c b/usr.bin/elfctl/elfctl.c index ccc1c85007ce..d18d828e151c 100644 --- a/usr.bin/elfctl/elfctl.c +++ b/usr.bin/elfctl/elfctl.c @@ -70,6 +70,7 @@ static struct ControlFeatures featurelist[] = { #ifdef NT_FREEBSD_FCTL_LA48 { "la48", NT_FREEBSD_FCTL_LA48, "amd64: Limit user VA to 48bit" }, #endif + { "aslrstkgap", NT_FREEBSD_FCTL_ASG_DISABLE, "Disable ASLR stack gap" }, }; static struct option long_opts[] = {
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