diff options
| -rw-r--r-- | sys/amd64/amd64/elf_machdep.c | 1 | ||||
| -rw-r--r-- | sys/compat/freebsd32/freebsd32_misc.c | 3 | ||||
| -rw-r--r-- | sys/compat/ia32/ia32_sysvec.c | 1 | ||||
| -rw-r--r-- | sys/kern/imgact_elf.c | 27 | ||||
| -rw-r--r-- | sys/kern/kern_exec.c | 4 | ||||
| -rw-r--r-- | sys/sys/imgact.h | 1 | ||||
| -rw-r--r-- | sys/sys/imgact_elf.h | 1 | ||||
| -rw-r--r-- | sys/sys/sysent.h | 1 |
8 files changed, 39 insertions, 0 deletions
diff --git a/sys/amd64/amd64/elf_machdep.c b/sys/amd64/amd64/elf_machdep.c index 338d606158e8..5b31d111ff4c 100644 --- a/sys/amd64/amd64/elf_machdep.c +++ b/sys/amd64/amd64/elf_machdep.c @@ -82,6 +82,7 @@ struct sysentvec elf64_freebsd_sysvec = { .sv_schedtail = NULL, .sv_thread_detach = NULL, .sv_trap = NULL, + .sv_stackgap = elf64_stackgap, }; INIT_SYSENTVEC(elf64_sysvec, &elf64_freebsd_sysvec); diff --git a/sys/compat/freebsd32/freebsd32_misc.c b/sys/compat/freebsd32/freebsd32_misc.c index ce73635a94d5..522dc2c96f1b 100644 --- a/sys/compat/freebsd32/freebsd32_misc.c +++ b/sys/compat/freebsd32/freebsd32_misc.c @@ -3166,6 +3166,9 @@ freebsd32_copyout_strings(struct image_params *imgp) destp = rounddown2(destp, sizeof(uint32_t)); vectp = (uint32_t *)destp; + if (imgp->sysent->sv_stackgap != NULL) + imgp->sysent->sv_stackgap(imgp, (u_long *)&vectp); + 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 7f8019b1e210..00dad7441f0c 100644 --- a/sys/compat/ia32/ia32_sysvec.c +++ b/sys/compat/ia32/ia32_sysvec.c @@ -128,6 +128,7 @@ struct sysentvec ia32_freebsd_sysvec = { .sv_schedtail = NULL, .sv_thread_detach = NULL, .sv_trap = NULL, + .sv_stackgap = elf32_stackgap, }; INIT_SYSENTVEC(elf_ia32_sysvec, &ia32_freebsd_sysvec); diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c index 07dee10c30e4..1a41c0886430 100644 --- a/sys/kern/imgact_elf.c +++ b/sys/kern/imgact_elf.c @@ -156,6 +156,12 @@ SYSCTL_INT(ASLR_NODE_OID, OID_AUTO, honor_sbrk, CTLFLAG_RW, &__elfN(aslr_honor_sbrk), 0, __XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE)) ": assume sbrk is used"); +static int __elfN(aslr_stack_gap) = 3; +SYSCTL_INT(ASLR_NODE_OID, OID_AUTO, stack_gap, CTLFLAG_RW, + &__elfN(aslr_stack_gap), 0, + __XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE)) + ": maximum percentage of main stack to waste on a random gap"); + static Elf_Brandinfo *elf_brand_list[MAX_BRANDS]; #define aligned(a, t) (rounddown2((u_long)(a), sizeof(t)) == (u_long)(a)) @@ -2720,3 +2726,24 @@ __elfN(untrans_prot)(vm_prot_t prot) flags |= PF_W; return (flags); } + +void +__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; + if (pct > 50) + pct = 50; + range = imgp->eff_stack_sz * pct / 100; + range *= pct; + arc4rand(&rbase, sizeof(rbase), 0); + gap = rbase % range; + gap &= ~(sizeof(u_long) - 1); + *stack_base -= gap; +} diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c index d8d6d8b69b0a..50d4f8b585a4 100644 --- a/sys/kern/kern_exec.c +++ b/sys/kern/kern_exec.c @@ -1128,6 +1128,7 @@ exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv) } else { ssiz = maxssiz; } + imgp->eff_stack_sz = ssiz; stack_addr = sv->sv_usrstack - ssiz; error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : @@ -1615,6 +1616,9 @@ exec_copyout_strings(struct image_params *imgp) destp = rounddown2(destp, sizeof(void *)); vectp = (char **)destp; + if (imgp->sysent->sv_stackgap != NULL) + imgp->sysent->sv_stackgap(imgp, (u_long *)&vectp); + if (imgp->auxargs) { /* * Allocate room on the stack for the ELF auxargs diff --git a/sys/sys/imgact.h b/sys/sys/imgact.h index 167ee11c7038..25393d8194c1 100644 --- a/sys/sys/imgact.h +++ b/sys/sys/imgact.h @@ -87,6 +87,7 @@ 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 */ bool credential_setid; /* true if becoming setid */ bool textset; diff --git a/sys/sys/imgact_elf.h b/sys/sys/imgact_elf.h index 9c5acb21c9d1..8bf5c5ab3b6d 100644 --- a/sys/sys/imgact_elf.h +++ b/sys/sys/imgact_elf.h @@ -98,6 +98,7 @@ int __elfN(remove_brand_entry)(Elf_Brandinfo *entry); int __elfN(freebsd_fixup)(register_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 **); +void __elfN(stackgap)(struct image_params *, u_long *); /* Machine specific function to dump per-thread information. */ void __elfN(dump_thread)(struct thread *, void *, size_t *); diff --git a/sys/sys/sysent.h b/sys/sys/sysent.h index e13318a30cd0..e5d3d243a216 100644 --- a/sys/sys/sysent.h +++ b/sys/sys/sysent.h @@ -109,6 +109,7 @@ struct sysentvec { int (*sv_coredump)(struct thread *, struct vnode *, off_t, int); /* function to dump core, or NULL */ int (*sv_imgact_try)(struct image_params *); + void (*sv_stackgap)(struct image_params *, u_long *); int sv_minsigstksz; /* minimum signal stack size */ vm_offset_t sv_minuser; /* VM_MIN_ADDRESS */ vm_offset_t sv_maxuser; /* VM_MAXUSER_ADDRESS */ |