concurrent sysctl implementation
Kostik Belousov
kostikbel at gmail.com
Fri Jul 24 21:29:41 UTC 2009
On Fri, Jul 24, 2009 at 03:49:53PM +0200, Ed Schouten wrote:
> * Jeremie Le Hen <jeremie at le-hen.org> wrote:
> > On Fri, Jul 24, 2009 at 01:56:49PM +0200, Ed Schouten wrote:
> > > * Jeremie Le Hen <jeremie at le-hen.org> wrote:
> > > > On Fri, Jul 24, 2009 at 11:18:42AM +0300, Kostik Belousov wrote:
> > > > > On Fri, Jul 24, 2009 at 09:34:51AM +0200, Jeremie Le Hen wrote:
> > > > > > Hi Ed,
> > > > > >
> > > > > > Sorry for the late reply.
> > > > > >
> > > > > > On Sat, May 09, 2009 at 02:13:13PM +0200, Ed Schouten wrote:
> > > > > > > We probably could. I think I discussed this with Robert Watson some time
> > > > > > > ago and we could use things like ELF hints. But still, that doesn't
> > > > > > > prevent us from reaching this limitation later on.
> > > > > >
> > > > > > Can you elaborate a little? Are you talking about elf-hints.h?
> > > > > > I don't see where we can get randomness from it.
> > > > >
> > > > > The thing is called ELF auxillary information vector. It is used to
> > > > > supply some useful information for interpreter from the kernel,
> > > > > see include/machine/elf.h for AT_* entries.
> > > >
> > > > Ah ok, so the idea is to generate a new hint, for instance AT_RANDOM,
> > > > generated at link time, that will be used to fill the canary at exec(2)
> > > > time?
> > >
> > > Very short answer: yes!
> >
> > Ok thanks. But this would make stack protection useless for local
> > attacks on suid binaries that are world-readable since the attacker
> > could read the ELF aux vector and compute the canary.
>
> Wait wait wait. It seems you were only partially right (and Kostik
> corrected you):
>
> We could add AT_RANDOM, but this value will be filled in by the kernel
> when starting the process. This means the random value is not stored in
> the binary.
Below is the prototype that seems to work for me both with patched and
old rtld on i386. Patch also contains bits for amd64 that I did not
tested yet. All other arches are not buildable for now.
Patch completely eliminates sysctl syscalls from the rtld and libc
startup. Without the patch, a single run of /bin/ls did 6 sysctls,
with the patch, no sysctls is queried at all.
diff --git a/lib/libc/gen/__getosreldate.c b/lib/libc/gen/__getosreldate.c
index 69aac07..6a4e5ea 100644
--- a/lib/libc/gen/__getosreldate.c
+++ b/lib/libc/gen/__getosreldate.c
@@ -29,6 +29,8 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/sysctl.h>
+#include <errno.h>
+#include <link.h>
/*
* This is private to libc. It is intended for wrapping syscall stubs in order
@@ -49,7 +51,15 @@ __getosreldate(void)
if (osreldate != 0)
return (osreldate);
-
+
+ if (_rtld_aux_info != NULL)
+ error = _rtld_aux_info(AT_OSRELDATE, &osreldate,
+ sizeof(osreldate));
+ else
+ error = ENOSYS;
+ if (error == 0 && osreldate != 0)
+ return (osreldate);
+
oid[0] = CTL_KERN;
oid[1] = KERN_OSRELDATE;
osrel = 0;
diff --git a/lib/libc/gen/getpagesize.c b/lib/libc/gen/getpagesize.c
index d796b9d..b8f0ec1 100644
--- a/lib/libc/gen/getpagesize.c
+++ b/lib/libc/gen/getpagesize.c
@@ -36,6 +36,8 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/sysctl.h>
+#include <errno.h>
+#include <link.h>
#include <unistd.h>
/*
@@ -52,13 +54,23 @@ getpagesize()
int mib[2];
static int value;
size_t size;
+ int error;
+
+ if (value != 0)
+ return (value);
+
+ if (_rtld_aux_info != NULL)
+ error = _rtld_aux_info(AT_PAGESZ, &value, sizeof(value));
+ else
+ error = ENOSYS;
+ if (error == 0 && value != 0)
+ return (value);
+
+ mib[0] = CTL_HW;
+ mib[1] = HW_PAGESIZE;
+ size = sizeof value;
+ if (sysctl(mib, 2, &value, &size, NULL, 0) == -1)
+ return (-1);
- if (!value) {
- mib[0] = CTL_HW;
- mib[1] = HW_PAGESIZE;
- size = sizeof value;
- if (sysctl(mib, 2, &value, &size, NULL, 0) == -1)
- return (-1);
- }
return (value);
}
diff --git a/lib/libc/stdlib/malloc.c b/lib/libc/stdlib/malloc.c
index 270d641..e479abe 100644
--- a/lib/libc/stdlib/malloc.c
+++ b/lib/libc/stdlib/malloc.c
@@ -179,6 +179,7 @@ __FBSDID("$FreeBSD$");
#include <errno.h>
#include <limits.h>
+#include <link.h>
#include <pthread.h>
#include <sched.h>
#include <stdarg.h>
@@ -4769,7 +4770,10 @@ malloc_init_hard(void)
unsigned i;
int linklen;
char buf[PATH_MAX + 1];
+ int mib[2];
+ size_t len;
const char *opts;
+ int error;
malloc_mutex_lock(&init_lock);
if (malloc_initialized) {
@@ -4782,10 +4786,11 @@ malloc_init_hard(void)
}
/* Get number of CPUs. */
- {
- int mib[2];
- size_t len;
-
+ if (_rtld_aux_info != NULL)
+ error = _rtld_aux_info(AT_NCPUS, &ncpus, sizeof(ncpus));
+ else
+ error = ENOSYS;
+ if (error != 0 || ncpus == 0) {
mib[0] = CTL_HW;
mib[1] = HW_NCPU;
len = sizeof(ncpus);
diff --git a/lib/libc/sys/stack_protector.c b/lib/libc/sys/stack_protector.c
index 63beebc..571f63c 100644
--- a/lib/libc/sys/stack_protector.c
+++ b/lib/libc/sys/stack_protector.c
@@ -34,6 +34,8 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/sysctl.h>
#include <sys/types.h>
+#include <errno.h>
+#include <link.h>
#include <signal.h>
#include <string.h>
#include <syslog.h>
@@ -54,9 +56,17 @@ __guard_setup(void)
{
int mib[2];
size_t len;
+ int error;
if (__stack_chk_guard[0] != 0)
return;
+ if (_rtld_aux_info != NULL)
+ error = _rtld_aux_info(AT_CANARY, __stack_chk_guard,
+ sizeof(__stack_chk_guard));
+ else
+ error = ENOSYS;
+ if (error == 0 && __stack_chk_guard[0] != 0)
+ return;
mib[0] = CTL_KERN;
mib[1] = KERN_ARND;
diff --git a/libexec/rtld-elf/Symbol.map b/libexec/rtld-elf/Symbol.map
index ce1e3e5..f45f955 100644
--- a/libexec/rtld-elf/Symbol.map
+++ b/libexec/rtld-elf/Symbol.map
@@ -24,4 +24,5 @@ FBSDprivate_1.0 {
_rtld_free_tls;
_rtld_atfork_pre;
_rtld_atfork_post;
+ _rtld_aux_info;
};
diff --git a/libexec/rtld-elf/amd64/reloc.c b/libexec/rtld-elf/amd64/reloc.c
index 8a32adf..a510884 100644
--- a/libexec/rtld-elf/amd64/reloc.c
+++ b/libexec/rtld-elf/amd64/reloc.c
@@ -113,7 +113,7 @@ init_pltgot(Obj_Entry *obj)
/* Process the non-PLT relocations. */
int
-reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
+reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, bool early)
{
const Elf_Rela *relalim;
const Elf_Rela *rela;
@@ -125,9 +125,13 @@ reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
* The dynamic loader may be called from a thread, we have
* limited amounts of stack available so we cannot use alloca().
*/
- cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
- if (cache == MAP_FAILED)
+ if (early)
cache = NULL;
+ else {
+ cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
+ if (cache == MAP_FAILED)
+ cache = NULL;
+ }
relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize);
for (rela = obj->rela; rela < relalim; rela++) {
diff --git a/libexec/rtld-elf/i386/reloc.c b/libexec/rtld-elf/i386/reloc.c
index ec83bff..2913d78 100644
--- a/libexec/rtld-elf/i386/reloc.c
+++ b/libexec/rtld-elf/i386/reloc.c
@@ -114,7 +114,7 @@ init_pltgot(Obj_Entry *obj)
/* Process the non-PLT relocations. */
int
-reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
+reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, bool early)
{
const Elf_Rel *rellim;
const Elf_Rel *rel;
@@ -126,9 +126,13 @@ reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
* The dynamic loader may be called from a thread, we have
* limited amounts of stack available so we cannot use alloca().
*/
- cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
- if (cache == MAP_FAILED)
+ if (early)
cache = NULL;
+ else {
+ cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
+ if (cache == MAP_FAILED)
+ cache = NULL;
+ }
rellim = (const Elf_Rel *) ((caddr_t) obj->rel + obj->relsize);
for (rel = obj->rel; rel < rellim; rel++) {
diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 721fe89..75a1c69 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -40,6 +40,7 @@
#include <sys/mount.h>
#include <sys/mman.h>
#include <sys/stat.h>
+#include <sys/sysctl.h>
#include <sys/uio.h>
#include <sys/utsname.h>
#include <sys/ktrace.h>
@@ -84,6 +85,9 @@ typedef struct Struct_DoneList {
*/
static const char *basename(const char *);
static void die(void) __dead2;
+static void digest_dynamic1(Obj_Entry *, int, const Elf_Dyn **,
+ const Elf_Dyn **);
+static void digest_dynamic2(Obj_Entry *, const Elf_Dyn *, const Elf_Dyn *);
static void digest_dynamic(Obj_Entry *, int);
static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
static Obj_Entry *dlcheck(void *);
@@ -97,7 +101,7 @@ static char *find_library(const char *, const Obj_Entry *);
static const char *gethints(void);
static void init_dag(Obj_Entry *);
static void init_dag1(Obj_Entry *, Obj_Entry *, DoneList *);
-static void init_rtld(caddr_t);
+static void init_rtld(caddr_t, Elf_Auxinfo **);
static void initlist_add_neededs(Needed_Entry *, Objlist *);
static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *);
static bool is_exported(const Elf_Sym *);
@@ -116,7 +120,7 @@ static void objlist_push_head(Objlist *, Obj_Entry *);
static void objlist_push_tail(Objlist *, Obj_Entry *);
static void objlist_remove(Objlist *, Obj_Entry *);
static void *path_enumerate(const char *, path_enum_proc, void *);
-static int relocate_objects(Obj_Entry *, bool, Obj_Entry *);
+static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, bool early);
static int rtld_dirname(const char *, char *);
static int rtld_dirname_abs(const char *, char *);
static void rtld_exit(void);
@@ -188,6 +192,9 @@ extern Elf_Dyn _DYNAMIC;
#define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL)
#endif
+static int pagesize, osreldate, canary_len, ncpus;
+static char *canary;
+
/*
* These are the functions the dynamic linker exports to application
* programs. They are the only symbols the dynamic linker is willing
@@ -214,6 +221,7 @@ static func_ptr_type exports[] = {
(func_ptr_type) &dl_iterate_phdr,
(func_ptr_type) &_rtld_atfork_pre,
(func_ptr_type) &_rtld_atfork_post,
+ (func_ptr_type) &_rtld_aux_info,
NULL
};
@@ -350,7 +358,7 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
/* Initialize and relocate ourselves. */
assert(aux_info[AT_BASE] != NULL);
- init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
+ init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr, aux_info);
__progname = obj_rtld.path;
argv0 = argv[0] != NULL ? argv[0] : "(null)";
@@ -519,7 +527,7 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
allocate_initial_tls(obj_list);
if (relocate_objects(obj_main,
- ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1)
+ ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld, false) == -1)
die();
dbg("doing copy relocations");
@@ -736,14 +744,16 @@ die(void)
* information in its Obj_Entry structure.
*/
static void
-digest_dynamic(Obj_Entry *obj, int early)
+digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
+ const Elf_Dyn **dyn_soname)
{
const Elf_Dyn *dynp;
Needed_Entry **needed_tail = &obj->needed;
- const Elf_Dyn *dyn_rpath = NULL;
- const Elf_Dyn *dyn_soname = NULL;
int plttype = DT_REL;
+ *dyn_rpath = NULL;
+ *dyn_soname = NULL;
+
obj->bind_now = false;
for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
switch (dynp->d_tag) {
@@ -867,11 +877,11 @@ digest_dynamic(Obj_Entry *obj, int early)
* We have to wait until later to process this, because we
* might not have gotten the address of the string table yet.
*/
- dyn_rpath = dynp;
+ *dyn_rpath = dynp;
break;
case DT_SONAME:
- dyn_soname = dynp;
+ *dyn_soname = dynp;
break;
case DT_INIT:
@@ -958,6 +968,12 @@ digest_dynamic(Obj_Entry *obj, int early)
obj->pltrelasize = obj->pltrelsize;
obj->pltrelsize = 0;
}
+}
+
+static void
+digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath,
+ const Elf_Dyn *dyn_soname)
+{
if (obj->z_origin && obj->origin_path == NULL) {
obj->origin_path = xmalloc(PATH_MAX);
@@ -975,6 +991,16 @@ digest_dynamic(Obj_Entry *obj, int early)
object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
}
+static void
+digest_dynamic(Obj_Entry *obj, int early)
+{
+ const Elf_Dyn *dyn_rpath;
+ const Elf_Dyn *dyn_soname;
+
+ digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname);
+ digest_dynamic2(obj, dyn_rpath, dyn_soname);
+}
+
/*
* Process a shared object's program header. This is used only for the
* main program, when the kernel has already loaded the main program
@@ -1301,9 +1327,11 @@ init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp)
* this function is to relocate the dynamic linker.
*/
static void
-init_rtld(caddr_t mapbase)
+init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info)
{
Obj_Entry objtmp; /* Temporary rtld object */
+ const Elf_Dyn *dyn_rpath;
+ const Elf_Dyn *dyn_soname;
/*
* Conjure up an Obj_Entry structure for the dynamic linker.
@@ -1320,27 +1348,38 @@ init_rtld(caddr_t mapbase)
#endif
if (RTLD_IS_DYNAMIC()) {
objtmp.dynamic = rtld_dynamic(&objtmp);
- digest_dynamic(&objtmp, 1);
+ digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname);
assert(objtmp.needed == NULL);
#if !defined(__mips__)
/* MIPS and SH{3,5} have a bogus DT_TEXTREL. */
assert(!objtmp.textrel);
#endif
-
/*
* Temporarily put the dynamic linker entry into the object list, so
* that symbols can be found.
*/
- relocate_objects(&objtmp, true, &objtmp);
+ relocate_objects(&objtmp, true, &objtmp, true);
}
-
/* Initialize the object list. */
obj_tail = &obj_list;
/* Now that non-local variables can be accesses, copy out obj_rtld. */
memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
+ if (aux_info[AT_PAGESZ] != NULL)
+ pagesize = aux_info[AT_PAGESZ]->a_un.a_val;
+ if (aux_info[AT_OSRELDATE] != NULL)
+ osreldate = aux_info[AT_OSRELDATE]->a_un.a_val;
+ if (aux_info[AT_CANARY] != NULL && aux_info[AT_CANARYLEN] != NULL) {
+ canary = aux_info[AT_CANARY]->a_un.a_ptr;
+ canary_len = aux_info[AT_CANARYLEN]->a_un.a_val;
+ }
+ if (aux_info[AT_NCPUS] != NULL)
+ ncpus = aux_info[AT_NCPUS]->a_un.a_val;
+
+ digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname);
+
/* Replace the path with a dynamically allocated copy. */
obj_rtld.path = xstrdup(PATH_RTLD);
@@ -1745,7 +1784,8 @@ objlist_remove(Objlist *list, Obj_Entry *obj)
* or -1 on failure.
*/
static int
-relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj)
+relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
+ bool early)
{
Obj_Entry *obj;
@@ -1770,7 +1810,7 @@ relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj)
}
/* Process the non-PLT relocations. */
- if (reloc_non_plt(obj, rtldobj))
+ if (reloc_non_plt(obj, rtldobj, early))
return -1;
if (obj->textrel) { /* Re-protected the text segment. */
@@ -2022,7 +2062,8 @@ dlopen(const char *name, int mode)
if (result != -1 && ld_tracing)
goto trace;
if (result == -1 ||
- (relocate_objects(obj, mode == RTLD_NOW, &obj_rtld)) == -1) {
+ (relocate_objects(obj, mode == RTLD_NOW, &obj_rtld, false))
+ == -1) {
obj->dl_refcount--;
unref_dag(obj);
if (obj->refcount == 0)
@@ -3611,3 +3652,110 @@ fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
}
return NULL;
}
+
+static int
+__getosreldate(void)
+{
+ static int osreldate;
+ size_t len;
+ int oid[2];
+ int error, osrel;
+
+ oid[0] = CTL_KERN;
+ oid[1] = KERN_OSRELDATE;
+ osrel = 0;
+ len = sizeof(osrel);
+ error = sysctl(oid, 2, &osrel, &len, NULL, 0);
+ if (error == 0 && osrel > 0 && len == sizeof(osrel))
+ osreldate = osrel;
+ return (osreldate);
+}
+
+static int
+__getpagesize(void)
+{
+ int mib[2];
+ static int value;
+ size_t size;
+
+ mib[0] = CTL_HW;
+ mib[1] = HW_PAGESIZE;
+ size = sizeof value;
+ if (sysctl(mib, 2, &value, &size, NULL, 0) == -1)
+ return (-1);
+
+ return (value);
+}
+
+static int
+__getncpus(void)
+{
+ int mib[2];
+ size_t len;
+ int n;
+
+ mib[0] = CTL_HW;
+ mib[1] = HW_NCPU;
+ len = sizeof(ncpus);
+ if (sysctl(mib, 2, &n, &len, (void *) 0, 0) == -1)
+ n = 1;
+ return (n);
+}
+
+int
+_rtld_aux_info(int aux, void *buf, int buflen)
+{
+ int res;
+
+ switch (aux) {
+ case AT_CANARY:
+ if (canary != NULL && canary_len >= buflen) {
+ memcpy(buf, canary, buflen);
+ memset(canary, 0, canary_len);
+ canary = NULL;
+ res = 0;
+ } else
+ res = ENOENT;
+ break;
+ case AT_PAGESZ:
+ if (buflen == sizeof(int)) {
+ if (pagesize == 0)
+ pagesize = __getpagesize();
+ if (pagesize != 0) {
+ *(int *)buf = pagesize;
+ res = 0;
+ } else
+ res = ENOENT;
+ } else
+ res = EINVAL;
+ break;
+ case AT_OSRELDATE:
+ if (buflen == sizeof(int)) {
+ if (osreldate == 0)
+ osreldate = __getosreldate();
+ if (osreldate != 0) {
+ *(int *)buf = osreldate;
+ res = 0;
+ } else
+ res = ENOENT;
+ } else
+ res = EINVAL;
+ break;
+ case AT_NCPUS:
+ if (buflen == sizeof(int)) {
+ if (ncpus == 0)
+ ncpus = __getncpus();
+ if (ncpus != 0) {
+ *(int *)buf = ncpus;
+ res = 0;
+ } else
+ res = ENOENT;
+ } else
+ res = EINVAL;
+ break;
+ default:
+ res = ENOENT;
+ break;
+ }
+ return (res);
+}
diff --git a/libexec/rtld-elf/rtld.h b/libexec/rtld-elf/rtld.h
index 06086b4..928e3ed 100644
--- a/libexec/rtld-elf/rtld.h
+++ b/libexec/rtld-elf/rtld.h
@@ -286,7 +286,7 @@ const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
* MD function declarations.
*/
int do_copy_relocations(Obj_Entry *);
-int reloc_non_plt(Obj_Entry *, Obj_Entry *);
+int reloc_non_plt(Obj_Entry *, Obj_Entry *, bool);
int reloc_plt(Obj_Entry *);
int reloc_jmpslots(Obj_Entry *);
void allocate_initial_tls(Obj_Entry *);
diff --git a/sys/amd64/include/elf.h b/sys/amd64/include/elf.h
index e5c95f7..d541b9e 100644
--- a/sys/amd64/include/elf.h
+++ b/sys/amd64/include/elf.h
@@ -87,8 +87,12 @@ __ElfType(Auxinfo);
#define AT_GID 13 /* Real gid. */
#define AT_EGID 14 /* Effective gid. */
#define AT_EXECPATH 15 /* Path to the executable. */
+#define AT_CANARY 16 /* Canary for SSP */
+#define AT_CANARYLEN 17 /* Length of the canary. */
+#define AT_OSRELDATE 18 /* OSRELDATE. */
+#define AT_NCPUS 19 /* Number of CPUs. */
-#define AT_COUNT 16 /* Count of defined aux entry types. */
+#define AT_COUNT 20 /* Count of defined aux entry types. */
/*
* Relocation types.
diff --git a/sys/compat/ia32/ia32_sysvec.c b/sys/compat/ia32/ia32_sysvec.c
index af8168e..acf2c34 100644
--- a/sys/compat/ia32/ia32_sysvec.c
+++ b/sys/compat/ia32/ia32_sysvec.c
@@ -191,6 +191,7 @@ ia32_copyout_strings(struct image_params *imgp)
struct freebsd32_ps_strings *arginfo;
size_t execpath_len;
int szsigcode;
+ char canary[sizeof(long) * 8];
/*
* Calculate string base and vector table pointers.
@@ -203,8 +204,9 @@ ia32_copyout_strings(struct image_params *imgp)
arginfo = (struct freebsd32_ps_strings *)FREEBSD32_PS_STRINGS;
szsigcode = *(imgp->proc->p_sysent->sv_szsigcode);
destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE -
- roundup(execpath_len, sizeof(char *)) -
- roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *));
+ roundup(execpath_len, sizeof(char *)) -
+ roundup(sizeof(canary), sizeof(char *)) -
+ roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *));
/*
* install sigcode
@@ -223,6 +225,14 @@ ia32_copyout_strings(struct image_params *imgp)
}
/*
+ * Prepare the canary for SSP.
+ */
+ arc4rand(canary, sizeof(canary), 0);
+ imgp->canary = (uintptr_t)arginfo - szsigcode - execpath_len -
+ sizeof(canary);
+ copyout(canary, (void *)imgp->canary, sizeof(canary));
+
+ /*
* If we have a valid auxargs ptr, prepare some room
* on the stack.
*/
@@ -239,8 +249,8 @@ ia32_copyout_strings(struct image_params *imgp)
* for argument of Runtime loader.
*/
vectp = (u_int32_t *) (destp - (imgp->args->argc +
- imgp->args->envc + 2 + imgp->auxarg_size + execpath_len) *
- sizeof(u_int32_t));
+ imgp->args->envc + 2 + imgp->auxarg_size)
+ * sizeof(u_int32_t));
} else
/*
* The '+ 2' is for the null pointers at the end of each of
diff --git a/sys/i386/include/elf.h b/sys/i386/include/elf.h
index af71ab8..a959e68 100644
--- a/sys/i386/include/elf.h
+++ b/sys/i386/include/elf.h
@@ -90,8 +90,12 @@ __ElfType(Auxinfo);
#define AT_GID 13 /* Real gid. */
#define AT_EGID 14 /* Effective gid. */
#define AT_EXECPATH 15 /* Path to the executable. */
+#define AT_CANARY 16 /* Canary for SSP. */
+#define AT_CANARYLEN 17 /* Length of the canary. */
+#define AT_OSRELDATE 18 /* OSRELDATE. */
+#define AT_NCPUS 19 /* Number of CPUs. */
-#define AT_COUNT 16 /* Count of defined aux entry types. */
+#define AT_COUNT 20 /* Count of defined aux entry types. */
/*
* Relocation types.
diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index e2c0a12..b2c1d45 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -50,6 +50,7 @@ __FBSDID("$FreeBSD$");
#include <sys/procfs.h>
#include <sys/resourcevar.h>
#include <sys/sf_buf.h>
+#include <sys/smp.h>
#include <sys/systm.h>
#include <sys/signalvar.h>
#include <sys/stat.h>
@@ -887,6 +888,12 @@ __elfN(freebsd_fixup)(register_t **stack_base, struct image_params *imgp)
AUXARGS_ENTRY(pos, AT_BASE, args->base);
if (imgp->execpathp != 0)
AUXARGS_ENTRY(pos, AT_EXECPATH, imgp->execpathp);
+ AUXARGS_ENTRY(pos, AT_OSRELDATE, imgp->proc->p_osrel);
+ if (imgp->canary != 0) {
+ AUXARGS_ENTRY(pos, AT_CANARY, imgp->canary);
+ AUXARGS_ENTRY(pos, AT_CANARYLEN, imgp->canarylen);
+ }
+ AUXARGS_ENTRY(pos, AT_NCPUS, mp_ncpus);
AUXARGS_ENTRY(pos, AT_NULL, 0);
free(imgp->auxargs, M_TEMP);
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index 3f36658..6bed93f 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -380,6 +380,8 @@ do_execve(td, args, mac_p)
imgp->args = args;
imgp->execpath = imgp->freepath = NULL;
imgp->execpathp = 0;
+ imgp->canary = 0;
+ imgp->canarylen = 0;
#ifdef MAC
error = mac_execve_enter(imgp, mac_p);
@@ -1175,6 +1177,7 @@ exec_copyout_strings(imgp)
struct proc *p;
size_t execpath_len;
int szsigcode;
+ char canary[sizeof(long) * 8];
/*
* Calculate string base and vector table pointers.
@@ -1191,6 +1194,7 @@ exec_copyout_strings(imgp)
szsigcode = *(p->p_sysent->sv_szsigcode);
destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE -
roundup(execpath_len, sizeof(char *)) -
+ roundup(sizeof(canary), sizeof(char *)) -
roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *));
/*
@@ -1210,6 +1214,15 @@ exec_copyout_strings(imgp)
}
/*
+ * Prepare the canary for SSP.
+ */
+ arc4rand(canary, sizeof(canary), 0);
+ imgp->canary = (uintptr_t)arginfo - szsigcode - execpath_len -
+ sizeof(canary);
+ copyout(canary, (void *)imgp->canary, sizeof(canary));
+ imgp->canarylen = sizeof(canary);
+
+ /*
* If we have a valid auxargs ptr, prepare some room
* on the stack.
*/
@@ -1226,8 +1239,8 @@ exec_copyout_strings(imgp)
* for argument of Runtime loader.
*/
vectp = (char **)(destp - (imgp->args->argc +
- imgp->args->envc + 2 + imgp->auxarg_size + execpath_len) *
- sizeof(char *));
+ imgp->args->envc + 2 + imgp->auxarg_size)
+ * sizeof(char *));
} else {
/*
* The '+ 2' is for the null pointers at the end of each of
diff --git a/sys/sys/imgact.h b/sys/sys/imgact.h
index e6acc00..8acd184 100644
--- a/sys/sys/imgact.h
+++ b/sys/sys/imgact.h
@@ -69,6 +69,8 @@ struct image_params {
char *execpath;
unsigned long execpathp;
char *freepath;
+ unsigned long canary;
+ int canarylen;
};
#ifdef _KERNEL
diff --git a/sys/sys/link_elf.h b/sys/sys/link_elf.h
index 98840a5..30f3d75 100644
--- a/sys/sys/link_elf.h
+++ b/sys/sys/link_elf.h
@@ -92,6 +92,10 @@ __BEGIN_DECLS
typedef int (*__dl_iterate_hdr_callback)(struct dl_phdr_info *, size_t, void *);
extern int dl_iterate_phdr(__dl_iterate_hdr_callback, void *);
+extern int _rtld_aux_info(int, void *, int);
+#ifndef IN_RTLD
+#pragma weak _rtld_aux_info
+#endif
__END_DECLS
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