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NetBSD/sys/kern/kern_exec.c
ad 284c2b9aef Merge proc::p_mutex and proc::p_smutex into a single adaptive mutex, since 
we no longer need to guard against access from hardware interrupt handlers.

Additionally, if cloning a process with CLONE_SIGHAND, arrange to have the
child process share the parent's lock so that signal state may be kept in
sync. Partially addresses PR kern/37437.
2008-04-24 18:39:20 +00:00

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/* $NetBSD: kern_exec.c,v 1.272 2008/04/24 18:39:24 ad Exp $ */
/*-
* Copyright (C) 1993, 1994, 1996 Christopher G. Demetriou
* Copyright (C) 1992 Wolfgang Solfrank.
* Copyright (C) 1992 TooLs GmbH.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by TooLs GmbH.
* 4. The name of TooLs GmbH may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.272 2008/04/24 18:39:24 ad Exp $");
#include "opt_ktrace.h"
#include "opt_syscall_debug.h"
#include "opt_compat_netbsd.h"
#include "veriexec.h"
#include "opt_pax.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/kmem.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/acct.h>
#include <sys/exec.h>
#include <sys/ktrace.h>
#include <sys/resourcevar.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/ras.h>
#include <sys/signalvar.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/kauth.h>
#include <sys/lwpctl.h>
#include <sys/pax.h>
#include <sys/cpu.h>
#include <sys/syscallargs.h>
#if NVERIEXEC > 0
#include <sys/verified_exec.h>
#endif /* NVERIEXEC > 0 */
#include <uvm/uvm_extern.h>
#include <machine/reg.h>
#include <compat/common/compat_util.h>
static int exec_sigcode_map(struct proc *, const struct emul *);
#ifdef DEBUG_EXEC
#define DPRINTF(a) uprintf a
#else
#define DPRINTF(a)
#endif /* DEBUG_EXEC */
/*
* Exec function switch:
*
* Note that each makecmds function is responsible for loading the
* exec package with the necessary functions for any exec-type-specific
* handling.
*
* Functions for specific exec types should be defined in their own
* header file.
*/
extern const struct execsw execsw_builtin[];
extern int nexecs_builtin;
static const struct execsw **execsw = NULL;
static int nexecs;
u_int exec_maxhdrsz; /* must not be static - netbsd32 needs it */
#ifdef LKM
/* list of supported emulations */
static
LIST_HEAD(emlist_head, emul_entry) el_head = LIST_HEAD_INITIALIZER(el_head);
struct emul_entry {
LIST_ENTRY(emul_entry) el_list;
const struct emul *el_emul;
int ro_entry;
};
/* list of dynamically loaded execsw entries */
static
LIST_HEAD(execlist_head, exec_entry) ex_head = LIST_HEAD_INITIALIZER(ex_head);
struct exec_entry {
LIST_ENTRY(exec_entry) ex_list;
const struct execsw *es;
};
/* structure used for building execw[] */
struct execsw_entry {
struct execsw_entry *next;
const struct execsw *es;
};
#endif /* LKM */
#ifdef SYSCALL_DEBUG
extern const char * const syscallnames[];
#endif
#ifdef COMPAT_16
extern char sigcode[], esigcode[];
struct uvm_object *emul_netbsd_object;
#endif
#ifndef __HAVE_SYSCALL_INTERN
void syscall(void);
#endif
/* NetBSD emul struct */
const struct emul emul_netbsd = {
"netbsd",
NULL, /* emulation path */
#ifndef __HAVE_MINIMAL_EMUL
EMUL_HAS_SYS___syscall,
NULL,
SYS_syscall,
SYS_NSYSENT,
#endif
sysent,
#ifdef SYSCALL_DEBUG
syscallnames,
#else
NULL,
#endif
sendsig,
trapsignal,
NULL,
#ifdef COMPAT_16
sigcode,
esigcode,
&emul_netbsd_object,
#else
NULL,
NULL,
NULL,
#endif
setregs,
NULL,
NULL,
NULL,
NULL,
NULL,
#ifdef __HAVE_SYSCALL_INTERN
syscall_intern,
#else
syscall,
#endif
NULL,
NULL,
uvm_default_mapaddr,
NULL,
sizeof(ucontext_t),
startlwp,
};
#ifdef LKM
/*
* Exec lock. Used to control access to execsw[] structures.
* This must not be static so that netbsd32 can access it, too.
*/
krwlock_t exec_lock;
static void link_es(struct execsw_entry **, const struct execsw *);
#endif /* LKM */
static kmutex_t sigobject_lock;
/*
* check exec:
* given an "executable" described in the exec package's namei info,
* see what we can do with it.
*
* ON ENTRY:
* exec package with appropriate namei info
* lwp pointer of exec'ing lwp
* NO SELF-LOCKED VNODES
*
* ON EXIT:
* error: nothing held, etc. exec header still allocated.
* ok: filled exec package, executable's vnode (unlocked).
*
* EXEC SWITCH ENTRY:
* Locked vnode to check, exec package, proc.
*
* EXEC SWITCH EXIT:
* ok: return 0, filled exec package, executable's vnode (unlocked).
* error: destructive:
* everything deallocated execept exec header.
* non-destructive:
* error code, executable's vnode (unlocked),
* exec header unmodified.
*/
int
/*ARGSUSED*/
check_exec(struct lwp *l, struct exec_package *epp)
{
int error, i;
struct vnode *vp;
struct nameidata *ndp;
size_t resid;
ndp = epp->ep_ndp;
ndp->ni_cnd.cn_nameiop = LOOKUP;
ndp->ni_cnd.cn_flags = FOLLOW | LOCKLEAF | SAVENAME | TRYEMULROOT;
/* first get the vnode */
if ((error = namei(ndp)) != 0)
return error;
epp->ep_vp = vp = ndp->ni_vp;
/* check access and type */
if (vp->v_type != VREG) {
error = EACCES;
goto bad1;
}
if ((error = VOP_ACCESS(vp, VEXEC, l->l_cred)) != 0)
goto bad1;
/* get attributes */
if ((error = VOP_GETATTR(vp, epp->ep_vap, l->l_cred)) != 0)
goto bad1;
/* Check mount point */
if (vp->v_mount->mnt_flag & MNT_NOEXEC) {
error = EACCES;
goto bad1;
}
if (vp->v_mount->mnt_flag & MNT_NOSUID)
epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID);
/* try to open it */
if ((error = VOP_OPEN(vp, FREAD, l->l_cred)) != 0)
goto bad1;
/* unlock vp, since we need it unlocked from here on out. */
VOP_UNLOCK(vp, 0);
#if NVERIEXEC > 0
error = veriexec_verify(l, vp, ndp->ni_cnd.cn_pnbuf,
epp->ep_flags & EXEC_INDIR ? VERIEXEC_INDIRECT : VERIEXEC_DIRECT,
NULL);
if (error)
goto bad2;
#endif /* NVERIEXEC > 0 */
#ifdef PAX_SEGVGUARD
error = pax_segvguard(l, vp, ndp->ni_cnd.cn_pnbuf, false);
if (error)
goto bad2;
#endif /* PAX_SEGVGUARD */
/* now we have the file, get the exec header */
error = vn_rdwr(UIO_READ, vp, epp->ep_hdr, epp->ep_hdrlen, 0,
UIO_SYSSPACE, 0, l->l_cred, &resid, NULL);
if (error)
goto bad2;
epp->ep_hdrvalid = epp->ep_hdrlen - resid;
/*
* Set up default address space limits. Can be overridden
* by individual exec packages.
*
* XXX probably should be all done in the exec packages.
*/
epp->ep_vm_minaddr = VM_MIN_ADDRESS;
epp->ep_vm_maxaddr = VM_MAXUSER_ADDRESS;
/*
* set up the vmcmds for creation of the process
* address space
*/
error = ENOEXEC;
for (i = 0; i < nexecs; i++) {
int newerror;
epp->ep_esch = execsw[i];
newerror = (*execsw[i]->es_makecmds)(l, epp);
if (!newerror) {
/* Seems ok: check that entry point is sane */
if (epp->ep_entry > VM_MAXUSER_ADDRESS) {
error = ENOEXEC;
break;
}
/* check limits */
if ((epp->ep_tsize > MAXTSIZ) ||
(epp->ep_dsize > (u_quad_t)l->l_proc->p_rlimit
[RLIMIT_DATA].rlim_cur)) {
error = ENOMEM;
break;
}
return 0;
}
if (epp->ep_emul_root != NULL) {
vrele(epp->ep_emul_root);
epp->ep_emul_root = NULL;
}
if (epp->ep_interp != NULL) {
vrele(epp->ep_interp);
epp->ep_interp = NULL;
}
/* make sure the first "interesting" error code is saved. */
if (error == ENOEXEC)
error = newerror;
if (epp->ep_flags & EXEC_DESTR)
/* Error from "#!" code, tidied up by recursive call */
return error;
}
/* not found, error */
/*
* free any vmspace-creation commands,
* and release their references
*/
kill_vmcmds(&epp->ep_vmcmds);
bad2:
/*
* close and release the vnode, restore the old one, free the
* pathname buf, and punt.
*/
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
VOP_CLOSE(vp, FREAD, l->l_cred);
vput(vp);
PNBUF_PUT(ndp->ni_cnd.cn_pnbuf);
return error;
bad1:
/*
* free the namei pathname buffer, and put the vnode
* (which we don't yet have open).
*/
vput(vp); /* was still locked */
PNBUF_PUT(ndp->ni_cnd.cn_pnbuf);
return error;
}
#ifdef __MACHINE_STACK_GROWS_UP
#define STACK_PTHREADSPACE NBPG
#else
#define STACK_PTHREADSPACE 0
#endif
static int
execve_fetch_element(char * const *array, size_t index, char **value)
{
return copyin(array + index, value, sizeof(*value));
}
/*
* exec system call
*/
/* ARGSUSED */
int
sys_execve(struct lwp *l, const struct sys_execve_args *uap, register_t *retval)
{
/* {
syscallarg(const char *) path;
syscallarg(char * const *) argp;
syscallarg(char * const *) envp;
} */
return execve1(l, SCARG(uap, path), SCARG(uap, argp),
SCARG(uap, envp), execve_fetch_element);
}
int
execve1(struct lwp *l, const char *path, char * const *args,
char * const *envs, execve_fetch_element_t fetch_element)
{
int error;
struct exec_package pack;
struct nameidata nid;
struct vattr attr;
struct proc *p;
char *argp;
char *dp, *sp;
long argc, envc;
size_t i, len;
char *stack;
struct ps_strings arginfo;
struct ps_strings *aip = &arginfo;
struct vmspace *vm;
struct exec_fakearg *tmpfap;
int szsigcode;
struct exec_vmcmd *base_vcp;
ksiginfo_t ksi;
ksiginfoq_t kq;
char *pathbuf;
size_t pathbuflen;
p = l->l_proc;
/*
* Check if we have exceeded our number of processes limit.
* This is so that we handle the case where a root daemon
* forked, ran setuid to become the desired user and is trying
* to exec. The obvious place to do the reference counting check
* is setuid(), but we don't do the reference counting check there
* like other OS's do because then all the programs that use setuid()
* must be modified to check the return code of setuid() and exit().
* It is dangerous to make setuid() fail, because it fails open and
* the program will continue to run as root. If we make it succeed
* and return an error code, again we are not enforcing the limit.
* The best place to enforce the limit is here, when the process tries
* to execute a new image, because eventually the process will need
* to call exec in order to do something useful.
*/
if ((p->p_flag & PK_SUGID) &&
chgproccnt(kauth_cred_getuid(l->l_cred), 0) >
p->p_rlimit[RLIMIT_NPROC].rlim_cur)
return EAGAIN;
/*
* Drain existing references and forbid new ones. The process
* should be left alone until we're done here. This is necessary
* to avoid race conditions - e.g. in ptrace() - that might allow
* a local user to illicitly obtain elevated privileges.
*/
rw_enter(&p->p_reflock, RW_WRITER);
base_vcp = NULL;
/*
* Init the namei data to point the file user's program name.
* This is done here rather than in check_exec(), so that it's
* possible to override this settings if any of makecmd/probe
* functions call check_exec() recursively - for example,
* see exec_script_makecmds().
*/
pathbuf = PNBUF_GET();
error = copyinstr(path, pathbuf, MAXPATHLEN, &pathbuflen);
if (error) {
DPRINTF(("execve: copyinstr path %d", error));
goto clrflg;
}
NDINIT(&nid, LOOKUP, NOFOLLOW | TRYEMULROOT, UIO_SYSSPACE, pathbuf);
/*
* initialize the fields of the exec package.
*/
pack.ep_name = path;
pack.ep_hdr = kmem_alloc(exec_maxhdrsz, KM_SLEEP);
pack.ep_hdrlen = exec_maxhdrsz;
pack.ep_hdrvalid = 0;
pack.ep_ndp = &nid;
pack.ep_emul_arg = NULL;
pack.ep_vmcmds.evs_cnt = 0;
pack.ep_vmcmds.evs_used = 0;
pack.ep_vap = &attr;
pack.ep_flags = 0;
pack.ep_emul_root = NULL;
pack.ep_interp = NULL;
pack.ep_esch = NULL;
#ifdef LKM
rw_enter(&exec_lock, RW_READER);
#endif
/* see if we can run it. */
if ((error = check_exec(l, &pack)) != 0) {
if (error != ENOENT) {
DPRINTF(("execve: check exec failed %d\n", error));
}
goto freehdr;
}
/* XXX -- THE FOLLOWING SECTION NEEDS MAJOR CLEANUP */
/* allocate an argument buffer */
argp = (char *) uvm_km_alloc(exec_map, NCARGS, 0,
UVM_KMF_PAGEABLE|UVM_KMF_WAITVA);
#ifdef DIAGNOSTIC
if (argp == NULL)
panic("execve: argp == NULL");
#endif
dp = argp;
argc = 0;
/* copy the fake args list, if there's one, freeing it as we go */
if (pack.ep_flags & EXEC_HASARGL) {
tmpfap = pack.ep_fa;
while (tmpfap->fa_arg != NULL) {
const char *cp;
cp = tmpfap->fa_arg;
while (*cp)
*dp++ = *cp++;
dp++;
kmem_free(tmpfap->fa_arg, tmpfap->fa_len);
tmpfap++; argc++;
}
kmem_free(pack.ep_fa, pack.ep_fa_len);
pack.ep_flags &= ~EXEC_HASARGL;
}
/* Now get argv & environment */
if (args == NULL) {
DPRINTF(("execve: null args\n"));
error = EINVAL;
goto bad;
}
/* 'i' will index the argp/envp element to be retrieved */
i = 0;
if (pack.ep_flags & EXEC_SKIPARG)
i++;
while (1) {
len = argp + ARG_MAX - dp;
if ((error = (*fetch_element)(args, i, &sp)) != 0) {
DPRINTF(("execve: fetch_element args %d\n", error));
goto bad;
}
if (!sp)
break;
if ((error = copyinstr(sp, dp, len, &len)) != 0) {
DPRINTF(("execve: copyinstr args %d\n", error));
if (error == ENAMETOOLONG)
error = E2BIG;
goto bad;
}
ktrexecarg(dp, len - 1);
dp += len;
i++;
argc++;
}
envc = 0;
/* environment need not be there */
if (envs != NULL) {
i = 0;
while (1) {
len = argp + ARG_MAX - dp;
if ((error = (*fetch_element)(envs, i, &sp)) != 0) {
DPRINTF(("execve: fetch_element env %d\n", error));
goto bad;
}
if (!sp)
break;
if ((error = copyinstr(sp, dp, len, &len)) != 0) {
DPRINTF(("execve: copyinstr env %d\n", error));
if (error == ENAMETOOLONG)
error = E2BIG;
goto bad;
}
ktrexecenv(dp, len - 1);
dp += len;
i++;
envc++;
}
}
dp = (char *) ALIGN(dp);
szsigcode = pack.ep_esch->es_emul->e_esigcode -
pack.ep_esch->es_emul->e_sigcode;
#ifdef __MACHINE_STACK_GROWS_UP
/* See big comment lower down */
#define RTLD_GAP 32
#else
#define RTLD_GAP 0
#endif
/* Now check if args & environ fit into new stack */
if (pack.ep_flags & EXEC_32)
len = ((argc + envc + 2 + pack.ep_esch->es_arglen) *
sizeof(int) + sizeof(int) + dp + RTLD_GAP +
szsigcode + sizeof(struct ps_strings) + STACK_PTHREADSPACE)
- argp;
else
len = ((argc + envc + 2 + pack.ep_esch->es_arglen) *
sizeof(char *) + sizeof(int) + dp + RTLD_GAP +
szsigcode + sizeof(struct ps_strings) + STACK_PTHREADSPACE)
- argp;
#ifdef PAX_ASLR
if (pax_aslr_active(l))
len += (arc4random() % PAGE_SIZE);
#endif /* PAX_ASLR */
#ifdef STACKLALIGN /* arm, etc. */
len = STACKALIGN(len); /* make the stack "safely" aligned */
#else
len = ALIGN(len); /* make the stack "safely" aligned */
#endif
if (len > pack.ep_ssize) { /* in effect, compare to initial limit */
DPRINTF(("execve: stack limit exceeded %zu\n", len));
error = ENOMEM;
goto bad;
}
/* Get rid of other LWPs. */
if (p->p_nlwps > 1) {
mutex_enter(p->p_lock);
exit_lwps(l);
mutex_exit(p->p_lock);
}
KDASSERT(p->p_nlwps == 1);
/* Destroy any lwpctl info. */
if (p->p_lwpctl != NULL)
lwp_ctl_exit();
/* This is now LWP 1 */
l->l_lid = 1;
p->p_nlwpid = 1;
/* Remove POSIX timers */
timers_free(p, TIMERS_POSIX);
/* adjust "active stack depth" for process VSZ */
pack.ep_ssize = len; /* maybe should go elsewhere, but... */
/*
* Do whatever is necessary to prepare the address space
* for remapping. Note that this might replace the current
* vmspace with another!
*/
uvmspace_exec(l, pack.ep_vm_minaddr, pack.ep_vm_maxaddr);
/* record proc's vnode, for use by procfs and others */
if (p->p_textvp)
vrele(p->p_textvp);
VREF(pack.ep_vp);
p->p_textvp = pack.ep_vp;
/* Now map address space */
vm = p->p_vmspace;
vm->vm_taddr = (void *)pack.ep_taddr;
vm->vm_tsize = btoc(pack.ep_tsize);
vm->vm_daddr = (void*)pack.ep_daddr;
vm->vm_dsize = btoc(pack.ep_dsize);
vm->vm_ssize = btoc(pack.ep_ssize);
vm->vm_maxsaddr = (void *)pack.ep_maxsaddr;
vm->vm_minsaddr = (void *)pack.ep_minsaddr;
#ifdef PAX_ASLR
pax_aslr_init(l, vm);
#endif /* PAX_ASLR */
/* create the new process's VM space by running the vmcmds */
#ifdef DIAGNOSTIC
if (pack.ep_vmcmds.evs_used == 0)
panic("execve: no vmcmds");
#endif
for (i = 0; i < pack.ep_vmcmds.evs_used && !error; i++) {
struct exec_vmcmd *vcp;
vcp = &pack.ep_vmcmds.evs_cmds[i];
if (vcp->ev_flags & VMCMD_RELATIVE) {
#ifdef DIAGNOSTIC
if (base_vcp == NULL)
panic("execve: relative vmcmd with no base");
if (vcp->ev_flags & VMCMD_BASE)
panic("execve: illegal base & relative vmcmd");
#endif
vcp->ev_addr += base_vcp->ev_addr;
}
error = (*vcp->ev_proc)(l, vcp);
#ifdef DEBUG_EXEC
if (error) {
size_t j;
struct exec_vmcmd *vp = &pack.ep_vmcmds.evs_cmds[0];
for (j = 0; j <= i; j++)
uprintf(
"vmcmd[%zu] = %#lx/%#lx fd@%#lx prot=0%o flags=%d\n",
j, vp[j].ev_addr, vp[j].ev_len,
vp[j].ev_offset, vp[j].ev_prot,
vp[j].ev_flags);
}
#endif /* DEBUG_EXEC */
if (vcp->ev_flags & VMCMD_BASE)
base_vcp = vcp;
}
/* free the vmspace-creation commands, and release their references */
kill_vmcmds(&pack.ep_vmcmds);
vn_lock(pack.ep_vp, LK_EXCLUSIVE | LK_RETRY);
VOP_CLOSE(pack.ep_vp, FREAD, l->l_cred);
vput(pack.ep_vp);
/* if an error happened, deallocate and punt */
if (error) {
DPRINTF(("execve: vmcmd %zu failed: %d\n", i - 1, error));
goto exec_abort;
}
/* remember information about the process */
arginfo.ps_nargvstr = argc;
arginfo.ps_nenvstr = envc;
/* set command name & other accounting info */
i = min(nid.ni_cnd.cn_namelen, MAXCOMLEN);
(void)memcpy(p->p_comm, nid.ni_cnd.cn_nameptr, i);
p->p_comm[i] = '\0';
dp = PNBUF_GET();
/*
* If the path starts with /, we don't need to do any work.
* This handles the majority of the cases.
* In the future perhaps we could canonicalize it?
*/
if (pathbuf[0] == '/')
(void)strlcpy(pack.ep_path = dp, pathbuf, MAXPATHLEN);
#ifdef notyet
/*
* Although this works most of the time [since the entry was just
* entered in the cache] we don't use it because it theoretically
* can fail and it is not the cleanest interface, because there
* could be races. When the namei cache is re-written, this can
* be changed to use the appropriate function.
*/
else if (!(error = vnode_to_path(dp, MAXPATHLEN, p->p_textvp, l, p)))
pack.ep_path = dp;
#endif
else {
#ifdef notyet
printf("Cannot get path for pid %d [%s] (error %d)",
(int)p->p_pid, p->p_comm, error);
#endif
pack.ep_path = NULL;
PNBUF_PUT(dp);
}
stack = (char *)STACK_ALLOC(STACK_GROW(vm->vm_minsaddr,
STACK_PTHREADSPACE + sizeof(struct ps_strings) + szsigcode),
len - (sizeof(struct ps_strings) + szsigcode));
#ifdef __MACHINE_STACK_GROWS_UP
/*
* The copyargs call always copies into lower addresses
* first, moving towards higher addresses, starting with
* the stack pointer that we give. When the stack grows
* down, this puts argc/argv/envp very shallow on the
* stack, right at the first user stack pointer.
* When the stack grows up, the situation is reversed.
*
* Normally, this is no big deal. But the ld_elf.so _rtld()
* function expects to be called with a single pointer to
* a region that has a few words it can stash values into,
* followed by argc/argv/envp. When the stack grows down,
* it's easy to decrement the stack pointer a little bit to
* allocate the space for these few words and pass the new
* stack pointer to _rtld. When the stack grows up, however,
* a few words before argc is part of the signal trampoline, XXX
* so we have a problem.
*
* Instead of changing how _rtld works, we take the easy way
* out and steal 32 bytes before we call copyargs.
* This extra space was allowed for when 'len' was calculated.
*/
stack += RTLD_GAP;
#endif /* __MACHINE_STACK_GROWS_UP */
/* Now copy argc, args & environ to new stack */
error = (*pack.ep_esch->es_copyargs)(l, &pack, &arginfo, &stack, argp);
if (pack.ep_path) {
PNBUF_PUT(pack.ep_path);
pack.ep_path = NULL;
}
if (error) {
DPRINTF(("execve: copyargs failed %d\n", error));
goto exec_abort;
}
/* Move the stack back to original point */
stack = (char *)STACK_GROW(vm->vm_minsaddr, len);
/* fill process ps_strings info */
p->p_psstr = (struct ps_strings *)
STACK_ALLOC(STACK_GROW(vm->vm_minsaddr, STACK_PTHREADSPACE),
sizeof(struct ps_strings));
p->p_psargv = offsetof(struct ps_strings, ps_argvstr);
p->p_psnargv = offsetof(struct ps_strings, ps_nargvstr);
p->p_psenv = offsetof(struct ps_strings, ps_envstr);
p->p_psnenv = offsetof(struct ps_strings, ps_nenvstr);
/* copy out the process's ps_strings structure */
if ((error = copyout(aip, (char *)p->p_psstr,
sizeof(arginfo))) != 0) {
DPRINTF(("execve: ps_strings copyout %p->%p size %ld failed\n",
aip, (char *)p->p_psstr, (long)sizeof(arginfo)));
goto exec_abort;
}
fd_closeexec(); /* handle close on exec */
execsigs(p); /* reset catched signals */
l->l_ctxlink = NULL; /* reset ucontext link */
p->p_acflag &= ~AFORK;
mutex_enter(p->p_lock);
p->p_flag |= PK_EXEC;
mutex_exit(p->p_lock);
/*
* Stop profiling.
*/
if ((p->p_stflag & PST_PROFIL) != 0) {
mutex_spin_enter(&p->p_stmutex);
stopprofclock(p);
mutex_spin_exit(&p->p_stmutex);
}
/*
* It's OK to test PS_PPWAIT unlocked here, as other LWPs have
* exited and exec()/exit() are the only places it will be cleared.
*/
if ((p->p_sflag & PS_PPWAIT) != 0) {
mutex_enter(proc_lock);
mutex_enter(p->p_lock);
p->p_sflag &= ~PS_PPWAIT;
cv_broadcast(&p->p_pptr->p_waitcv);
mutex_exit(p->p_lock);
mutex_exit(proc_lock);
}
/*
* Deal with set[ug]id. MNT_NOSUID has already been used to disable
* s[ug]id. It's OK to check for PSL_TRACED here as we have blocked
* out additional references on the process for the moment.
*/
if ((p->p_slflag & PSL_TRACED) == 0 &&
(((attr.va_mode & S_ISUID) != 0 &&
kauth_cred_geteuid(l->l_cred) != attr.va_uid) ||
((attr.va_mode & S_ISGID) != 0 &&
kauth_cred_getegid(l->l_cred) != attr.va_gid))) {
/*
* Mark the process as SUGID before we do
* anything that might block.
*/
proc_crmod_enter();
proc_crmod_leave(NULL, NULL, true);
/* Make sure file descriptors 0..2 are in use. */
if ((error = fd_checkstd()) != 0) {
DPRINTF(("execve: fdcheckstd failed %d\n", error));
goto exec_abort;
}
/*
* Copy the credential so other references don't see our
* changes.
*/
l->l_cred = kauth_cred_copy(l->l_cred);
#ifdef KTRACE
/*
* If the persistent trace flag isn't set, turn off.
*/
if (p->p_tracep) {
mutex_enter(&ktrace_lock);
if (!(p->p_traceflag & KTRFAC_PERSISTENT))
ktrderef(p);
mutex_exit(&ktrace_lock);
}
#endif
if (attr.va_mode & S_ISUID)
kauth_cred_seteuid(l->l_cred, attr.va_uid);
if (attr.va_mode & S_ISGID)
kauth_cred_setegid(l->l_cred, attr.va_gid);
} else {
if (kauth_cred_geteuid(l->l_cred) ==
kauth_cred_getuid(l->l_cred) &&
kauth_cred_getegid(l->l_cred) ==
kauth_cred_getgid(l->l_cred))
p->p_flag &= ~PK_SUGID;
}
/*
* Copy the credential so other references don't see our changes.
* Test to see if this is necessary first, since in the common case
* we won't need a private reference.
*/
if (kauth_cred_geteuid(l->l_cred) != kauth_cred_getsvuid(l->l_cred) ||
kauth_cred_getegid(l->l_cred) != kauth_cred_getsvgid(l->l_cred)) {
l->l_cred = kauth_cred_copy(l->l_cred);
kauth_cred_setsvuid(l->l_cred, kauth_cred_geteuid(l->l_cred));
kauth_cred_setsvgid(l->l_cred, kauth_cred_getegid(l->l_cred));
}
/* Update the master credentials. */
if (l->l_cred != p->p_cred) {
kauth_cred_t ocred;
kauth_cred_hold(l->l_cred);
mutex_enter(p->p_lock);
ocred = p->p_cred;
p->p_cred = l->l_cred;
mutex_exit(p->p_lock);
kauth_cred_free(ocred);
}
#if defined(__HAVE_RAS)
/*
* Remove all RASs from the address space.
*/
ras_purgeall();
#endif
doexechooks(p);
uvm_km_free(exec_map, (vaddr_t) argp, NCARGS, UVM_KMF_PAGEABLE);
PNBUF_PUT(nid.ni_cnd.cn_pnbuf);
/* notify others that we exec'd */
KNOTE(&p->p_klist, NOTE_EXEC);
/* setup new registers and do misc. setup. */
(*pack.ep_esch->es_emul->e_setregs)(l, &pack, (u_long) stack);
if (pack.ep_esch->es_setregs)
(*pack.ep_esch->es_setregs)(l, &pack, (u_long) stack);
/* map the process's signal trampoline code */
if (exec_sigcode_map(p, pack.ep_esch->es_emul)) {
DPRINTF(("execve: map sigcode failed %d\n", error));
goto exec_abort;
}
kmem_free(pack.ep_hdr, pack.ep_hdrlen);
/* The emulation root will usually have been found when we looked
* for the elf interpreter (or similar), if not look now. */
if (pack.ep_esch->es_emul->e_path != NULL && pack.ep_emul_root == NULL)
emul_find_root(l, &pack);
/* Any old emulation root got removed by fdcloseexec */
rw_enter(&p->p_cwdi->cwdi_lock, RW_WRITER);
p->p_cwdi->cwdi_edir = pack.ep_emul_root;
rw_exit(&p->p_cwdi->cwdi_lock);
pack.ep_emul_root = NULL;
if (pack.ep_interp != NULL)
vrele(pack.ep_interp);
/*
* Call emulation specific exec hook. This can setup per-process
* p->p_emuldata or do any other per-process stuff an emulation needs.
*
* If we are executing process of different emulation than the
* original forked process, call e_proc_exit() of the old emulation
* first, then e_proc_exec() of new emulation. If the emulation is
* same, the exec hook code should deallocate any old emulation
* resources held previously by this process.
*/
if (p->p_emul && p->p_emul->e_proc_exit
&& p->p_emul != pack.ep_esch->es_emul)
(*p->p_emul->e_proc_exit)(p);
/*
* Call exec hook. Emulation code may NOT store reference to anything
* from &pack.
*/
if (pack.ep_esch->es_emul->e_proc_exec)
(*pack.ep_esch->es_emul->e_proc_exec)(p, &pack);
/* update p_emul, the old value is no longer needed */
p->p_emul = pack.ep_esch->es_emul;
/* ...and the same for p_execsw */
p->p_execsw = pack.ep_esch;
#ifdef __HAVE_SYSCALL_INTERN
(*p->p_emul->e_syscall_intern)(p);
#endif
ktremul();
/* Allow new references from the debugger/procfs. */
rw_exit(&p->p_reflock);
#ifdef LKM
rw_exit(&exec_lock);
#endif
mutex_enter(proc_lock);
if ((p->p_slflag & (PSL_TRACED|PSL_SYSCALL)) == PSL_TRACED) {
KSI_INIT_EMPTY(&ksi);
ksi.ksi_signo = SIGTRAP;
ksi.ksi_lid = l->l_lid;
kpsignal(p, &ksi, NULL);
}
if (p->p_sflag & PS_STOPEXEC) {
KERNEL_UNLOCK_ALL(l, &l->l_biglocks);
p->p_pptr->p_nstopchild++;
p->p_pptr->p_waited = 0;
mutex_enter(p->p_lock);
ksiginfo_queue_init(&kq);
sigclearall(p, &contsigmask, &kq);
lwp_lock(l);
l->l_stat = LSSTOP;
p->p_stat = SSTOP;
p->p_nrlwps--;
mutex_exit(p->p_lock);
mutex_exit(proc_lock);
mi_switch(l);
ksiginfo_queue_drain(&kq);
KERNEL_LOCK(l->l_biglocks, l);
} else {
mutex_exit(proc_lock);
}
PNBUF_PUT(pathbuf);
return (EJUSTRETURN);
bad:
/* free the vmspace-creation commands, and release their references */
kill_vmcmds(&pack.ep_vmcmds);
/* kill any opened file descriptor, if necessary */
if (pack.ep_flags & EXEC_HASFD) {
pack.ep_flags &= ~EXEC_HASFD;
fd_close(pack.ep_fd);
}
/* close and put the exec'd file */
vn_lock(pack.ep_vp, LK_EXCLUSIVE | LK_RETRY);
VOP_CLOSE(pack.ep_vp, FREAD, l->l_cred);
vput(pack.ep_vp);
PNBUF_PUT(nid.ni_cnd.cn_pnbuf);
uvm_km_free(exec_map, (vaddr_t) argp, NCARGS, UVM_KMF_PAGEABLE);
freehdr:
kmem_free(pack.ep_hdr, pack.ep_hdrlen);
if (pack.ep_emul_root != NULL)
vrele(pack.ep_emul_root);
if (pack.ep_interp != NULL)
vrele(pack.ep_interp);
clrflg:
PNBUF_PUT(pathbuf);
rw_exit(&p->p_reflock);
#ifdef LKM
rw_exit(&exec_lock);
#endif
return error;
exec_abort:
PNBUF_PUT(pathbuf);
rw_exit(&p->p_reflock);
#ifdef LKM
rw_exit(&exec_lock);
#endif
/*
* the old process doesn't exist anymore. exit gracefully.
* get rid of the (new) address space we have created, if any, get rid
* of our namei data and vnode, and exit noting failure
*/
uvm_deallocate(&vm->vm_map, VM_MIN_ADDRESS,
VM_MAXUSER_ADDRESS - VM_MIN_ADDRESS);
if (pack.ep_emul_arg)
FREE(pack.ep_emul_arg, M_TEMP);
PNBUF_PUT(nid.ni_cnd.cn_pnbuf);
uvm_km_free(exec_map, (vaddr_t) argp, NCARGS, UVM_KMF_PAGEABLE);
kmem_free(pack.ep_hdr, pack.ep_hdrlen);
if (pack.ep_emul_root != NULL)
vrele(pack.ep_emul_root);
if (pack.ep_interp != NULL)
vrele(pack.ep_interp);
/* Acquire the sched-state mutex (exit1() will release it). */
mutex_enter(p->p_lock);
exit1(l, W_EXITCODE(error, SIGABRT));
/* NOTREACHED */
return 0;
}
int
copyargs(struct lwp *l, struct exec_package *pack, struct ps_strings *arginfo,
char **stackp, void *argp)
{
char **cpp, *dp, *sp;
size_t len;
void *nullp;
long argc, envc;
int error;
cpp = (char **)*stackp;
nullp = NULL;
argc = arginfo->ps_nargvstr;
envc = arginfo->ps_nenvstr;
if ((error = copyout(&argc, cpp++, sizeof(argc))) != 0)
return error;
dp = (char *) (cpp + argc + envc + 2 + pack->ep_esch->es_arglen);
sp = argp;
/* XXX don't copy them out, remap them! */
arginfo->ps_argvstr = cpp; /* remember location of argv for later */
for (; --argc >= 0; sp += len, dp += len)
if ((error = copyout(&dp, cpp++, sizeof(dp))) != 0 ||
(error = copyoutstr(sp, dp, ARG_MAX, &len)) != 0)
return error;
if ((error = copyout(&nullp, cpp++, sizeof(nullp))) != 0)
return error;
arginfo->ps_envstr = cpp; /* remember location of envp for later */
for (; --envc >= 0; sp += len, dp += len)
if ((error = copyout(&dp, cpp++, sizeof(dp))) != 0 ||
(error = copyoutstr(sp, dp, ARG_MAX, &len)) != 0)
return error;
if ((error = copyout(&nullp, cpp++, sizeof(nullp))) != 0)
return error;
*stackp = (char *)cpp;
return 0;
}
#ifdef LKM
/*
* Find an emulation of given name in list of emulations.
* Needs to be called with the exec_lock held.
*/
const struct emul *
emul_search(const char *name)
{
struct emul_entry *it;
LIST_FOREACH(it, &el_head, el_list) {
if (strcmp(name, it->el_emul->e_name) == 0)
return it->el_emul;
}
return NULL;
}
/*
* Add an emulation to list, if it's not there already.
*/
int
emul_register(const struct emul *emul, int ro_entry)
{
struct emul_entry *ee;
int error;
error = 0;
rw_enter(&exec_lock, RW_WRITER);
if (emul_search(emul->e_name)) {
error = EEXIST;
goto out;
}
ee = kmem_alloc(sizeof(*ee), KM_SLEEP);
ee->el_emul = emul;
ee->ro_entry = ro_entry;
LIST_INSERT_HEAD(&el_head, ee, el_list);
out:
rw_exit(&exec_lock);
return error;
}
/*
* Remove emulation with name 'name' from list of supported emulations.
*/
int
emul_unregister(const char *name)
{
const struct proclist_desc *pd;
struct emul_entry *it;
int i, error;
struct proc *ptmp;
error = 0;
rw_enter(&exec_lock, RW_WRITER);
LIST_FOREACH(it, &el_head, el_list) {
if (strcmp(it->el_emul->e_name, name) == 0)
break;
}
if (!it) {
error = ENOENT;
goto out;
}
if (it->ro_entry) {
error = EBUSY;
goto out;
}
/* test if any execw[] entry is still using this */
for(i=0; i < nexecs; i++) {
if (execsw[i]->es_emul == it->el_emul) {
error = EBUSY;
goto out;
}
}
/*
* Test if any process is running under this emulation - since
* emul_unregister() is running quite sendomly, it's better
* to do expensive check here than to use any locking.
*/
mutex_enter(proc_lock);
for (pd = proclists; pd->pd_list != NULL && !error; pd++) {
PROCLIST_FOREACH(ptmp, pd->pd_list) {
if (ptmp->p_emul == it->el_emul) {
error = EBUSY;
break;
}
}
}
mutex_exit(proc_lock);
if (error)
goto out;
/* entry is not used, remove it */
LIST_REMOVE(it, el_list);
kmem_free(it, sizeof(*it));
out:
rw_exit(&exec_lock);
return error;
}
/*
* Add execsw[] entry.
*/
int
exec_add(struct execsw *esp, const char *e_name)
{
struct exec_entry *it;
int error;
error = 0;
rw_enter(&exec_lock, RW_WRITER);
if (!esp->es_emul) {
esp->es_emul = emul_search(e_name);
if (!esp->es_emul) {
error = ENOENT;
goto out;
}
}
LIST_FOREACH(it, &ex_head, ex_list) {
/* assume tuple (makecmds, probe_func, emulation) is unique */
if (it->es->es_makecmds == esp->es_makecmds
&& it->es->u.elf_probe_func == esp->u.elf_probe_func
&& it->es->es_emul == esp->es_emul) {
error = EEXIST;
goto out;
}
}
/* if we got here, the entry doesn't exist yet */
it = kmem_alloc(sizeof(*it), KM_SLEEP);
it->es = esp;
LIST_INSERT_HEAD(&ex_head, it, ex_list);
/* update execsw[] */
exec_init(0);
out:
rw_exit(&exec_lock);
return error;
}
/*
* Remove execsw[] entry.
*/
int
exec_remove(const struct execsw *esp)
{
struct exec_entry *it;
int error;
error = 0;
rw_enter(&exec_lock, RW_WRITER);
LIST_FOREACH(it, &ex_head, ex_list) {
/* assume tuple (makecmds, probe_func, emulation) is unique */
if (it->es->es_makecmds == esp->es_makecmds
&& it->es->u.elf_probe_func == esp->u.elf_probe_func
&& it->es->es_emul == esp->es_emul)
break;
}
if (!it) {
error = ENOENT;
goto out;
}
/* remove item from list and free resources */
LIST_REMOVE(it, ex_list);
kmem_free(it, sizeof(*it));
/* update execsw[] */
exec_init(0);
out:
rw_exit(&exec_lock);
return error;
}
static void
link_es(struct execsw_entry **listp, const struct execsw *esp)
{
struct execsw_entry *et, *e1;
et = (struct execsw_entry *) malloc(sizeof(struct execsw_entry),
M_TEMP, M_WAITOK);
et->next = NULL;
et->es = esp;
if (*listp == NULL) {
*listp = et;
return;
}
switch(et->es->es_prio) {
case EXECSW_PRIO_FIRST:
/* put new entry as the first */
et->next = *listp;
*listp = et;
break;
case EXECSW_PRIO_ANY:
/* put new entry after all *_FIRST and *_ANY entries */
for(e1 = *listp; e1->next
&& e1->next->es->es_prio != EXECSW_PRIO_LAST;
e1 = e1->next);
et->next = e1->next;
e1->next = et;
break;
case EXECSW_PRIO_LAST:
/* put new entry as the last one */
for(e1 = *listp; e1->next; e1 = e1->next);
e1->next = et;
break;
default:
#ifdef DIAGNOSTIC
panic("execw[] entry with unknown priority %d found",
et->es->es_prio);
#else
free(et, M_TEMP);
#endif
break;
}
}
/*
* Initialize exec structures. If init_boot is true, also does necessary
* one-time initialization (it's called from main() that way).
* Once system is multiuser, this should be called with exec_lock held,
* i.e. via exec_{add|remove}().
*/
int
exec_init(int init_boot)
{
const struct execsw **new_es, * const *old_es;
struct execsw_entry *list, *e1;
struct exec_entry *e2;
int i, es_sz;
if (init_boot) {
/* do one-time initializations */
rw_init(&exec_lock);
mutex_init(&sigobject_lock, MUTEX_DEFAULT, IPL_NONE);
/* register compiled-in emulations */
for(i=0; i < nexecs_builtin; i++) {
if (execsw_builtin[i].es_emul)
emul_register(execsw_builtin[i].es_emul, 1);
}
#ifdef DIAGNOSTIC
if (i == 0)
panic("no emulations found in execsw_builtin[]");
#endif
}
/*
* Build execsw[] array from builtin entries and entries added
* at runtime.
*/
list = NULL;
for(i=0; i < nexecs_builtin; i++)
link_es(&list, &execsw_builtin[i]);
/* Add dynamically loaded entries */
es_sz = nexecs_builtin;
LIST_FOREACH(e2, &ex_head, ex_list) {
link_es(&list, e2->es);
es_sz++;
}
/*
* Now that we have sorted all execw entries, create new execsw[]
* and free no longer needed memory in the process.
*/
new_es = kmem_alloc(es_sz * sizeof(struct execsw *), KM_SLEEP);
for(i=0; list; i++) {
new_es[i] = list->es;
e1 = list->next;
free(list, M_TEMP);
list = e1;
}
/*
* New execsw[] array built, now replace old execsw[] and free
* used memory.
*/
old_es = execsw;
if (old_es)
/*XXXUNCONST*/
kmem_free(__UNCONST(old_es), nexecs * sizeof(struct execsw *));
execsw = new_es;
nexecs = es_sz;
/*
* Figure out the maximum size of an exec header.
*/
exec_maxhdrsz = 0;
for (i = 0; i < nexecs; i++) {
if (execsw[i]->es_hdrsz > exec_maxhdrsz)
exec_maxhdrsz = execsw[i]->es_hdrsz;
}
return 0;
}
#endif
#ifndef LKM
/*
* Simplified exec_init() for kernels without LKMs. Only initialize
* exec_maxhdrsz and execsw[].
*/
int
exec_init(int init_boot)
{
int i;
#ifdef DIAGNOSTIC
if (!init_boot)
panic("exec_init(): called with init_boot == 0");
#endif
/* do one-time initializations */
nexecs = nexecs_builtin;
execsw = kmem_alloc(nexecs * sizeof(struct execsw *), KM_SLEEP);
/*
* Fill in execsw[] and figure out the maximum size of an exec header.
*/
exec_maxhdrsz = 0;
for(i=0; i < nexecs; i++) {
execsw[i] = &execsw_builtin[i];
if (execsw_builtin[i].es_hdrsz > exec_maxhdrsz)
exec_maxhdrsz = execsw_builtin[i].es_hdrsz;
}
return 0;
}
#endif /* !LKM */
static int
exec_sigcode_map(struct proc *p, const struct emul *e)
{
vaddr_t va;
vsize_t sz;
int error;
struct uvm_object *uobj;
sz = (vaddr_t)e->e_esigcode - (vaddr_t)e->e_sigcode;
if (e->e_sigobject == NULL || sz == 0) {
return 0;
}
/*
* If we don't have a sigobject for this emulation, create one.
*
* sigobject is an anonymous memory object (just like SYSV shared
* memory) that we keep a permanent reference to and that we map
* in all processes that need this sigcode. The creation is simple,
* we create an object, add a permanent reference to it, map it in
* kernel space, copy out the sigcode to it and unmap it.
* We map it with PROT_READ|PROT_EXEC into the process just
* the way sys_mmap() would map it.
*/
uobj = *e->e_sigobject;
if (uobj == NULL) {
mutex_enter(&sigobject_lock);
if ((uobj = *e->e_sigobject) == NULL) {
uobj = uao_create(sz, 0);
(*uobj->pgops->pgo_reference)(uobj);
va = vm_map_min(kernel_map);
if ((error = uvm_map(kernel_map, &va, round_page(sz),
uobj, 0, 0,
UVM_MAPFLAG(UVM_PROT_RW, UVM_PROT_RW,
UVM_INH_SHARE, UVM_ADV_RANDOM, 0)))) {
printf("kernel mapping failed %d\n", error);
(*uobj->pgops->pgo_detach)(uobj);
mutex_exit(&sigobject_lock);
return (error);
}
memcpy((void *)va, e->e_sigcode, sz);
#ifdef PMAP_NEED_PROCWR
pmap_procwr(&proc0, va, sz);
#endif
uvm_unmap(kernel_map, va, va + round_page(sz));
*e->e_sigobject = uobj;
}
mutex_exit(&sigobject_lock);
}
/* Just a hint to uvm_map where to put it. */
va = e->e_vm_default_addr(p, (vaddr_t)p->p_vmspace->vm_daddr,
round_page(sz));
#ifdef __alpha__
/*
* Tru64 puts /sbin/loader at the end of user virtual memory,
* which causes the above calculation to put the sigcode at
* an invalid address. Put it just below the text instead.
*/
if (va == (vaddr_t)vm_map_max(&p->p_vmspace->vm_map)) {
va = (vaddr_t)p->p_vmspace->vm_taddr - round_page(sz);
}
#endif
(*uobj->pgops->pgo_reference)(uobj);
error = uvm_map(&p->p_vmspace->vm_map, &va, round_page(sz),
uobj, 0, 0,
UVM_MAPFLAG(UVM_PROT_RX, UVM_PROT_RX, UVM_INH_SHARE,
UVM_ADV_RANDOM, 0));
if (error) {
(*uobj->pgops->pgo_detach)(uobj);
return (error);
}
p->p_sigctx.ps_sigcode = (void *)va;
return (0);
}
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