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/*-
* Copyright (c) 1993, David Greenman
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 THE AUTHOR OR CONTRIBUTORS 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>
__FBSDID("$FreeBSD: release/9.1.0/sys/kern/kern_exec.c 238560 2012-07-18 04:52:37Z mjg $");
#include "opt_capsicum.h"
#include "opt_hwpmc_hooks.h"
#include "opt_kdtrace.h"
#include "opt_ktrace.h"
#include "opt_vm.h"
#include <sys/param.h>
#include <sys/capability.h>
#include <sys/systm.h>
#include <sys/capability.h>
#include <sys/eventhandler.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sysproto.h>
#include <sys/signalvar.h>
#include <sys/kernel.h>
#include <sys/mount.h>
#include <sys/filedesc.h>
#include <sys/fcntl.h>
#include <sys/acct.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/imgact_elf.h>
#include <sys/wait.h>
#include <sys/malloc.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/pioctl.h>
#include <sys/namei.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/sdt.h>
#include <sys/sf_buf.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/shm.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <sys/stat.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/vm_object.h>
#include <vm/vm_pager.h>
#ifdef HWPMC_HOOKS
#include <sys/pmckern.h>
#endif
#include <machine/reg.h>
#include <security/audit/audit.h>
#include <security/mac/mac_framework.h>
#ifdef KDTRACE_HOOKS
#include <sys/dtrace_bsd.h>
dtrace_execexit_func_t dtrace_fasttrap_exec;
#endif
SDT_PROVIDER_DECLARE(proc);
SDT_PROBE_DEFINE(proc, kernel, , exec, exec);
SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *");
SDT_PROBE_DEFINE(proc, kernel, , exec_failure, exec-failure);
SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int");
SDT_PROBE_DEFINE(proc, kernel, , exec_success, exec-success);
SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "char *");
MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS);
static int do_execve(struct thread *td, struct image_args *args,
struct mac *mac_p);
/* XXX This should be vm_size_t. */
SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD,
NULL, 0, sysctl_kern_ps_strings, "LU", "");
/* XXX This should be vm_size_t. */
SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD|
CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", "");
SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD,
NULL, 0, sysctl_kern_stackprot, "I", "");
u_long ps_arg_cache_limit = PAGE_SIZE / 16;
SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
&ps_arg_cache_limit, 0, "");
static int map_at_zero = 0;
TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero);
SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0,
"Permit processes to map an object at virtual address 0.");
static int
sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
{
struct proc *p;
int error;
p = curproc;
#ifdef SCTL_MASK32
if (req->flags & SCTL_MASK32) {
unsigned int val;
val = (unsigned int)p->p_sysent->sv_psstrings;
error = SYSCTL_OUT(req, &val, sizeof(val));
} else
#endif
error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings,
sizeof(p->p_sysent->sv_psstrings));
return error;
}
static int
sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
{
struct proc *p;
int error;
p = curproc;
#ifdef SCTL_MASK32
if (req->flags & SCTL_MASK32) {
unsigned int val;
val = (unsigned int)p->p_sysent->sv_usrstack;
error = SYSCTL_OUT(req, &val, sizeof(val));
} else
#endif
error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack,
sizeof(p->p_sysent->sv_usrstack));
return error;
}
static int
sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)
{
struct proc *p;
p = curproc;
return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot,
sizeof(p->p_sysent->sv_stackprot)));
}
/*
* Each of the items is a pointer to a `const struct execsw', hence the
* double pointer here.
*/
static const struct execsw **execsw;
#ifndef _SYS_SYSPROTO_H_
struct execve_args {
char *fname;
char **argv;
char **envv;
};
#endif
int
sys_execve(td, uap)
struct thread *td;
struct execve_args /* {
char *fname;
char **argv;
char **envv;
} */ *uap;
{
int error;
struct image_args args;
error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
uap->argv, uap->envv);
if (error == 0)
error = kern_execve(td, &args, NULL);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct fexecve_args {
int fd;
char **argv;
char **envv;
}
#endif
int
sys_fexecve(struct thread *td, struct fexecve_args *uap)
{
int error;
struct image_args args;
error = exec_copyin_args(&args, NULL, UIO_SYSSPACE,
uap->argv, uap->envv);
if (error == 0) {
args.fd = uap->fd;
error = kern_execve(td, &args, NULL);
}
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct __mac_execve_args {
char *fname;
char **argv;
char **envv;
struct mac *mac_p;
};
#endif
int
sys___mac_execve(td, uap)
struct thread *td;
struct __mac_execve_args /* {
char *fname;
char **argv;
char **envv;
struct mac *mac_p;
} */ *uap;
{
#ifdef MAC
int error;
struct image_args args;
error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
uap->argv, uap->envv);
if (error == 0)
error = kern_execve(td, &args, uap->mac_p);
return (error);
#else
return (ENOSYS);
#endif
}
/*
* XXX: kern_execve has the astonishing property of not always returning to
* the caller. If sufficiently bad things happen during the call to
* do_execve(), it can end up calling exit1(); as a result, callers must
* avoid doing anything which they might need to undo (e.g., allocating
* memory).
*/
int
kern_execve(td, args, mac_p)
struct thread *td;
struct image_args *args;
struct mac *mac_p;
{
struct proc *p = td->td_proc;
int error;
AUDIT_ARG_ARGV(args->begin_argv, args->argc,
args->begin_envv - args->begin_argv);
AUDIT_ARG_ENVV(args->begin_envv, args->envc,
args->endp - args->begin_envv);
if (p->p_flag & P_HADTHREADS) {
PROC_LOCK(p);
if (thread_single(SINGLE_BOUNDARY)) {
PROC_UNLOCK(p);
exec_free_args(args);
return (ERESTART); /* Try again later. */
}
PROC_UNLOCK(p);
}
error = do_execve(td, args, mac_p);
if (p->p_flag & P_HADTHREADS) {
PROC_LOCK(p);
/*
* If success, we upgrade to SINGLE_EXIT state to
* force other threads to suicide.
*/
if (error == 0)
thread_single(SINGLE_EXIT);
else
thread_single_end();
PROC_UNLOCK(p);
}
return (error);
}
/*
* In-kernel implementation of execve(). All arguments are assumed to be
* userspace pointers from the passed thread.
*/
static int
do_execve(td, args, mac_p)
struct thread *td;
struct image_args *args;
struct mac *mac_p;
{
struct proc *p = td->td_proc;
struct nameidata nd;
struct ucred *newcred = NULL, *oldcred;
struct uidinfo *euip;
register_t *stack_base;
int error, i;
struct image_params image_params, *imgp;
struct vattr attr;
int (*img_first)(struct image_params *);
struct pargs *oldargs = NULL, *newargs = NULL;
struct sigacts *oldsigacts, *newsigacts;
#ifdef KTRACE
struct vnode *tracevp = NULL;
struct ucred *tracecred = NULL;
#endif
struct vnode *textvp = NULL, *binvp = NULL;
int credential_changing;
int vfslocked;
int textset;
#ifdef MAC
struct label *interpvplabel = NULL;
int will_transition;
#endif
#ifdef HWPMC_HOOKS
struct pmckern_procexec pe;
#endif
static const char fexecv_proc_title[] = "(fexecv)";
vfslocked = 0;
imgp = &image_params;
/*
* Lock the process and set the P_INEXEC flag to indicate that
* it 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.
*/
PROC_LOCK(p);
KASSERT((p->p_flag & P_INEXEC) == 0,
("%s(): process already has P_INEXEC flag", __func__));
p->p_flag |= P_INEXEC;
PROC_UNLOCK(p);
/*
* Initialize part of the common data
*/
imgp->proc = p;
imgp->execlabel = NULL;
imgp->attr = &attr;
imgp->entry_addr = 0;
imgp->reloc_base = 0;
imgp->vmspace_destroyed = 0;
imgp->interpreted = 0;
imgp->opened = 0;
imgp->interpreter_name = NULL;
imgp->auxargs = NULL;
imgp->vp = NULL;
imgp->object = NULL;
imgp->firstpage = NULL;
imgp->ps_strings = 0;
imgp->auxarg_size = 0;
imgp->args = args;
imgp->execpath = imgp->freepath = NULL;
imgp->execpathp = 0;
imgp->canary = 0;
imgp->canarylen = 0;
imgp->pagesizes = 0;
imgp->pagesizeslen = 0;
imgp->stack_prot = 0;
#ifdef MAC
error = mac_execve_enter(imgp, mac_p);
if (error)
goto exec_fail;
#endif
imgp->image_header = NULL;
/*
* Translate the file name. namei() returns a vnode pointer
* in ni_vp amoung other things.
*
* XXXAUDIT: It would be desirable to also audit the name of the
* interpreter if this is an interpreted binary.
*/
if (args->fname != NULL) {
NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME
| MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td);
}
SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 );
interpret:
if (args->fname != NULL) {
#ifdef CAPABILITY_MODE
/*
* While capability mode can't reach this point via direct
* path arguments to execve(), we also don't allow
* interpreters to be used in capability mode (for now).
* Catch indirect lookups and return a permissions error.
*/
if (IN_CAPABILITY_MODE(td)) {
error = ECAPMODE;
goto exec_fail;
}
#endif
error = namei(&nd);
if (error)
goto exec_fail;
vfslocked = NDHASGIANT(&nd);
binvp = nd.ni_vp;
imgp->vp = binvp;
} else {
AUDIT_ARG_FD(args->fd);
/*
* Some might argue that CAP_READ and/or CAP_MMAP should also
* be required here; such arguments will be entertained.
*
* Descriptors opened only with O_EXEC or O_RDONLY are allowed.
*/
error = fgetvp_exec(td, args->fd, CAP_FEXECVE, &binvp);
if (error)
goto exec_fail;
vfslocked = VFS_LOCK_GIANT(binvp->v_mount);
vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY);
AUDIT_ARG_VNODE1(binvp);
imgp->vp = binvp;
}
/*
* Check file permissions (also 'opens' file)
*/
error = exec_check_permissions(imgp);
if (error)
goto exec_fail_dealloc;
imgp->object = imgp->vp->v_object;
if (imgp->object != NULL)
vm_object_reference(imgp->object);
/*
* Set VV_TEXT now so no one can write to the executable while we're
* activating it.
*
* Remember if this was set before and unset it in case this is not
* actually an executable image.
*/
textset = imgp->vp->v_vflag & VV_TEXT;
ASSERT_VOP_ELOCKED(imgp->vp, "vv_text");
imgp->vp->v_vflag |= VV_TEXT;
error = exec_map_first_page(imgp);
if (error)
goto exec_fail_dealloc;
imgp->proc->p_osrel = 0;
/*
* If the current process has a special image activator it
* wants to try first, call it. For example, emulating shell
* scripts differently.
*/
error = -1;
if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
error = img_first(imgp);
/*
* Loop through the list of image activators, calling each one.
* An activator returns -1 if there is no match, 0 on success,
* and an error otherwise.
*/
for (i = 0; error == -1 && execsw[i]; ++i) {
if (execsw[i]->ex_imgact == NULL ||
execsw[i]->ex_imgact == img_first) {
continue;
}
error = (*execsw[i]->ex_imgact)(imgp);
}
if (error) {
if (error == -1) {
if (textset == 0) {
ASSERT_VOP_ELOCKED(imgp->vp, "vv_text");
imgp->vp->v_vflag &= ~VV_TEXT;
}
error = ENOEXEC;
}
goto exec_fail_dealloc;
}
/*
* Special interpreter operation, cleanup and loop up to try to
* activate the interpreter.
*/
if (imgp->interpreted) {
exec_unmap_first_page(imgp);
/*
* VV_TEXT needs to be unset for scripts. There is a short
* period before we determine that something is a script where
* VV_TEXT will be set. The vnode lock is held over this
* entire period so nothing should illegitimately be blocked.
*/
imgp->vp->v_vflag &= ~VV_TEXT;
/* free name buffer and old vnode */
if (args->fname != NULL)
NDFREE(&nd, NDF_ONLY_PNBUF);
#ifdef MAC
mac_execve_interpreter_enter(binvp, &interpvplabel);
#endif
if (imgp->opened) {
VOP_CLOSE(binvp, FREAD, td->td_ucred, td);
imgp->opened = 0;
}
vput(binvp);
vm_object_deallocate(imgp->object);
imgp->object = NULL;
VFS_UNLOCK_GIANT(vfslocked);
vfslocked = 0;
/* set new name to that of the interpreter */
NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE,
UIO_SYSSPACE, imgp->interpreter_name, td);
args->fname = imgp->interpreter_name;
goto interpret;
}
/*
* NB: We unlock the vnode here because it is believed that none
* of the sv_copyout_strings/sv_fixup operations require the vnode.
*/
VOP_UNLOCK(imgp->vp, 0);
/*
* Do the best to calculate the full path to the image file.
*/
if (imgp->auxargs != NULL &&
((args->fname != NULL && args->fname[0] == '/') ||
vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0))
imgp->execpath = args->fname;
/*
* Copy out strings (args and env) and initialize stack base
*/
if (p->p_sysent->sv_copyout_strings)
stack_base = (*p->p_sysent->sv_copyout_strings)(imgp);
else
stack_base = exec_copyout_strings(imgp);
/*
* If custom stack fixup routine present for this process
* let it do the stack setup.
* Else stuff argument count as first item on stack
*/
if (p->p_sysent->sv_fixup != NULL)
(*p->p_sysent->sv_fixup)(&stack_base, imgp);
else
suword(--stack_base, imgp->args->argc);
/*
* For security and other reasons, the file descriptor table cannot
* be shared after an exec.
*/
fdunshare(p, td);
/*
* Malloc things before we need locks.
*/
newcred = crget();
euip = uifind(attr.va_uid);
i = imgp->args->begin_envv - imgp->args->begin_argv;
/* Cache arguments if they fit inside our allowance */
if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
newargs = pargs_alloc(i);
bcopy(imgp->args->begin_argv, newargs->ar_args, i);
}
/* close files on exec */
fdcloseexec(td);
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
/* Get a reference to the vnode prior to locking the proc */
VREF(binvp);
/*
* For security and other reasons, signal handlers cannot
* be shared after an exec. The new process gets a copy of the old
* handlers. In execsigs(), the new process will have its signals
* reset.
*/
PROC_LOCK(p);
oldcred = crcopysafe(p, newcred);
if (sigacts_shared(p->p_sigacts)) {
oldsigacts = p->p_sigacts;
PROC_UNLOCK(p);
newsigacts = sigacts_alloc();
sigacts_copy(newsigacts, oldsigacts);
PROC_LOCK(p);
p->p_sigacts = newsigacts;
} else
oldsigacts = NULL;
/* Stop profiling */
stopprofclock(p);
/* reset caught signals */
execsigs(p);
/* name this process - nameiexec(p, ndp) */
bzero(p->p_comm, sizeof(p->p_comm));
if (args->fname)
bcopy(nd.ni_cnd.cn_nameptr, p->p_comm,
min(nd.ni_cnd.cn_namelen, MAXCOMLEN));
else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0)
bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title));
bcopy(p->p_comm, td->td_name, sizeof(td->td_name));
#ifdef KTR
sched_clear_tdname(td);
#endif
/*
* mark as execed, wakeup the process that vforked (if any) and tell
* it that it now has its own resources back
*/
p->p_flag |= P_EXEC;
if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
p->p_flag &= ~P_PPWAIT;
cv_broadcast(&p->p_pwait);
}
/*
* Implement image setuid/setgid.
*
* Don't honor setuid/setgid if the filesystem prohibits it or if
* the process is being traced.
*
* We disable setuid/setgid/etc in compatibility mode on the basis
* that most setugid applications are not written with that
* environment in mind, and will therefore almost certainly operate
* incorrectly. In principle there's no reason that setugid
* applications might not be useful in capability mode, so we may want
* to reconsider this conservative design choice in the future.
*
* XXXMAC: For the time being, use NOSUID to also prohibit
* transitions on the file system.
*/
credential_changing = 0;
credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid !=
attr.va_uid;
credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid !=
attr.va_gid;
#ifdef MAC
will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp,
interpvplabel, imgp);
credential_changing |= will_transition;
#endif
if (credential_changing &&
#ifdef CAPABILITY_MODE
((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) &&
#endif
(imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
(p->p_flag & P_TRACED) == 0) {
/*
* Turn off syscall tracing for set-id programs, except for
* root. Record any set-id flags first to make sure that
* we do not regain any tracing during a possible block.
*/
setsugid(p);
#ifdef KTRACE
if (priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0))
ktrprocexec(p, &tracecred, &tracevp);
#endif
/*
* Close any file descriptors 0..2 that reference procfs,
* then make sure file descriptors 0..2 are in use.
*
* setugidsafety() may call closef() and then pfind()
* which may grab the process lock.
* fdcheckstd() may call falloc() which may block to
* allocate memory, so temporarily drop the process lock.
*/
PROC_UNLOCK(p);
VOP_UNLOCK(imgp->vp, 0);
setugidsafety(td);
error = fdcheckstd(td);
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
if (error != 0)
goto done1;
PROC_LOCK(p);
/*
* Set the new credentials.
*/
if (attr.va_mode & S_ISUID)
change_euid(newcred, euip);
if (attr.va_mode & S_ISGID)
change_egid(newcred, attr.va_gid);
#ifdef MAC
if (will_transition) {
mac_vnode_execve_transition(oldcred, newcred, imgp->vp,
interpvplabel, imgp);
}
#endif
/*
* Implement correct POSIX saved-id behavior.
*
* XXXMAC: Note that the current logic will save the
* uid and gid if a MAC domain transition occurs, even
* though maybe it shouldn't.
*/
change_svuid(newcred, newcred->cr_uid);
change_svgid(newcred, newcred->cr_gid);
p->p_ucred = newcred;
newcred = NULL;
} else {
if (oldcred->cr_uid == oldcred->cr_ruid &&
oldcred->cr_gid == oldcred->cr_rgid)
p->p_flag &= ~P_SUGID;
/*
* Implement correct POSIX saved-id behavior.
*
* XXX: It's not clear that the existing behavior is
* POSIX-compliant. A number of sources indicate that the
* saved uid/gid should only be updated if the new ruid is
* not equal to the old ruid, or the new euid is not equal
* to the old euid and the new euid is not equal to the old
* ruid. The FreeBSD code always updates the saved uid/gid.
* Also, this code uses the new (replaced) euid and egid as
* the source, which may or may not be the right ones to use.
*/
if (oldcred->cr_svuid != oldcred->cr_uid ||
oldcred->cr_svgid != oldcred->cr_gid) {
change_svuid(newcred, newcred->cr_uid);
change_svgid(newcred, newcred->cr_gid);
p->p_ucred = newcred;
newcred = NULL;
}
}
/*
* Store the vp for use in procfs. This vnode was referenced prior
* to locking the proc lock.
*/
textvp = p->p_textvp;
p->p_textvp = binvp;
#ifdef KDTRACE_HOOKS
/*
* Tell the DTrace fasttrap provider about the exec if it
* has declared an interest.
*/
if (dtrace_fasttrap_exec)
dtrace_fasttrap_exec(p);
#endif
/*
* Notify others that we exec'd, and clear the P_INEXEC flag
* as we're now a bona fide freshly-execed process.
*/
KNOTE_LOCKED(&p->p_klist, NOTE_EXEC);
p->p_flag &= ~P_INEXEC;
/* clear "fork but no exec" flag, as we _are_ execing */
p->p_acflag &= ~AFORK;
/*
* Free any previous argument cache and replace it with
* the new argument cache, if any.
*/
oldargs = p->p_args;
p->p_args = newargs;
newargs = NULL;
#ifdef HWPMC_HOOKS
/*
* Check if system-wide sampling is in effect or if the
* current process is using PMCs. If so, do exec() time
* processing. This processing needs to happen AFTER the
* P_INEXEC flag is cleared.
*
* The proc lock needs to be released before taking the PMC
* SX.
*/
if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) {
PROC_UNLOCK(p);
VOP_UNLOCK(imgp->vp, 0);
pe.pm_credentialschanged = credential_changing;
pe.pm_entryaddr = imgp->entry_addr;
PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe);
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
} else
PROC_UNLOCK(p);
#else /* !HWPMC_HOOKS */
PROC_UNLOCK(p);
#endif
/* Set values passed into the program in registers. */
if (p->p_sysent->sv_setregs)
(*p->p_sysent->sv_setregs)(td, imgp,
(u_long)(uintptr_t)stack_base);
else
exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base);
vfs_mark_atime(imgp->vp, td->td_ucred);
SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0);
done1:
/*
* Free any resources malloc'd earlier that we didn't use.
*/
uifree(euip);
if (newcred == NULL)
crfree(oldcred);
else
crfree(newcred);
VOP_UNLOCK(imgp->vp, 0);
/*
* Handle deferred decrement of ref counts.
*/
if (textvp != NULL) {
int tvfslocked;
tvfslocked = VFS_LOCK_GIANT(textvp->v_mount);
vrele(textvp);
VFS_UNLOCK_GIANT(tvfslocked);
}
if (binvp && error != 0)
vrele(binvp);
#ifdef KTRACE
if (tracevp != NULL) {
int tvfslocked;
tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount);
vrele(tracevp);
VFS_UNLOCK_GIANT(tvfslocked);
}
if (tracecred != NULL)
crfree(tracecred);
#endif
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
pargs_drop(oldargs);
pargs_drop(newargs);
if (oldsigacts != NULL)
sigacts_free(oldsigacts);
exec_fail_dealloc:
/*
* free various allocated resources
*/
if (imgp->firstpage != NULL)
exec_unmap_first_page(imgp);
if (imgp->vp != NULL) {
if (args->fname)
NDFREE(&nd, NDF_ONLY_PNBUF);
if (imgp->opened)
VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td);
vput(imgp->vp);
}
if (imgp->object != NULL)
vm_object_deallocate(imgp->object);
free(imgp->freepath, M_TEMP);
if (error == 0) {
PROC_LOCK(p);
td->td_dbgflags |= TDB_EXEC;
PROC_UNLOCK(p);
/*
* Stop the process here if its stop event mask has
* the S_EXEC bit set.
*/
STOPEVENT(p, S_EXEC, 0);
goto done2;
}
exec_fail:
/* we're done here, clear P_INEXEC */
PROC_LOCK(p);
p->p_flag &= ~P_INEXEC;
PROC_UNLOCK(p);
SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0);
done2:
#ifdef MAC
mac_execve_exit(imgp);
mac_execve_interpreter_exit(interpvplabel);
#endif
VFS_UNLOCK_GIANT(vfslocked);
exec_free_args(args);
if (error && imgp->vmspace_destroyed) {
/* sorry, no more process anymore. exit gracefully */
exit1(td, W_EXITCODE(0, SIGABRT));
/* NOT REACHED */
}
#ifdef KTRACE
if (error == 0)
ktrprocctor(p);
#endif
return (error);
}
int
exec_map_first_page(imgp)
struct image_params *imgp;
{
int rv, i;
int initial_pagein;
vm_page_t ma[VM_INITIAL_PAGEIN];
vm_object_t object;
if (imgp->firstpage != NULL)
exec_unmap_first_page(imgp);
object = imgp->vp->v_object;
if (object == NULL)
return (EACCES);
VM_OBJECT_LOCK(object);
#if VM_NRESERVLEVEL > 0
if ((object->flags & OBJ_COLORED) == 0) {
object->flags |= OBJ_COLORED;
object->pg_color = 0;
}
#endif
ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
if (ma[0]->valid != VM_PAGE_BITS_ALL) {
initial_pagein = VM_INITIAL_PAGEIN;
if (initial_pagein > object->size)
initial_pagein = object->size;
for (i = 1; i < initial_pagein; i++) {
if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) {
if (ma[i]->valid)
break;
if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy)
break;
vm_page_busy(ma[i]);
} else {
ma[i] = vm_page_alloc(object, i,
VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED);
if (ma[i] == NULL)
break;
}
}
initial_pagein = i;
rv = vm_pager_get_pages(object, ma, initial_pagein, 0);
ma[0] = vm_page_lookup(object, 0);
if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) {
if (ma[0] != NULL) {
vm_page_lock(ma[0]);
vm_page_free(ma[0]);
vm_page_unlock(ma[0]);
}
VM_OBJECT_UNLOCK(object);
return (EIO);
}
}
vm_page_lock(ma[0]);
vm_page_hold(ma[0]);
vm_page_unlock(ma[0]);
vm_page_wakeup(ma[0]);
VM_OBJECT_UNLOCK(object);
imgp->firstpage = sf_buf_alloc(ma[0], 0);
imgp->image_header = (char *)sf_buf_kva(imgp->firstpage);
return (0);
}
void
exec_unmap_first_page(imgp)
struct image_params *imgp;
{
vm_page_t m;
if (imgp->firstpage != NULL) {
m = sf_buf_page(imgp->firstpage);
sf_buf_free(imgp->firstpage);
imgp->firstpage = NULL;
vm_page_lock(m);
vm_page_unhold(m);
vm_page_unlock(m);
}
}
/*
* Destroy old address space, and allocate a new stack
* The new stack is only SGROWSIZ large because it is grown
* automatically in trap.c.
*/
int
exec_new_vmspace(imgp, sv)
struct image_params *imgp;
struct sysentvec *sv;
{
int error;
struct proc *p = imgp->proc;
struct vmspace *vmspace = p->p_vmspace;
vm_object_t obj;
vm_offset_t sv_minuser, stack_addr;
vm_map_t map;
u_long ssiz;
imgp->vmspace_destroyed = 1;
imgp->sysent = sv;
/* May be called with Giant held */
EVENTHANDLER_INVOKE(process_exec, p, imgp);
/*
* Blow away entire process VM, if address space not shared,
* otherwise, create a new VM space so that other threads are
* not disrupted
*/
map = &vmspace->vm_map;
if (map_at_zero)
sv_minuser = sv->sv_minuser;
else
sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE);
if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser &&
vm_map_max(map) == sv->sv_maxuser) {
shmexit(vmspace);
pmap_remove_pages(vmspace_pmap(vmspace));
vm_map_remove(map, vm_map_min(map), vm_map_max(map));
} else {
error = vmspace_exec(p, sv_minuser, sv->sv_maxuser);
if (error)
return (error);
vmspace = p->p_vmspace;
map = &vmspace->vm_map;
}
/* Map a shared page */
obj = sv->sv_shared_page_obj;
if (obj != NULL) {
vm_object_reference(obj);
error = vm_map_fixed(map, obj, 0,
sv->sv_shared_page_base, sv->sv_shared_page_len,
VM_PROT_READ | VM_PROT_EXECUTE, VM_PROT_ALL,
MAP_COPY_ON_WRITE | MAP_ACC_NO_CHARGE);
if (error) {
vm_object_deallocate(obj);
return (error);
}
}
/* Allocate a new stack */
if (sv->sv_maxssiz != NULL)
ssiz = *sv->sv_maxssiz;
else
ssiz = maxssiz;
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 :
sv->sv_stackprot,
VM_PROT_ALL, MAP_STACK_GROWS_DOWN);
if (error)
return (error);
#ifdef __ia64__
/* Allocate a new register stack */
stack_addr = IA64_BACKINGSTORE;
error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz,
sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP);
if (error)
return (error);
#endif
/* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the
* VM_STACK case, but they are still used to monitor the size of the
* process stack so we can check the stack rlimit.
*/
vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz;
return (0);
}
/*
* Copy out argument and environment strings from the old process address
* space into the temporary string buffer.
*/
int
exec_copyin_args(struct image_args *args, char *fname,
enum uio_seg segflg, char **argv, char **envv)
{
char *argp, *envp;
int error;
size_t length;
bzero(args, sizeof(*args));
if (argv == NULL)
return (EFAULT);
/*
* Allocate demand-paged memory for the file name, argument, and
* environment strings.
*/
error = exec_alloc_args(args);
if (error != 0)
return (error);
/*
* Copy the file name.
*/
if (fname != NULL) {
args->fname = args->buf;
error = (segflg == UIO_SYSSPACE) ?
copystr(fname, args->fname, PATH_MAX, &length) :
copyinstr(fname, args->fname, PATH_MAX, &length);
if (error != 0)
goto err_exit;
} else
length = 0;
args->begin_argv = args->buf + length;
args->endp = args->begin_argv;
args->stringspace = ARG_MAX;
/*
* extract arguments first
*/
while ((argp = (caddr_t) (intptr_t) fuword(argv++))) {
if (argp == (caddr_t) -1) {
error = EFAULT;
goto err_exit;
}
if ((error = copyinstr(argp, args->endp,
args->stringspace, &length))) {
if (error == ENAMETOOLONG)
error = E2BIG;
goto err_exit;
}
args->stringspace -= length;
args->endp += length;
args->argc++;
}
args->begin_envv = args->endp;
/*
* extract environment strings
*/
if (envv) {
while ((envp = (caddr_t)(intptr_t)fuword(envv++))) {
if (envp == (caddr_t)-1) {
error = EFAULT;
goto err_exit;
}
if ((error = copyinstr(envp, args->endp,
args->stringspace, &length))) {
if (error == ENAMETOOLONG)
error = E2BIG;
goto err_exit;
}
args->stringspace -= length;
args->endp += length;
args->envc++;
}
}
return (0);
err_exit:
exec_free_args(args);
return (error);
}
/*
* Allocate temporary demand-paged, zero-filled memory for the file name,
* argument, and environment strings. Returns zero if the allocation succeeds
* and ENOMEM otherwise.
*/
int
exec_alloc_args(struct image_args *args)
{
args->buf = (char *)kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX);
return (args->buf != NULL ? 0 : ENOMEM);
}
void
exec_free_args(struct image_args *args)
{
if (args->buf != NULL) {
kmem_free_wakeup(exec_map, (vm_offset_t)args->buf,
PATH_MAX + ARG_MAX);
args->buf = NULL;
}
if (args->fname_buf != NULL) {
free(args->fname_buf, M_TEMP);
args->fname_buf = NULL;
}
}
/*
* 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
* as the initial stack pointer.
*/
register_t *
exec_copyout_strings(imgp)
struct image_params *imgp;
{
int argc, envc;
char **vectp;
char *stringp, *destp;
register_t *stack_base;
struct ps_strings *arginfo;
struct proc *p;
size_t execpath_len;
int szsigcode, szps;
char canary[sizeof(long) * 8];
szps = sizeof(pagesizes[0]) * MAXPAGESIZES;
/*
* Calculate string base and vector table pointers.
* Also deal with signal trampoline code for this exec type.
*/
if (imgp->execpath != NULL && imgp->auxargs != NULL)
execpath_len = strlen(imgp->execpath) + 1;
else
execpath_len = 0;
p = imgp->proc;
szsigcode = 0;
arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
if (p->p_sysent->sv_sigcode_base == 0) {
if (p->p_sysent->sv_szsigcode != NULL)
szsigcode = *(p->p_sysent->sv_szsigcode);
}
destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE -
roundup(execpath_len, sizeof(char *)) -
roundup(sizeof(canary), sizeof(char *)) -
roundup(szps, sizeof(char *)) -
roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *));
/*
* install sigcode
*/
if (szsigcode != 0)
copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo -
szsigcode), szsigcode);
/*
* Copy the image path for the rtld.
*/
if (execpath_len != 0) {
imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len;
copyout(imgp->execpath, (void *)imgp->execpathp,
execpath_len);
}
/*
* 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);
/*
* Prepare the pagesizes array.
*/
imgp->pagesizes = (uintptr_t)arginfo - szsigcode - execpath_len -
roundup(sizeof(canary), sizeof(char *)) - szps;
copyout(pagesizes, (void *)imgp->pagesizes, szps);
imgp->pagesizeslen = szps;
/*
* If we have a valid auxargs ptr, prepare some room
* on the stack.
*/
if (imgp->auxargs) {
/*
* 'AT_COUNT*2' is size for the ELF Auxargs data. This is for
* lower compatibility.
*/
imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size :
(AT_COUNT * 2);
/*
* The '+ 2' is for the null pointers at the end of each of
* the arg and env vector sets,and imgp->auxarg_size is room
* for argument of Runtime loader.
*/
vectp = (char **)(destp - (imgp->args->argc +
imgp->args->envc + 2 + imgp->auxarg_size)
* sizeof(char *));
} else {
/*
* The '+ 2' is for the null pointers at the end of each of
* the arg and env vector sets
*/
vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) *
sizeof(char *));
}
/*
* vectp also becomes our initial stack base
*/
stack_base = (register_t *)vectp;
stringp = imgp->args->begin_argv;
argc = imgp->args->argc;
envc = imgp->args->envc;
/*
* Copy out strings - arguments and environment.
*/
copyout(stringp, destp, ARG_MAX - imgp->args->stringspace);
/*
* Fill in "ps_strings" struct for ps, w, etc.
*/
suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
suword32(&arginfo->ps_nargvstr, argc);
/*
* Fill in argument portion of vector table.
*/
for (; argc > 0; --argc) {
suword(vectp++, (long)(intptr_t)destp);
while (*stringp++ != 0)
destp++;
destp++;
}
/* a null vector table pointer separates the argp's from the envp's */
suword(vectp++, 0);
suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
suword32(&arginfo->ps_nenvstr, envc);
/*
* Fill in environment portion of vector table.
*/
for (; envc > 0; --envc) {
suword(vectp++, (long)(intptr_t)destp);
while (*stringp++ != 0)
destp++;
destp++;
}
/* end of vector table is a null pointer */
suword(vectp, 0);
return (stack_base);
}
/*
* Check permissions of file to execute.
* Called with imgp->vp locked.
* Return 0 for success or error code on failure.
*/
int
exec_check_permissions(imgp)
struct image_params *imgp;
{
struct vnode *vp = imgp->vp;
struct vattr *attr = imgp->attr;
struct thread *td;
int error;
td = curthread;
/* Get file attributes */
error = VOP_GETATTR(vp, attr, td->td_ucred);
if (error)
return (error);
#ifdef MAC
error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp);
if (error)
return (error);
#endif
/*
* 1) Check if file execution is disabled for the filesystem that
* this file resides on.
* 2) Ensure that at least one execute bit is on. Otherwise, a
* privileged user will always succeed, and we don't want this
* to happen unless the file really is executable.
* 3) Ensure that the file is a regular file.
*/
if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
(attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 ||
(attr->va_type != VREG))
return (EACCES);
/*
* Zero length files can't be exec'd
*/
if (attr->va_size == 0)
return (ENOEXEC);
/*
* Check for execute permission to file based on current credentials.
*/
error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
if (error)
return (error);
/*
* Check number of open-for-writes on the file and deny execution
* if there are any.
*/
if (vp->v_writecount)
return (ETXTBSY);
/*
* Call filesystem specific open routine (which does nothing in the
* general case).
*/
error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL);
if (error == 0)
imgp->opened = 1;
return (error);
}
/*
* Exec handler registration
*/
int
exec_register(execsw_arg)
const struct execsw *execsw_arg;
{
const struct execsw **es, **xs, **newexecsw;
int count = 2; /* New slot and trailing NULL */
if (execsw)
for (es = execsw; *es; es++)
count++;
newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
if (newexecsw == NULL)
return (ENOMEM);
xs = newexecsw;
if (execsw)
for (es = execsw; *es; es++)
*xs++ = *es;
*xs++ = execsw_arg;
*xs = NULL;
if (execsw)
free(execsw, M_TEMP);
execsw = newexecsw;
return (0);
}
int
exec_unregister(execsw_arg)
const struct execsw *execsw_arg;
{
const struct execsw **es, **xs, **newexecsw;
int count = 1;
if (execsw == NULL)
panic("unregister with no handlers left?\n");
for (es = execsw; *es; es++) {
if (*es == execsw_arg)
break;
}
if (*es == NULL)
return (ENOENT);
for (es = execsw; *es; es++)
if (*es != execsw_arg)
count++;
newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
if (newexecsw == NULL)
return (ENOMEM);
xs = newexecsw;
for (es = execsw; *es; es++)
if (*es != execsw_arg)
*xs++ = *es;
*xs = NULL;
if (execsw)
free(execsw, M_TEMP);
execsw = newexecsw;
return (0);
}
static vm_object_t shared_page_obj;
static int shared_page_free;
int
shared_page_fill(int size, int align, const char *data)
{
vm_page_t m;
struct sf_buf *s;
vm_offset_t sk;
int res;
VM_OBJECT_LOCK(shared_page_obj);
m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_RETRY);
res = roundup(shared_page_free, align);
if (res + size >= IDX_TO_OFF(shared_page_obj->size))
res = -1;
else {
VM_OBJECT_UNLOCK(shared_page_obj);
s = sf_buf_alloc(m, SFB_DEFAULT);
sk = sf_buf_kva(s);
bcopy(data, (void *)(sk + res), size);
shared_page_free = res + size;
sf_buf_free(s);
VM_OBJECT_LOCK(shared_page_obj);
}
vm_page_wakeup(m);
VM_OBJECT_UNLOCK(shared_page_obj);
return (res);
}
static void
shared_page_init(void *dummy __unused)
{
vm_page_t m;
shared_page_obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE,
VM_PROT_DEFAULT, 0, NULL);
VM_OBJECT_LOCK(shared_page_obj);
m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_RETRY | VM_ALLOC_NOBUSY |
VM_ALLOC_ZERO);
m->valid = VM_PAGE_BITS_ALL;
VM_OBJECT_UNLOCK(shared_page_obj);
}
SYSINIT(shp, SI_SUB_EXEC, SI_ORDER_FIRST, (sysinit_cfunc_t)shared_page_init,
NULL);
void
exec_sysvec_init(void *param)
{
struct sysentvec *sv;
sv = (struct sysentvec *)param;
if ((sv->sv_flags & SV_SHP) == 0)
return;
sv->sv_shared_page_obj = shared_page_obj;
sv->sv_sigcode_base = sv->sv_shared_page_base +
shared_page_fill(*(sv->sv_szsigcode), 16, sv->sv_sigcode);
}