mirror/freebsd
1
0
Fork 0
mirror of https://git.FreeBSD.org/src.git synced 2024-12-19 10:53:58 +00:00
Code Issues Releases Activity
888d4d4f86
freebsd/sys/kern/kern_exec.c
Konstantin Belousov 888d4d4f86 When vforked child is traced, the debugging events are not generated 
until child performs exec().  The behaviour is reasonable when a
debugger is the real parent, because the parent is stopped until
exec(), and sending a debugging event to the debugger would deadlock
both parent and child.

On the other hand, when debugger is not the parent of the vforked
child, not sending debugging signals makes it impossible to debug
across vfork.

Fix the issue by declining generating debug signals only when vfork()
was done and child called ptrace(PT_TRACEME).  Set a new process flag
P_PPTRACE from the attach code for PT_TRACEME, if P_PPWAIT flag is
set, which indicates that the process was created with vfork() and
still did not execed. Check P_PPTRACE from issignal(), instead of
refusing the trace outright for the P_PPWAIT case.  The scope of
P_PPTRACE is exactly contained in the scope of P_PPWAIT.

Found and tested by:  zont
Reviewed by:	pluknet
MFC after:	2 weeks
2013-02-07 15:34:22 +00:00

1500 lines
36 KiB
C
Raw Blame History

/*-
* 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("$FreeBSD$");
#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 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)";
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
| 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;
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;
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 = VOP_IS_TEXT(imgp->vp);
VOP_SET_TEXT(imgp->vp);
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)
VOP_UNSET_TEXT(imgp->vp);
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.
*/
VOP_UNSET_TEXT(imgp->vp);
/* 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;
/* set new name to that of the interpreter */
NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
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 | P_PPTRACE);
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 (p->p_tracecred != NULL &&
priv_check_cred(p->p_tracecred, 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)
vrele(textvp);
if (binvp && error != 0)
vrele(binvp);
#ifdef KTRACE
if (tracevp != NULL)
vrele(tracevp);
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
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, writecount;
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.
*/
error = VOP_GET_WRITECOUNT(vp, &writecount);
if (error != 0)
return (error);
if (writecount != 0)
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);
}
Reference in New Issue View Git Blame Copy Permalink