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1314d14c32
freebsd/sys/kern/kern_exec.c
Jake Freeland 0cd9cde767 ktrace: Record namei violations with KTR_CAPFAIL 
Report namei path lookups while Capsicum violation tracing with
CAPFAIL_NAMEI. vfs caching is also ignored when tracing to mimic
capability mode behavior.

Reviewed by:	markj
Approved by:	markj (mentor)
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D40680
2024-04-07 18:52:51 -05:00

2095 lines
53 KiB
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/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* 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>
#include "opt_capsicum.h"
#include "opt_hwpmc_hooks.h"
#include "opt_ktrace.h"
#include "opt_vm.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/acct.h>
#include <sys/asan.h>
#include <sys/capsicum.h>
#include <sys/compressor.h>
#include <sys/eventhandler.h>
#include <sys/exec.h>
#include <sys/fcntl.h>
#include <sys/filedesc.h>
#include <sys/imgact.h>
#include <sys/imgact_elf.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/ptrace.h>
#include <sys/reg.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/sched.h>
#include <sys/sdt.h>
#include <sys/sf_buf.h>
#include <sys/shm.h>
#include <sys/signalvar.h>
#include <sys/smp.h>
#include <sys/stat.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>
#include <sys/timers.h>
#include <sys/umtxvar.h>
#include <sys/vnode.h>
#include <sys/wait.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 <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_DEFINE1(proc, , , exec, "char *");
SDT_PROBE_DEFINE1(proc, , , exec__failure, "int");
SDT_PROBE_DEFINE1(proc, , , exec__success, "char *");
MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
int coredump_pack_fileinfo = 1;
SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN,
&coredump_pack_fileinfo, 0,
"Enable file path packing in 'procstat -f' coredump notes");
int coredump_pack_vmmapinfo = 1;
SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN,
&coredump_pack_vmmapinfo, 0,
"Enable file path packing in 'procstat -v' coredump notes");
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, struct vmspace *oldvmspace);
/* XXX This should be vm_size_t. */
SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD|
CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_ps_strings, "LU",
"Location of process' ps_strings structure");
/* XXX This should be vm_size_t. */
SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD|
CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_usrstack, "LU",
"Top of process stack");
SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD|CTLFLAG_MPSAFE,
NULL, 0, sysctl_kern_stackprot, "I",
"Stack memory permissions");
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,
"Process' command line characters cache limit");
static int disallow_high_osrel;
SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW,
&disallow_high_osrel, 0,
"Disallow execution of binaries built for higher version of the world");
static int map_at_zero = 0;
SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0,
"Permit processes to map an object at virtual address 0.");
static int core_dump_can_intr = 1;
SYSCTL_INT(_kern, OID_AUTO, core_dump_can_intr, CTLFLAG_RWTUN,
&core_dump_can_intr, 0,
"Core dumping interruptible with SIGKILL");
static int
sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
{
struct proc *p;
vm_offset_t ps_strings;
p = curproc;
#ifdef SCTL_MASK32
if (req->flags & SCTL_MASK32) {
unsigned int val;
val = (unsigned int)PROC_PS_STRINGS(p);
return (SYSCTL_OUT(req, &val, sizeof(val)));
}
#endif
ps_strings = PROC_PS_STRINGS(p);
return (SYSCTL_OUT(req, &ps_strings, sizeof(ps_strings)));
}
static int
sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
{
struct proc *p;
vm_offset_t val;
p = curproc;
#ifdef SCTL_MASK32
if (req->flags & SCTL_MASK32) {
unsigned int val32;
val32 = round_page((unsigned int)p->p_vmspace->vm_stacktop);
return (SYSCTL_OUT(req, &val32, sizeof(val32)));
}
#endif
val = round_page(p->p_vmspace->vm_stacktop);
return (SYSCTL_OUT(req, &val, sizeof(val)));
}
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(struct thread *td, struct execve_args *uap)
{
struct image_args args;
struct vmspace *oldvmspace;
int error;
error = pre_execve(td, &oldvmspace);
if (error != 0)
return (error);
error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
uap->argv, uap->envv);
if (error == 0)
error = kern_execve(td, &args, NULL, oldvmspace);
post_execve(td, error, oldvmspace);
AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
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)
{
struct image_args args;
struct vmspace *oldvmspace;
int error;
error = pre_execve(td, &oldvmspace);
if (error != 0)
return (error);
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, oldvmspace);
}
post_execve(td, error, oldvmspace);
AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
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(struct thread *td, struct __mac_execve_args *uap)
{
#ifdef MAC
struct image_args args;
struct vmspace *oldvmspace;
int error;
error = pre_execve(td, &oldvmspace);
if (error != 0)
return (error);
error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
uap->argv, uap->envv);
if (error == 0)
error = kern_execve(td, &args, uap->mac_p, oldvmspace);
post_execve(td, error, oldvmspace);
AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
return (error);
#else
return (ENOSYS);
#endif
}
int
pre_execve(struct thread *td, struct vmspace **oldvmspace)
{
struct proc *p;
int error;
KASSERT(td == curthread, ("non-current thread %p", td));
error = 0;
p = td->td_proc;
if ((p->p_flag & P_HADTHREADS) != 0) {
PROC_LOCK(p);
if (thread_single(p, SINGLE_BOUNDARY) != 0)
error = ERESTART;
PROC_UNLOCK(p);
}
KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0,
("nested execve"));
*oldvmspace = p->p_vmspace;
return (error);
}
void
post_execve(struct thread *td, int error, struct vmspace *oldvmspace)
{
struct proc *p;
KASSERT(td == curthread, ("non-current thread %p", td));
p = td->td_proc;
if ((p->p_flag & P_HADTHREADS) != 0) {
PROC_LOCK(p);
/*
* If success, we upgrade to SINGLE_EXIT state to
* force other threads to suicide.
*/
if (error == EJUSTRETURN)
thread_single(p, SINGLE_EXIT);
else
thread_single_end(p, SINGLE_BOUNDARY);
PROC_UNLOCK(p);
}
exec_cleanup(td, oldvmspace);
}
/*
* 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(struct thread *td, struct image_args *args, struct mac *mac_p,
struct vmspace *oldvmspace)
{
TSEXEC(td->td_proc->p_pid, args->begin_argv);
AUDIT_ARG_ARGV(args->begin_argv, args->argc,
exec_args_get_begin_envv(args) - args->begin_argv);
AUDIT_ARG_ENVV(exec_args_get_begin_envv(args), args->envc,
args->endp - exec_args_get_begin_envv(args));
/* Must have at least one argument. */
if (args->argc == 0) {
exec_free_args(args);
return (EINVAL);
}
return (do_execve(td, args, mac_p, oldvmspace));
}
static void
execve_nosetid(struct image_params *imgp)
{
imgp->credential_setid = false;
if (imgp->newcred != NULL) {
crfree(imgp->newcred);
imgp->newcred = NULL;
}
}
/*
* In-kernel implementation of execve(). All arguments are assumed to be
* userspace pointers from the passed thread.
*/
static int
do_execve(struct thread *td, struct image_args *args, struct mac *mac_p,
struct vmspace *oldvmspace)
{
struct proc *p = td->td_proc;
struct nameidata nd;
struct ucred *oldcred;
struct uidinfo *euip = NULL;
uintptr_t stack_base;
struct image_params image_params, *imgp;
struct vattr attr;
struct pargs *oldargs = NULL, *newargs = NULL;
struct sigacts *oldsigacts = NULL, *newsigacts = NULL;
#ifdef KTRACE
struct ktr_io_params *kiop;
#endif
struct vnode *oldtextvp, *newtextvp;
struct vnode *oldtextdvp, *newtextdvp;
char *oldbinname, *newbinname;
bool credential_changing;
#ifdef MAC
struct label *interpvplabel = NULL;
bool will_transition;
#endif
#ifdef HWPMC_HOOKS
struct pmckern_procexec pe;
#endif
int error, i, orig_osrel;
uint32_t orig_fctl0;
Elf_Brandinfo *orig_brandinfo;
size_t freepath_size;
static const char fexecv_proc_title[] = "(fexecv)";
imgp = &image_params;
oldtextvp = oldtextdvp = NULL;
newtextvp = newtextdvp = NULL;
newbinname = oldbinname = NULL;
#ifdef KTRACE
kiop = NULL;
#endif
/*
* 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
*/
bzero(imgp, sizeof(*imgp));
imgp->proc = p;
imgp->attr = &attr;
imgp->args = args;
oldcred = p->p_ucred;
orig_osrel = p->p_osrel;
orig_fctl0 = p->p_fctl0;
orig_brandinfo = p->p_elf_brandinfo;
#ifdef MAC
error = mac_execve_enter(imgp, mac_p);
if (error)
goto exec_fail;
#endif
SDT_PROBE1(proc, , , exec, args->fname);
interpret:
if (args->fname != NULL) {
#ifdef CAPABILITY_MODE
if (CAP_TRACING(td))
ktrcapfail(CAPFAIL_NAMEI, args->fname);
/*
* 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
/*
* Translate the file name. namei() returns a vnode
* pointer in ni_vp among other things.
*/
NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW |
AUDITVNODE1 | WANTPARENT, UIO_SYSSPACE,
args->fname);
error = namei(&nd);
if (error)
goto exec_fail;
newtextvp = nd.ni_vp;
newtextdvp = nd.ni_dvp;
nd.ni_dvp = NULL;
newbinname = malloc(nd.ni_cnd.cn_namelen + 1, M_PARGS,
M_WAITOK);
memcpy(newbinname, nd.ni_cnd.cn_nameptr, nd.ni_cnd.cn_namelen);
newbinname[nd.ni_cnd.cn_namelen] = '\0';
imgp->vp = newtextvp;
/*
* Do the best to calculate the full path to the image file.
*/
if (args->fname[0] == '/') {
imgp->execpath = args->fname;
} else {
VOP_UNLOCK(imgp->vp);
freepath_size = MAXPATHLEN;
if (vn_fullpath_hardlink(newtextvp, newtextdvp,
newbinname, nd.ni_cnd.cn_namelen, &imgp->execpath,
&imgp->freepath, &freepath_size) != 0)
imgp->execpath = args->fname;
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
}
} else if (imgp->interpreter_vp) {
/*
* An image activator has already provided an open vnode
*/
newtextvp = imgp->interpreter_vp;
imgp->interpreter_vp = NULL;
if (vn_fullpath(newtextvp, &imgp->execpath,
&imgp->freepath) != 0)
imgp->execpath = args->fname;
vn_lock(newtextvp, LK_SHARED | LK_RETRY);
AUDIT_ARG_VNODE1(newtextvp);
imgp->vp = newtextvp;
} else {
AUDIT_ARG_FD(args->fd);
/*
* If the descriptors was not opened with O_PATH, then
* we require that it was opened with O_EXEC or
* O_RDONLY. In either case, exec_check_permissions()
* below checks _current_ file access mode regardless
* of the permissions additionally checked at the
* open(2).
*/
error = fgetvp_exec(td, args->fd, &cap_fexecve_rights,
&newtextvp);
if (error != 0)
goto exec_fail;
if (vn_fullpath(newtextvp, &imgp->execpath,
&imgp->freepath) != 0)
imgp->execpath = args->fname;
vn_lock(newtextvp, LK_SHARED | LK_RETRY);
AUDIT_ARG_VNODE1(newtextvp);
imgp->vp = newtextvp;
}
/*
* Check file permissions. Also 'opens' file and sets its vnode to
* text mode.
*/
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);
error = exec_map_first_page(imgp);
if (error)
goto exec_fail_dealloc;
imgp->proc->p_osrel = 0;
imgp->proc->p_fctl0 = 0;
imgp->proc->p_elf_brandinfo = NULL;
/*
* Implement image setuid/setgid.
*
* Determine new credentials before attempting image activators
* so that it can be used by process_exec handlers to determine
* credential/setid changes.
*
* Don't honor setuid/setgid if the filesystem prohibits it or if
* the process is being traced.
*
* We disable setuid/setgid/etc in capability 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 = false;
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) != 0;
credential_changing |= will_transition;
#endif
/* Don't inherit PROC_PDEATHSIG_CTL value if setuid/setgid. */
if (credential_changing)
imgp->proc->p_pdeathsig = 0;
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) {
imgp->credential_setid = true;
VOP_UNLOCK(imgp->vp);
imgp->newcred = crdup(oldcred);
if (attr.va_mode & S_ISUID) {
euip = uifind(attr.va_uid);
change_euid(imgp->newcred, euip);
}
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
if (attr.va_mode & S_ISGID)
change_egid(imgp->newcred, attr.va_gid);
/*
* 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(imgp->newcred, imgp->newcred->cr_uid);
change_svgid(imgp->newcred, imgp->newcred->cr_gid);
} else {
/*
* 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) {
VOP_UNLOCK(imgp->vp);
imgp->newcred = crdup(oldcred);
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
change_svuid(imgp->newcred, imgp->newcred->cr_uid);
change_svgid(imgp->newcred, imgp->newcred->cr_gid);
}
}
/* The new credentials are installed into the process later. */
/*
* 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.
*/
error = -1;
for (i = 0; error == -1 && execsw[i]; ++i) {
if (execsw[i]->ex_imgact == NULL)
continue;
error = (*execsw[i]->ex_imgact)(imgp);
}
if (error) {
if (error == -1)
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);
/*
* The text reference needs to be removed for scripts.
* There is a short period before we determine that
* something is a script where text reference is active.
* The vnode lock is held over this entire period
* so nothing should illegitimately be blocked.
*/
MPASS(imgp->textset);
VOP_UNSET_TEXT_CHECKED(newtextvp);
imgp->textset = false;
/* free name buffer and old vnode */
#ifdef MAC
mac_execve_interpreter_enter(newtextvp, &interpvplabel);
#endif
if (imgp->opened) {
VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td);
imgp->opened = false;
}
vput(newtextvp);
imgp->vp = newtextvp = NULL;
if (args->fname != NULL) {
if (newtextdvp != NULL) {
vrele(newtextdvp);
newtextdvp = NULL;
}
NDFREE_PNBUF(&nd);
free(newbinname, M_PARGS);
newbinname = NULL;
}
vm_object_deallocate(imgp->object);
imgp->object = NULL;
execve_nosetid(imgp);
imgp->execpath = NULL;
free(imgp->freepath, M_TEMP);
imgp->freepath = NULL;
/* set new name to that of the interpreter */
if (imgp->interpreter_vp) {
args->fname = NULL;
} else {
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);
if (disallow_high_osrel &&
P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) {
error = ENOEXEC;
uprintf("Osrel %d for image %s too high\n", p->p_osrel,
imgp->execpath != NULL ? imgp->execpath : "<unresolved>");
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
goto exec_fail_dealloc;
}
/*
* Copy out strings (args and env) and initialize stack base.
*/
error = (*p->p_sysent->sv_copyout_strings)(imgp, &stack_base);
if (error != 0) {
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
goto exec_fail_dealloc;
}
/*
* Stack setup.
*/
error = (*p->p_sysent->sv_fixup)(&stack_base, imgp);
if (error != 0) {
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
goto exec_fail_dealloc;
}
/*
* For security and other reasons, the file descriptor table cannot be
* shared after an exec.
*/
fdunshare(td);
pdunshare(td);
/* close files on exec */
fdcloseexec(td);
/*
* Malloc things before we need locks.
*/
i = exec_args_get_begin_envv(imgp->args) - 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);
}
/*
* 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.
*/
if (sigacts_shared(p->p_sigacts)) {
oldsigacts = p->p_sigacts;
newsigacts = sigacts_alloc();
sigacts_copy(newsigacts, oldsigacts);
}
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
PROC_LOCK(p);
if (oldsigacts)
p->p_sigacts = newsigacts;
/* 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(newtextvp, 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_flag2 & P2_NOTRACE_EXEC) == 0)
p->p_flag2 &= ~P2_NOTRACE;
if ((p->p_flag2 & P2_STKGAP_DISABLE_EXEC) == 0)
p->p_flag2 &= ~P2_STKGAP_DISABLE;
p->p_flag2 &= ~(P2_MEMBAR_PRIVE | P2_MEMBAR_PRIVE_SYNCORE |
P2_MEMBAR_GLOBE);
if (p->p_flag & P_PPWAIT) {
p->p_flag &= ~(P_PPWAIT | P_PPTRACE);
cv_broadcast(&p->p_pwait);
/* STOPs are no longer ignored, arrange for AST */
signotify(td);
}
if ((imgp->sysent->sv_setid_allowed != NULL &&
!(*imgp->sysent->sv_setid_allowed)(td, imgp)) ||
(p->p_flag2 & P2_NO_NEW_PRIVS) != 0)
execve_nosetid(imgp);
/*
* Implement image setuid/setgid installation.
*/
if (imgp->credential_setid) {
/*
* 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
kiop = ktrprocexec(p);
#endif
/*
* Close any file descriptors 0..2 that reference procfs,
* then make sure file descriptors 0..2 are in use.
*
* Both fdsetugidsafety() and fdcheckstd() may call functions
* taking sleepable locks, so temporarily drop our locks.
*/
PROC_UNLOCK(p);
VOP_UNLOCK(imgp->vp);
fdsetugidsafety(td);
error = fdcheckstd(td);
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
if (error != 0)
goto exec_fail_dealloc;
PROC_LOCK(p);
#ifdef MAC
if (will_transition) {
mac_vnode_execve_transition(oldcred, imgp->newcred,
imgp->vp, interpvplabel, imgp);
}
#endif
} else {
if (oldcred->cr_uid == oldcred->cr_ruid &&
oldcred->cr_gid == oldcred->cr_rgid)
p->p_flag &= ~P_SUGID;
}
/*
* Set the new credentials.
*/
if (imgp->newcred != NULL) {
proc_set_cred(p, imgp->newcred);
crfree(oldcred);
oldcred = NULL;
}
/*
* Store the vp for use in kern.proc.pathname. This vnode was
* referenced by namei() or by fexecve variant of fname handling.
*/
oldtextvp = p->p_textvp;
p->p_textvp = newtextvp;
oldtextdvp = p->p_textdvp;
p->p_textdvp = newtextdvp;
newtextdvp = NULL;
oldbinname = p->p_binname;
p->p_binname = newbinname;
newbinname = NULL;
#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;
PROC_UNLOCK(p);
#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.
*/
if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) {
VOP_UNLOCK(imgp->vp);
pe.pm_credentialschanged = credential_changing;
pe.pm_baseaddr = imgp->reloc_base;
pe.pm_dynaddr = imgp->et_dyn_addr;
PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe);
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
}
#endif
/* Set values passed into the program in registers. */
(*p->p_sysent->sv_setregs)(td, imgp, stack_base);
VOP_MMAPPED(imgp->vp);
SDT_PROBE1(proc, , , exec__success, args->fname);
exec_fail_dealloc:
if (error != 0) {
p->p_osrel = orig_osrel;
p->p_fctl0 = orig_fctl0;
p->p_elf_brandinfo = orig_brandinfo;
}
if (imgp->firstpage != NULL)
exec_unmap_first_page(imgp);
if (imgp->vp != NULL) {
if (imgp->opened)
VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td);
if (imgp->textset)
VOP_UNSET_TEXT_CHECKED(imgp->vp);
if (error != 0)
vput(imgp->vp);
else
VOP_UNLOCK(imgp->vp);
if (args->fname != NULL)
NDFREE_PNBUF(&nd);
if (newtextdvp != NULL)
vrele(newtextdvp);
free(newbinname, M_PARGS);
}
if (imgp->object != NULL)
vm_object_deallocate(imgp->object);
free(imgp->freepath, M_TEMP);
if (error == 0) {
if (p->p_ptevents & PTRACE_EXEC) {
PROC_LOCK(p);
if (p->p_ptevents & PTRACE_EXEC)
td->td_dbgflags |= TDB_EXEC;
PROC_UNLOCK(p);
}
} else {
exec_fail:
/* we're done here, clear P_INEXEC */
PROC_LOCK(p);
p->p_flag &= ~P_INEXEC;
PROC_UNLOCK(p);
SDT_PROBE1(proc, , , exec__failure, error);
}
if (imgp->newcred != NULL && oldcred != NULL)
crfree(imgp->newcred);
#ifdef MAC
mac_execve_exit(imgp);
mac_execve_interpreter_exit(interpvplabel);
#endif
exec_free_args(args);
/*
* Handle deferred decrement of ref counts.
*/
if (oldtextvp != NULL)
vrele(oldtextvp);
if (oldtextdvp != NULL)
vrele(oldtextdvp);
free(oldbinname, M_PARGS);
#ifdef KTRACE
ktr_io_params_free(kiop);
#endif
pargs_drop(oldargs);
pargs_drop(newargs);
if (oldsigacts != NULL)
sigacts_free(oldsigacts);
if (euip != NULL)
uifree(euip);
if (error && imgp->vmspace_destroyed) {
/* sorry, no more process anymore. exit gracefully */
exec_cleanup(td, oldvmspace);
exit1(td, 0, SIGABRT);
/* NOT REACHED */
}
#ifdef KTRACE
if (error == 0)
ktrprocctor(p);
#endif
/*
* We don't want cpu_set_syscall_retval() to overwrite any of
* the register values put in place by exec_setregs().
* Implementations of cpu_set_syscall_retval() will leave
* registers unmodified when returning EJUSTRETURN.
*/
return (error == 0 ? EJUSTRETURN : error);
}
void
exec_cleanup(struct thread *td, struct vmspace *oldvmspace)
{
if ((td->td_pflags & TDP_EXECVMSPC) != 0) {
KASSERT(td->td_proc->p_vmspace != oldvmspace,
("oldvmspace still used"));
vmspace_free(oldvmspace);
td->td_pflags &= ~TDP_EXECVMSPC;
}
}
int
exec_map_first_page(struct image_params *imgp)
{
vm_object_t object;
vm_page_t m;
int error;
if (imgp->firstpage != NULL)
exec_unmap_first_page(imgp);
object = imgp->vp->v_object;
if (object == NULL)
return (EACCES);
#if VM_NRESERVLEVEL > 0
if ((object->flags & OBJ_COLORED) == 0) {
VM_OBJECT_WLOCK(object);
vm_object_color(object, 0);
VM_OBJECT_WUNLOCK(object);
}
#endif
error = vm_page_grab_valid_unlocked(&m, object, 0,
VM_ALLOC_COUNT(VM_INITIAL_PAGEIN) |
VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED);
if (error != VM_PAGER_OK)
return (EIO);
imgp->firstpage = sf_buf_alloc(m, 0);
imgp->image_header = (char *)sf_buf_kva(imgp->firstpage);
return (0);
}
void
exec_unmap_first_page(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_unwire(m, PQ_ACTIVE);
}
}
void
exec_onexec_old(struct thread *td)
{
sigfastblock_clear(td);
umtx_exec(td->td_proc);
}
/*
* This is an optimization which removes the unmanaged shared page
* mapping. In combination with pmap_remove_pages(), which cleans all
* managed mappings in the process' vmspace pmap, no work will be left
* for pmap_remove(min, max).
*/
void
exec_free_abi_mappings(struct proc *p)
{
struct vmspace *vmspace;
vmspace = p->p_vmspace;
if (refcount_load(&vmspace->vm_refcnt) != 1)
return;
if (!PROC_HAS_SHP(p))
return;
pmap_remove(vmspace_pmap(vmspace), vmspace->vm_shp_base,
vmspace->vm_shp_base + p->p_sysent->sv_shared_page_len);
}
/*
* Run down the current address space and install a new one.
*/
int
exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv)
{
int error;
struct proc *p = imgp->proc;
struct vmspace *vmspace = p->p_vmspace;
struct thread *td = curthread;
vm_offset_t sv_minuser;
vm_map_t map;
imgp->vmspace_destroyed = true;
imgp->sysent = sv;
if (p->p_sysent->sv_onexec_old != NULL)
p->p_sysent->sv_onexec_old(td);
itimers_exec(p);
EVENTHANDLER_DIRECT_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 (refcount_load(&vmspace->vm_refcnt) == 1 &&
vm_map_min(map) == sv_minuser &&
vm_map_max(map) == sv->sv_maxuser &&
cpu_exec_vmspace_reuse(p, map)) {
exec_free_abi_mappings(p);
shmexit(vmspace);
pmap_remove_pages(vmspace_pmap(vmspace));
vm_map_remove(map, vm_map_min(map), vm_map_max(map));
/*
* An exec terminates mlockall(MCL_FUTURE).
* ASLR and W^X states must be re-evaluated.
*/
vm_map_lock(map);
vm_map_modflags(map, 0, MAP_WIREFUTURE | MAP_ASLR |
MAP_ASLR_IGNSTART | MAP_ASLR_STACK | MAP_WXORX);
vm_map_unlock(map);
} else {
error = vmspace_exec(p, sv_minuser, sv->sv_maxuser);
if (error)
return (error);
vmspace = p->p_vmspace;
map = &vmspace->vm_map;
}
map->flags |= imgp->map_flags;
return (sv->sv_onexec != NULL ? sv->sv_onexec(p, imgp) : 0);
}
/*
* Compute the stack size limit and map the main process stack.
* Map the shared page.
*/
int
exec_map_stack(struct image_params *imgp)
{
struct rlimit rlim_stack;
struct sysentvec *sv;
struct proc *p;
vm_map_t map;
struct vmspace *vmspace;
vm_offset_t stack_addr, stack_top;
vm_offset_t sharedpage_addr;
u_long ssiz;
int error, find_space, stack_off;
vm_prot_t stack_prot;
vm_object_t obj;
p = imgp->proc;
sv = p->p_sysent;
if (imgp->stack_sz != 0) {
ssiz = trunc_page(imgp->stack_sz);
PROC_LOCK(p);
lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack);
PROC_UNLOCK(p);
if (ssiz > rlim_stack.rlim_max)
ssiz = rlim_stack.rlim_max;
if (ssiz > rlim_stack.rlim_cur) {
rlim_stack.rlim_cur = ssiz;
kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack);
}
} else if (sv->sv_maxssiz != NULL) {
ssiz = *sv->sv_maxssiz;
} else {
ssiz = maxssiz;
}
vmspace = p->p_vmspace;
map = &vmspace->vm_map;
stack_prot = sv->sv_shared_page_obj != NULL && imgp->stack_prot != 0 ?
imgp->stack_prot : sv->sv_stackprot;
if ((map->flags & MAP_ASLR_STACK) != 0) {
stack_addr = round_page((vm_offset_t)p->p_vmspace->vm_daddr +
lim_max(curthread, RLIMIT_DATA));
find_space = VMFS_ANY_SPACE;
} else {
stack_addr = sv->sv_usrstack - ssiz;
find_space = VMFS_NO_SPACE;
}
error = vm_map_find(map, NULL, 0, &stack_addr, (vm_size_t)ssiz,
sv->sv_usrstack, find_space, stack_prot, VM_PROT_ALL,
MAP_STACK_GROWS_DOWN);
if (error != KERN_SUCCESS) {
uprintf("exec_new_vmspace: mapping stack size %#jx prot %#x "
"failed, mach error %d errno %d\n", (uintmax_t)ssiz,
stack_prot, error, vm_mmap_to_errno(error));
return (vm_mmap_to_errno(error));
}
stack_top = stack_addr + ssiz;
if ((map->flags & MAP_ASLR_STACK) != 0) {
/* Randomize within the first page of the stack. */
arc4rand(&stack_off, sizeof(stack_off), 0);
stack_top -= rounddown2(stack_off & PAGE_MASK, sizeof(void *));
}
/* Map a shared page */
obj = sv->sv_shared_page_obj;
if (obj == NULL) {
sharedpage_addr = 0;
goto out;
}
/*
* If randomization is disabled then the shared page will
* be mapped at address specified in sysentvec.
* Otherwise any address above .data section can be selected.
* Same logic is used for stack address randomization.
* If the address randomization is applied map a guard page
* at the top of UVA.
*/
vm_object_reference(obj);
if ((imgp->imgp_flags & IMGP_ASLR_SHARED_PAGE) != 0) {
sharedpage_addr = round_page((vm_offset_t)p->p_vmspace->vm_daddr +
lim_max(curthread, RLIMIT_DATA));
error = vm_map_fixed(map, NULL, 0,
sv->sv_maxuser - PAGE_SIZE, PAGE_SIZE,
VM_PROT_NONE, VM_PROT_NONE, MAP_CREATE_GUARD);
if (error != KERN_SUCCESS) {
/*
* This is not fatal, so let's just print a warning
* and continue.
*/
uprintf("%s: Mapping guard page at the top of UVA failed"
" mach error %d errno %d",
__func__, error, vm_mmap_to_errno(error));
}
error = vm_map_find(map, obj, 0,
&sharedpage_addr, sv->sv_shared_page_len,
sv->sv_maxuser, VMFS_ANY_SPACE,
VM_PROT_READ | VM_PROT_EXECUTE,
VM_PROT_READ | VM_PROT_EXECUTE,
MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
} else {
sharedpage_addr = sv->sv_shared_page_base;
vm_map_fixed(map, obj, 0,
sharedpage_addr, sv->sv_shared_page_len,
VM_PROT_READ | VM_PROT_EXECUTE,
VM_PROT_READ | VM_PROT_EXECUTE,
MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
}
if (error != KERN_SUCCESS) {
uprintf("%s: mapping shared page at addr: %p"
"failed, mach error %d errno %d\n", __func__,
(void *)sharedpage_addr, error, vm_mmap_to_errno(error));
vm_object_deallocate(obj);
return (vm_mmap_to_errno(error));
}
out:
/*
* vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they
* are still used to enforce the stack rlimit on the process stack.
*/
vmspace->vm_maxsaddr = (char *)stack_addr;
vmspace->vm_stacktop = stack_top;
vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
vmspace->vm_shp_base = sharedpage_addr;
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, const char *fname,
enum uio_seg segflg, char **argv, char **envv)
{
u_long arg, env;
int error;
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.
*/
error = exec_args_add_fname(args, fname, segflg);
if (error != 0)
goto err_exit;
/*
* extract arguments first
*/
for (;;) {
error = fueword(argv++, &arg);
if (error == -1) {
error = EFAULT;
goto err_exit;
}
if (arg == 0)
break;
error = exec_args_add_arg(args, (char *)(uintptr_t)arg,
UIO_USERSPACE);
if (error != 0)
goto err_exit;
}
/*
* extract environment strings
*/
if (envv) {
for (;;) {
error = fueword(envv++, &env);
if (error == -1) {
error = EFAULT;
goto err_exit;
}
if (env == 0)
break;
error = exec_args_add_env(args,
(char *)(uintptr_t)env, UIO_USERSPACE);
if (error != 0)
goto err_exit;
}
}
return (0);
err_exit:
exec_free_args(args);
return (error);
}
struct exec_args_kva {
vm_offset_t addr;
u_int gen;
SLIST_ENTRY(exec_args_kva) next;
};
DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva);
static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist;
static struct mtx exec_args_kva_mtx;
static u_int exec_args_gen;
static void
exec_prealloc_args_kva(void *arg __unused)
{
struct exec_args_kva *argkva;
u_int i;
SLIST_INIT(&exec_args_kva_freelist);
mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF);
for (i = 0; i < exec_map_entries; i++) {
argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK);
argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size);
argkva->gen = exec_args_gen;
SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next);
}
}
SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL);
static vm_offset_t
exec_alloc_args_kva(void **cookie)
{
struct exec_args_kva *argkva;
argkva = (void *)atomic_readandclear_ptr(
(uintptr_t *)DPCPU_PTR(exec_args_kva));
if (argkva == NULL) {
mtx_lock(&exec_args_kva_mtx);
while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL)
(void)mtx_sleep(&exec_args_kva_freelist,
&exec_args_kva_mtx, 0, "execkva", 0);
SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next);
mtx_unlock(&exec_args_kva_mtx);
}
kasan_mark((void *)argkva->addr, exec_map_entry_size,
exec_map_entry_size, 0);
*(struct exec_args_kva **)cookie = argkva;
return (argkva->addr);
}
static void
exec_release_args_kva(struct exec_args_kva *argkva, u_int gen)
{
vm_offset_t base;
base = argkva->addr;
kasan_mark((void *)argkva->addr, 0, exec_map_entry_size,
KASAN_EXEC_ARGS_FREED);
if (argkva->gen != gen) {
(void)vm_map_madvise(exec_map, base, base + exec_map_entry_size,
MADV_FREE);
argkva->gen = gen;
}
if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva),
(uintptr_t)NULL, (uintptr_t)argkva)) {
mtx_lock(&exec_args_kva_mtx);
SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next);
wakeup_one(&exec_args_kva_freelist);
mtx_unlock(&exec_args_kva_mtx);
}
}
static void
exec_free_args_kva(void *cookie)
{
exec_release_args_kva(cookie, exec_args_gen);
}
static void
exec_args_kva_lowmem(void *arg __unused)
{
SLIST_HEAD(, exec_args_kva) head;
struct exec_args_kva *argkva;
u_int gen;
int i;
gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1;
/*
* Force an madvise of each KVA range. Any currently allocated ranges
* will have MADV_FREE applied once they are freed.
*/
SLIST_INIT(&head);
mtx_lock(&exec_args_kva_mtx);
SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva);
mtx_unlock(&exec_args_kva_mtx);
while ((argkva = SLIST_FIRST(&head)) != NULL) {
SLIST_REMOVE_HEAD(&head, next);
exec_release_args_kva(argkva, gen);
}
CPU_FOREACH(i) {
argkva = (void *)atomic_readandclear_ptr(
(uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva));
if (argkva != NULL)
exec_release_args_kva(argkva, gen);
}
}
EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL,
EVENTHANDLER_PRI_ANY);
/*
* Allocate temporary demand-paged, zero-filled memory for the file name,
* argument, and environment strings.
*/
int
exec_alloc_args(struct image_args *args)
{
args->buf = (char *)exec_alloc_args_kva(&args->bufkva);
return (0);
}
void
exec_free_args(struct image_args *args)
{
if (args->buf != NULL) {
exec_free_args_kva(args->bufkva);
args->buf = NULL;
}
if (args->fname_buf != NULL) {
free(args->fname_buf, M_TEMP);
args->fname_buf = NULL;
}
}
/*
* A set to functions to fill struct image args.
*
* NOTE: exec_args_add_fname() must be called (possibly with a NULL
* fname) before the other functions. All exec_args_add_arg() calls must
* be made before any exec_args_add_env() calls. exec_args_adjust_args()
* may be called any time after exec_args_add_fname().
*
* exec_args_add_fname() - install path to be executed
* exec_args_add_arg() - append an argument string
* exec_args_add_env() - append an env string
* exec_args_adjust_args() - adjust location of the argument list to
* allow new arguments to be prepended
*/
int
exec_args_add_fname(struct image_args *args, const char *fname,
enum uio_seg segflg)
{
int error;
size_t length;
KASSERT(args->fname == NULL, ("fname already appended"));
KASSERT(args->endp == NULL, ("already appending to args"));
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)
return (error == ENAMETOOLONG ? E2BIG : error);
} else
length = 0;
/* Set up for _arg_*()/_env_*() */
args->endp = args->buf + length;
/* begin_argv must be set and kept updated */
args->begin_argv = args->endp;
KASSERT(exec_map_entry_size - length >= ARG_MAX,
("too little space remaining for arguments %zu < %zu",
exec_map_entry_size - length, (size_t)ARG_MAX));
args->stringspace = ARG_MAX;
return (0);
}
static int
exec_args_add_str(struct image_args *args, const char *str,
enum uio_seg segflg, int *countp)
{
int error;
size_t length;
KASSERT(args->endp != NULL, ("endp not initialized"));
KASSERT(args->begin_argv != NULL, ("begin_argp not initialized"));
error = (segflg == UIO_SYSSPACE) ?
copystr(str, args->endp, args->stringspace, &length) :
copyinstr(str, args->endp, args->stringspace, &length);
if (error != 0)
return (error == ENAMETOOLONG ? E2BIG : error);
args->stringspace -= length;
args->endp += length;
(*countp)++;
return (0);
}
int
exec_args_add_arg(struct image_args *args, const char *argp,
enum uio_seg segflg)
{
KASSERT(args->envc == 0, ("appending args after env"));
return (exec_args_add_str(args, argp, segflg, &args->argc));
}
int
exec_args_add_env(struct image_args *args, const char *envp,
enum uio_seg segflg)
{
if (args->envc == 0)
args->begin_envv = args->endp;
return (exec_args_add_str(args, envp, segflg, &args->envc));
}
int
exec_args_adjust_args(struct image_args *args, size_t consume, ssize_t extend)
{
ssize_t offset;
KASSERT(args->endp != NULL, ("endp not initialized"));
KASSERT(args->begin_argv != NULL, ("begin_argp not initialized"));
offset = extend - consume;
if (args->stringspace < offset)
return (E2BIG);
memmove(args->begin_argv + extend, args->begin_argv + consume,
args->endp - args->begin_argv + consume);
if (args->envc > 0)
args->begin_envv += offset;
args->endp += offset;
args->stringspace -= offset;
return (0);
}
char *
exec_args_get_begin_envv(struct image_args *args)
{
KASSERT(args->endp != NULL, ("endp not initialized"));
if (args->envc > 0)
return (args->begin_envv);
return (args->endp);
}
/*
* 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.
*/
int
exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
{
int argc, envc;
char **vectp;
char *stringp;
uintptr_t destp, ustringp;
struct ps_strings *arginfo;
struct proc *p;
struct sysentvec *sysent;
size_t execpath_len;
int error, szsigcode;
char canary[sizeof(long) * 8];
p = imgp->proc;
sysent = p->p_sysent;
destp = PROC_PS_STRINGS(p);
arginfo = imgp->ps_strings = (void *)destp;
/*
* Install sigcode.
*/
if (sysent->sv_shared_page_base == 0 && sysent->sv_szsigcode != NULL) {
szsigcode = *(sysent->sv_szsigcode);
destp -= szsigcode;
destp = rounddown2(destp, sizeof(void *));
error = copyout(sysent->sv_sigcode, (void *)destp, szsigcode);
if (error != 0)
return (error);
}
/*
* Copy the image path for the rtld.
*/
if (imgp->execpath != NULL && imgp->auxargs != NULL) {
execpath_len = strlen(imgp->execpath) + 1;
destp -= execpath_len;
destp = rounddown2(destp, sizeof(void *));
imgp->execpathp = (void *)destp;
error = copyout(imgp->execpath, imgp->execpathp, execpath_len);
if (error != 0)
return (error);
}
/*
* Prepare the canary for SSP.
*/
arc4rand(canary, sizeof(canary), 0);
destp -= sizeof(canary);
imgp->canary = (void *)destp;
error = copyout(canary, imgp->canary, sizeof(canary));
if (error != 0)
return (error);
imgp->canarylen = sizeof(canary);
/*
* Prepare the pagesizes array.
*/
imgp->pagesizeslen = sizeof(pagesizes[0]) * MAXPAGESIZES;
destp -= imgp->pagesizeslen;
destp = rounddown2(destp, sizeof(void *));
imgp->pagesizes = (void *)destp;
error = copyout(pagesizes, imgp->pagesizes, imgp->pagesizeslen);
if (error != 0)
return (error);
/*
* Allocate room for the argument and environment strings.
*/
destp -= ARG_MAX - imgp->args->stringspace;
destp = rounddown2(destp, sizeof(void *));
ustringp = destp;
if (imgp->auxargs) {
/*
* Allocate room on the stack for the ELF auxargs
* array. It has up to AT_COUNT entries.
*/
destp -= AT_COUNT * sizeof(Elf_Auxinfo);
destp = rounddown2(destp, sizeof(void *));
}
vectp = (char **)destp;
/*
* Allocate room for the argv[] and env vectors including the
* terminating NULL pointers.
*/
vectp -= imgp->args->argc + 1 + imgp->args->envc + 1;
/*
* vectp also becomes our initial stack base
*/
*stack_base = (uintptr_t)vectp;
stringp = imgp->args->begin_argv;
argc = imgp->args->argc;
envc = imgp->args->envc;
/*
* Copy out strings - arguments and environment.
*/
error = copyout(stringp, (void *)ustringp,
ARG_MAX - imgp->args->stringspace);
if (error != 0)
return (error);
/*
* Fill in "ps_strings" struct for ps, w, etc.
*/
imgp->argv = vectp;
if (suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp) != 0 ||
suword32(&arginfo->ps_nargvstr, argc) != 0)
return (EFAULT);
/*
* Fill in argument portion of vector table.
*/
for (; argc > 0; --argc) {
if (suword(vectp++, ustringp) != 0)
return (EFAULT);
while (*stringp++ != 0)
ustringp++;
ustringp++;
}
/* a null vector table pointer separates the argp's from the envp's */
if (suword(vectp++, 0) != 0)
return (EFAULT);
imgp->envv = vectp;
if (suword(&arginfo->ps_envstr, (long)(intptr_t)vectp) != 0 ||
suword32(&arginfo->ps_nenvstr, envc) != 0)
return (EFAULT);
/*
* Fill in environment portion of vector table.
*/
for (; envc > 0; --envc) {
if (suword(vectp++, ustringp) != 0)
return (EFAULT);
while (*stringp++ != 0)
ustringp++;
ustringp++;
}
/* end of vector table is a null pointer */
if (suword(vectp, 0) != 0)
return (EFAULT);
if (imgp->auxargs) {
vectp++;
error = imgp->sysent->sv_copyout_auxargs(imgp,
(uintptr_t)vectp);
if (error != 0)
return (error);
}
return (0);
}
/*
* Check permissions of file to execute.
* Called with imgp->vp locked.
* Return 0 for success or error code on failure.
*/
int
exec_check_permissions(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.
*
* Add a text reference 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.
*/
error = VOP_SET_TEXT(vp);
if (error != 0)
return (error);
imgp->textset = true;
/*
* 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 = true;
return (error);
}
/*
* Exec handler registration
*/
int
exec_register(const struct execsw *execsw_arg)
{
const struct execsw **es, **xs, **newexecsw;
u_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);
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(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);
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);
}
/*
* Write out a core segment to the compression stream.
*/
static int
compress_chunk(struct coredump_params *cp, char *base, char *buf, size_t len)
{
size_t chunk_len;
int error;
while (len > 0) {
chunk_len = MIN(len, CORE_BUF_SIZE);
/*
* We can get EFAULT error here.
* In that case zero out the current chunk of the segment.
*/
error = copyin(base, buf, chunk_len);
if (error != 0)
bzero(buf, chunk_len);
error = compressor_write(cp->comp, buf, chunk_len);
if (error != 0)
break;
base += chunk_len;
len -= chunk_len;
}
return (error);
}
int
core_write(struct coredump_params *cp, const void *base, size_t len,
off_t offset, enum uio_seg seg, size_t *resid)
{
return (vn_rdwr_inchunks(UIO_WRITE, cp->vp, __DECONST(void *, base),
len, offset, seg, IO_UNIT | IO_DIRECT | IO_RANGELOCKED,
cp->active_cred, cp->file_cred, resid, cp->td));
}
int
core_output(char *base, size_t len, off_t offset, struct coredump_params *cp,
void *tmpbuf)
{
vm_map_t map;
struct mount *mp;
size_t resid, runlen;
int error;
bool success;
KASSERT((uintptr_t)base % PAGE_SIZE == 0,
("%s: user address %p is not page-aligned", __func__, base));
if (cp->comp != NULL)
return (compress_chunk(cp, base, tmpbuf, len));
map = &cp->td->td_proc->p_vmspace->vm_map;
for (; len > 0; base += runlen, offset += runlen, len -= runlen) {
/*
* Attempt to page in all virtual pages in the range. If a
* virtual page is not backed by the pager, it is represented as
* a hole in the file. This can occur with zero-filled
* anonymous memory or truncated files, for example.
*/
for (runlen = 0; runlen < len; runlen += PAGE_SIZE) {
if (core_dump_can_intr && curproc_sigkilled())
return (EINTR);
error = vm_fault(map, (uintptr_t)base + runlen,
VM_PROT_READ, VM_FAULT_NOFILL, NULL);
if (runlen == 0)
success = error == KERN_SUCCESS;
else if ((error == KERN_SUCCESS) != success)
break;
}
if (success) {
error = core_write(cp, base, runlen, offset,
UIO_USERSPACE, &resid);
if (error != 0) {
if (error != EFAULT)
break;
/*
* EFAULT may be returned if the user mapping
* could not be accessed, e.g., because a mapped
* file has been truncated. Skip the page if no
* progress was made, to protect against a
* hypothetical scenario where vm_fault() was
* successful but core_write() returns EFAULT
* anyway.
*/
runlen -= resid;
if (runlen == 0) {
success = false;
runlen = PAGE_SIZE;
}
}
}
if (!success) {
error = vn_start_write(cp->vp, &mp, V_WAIT);
if (error != 0)
break;
vn_lock(cp->vp, LK_EXCLUSIVE | LK_RETRY);
error = vn_truncate_locked(cp->vp, offset + runlen,
false, cp->td->td_ucred);
VOP_UNLOCK(cp->vp);
vn_finished_write(mp);
if (error != 0)
break;
}
}
return (error);
}
/*
* Drain into a core file.
*/
int
sbuf_drain_core_output(void *arg, const char *data, int len)
{
struct coredump_params *cp;
struct proc *p;
int error, locked;
cp = arg;
p = cp->td->td_proc;
/*
* Some kern_proc out routines that print to this sbuf may
* call us with the process lock held. Draining with the
* non-sleepable lock held is unsafe. The lock is needed for
* those routines when dumping a live process. In our case we
* can safely release the lock before draining and acquire
* again after.
*/
locked = PROC_LOCKED(p);
if (locked)
PROC_UNLOCK(p);
if (cp->comp != NULL)
error = compressor_write(cp->comp, __DECONST(char *, data),
len);
else
error = core_write(cp, __DECONST(void *, data), len, cp->offset,
UIO_SYSSPACE, NULL);
if (locked)
PROC_LOCK(p);
if (error != 0)
return (-error);
cp->offset += len;
return (len);
}
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