diff --git a/lib/libc/sys/execve.2 b/lib/libc/sys/execve.2 index a8f5aa14854b..1abadba13d91 100644 --- a/lib/libc/sys/execve.2 +++ b/lib/libc/sys/execve.2 @@ -1,379 +1,382 @@ .\" Copyright (c) 1980, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. .\" .\" @(#)execve.2 8.5 (Berkeley) 6/1/94 .\" $FreeBSD$ .\" -.Dd March 30, 2020 +.Dd January 26, 2022 .Dt EXECVE 2 .Os .Sh NAME .Nm execve , .Nm fexecve .Nd execute a file .Sh LIBRARY .Lb libc .Sh SYNOPSIS .In unistd.h .Ft int .Fn execve "const char *path" "char *const argv[]" "char *const envp[]" .Ft int .Fn fexecve "int fd" "char *const argv[]" "char *const envp[]" .Sh DESCRIPTION The .Fn execve system call transforms the calling process into a new process. The new process is constructed from an ordinary file, whose name is pointed to by .Fa path , called the .Em new process file . The .Fn fexecve system call is equivalent to .Fn execve except that the file to be executed is determined by the file descriptor .Fa fd instead of a .Fa path . This file is either an executable object file, or a file of data for an interpreter. An executable object file consists of an identifying header, followed by pages of data representing the initial program (text) and initialized data pages. Additional pages may be specified by the header to be initialized with zero data; see .Xr elf 5 and .Xr a.out 5 . .Pp An interpreter file begins with a line of the form: .Pp .Bd -ragged -offset indent -compact .Sy \&#! .Em interpreter .Bq Em arg .Ed .Pp When an interpreter file is .Sy execve Ap d , the system actually .Sy execve Ap s the specified .Em interpreter . If the optional .Em arg is specified, it becomes the first argument to the .Em interpreter , and the name of the originally .Sy execve Ap d file becomes the second argument; otherwise, the name of the originally .Sy execve Ap d file becomes the first argument. The original arguments are shifted over to become the subsequent arguments. The zeroth argument is set to the specified .Em interpreter . .Pp The argument .Fa argv is a pointer to a null-terminated array of character pointers to null-terminated character strings. These strings construct the argument list to be made available to the new process. At least one argument must be present in the array; by custom, the first element should be the name of the executed program (for example, the last component of .Fa path ) . .Pp The argument .Fa envp is also a pointer to a null-terminated array of character pointers to null-terminated strings. A pointer to this array is normally stored in the global variable .Va environ . These strings pass information to the new process that is not directly an argument to the command (see .Xr environ 7 ) . .Pp File descriptors open in the calling process image remain open in the new process image, except for those for which the close-on-exec flag is set (see .Xr close 2 and .Xr fcntl 2 ) . Descriptors that remain open are unaffected by .Fn execve . If any of the standard descriptors (0, 1, and/or 2) are closed at the time .Fn execve is called, and the process will gain privilege as a result of set-id semantics, those descriptors will be re-opened automatically. No programs, whether privileged or not, should assume that these descriptors will remain closed across a call to .Fn execve . .Pp Signals set to be ignored in the calling process are set to be ignored in the new process. Signals which are set to be caught in the calling process image are set to default action in the new process image. Blocked signals remain blocked regardless of changes to the signal action. The signal stack is reset to be undefined (see .Xr sigaction 2 for more information). .Pp If the set-user-ID mode bit of the new process image file is set (see .Xr chmod 2 ) , the effective user ID of the new process image is set to the owner ID of the new process image file. If the set-group-ID mode bit of the new process image file is set, the effective group ID of the new process image is set to the group ID of the new process image file. (The effective group ID is the first element of the group list.) The real user ID, real group ID and other group IDs of the new process image remain the same as the calling process image. After any set-user-ID and set-group-ID processing, the effective user ID is recorded as the saved set-user-ID, and the effective group ID is recorded as the saved set-group-ID. These values may be used in changing the effective IDs later (see .Xr setuid 2 ) . .Pp The set-ID bits are not honored if the respective file system has the .Cm nosuid option enabled or if the new process file is an interpreter file. Syscall tracing is disabled if effective IDs are changed. .Pp The new process also inherits the following attributes from the calling process: .Pp .Bl -column parent_process_ID -offset indent -compact .It process ID Ta see Xr getpid 2 .It parent process ID Ta see Xr getppid 2 .It process group ID Ta see Xr getpgrp 2 .It access groups Ta see Xr getgroups 2 .It working directory Ta see Xr chdir 2 .It root directory Ta see Xr chroot 2 .It control terminal Ta see Xr termios 4 .It resource usages Ta see Xr getrusage 2 .It interval timers Ta see Xr getitimer 2 .It resource limits Ta see Xr getrlimit 2 .It file mode mask Ta see Xr umask 2 .It signal mask Ta see Xr sigaction 2 , .Xr sigprocmask 2 .El .Pp When a program is executed as a result of an .Fn execve system call, it is entered as follows: .Bd -literal -offset indent main(argc, argv, envp) int argc; char **argv, **envp; .Ed .Pp where .Fa argc is the number of elements in .Fa argv (the ``arg count'') and .Fa argv points to the array of character pointers to the arguments themselves. .Pp The .Fn fexecve ignores the file offset of .Fa fd . Since execute permission is checked by .Fn fexecve , the file descriptor .Fa fd need not have been opened with the .Dv O_EXEC flag. However, if the file to be executed denies read permission for the process preparing to do the exec, the only way to provide the .Fa fd to .Fn fexecve is to use the .Dv O_EXEC flag when opening .Fa fd . Note that the file to be executed can not be open for writing. .Sh RETURN VALUES As the .Fn execve system call overlays the current process image with a new process image the successful call has no process to return to. If .Fn execve does return to the calling process an error has occurred; the return value will be -1 and the global variable .Va errno is set to indicate the error. .Sh ERRORS The .Fn execve system call will fail and return to the calling process if: .Bl -tag -width Er .It Bq Er ENOTDIR A component of the path prefix is not a directory. .It Bq Er ENAMETOOLONG A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters. .It Bq Er ENOEXEC When invoking an interpreted script, the length of the first line, inclusive of the .Sy \&#! prefix and terminating newline, exceeds .Dv MAXSHELLCMDLEN characters. .It Bq Er ENOENT The new process file does not exist. .It Bq Er ELOOP Too many symbolic links were encountered in translating the pathname. .It Bq Er EACCES Search permission is denied for a component of the path prefix. .It Bq Er EACCES The new process file is not an ordinary file. .It Bq Er EACCES The new process file mode denies execute permission. +.It Bq Er EINVAL +.Fa argv +did not contain at least one element. .It Bq Er ENOEXEC The new process file has the appropriate access permission, but has an invalid magic number in its header. .It Bq Er ETXTBSY The new process file is a pure procedure (shared text) file that is currently open for writing by some process. .It Bq Er ENOMEM The new process requires more virtual memory than is allowed by the imposed maximum .Pq Xr getrlimit 2 . .It Bq Er E2BIG The number of bytes in the new process' argument list is larger than the system-imposed limit. This limit is specified by the .Xr sysctl 3 MIB variable .Dv KERN_ARGMAX . .It Bq Er EFAULT The new process file is not as long as indicated by the size values in its header. .It Bq Er EFAULT The .Fa path , .Fa argv , or .Fa envp arguments point to an illegal address. .It Bq Er EIO An I/O error occurred while reading from the file system. .It Bq Er EINTEGRITY Corrupted data was detected while reading from the file system. .El .Pp In addition, the .Fn fexecve will fail and return to the calling process if: .Bl -tag -width Er .It Bq Er EBADF The .Fa fd argument is not a valid file descriptor open for executing. .El .Sh SEE ALSO .Xr ktrace 1 , .Xr _exit 2 , .Xr fork 2 , .Xr open 2 , .Xr execl 3 , .Xr exit 3 , .Xr sysctl 3 , .Xr a.out 5 , .Xr elf 5 , .Xr fdescfs 5 , .Xr environ 7 , .Xr mount 8 .Sh STANDARDS The .Fn execve system call conforms to .St -p1003.1-2001 , with the exception of reopening descriptors 0, 1, and/or 2 in certain circumstances. A future update of the Standard is expected to require this behavior, and it may become the default for non-privileged processes as well. .\" NB: update this caveat when TC1 is blessed. The support for executing interpreted programs is an extension. The .Fn fexecve system call conforms to The Open Group Extended API Set 2 specification. .Sh HISTORY The .Fn execve system call appeared in .At v7 . The .Fn fexecve system call appeared in .Fx 8.0 . .Sh CAVEATS If a program is .Em setuid to a non-super-user, but is executed when the real .Em uid is ``root'', then the program has some of the powers of a super-user as well. .Pp When executing an interpreted program through .Fn fexecve , kernel supplies .Pa /dev/fd/n as a second argument to the interpreter, where .Ar n is the file descriptor passed in the .Fa fd argument to .Fn fexecve . For this construction to work correctly, the .Xr fdescfs 5 filesystem shall be mounted on .Pa /dev/fd . diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c index 0494b73fc405..303c145689ae 100644 --- a/sys/kern/kern_exec.c +++ b/sys/kern/kern_exec.c @@ -1,2040 +1,2046 @@ /*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * 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 __FBSDID("$FreeBSD$"); #include "opt_capsicum.h" #include "opt_hwpmc_hooks.h" #include "opt_ktrace.h" #include "opt_vm.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef KTRACE #include #endif #include #include #include #include #include #include #include #include #include #ifdef HWPMC_HOOKS #include #endif #include #include #ifdef KDTRACE_HOOKS #include 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; int (*img_first)(struct image_params *); 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 /* * 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 | SAVENAME | 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 { 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. */ /* * 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) 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(&nd, NDF_ONLY_PNBUF); 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 */ 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 : ""); 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; 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_entryaddr = imgp->entry_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(&nd, NDF_ONLY_PNBUF); 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; struct sysentvec *sv; vmspace = p->p_vmspace; if (refcount_load(&vmspace->vm_refcnt) != 1) return; sv = p->p_sysent; if (sv->sv_shared_page_obj == NULL) return; pmap_remove(vmspace_pmap(vmspace), sv->sv_shared_page_base, sv->sv_shared_page_base + sv->sv_shared_page_len); } /* * Run down the current address space and install a new one. Map the shared * page. */ 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_object_t obj; 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; /* 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_READ | VM_PROT_EXECUTE, MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); if (error != KERN_SUCCESS) { vm_object_deallocate(obj); return (vm_mmap_to_errno(error)); } } return (sv->sv_onexec != NULL ? sv->sv_onexec(p, imgp) : 0); } /* * Compute the stack size limit and map the main process stack. */ 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; u_long ssiz; int error, find_space, stack_off; vm_prot_t stack_prot; 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 *)); } /* * 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; 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_sigcode_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); }