Remove a needlessly clever hack to start init with sys_exec().
Construct a struct image_args with the help of new exec_args_*() helper functions and call kern_execve(). The previous code mapped a page in userspace, copied arguments out to it one at a time, and then constructed a struct execve_args all so that sys_execve() can call exec_copyin_args() to copy the data back in to a struct image_args. Opencode the part of pre_execve()/post_execve() that releases a reference to the initial vmspace. We don't need to stop threads like they do. Reviewed by: kib, jhb (prior version) Obtained from: CheriBSD Sponsored by: DARPA, AFRL Differential Revision: https://reviews.freebsd.org/D15469
This commit is contained in:
Brooks Davis
parent
a66732de4f
commit
3a325dec32
@ -56,6 +56,7 @@ __FBSDID("$FreeBSD$");
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#include <sys/exec.h>
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#include <sys/file.h>
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#include <sys/filedesc.h>
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#include <sys/imgact.h>
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#include <sys/jail.h>
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#include <sys/ktr.h>
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#include <sys/lock.h>
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@ -716,15 +717,15 @@ SYSCTL_INT(_kern, OID_AUTO, init_shutdown_timeout,
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static void
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start_init(void *dummy)
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{
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vm_offset_t addr;
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struct execve_args args;
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struct image_args args;
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int options, error;
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size_t pathlen;
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char flags[8], *flagp;
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char *var, *path;
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char *free_init_path, *tmp_init_path;
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char *ucp, **uap, *arg0, *arg1;
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struct thread *td;
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struct proc *p;
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struct vmspace *oldvmspace;
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TSENTER(); /* Here so we don't overlap with mi_startup. */
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@ -736,16 +737,6 @@ start_init(void *dummy)
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/* Wipe GELI passphrase from the environment. */
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kern_unsetenv("kern.geom.eli.passphrase");
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/*
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* Need just enough stack to hold the faked-up "execve()" arguments.
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*/
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addr = p->p_sysent->sv_usrstack - PAGE_SIZE;
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if (vm_map_find(&p->p_vmspace->vm_map, NULL, 0, &addr, PAGE_SIZE, 0,
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VMFS_NO_SPACE, VM_PROT_ALL, VM_PROT_ALL, 0) != 0)
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panic("init: couldn't allocate argument space");
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p->p_vmspace->vm_maxsaddr = (caddr_t)addr;
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p->p_vmspace->vm_ssize = 1;
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if ((var = kern_getenv("init_path")) != NULL) {
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strlcpy(init_path, var, sizeof(init_path));
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freeenv(var);
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@ -757,54 +748,44 @@ start_init(void *dummy)
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if (bootverbose)
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printf("start_init: trying %s\n", path);
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/*
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* Move out the boot flag argument.
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*/
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memset(&args, 0, sizeof(args));
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error = exec_alloc_args(&args);
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if (error != 0)
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panic("%s: Can't allocate space for init arguments %d",
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__func__, error);
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error = exec_args_add_fname(&args, path, UIO_SYSSPACE);
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if (error != 0)
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panic("%s: Can't add fname %d", __func__, error);
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error = exec_args_add_arg(&args, path, UIO_SYSSPACE);
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if (error != 0)
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panic("%s: Can't add argv[0] %d", __func__, error);
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options = 0;
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ucp = (char *)p->p_sysent->sv_usrstack;
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(void)subyte(--ucp, 0); /* trailing zero */
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flagp = &flags[0];
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*flagp++ = '-';
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if (boothowto & RB_SINGLE) {
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(void)subyte(--ucp, 's');
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options = 1;
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*flagp++ = 's';
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options++;
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}
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#ifdef notyet
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if (boothowto & RB_FASTBOOT) {
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(void)subyte(--ucp, 'f');
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options = 1;
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*flagp++ = 'f';
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options++;
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}
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#endif
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#ifdef BOOTCDROM
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(void)subyte(--ucp, 'C');
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options = 1;
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*flagp++ = 'C';
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options++;
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#endif
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if (options == 0)
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(void)subyte(--ucp, '-');
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(void)subyte(--ucp, '-'); /* leading hyphen */
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arg1 = ucp;
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/*
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* Move out the file name (also arg 0).
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*/
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ucp -= pathlen;
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copyout(path, ucp, pathlen);
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arg0 = ucp;
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/*
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* Move out the arg pointers.
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*/
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uap = (char **)rounddown2((intptr_t)ucp, sizeof(intptr_t));
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(void)suword((caddr_t)--uap, (long)0); /* terminator */
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(void)suword((caddr_t)--uap, (long)(intptr_t)arg1);
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(void)suword((caddr_t)--uap, (long)(intptr_t)arg0);
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/*
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* Point at the arguments.
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*/
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args.fname = arg0;
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args.argv = uap;
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args.envv = NULL;
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*flagp++ = '-';
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*flagp++ = 0;
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KASSERT(flagp <= &flags[0] + sizeof(flags), ("Overran flags"));
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error = exec_args_add_arg(&args, flags, UIO_SYSSPACE);
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if (error != 0)
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panic("%s: Can't add argv[0] %d", __func__, error);
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/*
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* Now try to exec the program. If can't for any reason
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@ -813,7 +794,19 @@ start_init(void *dummy)
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* Otherwise, return via fork_trampoline() all the way
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* to user mode as init!
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*/
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if ((error = sys_execve(td, &args)) == EJUSTRETURN) {
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KASSERT((td->td_pflags & TDP_EXECVMSPC) == 0,
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("nested execve"));
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oldvmspace = td->td_proc->p_vmspace;
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error = kern_execve(td, &args, NULL);
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KASSERT(error != 0,
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("kern_execve returned success, not EJUSTRETURN"));
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if (error == EJUSTRETURN) {
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if ((td->td_pflags & TDP_EXECVMSPC) != 0) {
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KASSERT(p->p_vmspace != oldvmspace,
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("oldvmspace still used"));
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vmspace_free(oldvmspace);
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td->td_pflags &= ~TDP_EXECVMSPC;
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}
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free(free_init_path, M_TEMP);
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TSEXIT();
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return;
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