ref: c5c19dfe4998fa40de5f58f61439fd5fd65c9056
dir: /sys/src/libauth/newns.c/
#include <u.h> #include <libc.h> #include <bio.h> #include <auth.h> #include <authsrv.h> #include "authlocal.h" enum { NARG = 15, /* max number of arguments */ MAXARG = 10*ANAMELEN, /* max length of an argument */ }; static int setenv(char*, char*); static char *expandarg(char*, char*); static int splitargs(char*, char*[], char*, int); static int nsfile(char*, Biobuf *, AuthRpc *, int); static int nsop(char*, int, char*[], AuthRpc*, int); static int catch(void*, char*); int newnsdebug; static int freecloserpc(AuthRpc *rpc) { if(rpc){ close(rpc->afd); auth_freerpc(rpc); } return -1; } static int buildns(int newns, char *user, char *file) { Biobuf *b; char home[4*ANAMELEN]; int afd, cdroot, dfd; char *path; AuthRpc *rpc; rpc = nil; /* try for factotum now because later is impossible */ afd = open("/mnt/factotum/rpc", ORDWR|OCEXEC); if(afd < 0 && newnsdebug) fprint(2, "open /mnt/factotum/rpc: %r\n"); if(afd >= 0){ rpc = auth_allocrpc(afd); if(rpc == nil) close(afd); } /* rpc != nil iff afd >= 0 */ dfd = open("#c/drivers", OWRITE|OCEXEC); if(dfd < 0 && newnsdebug) fprint(2, "open #c/drivers: %r\n"); if(file == nil){ if(!newns){ close(dfd); werrstr("no namespace file specified"); return freecloserpc(rpc); } file = "/lib/namespace"; } b = Bopen(file, OREAD|OCEXEC); if(b == nil){ close(dfd); werrstr("can't open %s: %r", file); return freecloserpc(rpc); } if(newns){ rfork(RFENVG|RFCNAMEG); setenv("user", user); snprint(home, sizeof home, "/usr/%s", user); setenv("home", home); } cdroot = nsfile(newns ? "newns" : "addns", b, rpc, dfd); close(dfd); Bterm(b); freecloserpc(rpc); /* make sure we managed to cd into the new name space */ if(newns && !cdroot){ path = malloc(1024); if(path == nil || getwd(path, 1024) == 0 || chdir(path) < 0) chdir("/"); if(path != nil) free(path); } return 0; } static int nsfile(char *fn, Biobuf *b, AuthRpc *rpc, int dfd) { int argc; char *cmd, *argv[NARG+1], argbuf[MAXARG*NARG]; int cdroot; cdroot = 0; atnotify(catch, 1); while(cmd = Brdline(b, '\n')){ cmd[Blinelen(b)-1] = '\0'; while(*cmd==' ' || *cmd=='\t') cmd++; if(*cmd == '#') continue; argc = splitargs(cmd, argv, argbuf, NARG); if(argc) cdroot |= nsop(fn, argc, argv, rpc, dfd); } atnotify(catch, 0); return cdroot; } int newns(char *user, char *file) { return buildns(1, user, file); } int addns(char *user, char *file) { return buildns(0, user, file); } static int famount(int fd, AuthRpc *rpc, char *mntpt, int flags, char *aname) { int afd; AuthInfo *ai; int ret; afd = fauth(fd, aname); if(afd >= 0){ ai = fauth_proxy(afd, rpc, amount_getkey, "proto=p9any role=client"); if(ai != nil) auth_freeAI(ai); } ret = mount(fd, afd, mntpt, flags, aname); if(ret == -1) close(fd); if(afd >= 0) close(afd); return ret; } static int nsop(char *fn, int argc, char *argv[], AuthRpc *rpc, int dfd) { char *argv0; ulong flags; char *devop; int fd, i; Biobuf *b; int cdroot; cdroot = 0; flags = 0; devop = "&"; argv0 = nil; if(newnsdebug){ for (i = 0; i < argc; i++) fprint(2, "%s ", argv[i]); fprint(2, "\n"); } ARGBEGIN{ case 'a': flags |= MAFTER; break; case 'b': flags |= MBEFORE; break; case 'c': flags |= MCREATE; break; case 'C': flags |= MCACHE; break; case 'r': devop = "&~"; break; case 'n': devop = "~"; break; }ARGEND if(!(flags & (MAFTER|MBEFORE))) flags |= MREPL; if(strcmp(argv0, ".") == 0 && argc == 1){ b = Bopen(argv[0], OREAD|OCEXEC); if(b == nil) return 0; cdroot |= nsfile(fn, b, rpc, dfd); Bterm(b); }else if(strcmp(argv0, "clear") == 0 && argc == 0){ rfork(RFCNAMEG); }else if(strcmp(argv0, "bind") == 0 && argc == 2){ if(bind(argv[0], argv[1], flags) == -1 && newnsdebug) fprint(2, "%s: bind: %s %s: %r\n", fn, argv[0], argv[1]); }else if(strcmp(argv0, "unmount") == 0){ if(argc == 1) unmount(nil, argv[0]); else if(argc == 2) unmount(argv[0], argv[1]); }else if(strcmp(argv0, "mount") == 0){ fd = open(argv[0], ORDWR); if(fd < 0){ if(newnsdebug) fprint(2, "%s: mount: %s: %r\n", fn, argv[0]); return 0; } if(argc == 2){ if(famount(fd, rpc, argv[1], flags, "") == -1 && newnsdebug) fprint(2, "%s: mount: %s %s: %r\n", fn, argv[0], argv[1]); }else if(argc == 3){ if(famount(fd, rpc, argv[1], flags, argv[2]) == -1 && newnsdebug) fprint(2, "%s: mount: %s %s %s: %r\n", fn, argv[0], argv[1], argv[2]); } else { close(fd); } }else if(strcmp(argv0, "cd") == 0 && argc == 1){ if(chdir(argv[0]) == 0 && *argv[0] == '/') cdroot = 1; }else if(strcmp(argv0, "chdev") == 0){ //We should not silently fail if we can not honor a chdev //due to the parent namespace missing #c/drivers. if(dfd <= 0) sysfatal("chdev requested, but could not open #c/drivers"); if(argc == 0 && devop[0] == '~'){ if(fprint(dfd, "chdev ~") < 0 && newnsdebug) fprint(2, "%s: chdev ~: %r\n", fn); }else if(argc == 1){ if(fprint(dfd, "chdev %s %s", devop, argv[0]) < 0 && newnsdebug) fprint(2, "%s: chdev %s %s: %r\n", fn, devop, argv[0]); } } return cdroot; } static char *wocp = "sys: write on closed pipe"; static int catch(void *x, char *m) { USED(x); return strncmp(m, wocp, strlen(wocp)) == 0; } static char* unquote(char *s) { char *r, *w; int inquote; inquote = 0; for(r=w=s; *r; r++){ if(*r != '\''){ *w++ = *r; continue; } if(inquote){ if(*(r+1) == '\''){ *w++ = '\''; r++; }else inquote = 0; }else inquote = 1; } *w = 0; return s; } static int splitargs(char *p, char *argv[], char *argbuf, int nargv) { char *q; int i, n; n = gettokens(p, argv, nargv, " \t\r"); if(n == nargv) return 0; for(i = 0; i < n; i++){ q = argv[i]; argv[i] = argbuf; argbuf = expandarg(q, argbuf); if(argbuf == nil) return 0; unquote(argv[i]); } return n; } static char* nextdollar(char *arg) { char *p; int inquote; inquote = 0; for(p=arg; *p; p++){ if(*p == '\'') inquote = !inquote; if(*p == '$' && !inquote) return p; } return nil; } /* * copy the arg into the buffer, * expanding any environment variables. * environment variables are assumed to be * names (ie. < ANAMELEN long) * the entire argument is expanded to be at * most MAXARG long and null terminated * the address of the byte after the terminating null is returned * any problems cause a 0 return; */ static char * expandarg(char *arg, char *buf) { char env[3+ANAMELEN], *p, *x; int fd, n, len; n = 0; while(p = nextdollar(arg)){ len = p - arg; if(n + len + ANAMELEN >= MAXARG-1) return 0; memmove(&buf[n], arg, len); n += len; p++; arg = strpbrk(p, "/.!'$"); if(arg == nil) arg = p+strlen(p); len = arg - p; if(len == 0 || len >= ANAMELEN) continue; strcpy(env, "#e/"); strncpy(env+3, p, len); env[3+len] = '\0'; fd = open(env, OREAD|OCEXEC); if(fd >= 0){ len = read(fd, &buf[n], ANAMELEN - 1); /* some singleton environment variables have trailing NULs */ /* lists separate entries with NULs; we arbitrarily take the first element */ if(len > 0){ x = memchr(&buf[n], 0, len); if(x != nil) len = x - &buf[n]; n += len; } close(fd); } } len = strlen(arg); if(n + len >= MAXARG - 1) return 0; strcpy(&buf[n], arg); return &buf[n+len+1]; } static int setenv(char *name, char *val) { int f; char ename[ANAMELEN+6]; long s; sprint(ename, "#e/%s", name); f = create(ename, OWRITE|OCEXEC, 0664); if(f < 0) return -1; s = strlen(val); if(write(f, val, s) != s){ close(f); return -1; } close(f); return 0; }