* "A ship then new they built for him/of mithril and of elven glass" --Bilbo
*/
+/* PSz 12 Nov 03
+ *
+ * Be proud that perl(1) may proclaim:
+ * Setuid Perl scripts are safer than C programs ...
+ * Do not abandon (deprecate) suidperl. Do not advocate C wrappers.
+ *
+ * The flow was: perl starts, notices script is suid, execs suidperl with same
+ * arguments; suidperl opens script, checks many things, sets itself with
+ * right UID, execs perl with similar arguments but with script pre-opened on
+ * /dev/fd/xxx; perl checks script is as should be and does work. This was
+ * insecure: see perlsec(1) for many problems with this approach.
+ *
+ * The "correct" flow should be: perl starts, opens script and notices it is
+ * suid, checks many things, execs suidperl with similar arguments but with
+ * script on /dev/fd/xxx; suidperl checks script and /dev/fd/xxx object are
+ * same, checks arguments match #! line, sets itself with right UID, execs
+ * perl with same arguments; perl checks many things and does work.
+ *
+ * (Opening the script in perl instead of suidperl, we "lose" scripts that
+ * are readable to the target UID but not to the invoker. Where did
+ * unreadable scripts work anyway?)
+ *
+ * For now, suidperl and perl are pretty much the same large and cumbersome
+ * program, so suidperl can check its argument list (see comments elsewhere).
+ *
+ * References:
+ * Original bug report:
+ * http://bugs.perl.org/index.html?req=bug_id&bug_id=20010322.218
+ * http://rt.perl.org/rt2/Ticket/Display.html?id=6511
+ * Comments and discussion with Debian:
+ * http://bugs.debian.org/203426
+ * http://bugs.debian.org/220486
+ * Debian Security Advisory DSA 431-1 (does not fully fix problem):
+ * http://www.debian.org/security/2004/dsa-431
+ * CVE candidate:
+ * http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0618
+ * Previous versions of this patch sent to perl5-porters:
+ * http://www.mail-archive.com/perl5-porters@perl.org/msg71953.html
+ * http://www.mail-archive.com/perl5-porters@perl.org/msg75245.html
+ * http://www.mail-archive.com/perl5-porters@perl.org/msg75563.html
+ * http://www.mail-archive.com/perl5-porters@perl.org/msg75635.html
+ *
+Paul Szabo - psz@maths.usyd.edu.au http://www.maths.usyd.edu.au:8000/u/psz/
+School of Mathematics and Statistics University of Sydney 2006 Australia
+ *
+ */
+/* PSz 13 Nov 03
+ * Use truthful, neat, specific error messages.
+ * Cannot always hide the truth; security must not depend on doing so.
+ */
+
+/* PSz 18 Feb 04
+ * Use global(?), thread-local fdscript for easier checks.
+ * (I do not understand how we could possibly get a thread race:
+ * do not all threads go through the same initialization? Or in
+ * fact, are not threads started only after we get the script and
+ * so know what to do? Oh well, make things super-safe...)
+ */
+
#include "EXTERN.h"
#define PERL_IN_PERL_C
#include "perl.h"
#ifndef DOSUID
#define DOSUID
#endif
-#endif
+#endif /* IAMSUID */
#ifdef SETUID_SCRIPTS_ARE_SECURE_NOW
#ifdef DOSUID
#undef IAMSUID
Perl_croak(aTHX_ "suidperl is no longer needed since the kernel can now execute\n\
setuid perl scripts securely.\n");
-#endif
+#endif /* IAMSUID */
#endif
#if defined(USE_HASH_SEED) || defined(USE_HASH_SEED_EXPLICIT)
int argc = PL_origargc;
char **argv = PL_origargv;
char *scriptname = NULL;
- int fdscript = -1;
VOL bool dosearch = FALSE;
char *validarg = "";
register SV *sv;
register char *s;
char *cddir = Nullch;
+/* PSz 18 Feb 04 fdscript now global, keep from confusion */
+ int dummy_fdscript = -1;
+ PL_fdscript = -1;
+ PL_suidscript = -1;
sv_setpvn(PL_linestr,"",0);
sv = newSVpvn("",0); /* first used for -I flags */
SAVEFREESV(sv);
validarg = " PHOOEY ";
else
validarg = argv[0];
+ /*
+ * Can we rely on the kernel to start scripts with argv[1] set to
+ * contain all #! line switches (the whole line)? (argv[0] is set to
+ * the interpreter name, argv[2] to the script name; argv[3] and
+ * above may contain other arguments.)
+ */
#endif
s = argv[0]+1;
reswitch:
if (argv[1] && !strcmp(argv[1], "Dev:Pseudo"))
break;
#endif
- if (PL_euid != PL_uid || PL_egid != PL_gid)
- Perl_croak(aTHX_ "No -e allowed in setuid scripts");
+ forbid_setid("-e");
if (!PL_e_script) {
PL_e_script = newSVpvn("",0);
filter_add(read_e_script, NULL);
init_perllib();
- open_script(scriptname,dosearch,sv,&fdscript);
+ open_script(scriptname,dosearch,sv,&dummy_fdscript);
- validate_suid(validarg, scriptname,fdscript);
+ validate_suid(validarg, scriptname,dummy_fdscript);
#ifndef PERL_MICRO
#if defined(SIGCHLD) || defined(SIGCLD)
sv_setpvn(get_sv("/", TRUE), "\n", 1);
}
+/* PSz 18 Nov 03 fdscript now global but do not change prototype */
STATIC void
-S_open_script(pTHX_ char *scriptname, bool dosearch, SV *sv, int *fdscript)
+S_open_script(pTHX_ char *scriptname, bool dosearch, SV *sv, int *dummy_fdscript)
{
+#ifndef IAMSUID
char *quote;
char *code;
char *cpp_discard_flag;
char *perl;
+#endif
- *fdscript = -1;
+ PL_fdscript = -1;
+ PL_suidscript = -1;
if (PL_e_script) {
PL_origfilename = savepv("-e");
if (strnEQ(scriptname, "/dev/fd/", 8) && isDIGIT(scriptname[8]) ) {
char *s = scriptname + 8;
- *fdscript = atoi(s);
+ PL_fdscript = atoi(s);
while (isDIGIT(*s))
s++;
if (*s) {
+ /* PSz 18 Feb 04
+ * Tell apart "normal" usage of fdscript, e.g.
+ * with bash on FreeBSD:
+ * perl <( echo '#!perl -DA'; echo 'print "$0\n"')
+ * from usage in suidperl.
+ * Does any "normal" usage leave garbage after the number???
+ * Is it a mistake to use a similar /dev/fd/ construct for
+ * suidperl?
+ */
+ PL_suidscript = 1;
+ /* PSz 20 Feb 04
+ * Be supersafe and do some sanity-checks.
+ * Still, can we be sure we got the right thing?
+ */
+ if (*s != '/') {
+ Perl_croak(aTHX_ "Wrong syntax (suid) fd script name \"%s\"\n", s);
+ }
+ if (! *(s+1)) {
+ Perl_croak(aTHX_ "Missing (suid) fd script name\n");
+ }
scriptname = savepv(s + 1);
Safefree(PL_origfilename);
PL_origfilename = scriptname;
CopFILE_set(PL_curcop, PL_origfilename);
if (strEQ(PL_origfilename,"-"))
scriptname = "";
- if (*fdscript >= 0) {
- PL_rsfp = PerlIO_fdopen(*fdscript,PERL_SCRIPT_MODE);
+ if (PL_fdscript >= 0) {
+ PL_rsfp = PerlIO_fdopen(PL_fdscript,PERL_SCRIPT_MODE);
# if defined(HAS_FCNTL) && defined(F_SETFD)
if (PL_rsfp)
/* ensure close-on-exec */
fcntl(PerlIO_fileno(PL_rsfp),F_SETFD,1);
# endif
}
+#ifdef IAMSUID
+ else {
+ Perl_croak(aTHX_ "suidperl needs fd script\n");
+/* PSz 11 Nov 03
+ * Do not open (or do other fancy stuff) while setuid.
+ * Perl does the open, and hands script to suidperl on a fd;
+ * suidperl only does some checks, sets up UIDs and re-execs
+ * perl with that fd as it has always done.
+ */
+ }
+ if (PL_suidscript != 1) {
+ Perl_croak(aTHX_ "suidperl needs (suid) fd script\n");
+ }
+#else /* IAMSUID */
else if (PL_preprocess) {
char *cpp_cfg = CPPSTDIN;
SV *cpp = newSVpvn("",0);
cpp_discard_flag, sv, CPPMINUS);
PL_doextract = FALSE;
-# ifdef IAMSUID /* actually, this is caught earlier */
- if (PL_euid != PL_uid && !PL_euid) { /* if running suidperl */
-# ifdef HAS_SETEUID
- (void)seteuid(PL_uid); /* musn't stay setuid root */
-# else
-# ifdef HAS_SETREUID
- (void)setreuid((Uid_t)-1, PL_uid);
-# else
-# ifdef HAS_SETRESUID
- (void)setresuid((Uid_t)-1, PL_uid, (Uid_t)-1);
-# else
- PerlProc_setuid(PL_uid);
-# endif
-# endif
-# endif
- if (PerlProc_geteuid() != PL_uid)
- Perl_croak(aTHX_ "Can't do seteuid!\n");
- }
-# endif /* IAMSUID */
DEBUG_P(PerlIO_printf(Perl_debug_log,
"PL_preprocess: cmd=\"%s\"\n",
fcntl(PerlIO_fileno(PL_rsfp),F_SETFD,1);
# endif
}
+#endif /* IAMSUID */
if (!PL_rsfp) {
-# ifdef DOSUID
-# ifndef IAMSUID /* in case script is not readable before setuid */
- if (PL_euid &&
- PerlLIO_stat(CopFILE(PL_curcop),&PL_statbuf) >= 0 &&
- PL_statbuf.st_mode & (S_ISUID|S_ISGID))
- {
- /* try again */
- PERL_FPU_PRE_EXEC
- PerlProc_execv(Perl_form(aTHX_ "%s/sperl"PERL_FS_VER_FMT,
- BIN_EXP, (int)PERL_REVISION,
- (int)PERL_VERSION,
- (int)PERL_SUBVERSION), PL_origargv);
- PERL_FPU_POST_EXEC
- Perl_croak(aTHX_ "Can't do setuid\n");
- }
-# endif
-# endif
-# ifdef IAMSUID
- errno = EPERM;
- Perl_croak(aTHX_ "Permission denied\n");
-# else
+/* PSz 16 Sep 03 Keep neat error message */
Perl_croak(aTHX_ "Can't open perl script \"%s\": %s\n",
CopFILE(PL_curcop), Strerror(errno));
-# endif
}
}
STATIC int
S_fd_on_nosuid_fs(pTHX_ int fd)
{
+/* PSz 27 Feb 04
+ * We used to do this as "plain" user (after swapping UIDs with setreuid);
+ * but is needed also on machines without setreuid.
+ * Seems safe enough to run as root.
+ */
int check_okay = 0; /* able to do all the required sys/libcalls */
int on_nosuid = 0; /* the fd is on a nosuid fs */
+ /* PSz 12 Nov 03
+ * Need to check noexec also: nosuid might not be set, the average
+ * sysadmin would say that nosuid is irrelevant once he sets noexec.
+ */
+ int on_noexec = 0; /* the fd is on a noexec fs */
+
/*
* Preferred order: fstatvfs(), fstatfs(), ustat()+getmnt(), getmntent().
* fstatvfs() is UNIX98.
check_okay = fstatvfs(fd, &stfs) == 0;
on_nosuid = check_okay && (stfs.f_flag & ST_NOSUID);
+#ifdef ST_NOEXEC
+ /* ST_NOEXEC certainly absent on AIX 5.1, and doesn't seem to be documented
+ on platforms where it is present. */
+ on_noexec = check_okay && (stfs.f_flag & ST_NOEXEC);
+#endif
# endif /* fstatvfs */
# if !defined(FD_ON_NOSUID_CHECK_OKAY) && \
defined(PERL_MOUNT_NOSUID) && \
+ defined(PERL_MOUNT_NOEXEC) && \
defined(HAS_FSTATFS) && \
defined(HAS_STRUCT_STATFS) && \
defined(HAS_STRUCT_STATFS_F_FLAGS)
check_okay = fstatfs(fd, &stfs) == 0;
on_nosuid = check_okay && (stfs.f_flags & PERL_MOUNT_NOSUID);
+ on_noexec = check_okay && (stfs.f_flags & PERL_MOUNT_NOEXEC);
# endif /* fstatfs */
# if !defined(FD_ON_NOSUID_CHECK_OKAY) && \
defined(PERL_MOUNT_NOSUID) && \
+ defined(PERL_MOUNT_NOEXEC) && \
defined(HAS_FSTAT) && \
defined(HAS_USTAT) && \
defined(HAS_GETMNT) && \
fdst.st_dev == fsd.fd_req.dev) {
check_okay = 1;
on_nosuid = fsd.fd_req.flags & PERL_MOUNT_NOSUID;
+ on_noexec = fsd.fd_req.flags & PERL_MOUNT_NOEXEC;
}
}
}
# if !defined(FD_ON_NOSUID_CHECK_OKAY) && \
defined(HAS_GETMNTENT) && \
defined(HAS_HASMNTOPT) && \
- defined(MNTOPT_NOSUID)
+ defined(MNTOPT_NOSUID) && \
+ defined(MNTOPT_NOEXEC)
# define FD_ON_NOSUID_CHECK_OKAY
FILE *mtab = fopen("/etc/mtab", "r");
struct mntent *entry;
check_okay = 1;
if (hasmntopt(entry, MNTOPT_NOSUID))
on_nosuid = 1;
+ if (hasmntopt(entry, MNTOPT_NOEXEC))
+ on_noexec = 1;
break;
} /* A single fs may well fail its stat(). */
}
# endif /* getmntent+hasmntopt */
if (!check_okay)
- Perl_croak(aTHX_ "Can't check filesystem of script \"%s\" for nosuid", PL_origfilename);
- return on_nosuid;
+ Perl_croak(aTHX_ "Can't check filesystem of script \"%s\" for nosuid/noexec", PL_origfilename);
+ if (on_nosuid)
+ Perl_croak(aTHX_ "Setuid script \"%s\" on nosuid filesystem", PL_origfilename);
+ if (on_noexec)
+ Perl_croak(aTHX_ "Setuid script \"%s\" on noexec filesystem", PL_origfilename);
+ return ((!check_okay) || on_nosuid || on_noexec);
}
#endif /* IAMSUID */
+/* PSz 18 Nov 03 fdscript now global but do not change prototype */
STATIC void
-S_validate_suid(pTHX_ char *validarg, char *scriptname, int fdscript)
+S_validate_suid(pTHX_ char *validarg, char *scriptname, int dummy_fdscript)
{
#ifdef IAMSUID
- int which;
-#endif
+ /* int which; */
+#endif /* IAMSUID */
/* do we need to emulate setuid on scripts? */
* uid. We don't just make perl setuid root because that loses the
* effective uid we had before invoking perl, if it was different from the
* uid.
+ * PSz 27 Feb 04
+ * Description/comments above do not match current workings:
+ * suidperl must be hardlinked to sperlN.NNN (that is what we exec);
+ * suidperl called with script open and name changed to /dev/fd/N/X;
+ * suidperl croaks if script is not setuid;
+ * making perl setuid would be a huge security risk (and yes, that
+ * would lose any euid we might have had).
*
* DOSUID must be defined in both perl and suidperl, and IAMSUID must
* be defined in suidperl only. suidperl must be setuid root. The
if (PerlLIO_fstat(PerlIO_fileno(PL_rsfp),&PL_statbuf) < 0) /* normal stat is insecure */
Perl_croak(aTHX_ "Can't stat script \"%s\"",PL_origfilename);
- if (fdscript < 0 && PL_statbuf.st_mode & (S_ISUID|S_ISGID)) {
+ if (PL_statbuf.st_mode & (S_ISUID|S_ISGID)) {
I32 len;
STRLEN n_a;
#ifdef IAMSUID
-#ifndef HAS_SETREUID
+ if (PL_fdscript < 0 || PL_suidscript != 1)
+ Perl_croak(aTHX_ "Need (suid) fdscript in suidperl\n"); /* We already checked this */
+ /* PSz 11 Nov 03
+ * Since the script is opened by perl, not suidperl, some of these
+ * checks are superfluous. Leaving them in probably does not lower
+ * security(?!).
+ */
+ /* PSz 27 Feb 04
+ * Do checks even for systems with no HAS_SETREUID.
+ * We used to swap, then re-swap UIDs with
+#ifdef HAS_SETREUID
+ if (setreuid(PL_euid,PL_uid) < 0
+ || PerlProc_getuid() != PL_euid || PerlProc_geteuid() != PL_uid)
+ Perl_croak(aTHX_ "Can't swap uid and euid");
+#endif
+#ifdef HAS_SETREUID
+ if (setreuid(PL_uid,PL_euid) < 0
+ || PerlProc_getuid() != PL_uid || PerlProc_geteuid() != PL_euid)
+ Perl_croak(aTHX_ "Can't reswap uid and euid");
+#endif
+ */
+
/* On this access check to make sure the directories are readable,
* there is actually a small window that the user could use to make
* filename point to an accessible directory. So there is a faint
* non-accessible directory. I don't know what to do about that.
* But I don't think it's too important. The manual lies when
* it says access() is useful in setuid programs.
+ *
+ * So, access() is pretty useless... but not harmful... do anyway.
*/
if (PerlLIO_access(CopFILE(PL_curcop),1)) { /*double check*/
- errno = EPERM;
- Perl_croak(aTHX_ "Permission denied\n");
+ Perl_croak(aTHX_ "Can't access() script\n");
}
-#else
+
/* If we can swap euid and uid, then we can determine access rights
* with a simple stat of the file, and then compare device and
* inode to make sure we did stat() on the same file we opened.
* Then we just have to make sure he or she can execute it.
+ *
+ * PSz 24 Feb 04
+ * As the script is opened by perl, not suidperl, we do not need to
+ * care much about access rights.
+ *
+ * The 'script changed' check is needed, or we can get lied to
+ * about $0 with e.g.
+ * suidperl /dev/fd/4//bin/x 4<setuidscript
+ * Without HAS_SETREUID, is it safe to stat() as root?
+ *
+ * Are there any operating systems that pass /dev/fd/xxx for setuid
+ * scripts, as suggested/described in perlsec(1)? Surely they do not
+ * pass the script name as we do, so the "script changed" test would
+ * fail for them... but we never get here with
+ * SETUID_SCRIPTS_ARE_SECURE_NOW defined.
+ *
+ * This is one place where we must "lie" about return status: not
+ * say if the stat() failed. We are doing this as root, and could
+ * be tricked into reporting existence or not of files that the
+ * "plain" user cannot even see.
*/
{
Stat_t tmpstatbuf;
-
- if (
-#ifdef HAS_SETREUID
- setreuid(PL_euid,PL_uid) < 0
-#else
-# if HAS_SETRESUID
- setresuid(PL_euid,PL_uid,(Uid_t)-1) < 0
-# endif
-#endif
- || PerlProc_getuid() != PL_euid || PerlProc_geteuid() != PL_uid)
- Perl_croak(aTHX_ "Can't swap uid and euid"); /* really paranoid */
- if (PerlLIO_stat(CopFILE(PL_curcop),&tmpstatbuf) < 0) {
- errno = EPERM;
- Perl_croak(aTHX_ "Permission denied\n"); /* testing full pathname here */
- }
-#if defined(IAMSUID) && !defined(NO_NOSUID_CHECK)
- if (fd_on_nosuid_fs(PerlIO_fileno(PL_rsfp))) {
- errno = EPERM;
- Perl_croak(aTHX_ "Permission denied\n");
- }
-#endif
- if (tmpstatbuf.st_dev != PL_statbuf.st_dev ||
+ if (PerlLIO_stat(CopFILE(PL_curcop),&tmpstatbuf) < 0 ||
+ tmpstatbuf.st_dev != PL_statbuf.st_dev ||
tmpstatbuf.st_ino != PL_statbuf.st_ino) {
- (void)PerlIO_close(PL_rsfp);
- errno = EPERM;
- Perl_croak(aTHX_ "Permission denied\n");
+ Perl_croak(aTHX_ "Setuid script changed\n");
}
- if (
-#ifdef HAS_SETREUID
- setreuid(PL_uid,PL_euid) < 0
-#else
-# if defined(HAS_SETRESUID)
- setresuid(PL_uid,PL_euid,(Uid_t)-1) < 0
-# endif
-#endif
- || PerlProc_getuid() != PL_uid || PerlProc_geteuid() != PL_euid)
- Perl_croak(aTHX_ "Can't reswap uid and euid");
- if (!cando(S_IXUSR,FALSE,&PL_statbuf)) /* can real uid exec? */
- Perl_croak(aTHX_ "Permission denied\n");
+
}
-#endif /* HAS_SETREUID */
+ if (!cando(S_IXUSR,FALSE,&PL_statbuf)) /* can real uid exec? */
+ Perl_croak(aTHX_ "Real UID cannot exec script\n");
+
+ /* PSz 27 Feb 04
+ * We used to do this check as the "plain" user (after swapping
+ * UIDs). But the check for nosuid and noexec filesystem is needed,
+ * and should be done even without HAS_SETREUID. (Maybe those
+ * operating systems do not have such mount options anyway...)
+ * Seems safe enough to do as root.
+ */
+#if !defined(NO_NOSUID_CHECK)
+ if (fd_on_nosuid_fs(PerlIO_fileno(PL_rsfp))) {
+ Perl_croak(aTHX_ "Setuid script on nosuid or noexec filesystem\n");
+ }
+#endif
#endif /* IAMSUID */
if (!S_ISREG(PL_statbuf.st_mode)) {
- errno = EPERM;
- Perl_croak(aTHX_ "Permission denied\n");
+ Perl_croak(aTHX_ "Setuid script not plain file\n");
}
if (PL_statbuf.st_mode & S_IWOTH)
Perl_croak(aTHX_ "Setuid/gid script is writable by world");
PL_doswitches = FALSE; /* -s is insecure in suid */
+ /* PSz 13 Nov 03 But -s was caught elsewhere ... so unsetting it here is useless(?!) */
CopLINE_inc(PL_curcop);
if (sv_gets(PL_linestr, PL_rsfp, 0) == Nullch ||
strnNE(SvPV(PL_linestr,n_a),"#!",2) ) /* required even on Sys V */
Perl_croak(aTHX_ "No #! line");
s = SvPV(PL_linestr,n_a)+2;
- if (*s == ' ') s++;
- while (!isSPACE(*s)) s++;
+ /* PSz 27 Feb 04 */
+ /* Sanity check on line length */
+ if (strlen(s) < 1 || strlen(s) > 4000)
+ Perl_croak(aTHX_ "Very long #! line");
+ /* Allow more than a single space after #! */
+ while (isSPACE(*s)) s++;
+ /* Sanity check on buffer end */
+ while ((*s) && !isSPACE(*s)) s++;
for (s2 = s; (s2 > SvPV(PL_linestr,n_a)+2 &&
(isDIGIT(s2[-1]) || strchr("._-", s2[-1]))); s2--) ;
- if (strnNE(s2-4,"perl",4) && strnNE(s-9,"perl",4)) /* sanity check */
+ /* Sanity check on buffer start */
+ if ( (s2-4 < SvPV(PL_linestr,n_a)+2 || strnNE(s2-4,"perl",4)) &&
+ (s-9 < SvPV(PL_linestr,n_a)+2 || strnNE(s-9,"perl",4)) )
Perl_croak(aTHX_ "Not a perl script");
while (*s == ' ' || *s == '\t') s++;
/*
* mentioning suidperl explicitly, but they may not add any strange
* arguments beyond what #! says if they do invoke suidperl that way.
*/
+ /*
+ * The way validarg was set up, we rely on the kernel to start
+ * scripts with argv[1] set to contain all #! line switches (the
+ * whole line).
+ */
+ /*
+ * Check that we got all the arguments listed in the #! line (not
+ * just that there are no extraneous arguments). Might not matter
+ * much, as switches from #! line seem to be acted upon (also), and
+ * so may be checked and trapped in perl. But, security checks must
+ * be done in suidperl and not deferred to perl. Note that suidperl
+ * does not get around to parsing (and checking) the switches on
+ * the #! line (but execs perl sooner).
+ * Allow (require) a trailing newline (which may be of two
+ * characters on some architectures?) (but no other trailing
+ * whitespace).
+ */
len = strlen(validarg);
if (strEQ(validarg," PHOOEY ") ||
- strnNE(s,validarg,len) || !isSPACE(s[len]))
+ strnNE(s,validarg,len) || !isSPACE(s[len]) ||
+ !(strlen(s) == len+1 || (strlen(s) == len+2 && isSPACE(s[len+1]))))
Perl_croak(aTHX_ "Args must match #! line");
#ifndef IAMSUID
- if (PL_euid != PL_uid && (PL_statbuf.st_mode & S_ISUID) &&
+ if (PL_fdscript < 0 &&
+ PL_euid != PL_uid && (PL_statbuf.st_mode & S_ISUID) &&
PL_euid == PL_statbuf.st_uid)
if (!PL_do_undump)
Perl_croak(aTHX_ "YOU HAVEN'T DISABLED SET-ID SCRIPTS IN THE KERNEL YET!\n\
FIX YOUR KERNEL, OR PUT A C WRAPPER AROUND THIS SCRIPT!\n");
#endif /* IAMSUID */
- if (PL_euid) { /* oops, we're not the setuid root perl */
- (void)PerlIO_close(PL_rsfp);
+ if (PL_fdscript < 0 &&
+ PL_euid) { /* oops, we're not the setuid root perl */
+ /* PSz 18 Feb 04
+ * When root runs a setuid script, we do not go through the same
+ * steps of execing sperl and then perl with fd scripts, but
+ * simply set up UIDs within the same perl invocation; so do
+ * not have the same checks (on options, whatever) that we have
+ * for plain users. No problem really: would have to be a script
+ * that does not actually work for plain users; and if root is
+ * foolish and can be persuaded to run such an unsafe script, he
+ * might run also non-setuid ones, and deserves what he gets.
+ *
+ * Or, we might drop the PL_euid check above (and rely just on
+ * PL_fdscript to avoid loops), and do the execs
+ * even for root.
+ */
#ifndef IAMSUID
- /* try again */
+ int which;
+ /* PSz 11 Nov 03
+ * Pass fd script to suidperl.
+ * Exec suidperl, substituting fd script for scriptname.
+ * Pass script name as "subdir" of fd, which perl will grok;
+ * in fact will use that to distinguish this from "normal"
+ * usage, see comments above.
+ */
+ PerlIO_rewind(PL_rsfp);
+ PerlLIO_lseek(PerlIO_fileno(PL_rsfp),(Off_t)0,0); /* just in case rewind didn't */
+ /* PSz 27 Feb 04 Sanity checks on scriptname */
+ if ((!scriptname) || (!*scriptname) ) {
+ Perl_croak(aTHX_ "No setuid script name\n");
+ }
+ if (*scriptname == '-') {
+ Perl_croak(aTHX_ "Setuid script name may not begin with dash\n");
+ /* Or we might confuse it with an option when replacing
+ * name in argument list, below (though we do pointer, not
+ * string, comparisons).
+ */
+ }
+ for (which = 1; PL_origargv[which] && PL_origargv[which] != scriptname; which++) ;
+ if (!PL_origargv[which]) {
+ Perl_croak(aTHX_ "Can't change argv to have fd script\n");
+ }
+ PL_origargv[which] = savepv(Perl_form(aTHX_ "/dev/fd/%d/%s",
+ PerlIO_fileno(PL_rsfp), PL_origargv[which]));
+#if defined(HAS_FCNTL) && defined(F_SETFD)
+ fcntl(PerlIO_fileno(PL_rsfp),F_SETFD,0); /* ensure no close-on-exec */
+#endif
PERL_FPU_PRE_EXEC
PerlProc_execv(Perl_form(aTHX_ "%s/sperl"PERL_FS_VER_FMT, BIN_EXP,
(int)PERL_REVISION, (int)PERL_VERSION,
(int)PERL_SUBVERSION), PL_origargv);
PERL_FPU_POST_EXEC
-#endif
- Perl_croak(aTHX_ "Can't do setuid\n");
+#endif /* IAMSUID */
+ Perl_croak(aTHX_ "Can't do setuid (cannot exec sperl)\n");
}
if (PL_statbuf.st_mode & S_ISGID && PL_statbuf.st_gid != PL_egid) {
+/* PSz 26 Feb 04
+ * This seems back to front: we try HAS_SETEGID first; if not available
+ * then try HAS_SETREGID; as a last chance we try HAS_SETRESGID. May be OK
+ * in the sense that we only want to set EGID; but are there any machines
+ * with either of the latter, but not the former? Same with UID, later.
+ */
#ifdef HAS_SETEGID
(void)setegid(PL_statbuf.st_gid);
#else
}
init_ids();
if (!cando(S_IXUSR,TRUE,&PL_statbuf))
- Perl_croak(aTHX_ "Permission denied\n"); /* they can't do this */
+ Perl_croak(aTHX_ "Effective UID cannot exec script\n"); /* they can't do this */
}
#ifdef IAMSUID
- else if (PL_preprocess)
+ else if (PL_preprocess) /* PSz 13 Nov 03 Caught elsewhere, useless(?!) here */
Perl_croak(aTHX_ "-P not allowed for setuid/setgid script\n");
- else if (fdscript >= 0)
- Perl_croak(aTHX_ "fd script not allowed in suidperl\n");
+ else if (PL_fdscript < 0 || PL_suidscript != 1)
+ /* PSz 13 Nov 03 Caught elsewhere, useless(?!) here */
+ Perl_croak(aTHX_ "(suid) fdscript needed in suidperl\n");
else {
- errno = EPERM;
- Perl_croak(aTHX_ "Permission denied\n");
+/* PSz 16 Sep 03 Keep neat error message */
+ Perl_croak(aTHX_ "Script is not setuid/setgid in suidperl\n");
}
/* We absolutely must clear out any saved ids here, so we */
/* exec the real perl, substituting fd script for scriptname. */
/* (We pass script name as "subdir" of fd, which perl will grok.) */
+ /*
+ * It might be thought that using setresgid and/or setresuid (changed to
+ * set the saved IDs) above might obviate the need to exec, and we could
+ * go on to "do the perl thing".
+ *
+ * Is there such a thing as "saved GID", and is that set for setuid (but
+ * not setgid) execution like suidperl? Without exec, it would not be
+ * cleared for setuid (but not setgid) scripts (or might need a dummy
+ * setresgid).
+ *
+ * We need suidperl to do the exact same argument checking that perl
+ * does. Thus it cannot be very small; while it could be significantly
+ * smaller, it is safer (simpler?) to make it essentially the same
+ * binary as perl (but they are not identical). - Maybe could defer that
+ * check to the invoked perl, and suidperl be a tiny wrapper instead;
+ * but prefer to do thorough checks in suidperl itself. Such deferral
+ * would make suidperl security rely on perl, a design no-no.
+ *
+ * Setuid things should be short and simple, thus easy to understand and
+ * verify. They should do their "own thing", without influence by
+ * attackers. It may help if their internal execution flow is fixed,
+ * regardless of platform: it may be best to exec anyway.
+ *
+ * Suidperl should at least be conceptually simple: a wrapper only,
+ * never to do any real perl. Maybe we should put
+ * #ifdef IAMSUID
+ * Perl_croak(aTHX_ "Suidperl should never do real perl\n");
+ * #endif
+ * into the perly bits.
+ */
PerlIO_rewind(PL_rsfp);
PerlLIO_lseek(PerlIO_fileno(PL_rsfp),(Off_t)0,0); /* just in case rewind didn't */
- for (which = 1; PL_origargv[which] && PL_origargv[which] != scriptname; which++) ;
- if (!PL_origargv[which]) {
- errno = EPERM;
- Perl_croak(aTHX_ "Permission denied\n");
- }
- PL_origargv[which] = savepv(Perl_form(aTHX_ "/dev/fd/%d/%s",
- PerlIO_fileno(PL_rsfp), PL_origargv[which]));
+ /* PSz 11 Nov 03
+ * Keep original arguments: suidperl already has fd script.
+ */
+/* for (which = 1; PL_origargv[which] && PL_origargv[which] != scriptname; which++) ; */
+/* if (!PL_origargv[which]) { */
+/* errno = EPERM; */
+/* Perl_croak(aTHX_ "Permission denied\n"); */
+/* } */
+/* PL_origargv[which] = savepv(Perl_form(aTHX_ "/dev/fd/%d/%s", */
+/* PerlIO_fileno(PL_rsfp), PL_origargv[which])); */
#if defined(HAS_FCNTL) && defined(F_SETFD)
fcntl(PerlIO_fileno(PL_rsfp),F_SETFD,0); /* ensure no close-on-exec */
#endif
(int)PERL_REVISION, (int)PERL_VERSION,
(int)PERL_SUBVERSION), PL_origargv);/* try again */
PERL_FPU_POST_EXEC
- Perl_croak(aTHX_ "Can't do setuid\n");
+ Perl_croak(aTHX_ "Can't do setuid (suidperl cannot exec perl)\n");
#endif /* IAMSUID */
#else /* !DOSUID */
if (PL_euid != PL_uid || PL_egid != PL_gid) { /* (suidperl doesn't exist, in fact) */
/* Should not happen: */
CHECK_MALLOC_TAINT(PL_uid && (PL_euid != PL_uid || PL_egid != PL_gid));
PL_tainting |= (PL_uid && (PL_euid != PL_uid || PL_egid != PL_gid));
+ /* BUG */
+ /* PSz 27 Feb 04
+ * Should go by suidscript, not uid!=euid: why disallow
+ * system("ls") in scripts run from setuid things?
+ * Or, is this run before we check arguments and set suidscript?
+ * What about SETUID_SCRIPTS_ARE_SECURE_NOW: could we use fdscript then?
+ * (We never have suidscript, can we be sure to have fdscript?)
+ * Or must then go by UID checks? See comments in forbid_setid also.
+ */
}
/* This is used very early in the lifetime of the program,
STATIC void
S_forbid_setid(pTHX_ char *s)
{
+#ifdef SETUID_SCRIPTS_ARE_SECURE_NOW
if (PL_euid != PL_uid)
Perl_croak(aTHX_ "No %s allowed while running setuid", s);
if (PL_egid != PL_gid)
Perl_croak(aTHX_ "No %s allowed while running setgid", s);
+#endif /* SETUID_SCRIPTS_ARE_SECURE_NOW */
+ /* PSz 29 Feb 04
+ * Checks for UID/GID above "wrong": why disallow
+ * perl -e 'print "Hello\n"'
+ * from within setuid things?? Simply drop them: replaced by
+ * fdscript/suidscript and #ifdef IAMSUID checks below.
+ *
+ * This may be too late for command-line switches. Will catch those on
+ * the #! line, after finding the script name and setting up
+ * fdscript/suidscript. Note that suidperl does not get around to
+ * parsing (and checking) the switches on the #! line, but checks that
+ * the two sets are identical.
+ *
+ * With SETUID_SCRIPTS_ARE_SECURE_NOW, could we use fdscript, also or
+ * instead, or would that be "too late"? (We never have suidscript, can
+ * we be sure to have fdscript?)
+ *
+ * Catch things with suidscript (in descendant of suidperl), even with
+ * right UID/GID. Was already checked in suidperl, with #ifdef IAMSUID,
+ * below; but I am paranoid.
+ *
+ * Also see comments about root running a setuid script, elsewhere.
+ */
+ if (PL_suidscript >= 0)
+ Perl_croak(aTHX_ "No %s allowed with (suid) fdscript", s);
+#ifdef IAMSUID
+ /* PSz 11 Nov 03 Catch it in suidperl, always! */
+ Perl_croak(aTHX_ "No %s allowed in suidperl", s);
+#endif /* IAMSUID */
}
void
https://perl5.git.perl.org / perl5.git / commitdiff