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[src/trunk]: src/usr.bin/patch From Martin Natano @bitrig: Use execve(2) inst...



details:   https://anonhg.NetBSD.org/src/rev/14d7d6b7b4ff
branches:  trunk
changeset: 809629:14d7d6b7b4ff
user:      christos <christos%NetBSD.org@localhost>
date:      Fri Jul 24 18:56:00 2015 +0000

description:
>From Martin Natano @bitrig: Use execve(2) instead of system to apply patches
that require rcs command execution instead system(3) to avoid malicious
filenames in patches causing bad things to happen. In the process, lose SCCS
support. It is not like we are shipping sccs commands for that to work.

diffstat:

 usr.bin/patch/inp.c |  109 +++++++++++++++++++++++++++++++--------------------
 1 files changed, 67 insertions(+), 42 deletions(-)

diffs (186 lines):

diff -r b1228ab1cbab -r 14d7d6b7b4ff usr.bin/patch/inp.c
--- a/usr.bin/patch/inp.c       Fri Jul 24 15:43:38 2015 +0000
+++ b/usr.bin/patch/inp.c       Fri Jul 24 18:56:00 2015 +0000
@@ -1,7 +1,7 @@
 /*
  * $OpenBSD: inp.c,v 1.34 2006/03/11 19:41:30 otto Exp $
  * $DragonFly: src/usr.bin/patch/inp.c,v 1.6 2007/09/29 23:11:10 swildner Exp $
- * $NetBSD: inp.c,v 1.23 2009/10/21 17:16:11 joerg Exp $
+ * $NetBSD: inp.c,v 1.24 2015/07/24 18:56:00 christos Exp $
  */
 
 /*
@@ -31,14 +31,16 @@
  */
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: inp.c,v 1.23 2009/10/21 17:16:11 joerg Exp $");
+__RCSID("$NetBSD: inp.c,v 1.24 2015/07/24 18:56:00 christos Exp $");
 
 #include <sys/types.h>
 #include <sys/file.h>
 #include <sys/stat.h>
 #include <sys/mman.h>
+#include <sys/wait.h>
 
 #include <ctype.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <libgen.h>
 #include <limits.h>
@@ -139,12 +141,14 @@
 static bool
 plan_a(const char *filename)
 {
-       int             ifd, statfailed;
+       int             ifd, statfailed, devnull, pstat;
        char            *p, *s, lbuf[MAXLINELEN];
        struct stat     filestat;
        off_t           i;
        ptrdiff_t       sz;
        size_t          iline, lines_allocated;
+       pid_t           pid;
+       char            *argp[4] = {NULL};
 
 #ifdef DEBUGGING
        if (debug & 8)
@@ -172,13 +176,13 @@
        }
        if (statfailed && check_only)
                fatal("%s not found, -C mode, can't probe further\n", filename);
-       /* For nonexistent or read-only files, look for RCS or SCCS versions.  */
+       /* For nonexistent or read-only files, look for RCS versions.  */
        if (statfailed ||
            /* No one can write to it.  */
            (filestat.st_mode & 0222) == 0 ||
            /* I can't write to it.  */
            ((filestat.st_mode & 0022) == 0 && filestat.st_uid != getuid())) {
-               const char      *cs = NULL, *filebase, *filedir;
+               char    *filebase, *filedir;
                struct stat     cstat;
                char *tmp_filename1, *tmp_filename2;
 
@@ -186,43 +190,26 @@
                tmp_filename2 = strdup(filename);
                if (tmp_filename1 == NULL || tmp_filename2 == NULL)
                        fatal("strdupping filename");
-               filebase = basename(tmp_filename1);
-               filedir = dirname(tmp_filename2);
-
-               /* Leave room in lbuf for the diff command.  */
-               s = lbuf + 20;
-
+ 
+               filebase = basename(tmp_filename1);
+               filedir = dirname(tmp_filename2);
+ 
 #define try(f, a1, a2, a3) \
-       (snprintf(s, sizeof lbuf - 20, f, a1, a2, a3), stat(s, &cstat) == 0)
-
-               if (try("%s/RCS/%s%s", filedir, filebase, RCSSUFFIX) ||
-                   try("%s/RCS/%s%s", filedir, filebase, "") ||
-                   try("%s/%s%s", filedir, filebase, RCSSUFFIX)) {
-                       snprintf(buf, buf_len, CHECKOUT, filename);
-                       snprintf(lbuf, sizeof lbuf, RCSDIFF, filename);
-                       cs = "RCS";
-               } else if (try("%s/SCCS/%s%s", filedir, SCCSPREFIX, filebase) ||
-                   try("%s/%s%s", filedir, SCCSPREFIX, filebase)) {
-                       snprintf(buf, buf_len, GET, s);
-                       snprintf(lbuf, sizeof lbuf, SCCSDIFF, s, filename);
-                       cs = "SCCS";
-               } else if (statfailed)
-                       fatal("can't find %s\n", filename);
-
-               free(tmp_filename1);
-               free(tmp_filename2);
+       (snprintf(lbuf, sizeof lbuf, f, a1, a2, a3), stat(lbuf, &cstat) == 0)
 
                /*
                 * else we can't write to it but it's not under a version
                 * control system, so just proceed.
                 */
-               if (cs) {
+               if (try("%s/RCS/%s%s", filedir, filebase, RCSSUFFIX) ||
+                   try("%s/RCS/%s%s", filedir, filebase, "") ||
+                   try("%s/%s%s", filedir, filebase, RCSSUFFIX)) {
                        if (!statfailed) {
                                if ((filestat.st_mode & 0222) != 0)
                                        /* The owner can write to it.  */
                                        fatal("file %s seems to be locked "
-                                           "by somebody else under %s\n",
-                                           filename, cs);
+                                           "by somebody else under RCS\n",
+                                           filename);
                                /*
                                 * It might be checked out unlocked.  See if
                                 * it's safe to check out the default version
@@ -230,21 +217,59 @@
                                 */
                                if (verbose)
                                        say("Comparing file %s to default "
-                                           "%s version...\n",
-                                           filename, cs);
-                               if (system(lbuf))
+                                           "RCS version...\n", filename);
+
+                               switch (pid = fork()) {
+                               case -1:
+                                       fatal("can't fork: %s\n",
+                                           strerror(errno));
+                               case 0:
+                                       devnull = open("/dev/null", O_RDONLY);
+                                       if (devnull == -1) {
+                                               fatal("can't open /dev/null: %s",
+                                                   strerror(errno));
+                                       }
+                                       (void)dup2(devnull, STDOUT_FILENO);
+                                       argp[0] = __UNCONST(RCSDIFF);
+                                       argp[1] = __UNCONST(filename);
+                                       execv(RCSDIFF, argp);
+                                       exit(127);
+                               }
+                               pid = waitpid(pid, &pstat, 0);
+                               if (pid == -1 || WEXITSTATUS(pstat) != 0) {
                                        fatal("can't check out file %s: "
-                                           "differs from default %s version\n",
-                                           filename, cs);
+                                           "differs from default RCS version\n",
+                                           filename);
+                               }
                        }
+
                        if (verbose)
-                               say("Checking out file %s from %s...\n",
-                                   filename, cs);
-                       if (system(buf) || stat(filename, &filestat))
-                               fatal("can't check out file %s from %s\n",
-                                   filename, cs);
+                               say("Checking out file %s from RCS...\n",
+                                   filename);
+
+                       switch (pid = fork()) {
+                       case -1:
+                               fatal("can't fork: %s\n", strerror(errno));
+                       case 0:
+                               argp[0] = __UNCONST(CHECKOUT);
+                               argp[1] = __UNCONST("-l");
+                               argp[2] = __UNCONST(filename);
+                               execv(CHECKOUT, argp);
+                               exit(127);
+                       }
+                       pid = waitpid(pid, &pstat, 0);
+                       if (pid == -1 || WEXITSTATUS(pstat) != 0 ||
+                           stat(filename, &filestat)) {
+                               fatal("can't check out file %s from RCS\n",
+                                   filename);
+                       }
+               } else if (statfailed) {
+                       fatal("can't find %s\n", filename);
                }
+               free(tmp_filename1);
+               free(tmp_filename2);
        }
+
        filemode = filestat.st_mode;
        if (!S_ISREG(filemode))
                fatal("%s is not a normal file--can't patch\n", filename);



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