[hackers] [sbase] tar: improve file status handling on extract || Brad Barden

From: <git_AT_suckless.org>
Date: Fri, 20 Nov 2015 10:58:43 +0100 (CET)

commit 211c565b3d560ad16ef20359d6efe37d0783c583
Author: Brad Barden <brad_AT_13os.net>
AuthorDate: Wed Nov 18 20:50:50 2015 -0600
Commit: sin <sin_AT_2f30.org>
CommitDate: Fri Nov 20 09:58:38 2015 +0000

    tar: improve file status handling on extract
    
    by re-ordering when chmod/chown is done, only a list of directories (not
    all files) need be kept for fixing mtime.
    
    this also fixes an issue where set-user-id files in a tar may not work. chmod
    is done before chown and before the file is written. if ownership changes, or
    the file is being written as a normal user, the setuid bit would be cleared.
    
    also fixes ownership of symbolic links. previously a chown() was called,
    which would change the ownership of the link target. lchown() is now
    used for symbolic links.
    
    renamed all ent, ent* functions to dir* as it better describes what they
    do.
    
    use timespec/utimensat instead of timeval/utimes to get AT_SYMLINK_NOFOLLOW

diff --git a/tar.c b/tar.c
index de58247..e8dd26a 100644
--- a/tar.c
+++ b/tar.c
_AT_@ -48,12 +48,12 @@ struct header {
         char prefix[155];
 };
 
-static struct ent {
+static struct dirtime {
         char *name;
         time_t mtime;
-} *ents;
+} *dirtimes;
 
-static size_t entslen;
+static size_t dirtimeslen;
 
 static int tarfd;
 static ino_t tarinode;
_AT_@ -72,20 +72,20 @@ static const char *filtertools[] = {
 };
 
 static void
-pushent(char *name, time_t mtime)
+pushdirtime(char *name, time_t mtime)
 {
- ents = reallocarray(ents, entslen + 1, sizeof(*ents));
- ents[entslen].name = strdup(name);
- ents[entslen].mtime = mtime;
- entslen++;
+ dirtimes = reallocarray(dirtimes, dirtimeslen + 1, sizeof(*dirtimes));
+ dirtimes[dirtimeslen].name = strdup(name);
+ dirtimes[dirtimeslen].mtime = mtime;
+ dirtimeslen++;
 }
 
-static struct ent *
-popent(void)
+static struct dirtime *
+popdirtime(void)
 {
- if (entslen) {
- entslen--;
- return &ents[entslen];
+ if (dirtimeslen) {
+ dirtimeslen--;
+ return &dirtimes[dirtimeslen];
         }
         return NULL;
 }
_AT_@ -254,6 +254,7 @@ unarchive(char *fname, ssize_t l, char b[BLKSIZ])
         long mode, major, minor, type, mtime, uid, gid;
         struct header *h = (struct header *)b;
         int fd = -1;
+ struct timespec times[2];
 
         if (!mflag && ((mtime = strtol(h->mtime, &p, 8)) < 0 || *p != '\0'))
                 eprintf("strtol %s: invalid number\n", h->mtime);
_AT_@ -273,8 +274,6 @@ unarchive(char *fname, ssize_t l, char b[BLKSIZ])
                 fd = open(fname, O_WRONLY | O_TRUNC | O_CREAT, 0600);
                 if (fd < 0)
                         eprintf("open %s:", fname);
- if (fchmod(fd, mode) < 0)
- eprintf("fchmod %s:", fname);
                 break;
         case HARDLINK:
         case SYMLINK:
_AT_@ -290,6 +289,7 @@ unarchive(char *fname, ssize_t l, char b[BLKSIZ])
                         eprintf("strtol %s: invalid number\n", h->mode);
                 if (mkdir(fname, (mode_t)mode) < 0 && errno != EEXIST)
                         eprintf("mkdir %s:", fname);
+ pushdirtime(fname, mtime);
                 break;
         case CHARDEV:
         case BLOCKDEV:
_AT_@ -317,8 +317,6 @@ unarchive(char *fname, ssize_t l, char b[BLKSIZ])
                 eprintf("strtol %s: invalid number\n", h->uid);
         if ((gid = strtol(h->gid, &p, 8)) < 0 || *p != '\0')
                 eprintf("strtol %s: invalid number\n", h->gid);
- if (!getuid() && chown(fname, uid, gid))
- weprintf("chown %s:", fname);
 
         if (fd != -1) {
                 for (; l > 0; l -= BLKSIZ)
_AT_@ -327,7 +325,20 @@ unarchive(char *fname, ssize_t l, char b[BLKSIZ])
                 close(fd);
         }
 
- pushent(fname, mtime);
+ times[0].tv_sec = times[1].tv_sec = mtime;
+ times[0].tv_nsec = times[1].tv_nsec = 0;
+ if (!mflag && utimensat(AT_FDCWD, fname, times, AT_SYMLINK_NOFOLLOW) < 0)
+ weprintf("utimensat %s:\n", fname);
+ if (h->type == SYMLINK) {
+ if (!getuid() && lchown(fname, uid, gid))
+ weprintf("lchown %s:\n", fname);
+ } else {
+ if (!getuid() && chown(fname, uid, gid))
+ weprintf("chown %s:\n", fname);
+ if (chmod(fname, mode) < 0)
+ eprintf("fchmod %s:\n", fname);
+ }
+
         return 0;
 }
 
_AT_@ -420,9 +431,9 @@ static void
 xt(int argc, char *argv[], int mode)
 {
         char b[BLKSIZ], fname[256 + 1], *p;
- struct timeval times[2];
+ struct timespec times[2];
         struct header *h = (struct header *)b;
- struct ent *ent;
+ struct dirtime *dirtime;
         long size;
         int i, n;
         int (*fn)(char *, ssize_t, char[BLKSIZ]) = (mode == 'x') ? unarchive : print;
_AT_@ -463,16 +474,16 @@ xt(int argc, char *argv[], int mode)
                         puts(fname);
         }
 
- if (!mflag) {
- while ((ent = popent())) {
- times[0].tv_sec = times[1].tv_sec = ent->mtime;
- times[0].tv_usec = times[1].tv_usec = 0;
- if (utimes(ent->name, times) < 0)
- weprintf("utimes %s:", ent->name);
- free(ent->name);
+ if (mode == 'x' && !mflag) {
+ while ((dirtime = popdirtime())) {
+ times[0].tv_sec = times[1].tv_sec = dirtime->mtime;
+ times[0].tv_nsec = times[1].tv_nsec = 0;
+ if (utimensat(AT_FDCWD, dirtime->name, times, 0) < 0)
+ eprintf("utimensat %s:", fname);
+ free(dirtime->name);
                 }
- free(ents);
- ents = NULL;
+ free(dirtimes);
+ dirtimes = NULL;
         }
 }
 
Received on Fri Nov 20 2015 - 10:58:43 CET