Removed the broken code which claimed to lose the set[ug]id bits in

the !(pflag && setfile()) case for regular files unless the copy is
owned by the same user and group.  These bits have already been lost
(or never gained) in the correct way.  The code didn't actually lose
the bits; it depended on them being lost already (apparently in all
cases) and attempted to gain them as necessary, but it often gained
them (and sometimes collateral bits) when wrong:
- pflag && setfile() == 0 case (i.e., for a successful cp -p):
  setfile() copies all the attributes as correctly as possible (as
  specified by POSIX), and we sometimes messed up the up the mode by
  setting it again.  Also, if the file is immutable, then setting the
  mode again gave spurious errors (PR 20646).
- !pflag case.  If the target is created, POSIX requires it to not
  have the set[ug]id bits, but we sometimes copied them from the source.
  If the target already exists, POSIX requires its mode to be unchanged,
  but we sometimes copied the whole mode from the source.

PR:		20646
MFC after:	4 weeks

3 files changed, 4 insertions, 27 deletions

diff --git a/bin/cp/cp.c b/bin/cp/cp.c
index 0592444..3478c73 100644
--- a/bin/cp/cp.c
+++ b/bin/cp/cp.c
@@ -83,9 +83,7 @@ static const char rcsid[] =
 
 PATH_T to = { to.p_path, "", "" };
 
-uid_t myuid;
 int Rflag, iflag, pflag, rflag, fflag, vflag;
-int myumask;
 
 enum op { FILE_TO_FILE, FILE_TO_DIR, DIR_TO_DNE };
 
@@ -170,12 +168,6 @@ main(argc, argv)
 		fts_options |= FTS_LOGICAL;
 	}
 
-	myuid = getuid();
-
-	/* Copy the umask for explicit mode setting. */
-	myumask = umask(0);
-	(void)umask(myumask);
-
 	/* Save the target base in "to". */
 	target = argv[--argc];
 	if (strlcpy(to.p_path, target, sizeof(to.p_path)) >= sizeof(to.p_path))
diff --git a/bin/cp/extern.h b/bin/cp/extern.h
index 3b0ecef..4e5f07c 100644
--- a/bin/cp/extern.h
+++ b/bin/cp/extern.h
@@ -41,8 +41,7 @@ typedef struct {
 } PATH_T;
 
 extern PATH_T to;
-extern uid_t myuid;
-extern int iflag, pflag, fflag, vflag, myumask;
+extern int iflag, pflag, fflag, vflag;
 
 #include <sys/cdefs.h>
 
diff --git a/bin/cp/utils.c b/bin/cp/utils.c
index 110cc79..479550e 100644
--- a/bin/cp/utils.c
+++ b/bin/cp/utils.c
@@ -63,7 +63,7 @@ copy_file(entp, dne)
 	int dne;
 {
 	static char buf[MAXBSIZE];
-	struct stat to_stat, *fs;
+	struct stat *fs;
 	int ch, checkch, from_fd, rcount, rval, to_fd, wcount, wresid;
 	char *bufp;
 #ifdef VM_AND_BUFFER_CACHE_SYNCHRONIZED
@@ -180,22 +180,6 @@ copy_file(entp, dne)
 
 	if (pflag && setfile(fs, to_fd))
 		rval = 1;
-	/*
-	 * If the source was setuid or setgid, lose the bits unless the
-	 * copy is owned by the same user and group.
-	 */
-#define	RETAINBITS \
-	(S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO)
-	else if (fs->st_mode & (S_ISUID | S_ISGID) && fs->st_uid == myuid) {
-		if (fstat(to_fd, &to_stat)) {
-			warn("%s", to.p_path);
-			rval = 1;
-		} else if (fs->st_gid == to_stat.st_gid &&
-		    fchmod(to_fd, fs->st_mode & RETAINBITS & ~myumask)) {
-			warn("%s", to.p_path);
-			rval = 1;
-		}
-	}
 	(void)close(from_fd);
 	if (close(to_fd)) {
 		warn("%s", to.p_path);
@@ -260,6 +244,8 @@ copy_special(from_stat, exists)
 	return (pflag ? setfile(from_stat, 0) : 0);
 }
 
+#define	RETAINBITS \
+	(S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO)
 
 int
 setfile(fs, fd)