Changeset 1765 in MondoRescue for branches/2.2.5/mindi-busybox/libbb/copy_file.c

Timestamp:

Nov 4, 2007, 3:16:40 AM (17 years ago)

Author:

Bruno Cornec

Message:

Update to busybox 1.7.2

File:

• branches/2.2.5/mindi-busybox/libbb/copy_file.c (modified) (5 diffs)

branches/2.2.5/mindi-busybox/libbb/copy_file.c

@@ -4 +4 @@
  *
  * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
+ * SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp>
  *
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
@@ -10 +11 @@
 
 #include "libbb.h"
-#include <utime.h>
-#include <errno.h>
-
+
+// POSIX: if exists and -i, ask (w/o -i assume yes).
+// Then open w/o EXCL (yes, not unlink!).
+// If open still fails and -f, try unlink, then try open again.
+// Result: a mess:
+// If dest is a softlink, we overwrite softlink's destination!
+// (or fail, if it points to dir/nonexistent location/etc).
+// This is strange, but POSIX-correct.
+// coreutils cp has --remove-destination to override this...
+//
+// NB: we have special code which still allows for "cp file /dev/node"
+// to work POSIX-ly (the only realistic case where it makes sense)
+
+#define DO_POSIX_CP 0  /* 1 - POSIX behavior, 0 - safe behavior */
+
+// errno must be set to relevant value ("why we cannot create dest?")
+// for POSIX mode to give reasonable error message
+static int ask_and_unlink(const char *dest, int flags)
+{
+#if DO_POSIX_CP
+    if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) {
+        // Either it exists, or the *path* doesnt exist
+        bb_perror_msg("cannot create '%s'", dest);
+        return -1;
+    }
+#endif
+    // If !DO_POSIX_CP, act as if -f is always in effect - we don't want
+    // "cannot create" msg, we want unlink to be done (silently unless -i).
+
+    // TODO: maybe we should do it only if ctty is present?
+    if (flags & FILEUTILS_INTERACTIVE) {
+        // We would not do POSIX insanity. -i asks,
+        // then _unlinks_ the offender. Presto.
+        // (No "opening without O_EXCL", no "unlink only if -f")
+        // Or else we will end up having 3 open()s!
+        fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
+        if (!bb_ask_confirmation())
+            return 0; // not allowed to overwrite
+    }
+    if (unlink(dest) < 0) {
+        bb_perror_msg("cannot remove '%s'", dest);
+        return -1; // error
+    }
+    return 1; // ok (to try again)
+}
+
+/* Return:
+ * -1 error, copy not made
+ *  0 copy is made or user answered "no" in interactive mode
+ *    (failures to preserve mode/owner/times are not reported in exit code)
+ */
 int copy_file(const char *source, const char *dest, int flags)
 {
+    /* This is a recursive function, try to minimize stack usage */
+    /* NB: each struct stat is ~100 bytes */
     struct stat source_stat;
     struct stat dest_stat;
-    int dest_exists = 0;
-    int status = 0;
-
-    if ((!(flags & FILEUTILS_DEREFERENCE) &&
-            lstat(source, &source_stat) < 0) ||
-            ((flags & FILEUTILS_DEREFERENCE) &&
-             stat(source, &source_stat) < 0)) {
-        bb_perror_msg("%s", source);
+    signed char retval = 0;
+    signed char dest_exists = 0;
+    signed char ovr;
+
+#define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE)
+
+    if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
+        // This may be a dangling symlink.
+        // Making [sym]links to dangling symlinks works, so...
+        if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK))
+            goto make_links;
+        bb_perror_msg("cannot stat '%s'", source);
         return -1;
     }
@@ -30 +85 @@
     if (lstat(dest, &dest_stat) < 0) {
         if (errno != ENOENT) {
-            bb_perror_msg("unable to stat `%s'", dest);
+            bb_perror_msg("cannot stat '%s'", dest);
             return -1;
         }
     } else {
-        if (source_stat.st_dev == dest_stat.st_dev &&
-            source_stat.st_ino == dest_stat.st_ino)
-        {
-            bb_error_msg("`%s' and `%s' are the same file", source, dest);
+        if (source_stat.st_dev == dest_stat.st_dev
+         && source_stat.st_ino == dest_stat.st_ino
+        ) {
+            bb_error_msg("'%s' and '%s' are the same file", source, dest);
             return -1;
         }
         dest_exists = 1;
     }
+
+#if ENABLE_SELINUX
+    if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
+        security_context_t con;
+        if (lgetfilecon(source, &con) >= 0) {
+            if (setfscreatecon(con) < 0) {
+                bb_perror_msg("cannot set setfscreatecon %s", con);
+                freecon(con);
+                return -1;
+            }
+        } else if (errno == ENOTSUP || errno == ENODATA) {
+            setfscreatecon_or_die(NULL);
+        } else {
+            bb_perror_msg("cannot lgetfilecon %s", source);
+            return -1;
+        }
+    }
+#endif
 
     if (S_ISDIR(source_stat.st_mode)) {
         DIR *dp;
+        const char *tp;
         struct dirent *d;
         mode_t saved_umask = 0;
 
         if (!(flags & FILEUTILS_RECUR)) {
-            bb_error_msg("%s: omitting directory", source);
-            return -1;
-        }
-
-        /* Create DEST.  */
+            bb_error_msg("omitting directory '%s'", source);
+            return -1;
+        }
+
+        /* Did we ever create source ourself before? */
+        tp = is_in_ino_dev_hashtable(&source_stat);
+        if (tp) {
+            /* We did! it's a recursion! man the lifeboats... */
+            bb_error_msg("recursion detected, omitting directory '%s'",
+                    source);
+            return -1;
+        }
+
+        /* Create DEST */
         if (dest_exists) {
             if (!S_ISDIR(dest_stat.st_mode)) {
-                bb_error_msg("`%s' is not a directory", dest);
-                return -1;
-            }
+                bb_error_msg("target '%s' is not a directory", dest);
+                return -1;
+            }
+            /* race here: user can substitute a symlink between
+             * this check and actual creation of files inside dest */
         } else {
             mode_t mode;
@@ -66 +151 @@
             if (!(flags & FILEUTILS_PRESERVE_STATUS))
                 mode = source_stat.st_mode & ~saved_umask;
+            /* Allow owner to access new dir (at least for now) */
             mode |= S_IRWXU;
-
             if (mkdir(dest, mode) < 0) {
                 umask(saved_umask);
-                bb_perror_msg("cannot create directory `%s'", dest);
-                return -1;
-            }
-
+                bb_perror_msg("cannot create directory '%s'", dest);
+                return -1;
+            }
             umask(saved_umask);
-        }
-
-        /* Recursively copy files in SOURCE.  */
-        if ((dp = bb_opendir(source)) == NULL) {
-            status = -1;
-            goto preserve_status;
+            /* need stat info for add_to_ino_dev_hashtable */
+            if (lstat(dest, &dest_stat) < 0) {
+                bb_perror_msg("cannot stat '%s'", dest);
+                return -1;
+            }
+        }
+        /* remember (dev,inode) of each created dir.
+         * NULL: name is not remembered */
+        add_to_ino_dev_hashtable(&dest_stat, NULL);
+
+        /* Recursively copy files in SOURCE */
+        dp = opendir(source);
+        if (dp == NULL) {
+            retval = -1;
+            goto preserve_mode_ugid_time;
         }
 
@@ -87 +180 @@
 
             new_source = concat_subpath_file(source, d->d_name);
-            if(new_source == NULL)
+            if (new_source == NULL)
                 continue;
             new_dest = concat_path_file(dest, d->d_name);
             if (copy_file(new_source, new_dest, flags) < 0)
-                status = -1;
+                retval = -1;
             free(new_source);
             free(new_dest);
         }
-        /* closedir have only EBADF error, but "dp" not changes */
         closedir(dp);
 
-        if (!dest_exists &&
-                chmod(dest, source_stat.st_mode & ~saved_umask) < 0) {
-            bb_perror_msg("unable to change permissions of `%s'", dest);
-            status = -1;
-        }
-    } else if (S_ISREG(source_stat.st_mode) ||
-           (S_ISLNK(source_stat.st_mode) && (flags & FILEUTILS_DEREFERENCE)))
-    {
+        if (!dest_exists
+         && chmod(dest, source_stat.st_mode & ~saved_umask) < 0
+        ) {
+            bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
+            /* retval = -1; - WRONG! copy *WAS* made */
+        }
+        goto preserve_mode_ugid_time;
+    }
+
+    if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
+        int (*lf)(const char *oldpath, const char *newpath);
+ make_links:
+        // Hmm... maybe
+        // if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
+        // (but realpath returns NULL on dangling symlinks...)
+        lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
+        if (lf(source, dest) < 0) {
+            ovr = ask_and_unlink(dest, flags);
+            if (ovr <= 0)
+                return ovr;
+            if (lf(source, dest) < 0) {
+                bb_perror_msg("cannot create link '%s'", dest);
+                return -1;
+            }
+        }
+        /* _Not_ jumping to preserve_mode_ugid_time:
+         * hard/softlinks don't have those */
+        return 0;
+    }
+
+    if (S_ISREG(source_stat.st_mode)
+     /* DEREF uses stat, which never returns S_ISLNK() == true. */
+     /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
+    ) {
         int src_fd;
         int dst_fd;
-        if (ENABLE_FEATURE_PRESERVE_HARDLINKS) {
-            char *link_name;
-
-            if (!(flags & FILEUTILS_DEREFERENCE) &&
-                    is_in_ino_dev_hashtable(&source_stat, &link_name)) {
-                if (link(link_name, dest) < 0) {
-                    bb_perror_msg("unable to link `%s'", dest);
+
+        if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
+            const char *link_target;
+            link_target = is_in_ino_dev_hashtable(&source_stat);
+            if (link_target) {
+                if (link(link_target, dest) < 0) {
+                    ovr = ask_and_unlink(dest, flags);
+                    if (ovr <= 0)
+                        return ovr;
+                    if (link(link_target, dest) < 0) {
+                        bb_perror_msg("cannot create link '%s'", dest);
+                        return -1;
+                    }
+                }
+                return 0;
+            }
+            add_to_ino_dev_hashtable(&source_stat, dest);
+        }
+
+        src_fd = open_or_warn(source, O_RDONLY);
+        if (src_fd < 0)
+            return -1;
+
+        /* POSIX way is a security problem versus symlink attacks,
+         * we do it only for non-symlinks, and only for non-recursive,
+         * non-interactive cp. NB: it is still racy
+         * for "cp file /home/bad_user/file" case
+         * (user can rm file and create a link to /etc/passwd) */
+        if (DO_POSIX_CP
+         || (dest_exists && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE))
+             && !S_ISLNK(dest_stat.st_mode))
+        ) {
+            dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
+        } else  /* safe way: */
+            dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode);
+        if (dst_fd == -1) {
+            ovr = ask_and_unlink(dest, flags);
+            if (ovr <= 0) {
+                close(src_fd);
+                return ovr;
+            }
+            /* It shouldn't exist. If it exists, do not open (symlink attack?) */
+            dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode);
+            if (dst_fd < 0) {
+                close(src_fd);
+                return -1;
+            }
+        }
+
+#if ENABLE_SELINUX
+        if (((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT)
+            || (flags & FILEUTILS_SET_SECURITY_CONTEXT))
+         && is_selinux_enabled() > 0
+        ) {
+            security_context_t con;
+            if (getfscreatecon(&con) == -1) {
+                bb_perror_msg("getfscreatecon");
+                return -1;
+            }
+            if (con) {
+                if (setfilecon(dest, con) == -1) {
+                    bb_perror_msg("setfilecon:%s,%s", dest, con);
+                    freecon(con);
                     return -1;
                 }
-
-                return 0;
-            }
-            add_to_ino_dev_hashtable(&source_stat, dest);
-        }
-        src_fd = open(source, O_RDONLY);
-        if (src_fd == -1) {
-            bb_perror_msg("unable to open `%s'", source);
-            return(-1);
-        }
-
-        if (dest_exists) {
-            if (flags & FILEUTILS_INTERACTIVE) {
-                fprintf(stderr, "%s: overwrite `%s'? ", bb_applet_name, dest);
-                if (!bb_ask_confirmation()) {
-                    close (src_fd);
-                    return 0;
-                }
-            }
-
-            dst_fd = open(dest, O_WRONLY|O_TRUNC);
-            if (dst_fd == -1) {
-                if (!(flags & FILEUTILS_FORCE)) {
-                    bb_perror_msg("unable to open `%s'", dest);
-                    close(src_fd);
-                    return -1;
-                }
-
-                if (unlink(dest) < 0) {
-                    bb_perror_msg("unable to remove `%s'", dest);
-                    close(src_fd);
-                    return -1;
-                }
-
-                goto dest_removed;
-            }
-        } else {
-dest_removed:
-            dst_fd = open(dest, O_WRONLY|O_CREAT, source_stat.st_mode);
-            if (dst_fd == -1) {
-                bb_perror_msg("unable to open `%s'", dest);
-                close(src_fd);
-                return(-1);
-            }
-        }
-
+                freecon(con);
+            }
+        }
+#endif
         if (bb_copyfd_eof(src_fd, dst_fd) == -1)
-            status = -1;
-
+            retval = -1;
+        /* Ok, writing side I can understand... */
         if (close(dst_fd) < 0) {
-            bb_perror_msg("unable to close `%s'", dest);
-            status = -1;
-        }
-
-        if (close(src_fd) < 0) {
-            bb_perror_msg("unable to close `%s'", source);
-            status = -1;
-        }
-    } else if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode) ||
-        S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode) ||
-        S_ISLNK(source_stat.st_mode)) {
-
-        if (dest_exists) {
-            if((flags & FILEUTILS_FORCE) == 0) {
-                fprintf(stderr, "`%s' exists\n", dest);
-                return -1;
-            }
-            if(unlink(dest) < 0) {
-                bb_perror_msg("unable to remove `%s'", dest);
-                return -1;
-            }
-        }
-        if (S_ISFIFO(source_stat.st_mode)) {
-            if (mkfifo(dest, source_stat.st_mode) < 0) {
-                bb_perror_msg("cannot create fifo `%s'", dest);
-                return -1;
-            }
-        } else if (S_ISLNK(source_stat.st_mode)) {
-            char *lpath;
-
-            lpath = xreadlink(source);
-            if (symlink(lpath, dest) < 0) {
-                bb_perror_msg("cannot create symlink `%s'", dest);
-                return -1;
-            }
+            bb_perror_msg("cannot close '%s'", dest);
+            retval = -1;
+        }
+        /* ...but read size is already checked by bb_copyfd_eof */
+        close(src_fd);
+        goto preserve_mode_ugid_time;
+    }
+
+    /* Source is a symlink or a special file */
+    /* We are lazy here, a bit lax with races... */
+    if (dest_exists) {
+        errno = EEXIST;
+        ovr = ask_and_unlink(dest, flags);
+        if (ovr <= 0)
+            return ovr;
+    }
+    if (S_ISLNK(source_stat.st_mode)) {
+        char *lpath = xmalloc_readlink_or_warn(source);
+        if (lpath) {
+            int r = symlink(lpath, dest);
             free(lpath);
-
+            if (r < 0) {
+                bb_perror_msg("cannot create symlink '%s'", dest);
+                return -1;
+            }
             if (flags & FILEUTILS_PRESERVE_STATUS)
                 if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
-                    bb_perror_msg("unable to preserve ownership of `%s'", dest);
-
-            return 0;
-
-        } else {
-            if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
-                bb_perror_msg("unable to create `%s'", dest);
-                return -1;
-            }
+                    bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
+        }
+        /* _Not_ jumping to preserve_mode_ugid_time:
+         * symlinks don't have those */
+        return 0;
+    }
+    if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
+     || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
+    ) {
+        if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
+            bb_perror_msg("cannot create '%s'", dest);
+            return -1;
         }
     } else {
-        bb_error_msg("internal error: unrecognized file type");
+        bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
         return -1;
     }
 
-preserve_status:
-
-    if (flags & FILEUTILS_PRESERVE_STATUS) {
+ preserve_mode_ugid_time:
+
+    if (flags & FILEUTILS_PRESERVE_STATUS
+    /* Cannot happen: */
+    /* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
+    ) {
         struct utimbuf times;
-        char *msg="unable to preserve %s of `%s'";
 
         times.actime = source_stat.st_atime;
         times.modtime = source_stat.st_mtime;
+        /* BTW, utimes sets usec-precision time - just FYI */
         if (utime(dest, &times) < 0)
-            bb_perror_msg(msg, "times", dest);
+            bb_perror_msg("cannot preserve %s of '%s'", "times", dest);
         if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
             source_stat.st_mode &= ~(S_ISUID | S_ISGID);
-            bb_perror_msg(msg, "ownership", dest);
+            bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
         }
         if (chmod(dest, source_stat.st_mode) < 0)
-            bb_perror_msg(msg, "permissions", dest);
-    }
-
-    return status;
+            bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
+    }
+
+    return retval;
 }