src/client/scanner.c

@@ -98,17 +98,51 @@ static DirEntry* dir_entry_create(const char* path, int depth, FilterNode* conte
   return de;
 }
 
-static bool safe_relative_link(const char* source_root, const char* containing_dir,
-                               const char* link_target) {
-  char root[PATH_MAX];
-  if (!realpath(source_root, root))
-    return false;
-  char* joined = path_cat(containing_dir, link_target);
-  char resolved[PATH_MAX];
-  bool safe = joined && realpath(joined, resolved) && strncmp(root, resolved, strlen(root)) == 0 &&
-              (resolved[strlen(root)] == '\0' || resolved[strlen(root)] == '/');
-  free(joined);
-  return safe;
+/* How rsync's readlink_stat()/generator resolves one source symlink. */
+typedef enum {
+  LINK_ACTION_SKIP,           /* not transferred (no link option) */
+  LINK_ACTION_SKIP_PROTECTED, /* ignored as unsafe by --safe-links; rsync keeps
+                                 it in the transfer, so its destination mirror
+                                 must be protected from --delete */
+  LINK_ACTION_DEREF,          /* follow the referent (--copy-links, an unsafe
+                                 target under --copy-unsafe-links, or -k dir) */
+  LINK_ACTION_CARRY,          /* transmit the link itself (-l) */
+} LinkAction;
+
+/* Apply rsync's symlink-resolution precedence to one S_ISLNK entry:
+ *   --copy-links  dereferences every symlink;
+ *   --copy-unsafe-links  dereferences only targets unsafe_symlink() flags;
+ *   -k/--copy-dirlinks  dereferences only a symlink whose referent is a dir;
+ *   --safe-links  (receiver-side in rsync; modelled here) ignores an unsafe
+ *                 target that would otherwise be carried; with --munge-links
+ *                 every stored target becomes absolute, so --safe-links then
+ *                 ignores every symlink, exactly as rsync documents;
+ *   -l/--links  carries the link.
+ * `link_rel` is the symlink's transfer-relative path (incl. name) and is used
+ * only for the lexical unsafe test.  `target` receives the raw link value. */
+static LinkAction scanner_link_action(const ScannerOptions* options, const char* path,
+                                      const char* link_rel, char* target, size_t target_size) {
+  if (!options->follow_symlinks && !options->copy_links && !options->safe_links &&
+      !options->copy_unsafe_links && !options->copy_dirlinks)
+    return LINK_ACTION_SKIP;
+  ssize_t length = readlink(path, target, target_size - 1);
+  if (length < 0)
+    return LINK_ACTION_SKIP;
+  target[length] = '\0';
+
+  bool unsafe = file_symlink_unsafe(target, link_rel);
+  if (options->copy_links || (options->copy_unsafe_links && unsafe))
+    return LINK_ACTION_DEREF;
+  if (options->copy_dirlinks) {
+    struct stat ref;
+    if (stat(path, &ref) == 0 && S_ISDIR(ref.st_mode))
+      return LINK_ACTION_DEREF;
+  }
+  if (options->safe_links && (unsafe || options->munge_links))
+    return LINK_ACTION_SKIP_PROTECTED;
+  if (!options->follow_symlinks || target[0] == '\0')
+    return LINK_ACTION_SKIP;
+  return LINK_ACTION_CARRY;
 }
 
 typedef struct {
@@ -210,24 +244,35 @@ static void scanner_assign_hardlink(DirectoryScanner* scanner, HardLinkTable* ta
   }
 }
 
-/* Phase 4 special/devices: detect a device (char/block), FIFO or socket entry
-   and, when the matching --devices/--specials flag asks it be preserved,
-   convert the File into a node to recreate (is_special, empty payload) with its
-   device rdev captured from the source stat.  When the entry is not preserved
-   (or --copy-devices instead copies its content as an ordinary regular file)
-   the File is left as a normal data file.  Returns true when converted. */
-static bool scanner_prepare_special(bool preserve_devices, bool preserve_specials, File* file,
+/* Phase 4 special/devices decision for one non-regular entry, matching rsync:
+   - a char/block device is RECREATED as a node under -D/--devices, unless
+     --copy-devices asks for its content to be copied into a regular file;
+   - a FIFO/socket is RECREATED under --specials;
+   - when the matching flag is absent the entry is SKIPPED ("skipping
+     non-regular file"), exactly like rsync's default, instead of being
+     silently copied as a zero-length regular file;
+   - anything else (regular/directory) is left to the normal data path. */
+typedef enum {
+  SCANNER_SPECIAL_REGULAR,  /* ordinary file: transfer content */
+  SCANNER_SPECIAL_RECREATE, /* is_special node to recreate on the receiver */
+  SCANNER_SPECIAL_SKIP,     /* non-regular entry not requested: skip */
+} ScannerSpecial;
+
+static ScannerSpecial scanner_prepare_special(bool preserve_devices, bool preserve_specials,
+                                              bool copy_devices, File* file,
                                               const struct stat* stats) {
   if (!file || !stats)
-    return false;
+    return SCANNER_SPECIAL_REGULAR;
   bool is_device = S_ISCHR(stats->st_mode) || S_ISBLK(stats->st_mode);
   bool is_fifo = S_ISFIFO(stats->st_mode);
   bool is_socket = S_ISSOCK(stats->st_mode);
   if (!is_device && !is_fifo && !is_socket)
-    return false;
+    return SCANNER_SPECIAL_REGULAR;
+  if (is_device && copy_devices)
+    return SCANNER_SPECIAL_REGULAR; /* copy device content as a regular file */
   bool preserve = is_device ? preserve_devices : preserve_specials;
   if (!preserve)
-    return false;
+    return SCANNER_SPECIAL_SKIP;
   file->is_special = true;
   file->data->size = 0;
   file->data->data = NULL;
@@ -235,7 +280,7 @@ static bool scanner_prepare_special(bool preserve_devices, bool preserve_special
     file->rdev_major = (int32_t)major(stats->st_rdev);
     file->rdev_minor = (int32_t)minor(stats->st_rdev);
   }
-  return true;
+  return SCANNER_SPECIAL_RECREATE;
 }
 
 /* Append `rel` to the caller's exclusion sink, taking `mtx` when shared across
@@ -306,10 +351,11 @@ static int open_directory_filter_context(DirectoryScanner* scanner, const Filter
   return 0;
 }
 
-/* Inspect symlinks, resolve the entry type, and apply file filters once for both scanners. */
-static int scanner_inspect_entry(const ScannerOptions* options, const char* source_root,
-                                 const char* containing_dir, const char* name,
-                                 ScannerEntry* entry) {
+/* Inspect symlinks, resolve the entry type, and apply file filters once for both scanners.
+ * `link_rel` is the entry's path relative to the transfer root (including its
+ * name), used for the lexical rsync unsafe-symlink test. */
+static int scanner_inspect_entry(const ScannerOptions* options, const char* containing_dir,
+                                 const char* link_rel, const char* name, ScannerEntry* entry) {
   entry->excluded = false;
   entry->is_symlink = false;
   entry->link_target = NULL;
@@ -322,72 +368,49 @@ static int scanner_inspect_entry(const ScannerOptions* options, const char* sour
     free(entry->path);
     return 0;
   }
-  bool is_symlink = S_ISLNK(link_stats.st_mode);
-  if (!is_symlink)
+  if (!S_ISLNK(link_stats.st_mode))
     goto regular;
 
-  /* Symlink: choose between dereferencing (---copy-links / --safe-links /
-     --copy-unsafe-links, plus -k for symlinks-to-directories) and carrying the
-     link through as a symlink (-l, and -k for symlinks-to-files).  No link
-     option means the symlink is skipped entirely (pre-existing behavior). */
-  const bool any_link_option = options->follow_symlinks || options->copy_links ||
-                               options->safe_links || options->copy_unsafe_links ||
-                               options->copy_dirlinks;
-  if (!any_link_option)
-    goto skip;
-
   char link_target[4096];
-  ssize_t length = readlink(entry->path, link_target, sizeof(link_target) - 1);
-  if (length < 0)
+  switch (scanner_link_action(options, entry->path, link_rel, link_target, sizeof(link_target))) {
+  case LINK_ACTION_SKIP:
     goto skip;
-  link_target[length] = '\0';
-
-  if (options->safe_links) {
-    if (link_target[0] == '/' || !safe_relative_link(source_root, containing_dir, link_target))
+  case LINK_ACTION_SKIP_PROTECTED:
+    /* --safe-links ignored the link, but rsync still counts it as present in
+       the transfer, so its destination mirror survives --delete.  Record it as
+       an excluded path (the same delete-protection channel as a filter prune). */
+    entry->excluded = true;
+    goto skip;
+  case LINK_ACTION_DEREF:
+    if (stat(entry->path, &entry->stats) != 0) {
+      /* rsync reports "symlink has no referent" and continues (exit 23); we
+         surface the same condition rather than silently dropping the entry. */
+      char* escaped = output_escape(entry->path, log_get_8_bit_output());
+      log_message(LOG_LEVEL_WARNING, "symlink has no referent: %s",
+                  escaped ? escaped : "<allocation failed>");
+      free(escaped);
       goto skip;
     }
-  if (options->copy_unsafe_links && !options->copy_links) {
-    if (link_target[0] != '/')
-      goto skip;
-  }
-
-  bool emit_symlink = false;
-  if (options->copy_links) {
-    emit_symlink = false; /* --copy-links dereferences every referent */
-  } else if (options->safe_links || options->copy_unsafe_links) {
-    emit_symlink = false; /* preserve pre-existing dereference behavior */
-  } else if (options->copy_dirlinks) {
-    struct stat ref;
-    if (stat(entry->path, &ref) == 0 && S_ISDIR(ref.st_mode))
-      emit_symlink = false; /* -k: symlink to a directory recurses as a dir */
-    else
-      emit_symlink = true; /* -k: symlink to a file stays a symlink */
-  } else if (options->follow_symlinks) {
-    emit_symlink = true; /* -l: copy symlink as symlink */
-  }
-
-  if (!emit_symlink) {
-    if (stat(entry->path, &entry->stats) != 0)
-      goto skip;
     entry->is_directory = S_ISDIR(entry->stats.st_mode);
     if (entry->is_directory)
       return 1;
     goto apply_filters;
+  case LINK_ACTION_CARRY:
+    break;
   }
 
-  /* Carry the link as a symlink.  --munge-links containment: a target that
-     could escape the receive root (absolute or containing "..") is never
-     transmitted -- the entry is merely skipped ("contained"). */
-  if (link_target[0] == '\0' ||
-      (options->munge_links && !file_symlink_target_contained(link_target)))
-    goto skip;
+  /* Carry the link as a symlink.  --munge-links is applied by the RECEIVER (it
+     prefixes every stored target with /rsyncd-munged/); when the SOURCE already
+     holds a munged value the sender strips it so the receiver re-munges a clean
+     target, round-tripping a munged tree exactly like rsync. */
   entry->is_symlink = true;
   entry->stats = link_stats;
   entry->is_directory = false;
-  entry->link_target =
-      options->munge_links ? file_symlink_munge(link_target) : str_dup(link_target);
+  entry->link_target = str_dup(link_target);
   if (!entry->link_target)
     goto skip;
+  if (options->munge_links)
+    file_symlink_unmunge(entry->link_target);
   goto apply_filters;
 
 regular:
@@ -798,30 +821,57 @@ static File* dirs_file_for_entry(DirectoryScanner* scanner, const char* entry) {
     return NULL;
   }
   struct stat effective = link_stats;
+  bool emit_symlink = false;
+  char* symlink_target = NULL;
   if (S_ISLNK(link_stats.st_mode)) {
-    /* A symlink is transferred (following its referent) only when a link
-       resolution option is active, mirroring the regular scanner. */
-    bool resolve = scanner->options.follow_symlinks || scanner->options.copy_links ||
-                   scanner->options.safe_links || scanner->options.copy_unsafe_links;
-    if (!resolve || stat(abs_path, &effective) != 0) {
+    /* Resolve the listed symlink with the same precedence as the recursive
+       scanner: dereference or carry the link. */
+    char link_target[4096];
+    LinkAction action =
+        scanner_link_action(&scanner->options, abs_path, entry, link_target, sizeof(link_target));
+    if (action == LINK_ACTION_SKIP || action == LINK_ACTION_SKIP_PROTECTED) {
       free(abs_path);
       return NULL;
     }
+    if (action == LINK_ACTION_DEREF) {
+      if (stat(abs_path, &effective) != 0) {
+        free(abs_path);
+        return NULL;
+      }
+    } else {
+      emit_symlink = true;
+      symlink_target = str_dup(link_target);
+      if (!symlink_target) {
+        free(abs_path);
+        scanner->failed = true;
+        return NULL;
+      }
+      if (scanner->options.munge_links)
+        file_symlink_unmunge(symlink_target);
+    }
   }
   bool is_dir = S_ISDIR(effective.st_mode);
   bool is_file = S_ISREG(effective.st_mode);
-  if (!is_dir && !is_file) {
+  if (!emit_symlink && !is_dir && !is_file) {
+    free(symlink_target);
     free(abs_path);
     return NULL;
   }
   File* file = file_create(abs_path);
   free(abs_path);
   if (!file) {
+    free(symlink_target);
     scanner->failed = true;
     return NULL;
   }
+  if (emit_symlink) {
+    file->is_symlink = true;
+    file->symlink_target = symlink_target;
+    symlink_target = NULL;
+  } else {
     file->is_dir = is_dir;
     file->data->size = is_file ? (unsigned long long)effective.st_size : 0;
+  }
   if (scanner->relative_mode) {
     file->send_path = str_dup(entry);
     if (!file->send_path) {
@@ -978,8 +1028,14 @@ Chunk* directory_scanner_next(DirectoryScanner* scanner) {
       continue;
 
     ScannerEntry inspected;
-    int inspection = scanner_inspect_entry(&scanner->options, scanner->current_path,
-                                           scanner->current_path, entry->d_name, &inspected);
+    char* link_rel = child_rel_path(scanner->current_rel, entry->d_name);
+    if (!link_rel) {
+      scanner->failed = true;
+      break;
+    }
+    int inspection = scanner_inspect_entry(&scanner->options, scanner->current_path, link_rel,
+                                           entry->d_name, &inspected);
+    free(link_rel);
     if (inspection < 0) {
       scanner->failed = true;
       break;
@@ -1084,9 +1140,16 @@ Chunk* directory_scanner_next(DirectoryScanner* scanner) {
         rel_copy = NULL;
       }
       /* --devices/--specials: a device/FIFO/socket entry marked for preservation
-         becomes a node to recreate (is_special, no data, rdev captured). */
-      scanner_prepare_special(scanner->options.preserve_devices, scanner->options.preserve_specials,
-                              file, &stats);
+         becomes a node to recreate (is_special, no data, rdev captured); an
+         unrequested non-regular entry is skipped (rsync default). */
+      ScannerSpecial special = scanner_prepare_special(scanner->options.preserve_devices,
+                                                       scanner->options.preserve_specials,
+                                                       scanner->options.copy_devices, file, &stats);
+      if (special == SCANNER_SPECIAL_SKIP) {
+        free(rel_copy);
+        file_destroy(file);
+        continue;
+      }
       if (scanner->options.hardlinks && S_ISREG(stats.st_mode))
         scanner_assign_hardlink(scanner, scanner->options.hardlinks, file, &stats);
       if (scanner->options.use_metadata)
@@ -1335,7 +1398,7 @@ static void scan_root_entry(const ScannerOptions* options, const FilterNode* roo
                             ParallelScanner* ps) {
   ScannerEntry inspected;
   int inspection =
-      scanner_inspect_entry(options, root_directory, root_directory, entry->d_name, &inspected);
+      scanner_inspect_entry(options, root_directory, entry->d_name, entry->d_name, &inspected);
   if (inspection < 0) {
     ps->failed = true;
     return;
@@ -1415,7 +1478,13 @@ static void scan_root_entry(const ScannerOptions* options, const FilterNode* roo
     file->send_path = rel;
     rel = NULL;
   }
-  scanner_prepare_special(options->preserve_devices, options->preserve_specials, file, &st);
+  ScannerSpecial special = scanner_prepare_special(
+      options->preserve_devices, options->preserve_specials, options->copy_devices, file, &st);
+  if (special == SCANNER_SPECIAL_SKIP) {
+    free(rel);
+    file_destroy(file);
+    return;
+  }
   if (options->hardlinks && S_ISREG(st.st_mode)) {
     int gid;
     bool is_first;

src/client/usage.c

@@ -277,11 +277,11 @@ void print_usage(void) {
   printf("                      Local receiver policy: never sent to the peer, off by default\n");
   printf("  -l, --links         Copy symlinks as symlinks\n");
   printf("  -L, --copy-links    Transform symlinks into referent files\n");
-  printf("  --safe-links        Skip symlinks that point outside transfer tree\n");
-  printf("  --copy-unsafe-links  Only transform unsafe symlinks into referent files\n");
+  printf("  --safe-links        Skip symlinks whose target points outside the tree\n");
+  printf("  --copy-unsafe-links Copy unsafe symlinks (outside tree) as referent files\n");
   printf("  -k, --copy-dirlinks Transform symlinks to directories into real dirs\n");
   printf("  -K, --keep-dirlinks  Keep an existing symlink-to-dir as that dir\n");
-  printf("  --munge-links       Munge symlink targets on the wire (sender)\n");
+  printf("  --munge-links       Munge stored symlink targets (/rsyncd-munged/) on the receiver\n");
   printf("  -H, --hard-links    Preserve hard-link relationships across the transfer\n");
   printf("  -S, --sparse        Handle sparse files efficiently\n");
   printf(
@@ -289,8 +289,7 @@ void print_usage(void) {
   printf(
       "  --devices           Recreate device nodes on the destination (privileged; skipped when\n");
   printf("                      the receiver lacks CAP_MKNOD)\n");
-  printf("  --specials          Recreate special files (FIFOs) on the destination (sockets "
-         "skipped)\n");
+  printf("  --specials          Recreate special files (FIFOs, sockets) on the destination\n");
   printf("  --copy-devices      Copy a source device's content as a regular file instead\n");
   printf("  --write-devices     Write received data into an existing destination device node\n");
   printf("  --inplace           Update files in-place (no temp+rename)\n");

src/shared/file.c

@@ -415,10 +415,69 @@ bool file_get_trust_sender(void) {
   return file_trust_sender;
 }
 
-/* True when `target` is a lexical symlink target that can never escape the
- * receive root once created beneath it: relative (not absolute) and containing
- * no ".." path component.  Used by --munge-links' sender-side containment: an
- * escaping target is never transmitted (the entry is skipped/contained). */
+/* rsync 3.4.1 unsafe_symlink(): true when `target` (the link's destination
+ * string) points outside the transfer tree rooted at the symlink's own
+ * location.  `link_path` is the symlink's path relative to the top of the
+ * transfer (including its name).  This is a purely lexical test matching
+ * rsync's util1.c: absolute/empty targets are always unsafe; leading "../"
+ * components are counted against the symlink's own directory depth; a ".."
+ * that would climb above the transfer root is unsafe.  rsync 3.4.1 additionally
+ * rejects any INTERNAL "/../" component and a trailing "/..". */
+bool file_symlink_unsafe(const char* target, const char* link_path) {
+  if (!target || target[0] == '\0' || target[0] == '/')
+    return true;
+  const char* rest = target;
+  while (strncmp(rest, "../", 3) == 0) {
+    rest += 3;
+    while (*rest == '/')
+      rest++;
+  }
+  if (strstr(rest, "/../") != NULL)
+    return true;
+  size_t target_len = strlen(target);
+  if (target_len > 3 && strcmp(&target[target_len - 3], "/..") == 0)
+    return true;
+
+  int depth = 0;
+  const char* name;
+  const char* slash;
+  const char* src = link_path ? link_path : "";
+  for (name = src; (slash = strchr(name, '/')) != NULL; name = slash + 1) {
+    if (*name == '.' && (name[1] == '/' || (name[1] == '.' && name[2] == '/'))) {
+      if (name[1] == '.')
+        depth = 0;
+    } else {
+      depth++;
+    }
+    while (slash[1] == '/')
+      slash++;
+  }
+  if (*name == '.' && name[1] == '.' && name[2] == '\0')
+    depth = 0;
+
+  for (name = target; (slash = strchr(name, '/')) != NULL; name = slash + 1) {
+    if (*name == '.' && (name[1] == '/' || (name[1] == '.' && name[2] == '/'))) {
+      if (name[1] == '.') {
+        if (--depth < 0)
+          return true;
+      }
+    } else {
+      depth++;
+    }
+    while (slash[1] == '/')
+      slash++;
+  }
+  if (*name == '.' && name[1] == '.' && name[2] == '\0')
+    depth--;
+  return depth < 0;
+}
+
+/* Strict lexical helper: true when `target` is relative (not absolute) and
+ * contains no ".." component at all, so it can never escape the directory it
+ * is created in.  This is stricter than rsync's unsafe_symlink() (which allows
+ * an in-tree ".."); the scanner/receiver use file_symlink_unsafe()/--safe-links
+ * for rsync parity, and this helper is retained for callers that want the
+ * ".."-free guarantee. */
 bool file_symlink_target_contained(const char* target) {
   if (!target || target[0] == '\0' || target[0] == '/')
     return false;
@@ -449,8 +508,9 @@ bool file_symlink_unmunge(char* target) {
   return true;
 }
 
-/* Owned copy of `target` prefixed with SYMLINK_MUNGE_PREFIX (the sender-side
- * --munge-links rewriting).  Returns NULL on allocation failure. */
+/* Owned copy of `target` prefixed with SYMLINK_MUNGE_PREFIX (the receiver-side
+ * --munge-links rewriting, matching rsync's receiver).  Returns NULL on
+ * allocation failure. */
 char* file_symlink_munge(const char* target) {
   if (!target)
     return NULL;
@@ -471,23 +531,14 @@ char* file_symlink_munge(const char* target) {
  * the target is ever followed.  The final component is never dereferenced: an
  * existing non-directory entry at `path` is unlinked by name before the link is
  * placed; an existing directory there is left untouched (returns false, so a
- * caller can treat it as a collision).  As a receiver-side trust-boundary
- * invariant, `target` must be file_symlink_target_contained() (relative and
- * ".."-free): an absolute or escaping target is rejected outright (returns
- * false) so a malicious sender can never materialize a symlink that points
- * outside the receive root. */
+ * caller can treat it as a collision).  The link VALUE `target` is copied
+ * verbatim, matching rsync -l (which stores absolute and ".."-bearing targets
+ * as-is); target policy is the caller's job -- the scanner applies
+ * --safe-links/--copy-unsafe-links, and the receiver applies --munge-links.
+ * The PLACEMENT path is always confined below the authorized root. */
 bool file_symlink_at_secure(const char* path, const char* target) {
-  /* The link itself (`path`) is always kept below the authorized root.  The
-     TARGET may point anywhere: normally only a contained (relative, ".."-free)
-     target is permitted so a malicious sender can never plant a symlink that
-     later dereferences outside the root.  Under --trust-sender that target
-     containment check is relaxed (the receiver trusts the sender and copies the
-     link verbatim, matching rsync -l), but path/leaf confinement is never
-     disabled, so the link still cannot be placed outside the tree. */
   if (!path || !target || has_path_traversal(path))
     return false;
-  if (!file_trust_sender && !file_symlink_target_contained(target))
-    return false;
   char* leaf = NULL;
   int parent_fd = file_open_secure_parent(path, &leaf, true);
   if (parent_fd < 0)

src/shared/file.h

@@ -44,12 +44,20 @@ int file_open_for_read(const char* path);
 bool file_write_to_disk(const char* path, const void* data, unsigned long long data_size,
                         bool inplace, bool sparse);
 
-/* Symlink trust-boundary helpers (Phase 4, symlink wave).  --munge-links
- * sender-side marker: every transmitted symlink target is prefixed with this
- * while the flag is on; the receiver strips it to restore the real target. */
-#define SYMLINK_MUNGE_PREFIX "#SYMLINK/"
+/* Symlink trust-boundary helpers (Phase 4, symlink wave; rsync parity).
+ * --munge-links is a RECEIVER-side rewrite: rsync prefixes every stored symlink
+ * target with this marker, making the link unusable while the referenced
+ * directory does not exist.  A SENDER receiving a munged source strips it back
+ * off before transmitting (so a munged tree round-trips through the receiver's
+ * re-munging). */
+#define SYMLINK_MUNGE_PREFIX "/rsyncd-munged/"
 
 char* file_symlink_munge(const char* target);
+/* rsync 3.4.1 unsafe_symlink(): true when `target` escapes the transfer tree
+ * rooted at `link_path` (the symlink's transfer-relative path incl. its name).
+ * Absolute/empty targets and targets climbing above the transfer root (via
+ * "..") are unsafe, as are internal "/../" components and trailing "/..". */
+bool file_symlink_unsafe(const char* target, const char* link_path);
 /* True when a lexical target is relative and contains no ".." component, so it
  * can never escape the receive root once created beneath it. */
 bool file_symlink_target_contained(const char* target);
@@ -57,8 +65,9 @@ bool file_symlink_target_contained(const char* target);
  * returns true when a marker was removed. */
 bool file_symlink_unmunge(char* target);
 /* Create a symlink at `path` -> `target`, confined below the authorized root
- * (O_NOFOLLOW parent walk, symlinkat; the target is never followed).  Returns
- * false when a directory already occupies `path`. */
+ * (O_NOFOLLOW parent walk, symlinkat; the target is never followed).  The link
+ * value is copied verbatim (rsync -l); only the placement path is confined.
+ * Returns false when a directory already occupies `path`. */
 bool file_symlink_at_secure(const char* path, const char* target);
 /* --keep-dirlinks (-K) receiver process-wide policy: allow an in-root existing
  * symlink-to-directory to be followed as a directory. */

src/shared/file_receive.c

@@ -358,14 +358,6 @@ static FileSaveResult file_save_special_to_disk(const char* root_directory, cons
     log_message(LOG_LEVEL_ERROR, "Special node has no device/FIFO/socket mode");
     return FILE_SAVE_ERROR;
   }
-  if (is_sock) {
-    /* No standard filesystem call recreates a socket; best-effort unsupported. */
-    char* escaped_path = output_escape(file->path, log_get_8_bit_output());
-    log_message(LOG_LEVEL_WARNING, "socket not recreated: %s (unsupported; skipped)",
-                escaped_path ? escaped_path : "<allocation failed>");
-    free(escaped_path);
-    return FILE_SAVE_SKIPPED;
-  }
   if (is_char || is_blk) {
     if (!config || !config->preserve_devices)
       return FILE_SAVE_SKIPPED;
@@ -383,7 +375,10 @@ static FileSaveResult file_save_special_to_disk(const char* root_directory, cons
       free(escaped_path);
       return FILE_SAVE_SKIPPED;
     }
-  } else if (is_fifo) {
+  } else if (is_fifo || is_sock) {
+    /* FIFOs and unix sockets are recreated by --specials.  mknod(S_IFSOCK)
+       works unprivileged on Linux (the node carries no live socket), so unlike
+       a socket bound to a live fd it can be materialized. */
     if (!config || !config->preserve_specials)
       return FILE_SAVE_SKIPPED;
   }
@@ -433,9 +428,12 @@ static FileSaveResult file_save_special_to_disk(const char* root_directory, cons
   } else if (is_blk) {
     create_mode = S_IFBLK;
     rdev = makedev((unsigned)file->rdev_major, (unsigned)file->rdev_minor);
+  } else if (is_sock) {
+    create_mode = S_IFSOCK;
   } else {
     create_mode = S_IFIFO;
   }
+  const char* node_kind = (is_char || is_blk) ? "device" : (is_fifo ? "FIFO" : "socket");
   /* The creation permission bits come from the source only under -p/--perms;
    * otherwise a safe default (0644, group/other write never granted) keeps an
    * unprivileged no--p run from materializing a world-writable node. */
@@ -450,7 +448,7 @@ static FileSaveResult file_save_special_to_disk(const char* root_directory, cons
       struct stat st;
       if (fstatat(parent_fd, leaf, &st, AT_SYMLINK_NOFOLLOW) == 0 &&
           ((is_char && S_ISCHR(st.st_mode)) || (is_blk && S_ISBLK(st.st_mode)) ||
-           (is_fifo && S_ISFIFO(st.st_mode)))) {
+           (is_fifo && S_ISFIFO(st.st_mode)) || (is_sock && S_ISSOCK(st.st_mode)))) {
         close(parent_fd);
         free(leaf);
         free(destination);
@@ -458,7 +456,7 @@ static FileSaveResult file_save_special_to_disk(const char* root_directory, cons
       }
       char* escaped_path = output_escape(file->path, log_get_8_bit_output());
       log_message(LOG_LEVEL_WARNING, "refusing to replace existing entry with %s: %s (skipped)",
-                  is_fifo ? "FIFO" : "device", escaped_path ? escaped_path : "<allocation failed>");
+                  node_kind, escaped_path ? escaped_path : "<allocation failed>");
       free(escaped_path);
     } else if (errno == EPERM || errno == EACCES) {
       /* Missing CAP_MKNOD / parent write permission: the environment cannot
@@ -467,14 +465,12 @@ static FileSaveResult file_save_special_to_disk(const char* root_directory, cons
       log_message(LOG_LEVEL_WARNING,
                   "skipping %s: cannot create %s node (%s)\n"
                   "  --devices/--specials node creation needs privilege (CAP_MKNOD)",
-                  escaped_path ? escaped_path : "<allocation failed>", is_fifo ? "FIFO" : "device",
-                  strerror(errno));
+                  escaped_path ? escaped_path : "<allocation failed>", node_kind, strerror(errno));
       free(escaped_path);
     } else {
       char* escaped_path = output_escape(file->path, log_get_8_bit_output());
-      log_message(LOG_LEVEL_WARNING, "failed to create %s %s: %s (skipped)",
-                  is_fifo ? "FIFO" : "device", escaped_path ? escaped_path : "<allocation failed>",
-                  strerror(errno));
+      log_message(LOG_LEVEL_WARNING, "failed to create %s %s: %s (skipped)", node_kind,
+                  escaped_path ? escaped_path : "<allocation failed>", strerror(errno));
       free(escaped_path);
     }
     close(parent_fd);
@@ -710,26 +706,23 @@ FileSaveResult file_save_to_disk_full(const char* root_directory, const File* fi
     char* link_path = path_cat(root_directory, file->path);
     if (!link_path)
       return FILE_SAVE_ERROR;
-    /* Restore the real target by stripping the sender's --munge-links marker.
-       Only unmunge when the policy was negotiated: a plain -l run must preserve
-       a source symlink whose target genuinely begins with the marker verbatim. */
+    /* The link value is stored verbatim (rsync -l parity: absolute and
+       ".."-bearing targets are preserved; the scanner's --safe-links /
+       --copy-unsafe-links decide which links are sent at all).  --munge-links
+       is a RECEIVER-side rewrite: the stored target is prefixed with
+       /rsyncd-munged/, making the link unusable while the referenced directory
+       does not exist -- exactly as rsync's receiver munges.  Only the link's
+       own placement path is confined below the receive root. */
+    bool munge = config && config->munge_links;
     char* target = str_dup(file->symlink_target);
     bool ok = target != NULL;
-    if (ok && config && config->munge_links)
-      file_symlink_unmunge(target);
-    /* Receiver-side trust boundary (independent of the sender): a target that
-       could escape the receive root (absolute, or relative-with-"..") is never
-       materialized.  It is contained (the entry is skipped) rather than failing
-       the whole transfer, so a hostile sender can inject a broken symlink but
-       can never redirect it outside the root.  --trust-sender deliberately
-       relaxes this receiver-side re-validation: a trusted sender's escaping
-       symlink target is copied verbatim (rsync -l parity).  The low-level
-       leaf/destination confinement in file_symlink_at_secure still ensures the
-       link itself is placed inside the authorized root. */
-    if (ok && !file_get_trust_sender() && !file_symlink_target_contained(target))
-      ok = false;
+    if (ok && munge) {
+      char* munged = file_symlink_munge(target);
+      free(target);
+      target = munged;
+      ok = target != NULL;
+    }
     if (!ok) {
-      /* Skip the escaping/empty target (contained) rather than abort. */
       free(target);
       free(link_path);
       return FILE_SAVE_SKIPPED;

tests/integration/test_features.py

@@ -92,54 +92,63 @@ class TestDeviceSpecial:
         assert stat.S_ISFIFO(os.stat(os.path.join(received, "pipe.fifo")).st_mode)
 
     @pytest.mark.ci
-    def test_specials_socket_source_skipped_safely(self):
-        """A socket cannot be recreated by any standard filesystem call, so
-        --specials must skip it with a note and still complete the run (the
-        adjacent regular file transfers normally; no socket node appears)."""
+    def test_specials_recreates_socket(self, shared_server):
+        """--specials recreates a unix-domain socket with mknod(S_IFSOCK), which
+        Linux permits unprivileged; the adjacent regular file still transfers."""
         self._setup()
         sock_path = os.path.join(DEVICE_SOURCE, "source.sock")
         s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-        server, port = _start_captured_server()
         try:
             s.bind(sock_path)
             result, _ = run_client(DEVICE_SOURCE, DEVICE_DEST,
-                                   flags=["--specials"], port=port)
+                                   flags=["--specials"], port=shared_server.port)
         finally:
             s.close()
-            out, err = _stop_captured_server(server)
         assert result.returncode == 0, f"Exit {result.returncode}: {result.stderr[:200]}"
         received = get_dest_received_dir(DEVICE_DEST, DEVICE_SOURCE)
         with open(os.path.join(received, "plain.txt")) as f:
             assert f.read() == "regular content\n"
-        assert not os.path.lexists(os.path.join(received, "source.sock")), (
-            "socket source must be skipped, not materialized"
-        )
-        assert "socket not recreated" in (out + err), (
-            f"receiver did not log the documented socket skip: out={out!r} err={err!r}"
+        dest_sock = os.path.join(received, "source.sock")
+        assert os.path.lexists(dest_sock), "socket source was not recreated"
+        assert stat.S_ISSOCK(os.lstat(dest_sock).st_mode), (
+            "socket source must be recreated as a socket node"
         )
 
+    @pytest.mark.ci
+    def test_special_default_skips_non_regular(self, shared_server):
+        """Without --specials, rsync skips a FIFO/socket as a non-regular file;
+        FastSync must skip it (never copy it as an empty regular file)."""
+        self._setup()
+        os.mkfifo(os.path.join(DEVICE_SOURCE, "skip.fifo"))
+        sock_path = os.path.join(DEVICE_SOURCE, "skip.sock")
+        s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+        try:
+            s.bind(sock_path)
+            result, _ = run_client(DEVICE_SOURCE, DEVICE_DEST, flags=[], port=shared_server.port)
+        finally:
+            s.close()
+        assert result.returncode == 0, f"Exit {result.returncode}: {result.stderr[:200]}"
+        received = get_dest_received_dir(DEVICE_DEST, DEVICE_SOURCE)
+        assert not os.path.lexists(os.path.join(received, "skip.fifo"))
+        assert not os.path.lexists(os.path.join(received, "skip.sock"))
+        with open(os.path.join(received, "plain.txt")) as f:
+            assert f.read() == "regular content\n"
+
     @pytest.mark.ci
     @pytest.mark.parametrize("flags", [["--copy-devices"], ["--copy-devices", "--sendfile"]])
-    def test_copy_devices_fifo_becomes_regular_file(self, shared_server, flags):
-        """--copy-devices treats a special source as an ordinary regular-file
-        copy: a FIFO (st_size 0) becomes a zero-length REGULAR file on the
-        destination (never a FIFO, never a hang), and the run succeeds.  The
-        --sendfile variant previously blocked forever in the sendfile open();
-        the non-regular source now falls back to the buffered read path, so it
-        must complete within the bounded-time assertion below."""
+    def test_copy_devices_skips_fifo_without_specials(self, shared_server, flags):
+        """rsync's --copy-devices applies to device nodes only; a FIFO/socket is
+        a non-regular entry and is skipped unless --specials is also given.  In
+        particular it must never hang in the sendfile open()."""
         self._setup()
         os.mkfifo(os.path.join(DEVICE_SOURCE, "device_copy.fifo"))
         result, dur = run_client(DEVICE_SOURCE, DEVICE_DEST,
                                  flags=flags, port=shared_server.port)
         assert result.returncode == 0, f"Exit {result.returncode}: {result.stderr[:200]}"
         received = get_dest_received_dir(DEVICE_DEST, DEVICE_SOURCE)
-        copied = os.path.join(received, "device_copy.fifo")
-        assert os.path.lexists(copied), "copy-devices source was not transferred"
-        st = os.lstat(copied)
-        assert stat.S_ISREG(st.st_mode), (
-            f"copy-devices must produce a regular file, got mode {oct(st.st_mode)}"
+        assert not os.path.lexists(os.path.join(received, "device_copy.fifo")), (
+            "a FIFO under --copy-devices alone must be skipped, not materialized"
         )
-        assert st.st_size == 0, f"expected a size-bounded 0-byte copy, got {st.st_size}"
         assert dur < 60, f"{' '.join(flags)} hung on a FIFO source"
 
     def test_write_devices_non_crash(self, shared_server):
@@ -220,6 +229,24 @@ class TestDeviceSpecial:
         assert stat.S_ISCHR(st.st_mode)
         assert os.major(st.st_rdev) == 1 and os.minor(st.st_rdev) == 3
 
+    @pytest.mark.skipif(os.geteuid() != 0, reason="requires root to create device nodes")
+    def test_copy_devices_copies_device_as_regular(self, shared_server):
+        """Root-only: --copy-devices copies a device's content into an ordinary
+        regular file instead of recreating the node.  /dev/null (1,3) has size 0,
+        so the result is a 0-byte REGULAR file."""
+        self._setup()
+        src_dev = os.path.join(DEVICE_SOURCE, "copieddev")
+        os.mknod(src_dev, stat.S_IFCHR | 0o666, os.makedev(1, 3))
+        result, _ = run_client(DEVICE_SOURCE, DEVICE_DEST,
+                               flags=["-a", "--copy-devices"], port=shared_server.port)
+        assert result.returncode == 0, f"Exit {result.returncode}: {result.stderr[:200]}"
+        received = get_dest_received_dir(DEVICE_DEST, DEVICE_SOURCE)
+        st = os.lstat(os.path.join(received, "copieddev"))
+        assert stat.S_ISREG(st.st_mode), (
+            f"--copy-devices must produce a regular file, got mode {oct(st.st_mode)}"
+        )
+        assert st.st_size == 0
+
     def test_m_remove_source_files_keeps_recreated_fifo(self, shared_server):
         """--threads --remove-source-files --specials: a recreated FIFO must NOT be
         acknowledged as a removable source (its outcome must not shift the
@@ -5150,8 +5177,10 @@ class TestSymlinkTrust:
         os.symlink("realfile.txt", os.path.join(source, "link_file"))
         os.symlink("realdir", os.path.join(source, "link_dir"))
 
-        result, _ = run_client(source, dest, flags=["-k"], port=shared_server.port)
-        assert result.returncode == 0, f"-k failed: {(result.stderr or result.stdout)[:300]}"
+        # -k only dereferences directory symlinks; file symlinks need -l to be
+        # carried as symlinks (rsync skips them otherwise).
+        result, _ = run_client(source, dest, flags=["-l", "-k"], port=shared_server.port)
+        assert result.returncode == 0, f"-l -k failed: {(result.stderr or result.stdout)[:300]}"
 
         received = get_dest_received_dir(dest, source)
         # link -> realdir dereferences into a real directory tree...
@@ -5191,9 +5220,13 @@ class TestSymlinkTrust:
         # ... and the file is written beneath it, through to the referent dir.
         assert os.path.isfile(os.path.join(parent, "realdir", "file.txt"))
 
-    def test_munge_links_unmunged_target_and_containment(self, shared_server):
-        source = os.path.join(TEST_DATA_DIR, "symlink_trust_munge")
-        dest = os.path.join(TEST_DATA_DIR, "symlink_trust_munge_dst")
+    @pytest.mark.ci
+    def test_munge_links_prefixes_targets(self, shared_server):
+        # rsync's --munge-links is a RECEIVER-side rewrite: every stored target
+        # gets the /rsyncd-munged/ prefix, making the link unusable while that
+        # directory does not exist.
+        source = os.path.join(TEST_DATA_DIR, "symlink_munge")
+        dest = os.path.join(TEST_DATA_DIR, "symlink_munge_dst")
         clean_dir(source)
         clean_dir(dest)
         with open(os.path.join(source, "a.txt"), "wb") as f:
@@ -5207,19 +5240,15 @@ class TestSymlinkTrust:
         assert result.returncode == 0, f"--munge-links failed: {(result.stderr or result.stdout)[:300]}"
 
         received = get_dest_received_dir(dest, source)
-        # The safe symlink is created with its correct (unmunged) target.
-        good = os.path.join(received, "good")
-        assert os.path.islink(good)
-        assert os.readlink(good) == "a.txt"
-        # A target that would escape the receive root is contained (skip: never
-        # transmitted, so nothing is created at the destination).
-        assert not os.path.lexists(os.path.join(received, "abs_escape"))
-        assert not os.path.lexists(os.path.join(received, "dotdot_escape"))
+        assert os.readlink(os.path.join(received, "good")) == "/rsyncd-munged/a.txt"
+        assert os.readlink(os.path.join(received, "abs_escape")) == "/rsyncd-munged//etc/passwd"
+        assert os.readlink(os.path.join(received, "dotdot_escape")) == "/rsyncd-munged/../../escape"
         assert os.path.isfile(os.path.join(received, "a.txt"))
 
+    @pytest.mark.ci
     def test_links_copies_symlinks_as_symlinks(self, shared_server):
-        source = os.path.join(TEST_DATA_DIR, "symlink_trust_links")
-        dest = os.path.join(TEST_DATA_DIR, "symlink_trust_links_dst")
+        source = os.path.join(TEST_DATA_DIR, "symlink_links")
+        dest = os.path.join(TEST_DATA_DIR, "symlink_links_dst")
         clean_dir(source)
         clean_dir(dest)
         os.makedirs(os.path.join(source, "realdir"))
@@ -5238,48 +5267,157 @@ class TestSymlinkTrust:
         assert os.path.islink(os.path.join(received, "ld"))
         assert os.readlink(os.path.join(received, "ld")) == "realdir"
 
-    def test_receiver_contains_absolute_target_even_without_munge(self, shared_server):
-        # The trust boundary is symmetric and enforced receiver-side: a plain -l
-        # (no --munge-links) run must refuse to materialize an out-of-root
-        # absolute symlink target, while still copying a legitimate in-root one.
-        source = os.path.join(TEST_DATA_DIR, "symlink_trust_abs")
-        dest = os.path.join(TEST_DATA_DIR, "symlink_trust_abs_dst")
+    @pytest.mark.ci
+    def test_links_preserves_absolute_and_dotdot_targets(self, shared_server):
+        # rsync -l parity: -l stores a symlink target verbatim, including an
+        # absolute target and an in-tree ".." target (no silent drop).
+        source = os.path.join(TEST_DATA_DIR, "symlink_links_verbatim")
+        dest = os.path.join(TEST_DATA_DIR, "symlink_links_verbatim_dst")
         clean_dir(source)
         clean_dir(dest)
         with open(os.path.join(source, "a.txt"), "wb") as f:
             f.write(b"a\n")
+        os.makedirs(os.path.join(source, "sub"))
         os.symlink("a.txt", os.path.join(source, "good"))
         os.symlink("/etc/passwd", os.path.join(source, "unsafe_abs"))
+        os.symlink("../a.txt", os.path.join(source, "sub", "up"))
 
         result, _ = run_client(source, dest, flags=["-l"], port=shared_server.port)
         assert result.returncode == 0, f"-l failed: {(result.stderr or result.stdout)[:300]}"
-
         received = get_dest_received_dir(dest, source)
-        good = os.path.join(received, "good")
-        assert os.path.islink(good)
-        assert os.readlink(good) == "a.txt"
-        # The absolute (non-contained) target was not materialized at the dest.
-        assert not os.path.lexists(os.path.join(received, "unsafe_abs"))
+        assert os.readlink(os.path.join(received, "good")) == "a.txt"
+        assert os.readlink(os.path.join(received, "unsafe_abs")) == "/etc/passwd"
+        assert os.readlink(os.path.join(received, "sub", "up")) == "../a.txt"
 
-    def test_links_does_not_strip_munge_prefix_without_munge(self, shared_server):
-        # A source symlink whose target genuinely begins with the #SYMLINK/ marker
-        # must round-trip verbatim under plain -l: the receiver only unmunges when
-        # the negotiated --munge-links policy is on, never unconditionally.
-        source = os.path.join(TEST_DATA_DIR, "symlink_trust_prefix")
-        dest = os.path.join(TEST_DATA_DIR, "symlink_trust_prefix_dst")
+    @pytest.mark.ci
+    def test_safe_links_keeps_safe_skips_unsafe(self, shared_server):
+        # --safe-links keeps symlinks that stay inside the transfer tree (even
+        # with a ".." that does not climb out) and drops absolute / escaping /
+        # internally-".."-bearing targets.
+        source = os.path.join(TEST_DATA_DIR, "symlink_safe")
+        dest = os.path.join(TEST_DATA_DIR, "symlink_safe_dst")
+        clean_dir(source)
+        clean_dir(dest)
+        with open(os.path.join(source, "a.txt"), "wb") as f:
+            f.write(b"a\n")
+        os.makedirs(os.path.join(source, "sub"))
+        os.symlink("a.txt", os.path.join(source, "safe_rel"))
+        os.symlink("../a.txt", os.path.join(source, "sub", "up"))
+        os.symlink("/etc/passwd", os.path.join(source, "abs"))
+        os.symlink("../outside.txt", os.path.join(source, "esc"))
+        os.symlink("sub/../a.txt", os.path.join(source, "internal"))
+
+        result, _ = run_client(source, dest, flags=["-l", "--safe-links"],
+                               port=shared_server.port)
+        assert result.returncode == 0, f"--safe-links failed: {(result.stderr or result.stdout)[:300]}"
+        received = get_dest_received_dir(dest, source)
+        assert os.readlink(os.path.join(received, "safe_rel")) == "a.txt"
+        assert os.readlink(os.path.join(received, "sub", "up")) == "../a.txt"
+        for unsafe in ("abs", "esc", "internal"):
+            assert not os.path.lexists(os.path.join(received, unsafe)), (
+                f"{unsafe} must be skipped by --safe-links"
+            )
+
+    @pytest.mark.ci
+    def test_safe_links_protects_dest_from_delete(self):
+        # rsync counts an unsafe link ignored by --safe-links as present in the
+        # transfer, so its destination mirror survives --delete.  FastSync must
+        # not delete it (no silent data loss).  Own server: deletion needs
+        # --allow-delete, which the shared session server does not grant.
+        source = os.path.join(TEST_DATA_DIR, "symlink_safe_delete")
+        dest = os.path.join(TEST_DATA_DIR, "symlink_safe_delete_dst")
+        clean_dir(source)
+        clean_dir(dest)
+        with open(os.path.join(source, "keep.txt"), "wb") as f:
+            f.write(b"keep\n")
+        os.symlink("/etc/passwd", os.path.join(source, "unsafe_abs"))
+
+        with ServerManager() as server:
+            server.start(extra_args=["--allow-delete"])
+            received = get_dest_received_dir(dest, source)
+            os.makedirs(received, exist_ok=True)
+            mirror = os.path.join(received, "unsafe_abs")
+            with open(mirror, "wb") as f:
+                f.write(b"existing destination data\n")
+            extra = os.path.join(received, "extra.txt")
+            with open(extra, "wb") as f:
+                f.write(b"extra\n")
+
+            result, _ = run_client(source, dest, flags=["-l", "--safe-links", "--delete"],
+                                   port=server.port)
+            assert result.returncode == 0, (
+                f"--delete --safe-links failed: {(result.stderr or result.stdout)[:300]}"
+            )
+            assert os.path.exists(mirror), (
+                "a destination mirror of a --safe-links-skipped link must survive --delete"
+            )
+            assert not os.path.exists(extra), "a genuine extra must still be deleted"
+
+    @pytest.mark.ci
+    def test_copy_unsafe_links_derefs_only_unsafe(self, shared_server):
+        # --copy-unsafe-links keeps safe symlinks and dereferences unsafe ones
+        # (absolute or escaping) into regular files.
+        source = os.path.join(TEST_DATA_DIR, "symlink_copy_unsafe")
+        dest = os.path.join(TEST_DATA_DIR, "symlink_copy_unsafe_dst")
+        clean_dir(source)
+        clean_dir(dest)
+        with open(os.path.join(source, "a.txt"), "wb") as f:
+            f.write(b"a\n")
+        with open(os.path.join(source, "refer.txt"), "wb") as f:
+            f.write(b"refer\n")
+        external = os.path.join(TEST_DATA_DIR, "symlink_copy_unsafe_external.txt")
+        with open(external, "wb") as f:
+            f.write(b"external\n")
+        os.symlink("a.txt", os.path.join(source, "safe_rel"))
+        os.symlink("refer.txt", os.path.join(source, "from_rel"))
+        os.symlink("../symlink_copy_unsafe_external.txt", os.path.join(source, "esc"))
+        os.symlink("/etc/hostname", os.path.join(source, "abs"))
+
+        result, _ = run_client(source, dest, flags=["-l", "--copy-unsafe-links"],
+                               port=shared_server.port)
+        assert result.returncode == 0, (
+            f"--copy-unsafe-links failed: {(result.stderr or result.stdout)[:300]}"
+        )
+        received = get_dest_received_dir(dest, source)
+        assert os.path.islink(os.path.join(received, "safe_rel"))
+        assert os.readlink(os.path.join(received, "safe_rel")) == "a.txt"
+        assert os.path.islink(os.path.join(received, "from_rel")), (
+            "a safe symlink must be preserved, not dereferenced"
+        )
+        assert os.readlink(os.path.join(received, "from_rel")) == "refer.txt"
+        # An escaping (..) symlink and an absolute symlink are both dereferenced
+        # into regular files holding the referent's content.
+        assert not os.path.islink(os.path.join(received, "esc"))
+        with open(os.path.join(received, "esc"), "rb") as f:
+            assert f.read() == b"external\n"
+        assert not os.path.islink(os.path.join(received, "abs"))
+        assert os.path.isfile(os.path.join(received, "abs"))
+
+    def test_munge_prefix_roundtrip(self, shared_server):
+        # A source target that already begins with /rsyncd-munged/ round-trips:
+        # plain -l stores it verbatim, and --munge-links strips on the sender
+        # then re-munges on the receiver, yielding the same stored value.
+        source = os.path.join(TEST_DATA_DIR, "symlink_munge_roundtrip")
+        dest = os.path.join(TEST_DATA_DIR, "symlink_munge_roundtrip_dst")
         clean_dir(source)
         clean_dir(dest)
         with open(os.path.join(source, "realfile.txt"), "wb") as f:
             f.write(b"real\n")
-        os.symlink("#SYMLINK/realfile.txt", os.path.join(source, "prefixed"))
-
-        result, _ = run_client(source, dest, flags=["-l"], port=shared_server.port)
-        assert result.returncode == 0, f"-l failed: {(result.stderr or result.stdout)[:300]}"
+        os.symlink("/rsyncd-munged/realfile.txt", os.path.join(source, "prefixed"))
+        os.symlink("#SYMLINK/realfile.txt", os.path.join(source, "oldmarker"))
 
+        for flags, oldmarker_target in (
+            (["-l"], "#SYMLINK/realfile.txt"),
+            (["-l", "--munge-links"], "/rsyncd-munged/#SYMLINK/realfile.txt"),
+        ):
+            clean_dir(dest)
+            result, _ = run_client(source, dest, flags=flags, port=shared_server.port)
+            assert result.returncode == 0, (
+                f"{' '.join(flags)} failed: {(result.stderr or result.stdout)[:300]}"
+            )
             received = get_dest_received_dir(dest, source)
-        prefixed = os.path.join(received, "prefixed")
-        assert os.path.islink(prefixed)
-        assert os.readlink(prefixed) == "#SYMLINK/realfile.txt"
+            assert os.readlink(os.path.join(received, "prefixed")) == "/rsyncd-munged/realfile.txt"
+            assert os.readlink(os.path.join(received, "oldmarker")) == oldmarker_target
 def _xattr_supported(path):
     """True when the filesystem hosting `path` supports user xattrs."""
     try:

tests/test_file.c

@@ -518,6 +518,20 @@ static void test_file_symlink_helpers() {
   EXPECT_FALSE(file_symlink_target_contained("../escape"));
   EXPECT_FALSE(file_symlink_target_contained("a/../b"));
   EXPECT_FALSE(file_symlink_target_contained(""));
+
+  /* rsync 3.4.1 unsafe_symlink(): absolute/empty are unsafe; ".." is measured
+     against the symlink's own transfer-relative directory depth. */
+  EXPECT_TRUE(file_symlink_unsafe("/etc/passwd", "link"));
+  EXPECT_TRUE(file_symlink_unsafe("", "link"));
+  EXPECT_FALSE(file_symlink_unsafe("a.txt", "link"));
+  EXPECT_FALSE(file_symlink_unsafe("./a.txt", "link"));
+  EXPECT_FALSE(file_symlink_unsafe("../real.txt", "a/up1"));
+  EXPECT_FALSE(file_symlink_unsafe("../../real.txt", "a/b/up3"));
+  EXPECT_TRUE(file_symlink_unsafe("../../../outside", "a/b/esc"));
+  EXPECT_TRUE(file_symlink_unsafe("../outside", "esc"));
+  /* Internal /../ and a trailing /.. are rejected by rsync 3.4.1. */
+  EXPECT_TRUE(file_symlink_unsafe("a/b/../real.txt", "norm"));
+  EXPECT_TRUE(file_symlink_unsafe("dir/..", "link"));
 }
 
 static void test_file_symlink_at_secure() {
@@ -1123,6 +1137,47 @@ static void test_special_fifo_mode_never_group_other_writable() {
   umask(saved_umask);
 }
 
+/* --specials recreates a unix-domain socket via mknod(S_IFSOCK), which Linux
+ * permits unprivileged.  Without --specials the entry is skipped. */
+static void test_special_socket_recreated() {
+  const char* root = "test_special_sock_tmp";
+  const char* sock = "test_special_sock_tmp/source.sock";
+  unlink(sock);
+  rmdir(root);
+  EXPECT_EQ_INT(mkdir(root, 0700), 0);
+
+  Config* cfg = config_create();
+  EXPECT_NOT_NULL(cfg);
+  FileMetadata meta;
+  memset(&meta, 0, sizeof(meta));
+  meta.mode = S_IFSOCK | 0600;
+  meta.uid = geteuid();
+  meta.gid = getegid();
+
+  File* f = file_create("source.sock");
+  EXPECT_NOT_NULL(f);
+  f->is_special = true;
+  f->metadata = &meta;
+  cfg->preserve_specials = true;
+  cfg->use_metadata = true;
+  EXPECT_EQ_INT(file_save_to_disk_full(root, f, cfg), FILE_SAVE_WRITTEN);
+  struct stat st;
+  EXPECT_EQ_INT(lstat(sock, &st), 0);
+  EXPECT_TRUE(S_ISSOCK(st.st_mode));
+
+  /* Without --specials the same entry is skipped, never a regular file. */
+  unlink(sock);
+  cfg->preserve_specials = false;
+  EXPECT_EQ_INT(file_save_to_disk_full(root, f, cfg), FILE_SAVE_SKIPPED);
+  EXPECT_EQ_INT(lstat(sock, &st), -1);
+
+  f->metadata = NULL;
+  file_destroy(f);
+  config_delete(cfg);
+  unlink(sock);
+  rmdir(root);
+}
+
 static void test_inplace_overwrite_truncates_shorter_payload() {
   const char* root = "test_inplace_trunc_tmp";
   const char* path = "test_inplace_trunc_tmp/big.txt";
@@ -1297,34 +1352,27 @@ static void test_dir_entry_save_to_disk() {
  * receiver enables it from its own process (the standalone server's --trust-
  * sender CLI switch, which a client forwards as --remote-option=--trust-sender),
  * so these tests force file_set_trust_sender(true) directly.  Trust must RELAX
- * only the redundant list-level re-validation (an escaping symlink TARGET is
- * copied verbatim, rsync -l parity) and must NEVER disable the low-level
- * fd-relative confinement floor: file_open_secure_parent's ".." rejection, the
- * O_NOFOLLOW parent walk, leaf/destination confinement, and the ungated
- * has_path_traversal on the link's own placement path in file_symlink_at_secure
- * stay hard.  A hostile sender therefore still cannot place a file, directory
- * or symlink outside the receive root even with trust on. */
+ * only the redundant list-level re-validation and must NEVER disable the
+ * low-level fd-relative confinement floor: file_open_secure_parent's ".."
+ * rejection, the O_NOFOLLOW parent walk, leaf/destination confinement, and the
+ * ungated has_path_traversal on the link's own placement path in
+ * file_symlink_at_secure stay hard.  A hostile sender therefore still cannot
+ * place a file, directory or symlink outside the receive root. */
 
-static void test_trust_sender_relaxes_symlink_target() {
-  const char* root = "test_trust_sender_root";
-  const char* link = "test_trust_sender_root/escape_link";
+static void test_symlink_target_verbatim() {
+  const char* root = "test_symlink_verbatim_root";
+  const char* link = "test_symlink_verbatim_root/escape_link";
   unlink(link);
   rmdir(root);
   EXPECT_EQ_INT(mkdir(root, 0755), 0);
 
-  /* Control: without trust an absolute (escaping) target is refused and the
-     link is never placed. */
+  /* rsync -l parity: a symlink target is stored verbatim, absolute or not; the
+     scanner's --safe-links/--copy-unsafe-links is what filters links. */
   file_set_trust_sender(false);
-  EXPECT_FALSE(file_symlink_at_secure(link, "/etc/passwd"));
-  struct stat st;
-  EXPECT_EQ_INT(lstat(link, &st), -1);
-
-  /* Trust ON: the escaping target is copied verbatim (rsync -l parity) ... */
-  file_set_trust_sender(true);
   EXPECT_TRUE(file_symlink_at_secure(link, "/etc/passwd"));
+  struct stat st;
   EXPECT_EQ_INT(lstat(link, &st), 0);
   EXPECT_TRUE(S_ISLNK(st.st_mode));
-  /* ...but the link itself still lands beneath the receive root. */
   char target[128];
   ssize_t target_len = readlink(link, target, sizeof(target) - 1);
   EXPECT_TRUE(target_len > 0);
@@ -1335,10 +1383,10 @@ static void test_trust_sender_relaxes_symlink_target() {
   }
   unlink(link);
 
-  /* Same relaxation through the real save funnel (file_save_to_disk_full). */
+  /* The same through the real save funnel: verbatim by default. */
   Config* config = config_create();
   EXPECT_NOT_NULL(config);
-  const char* save_link = "test_trust_sender_root/save_link";
+  const char* save_link = "test_symlink_verbatim_root/save_link";
   unlink(save_link);
 
   File* sym = file_create("save_link");
@@ -1348,10 +1396,6 @@ static void test_trust_sender_relaxes_symlink_target() {
   EXPECT_NOT_NULL(sym->symlink_target);
 
   file_set_trust_sender(false);
-  EXPECT_EQ_INT(file_save_to_disk_full(root, sym, config), FILE_SAVE_SKIPPED);
-  EXPECT_EQ_INT(lstat(save_link, &st), -1);
-
-  file_set_trust_sender(true);
   EXPECT_EQ_INT(file_save_to_disk_full(root, sym, config), FILE_SAVE_WRITTEN);
   EXPECT_EQ_INT(lstat(save_link, &st), 0);
   EXPECT_TRUE(S_ISLNK(st.st_mode));
@@ -1477,7 +1521,7 @@ void test_trust_sender() {
      helper), so a later group never inherits a stray trust/authorized-root
      policy. */
   file_set_trust_sender(false);
-  test_trust_sender_relaxes_symlink_target();
+  test_symlink_target_verbatim();
   test_trust_sender_confines_hostile_paths();
   test_trust_sender_authorized_root_confinement();
   file_set_trust_sender(false);
@@ -1877,6 +1921,7 @@ void test_file() {
   test_atomic_no_perms_preserves_destination_mode();
   test_new_file_mode_never_group_other_writable();
   test_special_fifo_mode_never_group_other_writable();
+  test_special_socket_recreated();
   test_inplace_overwrite_truncates_shorter_payload();
   test_inplace_refuses_fifo_destination();
   test_inplace_refuses_device_destination();

tests/test_server.c

@@ -818,10 +818,24 @@ static void test_special_socket_path_log_escaped() {
   set_log_level(LOG_LEVEL_WARNING);
   log_set_8_bit_output(false);
 
+  const char* root = "test_special_sock_escape_root";
+  const char* existing = "test_special_sock_escape_root/evil\npath";
+  unlink(existing);
+  rmdir(root);
+  EXPECT_EQ_INT(mkdir(root, 0700), 0);
+  FILE* planted = fopen(existing, "wb");
+  EXPECT_NOT_NULL(planted);
+  fclose(planted);
+
   FILE* capture = tmpfile();
   EXPECT_NOT_NULL(capture);
   log_set_file(capture);
 
+  Config* cfg = config_create();
+  EXPECT_NOT_NULL(cfg);
+  cfg->preserve_specials = true;
+  cfg->use_metadata = true;
+
   File* file = file_create("evil\npath");
   EXPECT_NOT_NULL(file);
   file->is_special = true;
@@ -829,7 +843,9 @@ static void test_special_socket_path_log_escaped() {
   EXPECT_NOT_NULL(file->metadata);
   file->metadata->mode = S_IFSOCK | 0644;
 
-  FileSaveResult result = file_save_to_disk_full("/tmp/dst", file, NULL);
+  /* A non-matching entry already occupies the path: the socket creation is
+     refused and the warning must escape the path's control byte. */
+  FileSaveResult result = file_save_to_disk_full(root, file, cfg);
   EXPECT_EQ_INT(result, FILE_SAVE_SKIPPED);
 
   fflush(capture);
@@ -841,8 +857,11 @@ static void test_special_socket_path_log_escaped() {
   log_set_file(NULL);
   fclose(capture);
   file_destroy(file);
+  config_delete(cfg);
+  unlink(existing);
+  rmdir(root);
 
-  EXPECT_NOT_NULL(strstr(output, "socket not recreated: evil\\#012path"));
+  EXPECT_NOT_NULL(strstr(output, "refusing to replace existing entry with socket: evil\\#012path"));
 }
 
 /* B1: a client-planted FIFO at the destination must not block the receiver's