File rsync-CVE-2022-29154.patch of Package rsync.36811
From b7231c7d02cfb65d291af74ff66e7d8c507ee871 Mon Sep 17 00:00:00 2001
From: Wayne Davison <wayne@opencoder.net>
Date: Sun, 31 Jul 2022 16:55:34 -0700
Subject: [PATCH] Some extra file-list safety checks.
---
exclude.c | 130 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
flist.c | 17 ++++++-
io.c | 4 ++
main.c | 7 ++-
receiver.c | 11 +++--
rsync.1.md | 44 ++++++++++++++++--
6 files changed, 202 insertions(+), 11 deletions(-)
Index: rsync-3.2.3/exclude.c
===================================================================
--- rsync-3.2.3.orig/exclude.c
+++ rsync-3.2.3/exclude.c
@@ -27,16 +27,23 @@ extern int am_server;
extern int am_sender;
extern int eol_nulls;
extern int io_error;
+extern int xfer_dirs;
+extern int recurse;
extern int local_server;
extern int prune_empty_dirs;
extern int ignore_perishable;
+extern int relative_paths;
extern int delete_mode;
extern int delete_excluded;
extern int cvs_exclude;
extern int sanitize_paths;
extern int protocol_version;
+extern int list_only;
extern int module_id;
+extern int local_server;
+
+extern char *filesfrom_host;
extern char curr_dir[MAXPATHLEN];
extern unsigned int curr_dir_len;
extern unsigned int module_dirlen;
@@ -44,8 +51,10 @@ extern unsigned int module_dirlen;
filter_rule_list filter_list = { .debug_type = "" };
filter_rule_list cvs_filter_list = { .debug_type = " [global CVS]" };
filter_rule_list daemon_filter_list = { .debug_type = " [daemon]" };
+filter_rule_list implied_filter_list = { .debug_type = " [implied]" };
int saw_xattr_filter = 0;
+int trust_sender_filter = 0;
/* Need room enough for ":MODS " prefix plus some room to grow. */
#define MAX_RULE_PREFIX (16)
@@ -288,6 +297,143 @@ static void add_rule(filter_rule_list *l
}
}
+/* Each arg the client sends to the remote sender turns into an implied include
+ * that the receiver uses to validate the file list from the sender. */
+void add_implied_include(const char *arg)
+{
+ filter_rule *rule;
+ int arg_len, saw_wild = 0, backslash_cnt = 0;
+ int slash_cnt = 1; /* We know we're adding a leading slash. */
+ const char *cp;
+ char *p;
+
+ int old_style_args = -1;
+
+ /*
+ A local transfer doesn't unbackslash anything, so leave the args alone.
+
+ This check comes from 3.2.4+ main.c check, where the CVE is fixed. In
+ these versions, the protection against the CVE is ran only when a remote
+ server is involved.
+
+ In this version, there is no "old_style_args", as this was not
+ implemented yet, so we relay on detecting if a local server is
+ involved directly and we set a local variable "old_style_args"
+ to not to modify the original patch too much.
+ */
+ if (local_server)
+ old_style_args = 2;
+
+ if (old_style_args || list_only || filesfrom_host != NULL)
+ return;
+ if (relative_paths) {
+ cp = strstr(arg, "/./");
+ if (cp)
+ arg = cp+3;
+ } else {
+ if ((cp = strrchr(arg, '/')) != NULL)
+ arg = cp + 1;
+ }
+ arg_len = strlen(arg);
+ if (arg_len) {
+ if (strpbrk(arg, "*[?")) {
+ /* We need to add room to escape backslashes if wildcard chars are present. */
+ cp = arg;
+ while ((cp = strchr(cp, '\\')) != NULL) {
+ arg_len++;
+ cp++;
+ }
+ saw_wild = 1;
+ }
+ arg_len++; /* Leave room for the prefixed slash */
+ rule = new0(filter_rule);
+ if (!implied_filter_list.head)
+ implied_filter_list.head = implied_filter_list.tail = rule;
+ else {
+ rule->next = implied_filter_list.head;
+ implied_filter_list.head = rule;
+ }
+ rule->rflags = FILTRULE_INCLUDE + (saw_wild ? FILTRULE_WILD : 0);
+ p = rule->pattern = new_array(char, arg_len + 1);
+ *p++ = '/';
+ cp = arg;
+ while (*cp) {
+ switch (*cp) {
+ case '\\':
+ backslash_cnt++;
+ if (saw_wild)
+ *p++ = '\\';
+ *p++ = *cp++;
+ break;
+ case '/':
+ if (p[-1] == '/') /* This is safe because of the initial slash. */
+ break;
+ if (relative_paths) {
+ filter_rule const *ent;
+ int found = 0;
+ *p = '\0';
+ for (ent = implied_filter_list.head; ent; ent = ent->next) {
+ if (ent != rule && strcmp(ent->pattern, rule->pattern) == 0)
+ found = 1;
+ }
+ if (!found) {
+ filter_rule *R_rule = new0(filter_rule);
+ R_rule->rflags = FILTRULE_INCLUDE + (saw_wild ? FILTRULE_WILD : 0);
+ R_rule->pattern = strdup(rule->pattern);
+ R_rule->u.slash_cnt = slash_cnt;
+ R_rule->next = implied_filter_list.head;
+ implied_filter_list.head = R_rule;
+ }
+ }
+ slash_cnt++;
+ *p++ = *cp++;
+ break;
+ default:
+ *p++ = *cp++;
+ break;
+ }
+ }
+ *p = '\0';
+ rule->u.slash_cnt = slash_cnt;
+ arg = (const char *)rule->pattern;
+ }
+
+ if (recurse || xfer_dirs) {
+ /* Now create a rule with an added "/" & "**" or "*" at the end */
+ rule = new0(filter_rule);
+ if (recurse)
+ rule->rflags = FILTRULE_INCLUDE | FILTRULE_WILD | FILTRULE_WILD2;
+ else
+ rule->rflags = FILTRULE_INCLUDE | FILTRULE_WILD;
+ /* A +4 in the len leaves enough room for / * * \0 or / * \0 \0 */
+ if (!saw_wild && backslash_cnt) {
+ /* We are appending a wildcard, so now the backslashes need to be escaped. */
+ p = rule->pattern = new_array(char, arg_len + backslash_cnt + 3 + 1);
+ cp = arg;
+ while (*cp) {
+ if (*cp == '\\')
+ *p++ = '\\';
+ *p++ = *cp++;
+ }
+ } else {
+ p = rule->pattern = new_array(char, arg_len + 3 + 1);
+ if (arg_len) {
+ memcpy(p, arg, arg_len);
+ p += arg_len;
+ }
+ }
+ if (p[-1] != '/')
+ *p++ = '/';
+ *p++ = '*';
+ if (recurse)
+ *p++ = '*';
+ *p = '\0';
+ rule->u.slash_cnt = slash_cnt + 1;
+ rule->next = implied_filter_list.head;
+ implied_filter_list.head = rule;
+ }
+}
+
/* This frees any non-inherited items, leaving just inherited items on the list. */
static void pop_filter_list(filter_rule_list *listp)
{
@@ -714,7 +860,7 @@ static void report_filter_result(enum lo
: name_flags & NAME_IS_DIR ? "directory"
: "file";
rprintf(code, "[%s] %sing %s %s because of pattern %s%s%s\n",
- w, actions[*w!='s'][!(ent->rflags & FILTRULE_INCLUDE)],
+ w, actions[*w=='g'][!(ent->rflags & FILTRULE_INCLUDE)],
t, name, ent->pattern,
ent->rflags & FILTRULE_DIRECTORY ? "/" : "", type);
}
@@ -886,6 +1032,7 @@ static filter_rule *parse_rule_tok(const
}
switch (ch) {
case ':':
+ trust_sender_filter = 1;
rule->rflags |= FILTRULE_PERDIR_MERGE
| FILTRULE_FINISH_SETUP;
/* FALL THROUGH */
Index: rsync-3.2.3/flist.c
===================================================================
--- rsync-3.2.3.orig/flist.c
+++ rsync-3.2.3/flist.c
@@ -72,6 +72,7 @@ extern int need_unsorted_flist;
extern int sender_symlink_iconv;
extern int output_needs_newline;
extern int sender_keeps_checksum;
+extern int trust_sender_filter;
extern int unsort_ndx;
extern uid_t our_uid;
extern struct stats stats;
@@ -82,8 +83,7 @@ extern char curr_dir[MAXPATHLEN];
extern struct chmod_mode_struct *chmod_modes;
-extern filter_rule_list filter_list;
-extern filter_rule_list daemon_filter_list;
+extern filter_rule_list filter_list, implied_filter_list, daemon_filter_list;
#ifdef ICONV_OPTION
extern int filesfrom_convert;
@@ -971,6 +971,19 @@ static struct file_struct *recv_file_ent
exit_cleanup(RERR_UNSUPPORTED);
}
+ if (*thisname != '.' || thisname[1] != '\0') {
+ int filt_flags = S_ISDIR(mode) ? NAME_IS_DIR : NAME_IS_FILE;
+ if (!trust_sender_filter /* a per-dir filter rule means we must trust the sender's filtering */
+ && filter_list.head && check_filter(&filter_list, FINFO, thisname, filt_flags) < 0) {
+ rprintf(FERROR, "ERROR: rejecting excluded file-list name: %s\n", thisname);
+ exit_cleanup(RERR_PROTOCOL);
+ }
+ if (implied_filter_list.head && check_filter(&implied_filter_list, FINFO, thisname, filt_flags) <= 0) {
+ rprintf(FERROR, "ERROR: rejecting unrequested file-list name: %s\n", thisname);
+ exit_cleanup(RERR_PROTOCOL);
+ }
+ }
+
if (inc_recurse && S_ISDIR(mode)) {
if (one_file_system) {
/* Room to save the dir's device for -x */
Index: rsync-3.2.3/io.c
===================================================================
--- rsync-3.2.3.orig/io.c
+++ rsync-3.2.3/io.c
@@ -414,6 +414,7 @@ static void forward_filesfrom_data(void)
while (s != eob) {
if (*s++ == '\0') {
ff_xb.len = s - sob - 1;
+ add_implied_include(sob);
if (iconvbufs(ic_send, &ff_xb, &iobuf.out, flags) < 0)
exit_cleanup(RERR_PROTOCOL); /* impossible? */
write_buf(iobuf.out_fd, s-1, 1); /* Send the '\0'. */
@@ -445,9 +446,12 @@ static void forward_filesfrom_data(void)
char *f = ff_xb.buf + ff_xb.pos;
char *t = ff_xb.buf;
char *eob = f + len;
+ char *cur = t;
/* Eliminate any multi-'\0' runs. */
while (f != eob) {
if (!(*t++ = *f++)) {
+ add_implied_include(cur);
+ cur = t;
while (f != eob && *f == '\0')
f++;
}
Index: rsync-3.2.3/main.c
===================================================================
--- rsync-3.2.3.orig/main.c
+++ rsync-3.2.3/main.c
@@ -87,6 +87,7 @@ extern BOOL shutting_down;
extern int backup_dir_len;
extern int basis_dir_cnt;
extern int default_af_hint;
+extern int trust_sender_filter;
extern struct stats stats;
extern char *stdout_format;
extern char *logfile_format;
@@ -102,7 +103,7 @@ extern char curr_dir[MAXPATHLEN];
extern char backup_dir_buf[MAXPATHLEN];
extern char *basis_dir[MAX_BASIS_DIRS+1];
extern struct file_list *first_flist;
-extern filter_rule_list daemon_filter_list;
+extern filter_rule_list daemon_filter_list, implied_filter_list;
uid_t our_uid;
gid_t our_gid;
@@ -642,6 +643,7 @@ static pid_t do_cmd(char *cmd, char *mac
#ifdef ICONV_CONST
setup_iconv();
#endif
+ trust_sender_filter = 1;
} else if (local_server) {
/* If the user didn't request --[no-]whole-file, force
* it on, but only if we're not batch processing. */
@@ -1516,6 +1518,8 @@ static int start_client(int argc, char *
char *dummy_host;
int dummy_port = rsync_port;
int i;
+ if (filesfrom_fd < 0)
+ add_implied_include(remote_argv[0]);
/* For remote source, any extra source args must have either
* the same hostname or an empty hostname. */
for (i = 1; i < remote_argc; i++) {
@@ -1539,6 +1543,7 @@ static int start_client(int argc, char *
if (!rsync_port && !*arg) /* Turn an empty arg into a dot dir. */
arg = ".";
remote_argv[i] = arg;
+ add_implied_include(arg);
}
}
Index: rsync-3.2.3/receiver.c
===================================================================
--- rsync-3.2.3.orig/receiver.c
+++ rsync-3.2.3/receiver.c
@@ -584,10 +584,13 @@ int recv_files(int f_in, int f_out, char
if (DEBUG_GTE(RECV, 1))
rprintf(FINFO, "recv_files(%s)\n", fname);
- if (daemon_filter_list.head && (*fname != '.' || fname[1] != '\0')
- && check_filter(&daemon_filter_list, FLOG, fname, 0) < 0) {
- rprintf(FERROR, "attempt to hack rsync failed.\n");
- exit_cleanup(RERR_PROTOCOL);
+ if (daemon_filter_list.head && (*fname != '.' || fname[1] != '\0')) {
+ int filt_flags = S_ISDIR(file->mode) ? NAME_IS_DIR : NAME_IS_FILE;
+ if (check_filter(&daemon_filter_list, FLOG, fname, filt_flags) < 0) {
+ rprintf(FERROR, "ERROR: rejecting file transfer request for daemon excluded file: %s\n",
+ fname);
+ exit_cleanup(RERR_PROTOCOL);
+ }
}
#ifdef SUPPORT_XATTRS
Index: rsync-3.2.3/rsync.1.md
===================================================================
--- rsync-3.2.3.orig/rsync.1.md
+++ rsync-3.2.3/rsync.1.md
@@ -304,6 +304,35 @@ separate the files into different rsync
`--delay-updates` (which doesn't affect the sorted transfer order, but does
make the final file-updating phase happen much more rapidly).
+## MULTI-HOST SECURITY
+
+Rsync takes steps to ensure that the file requests that are shared in a
+transfer are protected against various security issues. Most of the potential
+problems arise on the receiving side where rsync takes steps to ensure that the
+list of files being transferred remains within the bounds of what was
+requested.
+
+Toward this end, rsync 3.1.2 and later have aborted when a file list contains
+an absolute or relative path that tries to escape out of the top of the
+transfer. Also, beginning with version 3.2.5 (or a version patched against
+CVE-2022-29154), rsync does two more safety checks of the file list to (1)
+ensure that no extra source arguments were added into the transfer other than
+those that the client requested and (2) ensure that the file list obeys the
+exclude rules that we sent to the sender.
+
+For those that don't yet have a 3.2.5 (or a version patched against
+CVE-2022-29154) client rsync, it is safest to do a copy into a dedicated
+destination directory for the remote files rather than requesting the remote
+content get mixed in with other local content. For example, doing an rsync copy
+into your home directory is potentially unsafe on an older rsync if the remote
+rsync is being controlled by a bad actor:
+
+> rsync -aiv host1:dir1 ~
+
+A safer command would be:
+
+> rsync -aiv host1:dir1 ~/host1-files
+
# EXAMPLES
Here are some examples of how I use rsync.
@@ -3493,8 +3522,13 @@ available rule prefixes:
0. `exclude, '-'` specifies an exclude pattern.
0. `include, '+'` specifies an include pattern.
-0. `merge, '.'` specifies a merge-file to read for more rules.
-0. `dir-merge, ':'` specifies a per-directory merge-file.
+0. `merge, '.'` specifies a merge-file on the client side to read for more
+ rules.
+0. `dir-merge, ':'` specifies a per-directory merge-file. Using this kind of
+ filter rule requires that you trust the sending side's filter checking, and
+ thus it disables the receiver's verification of the file-list names against
+ the filter rules (since only the sender can know for sure if it obeyed all
+ the filter rules when some are per-dir merged from the sender's files).
0. `hide, 'H'` specifies a pattern for hiding files from the transfer.
0. `show, 'S'` files that match the pattern are not hidden.
0. `protect, 'P'` specifies a pattern for protecting files from deletion.
