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b38e97e03b
* gnu/packages/backup.scm (libarchive)[replacement]: New field. (libarchive/fixed): New variable. * gnu/packages/patches/libarchive-7zip-heap-overflow.patch, gnu/packages/patches/libarchive-fix-symlink-check.patch, gnu/packages/patches/libarchive-fix-filesystem-attacks.patch, gnu/packages/patches/libarchive-safe_fprintf-buffer-overflow.patch: New files. * gnu/local.mk (dist_patch_DATA): Add them.
445 lines
14 KiB
Diff
445 lines
14 KiB
Diff
This patch fixes two bugs that allow attackers to overwrite or change
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the permissions of arbitrary files:
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https://github.com/libarchive/libarchive/issues/745
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https://github.com/libarchive/libarchive/issues/746
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Patch copied from upstream repository:
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https://github.com/libarchive/libarchive/commit/dfd6b54ce33960e420fb206d8872fb759b577ad9
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From dfd6b54ce33960e420fb206d8872fb759b577ad9 Mon Sep 17 00:00:00 2001
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From: Tim Kientzle <kientzle@acm.org>
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Date: Sun, 11 Sep 2016 13:21:57 -0700
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Subject: [PATCH] Fixes for Issue #745 and Issue #746 from Doran Moppert.
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---
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libarchive/archive_write_disk_posix.c | 294 ++++++++++++++++++++++++++--------
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1 file changed, 227 insertions(+), 67 deletions(-)
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diff --git a/libarchive/archive_write_disk_posix.c b/libarchive/archive_write_disk_posix.c
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index 8f0421e..abe1a86 100644
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--- a/libarchive/archive_write_disk_posix.c
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+++ b/libarchive/archive_write_disk_posix.c
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@@ -326,12 +326,14 @@ struct archive_write_disk {
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#define HFS_BLOCKS(s) ((s) >> 12)
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+static int check_symlinks_fsobj(char *path, int *error_number, struct archive_string *error_string, int flags);
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static int check_symlinks(struct archive_write_disk *);
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static int create_filesystem_object(struct archive_write_disk *);
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static struct fixup_entry *current_fixup(struct archive_write_disk *, const char *pathname);
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#if defined(HAVE_FCHDIR) && defined(PATH_MAX)
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static void edit_deep_directories(struct archive_write_disk *ad);
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#endif
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+static int cleanup_pathname_fsobj(char *path, int *error_number, struct archive_string *error_string, int flags);
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static int cleanup_pathname(struct archive_write_disk *);
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static int create_dir(struct archive_write_disk *, char *);
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static int create_parent_dir(struct archive_write_disk *, char *);
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@@ -2014,6 +2016,10 @@ create_filesystem_object(struct archive_write_disk *a)
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const char *linkname;
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mode_t final_mode, mode;
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int r;
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+ /* these for check_symlinks_fsobj */
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+ char *linkname_copy; /* non-const copy of linkname */
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+ struct archive_string error_string;
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+ int error_number;
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/* We identify hard/symlinks according to the link names. */
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/* Since link(2) and symlink(2) don't handle modes, we're done here. */
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@@ -2022,6 +2028,27 @@ create_filesystem_object(struct archive_write_disk *a)
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#if !HAVE_LINK
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return (EPERM);
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#else
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+ archive_string_init(&error_string);
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+ linkname_copy = strdup(linkname);
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+ if (linkname_copy == NULL) {
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+ return (EPERM);
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+ }
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+ /* TODO: consider using the cleaned-up path as the link target? */
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+ r = cleanup_pathname_fsobj(linkname_copy, &error_number, &error_string, a->flags);
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+ if (r != ARCHIVE_OK) {
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+ archive_set_error(&a->archive, error_number, "%s", error_string.s);
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+ free(linkname_copy);
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+ /* EPERM is more appropriate than error_number for our callers */
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+ return (EPERM);
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+ }
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+ r = check_symlinks_fsobj(linkname_copy, &error_number, &error_string, a->flags);
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+ if (r != ARCHIVE_OK) {
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+ archive_set_error(&a->archive, error_number, "%s", error_string.s);
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+ free(linkname_copy);
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+ /* EPERM is more appropriate than error_number for our callers */
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+ return (EPERM);
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+ }
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+ free(linkname_copy);
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r = link(linkname, a->name) ? errno : 0;
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/*
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* New cpio and pax formats allow hardlink entries
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@@ -2362,115 +2389,228 @@ current_fixup(struct archive_write_disk *a, const char *pathname)
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* recent paths.
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*/
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/* TODO: Extend this to support symlinks on Windows Vista and later. */
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+
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+/*
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+ * Checks the given path to see if any elements along it are symlinks. Returns
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+ * ARCHIVE_OK if there are none, otherwise puts an error in errmsg.
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+ */
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static int
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-check_symlinks(struct archive_write_disk *a)
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+check_symlinks_fsobj(char *path, int *error_number, struct archive_string *error_string, int flags)
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{
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#if !defined(HAVE_LSTAT)
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/* Platform doesn't have lstat, so we can't look for symlinks. */
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(void)a; /* UNUSED */
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+ (void)path; /* UNUSED */
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+ (void)error_number; /* UNUSED */
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+ (void)error_string; /* UNUSED */
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+ (void)flags; /* UNUSED */
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return (ARCHIVE_OK);
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#else
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- char *pn;
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+ int res = ARCHIVE_OK;
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+ char *tail;
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+ char *head;
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+ int last;
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char c;
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int r;
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struct stat st;
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+ int restore_pwd;
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+
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+ /* Nothing to do here if name is empty */
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+ if(path[0] == '\0')
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+ return (ARCHIVE_OK);
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/*
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* Guard against symlink tricks. Reject any archive entry whose
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* destination would be altered by a symlink.
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+ *
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+ * Walk the filename in chunks separated by '/'. For each segment:
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+ * - if it doesn't exist, continue
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+ * - if it's symlink, abort or remove it
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+ * - if it's a directory and it's not the last chunk, cd into it
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+ * As we go:
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+ * head points to the current (relative) path
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+ * tail points to the temporary \0 terminating the segment we're currently examining
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+ * c holds what used to be in *tail
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+ * last is 1 if this is the last tail
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*/
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- /* Whatever we checked last time doesn't need to be re-checked. */
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- pn = a->name;
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- if (archive_strlen(&(a->path_safe)) > 0) {
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- char *p = a->path_safe.s;
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- while ((*pn != '\0') && (*p == *pn))
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- ++p, ++pn;
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- }
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+ restore_pwd = open(".", O_RDONLY | O_BINARY | O_CLOEXEC);
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+ __archive_ensure_cloexec_flag(restore_pwd);
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+ if (restore_pwd < 0)
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+ return (ARCHIVE_FATAL);
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+ head = path;
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+ tail = path;
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+ last = 0;
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+ /* TODO: reintroduce a safe cache here? */
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/* Skip the root directory if the path is absolute. */
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- if(pn == a->name && pn[0] == '/')
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- ++pn;
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- c = pn[0];
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- /* Keep going until we've checked the entire name. */
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- while (pn[0] != '\0' && (pn[0] != '/' || pn[1] != '\0')) {
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+ if(tail == path && tail[0] == '/')
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+ ++tail;
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+ /* Keep going until we've checked the entire name.
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+ * head, tail, path all alias the same string, which is
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+ * temporarily zeroed at tail, so be careful restoring the
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+ * stashed (c=tail[0]) for error messages.
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+ * Exiting the loop with break is okay; continue is not.
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+ */
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+ while (!last) {
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+ /* Skip the separator we just consumed, plus any adjacent ones */
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+ while (*tail == '/')
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+ ++tail;
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/* Skip the next path element. */
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- while (*pn != '\0' && *pn != '/')
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- ++pn;
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- c = pn[0];
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- pn[0] = '\0';
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+ while (*tail != '\0' && *tail != '/')
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+ ++tail;
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+ /* is this the last path component? */
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+ last = (tail[0] == '\0') || (tail[0] == '/' && tail[1] == '\0');
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+ /* temporarily truncate the string here */
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+ c = tail[0];
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+ tail[0] = '\0';
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/* Check that we haven't hit a symlink. */
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- r = lstat(a->name, &st);
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+ r = lstat(head, &st);
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if (r != 0) {
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+ tail[0] = c;
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/* We've hit a dir that doesn't exist; stop now. */
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if (errno == ENOENT) {
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break;
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} else {
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- /* Note: This effectively disables deep directory
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+ /* Treat any other error as fatal - best to be paranoid here
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+ * Note: This effectively disables deep directory
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* support when security checks are enabled.
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* Otherwise, very long pathnames that trigger
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* an error here could evade the sandbox.
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* TODO: We could do better, but it would probably
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* require merging the symlink checks with the
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* deep-directory editing. */
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- return (ARCHIVE_FAILED);
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+ if (error_number) *error_number = errno;
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+ if (error_string)
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+ archive_string_sprintf(error_string,
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+ "Could not stat %s",
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+ path);
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+ res = ARCHIVE_FAILED;
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+ break;
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+ }
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+ } else if (S_ISDIR(st.st_mode)) {
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+ if (!last) {
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+ if (chdir(head) != 0) {
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+ tail[0] = c;
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+ if (error_number) *error_number = errno;
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+ if (error_string)
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+ archive_string_sprintf(error_string,
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+ "Could not chdir %s",
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+ path);
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+ res = (ARCHIVE_FATAL);
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+ break;
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+ }
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+ /* Our view is now from inside this dir: */
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+ head = tail + 1;
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}
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} else if (S_ISLNK(st.st_mode)) {
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- if (c == '\0') {
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+ if (last) {
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/*
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* Last element is symlink; remove it
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* so we can overwrite it with the
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* item being extracted.
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*/
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- if (unlink(a->name)) {
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- archive_set_error(&a->archive, errno,
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- "Could not remove symlink %s",
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- a->name);
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- pn[0] = c;
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- return (ARCHIVE_FAILED);
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+ if (unlink(head)) {
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+ tail[0] = c;
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+ if (error_number) *error_number = errno;
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+ if (error_string)
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+ archive_string_sprintf(error_string,
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+ "Could not remove symlink %s",
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+ path);
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+ res = ARCHIVE_FAILED;
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+ break;
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}
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- a->pst = NULL;
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/*
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* Even if we did remove it, a warning
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* is in order. The warning is silly,
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* though, if we're just replacing one
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* symlink with another symlink.
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*/
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- if (!S_ISLNK(a->mode)) {
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- archive_set_error(&a->archive, 0,
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- "Removing symlink %s",
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- a->name);
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+ tail[0] = c;
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+ /* FIXME: not sure how important this is to restore
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+ if (!S_ISLNK(path)) {
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+ if (error_number) *error_number = 0;
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+ if (error_string)
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+ archive_string_sprintf(error_string,
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+ "Removing symlink %s",
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+ path);
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}
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+ */
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/* Symlink gone. No more problem! */
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- pn[0] = c;
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- return (0);
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- } else if (a->flags & ARCHIVE_EXTRACT_UNLINK) {
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+ res = ARCHIVE_OK;
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+ break;
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+ } else if (flags & ARCHIVE_EXTRACT_UNLINK) {
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/* User asked us to remove problems. */
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- if (unlink(a->name) != 0) {
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- archive_set_error(&a->archive, 0,
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- "Cannot remove intervening symlink %s",
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- a->name);
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- pn[0] = c;
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- return (ARCHIVE_FAILED);
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+ if (unlink(head) != 0) {
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+ tail[0] = c;
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+ if (error_number) *error_number = 0;
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+ if (error_string)
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+ archive_string_sprintf(error_string,
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+ "Cannot remove intervening symlink %s",
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+ path);
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+ res = ARCHIVE_FAILED;
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+ break;
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}
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- a->pst = NULL;
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+ tail[0] = c;
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} else {
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- archive_set_error(&a->archive, 0,
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- "Cannot extract through symlink %s",
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- a->name);
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- pn[0] = c;
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- return (ARCHIVE_FAILED);
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+ tail[0] = c;
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+ if (error_number) *error_number = 0;
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+ if (error_string)
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+ archive_string_sprintf(error_string,
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+ "Cannot extract through symlink %s",
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+ path);
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+ res = ARCHIVE_FAILED;
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+ break;
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}
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}
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- pn[0] = c;
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- if (pn[0] != '\0')
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- pn++; /* Advance to the next segment. */
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+ /* be sure to always maintain this */
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+ tail[0] = c;
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+ if (tail[0] != '\0')
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+ tail++; /* Advance to the next segment. */
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}
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- pn[0] = c;
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- /* We've checked and/or cleaned the whole path, so remember it. */
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- archive_strcpy(&a->path_safe, a->name);
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- return (ARCHIVE_OK);
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+ /* Catches loop exits via break */
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+ tail[0] = c;
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+#ifdef HAVE_FCHDIR
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+ /* If we changed directory above, restore it here. */
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+ if (restore_pwd >= 0) {
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+ r = fchdir(restore_pwd);
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+ if (r != 0) {
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+ if(error_number) *error_number = errno;
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+ if(error_string)
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+ archive_string_sprintf(error_string,
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+ "chdir() failure");
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+ }
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+ close(restore_pwd);
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+ restore_pwd = -1;
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+ if (r != 0) {
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+ res = (ARCHIVE_FATAL);
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+ }
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+ }
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+#endif
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+ /* TODO: reintroduce a safe cache here? */
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+ return res;
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#endif
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}
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+/*
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+ * Check a->name for symlinks, returning ARCHIVE_OK if its clean, otherwise
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+ * calls archive_set_error and returns ARCHIVE_{FATAL,FAILED}
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+ */
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+static int
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+check_symlinks(struct archive_write_disk *a)
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+{
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+ struct archive_string error_string;
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+ int error_number;
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+ int rc;
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+ archive_string_init(&error_string);
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+ rc = check_symlinks_fsobj(a->name, &error_number, &error_string, a->flags);
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+ if (rc != ARCHIVE_OK) {
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+ archive_set_error(&a->archive, error_number, "%s", error_string.s);
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+ }
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+ archive_string_free(&error_string);
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+ a->pst = NULL; /* to be safe */
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+ return rc;
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+}
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+
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+
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#if defined(__CYGWIN__)
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/*
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* 1. Convert a path separator from '\' to '/' .
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@@ -2544,15 +2684,17 @@ cleanup_pathname_win(struct archive_write_disk *a)
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* is set) if the path is absolute.
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*/
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static int
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-cleanup_pathname(struct archive_write_disk *a)
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+cleanup_pathname_fsobj(char *path, int *error_number, struct archive_string *error_string, int flags)
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{
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char *dest, *src;
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char separator = '\0';
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- dest = src = a->name;
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+ dest = src = path;
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if (*src == '\0') {
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- archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
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- "Invalid empty pathname");
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+ if (error_number) *error_number = ARCHIVE_ERRNO_MISC;
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+ if (error_string)
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+ archive_string_sprintf(error_string,
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+ "Invalid empty pathname");
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return (ARCHIVE_FAILED);
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}
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@@ -2561,9 +2703,11 @@ cleanup_pathname(struct archive_write_disk *a)
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#endif
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/* Skip leading '/'. */
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if (*src == '/') {
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- if (a->flags & ARCHIVE_EXTRACT_SECURE_NOABSOLUTEPATHS) {
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- archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
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- "Path is absolute");
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+ if (flags & ARCHIVE_EXTRACT_SECURE_NOABSOLUTEPATHS) {
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+ if (error_number) *error_number = ARCHIVE_ERRNO_MISC;
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+ if (error_string)
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+ archive_string_sprintf(error_string,
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+ "Path is absolute");
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return (ARCHIVE_FAILED);
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}
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@@ -2590,10 +2734,11 @@ cleanup_pathname(struct archive_write_disk *a)
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} else if (src[1] == '.') {
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if (src[2] == '/' || src[2] == '\0') {
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/* Conditionally warn about '..' */
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- if (a->flags & ARCHIVE_EXTRACT_SECURE_NODOTDOT) {
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- archive_set_error(&a->archive,
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- ARCHIVE_ERRNO_MISC,
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- "Path contains '..'");
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+ if (flags & ARCHIVE_EXTRACT_SECURE_NODOTDOT) {
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+ if (error_number) *error_number = ARCHIVE_ERRNO_MISC;
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+ if (error_string)
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+ archive_string_sprintf(error_string,
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+ "Path contains '..'");
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return (ARCHIVE_FAILED);
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}
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}
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@@ -2624,7 +2769,7 @@ cleanup_pathname(struct archive_write_disk *a)
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* We've just copied zero or more path elements, not including the
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* final '/'.
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*/
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- if (dest == a->name) {
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+ if (dest == path) {
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/*
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* Nothing got copied. The path must have been something
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* like '.' or '/' or './' or '/././././/./'.
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@@ -2639,6 +2784,21 @@ cleanup_pathname(struct archive_write_disk *a)
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return (ARCHIVE_OK);
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}
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+static int
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+cleanup_pathname(struct archive_write_disk *a)
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+{
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+ struct archive_string error_string;
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+ int error_number;
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+ int rc;
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+ archive_string_init(&error_string);
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+ rc = cleanup_pathname_fsobj(a->name, &error_number, &error_string, a->flags);
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+ if (rc != ARCHIVE_OK) {
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+ archive_set_error(&a->archive, error_number, "%s", error_string.s);
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+ }
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+ archive_string_free(&error_string);
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+ return rc;
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+}
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+
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/*
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* Create the parent directory of the specified path, assuming path
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* is already in mutable storage.
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