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authorTimo Teräs <timo.teras@iki.fi>2018-09-05 19:49:22 +0300
committerTimo Teräs <timo.teras@iki.fi>2018-09-10 10:59:39 +0300
commit6484ed9849f03971eb48ee1fdc21a2f128247eb1 (patch)
treeed0ecf3a027f0497596355ae7895112c5cb99a4a
parentb11f9aa9286320a73a02cd14bfff5974e05a430b (diff)
downloadapk-tools-6484ed9849f03971eb48ee1fdc21a2f128247eb1.tar.bz2
rework unpacking of packages and harden package file format requirements
A crafted .apk file could to trick apk writing unverified data to an unexpected file during temporary file creation due to bugs in handling long link target name and the way a regular file is extracted. Several hardening steps are implemented to avoid this: - the temporary file is now always first unlinked (apk thus reserved all filenames .apk.* to be it's working files) - the temporary file is after that created with O_EXCL to avoid races - the temporary file is no longer directly the archive entry name and thus directly controlled by potentially untrusted data - long file names and link target names are now rejected - hard link targets are now more rigorously checked - various additional checks added for the extraction process to error out early in case of malformed (or old legacy) file Reported-by: Max Justicz <max@justi.cz>
-rw-r--r--src/apk_archive.h3
-rw-r--r--src/archive.c34
-rw-r--r--src/commit.c4
-rw-r--r--src/database.c160
-rw-r--r--src/gunzip.c35
-rw-r--r--src/package.c11
6 files changed, 142 insertions, 105 deletions
diff --git a/src/apk_archive.h b/src/apk_archive.h
index 6d1916d..7436dd3 100644
--- a/src/apk_archive.h
+++ b/src/apk_archive.h
@@ -28,7 +28,8 @@ int apk_tar_write_entry(struct apk_ostream *, const struct apk_file_info *ae,
int apk_tar_write_padding(struct apk_ostream *, const struct apk_file_info *ae);
int apk_archive_entry_extract(int atfd, const struct apk_file_info *ae,
- const char *suffix, struct apk_istream *is,
+ const char *extract_name, const char *hardlink_name,
+ struct apk_istream *is,
apk_progress_cb cb, void *cb_ctx);
#endif
diff --git a/src/archive.c b/src/archive.c
index bc36ce7..9a184fd 100644
--- a/src/archive.c
+++ b/src/archive.c
@@ -317,6 +317,12 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
break;
}
+ if (strnlen(entry.name, PATH_MAX) >= PATH_MAX-10 ||
+ (entry.link_target && strnlen(entry.link_target, PATH_MAX) >= PATH_MAX-10)) {
+ r = -ENAMETOOLONG;
+ goto err;
+ }
+
teis.bytes_left = entry.size;
if (entry.mode & S_IFMT) {
/* callback parser function */
@@ -428,23 +434,15 @@ int apk_tar_write_padding(struct apk_ostream *os, const struct apk_file_info *ae
}
int apk_archive_entry_extract(int atfd, const struct apk_file_info *ae,
- const char *suffix, struct apk_istream *is,
+ const char *extract_name, const char *link_target,
+ struct apk_istream *is,
apk_progress_cb cb, void *cb_ctx)
{
struct apk_xattr *xattr;
- char *fn = ae->name;
+ const char *fn = extract_name ?: ae->name;
int fd, r = -1, atflags = 0, ret = 0;
- if (suffix != NULL) {
- fn = alloca(PATH_MAX);
- snprintf(fn, PATH_MAX, "%s%s", ae->name, suffix);
- }
-
- if ((!S_ISDIR(ae->mode) && !S_ISREG(ae->mode)) ||
- (ae->link_target != NULL)) {
- /* non-standard entries need to be deleted first */
- unlinkat(atfd, fn, 0);
- }
+ if (unlinkat(atfd, fn, 0) != 0 && errno != ENOENT) return -errno;
switch (ae->mode & S_IFMT) {
case S_IFDIR:
@@ -454,7 +452,7 @@ int apk_archive_entry_extract(int atfd, const struct apk_file_info *ae,
break;
case S_IFREG:
if (ae->link_target == NULL) {
- int flags = O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC;
+ int flags = O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC | O_EXCL;
fd = openat(atfd, fn, flags, ae->mode & 07777);
if (fd < 0) {
@@ -465,18 +463,12 @@ int apk_archive_entry_extract(int atfd, const struct apk_file_info *ae,
if (r != ae->size) ret = r < 0 ? r : -ENOSPC;
close(fd);
} else {
- char *link_target = ae->link_target;
- if (suffix != NULL) {
- link_target = alloca(PATH_MAX);
- snprintf(link_target, PATH_MAX, "%s%s",
- ae->link_target, suffix);
- }
- r = linkat(atfd, link_target, atfd, fn, 0);
+ r = linkat(atfd, link_target ?: ae->link_target, atfd, fn, 0);
if (r < 0) ret = -errno;
}
break;
case S_IFLNK:
- r = symlinkat(ae->link_target, atfd, fn);
+ r = symlinkat(link_target ?: ae->link_target, atfd, fn);
if (r < 0) ret = -errno;
atflags |= AT_SYMLINK_NOFOLLOW;
break;
diff --git a/src/commit.c b/src/commit.c
index e82537f..ac6d7a5 100644
--- a/src/commit.c
+++ b/src/commit.c
@@ -232,8 +232,8 @@ static int run_commit_hook(void *ctx, int dirfd, const char *file)
struct apk_database *db = hook->db;
char fn[PATH_MAX], *argv[] = { fn, (char *) commit_hook_str[hook->type], NULL };
- if ((apk_flags & (APK_NO_SCRIPTS | APK_SIMULATE)) != 0)
- return 0;
+ if (file[0] == '.') return 0;
+ if ((apk_flags & (APK_NO_SCRIPTS | APK_SIMULATE)) != 0) return 0;
snprintf(fn, sizeof(fn), "etc/apk/commit_hooks.d" "/%s", file);
if ((apk_flags & APK_NO_COMMIT_HOOKS) != 0) {
diff --git a/src/database.c b/src/database.c
index eea7177..8cf63b2 100644
--- a/src/database.c
+++ b/src/database.c
@@ -828,8 +828,9 @@ int apk_db_index_read(struct apk_database *db, struct apk_bstream *bs, int repo)
case 'F':
if (diri) apk_db_dir_apply_diri_permissions(diri);
if (pkg->name == NULL) goto bad_entry;
- diri = apk_db_diri_new(db, pkg, l, &diri_node);
- file_diri_node = &diri->owned_files.first;
+ diri = find_diri(ipkg, l, NULL, &diri_node);
+ if (!diri) diri = apk_db_diri_new(db, pkg, l, &diri_node);
+ file_diri_node = hlist_tail_ptr(&diri->owned_files);
break;
case 'a':
if (file == NULL) goto bad_entry;
@@ -2358,6 +2359,31 @@ static struct apk_db_dir_instance *apk_db_install_directory_entry(struct install
return diri;
}
+#define TMPNAME_MAX (PATH_MAX + 64)
+
+static const char *format_tmpname(struct apk_package *pkg, struct apk_db_file *f, char tmpname[static TMPNAME_MAX])
+{
+ EVP_MD_CTX mdctx;
+ unsigned char md[EVP_MAX_MD_SIZE];
+ apk_blob_t b = APK_BLOB_PTR_LEN(tmpname, TMPNAME_MAX);
+
+ if (!f) return NULL;
+
+ EVP_DigestInit(&mdctx, EVP_sha256());
+ EVP_DigestUpdate(&mdctx, pkg->name->name, strlen(pkg->name->name) + 1);
+ EVP_DigestUpdate(&mdctx, f->diri->dir->name, f->diri->dir->namelen);
+ EVP_DigestUpdate(&mdctx, "/", 1);
+ EVP_DigestUpdate(&mdctx, f->name, f->namelen);
+ EVP_DigestFinal(&mdctx, md, NULL);
+
+ apk_blob_push_blob(&b, APK_BLOB_PTR_LEN(f->diri->dir->name, f->diri->dir->namelen));
+ apk_blob_push_blob(&b, APK_BLOB_STR("/.apk."));
+ apk_blob_push_hexdump(&b, APK_BLOB_PTR_LEN((char *)md, 24));
+ apk_blob_push_blob(&b, APK_BLOB_PTR_LEN("", 1));
+
+ return tmpname;
+}
+
static int apk_db_install_archive_entry(void *_ctx,
const struct apk_file_info *ae,
struct apk_istream *is)
@@ -2369,8 +2395,9 @@ static int apk_db_install_archive_entry(void *_ctx,
struct apk_installed_package *ipkg = pkg->ipkg;
apk_blob_t name = APK_BLOB_STR(ae->name), bdir, bfile;
struct apk_db_dir_instance *diri = ctx->diri;
- struct apk_db_file *file;
+ struct apk_db_file *file, *link_target_file = NULL;
int ret = 0, r, type = APK_SCRIPT_INVALID;
+ char tmpname_file[TMPNAME_MAX], tmpname_link_target[TMPNAME_MAX];
r = apk_sign_ctx_process_file(&ctx->sctx, ae, is);
if (r <= 0)
@@ -2437,6 +2464,40 @@ static int apk_db_install_archive_entry(void *_ctx,
diri = apk_db_install_directory_entry(ctx, bdir);
}
+ /* Check hard link target to exist in this package */
+ if (S_ISREG(ae->mode) && ae->link_target) {
+ do {
+ struct apk_db_file *lfile;
+ struct apk_db_dir_instance *ldiri;
+ struct hlist_node *n;
+ apk_blob_t hldir, hlfile;
+
+ if (!apk_blob_rsplit(APK_BLOB_STR(ae->link_target),
+ '/', &hldir, &hlfile))
+ break;
+
+ ldiri = find_diri(ipkg, hldir, diri, NULL);
+ if (ldiri == NULL)
+ break;
+
+ hlist_for_each_entry(lfile, n, &ldiri->owned_files,
+ diri_files_list) {
+ if (apk_blob_compare(APK_BLOB_PTR_LEN(lfile->name, lfile->namelen),
+ hlfile) == 0) {
+ link_target_file = lfile;
+ break;
+ }
+ }
+ } while (0);
+
+ if (!link_target_file) {
+ apk_error(PKG_VER_FMT": "BLOB_FMT": no hard link target (%s) in archive",
+ PKG_VER_PRINTF(pkg), BLOB_PRINTF(name), ae->link_target);
+ ipkg->broken_files = 1;
+ return 0;
+ }
+ }
+
opkg = NULL;
file = apk_db_file_query(db, bdir, bfile);
if (file != NULL) {
@@ -2495,41 +2556,21 @@ static int apk_db_install_archive_entry(void *_ctx,
if (apk_verbosity >= 3)
apk_message("%s", ae->name);
- /* Extract the file as name.apk-new */
+ /* Extract the file with temporary name */
file->acl = apk_db_acl_atomize(ae->mode, ae->uid, ae->gid, &ae->xattr_csum);
- r = apk_archive_entry_extract(db->root_fd, ae, ".apk-new", is,
- extract_cb, ctx);
+ r = apk_archive_entry_extract(
+ db->root_fd, ae,
+ format_tmpname(pkg, file, tmpname_file),
+ format_tmpname(pkg, link_target_file, tmpname_link_target),
+ is, extract_cb, ctx);
switch (r) {
case 0:
/* Hardlinks need special care for checksum */
- if (ae->csum.type == APK_CHECKSUM_NONE &&
- ae->link_target != NULL) {
- do {
- struct apk_db_file *lfile;
- struct apk_db_dir_instance *ldiri;
- struct hlist_node *n;
-
- if (!apk_blob_rsplit(APK_BLOB_STR(ae->link_target),
- '/', &bdir, &bfile))
- break;
-
- ldiri = find_diri(ipkg, bdir, diri, NULL);
- if (ldiri == NULL)
- break;
-
- hlist_for_each_entry(lfile, n, &ldiri->owned_files,
- diri_files_list) {
- if (apk_blob_compare(APK_BLOB_PTR_LEN(lfile->name, lfile->namelen),
- bfile) == 0) {
- memcpy(&file->csum, &lfile->csum,
- sizeof(file->csum));
- break;
- }
- }
- } while (0);
- } else
- memcpy(&file->csum, &ae->csum, sizeof(file->csum));
+ if (link_target_file)
+ memcpy(&file->csum, &link_target_file->csum, sizeof file->csum);
+ else
+ memcpy(&file->csum, &ae->csum, sizeof file->csum);
break;
case -ENOTSUP:
ipkg->broken_xattr = 1;
@@ -2547,8 +2588,11 @@ static int apk_db_install_archive_entry(void *_ctx,
if (name.ptr[name.len-1] == '/')
name.len--;
- diri = apk_db_install_directory_entry(ctx, name);
- apk_db_dir_prepare(db, diri->dir, ae->mode);
+ diri = ctx->diri = find_diri(ipkg, name, NULL, &ctx->file_diri_node);
+ if (!diri) {
+ diri = apk_db_install_directory_entry(ctx, name);
+ apk_db_dir_prepare(db, diri->dir, ae->mode);
+ }
apk_db_diri_set(diri, apk_db_acl_atomize(ae->mode, ae->uid, ae->gid, &ae->xattr_csum));
}
ctx->installed_size += ctx->current_file_size;
@@ -2558,7 +2602,7 @@ static int apk_db_install_archive_entry(void *_ctx,
static void apk_db_purge_pkg(struct apk_database *db,
struct apk_installed_package *ipkg,
- const char *exten)
+ int is_installed)
{
struct apk_db_dir_instance *diri;
struct apk_db_file *file;
@@ -2566,17 +2610,16 @@ static void apk_db_purge_pkg(struct apk_database *db,
struct apk_file_info fi;
struct hlist_node *dc, *dn, *fc, *fn;
unsigned long hash;
- char name[PATH_MAX];
+ char name[TMPNAME_MAX];
hlist_for_each_entry_safe(diri, dc, dn, &ipkg->owned_dirs, pkg_dirs_list) {
- if (exten == NULL)
- diri->dir->modified = 1;
+ if (is_installed) diri->dir->modified = 1;
hlist_for_each_entry_safe(file, fc, fn, &diri->owned_files, diri_files_list) {
- snprintf(name, sizeof(name),
- DIR_FILE_FMT "%s",
- DIR_FILE_PRINTF(diri->dir, file),
- exten ?: "");
+ if (is_installed)
+ snprintf(name, sizeof name, DIR_FILE_FMT, DIR_FILE_PRINTF(diri->dir, file));
+ else
+ format_tmpname(ipkg->pkg, file, name);
key = (struct apk_db_file_hash_key) {
.dirname = APK_BLOB_PTR_LEN(diri->dir->name, diri->dir->namelen),
@@ -2592,7 +2635,7 @@ static void apk_db_purge_pkg(struct apk_database *db,
if (apk_verbosity >= 3)
apk_message("%s", name);
__hlist_del(fc, &diri->owned_files.first);
- if (exten == NULL) {
+ if (is_installed) {
apk_hash_delete_hashed(&db->installed.files, APK_BLOB_BUF(&key), hash);
db->installed.stats.files--;
}
@@ -2613,7 +2656,7 @@ static void apk_db_migrate_files(struct apk_database *db,
struct apk_file_info fi;
struct hlist_node *dc, *dn, *fc, *fn;
unsigned long hash;
- char name[PATH_MAX], tmpname[PATH_MAX];
+ char name[PATH_MAX], tmpname[TMPNAME_MAX];
int cstype, r;
hlist_for_each_entry_safe(diri, dc, dn, &ipkg->owned_dirs, pkg_dirs_list) {
@@ -2621,10 +2664,8 @@ static void apk_db_migrate_files(struct apk_database *db,
dir->modified = 1;
hlist_for_each_entry_safe(file, fc, fn, &diri->owned_files, diri_files_list) {
- snprintf(name, sizeof(name), DIR_FILE_FMT,
- DIR_FILE_PRINTF(diri->dir, file));
- snprintf(tmpname, sizeof(tmpname), DIR_FILE_FMT ".apk-new",
- DIR_FILE_PRINTF(diri->dir, file));
+ snprintf(name, sizeof(name), DIR_FILE_FMT, DIR_FILE_PRINTF(diri->dir, file));
+ format_tmpname(ipkg->pkg, file, tmpname);
key = (struct apk_db_file_hash_key) {
.dirname = APK_BLOB_PTR_LEN(dir->name, dir->namelen),
@@ -2665,8 +2706,21 @@ static void apk_db_migrate_files(struct apk_database *db,
APK_FI_NOFOLLOW | file->csum.type, &fi);
if ((apk_flags & APK_CLEAN_PROTECTED) ||
(file->csum.type != APK_CHECKSUM_NONE &&
- apk_checksum_compare(&file->csum, &fi.csum) == 0))
+ apk_checksum_compare(&file->csum, &fi.csum) == 0)) {
unlinkat(db->root_fd, tmpname, 0);
+ } else {
+ snprintf(name, sizeof name,
+ DIR_FILE_FMT ".apk-new",
+ DIR_FILE_PRINTF(diri->dir, file));
+ if (renameat(db->root_fd, tmpname,
+ db->root_fd, name) != 0) {
+ apk_error(PKG_VER_FMT": failed to rename %s to %s.",
+ PKG_VER_PRINTF(ipkg->pkg),
+ tmpname, name);
+ ipkg->broken_files = 1;
+ }
+ }
+
} else {
/* Overwrite the old file */
if (renameat(db->root_fd, tmpname,
@@ -2799,7 +2853,7 @@ int apk_db_install_pkg(struct apk_database *db, struct apk_package *oldpkg,
if (ipkg == NULL)
goto ret_r;
apk_ipkg_run_script(ipkg, db, APK_SCRIPT_PRE_DEINSTALL, script_args);
- apk_db_purge_pkg(db, ipkg, NULL);
+ apk_db_purge_pkg(db, ipkg, TRUE);
apk_ipkg_run_script(ipkg, db, APK_SCRIPT_POST_DEINSTALL, script_args);
apk_pkg_uninstall(db, oldpkg);
goto ret_r;
@@ -2822,7 +2876,7 @@ int apk_db_install_pkg(struct apk_database *db, struct apk_package *oldpkg,
cb, cb_ctx, script_args);
if (r != 0) {
if (oldpkg != newpkg)
- apk_db_purge_pkg(db, ipkg, ".apk-new");
+ apk_db_purge_pkg(db, ipkg, FALSE);
apk_pkg_uninstall(db, newpkg);
goto ret_r;
}
@@ -2830,7 +2884,7 @@ int apk_db_install_pkg(struct apk_database *db, struct apk_package *oldpkg,
}
if (oldpkg != NULL && oldpkg != newpkg && oldpkg->ipkg != NULL) {
- apk_db_purge_pkg(db, oldpkg->ipkg, NULL);
+ apk_db_purge_pkg(db, oldpkg->ipkg, TRUE);
apk_pkg_uninstall(db, oldpkg);
}
diff --git a/src/gunzip.c b/src/gunzip.c
index 4fac9fa..2de841b 100644
--- a/src/gunzip.c
+++ b/src/gunzip.c
@@ -37,6 +37,16 @@ static void gzi_get_meta(void *stream, struct apk_file_meta *meta)
apk_bstream_get_meta(gis->bs, meta);
}
+static int gzi_boundary_change(struct apk_gzip_istream *gis)
+{
+ int r;
+
+ r = gis->cb(gis->cbctx, gis->err ? APK_MPART_END : APK_MPART_BOUNDARY, gis->cbarg);
+ if (r > 0) r = -ECANCELED;
+ if (r != 0) gis->err = r;
+ return r;
+}
+
static ssize_t gzi_read(void *stream, void *ptr, size_t size)
{
struct apk_gzip_istream *gis =
@@ -57,15 +67,8 @@ static ssize_t gzi_read(void *stream, void *ptr, size_t size)
while (gis->zs.avail_out != 0 && gis->err == 0) {
if (!APK_BLOB_IS_NULL(gis->cbarg)) {
- r = gis->cb(gis->cbctx,
- gis->err ? APK_MPART_END : APK_MPART_BOUNDARY,
- gis->cbarg);
- if (r > 0)
- r = -ECANCELED;
- if (r != 0) {
- gis->err = r;
+ if (gzi_boundary_change(gis))
goto ret;
- }
gis->cbarg = APK_BLOB_NULL;
}
if (gis->zs.avail_in == 0) {
@@ -86,14 +89,8 @@ static ssize_t gzi_read(void *stream, void *ptr, size_t size)
goto ret;
} else if (gis->zs.avail_in == 0) {
gis->err = 1;
- if (gis->cb != NULL) {
- r = gis->cb(gis->cbctx, APK_MPART_END,
- APK_BLOB_NULL);
- if (r > 0)
- r = -ECANCELED;
- if (r != 0)
- gis->err = r;
- }
+ gis->cbarg = APK_BLOB_NULL;
+ gzi_boundary_change(gis);
goto ret;
}
}
@@ -115,11 +112,7 @@ static ssize_t gzi_read(void *stream, void *ptr, size_t size)
* For boundaries it should be postponed to not
* be called until next gzip read is started. */
if (gis->err) {
- r = gis->cb(gis->cbctx,
- gis->err ? APK_MPART_END : APK_MPART_BOUNDARY,
- gis->cbarg);
- if (r > 0)
- r = -ECANCELED;
+ gzi_boundary_change(gis);
goto ret;
}
inflateEnd(&gis->zs);
diff --git a/src/package.c b/src/package.c
index 3be8b84..e19250a 100644
--- a/src/package.c
+++ b/src/package.c
@@ -476,13 +476,7 @@ void apk_sign_ctx_init(struct apk_sign_ctx *ctx, int action,
ctx->md = EVP_md_null();
break;
case APK_SIGN_VERIFY_IDENTITY:
- if (identity->type == APK_CHECKSUM_MD5) {
- ctx->md = EVP_md5();
- ctx->control_started = 1;
- ctx->data_started = 1;
- } else {
- ctx->md = EVP_sha1();
- }
+ ctx->md = EVP_sha1();
memcpy(&ctx->identity, identity, sizeof(ctx->identity));
break;
case APK_SIGN_GENERATE:
@@ -552,6 +546,9 @@ int apk_sign_ctx_process_file(struct apk_sign_ctx *ctx,
* style .PKGINFO */
if (ctx->has_data_checksum)
return -ENOMSG;
+ /* Error out early if identity part is missing */
+ if (ctx->action == APK_SIGN_VERIFY_IDENTITY)
+ return -EKEYREJECTED;
ctx->data_started = 1;
ctx->control_started = 1;
r = check_signing_key_trust(ctx);