[pacman-dev] [PATCH] Fallback to detached signatures during keyring check
Anatol Pomozov
anatol.pomozov at gmail.com
Fri May 29 00:39:19 UTC 2020
Pacman has a 'key in keyring' verification step that makes sure the signatures
have a valid keyid. Currently pacman parses embedded package signatures only.
Add a fallback to detached signatures. If embedded signature is missing then it
tries to read corresponding *.sig file and get keyid from there.
Verification:
debug: found cached pkg: /var/cache/pacman/pkg/glib-networking-2.64.3-1-x86_64.pkg.tar.zst
debug: found detached signature /var/cache/pacman/pkg/glib-networking-2.64.3-1-x86_64.pkg.tar.zst.sig with size 310
debug: found signature key: A5E9288C4FA415FA
debug: looking up key A5E9288C4FA415FA locally
debug: key lookup success, key exists
Signed-off-by: Anatol Pomozov <anatol.pomozov at gmail.com>
---
lib/libalpm/alpm.h | 10 ++++++++++
lib/libalpm/package.c | 31 +++++++++++++++++++++++++++++++
lib/libalpm/sync.c | 17 ++++++++---------
lib/libalpm/util.c | 35 +++++++++++++++++++++++++++++++++++
lib/libalpm/util.h | 1 +
5 files changed, 85 insertions(+), 9 deletions(-)
diff --git a/lib/libalpm/alpm.h b/lib/libalpm/alpm.h
index c6a13273..9c5fff73 100644
--- a/lib/libalpm/alpm.h
+++ b/lib/libalpm/alpm.h
@@ -1403,6 +1403,16 @@ alpm_db_t *alpm_pkg_get_db(alpm_pkg_t *pkg);
*/
const char *alpm_pkg_get_base64_sig(alpm_pkg_t *pkg);
+/** Extracts package signature either from embedded package signature
+ * or if it is absent then reads data from detached signature file.
+ * @param pkg a pointer to package
+ * @param sig output parameter for signature data. Callee function allocates
+ * buffer needed for the signature data. Caller is responsible for
+ * freeing this buffer.
+ * @return size of a signature or negative number if error.
+ */
+int alpm_pkg_get_sig(alpm_pkg_t *pkg, unsigned char **sig);
+
/** Returns the method used to validate a package during install.
* @param pkg a pointer to package
* @return an enum member giving the validation method
diff --git a/lib/libalpm/package.c b/lib/libalpm/package.c
index 5c5fa073..e0e4d987 100644
--- a/lib/libalpm/package.c
+++ b/lib/libalpm/package.c
@@ -268,6 +268,37 @@ const char SYMEXPORT *alpm_pkg_get_base64_sig(alpm_pkg_t *pkg)
return pkg->base64_sig;
}
+int SYMEXPORT alpm_pkg_get_sig(alpm_pkg_t *pkg, unsigned char **sig)
+{
+ ASSERT(pkg != NULL, return -1);
+ pkg->handle->pm_errno = ALPM_ERR_OK;
+
+ if(pkg->base64_sig) {
+ size_t sig_len;
+ int ret = alpm_decode_signature(pkg->base64_sig, sig, &sig_len);
+ return ret == 0 ? (int)sig_len : -1;
+ } else {
+ char *pkgpath, *sigpath;
+ int len;
+
+ pkgpath = _alpm_filecache_find(pkg->handle, pkg->filename);
+ if(!pkgpath) {
+ RET_ERR(pkg->handle, ALPM_ERR_PKG_NOT_FOUND, -1);
+ }
+ sigpath = _alpm_sigpath(pkg->handle, pkgpath);
+ if(!sigpath || _alpm_access(pkg->handle, NULL, sigpath, R_OK)) {
+ FREE(pkgpath);
+ FREE(sigpath);
+ RET_ERR(pkg->handle, ALPM_ERR_SIG_MISSING, -1);
+ }
+ len = _alpm_read_file(sigpath, sig);
+ _alpm_log(pkg->handle, ALPM_LOG_DEBUG, "found detached signature %s with size %d\n", sigpath, len);
+ FREE(pkgpath);
+ FREE(sigpath);
+ return len;
+ }
+}
+
const char SYMEXPORT *alpm_pkg_get_arch(alpm_pkg_t *pkg)
{
ASSERT(pkg != NULL, return NULL);
diff --git a/lib/libalpm/sync.c b/lib/libalpm/sync.c
index 8c01ad95..f247b3aa 100644
--- a/lib/libalpm/sync.c
+++ b/lib/libalpm/sync.c
@@ -880,18 +880,17 @@ static int check_keyring(alpm_handle_t *handle)
}
level = alpm_db_get_siglevel(alpm_pkg_get_db(pkg));
- if((level & ALPM_SIG_PACKAGE) && pkg->base64_sig) {
- unsigned char *decoded_sigdata = NULL;
- size_t data_len;
- int decode_ret = alpm_decode_signature(pkg->base64_sig,
- &decoded_sigdata, &data_len);
- if(decode_ret == 0) {
+ if((level & ALPM_SIG_PACKAGE)) {
+ unsigned char *signature = NULL;
+ size_t sig_len = alpm_pkg_get_sig(pkg, &signature);
+ if(sig_len > 0) {
alpm_list_t *keys = NULL;
- if(alpm_extract_keyid(handle, pkg->name, decoded_sigdata,
- data_len, &keys) == 0) {
+ if(alpm_extract_keyid(handle, pkg->name, signature,
+ sig_len, &keys) == 0) {
alpm_list_t *k;
for(k = keys; k; k = k->next) {
char *key = k->data;
+ _alpm_log(handle, ALPM_LOG_DEBUG, "found signature key: %s\n", key);
if(!alpm_list_find(errors, key, key_cmp) &&
_alpm_key_in_keychain(handle, key) == 0) {
keyinfo = malloc(sizeof(struct keyinfo_t));
@@ -905,8 +904,8 @@ static int check_keyring(alpm_handle_t *handle)
}
FREELIST(keys);
}
- free(decoded_sigdata);
}
+ free(signature);
}
}
diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c
index 76728eb4..3d57817b 100644
--- a/lib/libalpm/util.c
+++ b/lib/libalpm/util.c
@@ -1489,3 +1489,38 @@ void _alpm_alloc_fail(size_t size)
{
fprintf(stderr, "alloc failure: could not allocate %zu bytes\n", size);
}
+
+/** This functions reads file content.
+ *
+ * Memory buffer is allocated by the callee function. It is responsibility
+ * of the caller to free the buffer
+ *
+ * @param filepath filepath to read
+ * @param data pointer to output buffer
+ * @return size of the data read or negative number in case of error
+ */
+int _alpm_read_file(const char *filepath, unsigned char **data)
+{
+ struct stat st;
+ FILE *fp;
+
+ if((fp = fopen(filepath, "rb")) == NULL) {
+ return -1;
+ }
+
+ if(fstat(fileno(fp), &st) != 0) {
+ fclose(fp);
+ return -1;
+ }
+
+ MALLOC(*data, st.st_size, fclose(fp); return -1);
+
+ if(fread(*data, st.st_size, 1, fp) != 1) {
+ FREE(*data);
+ fclose(fp);
+ return -1;
+ }
+
+ fclose(fp);
+ return st.st_size;
+}
diff --git a/lib/libalpm/util.h b/lib/libalpm/util.h
index 4fc6e718..50a94489 100644
--- a/lib/libalpm/util.h
+++ b/lib/libalpm/util.h
@@ -155,6 +155,7 @@ int _alpm_fnmatch_patterns(alpm_list_t *patterns, const char *string);
int _alpm_fnmatch(const void *pattern, const void *string);
void *_alpm_realloc(void **data, size_t *current, const size_t required);
void *_alpm_greedy_grow(void **data, size_t *current, const size_t required);
+int _alpm_read_file(const char *filepath, unsigned char **data);
#ifndef HAVE_STRSEP
char *strsep(char **, const char *);
--
2.26.2
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