[pacman-dev] [PATCH v4] Fallback to detached signatures during keyring check
Anatol Pomozov
anatol.pomozov at gmail.com
Thu Jun 4 17:35:45 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 | 11 +++++++++++
lib/libalpm/package.c | 40 ++++++++++++++++++++++++++++++++++++++++
lib/libalpm/sync.c | 18 +++++++++---------
lib/libalpm/util.c | 37 +++++++++++++++++++++++++++++++++++++
lib/libalpm/util.h | 1 +
5 files changed, 98 insertions(+), 9 deletions(-)
diff --git a/lib/libalpm/alpm.h b/lib/libalpm/alpm.h
index c6a13273..0ba57109 100644
--- a/lib/libalpm/alpm.h
+++ b/lib/libalpm/alpm.h
@@ -1403,6 +1403,17 @@ 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
+ * a buffer needed for the signature data. Caller is responsible for
+ * freeing this buffer.
+ * @param sig_len output parameter for the signature data length.
+ * @return 0 on success, negative number on error.
+ */
+int alpm_pkg_get_sig(alpm_pkg_t *pkg, unsigned char **sig, size_t *sig_len);
+
/** 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..0885b27b 100644
--- a/lib/libalpm/package.c
+++ b/lib/libalpm/package.c
@@ -268,6 +268,46 @@ 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, size_t *sig_len)
+{
+ if(pkg != NULL) {
+ RET_ERR(pkg->handle, ALPM_ERR_WRONG_ARGS, -1);
+ }
+
+ if(pkg->base64_sig) {
+ int ret = alpm_decode_signature(pkg->base64_sig, sig, sig_len);
+ if(ret != 0) {
+ RET_ERR(pkg->handle, ALPM_ERR_SIG_INVALID, -1);
+ }
+ return 0;
+ } else {
+ char *pkgpath = NULL, *sigpath = NULL;
+ alpm_errno_t err;
+ int ret = -1;
+
+ pkgpath = _alpm_filecache_find(pkg->handle, pkg->filename);
+ if(!pkgpath) {
+ GOTO_ERR(pkg->handle, ALPM_ERR_PKG_NOT_FOUND, cleanup);
+ }
+ sigpath = _alpm_sigpath(pkg->handle, pkgpath);
+ if(!sigpath || _alpm_access(pkg->handle, NULL, sigpath, R_OK)) {
+ GOTO_ERR(pkg->handle, ALPM_ERR_SIG_MISSING, cleanup);
+ }
+ err = _alpm_read_file(sigpath, sig, sig_len);
+ if(err == ALPM_ERR_OK) {
+ _alpm_log(pkg->handle, ALPM_LOG_DEBUG, "found detached signature %s with size %ld\n",
+ sigpath, *sig_len);
+ } else {
+ GOTO_ERR(pkg->handle, err, cleanup);
+ }
+ ret = 0;
+cleanup:
+ FREE(pkgpath);
+ FREE(sigpath);
+ return ret;
+ }
+}
+
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..9350793a 100644
--- a/lib/libalpm/sync.c
+++ b/lib/libalpm/sync.c
@@ -880,18 +880,18 @@ 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 *sig = NULL;
+ size_t sig_len;
+ int ret = alpm_pkg_get_sig(pkg, &sig, &sig_len);
+ if(ret == 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, sig,
+ 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 +905,8 @@ static int check_keyring(alpm_handle_t *handle)
}
FREELIST(keys);
}
- free(decoded_sigdata);
}
+ free(sig);
}
}
diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c
index 76728eb4..b70a8192 100644
--- a/lib/libalpm/util.c
+++ b/lib/libalpm/util.c
@@ -1489,3 +1489,40 @@ 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
+ * @param data_len size of the output buffer
+ * @return error code for the operation
+ */
+alpm_errno_t _alpm_read_file(const char *filepath, unsigned char **data, size_t *data_len)
+{
+ struct stat st;
+ FILE *fp;
+
+ if((fp = fopen(filepath, "rb")) == NULL) {
+ return ALPM_ERR_NOT_A_FILE;
+ }
+
+ if(fstat(fileno(fp), &st) != 0) {
+ fclose(fp);
+ return ALPM_ERR_NOT_A_FILE;
+ }
+ *data_len = st.st_size;
+
+ MALLOC(*data, *data_len, fclose(fp); return ALPM_ERR_MEMORY);
+
+ if(fread(*data, *data_len, 1, fp) != 1) {
+ FREE(*data);
+ fclose(fp);
+ return ALPM_ERR_SYSTEM;
+ }
+
+ fclose(fp);
+ return ALPM_ERR_OK;
+}
diff --git a/lib/libalpm/util.h b/lib/libalpm/util.h
index 4fc6e718..03c8ed44 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);
+alpm_errno_t _alpm_read_file(const char *filepath, unsigned char **data, size_t *data_len);
#ifndef HAVE_STRSEP
char *strsep(char **, const char *);
--
2.27.0
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