[pacman-dev] [PATCH v3] Fallback to detached signatures during keyring check
Andrew Gregory
andrew.gregory.8 at gmail.com
Thu Jun 4 01:40:12 UTC 2020
On 06/01/20 at 11:45pm, Anatol Pomozov wrote:
> 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 | 34 ++++++++++++++++++++++++++++++++++
> lib/libalpm/sync.c | 18 +++++++++---------
> lib/libalpm/util.c | 37 +++++++++++++++++++++++++++++++++++++
> lib/libalpm/util.h | 1 +
> 5 files changed, 92 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.
alpm_errno_t values are positive.
> + */
> +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..1335b70e 100644
> --- a/lib/libalpm/package.c
> +++ b/lib/libalpm/package.c
> @@ -268,6 +268,40 @@ 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)
> +{
> + ASSERT(pkg != NULL, return -1);
> +
> + if(pkg->base64_sig) {
> + return alpm_decode_signature(pkg->base64_sig, sig, sig_len);
You're returning an error without setting pm_errno.
> + } else {
> + char *pkgpath, *sigpath;
> + alpm_errno_t err;
> + int ret = -1;
> +
> + 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)) {
> + GOTO_ERR(pkg->handle, ALPM_ERR_SIG_MISSING, exit);
> + }
> + 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, exit);
> + }
> + ret = 0;
> +exit:
Change exit to cleanup; exit makes it look like you are terminating
the program.
> + 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..65a6f3df 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 -1;
-1 is not an alpm_errno_t.
> + }
> +
> + 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
More information about the pacman-dev
mailing list