[FFmpeg-devel] [PATCH 1/2] avcodec: add codec_whitelist

[Michael Niedermayer]

This allows restricting decoders to a list of needed ones for improved security

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
---
 libavcodec/avcodec.h       |    8 ++++++++
 libavcodec/options_table.h |    1 +
 libavcodec/utils.c         |    6 ++++++
 3 files changed, 15 insertions(+)

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 94e82f7..608de9c 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -3083,6 +3083,14 @@ typedef struct AVCodecContext {
      * - decoding: unused.
      */
     uint16_t *chroma_intra_matrix;
+
+    /**
+     * ',' seperated list of allowed decoders.
+     * If NULL then all are allowed
+     * - encoding: unused
+     * - decoding: set by user through AVOPtions (NO direct access)
+     */
+    char *codec_whitelist;
 } AVCodecContext;
 
 AVRational av_codec_get_pkt_timebase         (const AVCodecContext *avctx);
diff --git a/libavcodec/options_table.h b/libavcodec/options_table.h
index ad3d52e..ae217e5 100644
--- a/libavcodec/options_table.h
+++ b/libavcodec/options_table.h
@@ -468,6 +468,7 @@ static const AVOption avcodec_options[] = {
 {"bb", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AV_FIELD_BB }, 0, 0, V|D|E, "field_order" },
 {"tb", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AV_FIELD_TB }, 0, 0, V|D|E, "field_order" },
 {"bt", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AV_FIELD_BT }, 0, 0, V|D|E, "field_order" },
+{"codec_whitelist", "List of decoders that are allowed to be used", OFFSET(codec_whitelist), AV_OPT_TYPE_STRING, { .str = NULL },  CHAR_MIN, CHAR_MAX, D },
 {NULL},
 };
 
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 9eb2b5b..f715f27 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -1381,6 +1381,12 @@ int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *code
     if ((ret = av_opt_set_dict(avctx, &tmp)) < 0)
         goto free_and_end;
 
+    if (avctx->codec_whitelist && av_match_list(codec->name, avctx->codec_whitelist, ',') <= 0) {
+        av_log(avctx, AV_LOG_ERROR, "Codec not on whitelist\n");
+        ret = AVERROR(EINVAL);
+        goto free_and_end;
+    }
+
     // only call ff_set_dimensions() for non H.264/VP6F codecs so as not to overwrite previously setup dimensions
     if (!(avctx->coded_width && avctx->coded_height && avctx->width && avctx->height &&
           (avctx->codec_id == AV_CODEC_ID_H264 || avctx->codec_id == AV_CODEC_ID_VP6F))) {
-- 
1.7.9.5