While integrating my encryption info changes, I noticed a problem with
the init info structs. I implemented them as side-data on the Stream.
But this means there can only be one per stream. However, there can
be multiple 'pssh' atoms in a single stream (e.g. for key rotation or
multiple key systems). (sorry for not noticing sooner)
Attached is a patch to fix this by making the init info a
singly-linked-list. It is ABI compatible and is still easy to use and
understand. The alternative would be to break ABI and have the
side-data methods return an array of pointers. I could do that
instead if that is preferable.
From bb941a77e882e93629d63d63059d0063b9519e29 Mon Sep 17 00:00:00 2001
From: Jacob Trimble <modma...@google.com>
Date: Mon, 23 Apr 2018 10:33:58 -0700
Subject: [PATCH] libavutil/encryption_info: Allow multiple init info.
It is possible for there to be multiple encryption init info structure.
For example, to support multiple key systems or in key rotation. This
changes the AVEncryptionInitInfo struct to be a linked list so there
can be multiple structs without breaking ABI.
Signed-off-by: Jacob Trimble <modma...@google.com>
---
libavutil/encryption_info.c | 154 +++++++++++++++++++++++-------------
libavutil/encryption_info.h | 5 ++
2 files changed, 106 insertions(+), 53 deletions(-)
diff --git a/libavutil/encryption_info.c b/libavutil/encryption_info.c
index 20a752d6b4..9935c10d74 100644
--- a/libavutil/encryption_info.c
+++ b/libavutil/encryption_info.c
@@ -160,13 +160,16 @@ uint8_t *av_encryption_info_add_side_data(const AVEncryptionInfo *info, size_t *
}
// The format of the AVEncryptionInitInfo side data:
-// u32be system_id_size
-// u32be num_key_ids
-// u32be key_id_size
-// u32be data_size
-// u8[system_id_size] system_id
-// u8[key_id_size][num_key_id] key_ids
-// u8[data_size] data
+// u32be init_info_count
+// {
+// u32be system_id_size
+// u32be num_key_ids
+// u32be key_id_size
+// u32be data_size
+// u8[system_id_size] system_id
+// u8[key_id_size][num_key_id] key_ids
+// u8[data_size] data
+// }[init_info_count]
#define FF_ENCRYPTION_INIT_INFO_EXTRA 16
@@ -215,6 +218,7 @@ void av_encryption_init_info_free(AVEncryptionInitInfo *info)
for (i = 0; i < info->num_key_ids; i++) {
av_free(info->key_ids[i]);
}
+ av_encryption_init_info_free(info->next);
av_free(info->system_id);
av_free(info->key_ids);
av_free(info->data);
@@ -225,71 +229,115 @@ void av_encryption_init_info_free(AVEncryptionInitInfo *info)
AVEncryptionInitInfo *av_encryption_init_info_get_side_data(
const uint8_t *side_data, size_t side_data_size)
{
- AVEncryptionInitInfo *info;
+ AVEncryptionInitInfo *ret = NULL, *info;
uint64_t system_id_size, num_key_ids, key_id_size, data_size, i;
+ uint64_t init_info_count;
- if (!side_data || side_data_size < FF_ENCRYPTION_INIT_INFO_EXTRA)
- return NULL;
-
- system_id_size = AV_RB32(side_data);
- num_key_ids = AV_RB32(side_data + 4);
- key_id_size = AV_RB32(side_data + 8);
- data_size = AV_RB32(side_data + 12);
-
- // UINT32_MAX + UINT32_MAX + UINT32_MAX * UINT32_MAX == UINT64_MAX
- if (side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA < system_id_size + data_size + num_key_ids * key_id_size)
- return NULL;
-
- info = av_encryption_init_info_alloc(system_id_size, num_key_ids, key_id_size, data_size);
- if (!info)
+ if (!side_data || side_data_size < 4)
return NULL;
- memcpy(info->system_id, side_data + 16, system_id_size);
- side_data += system_id_size + 16;
- for (i = 0; i < num_key_ids; i++) {
- memcpy(info->key_ids[i], side_data, key_id_size);
- side_data += key_id_size;
+ init_info_count = AV_RB32(side_data);
+ side_data += 4;
+ side_data_size -= 4;
+ for (i = 0; i < init_info_count; i++) {
+ if (side_data_size < FF_ENCRYPTION_INIT_INFO_EXTRA) {
+ av_encryption_init_info_free(ret);
+ return NULL;
+ }
+
+ system_id_size = AV_RB32(side_data);
+ num_key_ids = AV_RB32(side_data + 4);
+ key_id_size = AV_RB32(side_data + 8);
+ data_size = AV_RB32(side_data + 12);
+
+ // UINT32_MAX + UINT32_MAX + UINT32_MAX * UINT32_MAX == UINT64_MAX
+ if (side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA < system_id_size + data_size + num_key_ids * key_id_size) {
+ av_encryption_init_info_free(ret);
+ return NULL;
+ }
+ side_data += FF_ENCRYPTION_INIT_INFO_EXTRA;
+ side_data_size -= FF_ENCRYPTION_INIT_INFO_EXTRA;
+
+ info = av_encryption_init_info_alloc(system_id_size, num_key_ids, key_id_size, data_size);
+ if (!info) {
+ av_encryption_init_info_free(ret);
+ return NULL;
+ }
+ info->next = ret;
+ ret = info;
+
+ memcpy(info->system_id, side_data, system_id_size);
+ side_data += system_id_size;
+ side_data_size -= system_id_size;
+ for (i = 0; i < num_key_ids; i++) {
+ memcpy(info->key_ids[i], side_data, key_id_size);
+ side_data += key_id_size;
+ side_data_size -= key_id_size;
+ }
+ memcpy(info->data, side_data, data_size);
+ side_data += data_size;
+ side_data_size -= data_size;
}
- memcpy(info->data, side_data, data_size);
- return info;
+ return ret;
}
uint8_t *av_encryption_init_info_add_side_data(const AVEncryptionInitInfo *info, size_t *side_data_size)
{
+ const AVEncryptionInitInfo *cur_info, *cur_info_2;
uint8_t *buffer, *cur_buffer;
- uint32_t i, max_size;
-
- if (UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA < info->system_id_size ||
- UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA - info->system_id_size < info->data_size) {
- return NULL;
- }
-
- if (info->num_key_ids) {
- max_size = UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA - info->system_id_size - info->data_size;
- if (max_size / info->num_key_ids < info->key_id_size)
+ uint32_t i, init_info_count;
+
+ *side_data_size = 4;
+ init_info_count = 0;
+ for (cur_info = info; cur_info; cur_info = cur_info->next) {
+ // Detect a circular list.
+ for (cur_info_2 = info; cur_info_2 != cur_info; cur_info_2 = cur_info_2->next) {
+ if (cur_info->next == cur_info_2)
+ return NULL;
+ }
+ if (cur_info->next == cur_info)
+ return NULL;
+
+ if (UINT32_MAX == init_info_count ||
+ UINT32_MAX - *side_data_size < FF_ENCRYPTION_INIT_INFO_EXTRA ||
+ UINT32_MAX - *side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA < info->system_id_size ||
+ UINT32_MAX - *side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA - info->system_id_size < info->data_size) {
+ return NULL;
+ }
+ *side_data_size += FF_ENCRYPTION_INIT_INFO_EXTRA + info->system_id_size + info->data_size;
+ init_info_count++;
+
+ if (info->num_key_ids) {
+ if ((UINT32_MAX - *side_data_size) / info->num_key_ids < info->key_id_size) {
return NULL;
+ }
+ *side_data_size += info->num_key_ids * info->key_id_size;
+ }
}
- *side_data_size = FF_ENCRYPTION_INIT_INFO_EXTRA + info->system_id_size +
- info->data_size + (info->num_key_ids * info->key_id_size);
cur_buffer = buffer = av_malloc(*side_data_size);
if (!buffer)
return NULL;
- AV_WB32(cur_buffer, info->system_id_size);
- AV_WB32(cur_buffer + 4, info->num_key_ids);
- AV_WB32(cur_buffer + 8, info->key_id_size);
- AV_WB32(cur_buffer + 12, info->data_size);
- cur_buffer += 16;
-
- memcpy(cur_buffer, info->system_id, info->system_id_size);
- cur_buffer += info->system_id_size;
- for (i = 0; i < info->num_key_ids; i++) {
- memcpy(cur_buffer, info->key_ids[i], info->key_id_size);
- cur_buffer += info->key_id_size;
+ AV_WB32(cur_buffer, init_info_count);
+ cur_buffer += 4;
+ for (cur_info = info; cur_info; cur_info = cur_info->next) {
+ AV_WB32(cur_buffer, info->system_id_size);
+ AV_WB32(cur_buffer + 4, info->num_key_ids);
+ AV_WB32(cur_buffer + 8, info->key_id_size);
+ AV_WB32(cur_buffer + 12, info->data_size);
+ cur_buffer += 16;
+
+ memcpy(cur_buffer, info->system_id, info->system_id_size);
+ cur_buffer += info->system_id_size;
+ for (i = 0; i < info->num_key_ids; i++) {
+ memcpy(cur_buffer, info->key_ids[i], info->key_id_size);
+ cur_buffer += info->key_id_size;
+ }
+ memcpy(cur_buffer, info->data, info->data_size);
+ cur_buffer += info->data_size;
}
- memcpy(cur_buffer, info->data, info->data_size);
return buffer;
}
diff --git a/libavutil/encryption_info.h b/libavutil/encryption_info.h
index ec5501aac7..9140968fde 100644
--- a/libavutil/encryption_info.h
+++ b/libavutil/encryption_info.h
@@ -115,6 +115,11 @@ typedef struct AVEncryptionInitInfo {
*/
uint8_t* data;
uint32_t data_size;
+
+ /**
+ * An optional pointer to the next initialization info in the list.
+ */
+ struct AVEncryptionInitInfo *next;
} AVEncryptionInitInfo;
/**
--
2.17.0.484.g0c8726318c-goog
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
