diff options
| -rw-r--r-- | src/resolve/resolved-dns-packet.c | 22 | ||||
| -rw-r--r-- | src/resolve/resolved-dns-packet.h | 4 | ||||
| -rw-r--r-- | src/resolve/test-resolved-packet.c | 5 |
3 files changed, 21 insertions, 10 deletions
diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c index a486216d68..49a04615d4 100644 --- a/src/resolve/resolved-dns-packet.c +++ b/src/resolve/resolved-dns-packet.c @@ -29,7 +29,7 @@ #define EDNS0_OPT_DO (1<<15) #define DNS_PACKET_SIZE_START 512u -assert_cc(DNS_PACKET_SIZE_START > UDP_PACKET_HEADER_SIZE) +assert_cc(DNS_PACKET_SIZE_START > DNS_PACKET_HEADER_SIZE) typedef struct DnsPacketRewinder { DnsPacket *packet; @@ -44,20 +44,28 @@ static void rewind_dns_packet(DnsPacketRewinder *rewinder) { #define INIT_REWINDER(rewinder, p) do { rewinder.packet = p; rewinder.saved_rindex = p->rindex; } while (0) #define CANCEL_REWINDER(rewinder) do { rewinder.packet = NULL; } while (0) -int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t mtu) { +int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t min_alloc_dsize) { DnsPacket *p; size_t a; assert(ret); - /* When dns_packet_new() is called with mtu == 0, allocate more than the + /* The caller may not check what is going to be truly allocated, so do not allow to + * allocate a DNS packet bigger than DNS_PACKET_SIZE_MAX. + */ + if (min_alloc_dsize > DNS_PACKET_SIZE_MAX) { + log_error("Requested packet data size too big: %zu", min_alloc_dsize); + return -EFBIG; + } + + /* When dns_packet_new() is called with min_alloc_dsize == 0, allocate more than the * absolute minimum (which is the dns packet header size), to avoid * resizing immediately again after appending the first data to the packet. */ - if (mtu < UDP_PACKET_HEADER_SIZE) + if (min_alloc_dsize < DNS_PACKET_HEADER_SIZE) a = DNS_PACKET_SIZE_START; else - a = MAX(mtu, DNS_PACKET_HEADER_SIZE); + a = min_alloc_dsize; /* round up to next page size */ a = PAGE_ALIGN(ALIGN(sizeof(DnsPacket)) + a) - ALIGN(sizeof(DnsPacket)); @@ -131,13 +139,13 @@ void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool trun } } -int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu, bool dnssec_checking_disabled) { +int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t min_alloc_dsize, bool dnssec_checking_disabled) { DnsPacket *p; int r; assert(ret); - r = dns_packet_new(&p, protocol, mtu); + r = dns_packet_new(&p, protocol, min_alloc_dsize); if (r < 0) return r; diff --git a/src/resolve/resolved-dns-packet.h b/src/resolve/resolved-dns-packet.h index 5dff272fd9..a65d6d38cf 100644 --- a/src/resolve/resolved-dns-packet.h +++ b/src/resolve/resolved-dns-packet.h @@ -183,8 +183,8 @@ static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) { (unsigned) DNS_PACKET_ARCOUNT(p); } -int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t mtu); -int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu, bool dnssec_checking_disabled); +int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t min_alloc_dsize); +int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t min_alloc_dsize, bool dnssec_checking_disabled); void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool truncated); diff --git a/src/resolve/test-resolved-packet.c b/src/resolve/test-resolved-packet.c index 8b7da1408d..1b0041214b 100644 --- a/src/resolve/test-resolved-packet.c +++ b/src/resolve/test-resolved-packet.c @@ -22,8 +22,9 @@ static void test_dns_packet_new(void) { size_t i; + _cleanup_(dns_packet_unrefp) DnsPacket *p2 = NULL; - for (i = 0; i < DNS_PACKET_SIZE_MAX + 2; i++) { + for (i = 0; i <= DNS_PACKET_SIZE_MAX; i++) { _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; assert_se(dns_packet_new(&p, DNS_PROTOCOL_DNS, i) == 0); @@ -31,6 +32,8 @@ static void test_dns_packet_new(void) { log_debug("dns_packet_new: %zu → %zu", i, p->allocated); assert_se(p->allocated >= MIN(DNS_PACKET_SIZE_MAX, i)); } + + assert_se(dns_packet_new(&p2, DNS_PROTOCOL_DNS, DNS_PACKET_SIZE_MAX + 1) == -EFBIG); } int main(int argc, char **argv) { |