Brad Bishop | f8caae3 | 2019-03-25 13:13:56 -0400 | [diff] [blame^] | 1 | From 7cad044b72406cbadf048da432c29afea74c3c10 Mon Sep 17 00:00:00 2001 |
| 2 | From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl> |
| 3 | Date: Wed, 5 Dec 2018 22:45:02 +0100 |
| 4 | Subject: [PATCH] journald: set a limit on the number of fields |
| 5 | |
| 6 | The fix for CVE-2018-16865 is plucked from two commits that have |
| 7 | been pushed to systemd master. |
| 8 | |
| 9 | journald: set a limit on the number of fields (1k) |
| 10 | |
| 11 | We allocate a iovec entry for each field, so with many short entries, |
| 12 | our memory usage and processing time can be large, even with a relatively |
| 13 | small message size. Let's refuse overly long entries. |
| 14 | |
| 15 | CVE-2018-16865 |
| 16 | https://bugzilla.redhat.com/show_bug.cgi?id=1653861 |
| 17 | |
| 18 | What from I can see, the problem is not from an alloca, despite what the CVE |
| 19 | description says, but from the attack multiplication that comes from creating |
| 20 | many very small iovecs: (void* + size_t) for each three bytes of input message. |
| 21 | |
| 22 | Patch backported from systemd master at |
| 23 | 052c57f132f04a3cf4148f87561618da1a6908b4. |
| 24 | |
| 25 | journal-remote: set a limit on the number of fields in a message |
| 26 | |
| 27 | Existing use of E2BIG is replaced with ENOBUFS (entry too long), and E2BIG is |
| 28 | reused for the new error condition (too many fields). |
| 29 | |
| 30 | This matches the change done for systemd-journald, hence forming the second |
| 31 | part of the fix for CVE-2018-16865 |
| 32 | (https://bugzilla.redhat.com/show_bug.cgi?id=1653861). |
| 33 | |
| 34 | Patch backported from systemd master at |
| 35 | ef4d6abe7c7fab6cbff975b32e76b09feee56074. |
| 36 | with the changes applied by 7fdb237f5473cb8fc2129e57e8a0039526dcb4fd |
| 37 | removed. |
| 38 | |
| 39 | CVE: CVE-2018-16865 |
| 40 | Upstream-Status: Backport |
| 41 | Signed-off-by: Marcus Cooper <marcusc@axis.com> |
| 42 | --- |
| 43 | src/basic/journal-importer.c | 5 ++++- |
| 44 | src/basic/journal-importer.h | 3 +++ |
| 45 | src/journal-remote/journal-remote-main.c | 7 ++++++- |
| 46 | src/journal-remote/journal-remote.c | 5 ++++- |
| 47 | src/journal/journald-native.c | 5 +++++ |
| 48 | 5 files changed, 22 insertions(+), 3 deletions(-) |
| 49 | |
| 50 | diff --git a/src/basic/journal-importer.c b/src/basic/journal-importer.c |
| 51 | index ca203bbbfc..3ac55a66d9 100644 |
| 52 | --- a/src/basic/journal-importer.c |
| 53 | +++ b/src/basic/journal-importer.c |
| 54 | @@ -23,6 +23,9 @@ enum { |
| 55 | }; |
| 56 | |
| 57 | static int iovw_put(struct iovec_wrapper *iovw, void* data, size_t len) { |
| 58 | + if (iovw->count >= ENTRY_FIELD_COUNT_MAX) |
| 59 | + return -E2BIG; |
| 60 | + |
| 61 | if (!GREEDY_REALLOC(iovw->iovec, iovw->size_bytes, iovw->count + 1)) |
| 62 | return log_oom(); |
| 63 | |
| 64 | @@ -98,7 +101,7 @@ static int get_line(JournalImporter *imp, char **line, size_t *size) { |
| 65 | imp->scanned = imp->filled; |
| 66 | if (imp->scanned >= DATA_SIZE_MAX) { |
| 67 | log_error("Entry is bigger than %u bytes.", DATA_SIZE_MAX); |
| 68 | - return -E2BIG; |
| 69 | + return -ENOBUFS; |
| 70 | } |
| 71 | |
| 72 | if (imp->passive_fd) |
| 73 | diff --git a/src/basic/journal-importer.h b/src/basic/journal-importer.h |
| 74 | index f49ce734a1..c4ae45d32d 100644 |
| 75 | --- a/src/basic/journal-importer.h |
| 76 | +++ b/src/basic/journal-importer.h |
| 77 | @@ -16,6 +16,9 @@ |
| 78 | #define DATA_SIZE_MAX (1024*1024*768u) |
| 79 | #define LINE_CHUNK 8*1024u |
| 80 | |
| 81 | +/* The maximum number of fields in an entry */ |
| 82 | +#define ENTRY_FIELD_COUNT_MAX 1024 |
| 83 | + |
| 84 | struct iovec_wrapper { |
| 85 | struct iovec *iovec; |
| 86 | size_t size_bytes; |
| 87 | diff --git a/src/journal-remote/journal-remote-main.c b/src/journal-remote/journal-remote-main.c |
| 88 | index 8fda9d1499..3a01fef646 100644 |
| 89 | --- a/src/journal-remote/journal-remote-main.c |
| 90 | +++ b/src/journal-remote/journal-remote-main.c |
| 91 | @@ -212,7 +212,12 @@ static int process_http_upload( |
| 92 | break; |
| 93 | else if (r < 0) { |
| 94 | log_warning("Failed to process data for connection %p", connection); |
| 95 | - if (r == -E2BIG) |
| 96 | + if (r == -ENOBUFS) |
| 97 | + return mhd_respondf(connection, |
| 98 | + r, MHD_HTTP_PAYLOAD_TOO_LARGE, |
| 99 | + "Entry is above the maximum of %u, aborting connection %p.", |
| 100 | + DATA_SIZE_MAX, connection); |
| 101 | + else if (r == -E2BIG) |
| 102 | return mhd_respondf(connection, |
| 103 | r, MHD_HTTP_PAYLOAD_TOO_LARGE, |
| 104 | "Entry is too large, maximum is " STRINGIFY(DATA_SIZE_MAX) " bytes."); |
| 105 | diff --git a/src/journal-remote/journal-remote.c b/src/journal-remote/journal-remote.c |
| 106 | index beb75a1cb4..67e3a70c06 100644 |
| 107 | --- a/src/journal-remote/journal-remote.c |
| 108 | +++ b/src/journal-remote/journal-remote.c |
| 109 | @@ -408,7 +408,10 @@ int journal_remote_handle_raw_source( |
| 110 | log_debug("%zu active sources remaining", s->active); |
| 111 | return 0; |
| 112 | } else if (r == -E2BIG) { |
| 113 | - log_notice_errno(E2BIG, "Entry too big, skipped"); |
| 114 | + log_notice("Entry with too many fields, skipped"); |
| 115 | + return 1; |
| 116 | + } else if (r == -ENOBUFS) { |
| 117 | + log_notice("Entry too big, skipped"); |
| 118 | return 1; |
| 119 | } else if (r == -EAGAIN) { |
| 120 | return 0; |
| 121 | diff --git a/src/journal/journald-native.c b/src/journal/journald-native.c |
| 122 | index 5ff22a10af..951d092053 100644 |
| 123 | --- a/src/journal/journald-native.c |
| 124 | +++ b/src/journal/journald-native.c |
| 125 | @@ -140,6 +140,11 @@ static int server_process_entry( |
| 126 | } |
| 127 | |
| 128 | /* A property follows */ |
| 129 | + if (n > ENTRY_FIELD_COUNT_MAX) { |
| 130 | + log_debug("Received an entry that has more than " STRINGIFY(ENTRY_FIELD_COUNT_MAX) " fields, ignoring entry."); |
| 131 | + r = 1; |
| 132 | + goto finish; |
| 133 | + } |
| 134 | |
| 135 | /* n existing properties, 1 new, +1 for _TRANSPORT */ |
| 136 | if (!GREEDY_REALLOC(iovec, m, |
| 137 | -- |
| 138 | 2.11.0 |
| 139 | |