Comment match allocation in command_match() and nft_rule_to_iptables_command_state() were misaligned in that the latter set match_size to just what is required instead of what the match needs at maximum like the further. This led to failure when comparing them later and therefore a rule with a comment could not be deleted.
For comments of a specific length, the udata buffer is padded by libnftnl so nftnl_rule_get_data() returns a length value which is larger than the string (including NULL-byte). The trailing data is supposed to be ignored, but compare_matches() can't not know about that detail and therefore returns a false-negative if trailing data contains junk. To overcome this, use strncpy() when populating match data in nft_rule_to_iptables_command_state(). While being at it, make sure comment match allocation in that function is identical to what command_match() does with regards to data allocation size. Also use xtables_calloc() which does the required error checking. Signed-off-by: Phil Sutter <[email protected]> --- Changes since v1: - Use /bin/bash in testcase. Changes since v2: - Fix for odd comment lengths. --- iptables/nft-shared.c | 15 ++++++--------- .../testcases/nft-only/0003delete-with-comment_0 | 15 +++++++++++++++ 2 files changed, 21 insertions(+), 9 deletions(-) create mode 100755 iptables/tests/shell/testcases/nft-only/0003delete-with-comment_0 diff --git a/iptables/nft-shared.c b/iptables/nft-shared.c index 4557f17d43630..c8414294833c5 100644 --- a/iptables/nft-shared.c +++ b/iptables/nft-shared.c @@ -646,7 +646,7 @@ void nft_rule_to_iptables_command_state(const struct nftnl_rule *r, if (nftnl_rule_is_set(r, NFTNL_RULE_USERDATA)) { const void *data; - uint32_t len; + uint32_t len, size; struct xtables_match *match; struct xt_entry_match *m; @@ -656,15 +656,12 @@ void nft_rule_to_iptables_command_state(const struct nftnl_rule *r, if (match == NULL) return; - m = calloc(1, sizeof(struct xt_entry_match) + - sizeof(struct xt_comment_info)); - if (m == NULL) { - fprintf(stderr, "OOM"); - exit(EXIT_FAILURE); - } + size = XT_ALIGN(sizeof(struct xt_entry_match)) + match->size; + m = xtables_calloc(1, size); - memcpy(&m->data, get_comment(data, len), len); - m->u.match_size = len + XT_ALIGN(sizeof(struct xt_entry_match)); + strncpy((char *)m->data, get_comment(data, len), + match->size - 1); + m->u.match_size = size; m->u.user.revision = 0; strcpy(m->u.user.name, match->name); diff --git a/iptables/tests/shell/testcases/nft-only/0003delete-with-comment_0 b/iptables/tests/shell/testcases/nft-only/0003delete-with-comment_0 new file mode 100755 index 0000000000000..67af9fd897410 --- /dev/null +++ b/iptables/tests/shell/testcases/nft-only/0003delete-with-comment_0 @@ -0,0 +1,15 @@ +#!/bin/bash + +set -e + +[[ $XT_MULTI == */xtables-nft-multi ]] || { echo "skip $XT_MULTI"; exit 0; } + +comment1="foo bar" +comment2="xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" + +for ipt in iptables ip6tables; do + for comment in "$comment1" "$comment2"; do + $XT_MULTI $ipt -A INPUT -m comment --comment "$comment" -j ACCEPT + $XT_MULTI $ipt -D INPUT -m comment --comment "$comment" -j ACCEPT + done +done -- 2.18.0
