Control: tags -1 confirmed moreinfo On 2021-07-14 21:48:50, Oxan van Leeuwen wrote: > Package: release.debian.org > Severity: normal > User: [email protected] > Usertags: unblock > > Please unblock package postsrsd > > [ Reason ] > Security fix for CVE-2021-35525. > > [ Impact ] > Package is vulnerable to a potential DoS attack. > > [ Tests ] > Tests from upstream backported, testsuite from upstream passes, manually > tested > functionality. > > [ Risks ] > Fix is a one-to-one backport from upstream, modulus formatting changes. > > [ Checklist ] > [x] all changes are documented in the d/changelog > [x] I reviewed all changes and I approve them > [x] attach debdiff against the package in testing > > [ Other info ] > N/A > > unblock postsrsd/1.10-2
If this is a pre-approval request, please go ahead and remove the moreinfo tag once the new version is available in unstable. Cheers > diff -Nru postsrsd-1.10/debian/changelog postsrsd-1.10/debian/changelog > --- postsrsd-1.10/debian/changelog 2020-12-02 22:36:36.000000000 +0100 > +++ postsrsd-1.10/debian/changelog 2021-07-14 21:21:11.000000000 +0200 > @@ -1,4 +1,12 @@ > -postsrsd (1.10-1) UNRELEASED; urgency=medium > +postsrsd (1.10-2) UNRELEASED; urgency=medium > + > + * Fix CVE-2021-35525: potential DoS when Postfix sends certain long data > + fields such as multiple concatenated email addresses. Fix backported from > + upstream commit 077be98d8c8. (Closes: #990439) > + > + -- Oxan van Leeuwen <[email protected]> Wed, 14 Jul 2021 21:21:11 > +0200 > + > +postsrsd (1.10-1) unstable; urgency=medium > > * New upstream release (Closes: #975633) > * Drop patches integrated upstream > diff -Nru > postsrsd-1.10/debian/patches/0002-SECURITY-Fix-DoS-on-overly-long-input-from-Postfix.patch > > postsrsd-1.10/debian/patches/0002-SECURITY-Fix-DoS-on-overly-long-input-from-Postfix.patch > --- > postsrsd-1.10/debian/patches/0002-SECURITY-Fix-DoS-on-overly-long-input-from-Postfix.patch > 1970-01-01 01:00:00.000000000 +0100 > +++ > postsrsd-1.10/debian/patches/0002-SECURITY-Fix-DoS-on-overly-long-input-from-Postfix.patch > 2021-07-14 21:21:11.000000000 +0200 > @@ -0,0 +1,211 @@ > +From: =?utf-8?q?Timo_R=C3=B6hling?= <[email protected]> > +Date: Sun, 21 Mar 2021 15:27:55 +0100 > +Subject: SECURITY: Fix DoS on overly long input from Postfix > +MIME-Version: 1.0 > +Content-Type: text/plain; charset="utf-8" > +Content-Transfer-Encoding: 8bit > + > +Thanks to Mateusz Jończyk who reported this issue and gave valuable > +feedback for its resolution. > + > +PostSRSd would hang on an overly long GET request, because the > +fread()/fwrite() logic in the subprocess would get confused by the > +remaining input line in its buffer. > + > +Theoretically, this error should never occur, as Postfix is supposed to > +send valid email addresses only, which are shorter than the buffer, even > +assuming every single character is percent-encoded. However, Postfix > +sometimes does seem to send malformed request with multiple concatenated > +email addresses. I'm not sure if there's a reliable way to trigger this > +condition by an external attacker, but it is a security bug in PostSRSd > +nevertheless. > + > +Fixes CVE-2021-35525. > + > +Origin: > https://github.com/roehling/postsrsd/commit/077be98d8c8a9847e4ae0c7dc09e7474cbe27db2 > +Forwarded: not-needed > +Last-Update: 2021-07-14 > +--- > + postsrsd.c | 52 > ++++++++++++++++++++++++++++++------------------- > + run_postsrsd_tests.bats | 40 +++++++++++++++++++++++++++++++++---- > + 2 files changed, 68 insertions(+), 24 deletions(-) > + > +diff --git a/postsrsd.c b/postsrsd.c > +index c009d8f..5ebf7f6 100644 > +--- a/postsrsd.c > ++++ b/postsrsd.c > +@@ -518,9 +518,9 @@ int main (int argc, char **argv) > + fds[sc].events = POLLIN; > + } > + while(TRUE) { > + int conn; > +- FILE *fp; > ++ FILE *fp_read, *fp_write; > + char linebuf[1024], *line; > + char keybuf[1024], *key; > + > + if (poll(fds, socket_count, 1000) < 0) { > +@@ -540,41 +540,53 @@ int main (int argc, char **argv) > + int i; > + // close listen sockets so that we don't stop the main daemon > process from restarting > + for (i = 0; i < socket_count; ++i) close (sockets[i]); > + > +- fp = fdopen(conn, "r+"); > +- if (fp == NULL) exit(EXIT_FAILURE); > +- fds[0].fd = conn; > +- fds[0].events = POLLIN; > +- if (poll(fds, 1, timeout * 1000) <= 0) return EXIT_FAILURE; > +- line = fgets(linebuf, sizeof(linebuf), fp); > +- while (line) { > +- fseek (fp, 0, SEEK_CUR); /* Workaround for Solaris */ > ++ /* create separate input/output streams */ > ++ fp_read = fdopen(conn, "r"); > ++ if (fp_read == NULL) > ++ return EXIT_FAILURE; > ++ fp_write = fdopen(dup(conn), "w"); > ++ if (fp_write == NULL) return EXIT_FAILURE; > ++ errno = 0; > ++ alarm(timeout); > ++ if (errno != 0) > ++ return EXIT_FAILURE; > ++ while ((line = fgets(linebuf, sizeof(linebuf), fp_read))) { > + char* token; > ++ alarm(0); > ++ if (strlen(line) >= sizeof(linebuf) - 1) { > ++ fprintf(fp_write, "500 Invalid request\n"); > ++ fflush(fp_write); > ++ return EXIT_FAILURE; > ++ } > + token = strtok(line, " \r\n"); > + if (token == NULL || strcmp(token, "get") != 0) { > +- fprintf (fp, "500 Invalid request\n"); > +- fflush (fp); > ++ fprintf (fp_write, "500 Invalid request\n"); > ++ fflush (fp_write); > + return EXIT_FAILURE; > + } > + token = strtok(NULL, "\r\n"); > + if (!token) { > +- fprintf (fp, "500 Invalid request\n"); > +- fflush (fp); > ++ fprintf (fp_write, "500 Invalid request\n"); > ++ fflush (fp_write); > + return EXIT_FAILURE; > + } > + key = url_decode(keybuf, sizeof(keybuf), token); > + if (!key) { > +- fprintf (fp, "500 Invalid request\n"); > +- fflush(fp); > ++ fprintf (fp_write, "500 Invalid request\n"); > ++ fflush(fp_write); > + return EXIT_FAILURE; > + } > +- handler[sc](srs, fp, key, domain, excludes); > +- fflush (fp); > +- if (poll(fds, 1, timeout * 1000) <= 0) break; > +- line = fgets(linebuf, sizeof(linebuf), fp); > ++ handler[sc](srs, fp_write, key, domain, excludes); > ++ fflush (fp_write); > ++ errno = 0; > ++ alarm(timeout); > ++ if (errno != 0) > ++ return EXIT_FAILURE; > + } > +- fclose (fp); > ++ fclose (fp_write); > ++ fclose (fp_read); > + return EXIT_SUCCESS; > + } > + close (conn); > + } > +diff --git a/run_postsrsd_tests.bats b/run_postsrsd_tests.bats > +index f4b04bb..3d52a50 100755 > +--- a/run_postsrsd_tests.bats > ++++ b/run_postsrsd_tests.bats > +@@ -2,9 +2,9 @@ > + # vim: filetype=bash: > + > + if [ ! -x "$POSTSRSD" ] > + then > +- for builddir in . build* obj* > ++ for builddir in . build* obj* _build* > + do > + if [ -x "${builddir}/postsrsd" ] > + then > + POSTSRSD="${builddir}/postsrsd" > +@@ -14,9 +14,9 @@ then > + fi > + if [ ! -x "$POSTSRSD" ] > + then > + cat>&2 <<- EOF > +- cannot find postsrsd executable (looked in ., build*, obj*) > ++ cannot find postsrsd executable (looked in ., build*, obj*, _build*) > + please build the executable first, or set the POSTSRSD > + environment variable if it is in a different location. > + > + EOF > +@@ -25,14 +25,21 @@ fi > + > + LANG=C.UTF-8 > + > + > ++fillchar() > ++{ > ++ local count="$1" > ++ local char="$2" > ++ eval 'printf "'"$char"'%.0s" {1..'"$count"'}' > ++} > ++ > + start_postsrsd_at() > + { > + echo 'tops3cr3t' > "$BATS_TMPDIR/postsrsd.secret" > + local faketime="$1" > + shift > +- faketime "${faketime}" ${POSTSRSD} -D -f 10001 -r 10002 -p > "$BATS_TMPDIR/postsrsd.pid" -s "$BATS_TMPDIR/postsrsd.secret" -d example.com > "$@" > ++ faketime "${faketime}" ${POSTSRSD} -D -t1 -f 10001 -r 10002 -p > "$BATS_TMPDIR/postsrsd.pid" -s "$BATS_TMPDIR/postsrsd.secret" -d example.com > "$@" > + } > + > + stop_postsrsd() > + { > +@@ -158,9 +165,9 @@ teardown() > + read<&9 line > + [[ "$line" =~ ^"500 Domain excluded" ]] > + } > + > +-@test "SRS invalid requests" { > ++@test "Malformed or invalid requests" { > + start_postsrsd_at "2020-01-01 00:01:00 UTC" > + exec 9<>/dev/tcp/127.0.0.1/10001 > + echo>&9 "get" > + read<&9 line > +@@ -172,5 +179,30 @@ teardown() > + exec 9<>/dev/tcp/127.0.0.1/10001 > + echo>&9 "get encoding%[email protected]" > + read<&9 line > + [[ "$line" =~ ^500 ]] > ++ exec 9<>/dev/tcp/127.0.0.1/10001 > ++ # Try to overflow the input buffer > ++ echo>&9 "get too_long@`fillchar 1024 a`.com" > ++ read<&9 line > ++ [[ "$line" =~ ^500 ]] > ++} > ++ > ++@test "Pipelining multiple requests" { > ++ start_postsrsd_at "2020-01-01 00:01:00 UTC" > ++ exec 9<>/dev/tcp/127.0.0.1/10001 > ++ # Send two requests at once and see if PostSRSd answers both > ++ echo>&9 -e "get [email protected]\nget [email protected]" > ++ read<&9 line > ++ [[ "$line" =~ ^200 ]] > ++ read<&9 line > ++ [[ "$line" =~ ^200 ]] > ++} > ++ > ++@test "Session timeout" { > ++ start_postsrsd_at "2020-01-01 00:01:00 UTC" > ++ exec 9<>/dev/tcp/127.0.0.1/10001 > ++ # Wait until PostSRSd disconnects due to inactivity > ++ sleep 2 > ++ echo >&9 "get [email protected]" > ++ ! read <&9 line > + } > diff -Nru postsrsd-1.10/debian/patches/series > postsrsd-1.10/debian/patches/series > --- postsrsd-1.10/debian/patches/series 2020-12-02 22:36:36.000000000 > +0100 > +++ postsrsd-1.10/debian/patches/series 2021-07-14 21:21:11.000000000 > +0200 > @@ -1 +1,2 @@ > 0001-Run-as-postsrsd-user-by-default.patch > +0002-SECURITY-Fix-DoS-on-overly-long-input-from-Postfix.patch -- Sebastian Ramacher
