From df8020b329eb57b7487ed1a8aa579fcd0d40ff34 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 1 Sep 2020 13:14:44 -0400 Subject: [PATCH] Teach libpq to handle arbitrary-length lines in .pgpass files. Historically there's been a hard-wired assumption here that no line of a .pgpass file could be as long as NAMEDATALEN*5 bytes. That's a bit shaky to start off with, because (a) there's no reason to suppose that host names fit in NAMEDATALEN, and (b) this figure fails to allow for backslash escape characters. However, it fails completely if someone wants to use a very long password, and we're now hearing reports of people wanting to use "security tokens" that can run up to several hundred bytes. Another angle is that the file is specified to allow comment lines, but there's no reason to assume that long comment lines aren't possible. Rather than guessing at what might be a more suitable limit, let's replace the fixed-size buffer with an expansible PQExpBuffer. That adds one malloc/free cycle to the typical use-case, but that's surely pretty cheap relative to the I/O this code has to do. Also, add TAP test cases to exercise this code, because there was no test coverage before. This reverts most of commit 2eb3bc588, as there's no longer a need for a warning message about overlength .pgpass lines. (I kept the explicit check for comment lines, though.) In HEAD and v13, this also fixes an oversight in 74a308cf5: there's not much point in explicit_bzero'ing the line buffer if we only do so in two of the three exit paths. Back-patch to all supported branches, except that the test case only goes back to v10 where src/test/authentication/ was added. Discussion: https://postgr.es/m/4187382.1598909041@sss.pgh.pa.us --- src/interfaces/libpq/fe-connect.c | 108 +++++++++++++--------- src/test/authentication/t/001_password.pl | 28 +++++- 2 files changed, 88 insertions(+), 48 deletions(-) diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c index c8ea59e5a2a..0287fb54bb5 100644 --- a/src/interfaces/libpq/fe-connect.c +++ b/src/interfaces/libpq/fe-connect.c @@ -6459,9 +6459,7 @@ passwordFromFile(const char *hostname, const char *port, const char *dbname, { FILE *fp; struct stat stat_buf; - -#define LINELEN NAMEDATALEN*5 - char buf[LINELEN]; + PQExpBufferData buf; if (dbname == NULL || dbname[0] == '\0') return NULL; @@ -6517,63 +6515,81 @@ passwordFromFile(const char *hostname, const char *port, const char *dbname, if (fp == NULL) return NULL; + /* Use an expansible buffer to accommodate any reasonable line length */ + initPQExpBuffer(&buf); + while (!feof(fp) && !ferror(fp)) { - char *t = buf, - *ret, - *p1, - *p2; - int len; - - if (fgets(buf, sizeof(buf), fp) == NULL) + /* Make sure there's a reasonable amount of room in the buffer */ + if (!enlargePQExpBuffer(&buf, 128)) break; - len = strlen(buf); + /* Read some data, appending it to what we already have */ + if (fgets(buf.data + buf.len, buf.maxlen - buf.len, fp) == NULL) + break; + buf.len += strlen(buf.data + buf.len); - /* Remove trailing newline */ - if (len > 0 && buf[len - 1] == '\n') - { - buf[--len] = '\0'; - /* Handle DOS-style line endings, too, even when not on Windows */ - if (len > 0 && buf[len - 1] == '\r') - buf[--len] = '\0'; - } - - if (len == 0) + /* If we don't yet have a whole line, loop around to read more */ + if (!(buf.len > 0 && buf.data[buf.len - 1] == '\n') && !feof(fp)) continue; - if ((t = pwdfMatchesString(t, hostname)) == NULL || - (t = pwdfMatchesString(t, port)) == NULL || - (t = pwdfMatchesString(t, dbname)) == NULL || - (t = pwdfMatchesString(t, username)) == NULL) - continue; - - /* Found a match. */ - ret = strdup(t); - fclose(fp); - - if (!ret) + /* ignore comments */ + if (buf.data[0] != '#') { - /* Out of memory. XXX: an error message would be nice. */ - return NULL; + char *t = buf.data; + int len = buf.len; + + /* Remove trailing newline */ + if (len > 0 && t[len - 1] == '\n') + { + t[--len] = '\0'; + /* Handle DOS-style line endings, too */ + if (len > 0 && t[len - 1] == '\r') + t[--len] = '\0'; + } + + if (len > 0 && + (t = pwdfMatchesString(t, hostname)) != NULL && + (t = pwdfMatchesString(t, port)) != NULL && + (t = pwdfMatchesString(t, dbname)) != NULL && + (t = pwdfMatchesString(t, username)) != NULL) + { + /* Found a match. */ + char *ret, + *p1, + *p2; + + ret = strdup(t); + + fclose(fp); + termPQExpBuffer(&buf); + + if (!ret) + { + /* Out of memory. XXX: an error message would be nice. */ + return NULL; + } + + /* De-escape password. */ + for (p1 = p2 = ret; *p1 != ':' && *p1 != '\0'; ++p1, ++p2) + { + if (*p1 == '\\' && p1[1] != '\0') + ++p1; + *p2 = *p1; + } + *p2 = '\0'; + + return ret; + } } - /* De-escape password. */ - for (p1 = p2 = ret; *p1 != ':' && *p1 != '\0'; ++p1, ++p2) - { - if (*p1 == '\\' && p1[1] != '\0') - ++p1; - *p2 = *p1; - } - *p2 = '\0'; - - return ret; + /* No match, reset buffer to prepare for next line. */ + buf.len = 0; } fclose(fp); + termPQExpBuffer(&buf); return NULL; - -#undef LINELEN } diff --git a/src/test/authentication/t/001_password.pl b/src/test/authentication/t/001_password.pl index 3a3b0eb7e80..5976d877936 100644 --- a/src/test/authentication/t/001_password.pl +++ b/src/test/authentication/t/001_password.pl @@ -17,7 +17,7 @@ if ($windows_os) } else { - plan tests => 8; + plan tests => 11; } @@ -45,7 +45,9 @@ sub test_role $status_string = 'success' if ($expected_res eq 0); - my $res = $node->psql('postgres', undef, extra_params => [ '-U', $role ]); + local $Test::Builder::Level = $Test::Builder::Level + 1; + + my $res = $node->psql('postgres', undef, extra_params => [ '-U', $role, '-w' ]); is($res, $expected_res, "authentication $status_string for method $method, role $role"); return; @@ -86,3 +88,25 @@ test_role($node, 'md5_role', 'scram-sha-256', 2); reset_pg_hba($node, 'md5'); test_role($node, 'scram_role', 'md5', 0); test_role($node, 'md5_role', 'md5', 0); + +# Test .pgpass processing; but use a temp file, don't overwrite the real one! +my $pgpassfile = "${TestLib::tmp_check}/pgpass"; + +delete $ENV{"PGPASSWORD"}; +$ENV{"PGPASSFILE"} = $pgpassfile; + +append_to_file($pgpassfile, qq! +# This very long comment is just here to exercise handling of long lines in the file. This very long comment is just here to exercise handling of long lines in the file. This very long comment is just here to exercise handling of long lines in the file. This very long comment is just here to exercise handling of long lines in the file. This very long comment is just here to exercise handling of long lines in the file. +*:*:postgres:scram_role:pass:this is not part of the password. +!); +chmod 0600, $pgpassfile or die; + +reset_pg_hba($node, 'password'); +test_role($node, 'scram_role', 'password from pgpass', 0); +test_role($node, 'md5_role', 'password from pgpass', 2); + +append_to_file($pgpassfile, qq! +*:*:*:md5_role:p\\ass +!); + +test_role($node, 'md5_role', 'password from pgpass', 0);