From 6599d8f1264299ee595f2eaf4dc6a9aa2d7940d2 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 2 Mar 2022 11:57:02 -0500 Subject: [PATCH] Allow root-owned SSL private keys in libpq, not only the backend. This change makes libpq apply the same private-key-file ownership and permissions checks that we have used in the backend since commit 9a83564c5. Namely, that the private key can be owned by either the current user or root (with different file permissions allowed in the two cases). This allows system-wide management of key files, which is just as sensible on the client side as the server, particularly when the client is itself some application daemon. Sync the comments about this between libpq and the backend, too. Back-patch of a59c79564 and 50f03473e into all supported branches. David Steele Discussion: https://postgr.es/m/f4b7bc55-97ac-9e69-7398-335e212f7743@pgmasters.net --- doc/src/sgml/libpq.sgml | 26 ++++++++++----- src/backend/libpq/be-secure-common.c | 28 ++++++++--------- src/interfaces/libpq/fe-secure-openssl.c | 40 ++++++++++++++++++++++-- 3 files changed, 69 insertions(+), 25 deletions(-) diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml index 57d95d2020..2f6821a45f 100644 --- a/doc/src/sgml/libpq.sgml +++ b/doc/src/sgml/libpq.sgml @@ -7685,23 +7685,35 @@ ldap://ldap.acme.com/cn=dbserver,cn=hosts?pgconnectinfo?base?(objectclass=*) If the server attempts to verify the identity of the client by requesting the client's leaf certificate, - libpq will send the certificates stored in + libpq will send the certificate(s) stored in file ~/.postgresql/postgresql.crt in the user's home directory. The certificates must chain to the root certificate trusted by the server. A matching private key file ~/.postgresql/postgresql.key must also - be present. The private - key file must not allow any access to world or group; achieve this by the - command chmod 0600 ~/.postgresql/postgresql.key. + be present. On Microsoft Windows these files are named %APPDATA%\postgresql\postgresql.crt and - %APPDATA%\postgresql\postgresql.key, and there - is no special permissions check since the directory is presumed secure. + %APPDATA%\postgresql\postgresql.key. The location of the certificate and key files can be overridden by the - connection parameters sslcert and sslkey or the + connection parameters sslcert + and sslkey, or by the environment variables PGSSLCERT and PGSSLKEY. + + On Unix systems, the permissions on the private key file must disallow + any access to world or group; achieve this by a command such as + chmod 0600 ~/.postgresql/postgresql.key. + Alternatively, the file can be owned by root and have group read access + (that is, 0640 permissions). That setup is intended + for installations where certificate and key files are managed by the + operating system. The user of libpq should + then be made a member of the group that has access to those certificate + and key files. (On Microsoft Windows, there is no file permissions + check, since the %APPDATA%\postgresql directory is + presumed secure.) + + The first certificate in postgresql.crt must be the client's certificate because it must match the client's private key. diff --git a/src/backend/libpq/be-secure-common.c b/src/backend/libpq/be-secure-common.c index 94cdf4c887..7da0cfd1cf 100644 --- a/src/backend/libpq/be-secure-common.c +++ b/src/backend/libpq/be-secure-common.c @@ -143,6 +143,7 @@ check_ssl_key_file_permissions(const char *ssl_key_file, bool isServerStart) return false; } + /* Key file must be a regular file */ if (!S_ISREG(buf.st_mode)) { ereport(loglevel, @@ -153,9 +154,19 @@ check_ssl_key_file_permissions(const char *ssl_key_file, bool isServerStart) } /* - * Refuse to load key files owned by users other than us or root. + * Refuse to load key files owned by users other than us or root, and + * require no public access to the key file. If the file is owned by us, + * require mode 0600 or less. If owned by root, require 0640 or less to + * allow read access through either our gid or a supplementary gid that + * allows us to read system-wide certificates. * - * XXX surely we can check this on Windows somehow, too. + * Note that similar checks are performed in + * src/interfaces/libpq/fe-secure-openssl.c so any changes here may need + * to be made there as well. + * + * Ideally we would do similar permissions checks on Windows, but it is + * not clear how that would work since Unix-style permissions may not be + * available. */ #if !defined(WIN32) && !defined(__CYGWIN__) if (buf.st_uid != geteuid() && buf.st_uid != 0) @@ -166,20 +177,7 @@ check_ssl_key_file_permissions(const char *ssl_key_file, bool isServerStart) ssl_key_file))); return false; } -#endif - /* - * Require no public access to key file. If the file is owned by us, - * require mode 0600 or less. If owned by root, require 0640 or less to - * allow read access through our gid, or a supplementary gid that allows - * to read system-wide certificates. - * - * XXX temporarily suppress check when on Windows, because there may not - * be proper support for Unix-y file permissions. Need to think of a - * reasonable check to apply on Windows. (See also the data directory - * permission check in postmaster.c) - */ -#if !defined(WIN32) && !defined(__CYGWIN__) if ((buf.st_uid == geteuid() && buf.st_mode & (S_IRWXG | S_IRWXO)) || (buf.st_uid == 0 && buf.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO))) { diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c index 987fe02419..7348a62e46 100644 --- a/src/interfaces/libpq/fe-secure-openssl.c +++ b/src/interfaces/libpq/fe-secure-openssl.c @@ -1187,11 +1187,45 @@ initialize_SSL(PGconn *conn) fnbuf); return -1; } -#ifndef WIN32 - if (!S_ISREG(buf.st_mode) || buf.st_mode & (S_IRWXG | S_IRWXO)) + + /* Key file must be a regular file */ + if (!S_ISREG(buf.st_mode)) { printfPQExpBuffer(&conn->errorMessage, - libpq_gettext("private key file \"%s\" has group or world access; permissions should be u=rw (0600) or less\n"), + libpq_gettext("private key file \"%s\" is not a regular file"), + fnbuf); + return -1; + } + + /* + * Refuse to load key files owned by users other than us or root, and + * require no public access to the key file. If the file is owned by + * us, require mode 0600 or less. If owned by root, require 0640 or + * less to allow read access through either our gid or a supplementary + * gid that allows us to read system-wide certificates. + * + * Note that similar checks are performed in + * src/backend/libpq/be-secure-common.c so any changes here may need + * to be made there as well. + * + * Ideally we would do similar permissions checks on Windows, but it + * is not clear how that would work since Unix-style permissions may + * not be available. + */ +#if !defined(WIN32) && !defined(__CYGWIN__) + if (buf.st_uid != geteuid() && buf.st_uid != 0) + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("private key file \"%s\" must be owned by the current user or root\n"), + fnbuf); + return -1; + } + + if ((buf.st_uid == geteuid() && buf.st_mode & (S_IRWXG | S_IRWXO)) || + (buf.st_uid == 0 && buf.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO))) + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("private key file \"%s\" has group or world access; file must have permissions u=rw (0600) or less if owned by the current user, or permissions u=rw,g=r (0640) or less if owned by root\n"), fnbuf); return -1; }