151 lines
5.2 KiB
Diff
151 lines
5.2 KiB
Diff
From a35e092e24ee7632346a0e1b4a203c04d4cd2c62 Mon Sep 17 00:00:00 2001
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From: Iker Pedrosa <ipedrosa@redhat.com>
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Date: Mon, 24 Jan 2022 15:43:23 +0100
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Subject: [PATCH] pam_keyinit: thread-safe implementation
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* modules/pam_keyinit/pam_keyinit.c: Bypass setre*id() C library calls
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with kernel calls and change global variables definitions to be
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thread-safe.
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Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1997969
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Signed-off-by: Iker Pedrosa <ipedrosa@redhat.com>
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Co-Authored-By: Andreas Schneider <asn@samba.org>
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---
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modules/pam_keyinit/pam_keyinit.c | 60 ++++++++++++++++++++++---------
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1 file changed, 44 insertions(+), 16 deletions(-)
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diff --git a/modules/pam_keyinit/pam_keyinit.c b/modules/pam_keyinit/pam_keyinit.c
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index 92e4953b..df9804b9 100644
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--- a/modules/pam_keyinit/pam_keyinit.c
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+++ b/modules/pam_keyinit/pam_keyinit.c
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@@ -21,6 +21,7 @@
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#include <security/pam_modutil.h>
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#include <security/pam_ext.h>
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#include <sys/syscall.h>
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+#include <stdatomic.h>
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#define KEY_SPEC_SESSION_KEYRING -3 /* ID for session keyring */
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#define KEY_SPEC_USER_KEYRING -4 /* ID for UID-specific keyring */
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@@ -31,12 +32,12 @@
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#define KEYCTL_REVOKE 3 /* revoke a key */
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#define KEYCTL_LINK 8 /* link a key into a keyring */
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-static int my_session_keyring = 0;
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-static int session_counter = 0;
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-static int do_revoke = 0;
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-static uid_t revoke_as_uid;
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-static gid_t revoke_as_gid;
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-static int xdebug = 0;
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+static _Thread_local int my_session_keyring = 0;
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+static _Atomic int session_counter = 0;
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+static _Thread_local int do_revoke = 0;
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+static _Thread_local uid_t revoke_as_uid;
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+static _Thread_local gid_t revoke_as_gid;
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+static _Thread_local int xdebug = 0;
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static void debug(pam_handle_t *pamh, const char *fmt, ...)
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__attribute__((format(printf, 2, 3)));
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@@ -64,6 +65,33 @@ static void error(pam_handle_t *pamh, const char *fmt, ...)
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va_end(va);
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}
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+static int pam_setreuid(uid_t ruid, uid_t euid)
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+{
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+#if defined(SYS_setreuid32)
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+ return syscall(SYS_setreuid32, ruid, euid);
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+#else
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+ return syscall(SYS_setreuid, ruid, euid);
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+#endif
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+}
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+
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+static int pam_setregid(gid_t rgid, gid_t egid)
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+{
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+#if defined(SYS_setregid32)
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+ return syscall(SYS_setregid32, rgid, egid);
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+#else
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+ return syscall(SYS_setregid, rgid, egid);
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+#endif
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+}
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+
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+static int pam_setresuid(uid_t ruid, uid_t euid, uid_t suid)
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+{
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+#if defined(SYS_setresuid32)
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+ return syscall(SYS_setresuid32, ruid, euid, suid);
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+#else
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+ return syscall(SYS_setresuid, ruid, euid, suid);
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+#endif
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+}
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+
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/*
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* initialise the session keyring for this process
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*/
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@@ -140,14 +168,14 @@ static int kill_keyrings(pam_handle_t *pamh, int error_ret)
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/* switch to the real UID and GID so that we have permission to
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* revoke the key */
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- if (revoke_as_gid != old_gid && setregid(-1, revoke_as_gid) < 0) {
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+ if (revoke_as_gid != old_gid && pam_setregid(-1, revoke_as_gid) < 0) {
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error(pamh, "Unable to change GID to %d temporarily\n", revoke_as_gid);
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return error_ret;
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}
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- if (revoke_as_uid != old_uid && setresuid(-1, revoke_as_uid, old_uid) < 0) {
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+ if (revoke_as_uid != old_uid && pam_setresuid(-1, revoke_as_uid, old_uid) < 0) {
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error(pamh, "Unable to change UID to %d temporarily\n", revoke_as_uid);
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- if (getegid() != old_gid && setregid(-1, old_gid) < 0)
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+ if (getegid() != old_gid && pam_setregid(-1, old_gid) < 0)
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error(pamh, "Unable to change GID back to %d\n", old_gid);
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return error_ret;
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}
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@@ -157,12 +185,12 @@ static int kill_keyrings(pam_handle_t *pamh, int error_ret)
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}
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/* return to the original UID and GID (probably root) */
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- if (revoke_as_uid != old_uid && setreuid(-1, old_uid) < 0) {
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+ if (revoke_as_uid != old_uid && pam_setreuid(-1, old_uid) < 0) {
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error(pamh, "Unable to change UID back to %d\n", old_uid);
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ret = error_ret;
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}
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- if (revoke_as_gid != old_gid && setregid(-1, old_gid) < 0) {
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+ if (revoke_as_gid != old_gid && pam_setregid(-1, old_gid) < 0) {
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error(pamh, "Unable to change GID back to %d\n", old_gid);
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ret = error_ret;
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}
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@@ -215,14 +243,14 @@ static int do_keyinit(pam_handle_t *pamh, int argc, const char **argv, int error
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/* switch to the real UID and GID so that the keyring ends up owned by
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* the right user */
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- if (gid != old_gid && setregid(gid, -1) < 0) {
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+ if (gid != old_gid && pam_setregid(gid, -1) < 0) {
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error(pamh, "Unable to change GID to %d temporarily\n", gid);
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return error_ret;
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}
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- if (uid != old_uid && setreuid(uid, -1) < 0) {
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+ if (uid != old_uid && pam_setreuid(uid, -1) < 0) {
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error(pamh, "Unable to change UID to %d temporarily\n", uid);
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- if (setregid(old_gid, -1) < 0)
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+ if (pam_setregid(old_gid, -1) < 0)
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error(pamh, "Unable to change GID back to %d\n", old_gid);
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return error_ret;
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}
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@@ -230,12 +258,12 @@ static int do_keyinit(pam_handle_t *pamh, int argc, const char **argv, int error
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ret = init_keyrings(pamh, force, error_ret);
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/* return to the original UID and GID (probably root) */
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- if (uid != old_uid && setreuid(old_uid, -1) < 0) {
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+ if (uid != old_uid && pam_setreuid(old_uid, -1) < 0) {
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error(pamh, "Unable to change UID back to %d\n", old_uid);
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ret = error_ret;
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}
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- if (gid != old_gid && setregid(old_gid, -1) < 0) {
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+ if (gid != old_gid && pam_setregid(old_gid, -1) < 0) {
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error(pamh, "Unable to change GID back to %d\n", old_gid);
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ret = error_ret;
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}
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--
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2.35.1
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