Commit 8ad8223c authored by Luca Giambonini's avatar Luca Giambonini

added kwallet [skip-ci]

parent 6640b63e
Pipeline #3797 skipped
From 2134dec85ce19d6378d03cddfae9e5e464cb24c0 Mon Sep 17 00:00:00 2001
From: Albert Astals Cid <aacid@kde.org>
Date: Tue, 1 May 2018 12:29:02 +0200
Subject: Move salt creation to an unprivileged process
Opening files for writing as root is very tricky since through the power
of symlinks we can get tricked to write in places we don't want to and
we don't really need to be root to create the salt file
---
pam_kwallet.c | 121 ++++++++++++++++++++++++++++++++++------------------------
1 file changed, 71 insertions(+), 50 deletions(-)
diff --git a/pam_kwallet.c b/pam_kwallet.c
index 20d9603..083c9aa 100644
--- a/pam_kwallet.c
+++ b/pam_kwallet.c
@@ -82,7 +82,7 @@ const static char *envVar = "PAM_KWALLET_LOGIN";
static int argumentsParsed = -1;
-int kwallet_hash(const char *passphrase, struct passwd *userInfo, char *key);
+int kwallet_hash(pam_handle_t *pamh, const char *passphrase, struct passwd *userInfo, char *key);
static void parseArguments(int argc, const char **argv)
{
@@ -325,7 +325,7 @@ PAM_EXTERN int pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, cons
}
char *key = malloc(KWALLET_PAM_KEYSIZE);
- if (!key || kwallet_hash(password, userInfo, key) != 0) {
+ if (!key || kwallet_hash(pamh, password, userInfo, key) != 0) {
free(key);
pam_syslog(pamh, LOG_ERR, "%s: Fail into creating the hash", logPrefix);
return PAM_IGNORE;
@@ -352,6 +352,26 @@ PAM_EXTERN int pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, cons
return PAM_SUCCESS;
}
+static int drop_privileges(struct passwd *userInfo)
+{
+ /* When dropping privileges from root, the `setgroups` call will
+ * remove any extraneous groups. If we don't call this, then
+ * even though our uid has dropped, we may still have groups
+ * that enable us to do super-user things. This will fail if we
+ * aren't root, so don't bother checking the return value, this
+ * is just done as an optimistic privilege dropping function.
+ */
+ setgroups(0, NULL);
+
+ //Change to the user in case we are not it yet
+ if (setgid (userInfo->pw_gid) < 0 || setuid (userInfo->pw_uid) < 0 ||
+ setegid (userInfo->pw_gid) < 0 || seteuid (userInfo->pw_uid) < 0) {
+ return -1;
+ }
+
+ return 0;
+}
+
static void execute_kwallet(pam_handle_t *pamh, struct passwd *userInfo, int toWalletPipe[2], int envSocket)
{
//In the child pam_syslog does not work, using syslog directly
@@ -366,18 +386,8 @@ static void execute_kwallet(pam_handle_t *pamh, struct passwd *userInfo, int toW
//This is the side of the pipe PAM will send the hash to
close (toWalletPipe[1]);
- /* When dropping privileges from root, the `setgroups` call will
- * remove any extraneous groups. If we don't call this, then
- * even though our uid has dropped, we may still have groups
- * that enable us to do super-user things. This will fail if we
- * aren't root, so don't bother checking the return value, this
- * is just done as an optimistic privilege dropping function.
- */
- setgroups(0, NULL);
-
//Change to the user in case we are not it yet
- if (setgid (userInfo->pw_gid) < 0 || setuid (userInfo->pw_uid) < 0 ||
- setegid (userInfo->pw_gid) < 0 || seteuid (userInfo->pw_uid) < 0) {
+ if (drop_privileges(userInfo) < 0) {
syslog(LOG_ERR, "%s: could not set gid/uid/euid/egit for kwalletd", logPrefix);
goto cleanup;
}
@@ -619,7 +629,7 @@ PAM_EXTERN int pam_sm_chauthtok(pam_handle_t *pamh, int flags, int argc, const c
return PAM_SUCCESS;
}
-int mkpath(char *path, struct passwd *userInfo)
+static int mkpath(char *path)
{
struct stat sb;
char *slash;
@@ -639,10 +649,6 @@ int mkpath(char *path, struct passwd *userInfo)
errno != EEXIST)) {
syslog(LOG_ERR, "%s: Couldn't create directory: %s because: %d-%s", logPrefix, path, errno, strerror(errno));
return (-1);
- } else {
- if (chown(path, userInfo->pw_uid, userInfo->pw_gid) == -1) {
- syslog(LOG_INFO, "%s: Couldn't change ownership of: %s", logPrefix, path);
- }
}
} else if (!S_ISDIR(sb.st_mode)) {
return (-1);
@@ -654,34 +660,49 @@ int mkpath(char *path, struct passwd *userInfo)
return (0);
}
-static char* createNewSalt(const char *path, struct passwd *userInfo)
+static void createNewSalt(pam_handle_t *pamh, const char *path, struct passwd *userInfo)
{
- unlink(path);//in case the file already exists
+ const int pid = fork();
+ if (pid == -1) {
+ pam_syslog(pamh, LOG_ERR, "%s: Couldn't fork to create salt file", logPrefix);
+ } else if (pid == 0) {
+ // Child process
+ if (drop_privileges(userInfo) < 0) {
+ syslog(LOG_ERR, "%s: could not set gid/uid/euid/egit for salt file creation", logPrefix);
+ exit(-1);
+ }
- char *dir = strdup(path);
- dir[strlen(dir) - 14] = '\0';//remove kdewallet.salt
- mkpath(dir, userInfo);//create the path in case it does not exists
- free(dir);
+ unlink(path);//in case the file already exists
- char *salt = gcry_random_bytes(KWALLET_PAM_SALTSIZE, GCRY_STRONG_RANDOM);
- FILE *fd = fopen(path, "w");
+ char *dir = strdup(path);
+ dir[strlen(dir) - 14] = '\0';//remove kdewallet.salt
+ mkpath(dir); //create the path in case it does not exists
+ free(dir);
- //If the file can't be created
- if (fd == NULL) {
- syslog(LOG_ERR, "%s: Couldn't open file: %s because: %d-%s", logPrefix, path, errno, strerror(errno));
- return NULL;
- }
+ char *salt = gcry_random_bytes(KWALLET_PAM_SALTSIZE, GCRY_STRONG_RANDOM);
+ FILE *fd = fopen(path, "w");
- fwrite(salt, KWALLET_PAM_SALTSIZE, 1, fd);
- fclose(fd);
+ //If the file can't be created
+ if (fd == NULL) {
+ syslog(LOG_ERR, "%s: Couldn't open file: %s because: %d-%s", logPrefix, path, errno, strerror(errno));
+ exit(-2);
+ }
- if (chown(path, userInfo->pw_uid, userInfo->pw_gid) == -1) {
- syslog(LOG_ERR, "%s: Couldn't change ownership of the created salt file", logPrefix);
- }
+ fwrite(salt, KWALLET_PAM_SALTSIZE, 1, fd);
+ fclose(fd);
- return salt;
+ exit(0); // success
+ } else {
+ // pam process, just wait for child to finish
+ int status;
+ waitpid(pid, &status, 0);
+ if (status != 0) {
+ pam_syslog(pamh, LOG_ERR, "%s: Couldn't create salt file", logPrefix);
+ }
+ }
}
-int kwallet_hash(const char *passphrase, struct passwd *userInfo, char *key)
+
+int kwallet_hash(pam_handle_t *pamh, const char *passphrase, struct passwd *userInfo, char *key)
{
if (!gcry_check_version("1.5.0")) {
syslog(LOG_ERR, "%s-kwalletd: libcrypt version is too old", logPrefix);
@@ -700,19 +721,19 @@ int kwallet_hash(const char *passphrase, struct passwd *userInfo, char *key)
struct stat info;
char *salt = NULL;
if (stat(path, &info) != 0 || info.st_size == 0) {
- salt = createNewSalt(path, userInfo);
- } else {
- FILE *fd = fopen(path, "r");
- if (fd == NULL) {
- syslog(LOG_ERR, "%s: Couldn't open file: %s because: %d-%s", logPrefix, path, errno, strerror(errno));
- free(path);
- return 1;
- }
- salt = (char*) malloc(KWALLET_PAM_SALTSIZE);
- memset(salt, '\0', KWALLET_PAM_SALTSIZE);
- fread(salt, KWALLET_PAM_SALTSIZE, 1, fd);
- fclose(fd);
+ createNewSalt(pamh, path, userInfo);
}
+
+ FILE *fd = fopen(path, "r");
+ if (fd == NULL) {
+ syslog(LOG_ERR, "%s: Couldn't open file: %s because: %d-%s", logPrefix, path, errno, strerror(errno));
+ free(path);
+ return 1;
+ }
+ salt = (char*) malloc(KWALLET_PAM_SALTSIZE);
+ memset(salt, '\0', KWALLET_PAM_SALTSIZE);
+ fread(salt, KWALLET_PAM_SALTSIZE, 1, fd);
+ fclose(fd);
free(path);
if (salt == NULL) {
--
cgit v0.11.2
From 01d4143fda5bddb6dca37b23304dc239a5fb38b5 Mon Sep 17 00:00:00 2001
From: Albert Astals Cid <aacid@kde.org>
Date: Tue, 1 May 2018 12:32:24 +0200
Subject: Move socket creation to unprivileged codepath
We don't need to be creating the socket as root, and doing so,
specially having a chown is problematic security wise.
---
pam_kwallet.c | 77 ++++++++++++++++++++++++++++-------------------------------
1 file changed, 36 insertions(+), 41 deletions(-)
diff --git a/pam_kwallet.c b/pam_kwallet.c
index 083c9aa..b9c984a 100644
--- a/pam_kwallet.c
+++ b/pam_kwallet.c
@@ -372,13 +372,13 @@ static int drop_privileges(struct passwd *userInfo)
return 0;
}
-static void execute_kwallet(pam_handle_t *pamh, struct passwd *userInfo, int toWalletPipe[2], int envSocket)
+static void execute_kwallet(pam_handle_t *pamh, struct passwd *userInfo, int toWalletPipe[2], char *fullSocket)
{
//In the child pam_syslog does not work, using syslog directly
int x = 2;
//Close fd that are not of interest of kwallet
for (; x < 64; ++x) {
- if (x != toWalletPipe[0] && x != envSocket) {
+ if (x != toWalletPipe[0]) {
close (x);
}
}
@@ -392,6 +392,39 @@ static void execute_kwallet(pam_handle_t *pamh, struct passwd *userInfo, int toW
goto cleanup;
}
+ int envSocket;
+ if ((envSocket = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
+ pam_syslog(pamh, LOG_ERR, "%s: couldn't create socket", logPrefix);
+ return;
+ }
+
+ struct sockaddr_un local;
+ local.sun_family = AF_UNIX;
+
+ if (strlen(fullSocket) > sizeof(local.sun_path)) {
+ pam_syslog(pamh, LOG_ERR, "%s: socket path %s too long to open",
+ logPrefix, fullSocket);
+ free(fullSocket);
+ return;
+ }
+ strcpy(local.sun_path, fullSocket);
+ free(fullSocket);
+ fullSocket = NULL;
+ unlink(local.sun_path);//Just in case it exists from a previous login
+
+ pam_syslog(pamh, LOG_INFO, "%s: final socket path: %s", logPrefix, local.sun_path);
+
+ size_t len = strlen(local.sun_path) + sizeof(local.sun_family);
+ if (bind(envSocket, (struct sockaddr *)&local, len) == -1) {
+ pam_syslog(pamh, LOG_INFO, "%s-kwalletd: Couldn't bind to local file\n", logPrefix);
+ return;
+ }
+
+ if (listen(envSocket, 5) == -1) {
+ pam_syslog(pamh, LOG_INFO, "%s-kwalletd: Couldn't listen in socket\n", logPrefix);
+ return;
+ }
+
// Fork twice to daemonize kwallet
setsid();
pid_t pid = fork();
@@ -452,12 +485,6 @@ static void start_kwallet(pam_handle_t *pamh, struct passwd *userInfo, const cha
pam_syslog(pamh, LOG_ERR, "%s: Couldn't create pipes", logPrefix);
}
- int envSocket;
- if ((envSocket = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
- pam_syslog(pamh, LOG_ERR, "%s: couldn't create socket", logPrefix);
- return;
- }
-
#ifdef KWALLET5
const char *socketPrefix = "kwallet5";
#else
@@ -493,38 +520,6 @@ static void start_kwallet(pam_handle_t *pamh, struct passwd *userInfo, const cha
return;
}
- struct sockaddr_un local;
- local.sun_family = AF_UNIX;
-
- if (strlen(fullSocket) > sizeof(local.sun_path)) {
- pam_syslog(pamh, LOG_ERR, "%s: socket path %s too long to open",
- logPrefix, fullSocket);
- free(fullSocket);
- return;
- }
- strcpy(local.sun_path, fullSocket);
- free(fullSocket);
- fullSocket = NULL;
- unlink(local.sun_path);//Just in case it exists from a previous login
-
- pam_syslog(pamh, LOG_INFO, "%s: final socket path: %s", logPrefix, local.sun_path);
-
- size_t len = strlen(local.sun_path) + sizeof(local.sun_family);
- if (bind(envSocket, (struct sockaddr *)&local, len) == -1) {
- pam_syslog(pamh, LOG_INFO, "%s-kwalletd: Couldn't bind to local file\n", logPrefix);
- return;
- }
-
- if (listen(envSocket, 5) == -1) {
- pam_syslog(pamh, LOG_INFO, "%s-kwalletd: Couldn't listen in socket\n", logPrefix);
- return;
- }
-
- if (chown(local.sun_path, userInfo->pw_uid, userInfo->pw_gid) == -1) {
- pam_syslog(pamh, LOG_INFO, "%s: Couldn't change ownership of the socket", logPrefix);
- return;
- }
-
pid_t pid;
int status;
switch (pid = fork ()) {
@@ -534,7 +529,7 @@ static void start_kwallet(pam_handle_t *pamh, struct passwd *userInfo, const cha
//Child fork, will contain kwalletd
case 0:
- execute_kwallet(pamh, userInfo, toWalletPipe, envSocket);
+ execute_kwallet(pamh, userInfo, toWalletPipe, fullSocket);
/* Should never be reached */
break;
--
cgit v0.11.2
......@@ -6,7 +6,7 @@ pkgdesc='KWallet PAM integration'
arch=(x86_64)
url='https://projects.kde.org/kwallet-pam'
license=(LGPL)
depends=(pam libgcrypt socat)
depends=(socat kwallet)
makedepends=(extra-cmake-modules qt5-base)
groups=('plasma')
options=("debug")
......
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