diff --git a/src/tacacs/pam/0007-handle-bad-password-set-by-sshd.patch b/src/tacacs/pam/0007-handle-bad-password-set-by-sshd.patch new file mode 100644 index 000000000000..36a96da77ac5 --- /dev/null +++ b/src/tacacs/pam/0007-handle-bad-password-set-by-sshd.patch @@ -0,0 +1,133 @@ +From f2687e7a442c83e19190695021fb9a60fe07ba60 Mon Sep 17 00:00:00 2001 +From: Renuka Manavalan +Date: Wed, 17 Nov 2021 02:31:45 +0000 +Subject: [PATCH] handle bad password set by sshd + +--- + pam_tacplus.c | 11 +++++++++-- + support.c | 37 +++++++++++++++++++++++++++++++++++++ + support.h | 1 + + tacc.c | 4 ++-- + 4 files changed, 49 insertions(+), 4 deletions(-) + +diff --git a/pam_tacplus.c b/pam_tacplus.c +index ec8ea27..014421b 100644 +--- a/pam_tacplus.c ++++ b/pam_tacplus.c +@@ -251,6 +251,13 @@ int pam_sm_authenticate (pam_handle_t * pamh, int flags, + return PAM_CRED_INSUFFICIENT; + } + ++ if (validate_not_sshd_bad_pass(pass) != PAM_SUCCESS) { ++ syslog(LOG_ERR, "auth fail: Password incorrect"); ++ memset(pass, 0, strlen (pass)); ++ free(pass); ++ return PAM_AUTH_ERR; ++ } ++ + retval = pam_set_item (pamh, PAM_AUTHTOK, pass); + if (retval != PAM_SUCCESS) { + _pam_log(LOG_ERR, "unable to set password"); +@@ -483,7 +490,7 @@ int pam_sm_authenticate (pam_handle_t * pamh, int flags, + syslog(LOG_DEBUG, "%s: exit with pam status: %d", __FUNCTION__, status); + + if (NULL != pass) { +- bzero(pass, strlen (pass)); ++ memset(pass, 0, strlen (pass)); + free(pass); + pass = NULL; + } +@@ -979,7 +986,7 @@ finish: + syslog(LOG_DEBUG, "%s: exit with pam status: %d", __FUNCTION__, status); + + if (NULL != pass) { +- bzero(pass, strlen(pass)); ++ memset(pass, 0, strlen (pass)); + free(pass); + pass = NULL; + } +diff --git a/support.c b/support.c +index 3e55e2f..09d09bf 100644 +--- a/support.c ++++ b/support.c +@@ -108,6 +108,43 @@ int converse(pam_handle_t * pamh, int nargs, const struct pam_message *message, + return retval; + } + ++/* ++ * Ref: From ++ * For future archive searchers: ++ * > Why does OpenSSH replaces the password entered by the user with the ++ * > bad password - "\b\n\r\177INCORRECT ++ * ++ * There are some situations where sshd determines a user can't log in. ++ * Typical samples of that are DenyUsers or PermitRootLogin. ++ * In those cases sshd *still* calls PAM, so that delays set by it are ++ * still performed to the user (without leaking info about accounts ++ * existing, disabled, etc.). But in order to ensure it can't succeed, ++ * replaces the password with that impossible one. ++ * ++ */ ++int validate_not_sshd_bad_pass(const char *pass) ++{ ++ const char *SSHD_BAD_PASS = "\010\012\015\177INCORRECT"; ++ const int SSHD_BAD_PASS_LEN = strlen(SSHD_BAD_PASS); ++ ++ int len = strlen(pass); ++ const char *p = pass; ++ ++ if (len == 0) ++ return PAM_SUCCESS; ++ ++ while (len > 0) { ++ int l = len < SSHD_BAD_PASS_LEN ? len : SSHD_BAD_PASS_LEN; ++ ++ if (strncmp(p, SSHD_BAD_PASS, l) != 0) ++ return PAM_SUCCESS; ++ ++ len -= l; ++ p += l; ++ } ++ return PAM_AUTH_ERR; ++} ++ + /* stolen from pam_stress */ + int tacacs_get_password (pam_handle_t * pamh, int flags + ,int ctrl, char **password) { +diff --git a/support.h b/support.h +index 09b8a85..cb04a4f 100644 +--- a/support.h ++++ b/support.h +@@ -42,6 +42,7 @@ extern struct addrinfo *tac_source_addr; + int _pam_parse (int, const char **); + unsigned long _resolve_name (char *); + unsigned long _getserveraddr (char *serv); ++int validate_not_sshd_bad_pass(const char *pass); + int tacacs_get_password (pam_handle_t *, int, int, char **); + int converse (pam_handle_t *, int, const struct pam_message *, struct pam_response **); + void _pam_log (int, const char *, ...); +diff --git a/tacc.c b/tacc.c +index fcc7d8c..bf0f2a3 100644 +--- a/tacc.c ++++ b/tacc.c +@@ -181,7 +181,7 @@ int main(int argc, char **argv) { + break; + case 'L': + // tac_login is a global variable initialized in libtac +- bzero(tac_login, sizeof(tac_login)); ++ memset(tac_login, 0, sizeof(tac_login)); + strncpy(tac_login, optarg, sizeof(tac_login) - 1); + break; + case 'p': +@@ -312,7 +312,7 @@ int main(int argc, char **argv) { + } + + /* we no longer need the password in our address space */ +- bzero(pass, strlen(pass)); ++ memset(pass, 0, strlen(pass)); + pass = NULL; + + if (do_account) { +-- +2.17.1 + diff --git a/src/tacacs/pam/Makefile b/src/tacacs/pam/Makefile index 503bdcb864f0..843b75cc2f3d 100644 --- a/src/tacacs/pam/Makefile +++ b/src/tacacs/pam/Makefile @@ -20,6 +20,7 @@ $(addprefix $(DEST)/, $(MAIN_TARGET)): $(DEST)/% : git apply ../0004-management-vrf-support.patch git apply ../0005-pam-Modify-parsing-of-IP-address-and-port-number-to-.patch git apply ../0006-Add-support-for-source-ip-address.patch + git apply ../0007-handle-bad-password-set-by-sshd.patch dpkg-buildpackage -rfakeroot -b -us -uc -j$(SONIC_CONFIG_MAKE_JOBS) --admindir $(SONIC_DPKG_ADMINDIR) popd