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* [glibc/maskray/grte] Update passwd.borg handling to use passwd.borg.real
@ 2021-08-28 0:32 Fangrui Song
0 siblings, 0 replies; 3+ messages in thread
From: Fangrui Song @ 2021-08-28 0:32 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=86079708ee6532d458cdb1107787b6587cbd3906
commit 86079708ee6532d458cdb1107787b6587cbd3906
Author: Stan Shebs <stanshebs@google.com>
Date: Fri Dec 20 13:58:35 2019 -0800
Update passwd.borg handling to use passwd.borg.real
Diff:
---
nss/nss_borg/borg-pwd.c | 215 ++++++++++++++++++++++++++++++++++--------------
1 file changed, 151 insertions(+), 64 deletions(-)
diff --git a/nss/nss_borg/borg-pwd.c b/nss/nss_borg/borg-pwd.c
index a0eb0e3954..2e50b287a9 100644
--- a/nss/nss_borg/borg-pwd.c
+++ b/nss/nss_borg/borg-pwd.c
@@ -2,58 +2,85 @@
// /etc/passwd.borg and /etc/passwd.borg.base
// passwd.borg.base is a subset of passwd.borg that is used as a fallback.
-#include <stdio.h>
-#include <pwd.h>
-#include <sys/types.h>
-#include <nss.h>
#include <errno.h>
+#include <nss.h>
+#include <pwd.h>
+#include <stdio.h>
#include <string.h>
+#include <sys/types.h>
+#include <syslog.h>
#include <libc-lock.h>
-__libc_lock_define_initialized (static, lock)
-#define NSSBORG_LOCK __libc_lock_lock (lock)
-#define NSSBORG_UNLOCK __libc_lock_unlock (lock);
+__libc_lock_define_initialized(static, lock)
+#define NSSBORG_LOCK __libc_lock_lock(lock)
+#define NSSBORG_UNLOCK __libc_lock_unlock(lock);
+
+#define EXEC_NAME_SIZE 4096
static FILE *f;
static FILE *fb;
-
+static bool fb_eof;
+static FILE *fbr;
+static bool fbr_eof;
+static char exec_name[EXEC_NAME_SIZE];
+
+// This library will log into syslog any attempt to fetch a username from
+// /etc/passwd.borg file, but only if /etc/passwd.borg.real file is present.
+// This module makes the user lookup in following order:
+// /etc/passwd.borg.real
+// /etc/passwd.borg.base
+// /etc/passwd.borg
+
+
+// non_borg_user_lookup_warn is supposed to prevent log spew from a single
+// process.
+static int non_borg_user_lookup_warn = 0;
+
+#define LOGNSS(priority, fmt, ...) \
+ do { \
+ openlog("nss_borg", LOG_PID, 0); \
+ syslog(LOG_USER | priority, fmt, ##__VA_ARGS__); \
+ closelog(); \
+ } while (0)
#define DEBUG(fmt, ...)
+#define WARN(fmt, ...) LOGNSS(LOG_WARNING, fmt, ##__VA_ARGS__)
// _nss_borg_setpwent_locked()
// Internal setup routine
-
static enum nss_status _nss_borg_setpwent_locked(void) {
-
+ int readlink_ret;
DEBUG("Opening passwd.borg\n");
f = fopen("/etc/passwd.borg", "r");
DEBUG("Opening passwd.borg.base\n");
fb = fopen("/etc/passwd.borg.base", "r");
+ fb_eof = false;
+
+ DEBUG("Opening passwd.borg.real\n");
+ fbr = fopen("/etc/passwd.borg.real", "r");
+ fbr_eof = false;
+
+ DEBUG("Reading /proc/self/exe");
+ // readlink does not append null-byte, so we reserve last byte for it.
+ readlink_ret = readlink("/proc/self/exe", exec_name,
+ sizeof(exec_name) - 1);
+ if (readlink_ret == -1) {
+ DEBUG("Failed to readlink /proc/self/exe error: %d", errno);
+ strncpy(exec_name, "__unknown__", sizeof(exec_name));
+ } else {
+ exec_name[readlink_ret] = '\0';
+ }
- if (f||fb) {
+ if (f || fb || fbr) {
return NSS_STATUS_SUCCESS;
} else {
return NSS_STATUS_UNAVAIL;
}
}
-// _nss_borg_setpwent()
-// Called by NSS to open the passwd file
-// Oddly, NSS passes a boolean saying whether to keep the database file open; ignore it
-
-enum nss_status _nss_borg_setpwent(int stayopen) {
- enum nss_status ret;
- NSSBORG_LOCK;
- ret = _nss_borg_setpwent_locked();
- NSSBORG_UNLOCK;
- return ret;
-}
-
// _nss_borg_endpwent_locked()
// Internal close routine
-
static enum nss_status _nss_borg_endpwent_locked(void) {
-
DEBUG("Closing passwd.borg\n");
if (f) {
fclose(f);
@@ -64,40 +91,62 @@ static enum nss_status _nss_borg_endpwent_locked(void) {
fclose(fb);
fb = NULL;
}
+ DEBUG("Closing passwd.borg.real\n");
+ if (fbr) {
+ fclose(fbr);
+ fbr = NULL;
+ }
return NSS_STATUS_SUCCESS;
}
-// _nss_borg_endpwent()
-// Called by NSS to close the passwd file
-
-enum nss_status _nss_borg_endpwent(void) {
- enum nss_status ret;
- NSSBORG_LOCK;
- ret = _nss_borg_endpwent_locked();
- NSSBORG_UNLOCK;
- return ret;
+// Called internally. It's a wrapper around fgetpwent_r that prevents from
+// multiple read calls once EOF was reached (b/72036184)
+static int _nss_borg_fgetpwent_r_eof(FILE *fp, struct passwd *pwbuf,
+ char *buf, size_t buflen,
+ struct passwd **pwbufp, bool *eof) {
+ if (*eof) {
+ *pwbufp = NULL;
+ return ENOENT;
+ } else {
+ int ret = fgetpwent_r(fp, pwbuf, buf, buflen, pwbufp);
+ if (ret == ENOENT) {
+ *eof = true;
+ }
+ return ret;
+ }
}
// _nss_borg_getpwent_r_locked()
// Called internally to return the next entry from the passwd file
-
static enum nss_status _nss_borg_getpwent_r_locked(struct passwd *result,
char *buffer, size_t buflen,
- int *errnop) {
-
+ int *errnop,
+ int *non_borg_user) {
enum nss_status ret;
// Save a copy of the buffer address, in case first call errors
// and sets it to 0.
struct passwd *sparecopy = result;
- if (
- f != NULL && (fgetpwent_r(f, result, buffer, buflen, &result) == 0)) {
- DEBUG("Returning borg user %d:%s\n", result->pw_uid, result->pw_name);
+ if (fbr != NULL && (_nss_borg_fgetpwent_r_eof(fbr, result, buffer, buflen,
+ &result, &fbr_eof) == 0)) {
+ DEBUG("Returning real borg user %d:%s\n", result->pw_uid, result->pw_name);
+ ret = NSS_STATUS_SUCCESS;
+ } else if (
+ // Yes, this is one of those cases where an assign makes sense.
+ fb != NULL && (result = sparecopy) &&
+ (_nss_borg_fgetpwent_r_eof(fb, result, buffer, buflen, &result,
+ &fb_eof) == 0)) {
+ DEBUG("Returning base borg user %d:%s\n", result->pw_uid, result->pw_name);
ret = NSS_STATUS_SUCCESS;
} else if (
- // Yes, this is one of those cases where an assign makes sense.
- // NB: passwd.borg.base is not ordered by UID as of cl/201005022.
- fb != NULL && (result = sparecopy) && (fgetpwent_r(fb, result, buffer, buflen, &result) == 0)) {
- DEBUG("Returning base user %d:%s\n", result->pw_uid, result->pw_name);
+ // Yes, this is one of those cases where an assign makes sense.
+ // NB: passwd.borg.base is not ordered by UID as of cl/201005022.
+ f != NULL && (result = sparecopy) &&
+ (fgetpwent_r(f, result, buffer, buflen, &result) == 0)) {
+ DEBUG("Returning non borg user %d:%s\n", result->pw_uid, result->pw_name);
+ // Log only if passwd.borg.real file is present.
+ if (fbr) {
+ *non_borg_user = 1;
+ }
ret = NSS_STATUS_SUCCESS;
} else {
*errnop = errno;
@@ -114,36 +163,70 @@ static enum nss_status _nss_borg_getpwent_r_locked(struct passwd *result,
return ret;
}
+// All methods below are public interface of this library.
+
+// _nss_borg_setpwent()
+// Called by NSS to open the passwd file
+// Oddly, NSS passes a boolean saying whether to keep the database file open;
+// ignore it
+enum nss_status _nss_borg_setpwent(int stayopen) {
+ enum nss_status ret;
+ NSSBORG_LOCK;
+ ret = _nss_borg_setpwent_locked();
+ NSSBORG_UNLOCK;
+ return ret;
+}
+
+// _nss_borg_endpwent()
+// Called by NSS to close the passwd file
+enum nss_status _nss_borg_endpwent(void) {
+ enum nss_status ret;
+ NSSBORG_LOCK;
+ ret = _nss_borg_endpwent_locked();
+ NSSBORG_UNLOCK;
+ return ret;
+}
+
// _nss_borg_getpwent_r()
// Called by NSS (I think) to look up next entry in passwd file
-enum nss_status _nss_borg_getpwent_r(struct passwd *result,
- char *buffer, size_t buflen,
- int *errnop) {
+enum nss_status _nss_borg_getpwent_r(struct passwd *result, char *buffer,
+ size_t buflen, int *errnop) {
enum nss_status ret;
+ int non_borg_user = 0;
NSSBORG_LOCK;
- ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop);
+ ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop,
+ &non_borg_user);
+ if (non_borg_user && !non_borg_user_lookup_warn) {
+ non_borg_user_lookup_warn = 1;
+ WARN("Reached non borg section in getpwent call "
+ "in process: %s running as: %d\n", exec_name, getuid());
+ }
NSSBORG_UNLOCK;
return ret;
}
// _nss_borg_getpwuid_r()
-// Find a user account by uid
-
+// Called by NSS to find a user account by uid
enum nss_status _nss_borg_getpwuid_r(uid_t uid, struct passwd *result,
- char *buffer, size_t buflen,
- int *errnop) {
-
+ char *buffer, size_t buflen, int *errnop) {
enum nss_status ret;
+ int non_borg_user = 0;
NSSBORG_LOCK;
ret = _nss_borg_setpwent_locked();
DEBUG("Looking for uid %d\n", uid);
if (ret == NSS_STATUS_SUCCESS) {
- while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop))
- == NSS_STATUS_SUCCESS) {
- if (result->pw_uid == uid)
+ while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop,
+ &non_borg_user)) ==
+ NSS_STATUS_SUCCESS) {
+ if (result->pw_uid == uid) {
+ if (non_borg_user) {
+ WARN("Returning non borg user %d:%s in process: %s running as: %d\n",
+ result->pw_uid, result->pw_name, exec_name, getuid());
+ }
break;
+ }
}
}
@@ -154,23 +237,27 @@ enum nss_status _nss_borg_getpwuid_r(uid_t uid, struct passwd *result,
}
// _nss_borg_getpwnam_r()
-// Find a user account by name
-
+// Called by NSS to find a user account by name
enum nss_status _nss_borg_getpwnam_r(const char *name, struct passwd *result,
- char *buffer, size_t buflen,
- int *errnop) {
-
+ char *buffer, size_t buflen, int *errnop) {
enum nss_status ret;
+ int non_borg_user = 0;
NSSBORG_LOCK;
ret = _nss_borg_setpwent_locked();
DEBUG("Looking for user %s\n", name);
if (ret == NSS_STATUS_SUCCESS) {
- while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop))
- == NSS_STATUS_SUCCESS) {
- if (!strcmp(result->pw_name, name))
+ while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop,
+ &non_borg_user)) ==
+ NSS_STATUS_SUCCESS) {
+ if (!strcmp(result->pw_name, name)) {
+ if (non_borg_user) {
+ WARN("Returning non borg user %d:%s in process: %s running as: %d\n",
+ result->pw_uid, result->pw_name, exec_name, getuid());
+ }
break;
+ }
}
}
^ permalink raw reply [flat|nested] 3+ messages in thread
* [glibc/maskray/grte] Update passwd.borg handling to use passwd.borg.real
@ 2021-08-28 0:28 Fangrui Song
0 siblings, 0 replies; 3+ messages in thread
From: Fangrui Song @ 2021-08-28 0:28 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f2cb1ce4ea828cda665403f7f119850de51622e2
commit f2cb1ce4ea828cda665403f7f119850de51622e2
Author: Stan Shebs <stanshebs@google.com>
Date: Fri Dec 20 13:58:35 2019 -0800
Update passwd.borg handling to use passwd.borg.real
Diff:
---
nss/nss_borg/borg-pwd.c | 215 ++++++++++++++++++++++++++++++++++--------------
1 file changed, 151 insertions(+), 64 deletions(-)
diff --git a/nss/nss_borg/borg-pwd.c b/nss/nss_borg/borg-pwd.c
index a0eb0e3954..2e50b287a9 100644
--- a/nss/nss_borg/borg-pwd.c
+++ b/nss/nss_borg/borg-pwd.c
@@ -2,58 +2,85 @@
// /etc/passwd.borg and /etc/passwd.borg.base
// passwd.borg.base is a subset of passwd.borg that is used as a fallback.
-#include <stdio.h>
-#include <pwd.h>
-#include <sys/types.h>
-#include <nss.h>
#include <errno.h>
+#include <nss.h>
+#include <pwd.h>
+#include <stdio.h>
#include <string.h>
+#include <sys/types.h>
+#include <syslog.h>
#include <libc-lock.h>
-__libc_lock_define_initialized (static, lock)
-#define NSSBORG_LOCK __libc_lock_lock (lock)
-#define NSSBORG_UNLOCK __libc_lock_unlock (lock);
+__libc_lock_define_initialized(static, lock)
+#define NSSBORG_LOCK __libc_lock_lock(lock)
+#define NSSBORG_UNLOCK __libc_lock_unlock(lock);
+
+#define EXEC_NAME_SIZE 4096
static FILE *f;
static FILE *fb;
-
+static bool fb_eof;
+static FILE *fbr;
+static bool fbr_eof;
+static char exec_name[EXEC_NAME_SIZE];
+
+// This library will log into syslog any attempt to fetch a username from
+// /etc/passwd.borg file, but only if /etc/passwd.borg.real file is present.
+// This module makes the user lookup in following order:
+// /etc/passwd.borg.real
+// /etc/passwd.borg.base
+// /etc/passwd.borg
+
+
+// non_borg_user_lookup_warn is supposed to prevent log spew from a single
+// process.
+static int non_borg_user_lookup_warn = 0;
+
+#define LOGNSS(priority, fmt, ...) \
+ do { \
+ openlog("nss_borg", LOG_PID, 0); \
+ syslog(LOG_USER | priority, fmt, ##__VA_ARGS__); \
+ closelog(); \
+ } while (0)
#define DEBUG(fmt, ...)
+#define WARN(fmt, ...) LOGNSS(LOG_WARNING, fmt, ##__VA_ARGS__)
// _nss_borg_setpwent_locked()
// Internal setup routine
-
static enum nss_status _nss_borg_setpwent_locked(void) {
-
+ int readlink_ret;
DEBUG("Opening passwd.borg\n");
f = fopen("/etc/passwd.borg", "r");
DEBUG("Opening passwd.borg.base\n");
fb = fopen("/etc/passwd.borg.base", "r");
+ fb_eof = false;
+
+ DEBUG("Opening passwd.borg.real\n");
+ fbr = fopen("/etc/passwd.borg.real", "r");
+ fbr_eof = false;
+
+ DEBUG("Reading /proc/self/exe");
+ // readlink does not append null-byte, so we reserve last byte for it.
+ readlink_ret = readlink("/proc/self/exe", exec_name,
+ sizeof(exec_name) - 1);
+ if (readlink_ret == -1) {
+ DEBUG("Failed to readlink /proc/self/exe error: %d", errno);
+ strncpy(exec_name, "__unknown__", sizeof(exec_name));
+ } else {
+ exec_name[readlink_ret] = '\0';
+ }
- if (f||fb) {
+ if (f || fb || fbr) {
return NSS_STATUS_SUCCESS;
} else {
return NSS_STATUS_UNAVAIL;
}
}
-// _nss_borg_setpwent()
-// Called by NSS to open the passwd file
-// Oddly, NSS passes a boolean saying whether to keep the database file open; ignore it
-
-enum nss_status _nss_borg_setpwent(int stayopen) {
- enum nss_status ret;
- NSSBORG_LOCK;
- ret = _nss_borg_setpwent_locked();
- NSSBORG_UNLOCK;
- return ret;
-}
-
// _nss_borg_endpwent_locked()
// Internal close routine
-
static enum nss_status _nss_borg_endpwent_locked(void) {
-
DEBUG("Closing passwd.borg\n");
if (f) {
fclose(f);
@@ -64,40 +91,62 @@ static enum nss_status _nss_borg_endpwent_locked(void) {
fclose(fb);
fb = NULL;
}
+ DEBUG("Closing passwd.borg.real\n");
+ if (fbr) {
+ fclose(fbr);
+ fbr = NULL;
+ }
return NSS_STATUS_SUCCESS;
}
-// _nss_borg_endpwent()
-// Called by NSS to close the passwd file
-
-enum nss_status _nss_borg_endpwent(void) {
- enum nss_status ret;
- NSSBORG_LOCK;
- ret = _nss_borg_endpwent_locked();
- NSSBORG_UNLOCK;
- return ret;
+// Called internally. It's a wrapper around fgetpwent_r that prevents from
+// multiple read calls once EOF was reached (b/72036184)
+static int _nss_borg_fgetpwent_r_eof(FILE *fp, struct passwd *pwbuf,
+ char *buf, size_t buflen,
+ struct passwd **pwbufp, bool *eof) {
+ if (*eof) {
+ *pwbufp = NULL;
+ return ENOENT;
+ } else {
+ int ret = fgetpwent_r(fp, pwbuf, buf, buflen, pwbufp);
+ if (ret == ENOENT) {
+ *eof = true;
+ }
+ return ret;
+ }
}
// _nss_borg_getpwent_r_locked()
// Called internally to return the next entry from the passwd file
-
static enum nss_status _nss_borg_getpwent_r_locked(struct passwd *result,
char *buffer, size_t buflen,
- int *errnop) {
-
+ int *errnop,
+ int *non_borg_user) {
enum nss_status ret;
// Save a copy of the buffer address, in case first call errors
// and sets it to 0.
struct passwd *sparecopy = result;
- if (
- f != NULL && (fgetpwent_r(f, result, buffer, buflen, &result) == 0)) {
- DEBUG("Returning borg user %d:%s\n", result->pw_uid, result->pw_name);
+ if (fbr != NULL && (_nss_borg_fgetpwent_r_eof(fbr, result, buffer, buflen,
+ &result, &fbr_eof) == 0)) {
+ DEBUG("Returning real borg user %d:%s\n", result->pw_uid, result->pw_name);
+ ret = NSS_STATUS_SUCCESS;
+ } else if (
+ // Yes, this is one of those cases where an assign makes sense.
+ fb != NULL && (result = sparecopy) &&
+ (_nss_borg_fgetpwent_r_eof(fb, result, buffer, buflen, &result,
+ &fb_eof) == 0)) {
+ DEBUG("Returning base borg user %d:%s\n", result->pw_uid, result->pw_name);
ret = NSS_STATUS_SUCCESS;
} else if (
- // Yes, this is one of those cases where an assign makes sense.
- // NB: passwd.borg.base is not ordered by UID as of cl/201005022.
- fb != NULL && (result = sparecopy) && (fgetpwent_r(fb, result, buffer, buflen, &result) == 0)) {
- DEBUG("Returning base user %d:%s\n", result->pw_uid, result->pw_name);
+ // Yes, this is one of those cases where an assign makes sense.
+ // NB: passwd.borg.base is not ordered by UID as of cl/201005022.
+ f != NULL && (result = sparecopy) &&
+ (fgetpwent_r(f, result, buffer, buflen, &result) == 0)) {
+ DEBUG("Returning non borg user %d:%s\n", result->pw_uid, result->pw_name);
+ // Log only if passwd.borg.real file is present.
+ if (fbr) {
+ *non_borg_user = 1;
+ }
ret = NSS_STATUS_SUCCESS;
} else {
*errnop = errno;
@@ -114,36 +163,70 @@ static enum nss_status _nss_borg_getpwent_r_locked(struct passwd *result,
return ret;
}
+// All methods below are public interface of this library.
+
+// _nss_borg_setpwent()
+// Called by NSS to open the passwd file
+// Oddly, NSS passes a boolean saying whether to keep the database file open;
+// ignore it
+enum nss_status _nss_borg_setpwent(int stayopen) {
+ enum nss_status ret;
+ NSSBORG_LOCK;
+ ret = _nss_borg_setpwent_locked();
+ NSSBORG_UNLOCK;
+ return ret;
+}
+
+// _nss_borg_endpwent()
+// Called by NSS to close the passwd file
+enum nss_status _nss_borg_endpwent(void) {
+ enum nss_status ret;
+ NSSBORG_LOCK;
+ ret = _nss_borg_endpwent_locked();
+ NSSBORG_UNLOCK;
+ return ret;
+}
+
// _nss_borg_getpwent_r()
// Called by NSS (I think) to look up next entry in passwd file
-enum nss_status _nss_borg_getpwent_r(struct passwd *result,
- char *buffer, size_t buflen,
- int *errnop) {
+enum nss_status _nss_borg_getpwent_r(struct passwd *result, char *buffer,
+ size_t buflen, int *errnop) {
enum nss_status ret;
+ int non_borg_user = 0;
NSSBORG_LOCK;
- ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop);
+ ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop,
+ &non_borg_user);
+ if (non_borg_user && !non_borg_user_lookup_warn) {
+ non_borg_user_lookup_warn = 1;
+ WARN("Reached non borg section in getpwent call "
+ "in process: %s running as: %d\n", exec_name, getuid());
+ }
NSSBORG_UNLOCK;
return ret;
}
// _nss_borg_getpwuid_r()
-// Find a user account by uid
-
+// Called by NSS to find a user account by uid
enum nss_status _nss_borg_getpwuid_r(uid_t uid, struct passwd *result,
- char *buffer, size_t buflen,
- int *errnop) {
-
+ char *buffer, size_t buflen, int *errnop) {
enum nss_status ret;
+ int non_borg_user = 0;
NSSBORG_LOCK;
ret = _nss_borg_setpwent_locked();
DEBUG("Looking for uid %d\n", uid);
if (ret == NSS_STATUS_SUCCESS) {
- while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop))
- == NSS_STATUS_SUCCESS) {
- if (result->pw_uid == uid)
+ while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop,
+ &non_borg_user)) ==
+ NSS_STATUS_SUCCESS) {
+ if (result->pw_uid == uid) {
+ if (non_borg_user) {
+ WARN("Returning non borg user %d:%s in process: %s running as: %d\n",
+ result->pw_uid, result->pw_name, exec_name, getuid());
+ }
break;
+ }
}
}
@@ -154,23 +237,27 @@ enum nss_status _nss_borg_getpwuid_r(uid_t uid, struct passwd *result,
}
// _nss_borg_getpwnam_r()
-// Find a user account by name
-
+// Called by NSS to find a user account by name
enum nss_status _nss_borg_getpwnam_r(const char *name, struct passwd *result,
- char *buffer, size_t buflen,
- int *errnop) {
-
+ char *buffer, size_t buflen, int *errnop) {
enum nss_status ret;
+ int non_borg_user = 0;
NSSBORG_LOCK;
ret = _nss_borg_setpwent_locked();
DEBUG("Looking for user %s\n", name);
if (ret == NSS_STATUS_SUCCESS) {
- while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop))
- == NSS_STATUS_SUCCESS) {
- if (!strcmp(result->pw_name, name))
+ while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop,
+ &non_borg_user)) ==
+ NSS_STATUS_SUCCESS) {
+ if (!strcmp(result->pw_name, name)) {
+ if (non_borg_user) {
+ WARN("Returning non borg user %d:%s in process: %s running as: %d\n",
+ result->pw_uid, result->pw_name, exec_name, getuid());
+ }
break;
+ }
}
}
^ permalink raw reply [flat|nested] 3+ messages in thread
* [glibc/maskray/grte] Update passwd.borg handling to use passwd.borg.real
@ 2021-08-27 23:45 Fangrui Song
0 siblings, 0 replies; 3+ messages in thread
From: Fangrui Song @ 2021-08-27 23:45 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=5f2404b6ed2feb66724b3737ac2aebfca4ac7592
commit 5f2404b6ed2feb66724b3737ac2aebfca4ac7592
Author: Stan Shebs <stanshebs@google.com>
Date: Fri Dec 20 13:58:35 2019 -0800
Update passwd.borg handling to use passwd.borg.real
Diff:
---
nss/nss_borg/borg-pwd.c | 215 ++++++++++++++++++++++++++++++++++--------------
1 file changed, 151 insertions(+), 64 deletions(-)
diff --git a/nss/nss_borg/borg-pwd.c b/nss/nss_borg/borg-pwd.c
index a0eb0e3954..2e50b287a9 100644
--- a/nss/nss_borg/borg-pwd.c
+++ b/nss/nss_borg/borg-pwd.c
@@ -2,58 +2,85 @@
// /etc/passwd.borg and /etc/passwd.borg.base
// passwd.borg.base is a subset of passwd.borg that is used as a fallback.
-#include <stdio.h>
-#include <pwd.h>
-#include <sys/types.h>
-#include <nss.h>
#include <errno.h>
+#include <nss.h>
+#include <pwd.h>
+#include <stdio.h>
#include <string.h>
+#include <sys/types.h>
+#include <syslog.h>
#include <libc-lock.h>
-__libc_lock_define_initialized (static, lock)
-#define NSSBORG_LOCK __libc_lock_lock (lock)
-#define NSSBORG_UNLOCK __libc_lock_unlock (lock);
+__libc_lock_define_initialized(static, lock)
+#define NSSBORG_LOCK __libc_lock_lock(lock)
+#define NSSBORG_UNLOCK __libc_lock_unlock(lock);
+
+#define EXEC_NAME_SIZE 4096
static FILE *f;
static FILE *fb;
-
+static bool fb_eof;
+static FILE *fbr;
+static bool fbr_eof;
+static char exec_name[EXEC_NAME_SIZE];
+
+// This library will log into syslog any attempt to fetch a username from
+// /etc/passwd.borg file, but only if /etc/passwd.borg.real file is present.
+// This module makes the user lookup in following order:
+// /etc/passwd.borg.real
+// /etc/passwd.borg.base
+// /etc/passwd.borg
+
+
+// non_borg_user_lookup_warn is supposed to prevent log spew from a single
+// process.
+static int non_borg_user_lookup_warn = 0;
+
+#define LOGNSS(priority, fmt, ...) \
+ do { \
+ openlog("nss_borg", LOG_PID, 0); \
+ syslog(LOG_USER | priority, fmt, ##__VA_ARGS__); \
+ closelog(); \
+ } while (0)
#define DEBUG(fmt, ...)
+#define WARN(fmt, ...) LOGNSS(LOG_WARNING, fmt, ##__VA_ARGS__)
// _nss_borg_setpwent_locked()
// Internal setup routine
-
static enum nss_status _nss_borg_setpwent_locked(void) {
-
+ int readlink_ret;
DEBUG("Opening passwd.borg\n");
f = fopen("/etc/passwd.borg", "r");
DEBUG("Opening passwd.borg.base\n");
fb = fopen("/etc/passwd.borg.base", "r");
+ fb_eof = false;
+
+ DEBUG("Opening passwd.borg.real\n");
+ fbr = fopen("/etc/passwd.borg.real", "r");
+ fbr_eof = false;
+
+ DEBUG("Reading /proc/self/exe");
+ // readlink does not append null-byte, so we reserve last byte for it.
+ readlink_ret = readlink("/proc/self/exe", exec_name,
+ sizeof(exec_name) - 1);
+ if (readlink_ret == -1) {
+ DEBUG("Failed to readlink /proc/self/exe error: %d", errno);
+ strncpy(exec_name, "__unknown__", sizeof(exec_name));
+ } else {
+ exec_name[readlink_ret] = '\0';
+ }
- if (f||fb) {
+ if (f || fb || fbr) {
return NSS_STATUS_SUCCESS;
} else {
return NSS_STATUS_UNAVAIL;
}
}
-// _nss_borg_setpwent()
-// Called by NSS to open the passwd file
-// Oddly, NSS passes a boolean saying whether to keep the database file open; ignore it
-
-enum nss_status _nss_borg_setpwent(int stayopen) {
- enum nss_status ret;
- NSSBORG_LOCK;
- ret = _nss_borg_setpwent_locked();
- NSSBORG_UNLOCK;
- return ret;
-}
-
// _nss_borg_endpwent_locked()
// Internal close routine
-
static enum nss_status _nss_borg_endpwent_locked(void) {
-
DEBUG("Closing passwd.borg\n");
if (f) {
fclose(f);
@@ -64,40 +91,62 @@ static enum nss_status _nss_borg_endpwent_locked(void) {
fclose(fb);
fb = NULL;
}
+ DEBUG("Closing passwd.borg.real\n");
+ if (fbr) {
+ fclose(fbr);
+ fbr = NULL;
+ }
return NSS_STATUS_SUCCESS;
}
-// _nss_borg_endpwent()
-// Called by NSS to close the passwd file
-
-enum nss_status _nss_borg_endpwent(void) {
- enum nss_status ret;
- NSSBORG_LOCK;
- ret = _nss_borg_endpwent_locked();
- NSSBORG_UNLOCK;
- return ret;
+// Called internally. It's a wrapper around fgetpwent_r that prevents from
+// multiple read calls once EOF was reached (b/72036184)
+static int _nss_borg_fgetpwent_r_eof(FILE *fp, struct passwd *pwbuf,
+ char *buf, size_t buflen,
+ struct passwd **pwbufp, bool *eof) {
+ if (*eof) {
+ *pwbufp = NULL;
+ return ENOENT;
+ } else {
+ int ret = fgetpwent_r(fp, pwbuf, buf, buflen, pwbufp);
+ if (ret == ENOENT) {
+ *eof = true;
+ }
+ return ret;
+ }
}
// _nss_borg_getpwent_r_locked()
// Called internally to return the next entry from the passwd file
-
static enum nss_status _nss_borg_getpwent_r_locked(struct passwd *result,
char *buffer, size_t buflen,
- int *errnop) {
-
+ int *errnop,
+ int *non_borg_user) {
enum nss_status ret;
// Save a copy of the buffer address, in case first call errors
// and sets it to 0.
struct passwd *sparecopy = result;
- if (
- f != NULL && (fgetpwent_r(f, result, buffer, buflen, &result) == 0)) {
- DEBUG("Returning borg user %d:%s\n", result->pw_uid, result->pw_name);
+ if (fbr != NULL && (_nss_borg_fgetpwent_r_eof(fbr, result, buffer, buflen,
+ &result, &fbr_eof) == 0)) {
+ DEBUG("Returning real borg user %d:%s\n", result->pw_uid, result->pw_name);
+ ret = NSS_STATUS_SUCCESS;
+ } else if (
+ // Yes, this is one of those cases where an assign makes sense.
+ fb != NULL && (result = sparecopy) &&
+ (_nss_borg_fgetpwent_r_eof(fb, result, buffer, buflen, &result,
+ &fb_eof) == 0)) {
+ DEBUG("Returning base borg user %d:%s\n", result->pw_uid, result->pw_name);
ret = NSS_STATUS_SUCCESS;
} else if (
- // Yes, this is one of those cases where an assign makes sense.
- // NB: passwd.borg.base is not ordered by UID as of cl/201005022.
- fb != NULL && (result = sparecopy) && (fgetpwent_r(fb, result, buffer, buflen, &result) == 0)) {
- DEBUG("Returning base user %d:%s\n", result->pw_uid, result->pw_name);
+ // Yes, this is one of those cases where an assign makes sense.
+ // NB: passwd.borg.base is not ordered by UID as of cl/201005022.
+ f != NULL && (result = sparecopy) &&
+ (fgetpwent_r(f, result, buffer, buflen, &result) == 0)) {
+ DEBUG("Returning non borg user %d:%s\n", result->pw_uid, result->pw_name);
+ // Log only if passwd.borg.real file is present.
+ if (fbr) {
+ *non_borg_user = 1;
+ }
ret = NSS_STATUS_SUCCESS;
} else {
*errnop = errno;
@@ -114,36 +163,70 @@ static enum nss_status _nss_borg_getpwent_r_locked(struct passwd *result,
return ret;
}
+// All methods below are public interface of this library.
+
+// _nss_borg_setpwent()
+// Called by NSS to open the passwd file
+// Oddly, NSS passes a boolean saying whether to keep the database file open;
+// ignore it
+enum nss_status _nss_borg_setpwent(int stayopen) {
+ enum nss_status ret;
+ NSSBORG_LOCK;
+ ret = _nss_borg_setpwent_locked();
+ NSSBORG_UNLOCK;
+ return ret;
+}
+
+// _nss_borg_endpwent()
+// Called by NSS to close the passwd file
+enum nss_status _nss_borg_endpwent(void) {
+ enum nss_status ret;
+ NSSBORG_LOCK;
+ ret = _nss_borg_endpwent_locked();
+ NSSBORG_UNLOCK;
+ return ret;
+}
+
// _nss_borg_getpwent_r()
// Called by NSS (I think) to look up next entry in passwd file
-enum nss_status _nss_borg_getpwent_r(struct passwd *result,
- char *buffer, size_t buflen,
- int *errnop) {
+enum nss_status _nss_borg_getpwent_r(struct passwd *result, char *buffer,
+ size_t buflen, int *errnop) {
enum nss_status ret;
+ int non_borg_user = 0;
NSSBORG_LOCK;
- ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop);
+ ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop,
+ &non_borg_user);
+ if (non_borg_user && !non_borg_user_lookup_warn) {
+ non_borg_user_lookup_warn = 1;
+ WARN("Reached non borg section in getpwent call "
+ "in process: %s running as: %d\n", exec_name, getuid());
+ }
NSSBORG_UNLOCK;
return ret;
}
// _nss_borg_getpwuid_r()
-// Find a user account by uid
-
+// Called by NSS to find a user account by uid
enum nss_status _nss_borg_getpwuid_r(uid_t uid, struct passwd *result,
- char *buffer, size_t buflen,
- int *errnop) {
-
+ char *buffer, size_t buflen, int *errnop) {
enum nss_status ret;
+ int non_borg_user = 0;
NSSBORG_LOCK;
ret = _nss_borg_setpwent_locked();
DEBUG("Looking for uid %d\n", uid);
if (ret == NSS_STATUS_SUCCESS) {
- while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop))
- == NSS_STATUS_SUCCESS) {
- if (result->pw_uid == uid)
+ while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop,
+ &non_borg_user)) ==
+ NSS_STATUS_SUCCESS) {
+ if (result->pw_uid == uid) {
+ if (non_borg_user) {
+ WARN("Returning non borg user %d:%s in process: %s running as: %d\n",
+ result->pw_uid, result->pw_name, exec_name, getuid());
+ }
break;
+ }
}
}
@@ -154,23 +237,27 @@ enum nss_status _nss_borg_getpwuid_r(uid_t uid, struct passwd *result,
}
// _nss_borg_getpwnam_r()
-// Find a user account by name
-
+// Called by NSS to find a user account by name
enum nss_status _nss_borg_getpwnam_r(const char *name, struct passwd *result,
- char *buffer, size_t buflen,
- int *errnop) {
-
+ char *buffer, size_t buflen, int *errnop) {
enum nss_status ret;
+ int non_borg_user = 0;
NSSBORG_LOCK;
ret = _nss_borg_setpwent_locked();
DEBUG("Looking for user %s\n", name);
if (ret == NSS_STATUS_SUCCESS) {
- while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop))
- == NSS_STATUS_SUCCESS) {
- if (!strcmp(result->pw_name, name))
+ while ((ret = _nss_borg_getpwent_r_locked(result, buffer, buflen, errnop,
+ &non_borg_user)) ==
+ NSS_STATUS_SUCCESS) {
+ if (!strcmp(result->pw_name, name)) {
+ if (non_borg_user) {
+ WARN("Returning non borg user %d:%s in process: %s running as: %d\n",
+ result->pw_uid, result->pw_name, exec_name, getuid());
+ }
break;
+ }
}
}
^ permalink raw reply [flat|nested] 3+ messages in thread
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