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-rw-r--r--src/basic/user-util.c173
-rw-r--r--src/basic/user-util.h11
2 files changed, 113 insertions, 71 deletions
diff --git a/src/basic/user-util.c b/src/basic/user-util.c
index a562a397c7..b6185597de 100644
--- a/src/basic/user-util.c
+++ b/src/basic/user-util.c
@@ -87,17 +87,31 @@ char *getusername_malloc(void) {
return uid_to_name(getuid());
}
-int get_user_creds(
+static inline bool is_nologin_shell(const char *shell) {
+
+ return PATH_IN_SET(shell,
+ /* 'nologin' is the friendliest way to disable logins for a user account. It prints a nice
+ * message and exits. Different distributions place the binary at different places though,
+ * hence let's list them all. */
+ "/bin/nologin",
+ "/sbin/nologin",
+ "/usr/bin/nologin",
+ "/usr/sbin/nologin",
+ /* 'true' and 'false' work too for the same purpose, but are less friendly as they don't do
+ * any message printing. Different distributions place the binary at various places but at
+ * least not in the 'sbin' directory. */
+ "/bin/false",
+ "/usr/bin/false",
+ "/bin/true",
+ "/usr/bin/true");
+}
+
+static int synthesize_user_creds(
const char **username,
uid_t *uid, gid_t *gid,
const char **home,
- const char **shell) {
-
- struct passwd *p;
- uid_t u;
-
- assert(username);
- assert(*username);
+ const char **shell,
+ UserCredsFlags flags) {
/* We enforce some special rules for uid=0 and uid=65534: in order to avoid NSS lookups for root we hardcode
* their user record data. */
@@ -129,32 +143,85 @@ int get_user_creds(
*gid = GID_NOBODY;
if (home)
- *home = "/";
+ *home = FLAGS_SET(flags, USER_CREDS_CLEAN) ? NULL : "/";
if (shell)
- *shell = "/sbin/nologin";
+ *shell = FLAGS_SET(flags, USER_CREDS_CLEAN) ? NULL : "/sbin/nologin";
return 0;
}
+ return -ENOMEDIUM;
+}
+
+int get_user_creds(
+ const char **username,
+ uid_t *uid, gid_t *gid,
+ const char **home,
+ const char **shell,
+ UserCredsFlags flags) {
+
+ uid_t u = UID_INVALID;
+ struct passwd *p;
+ int r;
+
+ assert(username);
+ assert(*username);
+
+ if (!FLAGS_SET(flags, USER_CREDS_SYNTHESIZE_FALLBACK) ||
+ (!home && !shell)) {
+
+ /* So here's the deal: normally, we'll try to synthesize all records we can synthesize, and override
+ * the user database with that. However, if the user specifies USER_CREDS_SYNTHESIZE_FALLBACK then the
+ * user database will override the synthetic records instead — except if the user is only interested in
+ * the UID and/or GID (but not the home directory, or the shell), in which case we'll always override
+ * the user database (i.e. the USER_CREDS_SYNTHESIZE_FALLBACK flag has no effect in this case). Why?
+ * Simply because there are valid usecase where the user might change the home directory or the shell
+ * of the relevant users, but changing the UID/GID mappings for them is something we explicitly don't
+ * support. */
+
+ r = synthesize_user_creds(username, uid, gid, home, shell, flags);
+ if (r >= 0)
+ return 0;
+ if (r != -ENOMEDIUM) /* not a username we can synthesize */
+ return r;
+ }
+
if (parse_uid(*username, &u) >= 0) {
errno = 0;
p = getpwuid(u);
- /* If there are multiple users with the same id, make
- * sure to leave $USER to the configured value instead
- * of the first occurrence in the database. However if
- * the uid was configured by a numeric uid, then let's
- * pick the real username from /etc/passwd. */
+ /* If there are multiple users with the same id, make sure to leave $USER to the configured value
+ * instead of the first occurrence in the database. However if the uid was configured by a numeric uid,
+ * then let's pick the real username from /etc/passwd. */
if (p)
*username = p->pw_name;
+ else if (FLAGS_SET(flags, USER_CREDS_ALLOW_MISSING) && !gid && !home && !shell) {
+
+ /* If the specified user is a numeric UID and it isn't in the user database, and the caller
+ * passed USER_CREDS_ALLOW_MISSING and was only interested in the UID, then juts return that
+ * and don't complain. */
+
+ if (uid)
+ *uid = u;
+
+ return 0;
+ }
} else {
errno = 0;
p = getpwnam(*username);
}
+ if (!p) {
+ r = errno > 0 ? -errno : -ESRCH;
- if (!p)
- return errno > 0 ? -errno : -ESRCH;
+ /* If the user requested that we only synthesize as fallback, do so now */
+ if (FLAGS_SET(flags, USER_CREDS_SYNTHESIZE_FALLBACK)) {
+ if (synthesize_user_creds(username, uid, gid, home, shell, flags) >= 0)
+ return 0;
+ }
+
+ return r;
+ }
if (uid) {
if (!uid_is_valid(p->pw_uid))
@@ -170,66 +237,30 @@ int get_user_creds(
*gid = p->pw_gid;
}
- if (home)
- *home = p->pw_dir;
-
- if (shell)
- *shell = p->pw_shell;
-
- return 0;
-}
-
-static inline bool is_nologin_shell(const char *shell) {
-
- return PATH_IN_SET(shell,
- /* 'nologin' is the friendliest way to disable logins for a user account. It prints a nice
- * message and exits. Different distributions place the binary at different places though,
- * hence let's list them all. */
- "/bin/nologin",
- "/sbin/nologin",
- "/usr/bin/nologin",
- "/usr/sbin/nologin",
- /* 'true' and 'false' work too for the same purpose, but are less friendly as they don't do
- * any message printing. Different distributions place the binary at various places but at
- * least not in the 'sbin' directory. */
- "/bin/false",
- "/usr/bin/false",
- "/bin/true",
- "/usr/bin/true");
-}
-
-int get_user_creds_clean(
- const char **username,
- uid_t *uid, gid_t *gid,
- const char **home,
- const char **shell) {
-
- int r;
-
- /* Like get_user_creds(), but resets home/shell to NULL if they don't contain anything relevant. */
-
- r = get_user_creds(username, uid, gid, home, shell);
- if (r < 0)
- return r;
-
- if (shell &&
- (isempty(*shell) || is_nologin_shell(*shell)))
- *shell = NULL;
+ if (home) {
+ if (FLAGS_SET(flags, USER_CREDS_CLEAN) && empty_or_root(p->pw_dir))
+ *home = NULL;
+ else
+ *home = p->pw_dir;
+ }
- if (home && empty_or_root(*home))
- *home = NULL;
+ if (shell) {
+ if (FLAGS_SET(flags, USER_CREDS_CLEAN) && (isempty(p->pw_shell) || is_nologin_shell(p->pw_shell)))
+ *shell = NULL;
+ else
+ *shell = p->pw_shell;
+ }
return 0;
}
-int get_group_creds(const char **groupname, gid_t *gid) {
+int get_group_creds(const char **groupname, gid_t *gid, UserCredsFlags flags) {
struct group *g;
gid_t id;
assert(groupname);
- /* We enforce some special rules for gid=0: in order to avoid
- * NSS lookups for root we hardcode its data. */
+ /* We enforce some special rules for gid=0: in order to avoid NSS lookups for root we hardcode its data. */
if (STR_IN_SET(*groupname, "root", "0")) {
*groupname = "root";
@@ -256,6 +287,12 @@ int get_group_creds(const char **groupname, gid_t *gid) {
if (g)
*groupname = g->gr_name;
+ else if (FLAGS_SET(flags, USER_CREDS_ALLOW_MISSING)) {
+ if (gid)
+ *gid = id;
+
+ return 0;
+ }
} else {
errno = 0;
g = getgrnam(*groupname);
@@ -391,7 +428,7 @@ int in_group(const char *name) {
int r;
gid_t gid;
- r = get_group_creds(&name, &gid);
+ r = get_group_creds(&name, &gid, 0);
if (r < 0)
return r;
diff --git a/src/basic/user-util.h b/src/basic/user-util.h
index b2f198c89b..a18f4d6f1a 100644
--- a/src/basic/user-util.h
+++ b/src/basic/user-util.h
@@ -25,9 +25,14 @@ static inline int parse_gid(const char *s, gid_t *ret_gid) {
char* getlogname_malloc(void);
char* getusername_malloc(void);
-int get_user_creds(const char **username, uid_t *uid, gid_t *gid, const char **home, const char **shell);
-int get_user_creds_clean(const char **username, uid_t *uid, gid_t *gid, const char **home, const char **shell);
-int get_group_creds(const char **groupname, gid_t *gid);
+typedef enum UserCredsFlags {
+ USER_CREDS_SYNTHESIZE_FALLBACK = 1 << 0, /* if set, only synthesize user records if database lacks them. Normally we bypass the userdb entirely for the records we can synthesize */
+ USER_CREDS_ALLOW_MISSING = 1 << 1, /* if a numeric UID string is resolved, be OK if there's no record for it */
+ USER_CREDS_CLEAN = 1 << 2, /* try to clean up shell and home fields with invalid data */
+} UserCredsFlags;
+
+int get_user_creds(const char **username, uid_t *uid, gid_t *gid, const char **home, const char **shell, UserCredsFlags flags);
+int get_group_creds(const char **groupname, gid_t *gid, UserCredsFlags flags);
char* uid_to_name(uid_t uid);
char* gid_to_name(gid_t gid);
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-13 08:59:06 +0000