Merge pull request #7846 from poettering/nobody-getenv

some assorted fixes and additions, in particular a way to turn off "nobody" synthesizing on a specific system

src/basic/fileio.c

@@ -1225,8 +1225,7 @@ int tempfn_xxxxxx(const char *p, const char *extra, char **ret) {
         if (!filename_is_valid(fn))
                 return -EINVAL;
 
-        if (!extra)
-                extra = "";
+        extra = strempty(extra);
 
         t = new(char, strlen(p) + 2 + strlen(extra) + 6 + 1);
         if (!t)
@@ -1259,8 +1258,7 @@ int tempfn_random(const char *p, const char *extra, char **ret) {
         if (!filename_is_valid(fn))
                 return -EINVAL;
 
-        if (!extra)
-                extra = "";
+        extra = strempty(extra);
 
         t = new(char, strlen(p) + 2 + strlen(extra) + 16 + 1);
         if (!t)
@@ -1300,8 +1298,7 @@ int tempfn_random_child(const char *p, const char *extra, char **ret) {
                         return r;
         }
 
-        if (!extra)
-                extra = "";
+        extra = strempty(extra);
 
         t = new(char, strlen(p) + 3 + strlen(extra) + 16 + 1);
         if (!t)

src/basic/fs-util.h

@@ -29,6 +29,7 @@
 #include <unistd.h>
 
 #include "time-util.h"
+#include "util.h"
 
 int unlink_noerrno(const char *path);
 
@@ -89,13 +90,14 @@ int chase_symlinks(const char *path_with_prefix, const char *root, unsigned flag
 
 /* Useful for usage with _cleanup_(), removes a directory and frees the pointer */
 static inline void rmdir_and_free(char *p) {
+        PROTECT_ERRNO;
         (void) rmdir(p);
         free(p);
 }
 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, rmdir_and_free);
 
 static inline void unlink_and_free(char *p) {
-        (void) unlink(p);
+        (void) unlink_noerrno(p);
         free(p);
 }
 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, unlink_and_free);

src/basic/process-util.c

@@ -796,6 +796,8 @@ void sigkill_wait(pid_t pid) {
 }
 
 void sigkill_waitp(pid_t *pid) {
+        PROTECT_ERRNO;
+
         if (!pid)
                 return;
         if (*pid <= 1)

src/basic/rm-rf.h

@@ -22,6 +22,8 @@
 
 #include <sys/stat.h>
 
+#include "util.h"
+
 typedef enum RemoveFlags {
         REMOVE_ONLY_DIRECTORIES = 1,
         REMOVE_ROOT = 2,
@@ -34,6 +36,7 @@ int rm_rf(const char *path, RemoveFlags flags);
 
 /* Useful for usage with _cleanup_(), destroys a directory and frees the pointer */
 static inline void rm_rf_physical_and_free(char *p) {
+        PROTECT_ERRNO;
         (void) rm_rf(p, REMOVE_ROOT|REMOVE_PHYSICAL);
         free(p);
 }

src/basic/string-util.h

@@ -52,15 +52,15 @@ static inline bool streq_ptr(const char *a, const char *b) {
 }
 
 static inline const char* strempty(const char *s) {
-        return s ? s : "";
+        return s ?: "";
 }
 
 static inline const char* strnull(const char *s) {
-        return s ? s : "(null)";
+        return s ?: "(null)";
 }
 
 static inline const char *strna(const char *s) {
-        return s ? s : "n/a";
+        return s ?: "n/a";
 }
 
 static inline bool isempty(const char *p) {

src/basic/user-util.c

@@ -137,7 +137,8 @@ int get_user_creds(
                 return 0;
         }
 
-        if (STR_IN_SET(*username, NOBODY_USER_NAME, "65534")) {
+        if (synthesize_nobody() &&
+            STR_IN_SET(*username, NOBODY_USER_NAME, "65534")) {
                 *username = NOBODY_USER_NAME;
 
                 if (uid)
@@ -243,7 +244,8 @@ int get_group_creds(const char **groupname, gid_t *gid) {
                 return 0;
         }
 
-        if (STR_IN_SET(*groupname, NOBODY_GROUP_NAME, "65534")) {
+        if (synthesize_nobody() &&
+            STR_IN_SET(*groupname, NOBODY_GROUP_NAME, "65534")) {
                 *groupname = NOBODY_GROUP_NAME;
 
                 if (gid)
@@ -283,7 +285,8 @@ char* uid_to_name(uid_t uid) {
         /* Shortcut things to avoid NSS lookups */
         if (uid == 0)
                 return strdup("root");
-        if (uid == UID_NOBODY)
+        if (synthesize_nobody() &&
+            uid == UID_NOBODY)
                 return strdup(NOBODY_USER_NAME);
 
         if (uid_is_valid(uid)) {
@@ -323,7 +326,8 @@ char* gid_to_name(gid_t gid) {
 
         if (gid == 0)
                 return strdup("root");
-        if (gid == GID_NOBODY)
+        if (synthesize_nobody() &&
+            gid == GID_NOBODY)
                 return strdup(NOBODY_GROUP_NAME);
 
         if (gid_is_valid(gid)) {
@@ -427,7 +431,8 @@ int get_home_dir(char **_h) {
                 *_h = h;
                 return 0;
         }
-        if (u == UID_NOBODY) {
+        if (synthesize_nobody() &&
+            u == UID_NOBODY) {
                 h = strdup("/");
                 if (!h)
                         return -ENOMEM;
@@ -482,7 +487,8 @@ int get_shell(char **_s) {
                 *_s = s;
                 return 0;
         }
-        if (u == UID_NOBODY) {
+        if (synthesize_nobody() &&
+            u == UID_NOBODY) {
                 s = strdup("/sbin/nologin");
                 if (!s)
                         return -ENOMEM;
@@ -690,3 +696,24 @@ int maybe_setgroups(size_t size, const gid_t *list) {
 
         return 0;
 }
+
+bool synthesize_nobody(void) {
+
+#ifdef NOLEGACY
+        return true;
+#else
+        /* Returns true when we shall synthesize the "nobody" user (which we do by default). This can be turned off by
+         * touching /etc/systemd/dont-synthesize-nobody in order to provide upgrade compatibility with legacy systems
+         * that used the "nobody" user name and group name for other UIDs/GIDs than 65534.
+         *
+         * Note that we do not employ any kind of synchronization on the following caching variable. If the variable is
+         * accessed in multi-threaded programs in the worst case it might happen that we initialize twice, but that
+         * shouldn't matter as each initialization should come to the same result. */
+        static int cache = -1;
+
+        if (cache < 0)
+                cache = access("/etc/systemd/dont-synthesize-nobody", F_OK) < 0;
+
+        return cache;
+#endif
+}

src/basic/user-util.h

@@ -97,3 +97,5 @@ bool valid_gecos(const char *d);
 bool valid_home(const char *p);
 
 int maybe_setgroups(size_t size, const gid_t *list);
+
+bool synthesize_nobody(void);

src/basic/util.c

@@ -618,7 +618,13 @@ int str_verscmp(const char *s1, const char *s2) {
 }
 
 /* Turn off core dumps but only if we're running outside of a container. */
-void disable_core_dumps(void) {
-        if (detect_container() <= 0)
-                (void) write_string_file("/proc/sys/kernel/core_pattern", "|/bin/false", 0);
+void disable_coredumps(void) {
+        int r;
+
+        if (detect_container() > 0)
+                return;
+
+        r = write_string_file("/proc/sys/kernel/core_pattern", "|/bin/false", 0);
+        if (r < 0)
+                log_debug_errno(r, "Failed to turn off coredumps, ignoring: %m");
 }

src/basic/util.h

@@ -192,4 +192,4 @@ int version(void);
 
 int str_verscmp(const char *s1, const char *s2);
 
-void disable_core_dumps(void);
+void disable_coredumps(void);