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From e9bef2f8146ccf152459248775eec8e8ce123865 Mon Sep 17 00:00:00 2001
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From: Lennart Poettering <lennart@poettering.net>
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Date: Wed, 22 Apr 2015 22:54:23 +0200
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Subject: [PATCH] journalctl: rework code that checks whether we have access to
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 /var/log/journal
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- fix some memory leaks on error conditions
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- handle all error cases properly, and log about failures
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- move HAVE_ACL and no-HAVE_ACL code closer to each other
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Cherry-picked from: e346512c684e9efae84c6442f7e6a5781564ecde
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Related: #1318994
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---
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 src/journal/journalctl.c | 120 ++++++++++++++++++++++++-----------------------
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 src/shared/acl-util.c    | 102 ++++++++++++++++++++++------------------
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 src/shared/acl-util.h    |   2 +-
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 3 files changed, 119 insertions(+), 105 deletions(-)
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diff --git a/src/journal/journalctl.c b/src/journal/journalctl.c
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index 6ba884779..f60e6415f 100644
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--- a/src/journal/journalctl.c
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+++ b/src/journal/journalctl.c
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@@ -1680,61 +1680,76 @@ static int verify(sd_journal *j) {
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         return r;
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 }
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-#ifdef HAVE_ACL
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 static int access_check_var_log_journal(sd_journal *j) {
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+#ifdef HAVE_ACL
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         _cleanup_strv_free_ char **g = NULL;
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-        bool have_access;
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+        const char* dir;
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+#endif
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         int r;
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         assert(j);
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-        have_access = in_group("systemd-journal") > 0;
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+        if (arg_quiet)
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+                return 0;
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-        if (!have_access) {
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-                const char* dir;
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+        /* If we are root, we should have access, don't warn. */
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+        if (getuid() == 0)
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+                return 0;
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-                if (access("/run/log/journal", F_OK) >= 0)
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-                        dir = "/run/log/journal";
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-                else
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-                        dir = "/var/log/journal";
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+        /* If we are in the 'systemd-journal' group, we should have
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+         * access too. */
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+        r = in_group("systemd-journal");
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+        if (r < 0)
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+                return log_error_errno(r, "Failed to check if we are in the 'systemd-journal' group: %m");
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+        if (r > 0)
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+                return 0;
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-                /* Let's enumerate all groups from the default ACL of
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-                 * the directory, which generally should allow access
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-                 * to most journal files too */
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-                r = search_acl_groups(&g, dir, &have_access);
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-                if (r < 0)
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-                        return r;
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-        }
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+#ifdef HAVE_ACL
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+        if (laccess("/run/log/journal", F_OK) >= 0)
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+                dir = "/run/log/journal";
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+        else
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+                dir = "/var/log/journal";
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-        if (!have_access) {
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+        /* If we are in any of the groups listed in the journal ACLs,
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+         * then all is good, too. Let's enumerate all groups from the
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+         * default ACL of the directory, which generally should allow
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+         * access to most journal files too. */
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+        r = acl_search_groups(dir, &g);
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+        if (r < 0)
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+                return log_error_errno(r, "Failed to search journal ACL: %m");
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+        if (r > 0)
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+                return 0;
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-                if (strv_isempty(g))
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-                        log_notice("Hint: You are currently not seeing messages from other users and the system.\n"
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-                                   "      Users in the 'systemd-journal' group can see all messages. Pass -q to\n"
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-                                   "      turn off this notice.");
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-                else {
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-                        _cleanup_free_ char *s = NULL;
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+        /* Print a pretty list, if there were ACLs set. */
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+        if (!strv_isempty(g)) {
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+                _cleanup_free_ char *s = NULL;
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-                        r = strv_extend(&g, "systemd-journal");
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-                        if (r < 0)
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-                                return log_oom();
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+                /* Thre are groups in the ACL, let's list them */
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+                r = strv_extend(&g, "systemd-journal");
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+                if (r < 0)
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+                        return log_oom();
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-                        strv_sort(g);
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-                        strv_uniq(g);
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+                strv_sort(g);
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+                strv_uniq(g);
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-                        s = strv_join(g, "', '");
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-                        if (!s)
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-                                return log_oom();
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+                s = strv_join(g, "', '");
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+                if (!s)
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+                        return log_oom();
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-                        log_notice("Hint: You are currently not seeing messages from other users and the system.\n"
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-                                   "      Users in groups '%s' can see all messages.\n"
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-                                   "      Pass -q to turn off this notice.", s);
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-                }
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+                log_notice("Hint: You are currently not seeing messages from other users and the system.\n"
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+                           "      Users in groups '%s' can see all messages.\n"
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+                           "      Pass -q to turn off this notice.", s);
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+                return 1;
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         }
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+#endif
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-        return 0;
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+        /* If no ACLs were found, print a short version of the message. */
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+        log_notice("Hint: You are currently not seeing messages from other users and the system.\n"
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+                   "      Users in the 'systemd-journal' group can see all messages. Pass -q to\n"
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+                   "      turn off this notice.");
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+
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+        return 1;
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 }
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-#endif
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 static int access_check(sd_journal *j) {
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         Iterator it;
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@@ -1746,30 +1761,15 @@ static int access_check(sd_journal *j) {
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         if (set_isempty(j->errors)) {
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                 if (ordered_hashmap_isempty(j->files))
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                         log_notice("No journal files were found.");
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+
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                 return 0;
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         }
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         if (set_contains(j->errors, INT_TO_PTR(-EACCES))) {
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-#ifdef HAVE_ACL
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-                /* If /run/log/journal or /var/log/journal exist, try
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-                   to pring a nice notice if the user lacks access to it. */
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-                if (!arg_quiet && geteuid() != 0) {
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-                        r = access_check_var_log_journal(j);
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-                        if (r < 0)
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-                                return r;
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-                }
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-#else
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-                if (geteuid() != 0 && in_group("systemd-journal") <= 0) {
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-                        log_error("Unprivileged users cannot access messages. Users in the 'systemd-journal' group\n"
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-                                  "group may access messages.");
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-                        return -EACCES;
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-                }
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-#endif
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+                (void) access_check_var_log_journal(j);
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-                if (ordered_hashmap_isempty(j->files)) {
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-                        log_error("No journal files were opened due to insufficient permissions.");
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-                        r = -EACCES;
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-                }
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+                if (ordered_hashmap_isempty(j->files))
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+                        r = log_error_errno(EACCES, "No journal files were opened due to insufficient permissions.");
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         }
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         SET_FOREACH(code, j->errors, it) {
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@@ -1778,8 +1778,12 @@ static int access_check(sd_journal *j) {
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                 err = -PTR_TO_INT(code);
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                 assert(err > 0);
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-                if (err != EACCES)
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-                        log_warning_errno(err, "Error was encountered while opening journal files: %m");
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+                if (err == EACCES)
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+                        continue;
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+
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+                log_warning_errno(err, "Error was encountered while opening journal files: %m");
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+                if (r == 0)
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+                        r = -err;
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         }
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         return r;
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diff --git a/src/shared/acl-util.c b/src/shared/acl-util.c
181b3f
index e67e9acb6..d18a02f50 100644
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--- a/src/shared/acl-util.c
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+++ b/src/shared/acl-util.c
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@@ -82,17 +82,18 @@ int calc_acl_mask_if_needed(acl_t *acl_p) {
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                 if (tag == ACL_MASK)
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                         return 0;
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-                if (IN_SET(tag, ACL_USER, ACL_GROUP))
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-                        goto calc;
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+
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+                if (IN_SET(tag, ACL_USER, ACL_GROUP)) {
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+                        if (acl_calc_mask(acl_p) < 0)
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+                                return -errno;
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+
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+                        return 1;
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+                }
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         }
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         if (r < 0)
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                 return -errno;
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-        return 0;
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-calc:
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-        if (acl_calc_mask(acl_p) < 0)
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-                return -errno;
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-        return 1;
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+        return 0;
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 }
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 int add_base_acls_if_needed(acl_t *acl_p, const char *path) {
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@@ -159,59 +160,68 @@ int add_base_acls_if_needed(acl_t *acl_p, const char *path) {
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         return 0;
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 }
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-int search_acl_groups(char*** dst, const char* path, bool* belong) {
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-        acl_t acl;
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+int acl_search_groups(const char *path, char ***ret_groups) {
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+        _cleanup_strv_free_ char **g = NULL;
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+        _cleanup_(acl_free) acl_t acl = NULL;
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+        bool ret = false;
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+        acl_entry_t entry;
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+        int r;
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         assert(path);
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-        assert(belong);
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         acl = acl_get_file(path, ACL_TYPE_DEFAULT);
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-        if (acl) {
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-                acl_entry_t entry;
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-                int r;
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-
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-                r = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
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-                while (r > 0) {
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-                        acl_tag_t tag;
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-                        gid_t *gid;
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-                        char *name;
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+        if (!acl)
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+                return -errno;
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-                        r = acl_get_tag_type(entry, &tag;;
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-                        if (r < 0)
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-                                break;
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+        r = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
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+        for (;;) {
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+                _cleanup_(acl_free_gid_tpp) gid_t *gid = NULL;
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+                acl_tag_t tag;
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+
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+                if (r < 0)
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+                        return -errno;
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+                if (r == 0)
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+                        break;
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+
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+                if (acl_get_tag_type(entry, &tag) < 0)
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+                        return -errno;
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-                        if (tag != ACL_GROUP)
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-                                goto next;
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+                if (tag != ACL_GROUP)
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+                        goto next;
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-                        gid = acl_get_qualifier(entry);
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-                        if (!gid)
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-                                break;
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+                gid = acl_get_qualifier(entry);
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+                if (!gid)
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+                        return -errno;
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+
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+                if (in_gid(*gid) > 0) {
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+                        if (!ret_groups)
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+                                return true;
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-                        if (in_gid(*gid) > 0) {
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-                                *belong = true;
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-                                break;
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-                        }
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+                        ret = true;
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+                }
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+
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+                if (ret_groups) {
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+                        char *name;
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                         name = gid_to_name(*gid);
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-                        if (!name) {
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-                                acl_free(acl);
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-                                return log_oom();
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-                        }
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-
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-                        r = strv_consume(dst, name);
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-                        if (r < 0) {
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-                                acl_free(acl);
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-                                return log_oom();
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-                        }
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-
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-                next:
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-                        r = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry);
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+                        if (!name)
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+                                return -ENOMEM;
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+
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+                        r = strv_consume(&g, name);
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+                        if (r < 0)
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+                                return r;
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                 }
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-                acl_free(acl);
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+        next:
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+                r = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry);
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         }
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-        return 0;
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+        if (ret_groups) {
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+                *ret_groups = g;
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+                g = NULL;
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+        }
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+
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+        return ret;
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 }
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 int parse_acl(char *text, acl_t *acl_access, acl_t *acl_default, bool want_mask) {
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diff --git a/src/shared/acl-util.h b/src/shared/acl-util.h
181b3f
index fdb90063f..c8bcc266d 100644
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--- a/src/shared/acl-util.h
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+++ b/src/shared/acl-util.h
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@@ -32,7 +32,7 @@
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 int acl_find_uid(acl_t acl, uid_t uid, acl_entry_t *entry);
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 int calc_acl_mask_if_needed(acl_t *acl_p);
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 int add_base_acls_if_needed(acl_t *acl_p, const char *path);
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-int search_acl_groups(char*** dst, const char* path, bool* belong);
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+int acl_search_groups(const char* path, char ***ret_groups);
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 int parse_acl(char *text, acl_t *acl_access, acl_t *acl_default, bool want_mask);
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 int acls_for_file(const char *path, acl_type_t type, acl_t new, acl_t *acl);
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