coredump: accept hostname on command line (#8033)

This commint adds a new command line parameter to sytemd-coredump. The
parameter should be mappend to core_pattern's placeholder %h - hostname.

The field _HOSTNAME holds the name from the kernel's namespaces which might be
different then the one comming from process' namespaces.

It is true that the real hostname is usually available in the field
COREDUMP_ENVIRON (environment variables) but I believe it is more reliable to
use the value passed by kernel.

----

The length of iovec is no longer static and hence I corrected the declarations
of the functions set_iovec_field and set_iovec_field_free.

Thank you @yuwata and @poettering!

1 files changed, 15 insertions, 6 deletions

diff --git a/src/coredump/coredump.c b/src/coredump/coredump.c
index fdcea22f56..6900af9fb5 100644
--- a/src/coredump/coredump.c
+++ b/src/coredump/coredump.c
@@ -102,6 +102,7 @@ enum {
         CONTEXT_SIGNAL,
         CONTEXT_TIMESTAMP,
         CONTEXT_RLIMIT,
+        CONTEXT_HOSTNAME,
         CONTEXT_COMM,
         CONTEXT_EXE,
         CONTEXT_UNIT,
@@ -205,6 +206,7 @@ static int fix_xattr(int fd, const char *context[_CONTEXT_MAX]) {
                 [CONTEXT_SIGNAL] = "user.coredump.signal",
                 [CONTEXT_TIMESTAMP] = "user.coredump.timestamp",
                 [CONTEXT_RLIMIT] = "user.coredump.rlimit",
+                [CONTEXT_HOSTNAME] = "user.coredump.hostname",
                 [CONTEXT_COMM] = "user.coredump.comm",
                 [CONTEXT_EXE] = "user.coredump.exe",
         };
@@ -848,6 +850,7 @@ static void map_context_fields(const struct iovec *iovec, const char* context[])
                 [CONTEXT_SIGNAL] = "COREDUMP_SIGNAL=",
                 [CONTEXT_TIMESTAMP] = "COREDUMP_TIMESTAMP=",
                 [CONTEXT_RLIMIT] = "COREDUMP_RLIMIT=",
+                [CONTEXT_HOSTNAME] = "COREDUMP_HOSTNAME=",
                 [CONTEXT_COMM] = "COREDUMP_COMM=",
                 [CONTEXT_EXE] = "COREDUMP_EXE=",
         };
@@ -981,6 +984,7 @@ static int process_socket(int fd) {
         assert(context[CONTEXT_SIGNAL]);
         assert(context[CONTEXT_TIMESTAMP]);
         assert(context[CONTEXT_RLIMIT]);
+        assert(context[CONTEXT_HOSTNAME]);
         assert(context[CONTEXT_COMM]);
         assert(coredump_fd >= 0);
 
@@ -1067,7 +1071,7 @@ static int send_iovec(const struct iovec iovec[], size_t n_iovec, int input_fd)
         return 0;
 }
 
-static char* set_iovec_field(struct iovec iovec[27], size_t *n_iovec, const char *field, const char *value) {
+static char* set_iovec_field(struct iovec *iovec, size_t *n_iovec, const char *field, const char *value) {
         char *x;
 
         x = strappend(field, value);
@@ -1076,7 +1080,7 @@ static char* set_iovec_field(struct iovec iovec[27], size_t *n_iovec, const char
         return x;
 }
 
-static char* set_iovec_field_free(struct iovec iovec[27], size_t *n_iovec, const char *field, char *value) {
+static char* set_iovec_field_free(struct iovec *iovec, size_t *n_iovec, const char *field, char *value) {
         char *x;
 
         x = set_iovec_field(iovec, n_iovec, field, value);
@@ -1089,7 +1093,7 @@ static int gather_pid_metadata(
                 char **comm_fallback,
                 struct iovec *iovec, size_t *n_iovec) {
 
-        /* We need 26 empty slots in iovec!
+        /* We need 27 empty slots in iovec!
          *
          * Note that if we fail on oom later on, we do not roll-back changes to the iovec structure. (It remains valid,
          * with the first n_iovec fields initialized.) */
@@ -1151,6 +1155,9 @@ static int gather_pid_metadata(
         if (!set_iovec_field(iovec, n_iovec, "COREDUMP_RLIMIT=", context[CONTEXT_RLIMIT]))
                 return log_oom();
 
+        if (!set_iovec_field(iovec, n_iovec, "COREDUMP_HOSTNAME=", context[CONTEXT_HOSTNAME]))
+                return log_oom();
+
         if (!set_iovec_field(iovec, n_iovec, "COREDUMP_COMM=", context[CONTEXT_COMM]))
                 return log_oom();
 
@@ -1231,7 +1238,7 @@ static int gather_pid_metadata(
 static int process_kernel(int argc, char* argv[]) {
 
         char* context[_CONTEXT_MAX] = {};
-        struct iovec iovec[28 + SUBMIT_COREDUMP_FIELDS];
+        struct iovec iovec[29 + SUBMIT_COREDUMP_FIELDS];
         size_t i, n_iovec, n_to_free = 0;
         int r;
 
@@ -1248,6 +1255,7 @@ static int process_kernel(int argc, char* argv[]) {
         context[CONTEXT_SIGNAL]    = argv[1 + CONTEXT_SIGNAL];
         context[CONTEXT_TIMESTAMP] = argv[1 + CONTEXT_TIMESTAMP];
         context[CONTEXT_RLIMIT]    = argv[1 + CONTEXT_RLIMIT];
+        context[CONTEXT_HOSTNAME]  = argv[1 + CONTEXT_HOSTNAME];
 
         r = gather_pid_metadata(context, argv + 1 + CONTEXT_COMM, iovec, &n_to_free);
         if (r < 0)
@@ -1304,9 +1312,10 @@ static int process_backtrace(int argc, char *argv[]) {
         context[CONTEXT_SIGNAL]    = argv[2 + CONTEXT_SIGNAL];
         context[CONTEXT_TIMESTAMP] = argv[2 + CONTEXT_TIMESTAMP];
         context[CONTEXT_RLIMIT]    = argv[2 + CONTEXT_RLIMIT];
+        context[CONTEXT_HOSTNAME]  = argv[2 + CONTEXT_HOSTNAME];
 
-        n_allocated = 33 + COREDUMP_STORAGE_EXTERNAL;
-        /* 25 metadata, 2 static, +unknown input, 4 storage, rounded up */
+        n_allocated = 34 + COREDUMP_STORAGE_EXTERNAL;
+        /* 26 metadata, 2 static, +unknown input, 4 storage, rounded up */
         iovec = new(struct iovec, n_allocated);
         if (!iovec)
                 return log_oom();