X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=lttng-sessiond%2Futils.c;h=1e08de77d4ca2854611c6a7372a769a9c7bdeb5e;hb=67f747d8095da3f240f71e33c4a1eb0f84aa5e41;hp=0da5642109fcc5ddf7eeced026a0d441cb685594;hpb=322585731ced1adba36cddcb8bdd5d997d1b2e3e;p=lttng-tools.git

diff --git a/lttng-sessiond/utils.c b/lttng-sessiond/utils.c
index 0da564210..1e08de77d 100644
--- a/lttng-sessiond/utils.c
+++ b/lttng-sessiond/utils.c
@@ -22,14 +22,27 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/wait.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <fcntl.h>
 
 #include <lttngerr.h>
 
 #include "utils.h"
 
+struct mkdir_data {
+	const char *path;
+	mode_t mode;
+};
+
+struct open_data {
+	const char *path;
+	int flags;
+	mode_t mode;
+};
+
 /*
  * Write to writable pipe used to notify a thread.
  */
@@ -58,12 +71,19 @@ const char *get_home_dir(void)
 /*
  * Create recursively directory using the FULL path.
  */
-int mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid)
+static
+int _mkdir_recursive(void *_data)
 {
-	int ret;
+	struct mkdir_data *data = _data;
+	const char *path;
 	char *p, tmp[PATH_MAX];
+	struct stat statbuf;
+	mode_t mode;
 	size_t len;
-	mode_t old_umask;
+	int ret;
+
+	path = data->path;
+	mode = data->mode;
 
 	ret = snprintf(tmp, sizeof(tmp), "%s", path);
 	if (ret < 0) {
@@ -76,27 +96,18 @@ int mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid)
 		tmp[len - 1] = 0;
 	}
 
-	old_umask = umask(0);
 	for (p = tmp + 1; *p; p++) {
 		if (*p == '/') {
 			*p = 0;
-			ret = mkdir(tmp, mode);
+			ret = stat(tmp, &statbuf);
 			if (ret < 0) {
-				if (!(errno == EEXIST)) {
-					PERROR("mkdir recursive");
-					ret = -errno;
-					goto umask_error;
-				}
-			} else if (ret == 0) {
-				/*
-				 * We created the directory. Set its ownership to the
-				 * user/group specified.
-				 */
-				ret = chown(tmp, uid, gid);
+				ret = mkdir(tmp, mode);
 				if (ret < 0) {
-					PERROR("chown in mkdir recursive");
-					ret = -errno;
-					goto umask_error;
+					if (!(errno == EEXIST)) {
+						PERROR("mkdir recursive");
+						ret = -errno;
+						goto error;
+					}
 				}
 			}
 			*p = '/';
@@ -111,21 +122,113 @@ int mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid)
 		} else {
 			ret = 0;
 		}
-	} else if (ret == 0) {
+	}
+
+error:
+	return ret;
+}
+
+static
+int _mkdir(void *_data)
+{
+	struct mkdir_data *data = _data;
+	return mkdir(data->path, data->mode);
+}
+
+static
+int _open(void *_data)
+{
+	struct open_data *data = _data;
+	return open(data->path, data->flags, data->mode);
+}
+
+static
+int run_as(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid)
+{
+	int ret = 0;
+	pid_t pid;
+
+	/*
+	 * If we are non-root, we can only deal with our own uid.
+	 */
+	if (geteuid() != 0) {
+		if (uid != geteuid()) {
+			ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)",
+				uid, geteuid());
+			return -EPERM;
+		}
+		return (*cmd)(data);
+	}
+
+	pid = fork();
+	if (pid > 0) {
+		int status;
+
 		/*
-		 * We created the directory. Set its ownership to the user/group
-		 * specified.
+		 * Parent: wait for child to return, in which case the
+		 * shared memory map will have been created.
 		 */
-		ret = chown(tmp, uid, gid);
+		pid = wait(&status);
+		if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+			ret = -1;
+			goto end;
+		}
+		goto end;
+	} else if (pid == 0) {
+		/* Child */
+		setegid(gid);
 		if (ret < 0) {
-			PERROR("chown in mkdir recursive");
-			ret = -errno;
-			goto umask_error;
+			perror("setegid");
+			exit(EXIT_FAILURE);
 		}
+		ret = seteuid(uid);
+		if (ret < 0) {
+			perror("seteuid");
+			exit(EXIT_FAILURE);
+		}
+		umask(0);
+		ret = (*cmd)(data);
+		if (!ret)
+			exit(EXIT_SUCCESS);
+		else
+			exit(EXIT_FAILURE);
+	} else {
+		return -1;
 	}
-
-umask_error:
-	umask(old_umask);
-error:
+end:
 	return ret;
 }
+
+int mkdir_recursive_run_as(const char *path, mode_t mode, uid_t uid, gid_t gid)
+{
+	struct mkdir_data data;
+
+	DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d",
+			path, mode, uid, gid);
+	data.path = path;
+	data.mode = mode;
+	return run_as(_mkdir_recursive, &data, uid, gid);
+}
+
+int mkdir_run_as(const char *path, mode_t mode, uid_t uid, gid_t gid)
+{
+	struct mkdir_data data;
+
+	DBG3("mkdir() %s with mode %d for uid %d and gid %d",
+			path, mode, uid, gid);
+	data.path = path;
+	data.mode = mode;
+	return run_as(_mkdir, &data, uid, gid);
+}
+
+int open_run_as(const char *path, int flags, mode_t mode, uid_t uid, gid_t gid)
+{
+	struct open_data data;
+
+	DBG3("open() %s with flags %d mode %d for uid %d and gid %d",
+			path, flags, mode, uid, gid);
+	data.path = path;
+	data.flags = flags;
+	data.mode = mode;
+	return run_as(_open, &data, uid, gid);
+}