diff options
| -rw-r--r-- | Makefile | 5 | ||||
| -rw-r--r-- | src/config.h | 44 | ||||
| -rw-r--r-- | src/mds.c | 88 | ||||
| -rw-r--r-- | src/mds.h | 31 |
4 files changed, 152 insertions, 16 deletions
@@ -64,14 +64,15 @@ C_FLAGS = $(OPTIMISE) $(WARN) -std=$(STD) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) \ .PHONY: all all: bin/mds + bin/mds: obj/mds.o mkdir -p bin gcc $(C_FLAGS) -o $@ $^ -obj/mds.o: src/mds.c +obj/%.o: src/%.c src/*.h mkdir -p obj - gcc $(C_FLAGS) -c -o $@ $^ + gcc $(C_FLAGS) -c -o $@ $< diff --git a/src/config.h b/src/config.h index e3a8bb0..261b96e 100644 --- a/src/config.h +++ b/src/config.h @@ -23,7 +23,7 @@ * The root directory of all runtime data stored by MDS */ #ifndef MDS_RUNTIME_ROOT_DIRECTORY -#define MDS_RUNTIME_ROOT_DIRECTORY "/run/mds" +#define MDS_RUNTIME_ROOT_DIRECTORY "/run/mds" #endif @@ -35,5 +35,47 @@ #endif +/** + * The group ID for the root group + */ +#ifndef ROOT_GROUP_GID +#define ROOT_GROUP_GID 0 +#endif + +/* There two names above are redundant, but hat is to avoid errors. */ + + +/** + * The byte length of the authentication token + */ +#ifndef TOKEN_LENGTH +#define TOKEN_LENGTH 1024 +#endif + + +/** + * Random number generator to use for generating a token + */ +#ifndef TOKEN_RANDOM +#define TOKEN_RANDOM "/dev/urandom" +#endif + + +/** + * The maximum number of command line arguments to allow + */ +#ifndef ARGC_LIMIT +#define ARGC_LIMIT 50 +#endif + + +/** + * The maximum number of display allowed on the system + */ +#ifndef DISPLAY_MAX +#define DISPLAY_MAX 1000 +#endif + + #endif @@ -15,6 +15,7 @@ * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ +#include "mds.h" #include "config.h" #include <sys/stat.h> @@ -22,6 +23,8 @@ #include <stdio.h> #include <unistd.h> #include <errno.h> +#include <limits.h> +#include <fcntl.h> /** @@ -33,12 +36,15 @@ */ int main(int argc, const char** argv) { - struct stat attr; + char pathname[PATH_MAX]; + unsigned int display; + FILE *f; + int fd; (void) argv; /* Sanity check the number of command line arguments. */ - if (argc > 50) + if (argc > ARGC_LIMIT) { fprintf(stderr, "%s: that number of arguments is ridiculous, I will not allow it.\n", @@ -56,6 +62,58 @@ int main(int argc, const char** argv) } /* Create directory for socket files, PID files and such. */ + if (create_runtime_root_directory()) + return 1; + + /* Determine display index. */ + for (display = 0; display < DISPLAY_MAX; display++) + { + snprintf(pathname, sizeof(pathname) / sizeof(char), "%s/%u.pid", + MDS_RUNTIME_ROOT_DIRECTORY, display); + + fd = open(pathname, O_CREAT | O_EXCL); + if (fd == -1) + { + /* TODO reuse display index not no longer used */ + continue; + } + + close(fd); + } + if (display == DISPLAY_MAX) + { + fprintf(stderr, + "%s: Sorry, too many displays on the system.\n", + *argv); + return 1; + /* Yes, the directory could have been removed, but probably not. */ + } + + /* TODO: Create PID file. */ + + /* TODO: Save MDS_DISPLAY environment variable. */ + + /* Drop privileges. They most not be propagated non-authorised components. */ + /* setgid should not be set, but just to be safe we are restoring both user and group. */ + if ((seteuid(getuid()) < 0) || (setegid(getgid()) < 0)) + { + perror(*argv); + return 1; + } + + return 0; +} + + +/** + * Create directory for socket files, PID files and such + * + * @return Non-zero on error + */ +int create_runtime_root_directory(void) +{ + struct stat attr; + if (stat(MDS_RUNTIME_ROOT_DIRECTORY, &attr) == 0) { /* Cannot create the directory, its pathname refers to an existing. */ @@ -69,19 +127,23 @@ int main(int argc, const char** argv) } } else - /* Directory is missing, create it. */ - if (mkdir(MDS_RUNTIME_ROOT_DIRECTORY, 0755) < 0) - if (errno != EEXIST) /* Unlikely race condition. */ + { + /* Directory is missing, create it. */ + if (mkdir(MDS_RUNTIME_ROOT_DIRECTORY, S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH) < 0) { - perror(*argv); - return 1; + if (errno != EEXIST) /* Unlikely race condition. */ + { + perror(*argv); + return 1; + } } - - /* Drop privileges. They most not be propagated non-authorised components. */ - if (seteuid(getuid()) < 0) - { - perror(*argv); - return 1; + else + /* Set ownership. */ + if (chown(MDS_RUNTIME_ROOT_DIRECTORY, ROOT_USER_UID, ROOT_GROUP_GID) < 0) + { + perror(*argv); + return 1; + } } return 0; diff --git a/src/mds.h b/src/mds.h new file mode 100644 index 0000000..c03537d --- /dev/null +++ b/src/mds.h @@ -0,0 +1,31 @@ +/** + * mds — A micro-display server + * Copyright © 2014 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#ifndef MDS_MDS_H +#define MDS_MDS_H + + +/** + * Create directory for socket files, PID files and such + * + * @return Non-zero on error + */ +int create_runtime_root_directory(void); + + +#endif + |