ujail: rework fs jail part

Change functions to work with full paths (do less split and concat of path)
  Store "soname" as key and the fullpath as path in "libraries"
  Remove "extras" list and replace it with "mounts" avl_tree
  ("mounts" also store fullpath)

Add add_path_and_deps() function to handle file/lib openning and mmaping
  Check if file is an elf (magic number) before passing it to elf_load_deps()
  elf_load_deps() now only handle elf parsing part
  next commit adds script (#!) handling

Use add_path_and_deps() with -r and -w args to automatically add dependencies

Signed-off-by: Etienne CHAMPETIER <champetier.etienne@gmail.com>

1 files changed, 24 insertions, 74 deletions

diff --git a/jail/elf.c b/jail/elf.c
index 46c19df..136789e 100644
--- a/jail/elf.c
+++ b/jail/elf.c
@@ -12,14 +12,10 @@
  */
 
 #define _GNU_SOURCE
-#include <sys/mman.h>
 
-#include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <fcntl.h>
-#include <libgen.h>
 #include <glob.h>
 #include <elf.h>
 #include <linux/limits.h>
@@ -27,6 +23,7 @@
 #include <libubox/utils.h>
 
 #include "elf.h"
+#include "fs.h"
 #include "log.h"
 
 struct avl_tree libraries;
@@ -52,7 +49,11 @@ static void alloc_library_path(const char *path)
 	DEBUG("adding ld.so path %s\n", path);
 }
 
-static void alloc_library(const char *path, const char *name)
+/*
+ * path = full path
+ * name = soname/avl key
+ */
+void alloc_library(const char *path, const char *name)
 {
 	struct library *l;
 	char *_name, *_path;
@@ -67,47 +68,38 @@ static void alloc_library(const char *path, const char *name)
 	l->path = strcpy(_path, path);
 
 	avl_insert(&libraries, &l->avl);
-	DEBUG("adding library %s/%s\n", path, name);
+	DEBUG("adding library %s (%s)\n", path, name);
 }
 
-static int elf_open(char **dir, const char *file)
+int lib_open(char **fullpath, const char *file)
 {
 	struct library_path *p;
 	char path[PATH_MAX];
 	int fd = -1;
 
-	*dir = NULL;
+	*fullpath = NULL;
 
 	list_for_each_entry(p, &library_paths, list) {
-		if (strlen(p->path))
-			snprintf(path, sizeof(path), "%s/%s", p->path, file);
-		else
-			strncpy(path, file, sizeof(path));
+		snprintf(path, sizeof(path), "%s/%s", p->path, file);
 		fd = open(path, O_RDONLY);
 		if (fd >= 0) {
-			*dir = p->path;
+			*fullpath = strdup(path);
 			break;
 		}
 	}
 
-	if (fd == -1)
-		fd = open(file, O_RDONLY);
-
 	return fd;
 }
 
 const char* find_lib(const char *file)
 {
 	struct library *l;
-	static char path[PATH_MAX];
 
 	l = avl_find_element(&libraries, file, l, avl);
 	if (!l)
 		return NULL;
 
-	snprintf(path, sizeof(path), "%s/%s", l->path, file);
-
-	return path;
+	return l->path;
 }
 
 static int elf64_find_section(const char *map, unsigned int type, unsigned int *offset, unsigned int *size, unsigned int *vaddr)
@@ -197,7 +189,7 @@ static int elf32_scan_dynamic(const char *map, int dyn_offset, int dyn_size, int
 		if (curr->d_tag != DT_NEEDED)
 			continue;
 
-		if (elf_load_deps(&strtab[curr->d_un.d_val]))
+		if (add_path_and_deps(&strtab[curr->d_un.d_val], 1, -1, 1))
 			return -1;
 	}
 
@@ -231,79 +223,37 @@ static int elf64_scan_dynamic(const char *map, int dyn_offset, int dyn_size, int
 		if (curr->d_tag != DT_NEEDED)
 			continue;
 
-		if (elf_load_deps(&strtab[curr->d_un.d_val]))
+		if (add_path_and_deps(&strtab[curr->d_un.d_val], 1, -1, 1))
 			return -1;
 	}
 
 	return 0;
 }
 
-int elf_load_deps(const char *library)
+int elf_load_deps(const char *path, const char *map)
 {
 	unsigned int dyn_offset, dyn_size;
 	unsigned int load_offset, load_vaddr;
-	struct stat s;
-	char *map = NULL, *dir = NULL;
-	int clazz, fd, ret = -1;
-
-	if (avl_find(&libraries, library))
-		return 0;
-
-	fd = elf_open(&dir, library);
-
-	if (fd < 0) {
-		ERROR("failed to open %s\n", library);
-		return -1;
-	}
-
-	if (fstat(fd, &s) == -1) {
-		ERROR("failed to stat %s\n", library);
-		ret = -1;
-		goto err_out;
-	}
-
-	map = mmap(NULL, s.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
-	if (map == MAP_FAILED) {
-		ERROR("failed to mmap %s\n", library);
-		ret = -1;
-		goto err_out;
-	}
 
 	if (elf_find_section(map, PT_LOAD, &load_offset, NULL, &load_vaddr)) {
-		ERROR("failed to load the .load section from %s\n", library);
-		ret = -1;
-		goto err_out;
+		ERROR("failed to load the .load section from %s\n", path);
+		return -1;
 	}
 
 	if (elf_find_section(map, PT_DYNAMIC, &dyn_offset, &dyn_size, NULL)) {
-		ERROR("failed to load the .dynamic section from %s\n", library);
-		ret = -1;
-		goto err_out;
+		ERROR("failed to load the .dynamic section from %s\n", path);
+		return -1;
 	}
 
-	if (dir) {
-		alloc_library(dir, library);
-	} else {
-		char *elf1 = strdup(library);
-		char *elf2 = strdup(library);
-
-		alloc_library(dirname(elf1), basename(elf2));
-		free(elf1);
-		free(elf2);
-	}
-	clazz = map[EI_CLASS];
+	int clazz = map[EI_CLASS];
 
 	if (clazz == ELFCLASS32)
-		ret = elf32_scan_dynamic(map, dyn_offset, dyn_size, load_vaddr - load_offset);
+		return elf32_scan_dynamic(map, dyn_offset, dyn_size, load_vaddr - load_offset);
 	else if (clazz == ELFCLASS64)
-		ret = elf64_scan_dynamic(map, dyn_offset, dyn_size, load_vaddr - load_offset);
-
-err_out:
-	if (map)
-		munmap(map, s.st_size);
-	close(fd);
+		return elf64_scan_dynamic(map, dyn_offset, dyn_size, load_vaddr - load_offset);
 
-	return ret;
+	ERROR("unknown elf format %d\n", clazz);
+	return -1;
 }
 
 static void load_ldso_conf(const char *conf)