appimage type 2 support

3 files changed, 173 insertions, 3 deletions

diff --git a/src/firejail/appimage.c b/src/firejail/appimage.c
index 375d6be24..3f03c28bf 100644
--- a/src/firejail/appimage.c
+++ b/src/firejail/appimage.c
@@ -39,7 +39,7 @@ void appimage_set(const char *appimage_path) {
         assert(appimage_path);
         assert(devloop == NULL);        // don't call this twice!
         EUID_ASSERT();
-
+        
 #ifdef LOOP_CTL_GET_FREE        // test for older kernels; this definition is found in /usr/include/linux/loop.h
         // check appimage_path
         if (access(appimage_path, R_OK) == -1) {
@@ -47,6 +47,12 @@ void appimage_set(const char *appimage_path) {
                 exit(1);
         }
 
+        // get appimage type and ELF size
+        // a value of 0 means we are dealing with a type1 appimage
+        long unsigned int size = appimage2_size(appimage_path);
+        if (arg_debug)
+                printf("AppImage ELF size %lu\n", size);
+
         // open as user to prevent race condition
         int ffd = open(appimage_path, O_RDONLY|O_CLOEXEC);
         if (ffd == -1) {
@@ -76,6 +82,15 @@ void appimage_set(const char *appimage_path) {
                 fprintf(stderr, "Error: cannot configure the loopback device\n");
                 exit(1);
         }
+        
+        if (size) {
+                struct loop_info64 info;
+                memset(&info, 0, sizeof(struct loop_info64));
+                info.lo_offset = size;
+                if (ioctl(lfd,  LOOP_SET_STATUS64, &info) == -1)
+                        errExit("configure appimage offset");
+        }
+        
         close(lfd);
         close(ffd);
         EUID_USER();
@@ -100,8 +115,16 @@ void appimage_set(const char *appimage_path) {
         if (asprintf(&mode, "mode=700,uid=%d,gid=%d", getuid(), getgid()) == -1)
                 errExit("asprintf");
         EUID_ROOT();
-        if (mount(devloop, mntdir, "iso9660",MS_MGC_VAL|MS_RDONLY,  mode) < 0)
-                errExit("mounting appimage");
+        
+        if (size == 0) {
+                if (mount(devloop, mntdir, "iso9660",MS_MGC_VAL|MS_RDONLY,  mode) < 0)
+                        errExit("mounting appimage");
+        }
+        else {
+                if (mount(devloop, mntdir, "squashfs",MS_MGC_VAL|MS_RDONLY,  mode) < 0)
+                        errExit("mounting appimage");
+        }
+
         if (arg_debug)
                 printf("appimage mounted on %s\n", mntdir);
         EUID_USER();
diff --git a/src/firejail/appimage_size.c b/src/firejail/appimage_size.c
new file mode 100644
index 000000000..c8b3d28c5
--- /dev/null
+++ b/src/firejail/appimage_size.c
@@ -0,0 +1,143 @@
+/*
+Compile with:
+gcc elfsize.c -o elfsize
+Example:
+ls -l                                           126584
+Calculation using the values also reported by readelf -h:
+Start of section headers        e_shoff         124728
+Size of section headers         e_shentsize     64
+Number of section headers       e_shnum         29
+e_shoff + ( e_shentsize * e_shnum ) =           126584
+*/
+
+#include <elf.h>
+#include <byteswap.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <fcntl.h>
+
+typedef Elf32_Nhdr Elf_Nhdr;
+
+static Elf64_Ehdr ehdr;
+static Elf64_Phdr *phdr;
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define ELFDATANATIVE ELFDATA2LSB
+#elif __BYTE_ORDER == __BIG_ENDIAN
+#define ELFDATANATIVE ELFDATA2MSB
+#else
+#error "Unknown machine endian"
+#endif
+
+static uint16_t file16_to_cpu(uint16_t val) {
+        if (ehdr.e_ident[EI_DATA] != ELFDATANATIVE)
+                val = bswap_16(val);
+        return val;
+}
+
+
+static uint32_t file32_to_cpu(uint32_t val) {
+        if (ehdr.e_ident[EI_DATA] != ELFDATANATIVE)
+                val = bswap_32(val);
+        return val;
+}
+
+
+static uint64_t file64_to_cpu(uint64_t val) {
+        if (ehdr.e_ident[EI_DATA] != ELFDATANATIVE)
+                val = bswap_64(val);
+        return val;
+}
+
+
+// return 0 if error
+static long unsigned int read_elf32(int fd) {
+        Elf32_Ehdr ehdr32;
+        ssize_t ret, i;
+
+        ret = pread(fd, &ehdr32, sizeof(ehdr32), 0);
+        if (ret < 0 || (size_t)ret != sizeof(ehdr))
+                return 0;
+
+        ehdr.e_shoff            = file32_to_cpu(ehdr32.e_shoff);
+        ehdr.e_shentsize        = file16_to_cpu(ehdr32.e_shentsize);
+        ehdr.e_shnum            = file16_to_cpu(ehdr32.e_shnum);
+
+        return(ehdr.e_shoff + (ehdr.e_shentsize * ehdr.e_shnum));
+}
+
+
+// return 0 if error
+static long unsigned int read_elf64(int fd) {
+        Elf64_Ehdr ehdr64;
+        ssize_t ret, i;
+
+        ret = pread(fd, &ehdr64, sizeof(ehdr64), 0);
+        if (ret < 0 || (size_t)ret != sizeof(ehdr))
+                return 0;
+
+        ehdr.e_shoff            = file64_to_cpu(ehdr64.e_shoff);
+        ehdr.e_shentsize        = file16_to_cpu(ehdr64.e_shentsize);
+        ehdr.e_shnum            = file16_to_cpu(ehdr64.e_shnum);
+
+        return(ehdr.e_shoff + (ehdr.e_shentsize * ehdr.e_shnum));
+}
+
+
+// return 0 if error
+// return 0 if this is not an appimgage2 file
+long unsigned int appimage2_size(const char *fname) {
+/* TODO, FIXME: This assumes that the section header table (SHT) is
+the last part of the ELF. This is usually the case but
+it could also be that the last section is the last part
+of the ELF. This should be checked for.
+*/
+        ssize_t ret;
+        int fd;
+        long unsigned int size = 0;
+
+        fd = open(fname, O_RDONLY);
+        if (fd < 0)
+                return 0;
+
+        ret = pread(fd, ehdr.e_ident, EI_NIDENT, 0);
+        if (ret != EI_NIDENT)
+                goto getout;
+
+        if ((ehdr.e_ident[EI_DATA] != ELFDATA2LSB) &&
+             (ehdr.e_ident[EI_DATA] != ELFDATA2MSB))
+                goto getout;
+
+        if(ehdr.e_ident[EI_CLASS] == ELFCLASS32) {
+                size = read_elf32(fd);
+        }
+        else if(ehdr.e_ident[EI_CLASS] == ELFCLASS64) {
+                size = read_elf64(fd);
+        }
+        else {
+                goto getout;
+        }
+        if (size == 0)
+                goto getout;
+
+
+        // look for a LZMA header at this location
+        unsigned char buf[4];
+        ret = pread(fd, buf, 4, size);
+        if (ret != 4) {
+                size = 0;
+                goto getout;
+        }
+        if (memcmp(buf, "hsqs", 4) != 0)
+                size = 0;
+
+getout:
+        close(fd);
+        return size;
+}
+
+
diff --git a/src/firejail/firejail.h b/src/firejail/firejail.h
index dafa5919c..9a9bb1ae7 100644
--- a/src/firejail/firejail.h
+++ b/src/firejail/firejail.h
@@ -681,8 +681,12 @@ void appimage_set(const char *appimage_path);
 void appimage_clear(void);
 const char *appimage_getdir(void);
 
+// appimage_size.c
+long unsigned int appimage2_size(const char *fname);
+
 // cmdline.c
 void build_cmdline(char **command_line, char **window_title, int argc, char **argv, int index);
 
+
 #endif