From 6f7ee71165b30272a4f18bca361c324c7671680c Mon Sep 17 00:00:00 2001 From: David Oberhollenzer Date: Fri, 3 May 2019 23:33:41 +0200 Subject: unsquashfs: add flags to filter what file types to unpack This allows the user to skip stuff like device special files (which non-root can't create anyway) or to not create symlinks/fifos etc... Signed-off-by: David Oberhollenzer --- unpack/read_fstree.c | 59 ++++++++++++++++++++++++++++++++++++++++++++----- unpack/restore_fstree.c | 38 ++++++++++++++++++++++++------- unpack/unsquashfs.c | 48 +++++++++++++++++++++++++++++++++++----- unpack/unsquashfs.h | 16 ++++++++++++-- 4 files changed, 140 insertions(+), 21 deletions(-) diff --git a/unpack/read_fstree.c b/unpack/read_fstree.c index a6903b0..f200243 100644 --- a/unpack/read_fstree.c +++ b/unpack/read_fstree.c @@ -2,15 +2,36 @@ #include "unsquashfs.h" +static int should_skip(int type, int flags) +{ + switch (type) { + case SQFS_INODE_BDEV: + case SQFS_INODE_CDEV: + case SQFS_INODE_EXT_CDEV: + case SQFS_INODE_EXT_BDEV: + return (flags & UNPACK_NO_DEVICES); + case SQFS_INODE_SLINK: + case SQFS_INODE_EXT_SLINK: + return (flags & UNPACK_NO_SLINKS); + case SQFS_INODE_SOCKET: + case SQFS_INODE_EXT_SOCKET: + return(flags & UNPACK_NO_SOCKETS); + case SQFS_INODE_FIFO: + case SQFS_INODE_EXT_FIFO: + return (flags & UNPACK_NO_FIFO); + } + return 0; +} + static int fill_dir(meta_reader_t *ir, meta_reader_t *dr, tree_node_t *root, - sqfs_super_t *super, id_table_t *idtbl) + sqfs_super_t *super, id_table_t *idtbl, int flags) { sqfs_inode_generic_t *inode; sqfs_dir_header_t hdr; sqfs_dir_entry_t *ent; + tree_node_t *n, *prev; uint64_t block_start; size_t size, diff; - tree_node_t *n; uint32_t i; block_start = root->data.dir->start_block; @@ -35,6 +56,11 @@ static int fill_dir(meta_reader_t *ir, meta_reader_t *dr, tree_node_t *root, diff = sizeof(*ent) + strlen((char *)ent->name); size -= diff > size ? size : diff; + if (should_skip(ent->type, flags)) { + free(ent); + continue; + } + inode = meta_reader_read_inode(ir, super, hdr.start_block, ent->offset); @@ -58,17 +84,38 @@ static int fill_dir(meta_reader_t *ir, meta_reader_t *dr, tree_node_t *root, } } - for (n = root->data.dir->children; n != NULL; n = n->next) { + n = root->data.dir->children; + prev = NULL; + + while (n != NULL) { if (S_ISDIR(n->mode)) { - if (fill_dir(ir, dr, n, super, idtbl)) + if (fill_dir(ir, dr, n, super, idtbl, flags)) return -1; + + if (n->data.dir->children == NULL && + (flags & UNPACK_NO_EMPTY)) { + if (prev == NULL) { + root->data.dir->children = n->next; + free(n); + n = root->data.dir->children; + } else { + prev->next = n->next; + free(n); + n = prev->next; + } + continue; + } } + + prev = n; + n = n->next; } return 0; } -int read_fstree(fstree_t *out, int fd, sqfs_super_t *super, compressor_t *cmp) +int read_fstree(fstree_t *out, int fd, sqfs_super_t *super, compressor_t *cmp, + int flags) { sqfs_inode_generic_t *root; meta_reader_t *ir, *dr; @@ -119,7 +166,7 @@ int read_fstree(fstree_t *out, int fd, sqfs_super_t *super, compressor_t *cmp) if (out->root == NULL) goto out_id; - if (fill_dir(ir, dr, out->root, super, &idtbl)) + if (fill_dir(ir, dr, out->root, super, &idtbl, flags)) goto fail_fs; fstree_sort(out); diff --git a/unpack/restore_fstree.c b/unpack/restore_fstree.c index 56c3cc5..8ef21c3 100644 --- a/unpack/restore_fstree.c +++ b/unpack/restore_fstree.c @@ -3,14 +3,14 @@ static int restore_directory(int dirfd, tree_node_t *n, compressor_t *cmp, size_t block_size, frag_reader_t *frag, - int sqfsfd) + int sqfsfd, int flags) { int fd; for (n = n->data.dir->children; n != NULL; n = n->next) { switch (n->mode & S_IFMT) { case S_IFDIR: - if (mkdirat(dirfd, n->name, n->mode) && + if (mkdirat(dirfd, n->name, 0755) && errno != EEXIST) { fprintf(stderr, "mkdir %s: %s\n", n->name, strerror(errno)); @@ -25,7 +25,7 @@ static int restore_directory(int dirfd, tree_node_t *n, compressor_t *cmp, } if (restore_directory(fd, n, cmp, block_size, - frag, sqfsfd)) { + frag, sqfsfd, flags)) { close(fd); return -1; } @@ -42,7 +42,8 @@ static int restore_directory(int dirfd, tree_node_t *n, compressor_t *cmp, break; case S_IFSOCK: case S_IFIFO: - if (mknodat(dirfd, n->name, n->mode, 0)) { + if (mknodat(dirfd, n->name, + (n->mode & S_IFMT) | 0700, 0)) { fprintf(stderr, "creating %s: %s\n", n->name, strerror(errno)); return -1; @@ -50,7 +51,8 @@ static int restore_directory(int dirfd, tree_node_t *n, compressor_t *cmp, break; case S_IFBLK: case S_IFCHR: - if (mknodat(dirfd, n->name, n->mode, n->data.devno)) { + if (mknodat(dirfd, n->name, (n->mode & S_IFMT), + n->data.devno)) { fprintf(stderr, "creating device %s: %s\n", n->name, strerror(errno)); return -1; @@ -58,7 +60,7 @@ static int restore_directory(int dirfd, tree_node_t *n, compressor_t *cmp, break; case S_IFREG: fd = openat(dirfd, n->name, - O_WRONLY | O_CREAT | O_EXCL, n->mode); + O_WRONLY | O_CREAT | O_EXCL, 0600); if (fd < 0) { fprintf(stderr, "creating %s: %s\n", n->name, strerror(errno)); @@ -76,13 +78,32 @@ static int restore_directory(int dirfd, tree_node_t *n, compressor_t *cmp, default: break; } + + if (flags & UNPACK_CHOWN) { + if (fchownat(dirfd, n->name, n->uid, n->gid, + AT_SYMLINK_NOFOLLOW)) { + fprintf(stderr, "chown %s: %s\n", + n->name, strerror(errno)); + return -1; + } + } + + if (flags & UNPACK_CHMOD) { + if (fchmodat(dirfd, n->name, n->mode, + AT_SYMLINK_NOFOLLOW)) { + fprintf(stderr, "chmod %s: %s\n", + n->name, strerror(errno)); + return -1; + } + } } return 0; } int restore_fstree(const char *rootdir, tree_node_t *root, compressor_t *cmp, - size_t block_size, frag_reader_t *frag, int sqfsfd) + size_t block_size, frag_reader_t *frag, int sqfsfd, + int flags) { int dirfd; @@ -95,7 +116,8 @@ int restore_fstree(const char *rootdir, tree_node_t *root, compressor_t *cmp, return -1; } - if (restore_directory(dirfd, root, cmp, block_size, frag, sqfsfd)) { + if (restore_directory(dirfd, root, cmp, block_size, frag, + sqfsfd, flags)) { close(dirfd); return -1; } diff --git a/unpack/unsquashfs.c b/unpack/unsquashfs.c index 178def4..8ec1b94 100644 --- a/unpack/unsquashfs.c +++ b/unpack/unsquashfs.c @@ -12,11 +12,18 @@ static struct option long_opts[] = { { "list", required_argument, NULL, 'l' }, { "cat", required_argument, NULL, 'c' }, { "unpack-root", required_argument, NULL, 'u' }, + { "no-dev", no_argument, NULL, 'D' }, + { "no-sock", no_argument, NULL, 'S' }, + { "no-fifo", no_argument, NULL, 'F' }, + { "no-slink", no_argument, NULL, 'L' }, + { "no-empty-dir", no_argument, NULL, 'E' }, + { "chmod", no_argument, NULL, 'C' }, + { "chown", no_argument, NULL, 'O' }, { "help", no_argument, NULL, 'h' }, { "version", no_argument, NULL, 'V' }, }; -static const char *short_opts = "l:c:u:hV"; +static const char *short_opts = "l:c:u:DSFLCOEhV"; static const char *help_string = "Usage: %s [OPTIONS] \n" @@ -29,7 +36,17 @@ static const char *help_string = " --cat, -c If the specified path is a regular file in the,\n" " image, dump its contents to stdout.\n" " --unpack-root Unpack the contents of the filesystem into the\n" -" specified path\n" +" specified path.\n" +" --no-dev, -D Do not unpack device special files.\n" +" --no-sock, -S Do not unpack socket files.\n" +" --no-fifo, -F Do not unpack named pipes.\n" +" --no-slink, -L Do not unpack symbolic links.\n" +" --no-empty-dir, -E Do not unpack directories that would end up empty.\n" +" --chmod, -C Change permission flags of unpacked files to those\n" +" store in the squashfs image.\n" +" --chown, -O Change ownership of unpacked files to the UID/GID\n" +" set in the squashfs iamge.\n" +"\n" " --help, -h Print help text and exit.\n" " --version, -V Print version information and exit.\n" "\n"; @@ -92,7 +109,7 @@ static char *get_path(char *old, const char *arg) int main(int argc, char **argv) { - int i, fd, status = EXIT_FAILURE, op = OP_NONE; + int i, fd, status = EXIT_FAILURE, op = OP_NONE, unpack_flags = 0; const char *unpack_root = NULL; frag_reader_t *frag = NULL; char *cmdpath = NULL; @@ -107,6 +124,27 @@ int main(int argc, char **argv) break; switch (i) { + case 'D': + unpack_flags |= UNPACK_NO_DEVICES; + break; + case 'S': + unpack_flags |= UNPACK_NO_SOCKETS; + break; + case 'F': + unpack_flags |= UNPACK_NO_FIFO; + break; + case 'L': + unpack_flags |= UNPACK_NO_SLINKS; + break; + case 'C': + unpack_flags |= UNPACK_CHMOD; + break; + case 'O': + unpack_flags |= UNPACK_CHOWN; + break; + case 'E': + unpack_flags |= UNPACK_NO_EMPTY; + break; case 'c': op = OP_CAT; cmdpath = get_path(cmdpath, optarg); @@ -178,7 +216,7 @@ int main(int argc, char **argv) if (cmp == NULL) goto out_fd; - if (read_fstree(&fs, fd, &super, cmp)) + if (read_fstree(&fs, fd, &super, cmp, unpack_flags)) goto out_cmp; switch (op) { @@ -226,7 +264,7 @@ int main(int argc, char **argv) } if (restore_fstree(unpack_root, fs.root, cmp, super.block_size, - frag, fd)) { + frag, fd, unpack_flags)) { goto out_fs; } break; diff --git a/unpack/unsquashfs.h b/unpack/unsquashfs.h index 5895fb8..a8784fc 100644 --- a/unpack/unsquashfs.h +++ b/unpack/unsquashfs.h @@ -19,12 +19,23 @@ #include #include +enum UNPACK_FLAGS { + UNPACK_NO_DEVICES = 0x01, + UNPACK_NO_SOCKETS = 0x02, + UNPACK_NO_FIFO = 0x04, + UNPACK_NO_SLINKS = 0x08, + UNPACK_NO_EMPTY = 0x10, + UNPACK_CHMOD = 0x20, + UNPACK_CHOWN = 0x40, +}; + tree_node_t *tree_node_from_inode(sqfs_inode_generic_t *inode, const id_table_t *idtbl, const char *name, size_t block_size); -int read_fstree(fstree_t *out, int fd, sqfs_super_t *super, compressor_t *cmp); +int read_fstree(fstree_t *out, int fd, sqfs_super_t *super, compressor_t *cmp, + int flags); void list_files(tree_node_t *node); @@ -32,6 +43,7 @@ int extract_file(file_info_t *fi, compressor_t *cmp, size_t block_size, frag_reader_t *frag, int sqfsfd, int outfd); int restore_fstree(const char *rootdir, tree_node_t *root, compressor_t *cmp, - size_t block_size, frag_reader_t *frag, int sqfsfd); + size_t block_size, frag_reader_t *frag, int sqfsfd, + int flags); #endif /* UNSQUASHFS_H */ -- cgit v1.2.3