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busybox-static.20467
tar-unzip-postpone-creation-of-symlinks-with-su...
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File tar-unzip-postpone-creation-of-symlinks-with-suspicious-targets.patch of Package busybox-static.20467
From: Denys Vlasenko <vda.linux@googlemail.com> Date: Tue Feb 20 15:57:45 2018 +0100 Subject: tar,unzip: postpone creation of symlinks with "suspicious" targets Patch-mainline: a84db18fc71d09e801df0ebca048d82e90b32c6a Git-repo: https://git.busybox.net/busybox Git-commit: 02ea1240675e5e94661b4c0b63ee0b0f2f84a71f References: This mostly reverts commit bc9bbeb2b81001e8731cd2ae501c8fccc8d87cc7 "libarchive: do not extract unsafe symlinks unless $EXTRACT_UNSAFE_SYMLINKS=1" Users report that it is somewhat too restrictive. See https://bugs.busybox.net/show_bug.cgi?id=8411 In particular, this interferes with unpacking of busybox-based filesystems with links like "sbin/applet" -> "../bin/busybox". The change is made smaller by deleting ARCHIVE_EXTRACT_QUIET flag - it is unused since 2010, and removing conditionals on it allows commonalizing some error message codes. function old new delta create_or_remember_symlink - 94 +94 create_symlinks_from_list - 64 +64 tar_main 1002 1006 +4 unzip_main 2732 2724 -8 data_extract_all 984 891 -93 unsafe_symlink_target 147 - -147 ------------------------------------------------------------------------------ (add/remove: 2/1 grow/shrink: 1/2 up/down: 162/-248) Total: -86 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com> Signed-off-by: Egbert Eich <eich@suse.de> --- archival/libarchive/data_extract_all.c | 28 ++++---------- archival/libarchive/unsafe_symlink_target.c | 59 +++++++++++++---------------- archival/tar.c | 2 + archival/unzip.c | 25 ++++++------ include/bb_archive.h | 23 ++++++----- testsuite/tar.tests | 10 ++--- 6 files changed, 68 insertions(+), 79 deletions(-) diff --git a/archival/libarchive/data_extract_all.c b/archival/libarchive/data_extract_all.c index e658444e0..5ada3caa2 100644 --- a/archival/libarchive/data_extract_all.c +++ b/archival/libarchive/data_extract_all.c @@ -108,9 +108,7 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle) } } else if (existing_sb.st_mtime >= file_header->mtime) { - if (!(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET) - && !S_ISDIR(file_header->mode) - ) { + if (!S_ISDIR(file_header->mode)) { bb_error_msg("%s not created: newer or " "same age file exists", dst_name); } @@ -126,7 +124,7 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle) /* Handle hard links separately */ if (hard_link) { res = link(hard_link, dst_name); - if (res != 0 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)) { + if (res != 0) { /* shared message */ bb_perror_msg("can't create %slink '%s' to '%s'", "hard", dst_name, hard_link @@ -166,10 +164,9 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle) } case S_IFDIR: res = mkdir(dst_name, file_header->mode); - if ((res == -1) + if ((res != 0) && (errno != EISDIR) /* btw, Linux doesn't return this */ && (errno != EEXIST) - && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET) ) { bb_perror_msg("can't make dir %s", dst_name); } @@ -199,27 +196,16 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle) * * Untarring bug.tar would otherwise place evil.py in '/tmp'. */ - if (!unsafe_symlink_target(file_header->link_target)) { - res = symlink(file_header->link_target, dst_name); - if (res != 0 - && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET) - ) { - /* shared message */ - bb_perror_msg("can't create %slink '%s' to '%s'", - "sym", - dst_name, file_header->link_target - ); - } - } + create_or_remember_symlink(&archive_handle->symlink_placeholders, + file_header->link_target, + dst_name); break; case S_IFSOCK: case S_IFBLK: case S_IFCHR: case S_IFIFO: res = mknod(dst_name, file_header->mode, file_header->device); - if ((res == -1) - && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET) - ) { + if (res != 0) { bb_perror_msg("can't create node %s", dst_name); } break; diff --git a/archival/libarchive/unsafe_symlink_target.c b/archival/libarchive/unsafe_symlink_target.c index 441ba8b24..8dcafeaa1 100644 --- a/archival/libarchive/unsafe_symlink_target.c +++ b/archival/libarchive/unsafe_symlink_target.c @@ -5,44 +5,37 @@ #include "libbb.h" #include "bb_archive.h" -int FAST_FUNC unsafe_symlink_target(const char *target) +void FAST_FUNC create_or_remember_symlink(llist_t **symlink_placeholders, + const char *target, + const char *linkname) { - const char *dot; - - if (target[0] == '/') { - const char *var; - unsafe: - var = getenv("EXTRACT_UNSAFE_SYMLINKS"); - if (var) { - if (LONE_CHAR(var, '1')) - return 0; /* pretend it's safe */ - return 1; /* "UNSAFE!" */ - } - bb_error_msg("skipping unsafe symlink to '%s' in archive," - " set %s=1 to extract", - target, - "EXTRACT_UNSAFE_SYMLINKS" + if (target[0] == '/' || strstr(target, "..")) { + llist_add_to(symlink_placeholders, + xasprintf("%s%c%s", linkname, '\0', target) + ); + return; + } + if (symlink(target, linkname) != 0) { + /* shared message */ + bb_perror_msg_and_die("can't create %slink '%s' to '%s'", + "sym", linkname, target ); - /* Prevent further messages */ - setenv("EXTRACT_UNSAFE_SYMLINKS", "0", 0); - return 1; /* "UNSAFE!" */ } +} - dot = target; - for (;;) { - dot = strchr(dot, '.'); - if (!dot) - return 0; /* safe target */ +void FAST_FUNC create_symlinks_from_list(llist_t *list) +{ + while (list) { + char *target; - /* Is it a path component starting with ".."? */ - if ((dot[1] == '.') - && (dot == target || dot[-1] == '/') - /* Is it exactly ".."? */ - && (dot[2] == '/' || dot[2] == '\0') - ) { - goto unsafe; + target = list->data + strlen(list->data) + 1; + if (symlink(target, list->data)) { + /* shared message */ + bb_error_msg_and_die("can't create %slink '%s' to '%s'", + "sym", + list->data, target + ); } - /* NB: it can even be trailing ".", should only add 1 */ - dot += 1; + list = list->link; } } diff --git a/archival/tar.c b/archival/tar.c index 8e3002ab4..4a03379d0 100644 --- a/archival/tar.c +++ b/archival/tar.c @@ -1240,6 +1240,8 @@ int tar_main(int argc UNUSED_PARAM, char **argv) while (get_header_tar(tar_handle) == EXIT_SUCCESS) bb_got_signal = EXIT_SUCCESS; /* saw at least one header, good */ + create_symlinks_from_list(tar_handle->symlink_placeholders); + /* Check that every file that should have been extracted was */ while (tar_handle->accept) { if (!find_list_entry(tar_handle->reject, tar_handle->accept->data) diff --git a/archival/unzip.c b/archival/unzip.c index 683c96c03..fb15f5f15 100644 --- a/archival/unzip.c +++ b/archival/unzip.c @@ -331,7 +331,9 @@ static void unzip_create_leading_dirs(const char *fn) } #if ENABLE_FEATURE_UNZIP_CDF -static void unzip_extract_symlink(zip_header_t *zip, const char *dst_fn) +static void unzip_extract_symlink(llist_t **symlink_placeholders, + zip_header_t *zip, + const char *dst_fn) { char *target; @@ -357,15 +359,9 @@ static void unzip_extract_symlink(zip_header_t *zip, const char *dst_fn) target[xstate.mem_output_size] = '\0'; #endif } - if (!unsafe_symlink_target(target)) { -//TODO: libbb candidate - if (symlink(target, dst_fn)) { - /* shared message */ - bb_perror_msg_and_die("can't create %slink '%s' to '%s'", - "sym", dst_fn, target - ); - } - } + create_or_remember_symlink(symlink_placeholders, + target, + dst_fn); free(target); } #endif @@ -469,6 +465,9 @@ int unzip_main(int argc, char **argv) llist_t *zaccept = NULL; llist_t *zreject = NULL; char *base_dir = NULL; +#if ENABLE_FEATURE_UNZIP_CDF + llist_t *symlink_placeholders = NULL; +#endif int i; char key_buf[80]; /* must match size used by my_fgets80 */ @@ -917,7 +916,7 @@ int unzip_main(int argc, char **argv) #if ENABLE_FEATURE_UNZIP_CDF if (S_ISLNK(file_mode)) { if (dst_fd != STDOUT_FILENO) /* not -p? */ - unzip_extract_symlink(&zip, dst_fn); + unzip_extract_symlink(&symlink_placeholders, &zip, dst_fn); } else #endif { @@ -953,6 +952,10 @@ int unzip_main(int argc, char **argv) total_entries++; } +#if ENABLE_FEATURE_UNZIP_CDF + create_symlinks_from_list(symlink_placeholders); +#endif + if ((opts & OPT_l) && quiet <= 1) { if (!verbose) { // " Length Date Time Name\n" diff --git a/include/bb_archive.h b/include/bb_archive.h index d3a02cf18..05dba700a 100644 --- a/include/bb_archive.h +++ b/include/bb_archive.h @@ -64,6 +64,9 @@ typedef struct archive_handle_t { /* Currently processed file's header */ file_header_t *file_header; + /* List of symlink placeholders */ + llist_t *symlink_placeholders; + /* Process the header component, e.g. tar -t */ void FAST_FUNC (*action_header)(const file_header_t *); @@ -119,15 +122,14 @@ typedef struct archive_handle_t { #define ARCHIVE_RESTORE_DATE (1 << 0) #define ARCHIVE_CREATE_LEADING_DIRS (1 << 1) #define ARCHIVE_UNLINK_OLD (1 << 2) -#define ARCHIVE_EXTRACT_QUIET (1 << 3) -#define ARCHIVE_EXTRACT_NEWER (1 << 4) -#define ARCHIVE_DONT_RESTORE_OWNER (1 << 5) -#define ARCHIVE_DONT_RESTORE_PERM (1 << 6) -#define ARCHIVE_NUMERIC_OWNER (1 << 7) -#define ARCHIVE_O_TRUNC (1 << 8) -#define ARCHIVE_REMEMBER_NAMES (1 << 9) +#define ARCHIVE_EXTRACT_NEWER (1 << 3) +#define ARCHIVE_DONT_RESTORE_OWNER (1 << 4) +#define ARCHIVE_DONT_RESTORE_PERM (1 << 5) +#define ARCHIVE_NUMERIC_OWNER (1 << 6) +#define ARCHIVE_O_TRUNC (1 << 7) +#define ARCHIVE_REMEMBER_NAMES (1 << 8) #if ENABLE_RPM -#define ARCHIVE_REPLACE_VIA_RENAME (1 << 10) +#define ARCHIVE_REPLACE_VIA_RENAME (1 << 9) #endif @@ -197,7 +199,10 @@ void seek_by_jump(int fd, off_t amount) FAST_FUNC; void seek_by_read(int fd, off_t amount) FAST_FUNC; const char *strip_unsafe_prefix(const char *str) FAST_FUNC; -int unsafe_symlink_target(const char *target) FAST_FUNC; +void create_or_remember_symlink(llist_t **symlink_placeholders, + const char *target, + const char *linkname) FAST_FUNC; +void create_symlinks_from_list(llist_t *list) FAST_FUNC; void data_align(archive_handle_t *archive_handle, unsigned boundary) FAST_FUNC; const llist_t *find_list_entry(const llist_t *list, const char *filename) FAST_FUNC; diff --git a/testsuite/tar.tests b/testsuite/tar.tests index b7cd74ca5..1675b07b1 100755 --- a/testsuite/tar.tests +++ b/testsuite/tar.tests @@ -279,7 +279,7 @@ optional UUDECODE FEATURE_TAR_AUTODETECT FEATURE_SEAMLESS_BZ2 testing "tar does not extract into symlinks" "\ >>/tmp/passwd && uudecode -o input && tar xf input 2>&1 && rm passwd; cat /tmp/passwd; echo \$? " "\ -tar: skipping unsafe symlink to '/tmp/passwd' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract +tar: can't create symlink 'passwd' to '/tmp/passwd' 0 " \ "" "\ @@ -299,7 +299,7 @@ optional UUDECODE FEATURE_TAR_AUTODETECT FEATURE_SEAMLESS_BZ2 testing "tar -k does not extract into symlinks" "\ >>/tmp/passwd && uudecode -o input && tar xf input -k 2>&1 && rm passwd; cat /tmp/passwd; echo \$? " "\ -tar: skipping unsafe symlink to '/tmp/passwd' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract +tar: can't create symlink 'passwd' to '/tmp/passwd' 0 " \ "" "\ @@ -324,11 +324,11 @@ rm -rf etc usr ' "\ etc/ssl/certs/3b2716e5.0 etc/ssl/certs/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem -tar: skipping unsafe symlink to '/usr/share/ca-certificates/mozilla/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.crt' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract etc/ssl/certs/f80cc7f6.0 usr/share/ca-certificates/mozilla/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.crt 0 etc/ssl/certs/3b2716e5.0 -> EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem +etc/ssl/certs/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem -> /usr/share/ca-certificates/mozilla/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.crt etc/ssl/certs/f80cc7f6.0 -> EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem " \ "" "" @@ -346,9 +346,9 @@ ls symlink/bb_test_evilfile ' "\ anything.txt symlink -tar: skipping unsafe symlink to '/tmp' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract symlink/bb_test_evilfile -0 +tar: can't create symlink 'symlink' to '/tmp' +1 ls: /tmp/bb_test_evilfile: No such file or directory ls: bb_test_evilfile: No such file or directory symlink/bb_test_evilfile
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