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Fix bug with -x --xattr read-only files

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Problem reported by Kevin Raymond in:
https://bugzilla.redhat.com/show_bug.cgi?id=1886540
* src/extract.c (open_output_file): If we already created the
empty file, do not open with O_EXCL, or with O_CREAT or O_TRUNC
for that matter.  Instead, use only O_NOFOLLOW to avoid some
races.  When estimating current mode, use openflag & O_EXCL rather
than overwriting_old_files.
(extract_file): Also invert S_IWUSR if it’s not set.
* tests/xattr08.at: New test.
* tests/Makefile.am, tests/testsuite.at: Add it.
This commit is contained in:
Paul Eggert
2022-08-26 16:39:16 -05:00
parent 258d1c44e5
commit 0b74885e81
4 changed files with 58 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/extract.c
+15 -16
View File
@@ -1189,14 +1189,12 @@ open_output_file (char const *file_name, int typeflag, mode_t mode,
int fd;
bool overwriting_old_files = old_files_option == OVERWRITE_OLD_FILES;
int openflag = (O_WRONLY | O_BINARY | O_CLOEXEC | O_NOCTTY | O_NONBLOCK
| O_CREAT
| (overwriting_old_files
? O_TRUNC | (dereference_option ? 0 : O_NOFOLLOW)
: O_EXCL));
/* File might be created in set_xattr. So clear O_EXCL to avoid open() fail */
if (file_created)
openflag = openflag & ~O_EXCL;
| (file_created
? O_NOFOLLOW
: (O_CREAT
| (overwriting_old_files
? O_TRUNC | (dereference_option ? 0 : O_NOFOLLOW)
: O_EXCL))));
if (typeflag == CONTTYPE)
{
@@ -1227,7 +1225,12 @@ open_output_file (char const *file_name, int typeflag, mode_t mode,
fd = openat (chdir_fd, file_name, openflag, mode);
if (0 <= fd)
{
if (overwriting_old_files)
if (openflag & O_EXCL)
{
*current_mode = mode & ~ current_umask;
*current_mode_mask = MODE_RWX;
}
else
{
struct stat st;
if (fstat (fd, &st) != 0)
@@ -1246,11 +1249,6 @@ open_output_file (char const *file_name, int typeflag, mode_t mode,
*current_mode = st.st_mode;
*current_mode_mask = ALL_MODE_BITS;
}
else
{
*current_mode = mode & ~ current_umask;
*current_mode_mask = MODE_RWX;
}
}
return fd;
@@ -1268,8 +1266,9 @@ extract_file (char *file_name, int typeflag)
bool interdir_made = false;
mode_t mode = (current_stat_info.stat.st_mode & MODE_RWX
& ~ (0 < same_owner_option ? S_IRWXG | S_IRWXO : 0));
mode_t invert_permissions = 0 < same_owner_option ? mode & (S_IRWXG | S_IRWXO)
: 0;
mode_t invert_permissions
= ((0 < same_owner_option ? mode & (S_IRWXG | S_IRWXO) : 0)
| ((mode & S_IWUSR) ^ S_IWUSR));
mode_t current_mode = 0;
mode_t current_mode_mask = 0;