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fd-util: refuse O_CREAT in fd_reopen

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O_CREAT doesn't make sense for fd_reopen, since we're
working on an already opened fd. Also, in fd_reopen
we don't handle the mode parameter of open(2), which
means we may get runtime error like #29938.
This commit is contained in:
Mike Yuan
2023-11-09 03:35:56 +08:00
parent e5883df89f
commit 05314c9c87
1 changed files with 6 additions and 11 deletions
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src/basic/fd-util.c
+6 -11
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@@ -761,9 +761,10 @@ finish:
}
int fd_reopen(int fd, int flags) {
int new_fd, r;
int r;
assert(fd >= 0 || fd == AT_FDCWD);
assert(!FLAGS_SET(flags, O_CREAT));
/* Reopens the specified fd with new flags. This is useful for convert an O_PATH fd into a regular one, or to
* turn O_RDWR fds into O_RDONLY fds.
@@ -787,19 +788,12 @@ int fd_reopen(int fd, int flags) {
* the same way as the non-O_DIRECTORY case. */
return -ELOOP;
if (FLAGS_SET(flags, O_DIRECTORY) || fd == AT_FDCWD) {
if (FLAGS_SET(flags, O_DIRECTORY) || fd == AT_FDCWD)
/* If we shall reopen the fd as directory we can just go via "." and thus bypass the whole
* magic /proc/ directory, and make ourselves independent of that being mounted. */
new_fd = openat(fd, ".", flags | O_DIRECTORY);
if (new_fd < 0)
return -errno;
return RET_NERRNO(openat(fd, ".", flags | O_DIRECTORY));
return new_fd;
}
assert(fd >= 0);
new_fd = open(FORMAT_PROC_FD_PATH(fd), flags);
int new_fd = open(FORMAT_PROC_FD_PATH(fd), flags);
if (new_fd < 0) {
if (errno != ENOENT)
return -errno;
@@ -825,6 +819,7 @@ int fd_reopen_condition(
int r, new_fd;
assert(fd >= 0);
assert(!FLAGS_SET(flags, O_CREAT));
/* Invokes fd_reopen(fd, flags), but only if the existing F_GETFL flags don't match the specified
* flags (masked by the specified mask). This is useful for converting O_PATH fds into real fds if