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b97902b62a
Pull openat2 fixes from Christian Brauner:
- Remove the unused VALID_UPGRADE_FLAGS define we carried from an
extension to openat2() that we haven't merged. Aleksa might be
getting back to it at some point but just not right now.
- openat2() used to accidently ignore unknown flag values in the upper
32 bits.
The new openat2() syscall verifies that no unknown O-flag values are
set and returns an error to userspace if they are while the older
open syscalls like open() and openat() simply ignore unknown flag
values:
#define O_FLAG_CURRENTLY_INVALID (1 << 31)
struct open_how how = {
.flags = O_RDONLY | O_FLAG_CURRENTLY_INVALID,
.resolve = 0,
};
/* fails */
fd = openat2(-EBADF, "/dev/null", &how, sizeof(how));
/* succeeds */
fd = openat(-EBADF, "/dev/null", O_RDONLY | O_FLAG_CURRENTLY_INVALID);
However, openat2() silently truncates the upper 32 bits meaning:
#define O_FLAG_CURRENTLY_INVALID_LOWER32 (1 << 31)
#define O_FLAG_CURRENTLY_INVALID_UPPER32 (1 << 40)
struct open_how how_lowe32 = {
.flags = O_RDONLY | O_FLAG_CURRENTLY_INVALID_LOWER32,
};
struct open_how how_upper32 = {
.flags = O_RDONLY | O_FLAG_CURRENTLY_INVALID_UPPER32,
};
/* fails */
fd = openat2(-EBADF, "/dev/null", &how_lower32, sizeof(how_lower32));
/* succeeds */
fd = openat2(-EBADF, "/dev/null", &how_upper32, sizeof(how_upper32));
Fix this by preventing the immediate truncation in build_open_flags()
and add a compile-time check to catch when we add flags in the upper
32 bit range.
* tag 'fs.openat2.unknown_flags.v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
test: add openat2() test for invalid upper 32 bit flag value
open: don't silently ignore unknown O-flags in openat2()
fcntl: remove unused VALID_UPGRADE_FLAGS
Linux kernel
============
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