diff options
| author | Jori Koolstra <jkoolstra@xs4all.nl> | 2026-04-24 14:46:02 +0300 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2026-05-21 11:53:33 +0300 |
| commit | 31cf44efa6df72a524b40adefb80539f3a4e13ba (patch) | |
| tree | 7ff56857adc3f9756dce98b28a7179256aeac61d /include | |
| parent | 3e0be8ccff090cde4e10410f8e6a3fefeeff4124 (diff) | |
| download | linux-31cf44efa6df72a524b40adefb80539f3a4e13ba.tar.xz | |
vfs: add O_EMPTYPATH to openat(2)/openat2(2)
To get an operable version of an O_PATH file descriptor, it is possible
to use openat(fd, ".", O_DIRECTORY) for directories, but other files
currently require going through open("/proc/<pid>/fd/<nr>"), which
depends on a functioning procfs.
This patch adds the O_EMPTYPATH flag to openat(2)/openat2(2). If passed,
LOOKUP_EMPTY is set at path resolution time.
Note: This implies that you cannot rely anymore on disabling procfs from
being mounted (e.g. inside a container without procfs mounted and with
CAP_SYS_ADMIN dropped) to prevent O_PATH fds from being re-opened
read-write.
Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
Link: https://patch.msgid.link/20260424114611.1678641-2-jkoolstra@xs4all.nl
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/fcntl.h | 2 | ||||
| -rw-r--r-- | include/uapi/asm-generic/fcntl.h | 4 |
2 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h index a332e79b3207..c65c5c73d362 100644 --- a/include/linux/fcntl.h +++ b/include/linux/fcntl.h @@ -10,7 +10,7 @@ (O_RDONLY | O_WRONLY | O_RDWR | O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC | \ O_APPEND | O_NDELAY | O_NONBLOCK | __O_SYNC | O_DSYNC | \ FASYNC | O_DIRECT | O_LARGEFILE | O_DIRECTORY | O_NOFOLLOW | \ - O_NOATIME | O_CLOEXEC | O_PATH | __O_TMPFILE) + O_NOATIME | O_CLOEXEC | O_PATH | __O_TMPFILE | O_EMPTYPATH) /* List of all valid flags for the how->resolve argument: */ #define VALID_RESOLVE_FLAGS \ diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h index 613475285643..bfc68156b45a 100644 --- a/include/uapi/asm-generic/fcntl.h +++ b/include/uapi/asm-generic/fcntl.h @@ -88,6 +88,10 @@ #define __O_TMPFILE 020000000 #endif +#ifndef O_EMPTYPATH +#define O_EMPTYPATH (1 << 26) /* allow empty path */ +#endif + /* a horrid kludge trying to make sure that this will fail on old kernels */ #define O_TMPFILE (__O_TMPFILE | O_DIRECTORY) |