* [PATCH v2 0/2] ovl: allow O_PATH file descriptor when specifying layers
@ 2025-02-10 12:38 Christian Brauner
2025-02-10 12:38 ` [PATCH v2 1/2] fs: support O_PATH fds with FSCONFIG_SET_FD Christian Brauner
2025-02-10 12:39 ` [PATCH v2 2/2] selftests/overlayfs: test specifying layers as O_PATH file descriptors Christian Brauner
0 siblings, 2 replies; 5+ messages in thread
From: Christian Brauner @ 2025-02-10 12:38 UTC (permalink / raw)
To: linux-unionfs
Cc: Miklos Szeredi, Amir Goldstein, Mike Baynton, linux-fsdevel,
Christian Brauner
Allow overlayfs to use O_PATH file descriptors when specifying layers.
Userspace must currently use non-O_PATH file desriptors which is often
pointless especially if the file descriptors have been created via
open_tree(OPEN_TREE_CLONE). This has been a frequent request and came up
again in [1].
Link: https://lore.kernel.org/r/fd8f6574-f737-4743-b220-79c815ee1554@mbaynton.com [1]
Signed-off-by: Christian Brauner <brauner@kernel.org>
---
Changes in v2:
- Unconditionally enable O_PATH file descriptors.
- Link to v1: https://lore.kernel.org/r/20250207-work-overlayfs-v1-0-611976e73373@kernel.org
---
Christian Brauner (2):
fs: support O_PATH fds with FSCONFIG_SET_FD
selftests/overlayfs: test specifying layers as O_PATH file descriptors
fs/autofs/autofs_i.h | 2 +
fs/fsopen.c | 2 +-
.../filesystems/overlayfs/set_layers_via_fds.c | 65 ++++++++++++++++++++++
3 files changed, 68 insertions(+), 1 deletion(-)
---
base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b
change-id: 20250207-work-overlayfs-38fb9156d4c4
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH v2 1/2] fs: support O_PATH fds with FSCONFIG_SET_FD 2025-02-10 12:38 [PATCH v2 0/2] ovl: allow O_PATH file descriptor when specifying layers Christian Brauner @ 2025-02-10 12:38 ` Christian Brauner 2025-02-10 13:26 ` Amir Goldstein 2025-02-10 12:39 ` [PATCH v2 2/2] selftests/overlayfs: test specifying layers as O_PATH file descriptors Christian Brauner 1 sibling, 1 reply; 5+ messages in thread From: Christian Brauner @ 2025-02-10 12:38 UTC (permalink / raw) To: linux-unionfs Cc: Miklos Szeredi, Amir Goldstein, Mike Baynton, linux-fsdevel, Christian Brauner Let FSCONFIG_SET_FD handle O_PATH file descriptors. This is particularly useful in the context of overlayfs where layers can be specified via file descriptors instead of paths. But userspace must currently use non-O_PATH file desriptors which is often pointless especially if the file descriptors have been created via open_tree(OPEN_TREE_CLONE). Fixes: a08557d19ef41 ("ovl: specify layers via file descriptors") Signed-off-by: Christian Brauner <brauner@kernel.org> --- fs/autofs/autofs_i.h | 2 ++ fs/fsopen.c | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/autofs/autofs_i.h b/fs/autofs/autofs_i.h index 77c7991d89aa..23cea74f9933 100644 --- a/fs/autofs/autofs_i.h +++ b/fs/autofs/autofs_i.h @@ -218,6 +218,8 @@ void autofs_clean_ino(struct autofs_info *); static inline int autofs_check_pipe(struct file *pipe) { + if (pipe->f_mode & FMODE_PATH) + return -EINVAL; if (!(pipe->f_mode & FMODE_CAN_WRITE)) return -EINVAL; if (!S_ISFIFO(file_inode(pipe)->i_mode)) diff --git a/fs/fsopen.c b/fs/fsopen.c index 094a7f510edf..1aaf4cb2afb2 100644 --- a/fs/fsopen.c +++ b/fs/fsopen.c @@ -453,7 +453,7 @@ SYSCALL_DEFINE5(fsconfig, case FSCONFIG_SET_FD: param.type = fs_value_is_file; ret = -EBADF; - param.file = fget(aux); + param.file = fget_raw(aux); if (!param.file) goto out_key; param.dirfd = aux; -- 2.47.2 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2 1/2] fs: support O_PATH fds with FSCONFIG_SET_FD 2025-02-10 12:38 ` [PATCH v2 1/2] fs: support O_PATH fds with FSCONFIG_SET_FD Christian Brauner @ 2025-02-10 13:26 ` Amir Goldstein 2025-02-10 13:55 ` Christian Brauner 0 siblings, 1 reply; 5+ messages in thread From: Amir Goldstein @ 2025-02-10 13:26 UTC (permalink / raw) To: Christian Brauner Cc: linux-unionfs, Miklos Szeredi, Mike Baynton, linux-fsdevel On Mon, Feb 10, 2025 at 1:39 PM Christian Brauner <brauner@kernel.org> wrote: > > Let FSCONFIG_SET_FD handle O_PATH file descriptors. This is particularly > useful in the context of overlayfs where layers can be specified via > file descriptors instead of paths. But userspace must currently use > non-O_PATH file desriptors which is often pointless especially if > the file descriptors have been created via open_tree(OPEN_TREE_CLONE). > > Fixes: a08557d19ef41 ("ovl: specify layers via file descriptors") > Signed-off-by: Christian Brauner <brauner@kernel.org> > --- > fs/autofs/autofs_i.h | 2 ++ > fs/fsopen.c | 2 +- > 2 files changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/autofs/autofs_i.h b/fs/autofs/autofs_i.h > index 77c7991d89aa..23cea74f9933 100644 > --- a/fs/autofs/autofs_i.h > +++ b/fs/autofs/autofs_i.h > @@ -218,6 +218,8 @@ void autofs_clean_ino(struct autofs_info *); > > static inline int autofs_check_pipe(struct file *pipe) > { > + if (pipe->f_mode & FMODE_PATH) > + return -EINVAL; > if (!(pipe->f_mode & FMODE_CAN_WRITE)) > return -EINVAL; I thought you said the above check is redundant due to the lower check. In any case feel free to add Reviewed-by: Amir Goldstein <amir73il@gmail.com> > if (!S_ISFIFO(file_inode(pipe)->i_mode)) > diff --git a/fs/fsopen.c b/fs/fsopen.c > index 094a7f510edf..1aaf4cb2afb2 100644 > --- a/fs/fsopen.c > +++ b/fs/fsopen.c > @@ -453,7 +453,7 @@ SYSCALL_DEFINE5(fsconfig, > case FSCONFIG_SET_FD: > param.type = fs_value_is_file; > ret = -EBADF; > - param.file = fget(aux); > + param.file = fget_raw(aux); > if (!param.file) > goto out_key; > param.dirfd = aux; > > -- > 2.47.2 > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2 1/2] fs: support O_PATH fds with FSCONFIG_SET_FD 2025-02-10 13:26 ` Amir Goldstein @ 2025-02-10 13:55 ` Christian Brauner 0 siblings, 0 replies; 5+ messages in thread From: Christian Brauner @ 2025-02-10 13:55 UTC (permalink / raw) To: Amir Goldstein; +Cc: linux-unionfs, Miklos Szeredi, Mike Baynton, linux-fsdevel On Mon, Feb 10, 2025 at 02:26:56PM +0100, Amir Goldstein wrote: > On Mon, Feb 10, 2025 at 1:39 PM Christian Brauner <brauner@kernel.org> wrote: > > > > Let FSCONFIG_SET_FD handle O_PATH file descriptors. This is particularly > > useful in the context of overlayfs where layers can be specified via > > file descriptors instead of paths. But userspace must currently use > > non-O_PATH file desriptors which is often pointless especially if > > the file descriptors have been created via open_tree(OPEN_TREE_CLONE). > > > > Fixes: a08557d19ef41 ("ovl: specify layers via file descriptors") > > Signed-off-by: Christian Brauner <brauner@kernel.org> > > --- > > fs/autofs/autofs_i.h | 2 ++ > > fs/fsopen.c | 2 +- > > 2 files changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/fs/autofs/autofs_i.h b/fs/autofs/autofs_i.h > > index 77c7991d89aa..23cea74f9933 100644 > > --- a/fs/autofs/autofs_i.h > > +++ b/fs/autofs/autofs_i.h > > @@ -218,6 +218,8 @@ void autofs_clean_ino(struct autofs_info *); > > > > static inline int autofs_check_pipe(struct file *pipe) > > { > > + if (pipe->f_mode & FMODE_PATH) > > + return -EINVAL; > > if (!(pipe->f_mode & FMODE_CAN_WRITE)) > > return -EINVAL; > > I thought you said the above check is redundant due to the lower check. It is but that's only obvious to people quite familiar with VFS code. So I like the explicitly check here. > > In any case feel free to add > > Reviewed-by: Amir Goldstein <amir73il@gmail.com> > > > if (!S_ISFIFO(file_inode(pipe)->i_mode)) > > diff --git a/fs/fsopen.c b/fs/fsopen.c > > index 094a7f510edf..1aaf4cb2afb2 100644 > > --- a/fs/fsopen.c > > +++ b/fs/fsopen.c > > @@ -453,7 +453,7 @@ SYSCALL_DEFINE5(fsconfig, > > case FSCONFIG_SET_FD: > > param.type = fs_value_is_file; > > ret = -EBADF; > > - param.file = fget(aux); > > + param.file = fget_raw(aux); > > if (!param.file) > > goto out_key; > > param.dirfd = aux; > > > > -- > > 2.47.2 > > ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2 2/2] selftests/overlayfs: test specifying layers as O_PATH file descriptors 2025-02-10 12:38 [PATCH v2 0/2] ovl: allow O_PATH file descriptor when specifying layers Christian Brauner 2025-02-10 12:38 ` [PATCH v2 1/2] fs: support O_PATH fds with FSCONFIG_SET_FD Christian Brauner @ 2025-02-10 12:39 ` Christian Brauner 1 sibling, 0 replies; 5+ messages in thread From: Christian Brauner @ 2025-02-10 12:39 UTC (permalink / raw) To: linux-unionfs Cc: Miklos Szeredi, Amir Goldstein, Mike Baynton, linux-fsdevel, Christian Brauner Verify that userspace can specify layers via O_PATH file descriptors. Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Christian Brauner <brauner@kernel.org> --- .../filesystems/overlayfs/set_layers_via_fds.c | 65 ++++++++++++++++++++++ 1 file changed, 65 insertions(+) diff --git a/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c b/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c index 1d0ae785a667..e693e4102d22 100644 --- a/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c +++ b/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c @@ -214,4 +214,69 @@ TEST_F(set_layers_via_fds, set_500_layers_via_fds) ASSERT_EQ(close(fd_overlay), 0); } +TEST_F(set_layers_via_fds, set_500_layers_via_opath_fds) +{ + int fd_context, fd_tmpfs, fd_overlay, fd_work, fd_upper, fd_lower; + int layer_fds[500] = { [0 ... 499] = -EBADF }; + + ASSERT_EQ(unshare(CLONE_NEWNS), 0); + ASSERT_EQ(sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL), 0); + + fd_context = sys_fsopen("tmpfs", 0); + ASSERT_GE(fd_context, 0); + + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0); + fd_tmpfs = sys_fsmount(fd_context, 0, 0); + ASSERT_GE(fd_tmpfs, 0); + ASSERT_EQ(close(fd_context), 0); + + for (int i = 0; i < ARRAY_SIZE(layer_fds); i++) { + char path[100]; + + sprintf(path, "l%d", i); + ASSERT_EQ(mkdirat(fd_tmpfs, path, 0755), 0); + layer_fds[i] = openat(fd_tmpfs, path, O_DIRECTORY | O_PATH); + ASSERT_GE(layer_fds[i], 0); + } + + ASSERT_EQ(mkdirat(fd_tmpfs, "w", 0755), 0); + fd_work = openat(fd_tmpfs, "w", O_DIRECTORY | O_PATH); + ASSERT_GE(fd_work, 0); + + ASSERT_EQ(mkdirat(fd_tmpfs, "u", 0755), 0); + fd_upper = openat(fd_tmpfs, "u", O_DIRECTORY | O_PATH); + ASSERT_GE(fd_upper, 0); + + ASSERT_EQ(mkdirat(fd_tmpfs, "l501", 0755), 0); + fd_lower = openat(fd_tmpfs, "l501", O_DIRECTORY | O_PATH); + ASSERT_GE(fd_lower, 0); + + ASSERT_EQ(sys_move_mount(fd_tmpfs, "", -EBADF, "/tmp", MOVE_MOUNT_F_EMPTY_PATH), 0); + ASSERT_EQ(close(fd_tmpfs), 0); + + fd_context = sys_fsopen("overlay", 0); + ASSERT_GE(fd_context, 0); + + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "workdir", NULL, fd_work), 0); + ASSERT_EQ(close(fd_work), 0); + + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "upperdir", NULL, fd_upper), 0); + ASSERT_EQ(close(fd_upper), 0); + + for (int i = 0; i < ARRAY_SIZE(layer_fds); i++) { + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[i]), 0); + ASSERT_EQ(close(layer_fds[i]), 0); + } + + ASSERT_NE(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, fd_lower), 0); + ASSERT_EQ(close(fd_lower), 0); + + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0); + + fd_overlay = sys_fsmount(fd_context, 0, 0); + ASSERT_GE(fd_overlay, 0); + ASSERT_EQ(close(fd_context), 0); + ASSERT_EQ(close(fd_overlay), 0); +} + TEST_HARNESS_MAIN -- 2.47.2 ^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2025-02-10 13:55 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2025-02-10 12:38 [PATCH v2 0/2] ovl: allow O_PATH file descriptor when specifying layers Christian Brauner 2025-02-10 12:38 ` [PATCH v2 1/2] fs: support O_PATH fds with FSCONFIG_SET_FD Christian Brauner 2025-02-10 13:26 ` Amir Goldstein 2025-02-10 13:55 ` Christian Brauner 2025-02-10 12:39 ` [PATCH v2 2/2] selftests/overlayfs: test specifying layers as O_PATH file descriptors Christian Brauner
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