| Message ID | 1649763226-2329-2-git-send-email-xuyang2018.jy@fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3,1/5] idmapped-mounts: Reset errno to zero after detect fs_allow_idmap | expand |
On Tue, Apr 12, 2022 at 07:33:43PM +0800, Yang Xu wrote: > Since mknodat can create file, we should also check whether strip S_ISGID. > Also add new helper caps_down_fsetid to drop CAP_FSETID because strip S_ISGID > depend on this cap and keep other cap(ie CAP_MKNOD) because create character > device needs it when using mknod. > > Only test mknodat with character device in setgid_create function and the another > two functions test mknodat with whiteout device. > > Since kernel commit a3c751a50 ("vfs: allow unprivileged whiteout creation") in > v5.8-rc1, we can create whiteout device in userns test. Since kernel 5.12, mount_setattr > and MOUNT_ATTR_IDMAP was supported, we don't need to detect kernel whether allow > unprivileged whiteout creation. Using fs_allow_idmap as a proxy is safe. > > Tested-by: Christian Brauner (Microsoft)<brauner@kernel.org> > Reviewed-by: Christian Brauner (Microsoft)<brauner@kernel.org> > Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com> > --- > src/idmapped-mounts/idmapped-mounts.c | 219 +++++++++++++++++++++++++- > 1 file changed, 213 insertions(+), 6 deletions(-) > > diff --git a/src/idmapped-mounts/idmapped-mounts.c b/src/idmapped-mounts/idmapped-mounts.c > index 8e6405c5..617f56e0 100644 > --- a/src/idmapped-mounts/idmapped-mounts.c > +++ b/src/idmapped-mounts/idmapped-mounts.c > @@ -241,6 +241,34 @@ static inline bool caps_supported(void) > return ret; > } > > +static int caps_down_fsetid(void) > +{ > + bool fret = false; > +#ifdef HAVE_SYS_CAPABILITY_H > + cap_t caps = NULL; > + cap_value_t cap = CAP_FSETID; > + int ret = -1; > + > + caps = cap_get_proc(); > + if (!caps) > + goto out; > + > + ret = cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap, 0); > + if (ret) > + goto out; > + > + ret = cap_set_proc(caps); > + if (ret) > + goto out; > + > + fret = true; > + > +out: > + cap_free(caps); > +#endif > + return fret; > +} > + > /* caps_down - lower all effective caps */ > static int caps_down(void) > { > @@ -7805,8 +7833,8 @@ out_unmap: > #endif /* HAVE_LIBURING_H */ > > /* The following tests are concerned with setgid inheritance. These can be > - * filesystem type specific. For xfs, if a new file or directory is created > - * within a setgid directory and irix_sgid_inhiert is set then inherit the > + * filesystem type specific. For xfs, if a new file or directory or node is > + * created within a setgid directory and irix_sgid_inhiert is set then inherit the > * setgid bit if the caller is in the group of the directory. > */ > static int setgid_create(void) > @@ -7863,18 +7891,44 @@ static int setgid_create(void) > if (!is_setgid(t_dir1_fd, DIR1, 0)) > die("failure: is_setgid"); > > + /* create a special file via mknodat() vfs_create */ > + if (mknodat(t_dir1_fd, FILE2, S_IFREG | S_ISGID | S_IXGRP, 0)) > + die("failure: mknodat"); > + > + if (!is_setgid(t_dir1_fd, FILE2, 0)) > + die("failure: is_setgid"); > + > + /* create a character device via mknodat() vfs_mknod */ > + if (mknodat(t_dir1_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, makedev(5, 1))) > + die("failure: mknodat"); > + > + if (!is_setgid(t_dir1_fd, CHRDEV1, 0)) > + die("failure: is_setgid"); > + > if (!expected_uid_gid(t_dir1_fd, FILE1, 0, 0, 0)) > die("failure: check ownership"); > > if (!expected_uid_gid(t_dir1_fd, DIR1, 0, 0, 0)) > die("failure: check ownership"); > > + if (!expected_uid_gid(t_dir1_fd, FILE2, 0, 0, 0)) > + die("failure: check ownership"); > + > + if (!expected_uid_gid(t_dir1_fd, CHRDEV1, 0, 0, 0)) > + die("failure: check ownership"); > + > if (unlinkat(t_dir1_fd, FILE1, 0)) > die("failure: delete"); > > if (unlinkat(t_dir1_fd, DIR1, AT_REMOVEDIR)) > die("failure: delete"); > > + if (unlinkat(t_dir1_fd, FILE2, 0)) > + die("failure: delete"); > + > + if (unlinkat(t_dir1_fd, CHRDEV1, 0)) > + die("failure: delete"); > + > exit(EXIT_SUCCESS); > } > if (wait_for_pid(pid)) > @@ -7889,8 +7943,8 @@ static int setgid_create(void) > if (!switch_ids(0, 10000)) > die("failure: switch_ids"); > > - if (!caps_down()) > - die("failure: caps_down"); > + if (!caps_down_fsetid()) > + die("failure: caps_down_fsetid"); > > /* create regular file via open() */ > file1_fd = openat(t_dir1_fd, FILE1, O_CREAT | O_EXCL | O_CLOEXEC, S_IXGRP | S_ISGID); > @@ -7917,6 +7971,19 @@ static int setgid_create(void) > die("failure: is_setgid"); > } Please see my comment on the earlier thread: https://lore.kernel.org/linux-fsdevel/20220407134009.s4shhomfxjz5cf5r@wittgenstein The same issue still exists afaict, i.e. you're not handling the irix case.
on 2022/4/13 15:59, Christian Brauner wrote: > On Tue, Apr 12, 2022 at 07:33:43PM +0800, Yang Xu wrote: >> Since mknodat can create file, we should also check whether strip S_ISGID. >> Also add new helper caps_down_fsetid to drop CAP_FSETID because strip S_ISGID >> depend on this cap and keep other cap(ie CAP_MKNOD) because create character >> device needs it when using mknod. >> >> Only test mknodat with character device in setgid_create function and the another >> two functions test mknodat with whiteout device. >> >> Since kernel commit a3c751a50 ("vfs: allow unprivileged whiteout creation") in >> v5.8-rc1, we can create whiteout device in userns test. Since kernel 5.12, mount_setattr >> and MOUNT_ATTR_IDMAP was supported, we don't need to detect kernel whether allow >> unprivileged whiteout creation. Using fs_allow_idmap as a proxy is safe. >> >> Tested-by: Christian Brauner (Microsoft)<brauner@kernel.org> >> Reviewed-by: Christian Brauner (Microsoft)<brauner@kernel.org> >> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com> >> --- >> src/idmapped-mounts/idmapped-mounts.c | 219 +++++++++++++++++++++++++- >> 1 file changed, 213 insertions(+), 6 deletions(-) >> >> diff --git a/src/idmapped-mounts/idmapped-mounts.c b/src/idmapped-mounts/idmapped-mounts.c >> index 8e6405c5..617f56e0 100644 >> --- a/src/idmapped-mounts/idmapped-mounts.c >> +++ b/src/idmapped-mounts/idmapped-mounts.c >> @@ -241,6 +241,34 @@ static inline bool caps_supported(void) >> return ret; >> } >> >> +static int caps_down_fsetid(void) >> +{ >> + bool fret = false; >> +#ifdef HAVE_SYS_CAPABILITY_H >> + cap_t caps = NULL; >> + cap_value_t cap = CAP_FSETID; >> + int ret = -1; >> + >> + caps = cap_get_proc(); >> + if (!caps) >> + goto out; >> + >> + ret = cap_set_flag(caps, CAP_EFFECTIVE, 1,&cap, 0); >> + if (ret) >> + goto out; >> + >> + ret = cap_set_proc(caps); >> + if (ret) >> + goto out; >> + >> + fret = true; >> + >> +out: >> + cap_free(caps); >> +#endif >> + return fret; >> +} >> + >> /* caps_down - lower all effective caps */ >> static int caps_down(void) >> { >> @@ -7805,8 +7833,8 @@ out_unmap: >> #endif /* HAVE_LIBURING_H */ >> >> /* The following tests are concerned with setgid inheritance. These can be >> - * filesystem type specific. For xfs, if a new file or directory is created >> - * within a setgid directory and irix_sgid_inhiert is set then inherit the >> + * filesystem type specific. For xfs, if a new file or directory or node is >> + * created within a setgid directory and irix_sgid_inhiert is set then inherit the >> * setgid bit if the caller is in the group of the directory. >> */ >> static int setgid_create(void) >> @@ -7863,18 +7891,44 @@ static int setgid_create(void) >> if (!is_setgid(t_dir1_fd, DIR1, 0)) >> die("failure: is_setgid"); >> >> + /* create a special file via mknodat() vfs_create */ >> + if (mknodat(t_dir1_fd, FILE2, S_IFREG | S_ISGID | S_IXGRP, 0)) >> + die("failure: mknodat"); >> + >> + if (!is_setgid(t_dir1_fd, FILE2, 0)) >> + die("failure: is_setgid"); >> + >> + /* create a character device via mknodat() vfs_mknod */ >> + if (mknodat(t_dir1_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, makedev(5, 1))) >> + die("failure: mknodat"); >> + >> + if (!is_setgid(t_dir1_fd, CHRDEV1, 0)) >> + die("failure: is_setgid"); >> + >> if (!expected_uid_gid(t_dir1_fd, FILE1, 0, 0, 0)) >> die("failure: check ownership"); >> >> if (!expected_uid_gid(t_dir1_fd, DIR1, 0, 0, 0)) >> die("failure: check ownership"); >> >> + if (!expected_uid_gid(t_dir1_fd, FILE2, 0, 0, 0)) >> + die("failure: check ownership"); >> + >> + if (!expected_uid_gid(t_dir1_fd, CHRDEV1, 0, 0, 0)) >> + die("failure: check ownership"); >> + >> if (unlinkat(t_dir1_fd, FILE1, 0)) >> die("failure: delete"); >> >> if (unlinkat(t_dir1_fd, DIR1, AT_REMOVEDIR)) >> die("failure: delete"); >> >> + if (unlinkat(t_dir1_fd, FILE2, 0)) >> + die("failure: delete"); >> + >> + if (unlinkat(t_dir1_fd, CHRDEV1, 0)) >> + die("failure: delete"); >> + >> exit(EXIT_SUCCESS); >> } >> if (wait_for_pid(pid)) >> @@ -7889,8 +7943,8 @@ static int setgid_create(void) >> if (!switch_ids(0, 10000)) >> die("failure: switch_ids"); >> >> - if (!caps_down()) >> - die("failure: caps_down"); >> + if (!caps_down_fsetid()) >> + die("failure: caps_down_fsetid"); >> >> /* create regular file via open() */ >> file1_fd = openat(t_dir1_fd, FILE1, O_CREAT | O_EXCL | O_CLOEXEC, S_IXGRP | S_ISGID); >> @@ -7917,6 +7971,19 @@ static int setgid_create(void) >> die("failure: is_setgid"); >> } > > Please see my comment on the earlier thread: > https://lore.kernel.org/linux-fsdevel/20220407134009.s4shhomfxjz5cf5r@wittgenstein > > The same issue still exists afaict, i.e. you're not handling the irix > case. I remember it has two issues 1)replace 0755 with valid flags 2)consider fs.xfs.irix_sgid_inherit enable situation because it will strip S_ISGID for directory I used t_dir1_fd directory instead of old DIR1, so I don't need to raise the S_ISGID when we enable fs.xfs.irix_sgid_inherit. I have tested this on enable and disable fs.xfs.irix_sgid_inherit situations, they all pass. Or I miss something? Best Regards Yang Xu
On Wed, Apr 13, 2022 at 08:31:45AM +0000, xuyang2018.jy@fujitsu.com wrote: > on 2022/4/13 15:59, Christian Brauner wrote: > > On Tue, Apr 12, 2022 at 07:33:43PM +0800, Yang Xu wrote: > >> Since mknodat can create file, we should also check whether strip S_ISGID. > >> Also add new helper caps_down_fsetid to drop CAP_FSETID because strip S_ISGID > >> depend on this cap and keep other cap(ie CAP_MKNOD) because create character > >> device needs it when using mknod. > >> > >> Only test mknodat with character device in setgid_create function and the another > >> two functions test mknodat with whiteout device. > >> > >> Since kernel commit a3c751a50 ("vfs: allow unprivileged whiteout creation") in > >> v5.8-rc1, we can create whiteout device in userns test. Since kernel 5.12, mount_setattr > >> and MOUNT_ATTR_IDMAP was supported, we don't need to detect kernel whether allow > >> unprivileged whiteout creation. Using fs_allow_idmap as a proxy is safe. > >> > >> Tested-by: Christian Brauner (Microsoft)<brauner@kernel.org> > >> Reviewed-by: Christian Brauner (Microsoft)<brauner@kernel.org> > >> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com> > >> --- > >> src/idmapped-mounts/idmapped-mounts.c | 219 +++++++++++++++++++++++++- > >> 1 file changed, 213 insertions(+), 6 deletions(-) > >> > >> diff --git a/src/idmapped-mounts/idmapped-mounts.c b/src/idmapped-mounts/idmapped-mounts.c > >> index 8e6405c5..617f56e0 100644 > >> --- a/src/idmapped-mounts/idmapped-mounts.c > >> +++ b/src/idmapped-mounts/idmapped-mounts.c > >> @@ -241,6 +241,34 @@ static inline bool caps_supported(void) > >> return ret; > >> } > >> > >> +static int caps_down_fsetid(void) > >> +{ > >> + bool fret = false; > >> +#ifdef HAVE_SYS_CAPABILITY_H > >> + cap_t caps = NULL; > >> + cap_value_t cap = CAP_FSETID; > >> + int ret = -1; > >> + > >> + caps = cap_get_proc(); > >> + if (!caps) > >> + goto out; > >> + > >> + ret = cap_set_flag(caps, CAP_EFFECTIVE, 1,&cap, 0); > >> + if (ret) > >> + goto out; > >> + > >> + ret = cap_set_proc(caps); > >> + if (ret) > >> + goto out; > >> + > >> + fret = true; > >> + > >> +out: > >> + cap_free(caps); > >> +#endif > >> + return fret; > >> +} > >> + > >> /* caps_down - lower all effective caps */ > >> static int caps_down(void) > >> { > >> @@ -7805,8 +7833,8 @@ out_unmap: > >> #endif /* HAVE_LIBURING_H */ > >> > >> /* The following tests are concerned with setgid inheritance. These can be > >> - * filesystem type specific. For xfs, if a new file or directory is created > >> - * within a setgid directory and irix_sgid_inhiert is set then inherit the > >> + * filesystem type specific. For xfs, if a new file or directory or node is > >> + * created within a setgid directory and irix_sgid_inhiert is set then inherit the > >> * setgid bit if the caller is in the group of the directory. > >> */ > >> static int setgid_create(void) > >> @@ -7863,18 +7891,44 @@ static int setgid_create(void) > >> if (!is_setgid(t_dir1_fd, DIR1, 0)) > >> die("failure: is_setgid"); > >> > >> + /* create a special file via mknodat() vfs_create */ > >> + if (mknodat(t_dir1_fd, FILE2, S_IFREG | S_ISGID | S_IXGRP, 0)) > >> + die("failure: mknodat"); > >> + > >> + if (!is_setgid(t_dir1_fd, FILE2, 0)) > >> + die("failure: is_setgid"); > >> + > >> + /* create a character device via mknodat() vfs_mknod */ > >> + if (mknodat(t_dir1_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, makedev(5, 1))) > >> + die("failure: mknodat"); > >> + > >> + if (!is_setgid(t_dir1_fd, CHRDEV1, 0)) > >> + die("failure: is_setgid"); > >> + > >> if (!expected_uid_gid(t_dir1_fd, FILE1, 0, 0, 0)) > >> die("failure: check ownership"); > >> > >> if (!expected_uid_gid(t_dir1_fd, DIR1, 0, 0, 0)) > >> die("failure: check ownership"); > >> > >> + if (!expected_uid_gid(t_dir1_fd, FILE2, 0, 0, 0)) > >> + die("failure: check ownership"); > >> + > >> + if (!expected_uid_gid(t_dir1_fd, CHRDEV1, 0, 0, 0)) > >> + die("failure: check ownership"); > >> + > >> if (unlinkat(t_dir1_fd, FILE1, 0)) > >> die("failure: delete"); > >> > >> if (unlinkat(t_dir1_fd, DIR1, AT_REMOVEDIR)) > >> die("failure: delete"); > >> > >> + if (unlinkat(t_dir1_fd, FILE2, 0)) > >> + die("failure: delete"); > >> + > >> + if (unlinkat(t_dir1_fd, CHRDEV1, 0)) > >> + die("failure: delete"); > >> + > >> exit(EXIT_SUCCESS); > >> } > >> if (wait_for_pid(pid)) > >> @@ -7889,8 +7943,8 @@ static int setgid_create(void) > >> if (!switch_ids(0, 10000)) > >> die("failure: switch_ids"); > >> > >> - if (!caps_down()) > >> - die("failure: caps_down"); > >> + if (!caps_down_fsetid()) > >> + die("failure: caps_down_fsetid"); > >> > >> /* create regular file via open() */ > >> file1_fd = openat(t_dir1_fd, FILE1, O_CREAT | O_EXCL | O_CLOEXEC, S_IXGRP | S_ISGID); > >> @@ -7917,6 +7971,19 @@ static int setgid_create(void) > >> die("failure: is_setgid"); > >> } > > > > Please see my comment on the earlier thread: > > https://lore.kernel.org/linux-fsdevel/20220407134009.s4shhomfxjz5cf5r@wittgenstein > > > > The same issue still exists afaict, i.e. you're not handling the irix > > case. > I remember it has two issues > 1)replace 0755 with valid flags > 2)consider fs.xfs.irix_sgid_inherit enable situation because it will > strip S_ISGID for directory > > I used t_dir1_fd directory instead of old DIR1, so I don't need to raise Ah, sorry, I missed this. Then this should all be fine: Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
diff --git a/src/idmapped-mounts/idmapped-mounts.c b/src/idmapped-mounts/idmapped-mounts.c index 8e6405c5..617f56e0 100644 --- a/src/idmapped-mounts/idmapped-mounts.c +++ b/src/idmapped-mounts/idmapped-mounts.c @@ -241,6 +241,34 @@ static inline bool caps_supported(void) return ret; } +static int caps_down_fsetid(void) +{ + bool fret = false; +#ifdef HAVE_SYS_CAPABILITY_H + cap_t caps = NULL; + cap_value_t cap = CAP_FSETID; + int ret = -1; + + caps = cap_get_proc(); + if (!caps) + goto out; + + ret = cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap, 0); + if (ret) + goto out; + + ret = cap_set_proc(caps); + if (ret) + goto out; + + fret = true; + +out: + cap_free(caps); +#endif + return fret; +} + /* caps_down - lower all effective caps */ static int caps_down(void) { @@ -7805,8 +7833,8 @@ out_unmap: #endif /* HAVE_LIBURING_H */ /* The following tests are concerned with setgid inheritance. These can be - * filesystem type specific. For xfs, if a new file or directory is created - * within a setgid directory and irix_sgid_inhiert is set then inherit the + * filesystem type specific. For xfs, if a new file or directory or node is + * created within a setgid directory and irix_sgid_inhiert is set then inherit the * setgid bit if the caller is in the group of the directory. */ static int setgid_create(void) @@ -7863,18 +7891,44 @@ static int setgid_create(void) if (!is_setgid(t_dir1_fd, DIR1, 0)) die("failure: is_setgid"); + /* create a special file via mknodat() vfs_create */ + if (mknodat(t_dir1_fd, FILE2, S_IFREG | S_ISGID | S_IXGRP, 0)) + die("failure: mknodat"); + + if (!is_setgid(t_dir1_fd, FILE2, 0)) + die("failure: is_setgid"); + + /* create a character device via mknodat() vfs_mknod */ + if (mknodat(t_dir1_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, makedev(5, 1))) + die("failure: mknodat"); + + if (!is_setgid(t_dir1_fd, CHRDEV1, 0)) + die("failure: is_setgid"); + if (!expected_uid_gid(t_dir1_fd, FILE1, 0, 0, 0)) die("failure: check ownership"); if (!expected_uid_gid(t_dir1_fd, DIR1, 0, 0, 0)) die("failure: check ownership"); + if (!expected_uid_gid(t_dir1_fd, FILE2, 0, 0, 0)) + die("failure: check ownership"); + + if (!expected_uid_gid(t_dir1_fd, CHRDEV1, 0, 0, 0)) + die("failure: check ownership"); + if (unlinkat(t_dir1_fd, FILE1, 0)) die("failure: delete"); if (unlinkat(t_dir1_fd, DIR1, AT_REMOVEDIR)) die("failure: delete"); + if (unlinkat(t_dir1_fd, FILE2, 0)) + die("failure: delete"); + + if (unlinkat(t_dir1_fd, CHRDEV1, 0)) + die("failure: delete"); + exit(EXIT_SUCCESS); } if (wait_for_pid(pid)) @@ -7889,8 +7943,8 @@ static int setgid_create(void) if (!switch_ids(0, 10000)) die("failure: switch_ids"); - if (!caps_down()) - die("failure: caps_down"); + if (!caps_down_fsetid()) + die("failure: caps_down_fsetid"); /* create regular file via open() */ file1_fd = openat(t_dir1_fd, FILE1, O_CREAT | O_EXCL | O_CLOEXEC, S_IXGRP | S_ISGID); @@ -7917,6 +7971,19 @@ static int setgid_create(void) die("failure: is_setgid"); } + /* create a special file via mknodat() vfs_create */ + if (mknodat(t_dir1_fd, FILE2, S_IFREG | S_ISGID | S_IXGRP, 0)) + die("failure: mknodat"); + + if (is_setgid(t_dir1_fd, FILE2, 0)) + die("failure: is_setgid"); + + /* create a character device via mknodat() vfs_mknod */ + if (mknodat(t_dir1_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, makedev(5, 1))) + die("failure: mknodat"); + + if (is_setgid(t_dir1_fd, CHRDEV1, 0)) + die("failure: is_setgid"); /* * In setgid directories newly created files always inherit the * gid from the parent directory. Verify that the file is owned @@ -7933,6 +8000,24 @@ static int setgid_create(void) if (!expected_uid_gid(t_dir1_fd, DIR1, 0, 0, 0)) die("failure: check ownership"); + if (!expected_uid_gid(t_dir1_fd, FILE2, 0, 0, 0)) + die("failure: check ownership"); + + if (!expected_uid_gid(t_dir1_fd, CHRDEV1, 0, 0, 0)) + die("failure: check ownership"); + + if (unlinkat(t_dir1_fd, FILE1, 0)) + die("failure: delete"); + + if (unlinkat(t_dir1_fd, DIR1, AT_REMOVEDIR)) + die("failure: delete"); + + if (unlinkat(t_dir1_fd, FILE2, 0)) + die("failure: delete"); + + if (unlinkat(t_dir1_fd, CHRDEV1, 0)) + die("failure: delete"); + exit(EXIT_SUCCESS); } if (wait_for_pid(pid)) @@ -8035,6 +8120,20 @@ static int setgid_create_idmapped(void) die("failure: is_setgid"); } + /* create a special file via mknodat() vfs_create */ + if (mknodat(open_tree_fd, FILE2, S_IFREG | S_ISGID | S_IXGRP, 0)) + die("failure: mknodat"); + + if (is_setgid(open_tree_fd, FILE2, 0)) + die("failure: is_setgid"); + + /* create a whiteout device via mknodat() vfs_mknod */ + if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0)) + die("failure: mknodat"); + + if (is_setgid(open_tree_fd, CHRDEV1, 0)) + die("failure: is_setgid"); + /* * In setgid directories newly created files always inherit the * gid from the parent directory. Verify that the file is owned @@ -8051,6 +8150,24 @@ static int setgid_create_idmapped(void) if (!expected_uid_gid(open_tree_fd, DIR1, 0, 10000, 10000)) die("failure: check ownership"); + if (!expected_uid_gid(open_tree_fd, FILE2, 0, 10000, 10000)) + die("failure: check ownership"); + + if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 10000, 10000)) + die("failure: check ownership"); + + if (unlinkat(open_tree_fd, FILE1, 0)) + die("failure: delete"); + + if (unlinkat(open_tree_fd, DIR1, AT_REMOVEDIR)) + die("failure: delete"); + + if (unlinkat(open_tree_fd, FILE2, 0)) + die("failure: delete"); + + if (unlinkat(open_tree_fd, CHRDEV1, 0)) + die("failure: delete"); + exit(EXIT_SUCCESS); } if (wait_for_pid(pid)) @@ -8149,18 +8266,44 @@ static int setgid_create_idmapped_in_userns(void) if (!is_setgid(open_tree_fd, DIR1, 0)) die("failure: is_setgid"); + /* create a special file via mknodat() vfs_create */ + if (mknodat(open_tree_fd, FILE2, S_IFREG | S_ISGID | S_IXGRP, 0)) + die("failure: mknodat"); + + if (!is_setgid(open_tree_fd, FILE2, 0)) + die("failure: is_setgid"); + + /* create a whiteout device via mknodat() vfs_mknod */ + if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0)) + die("failure: mknodat"); + + if (!is_setgid(open_tree_fd, CHRDEV1, 0)) + die("failure: is_setgid"); + if (!expected_uid_gid(open_tree_fd, FILE1, 0, 0, 0)) die("failure: check ownership"); if (!expected_uid_gid(open_tree_fd, DIR1, 0, 0, 0)) die("failure: check ownership"); + if (!expected_uid_gid(open_tree_fd, FILE2, 0, 0, 0)) + die("failure: check ownership"); + + if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 0)) + die("failure: check ownership"); + if (unlinkat(open_tree_fd, FILE1, 0)) die("failure: delete"); if (unlinkat(open_tree_fd, DIR1, AT_REMOVEDIR)) die("failure: delete"); + if (unlinkat(open_tree_fd, FILE2, 0)) + die("failure: delete"); + + if (unlinkat(open_tree_fd, CHRDEV1, 0)) + die("failure: delete"); + exit(EXIT_SUCCESS); } if (wait_for_pid(pid)) @@ -8190,9 +8333,12 @@ static int setgid_create_idmapped_in_userns(void) exit(EXIT_SUCCESS); } - if (!switch_userns(attr.userns_fd, 0, 0, true)) + if (!switch_userns(attr.userns_fd, 0, 0, false)) die("failure: switch_userns"); + if (!caps_down_fsetid()) + die("failure: caps_down_fsetid"); + /* create regular file via open() */ file1_fd = openat(open_tree_fd, FILE1, O_CREAT | O_EXCL | O_CLOEXEC, S_IXGRP | S_ISGID); if (file1_fd < 0) @@ -8218,6 +8364,20 @@ static int setgid_create_idmapped_in_userns(void) die("failure: is_setgid"); } + /* create a special file via mknodat() vfs_create */ + if (mknodat(open_tree_fd, FILE2, S_IFREG | S_ISGID | S_IXGRP, 0)) + die("failure: mknodat"); + + if (is_setgid(open_tree_fd, FILE2, 0)) + die("failure: is_setgid"); + + /* create a whiteout device via mknodat() vfs_mknod */ + if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0)) + die("failure: mknodat"); + + if (is_setgid(open_tree_fd, CHRDEV1, 0)) + die("failure: is_setgid"); + /* * In setgid directories newly created files always inherit the * gid from the parent directory. Verify that the file is owned @@ -8234,12 +8394,24 @@ static int setgid_create_idmapped_in_userns(void) if (!expected_uid_gid(open_tree_fd, DIR1, 0, 0, 1000)) die("failure: check ownership"); + if (!expected_uid_gid(open_tree_fd, FILE2, 0, 0, 1000)) + die("failure: check ownership"); + + if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 1000)) + die("failure: check ownership"); + if (unlinkat(open_tree_fd, FILE1, 0)) die("failure: delete"); if (unlinkat(open_tree_fd, DIR1, AT_REMOVEDIR)) die("failure: delete"); + if (unlinkat(open_tree_fd, FILE2, 0)) + die("failure: delete"); + + if (unlinkat(open_tree_fd, CHRDEV1, 0)) + die("failure: delete"); + exit(EXIT_SUCCESS); } if (wait_for_pid(pid)) @@ -8266,9 +8438,12 @@ static int setgid_create_idmapped_in_userns(void) exit(EXIT_SUCCESS); } - if (!switch_userns(attr.userns_fd, 0, 1000, true)) + if (!switch_userns(attr.userns_fd, 0, 1000, false)) die("failure: switch_userns"); + if (!caps_down_fsetid()) + die("failure: caps_down_fsetid"); + /* create regular file via open() */ file1_fd = openat(open_tree_fd, FILE1, O_CREAT | O_EXCL | O_CLOEXEC, S_IXGRP | S_ISGID); if (file1_fd < 0) @@ -8295,12 +8470,44 @@ static int setgid_create_idmapped_in_userns(void) die("failure: is_setgid"); } + /* create a special file via mknodat() vfs_create */ + if (mknodat(open_tree_fd, FILE2, S_IFREG | S_ISGID | S_IXGRP, 0)) + die("failure: mknodat"); + + if (is_setgid(open_tree_fd, FILE2, 0)) + die("failure: is_setgid"); + + /* create a whiteout device via mknodat() vfs_mknod */ + if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0)) + die("failure: mknodat"); + + if (is_setgid(open_tree_fd, CHRDEV1, 0)) + die("failure: is_setgid"); + if (!expected_uid_gid(open_tree_fd, FILE1, 0, 0, 0)) die("failure: check ownership"); if (!expected_uid_gid(open_tree_fd, DIR1, 0, 0, 0)) die("failure: check ownership"); + if (!expected_uid_gid(open_tree_fd, FILE2, 0, 0, 0)) + die("failure: check ownership"); + + if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 0)) + die("failure: check ownership"); + + if (unlinkat(open_tree_fd, FILE1, 0)) + die("failure: delete"); + + if (unlinkat(open_tree_fd, DIR1, AT_REMOVEDIR)) + die("failure: delete"); + + if (unlinkat(open_tree_fd, FILE2, 0)) + die("failure: delete"); + + if (unlinkat(open_tree_fd, CHRDEV1, 0)) + die("failure: delete"); + exit(EXIT_SUCCESS); } if (wait_for_pid(pid))
Since mknodat can create file, we should also check whether strip S_ISGID. Also add new helper caps_down_fsetid to drop CAP_FSETID because strip S_ISGID depend on this cap and keep other cap(ie CAP_MKNOD) because create character device needs it when using mknod. Only test mknodat with character device in setgid_create function and the another two functions test mknodat with whiteout device. Since kernel commit a3c751a50 ("vfs: allow unprivileged whiteout creation") in v5.8-rc1, we can create whiteout device in userns test. Since kernel 5.12, mount_setattr and MOUNT_ATTR_IDMAP was supported, we don't need to detect kernel whether allow unprivileged whiteout creation. Using fs_allow_idmap as a proxy is safe. Tested-by: Christian Brauner (Microsoft)<brauner@kernel.org> Reviewed-by: Christian Brauner (Microsoft)<brauner@kernel.org> Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com> --- src/idmapped-mounts/idmapped-mounts.c | 219 +++++++++++++++++++++++++- 1 file changed, 213 insertions(+), 6 deletions(-)