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| author | Christian Brauner <brauner@kernel.org> | 2022-06-21 16:14:53 +0200 |
|---|---|---|
| committer | Christian Brauner (Microsoft) <brauner@kernel.org> | 2022-06-26 18:18:56 +0200 |
| commit | 0e363cf3fa598c69340794da068d4d9cbc869322 (patch) | |
| tree | a1b1b648f6cb3f9b09a41c44b0f3c8c2a3e17422 /fs | |
| parent | 71e7b535b8900d7ce7d5279fa472711db5251ae5 (diff) | |
| download | linux-0e363cf3fa598c69340794da068d4d9cbc869322.tar.gz linux-0e363cf3fa598c69340794da068d4d9cbc869322.tar.bz2 linux-0e363cf3fa598c69340794da068d4d9cbc869322.zip | |
security: pass down mount idmapping to setattr hook
Before this change we used to take a shortcut and place the actual
values that would be written to inode->i_{g,u}id into struct iattr. This
had the advantage that we moved idmappings mostly out of the picture
early on but it made reasoning about changes more difficult than it
should be.
The filesystem was never explicitly told that it dealt with an idmapped
mount. The transition to the value that needed to be stored in
inode->i_{g,u}id appeared way too early and increased the probability of
bugs in various codepaths.
We know place the same value in struct iattr no matter if this is an
idmapped mount or not. The vfs will only deal with type safe
vfs{g,u}id_t. This makes it massively safer to perform permission checks
as the type will tell us what checks we need to perform and what helpers
we need to use.
Adapt the security_inode_setattr() helper to pass down the mount's
idmapping to account for that change.
Link: https://lore.kernel.org/r/20220621141454.2914719-8-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/attr.c | 2 | ||||
| -rw-r--r-- | fs/fat/file.c | 3 |
2 files changed, 3 insertions, 2 deletions
diff --git a/fs/attr.c b/fs/attr.c index 2e180dd9460f..88e2ca30d42e 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -411,7 +411,7 @@ int notify_change(struct user_namespace *mnt_userns, struct dentry *dentry, !gid_valid(i_gid_into_mnt(mnt_userns, inode))) return -EOVERFLOW; - error = security_inode_setattr(dentry, attr); + error = security_inode_setattr(&init_user_ns, dentry, attr); if (error) return error; error = try_break_deleg(inode, delegated_inode); diff --git a/fs/fat/file.c b/fs/fat/file.c index 3dae3ed60f3a..530f18173db2 100644 --- a/fs/fat/file.c +++ b/fs/fat/file.c @@ -90,7 +90,8 @@ static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr) * out the RO attribute for checking by the security * module, just because it maps to a file mode. */ - err = security_inode_setattr(file->f_path.dentry, &ia); + err = security_inode_setattr(&init_user_ns, + file->f_path.dentry, &ia); if (err) goto out_unlock_inode; |