| Message ID | 20240403075729.2888084-1-roberto.sassu@huaweicloud.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] security: Place security_path_post_mknod() where the original IMA call was | expand |
On Wed, Apr 03, 2024 at 09:57:29AM +0200, Roberto Sassu wrote: > From: Roberto Sassu <roberto.sassu@huawei.com> > > Commit 08abce60d63f ("security: Introduce path_post_mknod hook") > introduced security_path_post_mknod(), to replace the IMA-specific call to > ima_post_path_mknod(). > > For symmetry with security_path_mknod(), security_path_post_mknod() was > called after a successful mknod operation, for any file type, rather than > only for regular files at the time there was the IMA call. > > However, as reported by VFS maintainers, successful mknod operation does > not mean that the dentry always has an inode attached to it (for example, > not for FIFOs on a SAMBA mount). > > If that condition happens, the kernel crashes when > security_path_post_mknod() attempts to verify if the inode associated to > the dentry is private. > > Move security_path_post_mknod() where the ima_post_path_mknod() call was, > which is obviously correct from IMA/EVM perspective. IMA/EVM are the only > in-kernel users, and only need to inspect regular files. > > Reported-by: Steve French <smfrench@gmail.com> > Closes: https://lore.kernel.org/linux-kernel/CAH2r5msAVzxCUHHG8VKrMPUKQHmBpE6K9_vjhgDa1uAvwx4ppw@mail.gmail.com/ > Suggested-by: Al Viro <viro@zeniv.linux.org.uk> > Fixes: 08abce60d63f ("security: Introduce path_post_mknod hook") > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > --- Reviewed-by: Christian Brauner <brauner@kernel.org>
On Wed, Apr 3, 2024 at 3:57 AM Roberto Sassu <roberto.sassu@huaweicloud.com> wrote: > > From: Roberto Sassu <roberto.sassu@huawei.com> > > Commit 08abce60d63f ("security: Introduce path_post_mknod hook") > introduced security_path_post_mknod(), to replace the IMA-specific call to > ima_post_path_mknod(). > > For symmetry with security_path_mknod(), security_path_post_mknod() was > called after a successful mknod operation, for any file type, rather than > only for regular files at the time there was the IMA call. > > However, as reported by VFS maintainers, successful mknod operation does > not mean that the dentry always has an inode attached to it (for example, > not for FIFOs on a SAMBA mount). > > If that condition happens, the kernel crashes when > security_path_post_mknod() attempts to verify if the inode associated to > the dentry is private. > > Move security_path_post_mknod() where the ima_post_path_mknod() call was, > which is obviously correct from IMA/EVM perspective. IMA/EVM are the only > in-kernel users, and only need to inspect regular files. > > Reported-by: Steve French <smfrench@gmail.com> > Closes: https://lore.kernel.org/linux-kernel/CAH2r5msAVzxCUHHG8VKrMPUKQHmBpE6K9_vjhgDa1uAvwx4ppw@mail.gmail.com/ > Suggested-by: Al Viro <viro@zeniv.linux.org.uk> > Fixes: 08abce60d63f ("security: Introduce path_post_mknod hook") > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > --- > fs/namei.c | 7 ++----- > security/security.c | 4 ++-- > 2 files changed, 4 insertions(+), 7 deletions(-) Acked-by: Paul Moore <paul@paul-moore.com>
diff --git a/fs/namei.c b/fs/namei.c index ceb9ddf8dfdd..c5b2a25be7d0 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -4050,6 +4050,8 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode, case 0: case S_IFREG: error = vfs_create(idmap, path.dentry->d_inode, dentry, mode, true); + if (!error) + security_path_post_mknod(idmap, dentry); break; case S_IFCHR: case S_IFBLK: error = vfs_mknod(idmap, path.dentry->d_inode, @@ -4060,11 +4062,6 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode, dentry, mode, 0); break; } - - if (error) - goto out2; - - security_path_post_mknod(idmap, dentry); out2: done_path_create(&path, dentry); if (retry_estale(error, lookup_flags)) { diff --git a/security/security.c b/security/security.c index 7e118858b545..0a9a0ac3f266 100644 --- a/security/security.c +++ b/security/security.c @@ -1793,11 +1793,11 @@ int security_path_mknod(const struct path *dir, struct dentry *dentry, EXPORT_SYMBOL(security_path_mknod); /** - * security_path_post_mknod() - Update inode security field after file creation + * security_path_post_mknod() - Update inode security after reg file creation * @idmap: idmap of the mount * @dentry: new file * - * Update inode security field after a file has been created. + * Update inode security field after a regular file has been created. */ void security_path_post_mknod(struct mnt_idmap *idmap, struct dentry *dentry) {