On Fri, Nov 04, 2022 at 02:43:25PM +0100, Roberto Sassu wrote: > On Thu, 2022-11-03 at 16:27 +0100, Roberto Sassu wrote: > > On Wed, 2022-10-26 at 16:30 +0200, Nicolas Bouchinet wrote: > > > From: Nicolas Bouchinet <nicolas.bouchinet@xxxxxxxxxxx> > > > > > > Fixes a NULL pointer dereference occurring in the > > > `evm_protected_xattr_common` function of the EVM LSM. The bug is > > > triggered if a `inode_init_security` hook returns 0 without initializing > > > the given `struct xattr` fields (which is the case of BPF) and if no > > > other LSM overrides thoses fields after. This also leads to memory > > > leaks. > > > > > > The `call_int_hook_xattr` macro has been inlined into the > > > `security_inode_init_security` hook in order to check hooks return > > > values and skip ones who doesn't init `xattrs`. > > > > > > Modify `evm_init_hmac` function to init the EVM hmac using every > > > entry of the given xattr array. > > > > > > The `MAX_LSM_EVM_XATTR` value is now based on the security modules > > > compiled in, which gives room for SMACK, SELinux, Apparmor, BPF and > > > IMA/EVM security attributes. > > > > > > Changes the default return value of the `inode_init_security` hook > > > definition to `-EOPNOTSUPP`. > > > > > > Changes the hook documentation to match the behavior of the LSMs using > > > it (only xattr->value is initialised with kmalloc and thus is the only > > > one that should be kfreed by the caller). > > > > > > Cc: roberto.sassu@xxxxxxxxxxxxxxx > > > Signed-off-by: Nicolas Bouchinet <nicolas.bouchinet@xxxxxxxxxxx> > > > --- > > > Changes since v3: > > > https://lore.kernel.org/linux-integrity/Y1fu4jofqLHVDprT@archlinux/ > > > > > > * Fixes compilation error reported by the kernel test robot. > > > --- > > > include/linux/lsm_hook_defs.h | 2 +- > > > include/linux/lsm_hooks.h | 4 ++-- > > > security/integrity/evm/evm.h | 1 + > > > security/integrity/evm/evm_crypto.c | 9 +++++++-- > > > security/integrity/evm/evm_main.c | 7 ++++--- > > > security/security.c | 31 ++++++++++++++++++++++------- > > > 6 files changed, 39 insertions(+), 15 deletions(-) > > > > > > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > > > index 806448173033..e5dd0c0f6345 100644 > > > --- a/include/linux/lsm_hook_defs.h > > > +++ b/include/linux/lsm_hook_defs.h > > > @@ -111,7 +111,7 @@ LSM_HOOK(int, 0, path_notify, const struct path *path, u64 mask, > > > unsigned int obj_type) > > > LSM_HOOK(int, 0, inode_alloc_security, struct inode *inode) > > > LSM_HOOK(void, LSM_RET_VOID, inode_free_security, struct inode *inode) > > > -LSM_HOOK(int, 0, inode_init_security, struct inode *inode, > > > +LSM_HOOK(int, -EOPNOTSUPP, inode_init_security, struct inode *inode, > > > struct inode *dir, const struct qstr *qstr, const char **name, > > > void **value, size_t *len) > > > LSM_HOOK(int, 0, inode_init_security_anon, struct inode *inode, > > > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h > > > index 84a0d7e02176..95aff9383de1 100644 > > > --- a/include/linux/lsm_hooks.h > > > +++ b/include/linux/lsm_hooks.h > > > @@ -229,8 +229,8 @@ > > > * This hook is called by the fs code as part of the inode creation > > > * transaction and provides for atomic labeling of the inode, unlike > > > * the post_create/mkdir/... hooks called by the VFS. The hook function > > > - * is expected to allocate the name and value via kmalloc, with the caller > > > - * being responsible for calling kfree after using them. > > > + * is expected to allocate the value via kmalloc, with the caller > > > + * being responsible for calling kfree after using it. > > > > Please also update the description of @name as well (remove allocated). > > While you update the patch, I worked on the other patches: reiserfs > fixes, if we want still to apply them; expand the call_int_hook() loop > also for security_old_inode_init_security() to have consistent behavior > across all filesystems. Thank's I didn't had time to read the patch, will do it. > > The patches are available here: > > https://github.com/robertosassu/linux/tree/evm-multiple-lsms-nicolas-v1-devel-v6 > > Other than Github Actions related patches, there is also TestLSM, which > I developed to ensure that xattrs are correctly created. > > I also adapted the IMA/EVM tests, which are available here: > > https://github.com/robertosassu/ima-evm-utils/tree/evm-multiple-lsms-nicolas-v1-devel-v6 > > Nicolas, if you want to test the new patch locally, build the UML > kernel with: Will surely do ! Thanks. > > make ARCH=um -j$(nproc) > > Build ima-evm-utils, and copy linux and certs/signing_key.pem from the > kernel source directory to the ima-evm-utils directory. Then, run: > > tests/evm_multiple_lsms.test > > It basically runs the UML kernel with different combinations of LSMs > (some providing an xattr, some not) and compares the HMAC calculated by > EVM in the kernel with the HMAC calculated by evmctl in user space. > > Roberto > Best regards, Nicolas Bouchinet
