Support the new fscaps security hooks by converting the vfs_caps to raw xattr data and then handling them the same as other xattrs.
Signed-off-by: Seth Forshee (DigitalOcean) <[email protected]> --- include/linux/evm.h | 39 +++++++++++++++++++++++++ security/integrity/evm/evm_main.c | 60 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 99 insertions(+) diff --git a/include/linux/evm.h b/include/linux/evm.h index 36ec884320d9..aeb9ff52ad22 100644 --- a/include/linux/evm.h +++ b/include/linux/evm.h @@ -57,6 +57,20 @@ static inline void evm_inode_post_set_acl(struct dentry *dentry, { return evm_inode_post_setxattr(dentry, acl_name, NULL, 0); } +extern int evm_inode_set_fscaps(struct mnt_idmap *idmap, + struct dentry *dentry, + const struct vfs_caps *caps, int flags); +static inline int evm_inode_remove_fscaps(struct dentry *dentry) +{ + return evm_inode_set_fscaps(&nop_mnt_idmap, dentry, NULL, XATTR_REPLACE); +} +extern void evm_inode_post_set_fscaps(struct mnt_idmap *idmap, + struct dentry *dentry, + const struct vfs_caps *caps, int flags); +static inline void evm_inode_post_remove_fscaps(struct dentry *dentry) +{ + return evm_inode_post_set_fscaps(&nop_mnt_idmap, dentry, NULL, 0); +} int evm_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, struct xattr *xattrs, @@ -164,6 +178,31 @@ static inline void evm_inode_post_set_acl(struct dentry *dentry, return; } +static inline int evm_inode_set_fscaps(struct mnt_idmap *idmap, + struct dentry *dentry, + const struct vfs_caps *caps, int flags) +{ + return 0; +} + +static inline int evm_inode_remove_fscaps(struct dentry *dentry) +{ + return 0; +} + +static inline void evm_inode_post_set_fscaps(struct mnt_idmap *idmap, + struct dentry *dentry, + const struct vfs_caps *caps, + int flags) +{ + return; +} + +static inline void evm_inode_post_remove_fscaps(struct dentry *dentry) +{ + return; +} + static inline int evm_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, struct xattr *xattrs, diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index cc7956d7878b..ecf4634a921a 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -805,6 +805,66 @@ void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name) evm_update_evmxattr(dentry, xattr_name, NULL, 0); } +int evm_inode_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + const struct vfs_caps *caps, int flags) +{ + struct inode *inode = d_inode(dentry); + struct vfs_ns_cap_data nscaps; + const void *xattr_data = NULL; + int size = 0; + + /* Policy permits modification of the protected xattrs even though + * there's no HMAC key loaded + */ + if (evm_initialized & EVM_ALLOW_METADATA_WRITES) + return 0; + + if (caps) { + size = vfs_caps_to_xattr(idmap, i_user_ns(inode), caps, &nscaps, + sizeof(nscaps)); + if (size < 0) + return size; + xattr_data = &nscaps; + } + + return evm_protect_xattr(idmap, dentry, XATTR_NAME_CAPS, xattr_data, size); +} + +void evm_inode_post_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + const struct vfs_caps *caps, int flags) +{ + struct inode *inode = d_inode(dentry); + struct vfs_ns_cap_data nscaps; + const void *xattr_data = NULL; + int size = 0; + + if (!evm_revalidate_status(XATTR_NAME_CAPS)) + return; + + evm_reset_status(dentry->d_inode); + + if (!(evm_initialized & EVM_INIT_HMAC)) + return; + + if (is_unsupported_fs(dentry)) + return; + + if (caps) { + size = vfs_caps_to_xattr(idmap, i_user_ns(inode), caps, &nscaps, + sizeof(nscaps)); + /* + * The fscaps here should have been converted to an xattr by + * evm_inode_set_fscaps() already, so a failure to convert + * here is a bug. + */ + if (WARN_ON_ONCE(size < 0)) + return; + xattr_data = &nscaps; + } + + evm_update_evmxattr(dentry, XATTR_NAME_CAPS, xattr_data, size); +} + static int evm_attr_change(struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr) { -- 2.43.0
