| Message ID | Y1K3bf+dtNnVe7DG@archlinux (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | [v2] evm: Correct inode_init_security hooks behaviors | expand |
On 10/21/2022 8:14 AM, Nicolas Bouchinet wrote: > From: Nicolas Bouchinet <nicolas.bouchinet@ssi.gouv.fr> > > 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. > > Adds a `call_int_hook_xattr` macro that fetches and feed the > `new_xattrs` array with every called hook xattr values. > > Adds a `evm_init_hmacs` function which init the EVM hmac using every > entry of the array contrary to `evm_init_hmac`. > > Fixes the `evm_inode_init_security` function to use `evm_init_hmacs`. > > The `MAX_LSM_EVM_XATTR` value has been raised to 5 which gives room for > SMACK, SELinux, Apparmor, BPF and IMA/EVM security attributes. This does not match the code, which sets the value based on the security modules compiled in rather than the constant 5. > > 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: stable@vger.kernel.org > Signed-off-by: Nicolas Bouchinet <nicolas.bouchinet@ssi.gouv.fr> > --- > > Changes since v1: > https://lore.kernel.org/linux-integrity/Y1FTSIo+1x+4X0LS@archlinux/ > * The `call_int_hook_xattr` macro has been inlined into the > `security_inode_init_security` hook (as suggested by Paul Moor, > Mickaël Salaün and Casey Schaufler). > * The MAX_LSM_EVM_XATTR value is processed based on compiled LSMs (as > proposed by Casey Schaufler). > * Various typos and cosmetic changes has been fixed (as suggested by > Mickaël Salaün) > * A MAX_LSM_EVM_XATTR test has been wrapped in a WAN_ON_ONCE macro (as > suggested by Mickaël Salaün). > --- > include/linux/lsm_hook_defs.h | 2 +- > include/linux/lsm_hooks.h | 4 ++-- > security/integrity/evm/evm.h | 2 ++ > security/integrity/evm/evm_crypto.c | 22 ++++++++++++++++++++++ > security/integrity/evm/evm_main.c | 9 +++++---- > security/security.c | 28 +++++++++++++++++++++------- > 6 files changed, 53 insertions(+), 14 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. > * If the security module does not use security attributes or does > * not wish to put a security attribute on this particular inode, > * then it should return -EOPNOTSUPP to skip this processing. > diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h > index f8b8c5004fc7..a2f9886e924d 100644 > --- a/security/integrity/evm/evm.h > +++ b/security/integrity/evm/evm.h > @@ -60,6 +60,8 @@ int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name, > struct evm_digest *data); > int evm_init_hmac(struct inode *inode, const struct xattr *xattr, > char *hmac_val); > +int evm_init_hmacs(struct inode *inode, const struct xattr *xattrs, > + char *hmac_val); > int evm_init_secfs(void); > > #endif > diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c > index 708de9656bbd..db6868875e09 100644 > --- a/security/integrity/evm/evm_crypto.c > +++ b/security/integrity/evm/evm_crypto.c > @@ -385,6 +385,28 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name, > return rc; > } > > +int evm_protected_xattr(const char *req_xattr_name); > + > +int evm_init_hmacs(struct inode *inode, const struct xattr *lsm_xattrs, > + char *hmac_val) > +{ > + struct shash_desc *desc; > + > + desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1); > + if (IS_ERR(desc)) { > + pr_info("init_desc failed\n"); > + return PTR_ERR(desc); > + } > + > + for (int i = 0; lsm_xattrs[i].value != NULL; i++) { > + if (evm_protected_xattr(lsm_xattrs[i].name)) > + crypto_shash_update(desc, lsm_xattrs[i].value, lsm_xattrs[i].value_len); > + } > + hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val); > + kfree(desc); > + return 0; > +} > + > int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr, > char *hmac_val) > { > diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c > index 2e6fb6e2ffd2..4f89b9eaf028 100644 > --- a/security/integrity/evm/evm_main.c > +++ b/security/integrity/evm/evm_main.c > @@ -284,6 +284,8 @@ static int evm_protected_xattr_common(const char *req_xattr_name, > int found = 0; > struct xattr_list *xattr; > > + if (!req_xattr_name) > + return found; > namelen = strlen(req_xattr_name); > list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) { > if (!all_xattrs && !xattr->enabled) > @@ -305,7 +307,7 @@ static int evm_protected_xattr_common(const char *req_xattr_name, > return found; > } > > -static int evm_protected_xattr(const char *req_xattr_name) > +int evm_protected_xattr(const char *req_xattr_name) > { > return evm_protected_xattr_common(req_xattr_name, false); > } > @@ -841,8 +843,7 @@ int evm_inode_init_security(struct inode *inode, > struct evm_xattr *xattr_data; > int rc; > > - if (!(evm_initialized & EVM_INIT_HMAC) || > - !evm_protected_xattr(lsm_xattr->name)) > + if (!(evm_initialized & EVM_INIT_HMAC)) > return 0; > > xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS); > @@ -850,7 +851,7 @@ int evm_inode_init_security(struct inode *inode, > return -ENOMEM; > > xattr_data->data.type = EVM_XATTR_HMAC; > - rc = evm_init_hmac(inode, lsm_xattr, xattr_data->digest); > + rc = evm_init_hmacs(inode, lsm_xattr, xattr_data->digest); > if (rc < 0) > goto out; > > diff --git a/security/security.c b/security/security.c > index 14d30fec8a00..cf11bd7d6a1b 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -30,7 +30,11 @@ > #include <linux/msg.h> > #include <net/flow.h> > > -#define MAX_LSM_EVM_XATTR 2 > +#define MAX_LSM_EVM_XATTR \ > + ((IS_ENABLED(CONFIG_EVM) ? 1 : 0) + \ > + (IS_ENABLED(CONFIG_SECURITY_SELINUX) ? 1 : 0) + \ > + (IS_ENABLED(CONFIG_SECURITY_SMACK) ? 1 : 0) + \ > + (IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0)) > > /* How many LSMs were built into the kernel? */ > #define LSM_COUNT (__end_lsm_info - __start_lsm_info) > @@ -1091,9 +1095,11 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, > const struct qstr *qstr, > const initxattrs initxattrs, void *fs_data) > { > + int i = 0; > + int ret = -EOPNOTSUPP; > struct xattr new_xattrs[MAX_LSM_EVM_XATTR + 1]; > struct xattr *lsm_xattr, *evm_xattr, *xattr; > - int ret; > + struct security_hook_list *hook_ptr; > > if (unlikely(IS_PRIVATE(inode))) > return 0; > @@ -1103,15 +1109,23 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, > dir, qstr, NULL, NULL, NULL); > memset(new_xattrs, 0, sizeof(new_xattrs)); > lsm_xattr = new_xattrs; > - ret = call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, qstr, > - &lsm_xattr->name, > - &lsm_xattr->value, > - &lsm_xattr->value_len); > + hlist_for_each_entry(hook_ptr, &security_hook_heads.inode_init_security, list) { > + ret = hook_ptr->hook.inode_init_security(inode, dir, qstr, &lsm_xattr->name, > + &lsm_xattr->value, &lsm_xattr->value_len); > + if (ret == -EOPNOTSUPP) > + continue; > + if (WARN_ON_ONCE(i >= MAX_LSM_EVM_XATTR)) > + ret = -ENOMEM; > + if (ret != 0) > + break; > + lsm_xattr++; > + i++; > + } > if (ret) > goto out; > > evm_xattr = lsm_xattr + 1; > - ret = evm_inode_init_security(inode, lsm_xattr, evm_xattr); > + ret = evm_inode_init_security(inode, new_xattrs, evm_xattr); > if (ret) > goto out; > ret = initxattrs(inode, new_xattrs, fs_data);
Hi Casey, thanks again for your time, On Fri, Oct 21, 2022 at 08:42:20AM -0700, Casey Schaufler wrote: > On 10/21/2022 8:14 AM, Nicolas Bouchinet wrote: > > From: Nicolas Bouchinet <nicolas.bouchinet@ssi.gouv.fr> > > > > 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. > > > > Adds a `call_int_hook_xattr` macro that fetches and feed the > > `new_xattrs` array with every called hook xattr values. > > > > Adds a `evm_init_hmacs` function which init the EVM hmac using every > > entry of the array contrary to `evm_init_hmac`. > > > > Fixes the `evm_inode_init_security` function to use `evm_init_hmacs`. > > > > The `MAX_LSM_EVM_XATTR` value has been raised to 5 which gives room for > > SMACK, SELinux, Apparmor, BPF and IMA/EVM security attributes. > > This does not match the code, which sets the value based on the > security modules compiled in rather than the constant 5. > Sorry for this, I think I will wait a day before sending patch v3. > > > > 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: stable@vger.kernel.org > > Signed-off-by: Nicolas Bouchinet <nicolas.bouchinet@ssi.gouv.fr> > > --- > > > > Changes since v1: > > https://lore.kernel.org/linux-integrity/Y1FTSIo+1x+4X0LS@archlinux/ > > * The `call_int_hook_xattr` macro has been inlined into the > > `security_inode_init_security` hook (as suggested by Paul Moor, > > Mickaël Salaün and Casey Schaufler). > > * The MAX_LSM_EVM_XATTR value is processed based on compiled LSMs (as > > proposed by Casey Schaufler). > > * Various typos and cosmetic changes has been fixed (as suggested by > > Mickaël Salaün) > > * A MAX_LSM_EVM_XATTR test has been wrapped in a WAN_ON_ONCE macro (as > > suggested by Mickaël Salaün). > > --- > > include/linux/lsm_hook_defs.h | 2 +- > > include/linux/lsm_hooks.h | 4 ++-- > > security/integrity/evm/evm.h | 2 ++ > > security/integrity/evm/evm_crypto.c | 22 ++++++++++++++++++++++ > > security/integrity/evm/evm_main.c | 9 +++++---- > > security/security.c | 28 +++++++++++++++++++++------- > > 6 files changed, 53 insertions(+), 14 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. > > * If the security module does not use security attributes or does > > * not wish to put a security attribute on this particular inode, > > * then it should return -EOPNOTSUPP to skip this processing. > > diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h > > index f8b8c5004fc7..a2f9886e924d 100644 > > --- a/security/integrity/evm/evm.h > > +++ b/security/integrity/evm/evm.h > > @@ -60,6 +60,8 @@ int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name, > > struct evm_digest *data); > > int evm_init_hmac(struct inode *inode, const struct xattr *xattr, > > char *hmac_val); > > +int evm_init_hmacs(struct inode *inode, const struct xattr *xattrs, > > + char *hmac_val); > > int evm_init_secfs(void); > > > > #endif > > diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c > > index 708de9656bbd..db6868875e09 100644 > > --- a/security/integrity/evm/evm_crypto.c > > +++ b/security/integrity/evm/evm_crypto.c > > @@ -385,6 +385,28 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name, > > return rc; > > } > > > > +int evm_protected_xattr(const char *req_xattr_name); > > + > > +int evm_init_hmacs(struct inode *inode, const struct xattr *lsm_xattrs, > > + char *hmac_val) > > +{ > > + struct shash_desc *desc; > > + > > + desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1); > > + if (IS_ERR(desc)) { > > + pr_info("init_desc failed\n"); > > + return PTR_ERR(desc); > > + } > > + > > + for (int i = 0; lsm_xattrs[i].value != NULL; i++) { > > + if (evm_protected_xattr(lsm_xattrs[i].name)) > > + crypto_shash_update(desc, lsm_xattrs[i].value, lsm_xattrs[i].value_len); > > + } > > + hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val); > > + kfree(desc); > > + return 0; > > +} > > + > > int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr, > > char *hmac_val) > > { > > diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c > > index 2e6fb6e2ffd2..4f89b9eaf028 100644 > > --- a/security/integrity/evm/evm_main.c > > +++ b/security/integrity/evm/evm_main.c > > @@ -284,6 +284,8 @@ static int evm_protected_xattr_common(const char *req_xattr_name, > > int found = 0; > > struct xattr_list *xattr; > > > > + if (!req_xattr_name) > > + return found; > > namelen = strlen(req_xattr_name); > > list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) { > > if (!all_xattrs && !xattr->enabled) > > @@ -305,7 +307,7 @@ static int evm_protected_xattr_common(const char *req_xattr_name, > > return found; > > } > > > > -static int evm_protected_xattr(const char *req_xattr_name) > > +int evm_protected_xattr(const char *req_xattr_name) > > { > > return evm_protected_xattr_common(req_xattr_name, false); > > } > > @@ -841,8 +843,7 @@ int evm_inode_init_security(struct inode *inode, > > struct evm_xattr *xattr_data; > > int rc; > > > > - if (!(evm_initialized & EVM_INIT_HMAC) || > > - !evm_protected_xattr(lsm_xattr->name)) > > + if (!(evm_initialized & EVM_INIT_HMAC)) > > return 0; > > > > xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS); > > @@ -850,7 +851,7 @@ int evm_inode_init_security(struct inode *inode, > > return -ENOMEM; > > > > xattr_data->data.type = EVM_XATTR_HMAC; > > - rc = evm_init_hmac(inode, lsm_xattr, xattr_data->digest); > > + rc = evm_init_hmacs(inode, lsm_xattr, xattr_data->digest); > > if (rc < 0) > > goto out; > > > > diff --git a/security/security.c b/security/security.c > > index 14d30fec8a00..cf11bd7d6a1b 100644 > > --- a/security/security.c > > +++ b/security/security.c > > @@ -30,7 +30,11 @@ > > #include <linux/msg.h> > > #include <net/flow.h> > > > > -#define MAX_LSM_EVM_XATTR 2 > > +#define MAX_LSM_EVM_XATTR \ > > + ((IS_ENABLED(CONFIG_EVM) ? 1 : 0) + \ > > + (IS_ENABLED(CONFIG_SECURITY_SELINUX) ? 1 : 0) + \ > > + (IS_ENABLED(CONFIG_SECURITY_SMACK) ? 1 : 0) + \ > > + (IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0)) > > > > /* How many LSMs were built into the kernel? */ > > #define LSM_COUNT (__end_lsm_info - __start_lsm_info) > > @@ -1091,9 +1095,11 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, > > const struct qstr *qstr, > > const initxattrs initxattrs, void *fs_data) > > { > > + int i = 0; > > + int ret = -EOPNOTSUPP; > > struct xattr new_xattrs[MAX_LSM_EVM_XATTR + 1]; > > struct xattr *lsm_xattr, *evm_xattr, *xattr; > > - int ret; > > + struct security_hook_list *hook_ptr; > > > > if (unlikely(IS_PRIVATE(inode))) > > return 0; > > @@ -1103,15 +1109,23 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, > > dir, qstr, NULL, NULL, NULL); > > memset(new_xattrs, 0, sizeof(new_xattrs)); > > lsm_xattr = new_xattrs; > > - ret = call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, qstr, > > - &lsm_xattr->name, > > - &lsm_xattr->value, > > - &lsm_xattr->value_len); > > + hlist_for_each_entry(hook_ptr, &security_hook_heads.inode_init_security, list) { > > + ret = hook_ptr->hook.inode_init_security(inode, dir, qstr, &lsm_xattr->name, > > + &lsm_xattr->value, &lsm_xattr->value_len); > > + if (ret == -EOPNOTSUPP) > > + continue; > > + if (WARN_ON_ONCE(i >= MAX_LSM_EVM_XATTR)) > > + ret = -ENOMEM; > > + if (ret != 0) > > + break; > > + lsm_xattr++; > > + i++; > > + } > > if (ret) > > goto out; > > > > evm_xattr = lsm_xattr + 1; > > - ret = evm_inode_init_security(inode, lsm_xattr, evm_xattr); > > + ret = evm_inode_init_security(inode, new_xattrs, evm_xattr); > > if (ret) > > goto out; > > ret = initxattrs(inode, new_xattrs, fs_data); Best regards, Nicolas Bouchinet
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. * If the security module does not use security attributes or does * not wish to put a security attribute on this particular inode, * then it should return -EOPNOTSUPP to skip this processing. diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h index f8b8c5004fc7..a2f9886e924d 100644 --- a/security/integrity/evm/evm.h +++ b/security/integrity/evm/evm.h @@ -60,6 +60,8 @@ int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name, struct evm_digest *data); int evm_init_hmac(struct inode *inode, const struct xattr *xattr, char *hmac_val); +int evm_init_hmacs(struct inode *inode, const struct xattr *xattrs, + char *hmac_val); int evm_init_secfs(void); #endif diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 708de9656bbd..db6868875e09 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -385,6 +385,28 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name, return rc; } +int evm_protected_xattr(const char *req_xattr_name); + +int evm_init_hmacs(struct inode *inode, const struct xattr *lsm_xattrs, + char *hmac_val) +{ + struct shash_desc *desc; + + desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1); + if (IS_ERR(desc)) { + pr_info("init_desc failed\n"); + return PTR_ERR(desc); + } + + for (int i = 0; lsm_xattrs[i].value != NULL; i++) { + if (evm_protected_xattr(lsm_xattrs[i].name)) + crypto_shash_update(desc, lsm_xattrs[i].value, lsm_xattrs[i].value_len); + } + hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val); + kfree(desc); + return 0; +} + int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr, char *hmac_val) { diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 2e6fb6e2ffd2..4f89b9eaf028 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -284,6 +284,8 @@ static int evm_protected_xattr_common(const char *req_xattr_name, int found = 0; struct xattr_list *xattr; + if (!req_xattr_name) + return found; namelen = strlen(req_xattr_name); list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) { if (!all_xattrs && !xattr->enabled) @@ -305,7 +307,7 @@ static int evm_protected_xattr_common(const char *req_xattr_name, return found; } -static int evm_protected_xattr(const char *req_xattr_name) +int evm_protected_xattr(const char *req_xattr_name) { return evm_protected_xattr_common(req_xattr_name, false); } @@ -841,8 +843,7 @@ int evm_inode_init_security(struct inode *inode, struct evm_xattr *xattr_data; int rc; - if (!(evm_initialized & EVM_INIT_HMAC) || - !evm_protected_xattr(lsm_xattr->name)) + if (!(evm_initialized & EVM_INIT_HMAC)) return 0; xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS); @@ -850,7 +851,7 @@ int evm_inode_init_security(struct inode *inode, return -ENOMEM; xattr_data->data.type = EVM_XATTR_HMAC; - rc = evm_init_hmac(inode, lsm_xattr, xattr_data->digest); + rc = evm_init_hmacs(inode, lsm_xattr, xattr_data->digest); if (rc < 0) goto out; diff --git a/security/security.c b/security/security.c index 14d30fec8a00..cf11bd7d6a1b 100644 --- a/security/security.c +++ b/security/security.c @@ -30,7 +30,11 @@ #include <linux/msg.h> #include <net/flow.h> -#define MAX_LSM_EVM_XATTR 2 +#define MAX_LSM_EVM_XATTR \ + ((IS_ENABLED(CONFIG_EVM) ? 1 : 0) + \ + (IS_ENABLED(CONFIG_SECURITY_SELINUX) ? 1 : 0) + \ + (IS_ENABLED(CONFIG_SECURITY_SMACK) ? 1 : 0) + \ + (IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0)) /* How many LSMs were built into the kernel? */ #define LSM_COUNT (__end_lsm_info - __start_lsm_info) @@ -1091,9 +1095,11 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, const initxattrs initxattrs, void *fs_data) { + int i = 0; + int ret = -EOPNOTSUPP; struct xattr new_xattrs[MAX_LSM_EVM_XATTR + 1]; struct xattr *lsm_xattr, *evm_xattr, *xattr; - int ret; + struct security_hook_list *hook_ptr; if (unlikely(IS_PRIVATE(inode))) return 0; @@ -1103,15 +1109,23 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, dir, qstr, NULL, NULL, NULL); memset(new_xattrs, 0, sizeof(new_xattrs)); lsm_xattr = new_xattrs; - ret = call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, qstr, - &lsm_xattr->name, - &lsm_xattr->value, - &lsm_xattr->value_len); + hlist_for_each_entry(hook_ptr, &security_hook_heads.inode_init_security, list) { + ret = hook_ptr->hook.inode_init_security(inode, dir, qstr, &lsm_xattr->name, + &lsm_xattr->value, &lsm_xattr->value_len); + if (ret == -EOPNOTSUPP) + continue; + if (WARN_ON_ONCE(i >= MAX_LSM_EVM_XATTR)) + ret = -ENOMEM; + if (ret != 0) + break; + lsm_xattr++; + i++; + } if (ret) goto out; evm_xattr = lsm_xattr + 1; - ret = evm_inode_init_security(inode, lsm_xattr, evm_xattr); + ret = evm_inode_init_security(inode, new_xattrs, evm_xattr); if (ret) goto out; ret = initxattrs(inode, new_xattrs, fs_data);