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authorMimi Zohar <zohar@linux.ibm.com>2023-12-18 16:06:40 +0300
committerMimi Zohar <zohar@linux.ibm.com>2023-12-20 15:40:07 +0300
commitcd708c938f055c9eb5a366ec1c8edcefa28afc28 (patch)
tree39089292c344413f5243377e57f993057a0f52e9 /security/integrity/evm
parent40ca4ee3136d2d09977d1cab8c0c0e1582c3359d (diff)
downloadlinux-cd708c938f055c9eb5a366ec1c8edcefa28afc28.tar.xz
evm: add support to disable EVM on unsupported filesystems
Identify EVM unsupported filesystems by defining a new flag SB_I_EVM_UNSUPPORTED. Don't verify, write, remove or update 'security.evm' on unsupported filesystems. Acked-by: Amir Goldstein <amir73il@gmail.com> Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Diffstat (limited to 'security/integrity/evm')
-rw-r--r--security/integrity/evm/evm_main.c35
1 files changed, 34 insertions, 1 deletions
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 02adba635b02..cc7956d7878b 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -151,6 +151,17 @@ static int evm_find_protected_xattrs(struct dentry *dentry)
return count;
}
+static int is_unsupported_fs(struct dentry *dentry)
+{
+ struct inode *inode = d_backing_inode(dentry);
+
+ if (inode->i_sb->s_iflags & SB_I_EVM_UNSUPPORTED) {
+ pr_info_once("%s not supported\n", inode->i_sb->s_type->name);
+ return 1;
+ }
+ return 0;
+}
+
/*
* evm_verify_hmac - calculate and compare the HMAC with the EVM xattr
*
@@ -181,6 +192,9 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
iint->evm_status == INTEGRITY_PASS_IMMUTABLE))
return iint->evm_status;
+ if (is_unsupported_fs(dentry))
+ return INTEGRITY_UNKNOWN;
+
/* if status is not PASS, try to check again - against -ENOMEM */
/* first need to know the sig type */
@@ -408,6 +422,9 @@ enum integrity_status evm_verifyxattr(struct dentry *dentry,
if (!evm_key_loaded() || !evm_protected_xattr(xattr_name))
return INTEGRITY_UNKNOWN;
+ if (is_unsupported_fs(dentry))
+ return INTEGRITY_UNKNOWN;
+
if (!iint) {
iint = integrity_iint_find(d_backing_inode(dentry));
if (!iint)
@@ -491,15 +508,21 @@ static int evm_protect_xattr(struct mnt_idmap *idmap,
if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
+ if (is_unsupported_fs(dentry))
+ return -EPERM;
} else if (!evm_protected_xattr(xattr_name)) {
if (!posix_xattr_acl(xattr_name))
return 0;
+ if (is_unsupported_fs(dentry))
+ return 0;
+
evm_status = evm_verify_current_integrity(dentry);
if ((evm_status == INTEGRITY_PASS) ||
(evm_status == INTEGRITY_NOXATTRS))
return 0;
goto out;
- }
+ } else if (is_unsupported_fs(dentry))
+ return 0;
evm_status = evm_verify_current_integrity(dentry);
if (evm_status == INTEGRITY_NOXATTRS) {
@@ -750,6 +773,9 @@ void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
if (!(evm_initialized & EVM_INIT_HMAC))
return;
+ if (is_unsupported_fs(dentry))
+ return;
+
evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len);
}
@@ -814,8 +840,12 @@ int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
return 0;
+ if (is_unsupported_fs(dentry))
+ return 0;
+
if (!(ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
return 0;
+
evm_status = evm_verify_current_integrity(dentry);
/*
* Writing attrs is safe for portable signatures, as portable signatures
@@ -859,6 +889,9 @@ void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
if (!(evm_initialized & EVM_INIT_HMAC))
return;
+ if (is_unsupported_fs(dentry))
+ return;
+
if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
evm_update_evmxattr(dentry, NULL, NULL, 0);
}