[PATCH v12 11/26] ima: Define mac_admin_ns_capable() as a wrapper for ns_capable()
From: Stefan Berger <stefanb@linux.ibm.com>
Date: 2022-04-20 14:08:44
Also in:
linux-integrity, lkml
Subsystem:
capabilities, extended verification module (evm), integrity measurement architecture (ima), security subsystem, the rest · Maintainers:
Serge Hallyn, Mimi Zohar, Roberto Sassu, Dmitry Kasatkin, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
Define mac_admin_ns_capable() as a wrapper for the combined ns_capable() checks on CAP_MAC_ADMIN and CAP_SYS_ADMIN in a user namespace. Return true on the check if either capability or both are available. Use mac_admin_ns_capable() in place of capable(SYS_ADMIN). This will allow an IMA namespace to read the policy with only CAP_MAC_ADMIN, which has less privileges than CAP_SYS_ADMIN. Since CAP_MAC_ADMIN is an additional capability added to an existing gate avoid auditing in case it is not set. Signed-off-by: Denis Semakin <redacted> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com> --- v11: - use ns_capable_noaudit for CAP_MAC_ADMIN to avoid auditing in this case --- include/linux/capability.h | 6 ++++++ security/integrity/ima/ima.h | 6 ++++++ security/integrity/ima/ima_fs.c | 5 ++++- 3 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 65efb74c3585..dc3e1230b365 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h@@ -270,6 +270,12 @@ static inline bool checkpoint_restore_ns_capable(struct user_namespace *ns) ns_capable(ns, CAP_SYS_ADMIN); } +static inline bool mac_admin_ns_capable(struct user_namespace *ns) +{ + return ns_capable_noaudit(ns, CAP_MAC_ADMIN) || + ns_capable(ns, CAP_SYS_ADMIN); +} + /* audit system wants to get cap info from files as well */ int get_vfs_caps_from_disk(struct user_namespace *mnt_userns, const struct dentry *dentry,
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 5bf7f080c2be..626a6ce2453c 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h@@ -491,4 +491,10 @@ static inline int ima_filter_rule_match(u32 secid, u32 field, u32 op, #define POLICY_FILE_FLAGS S_IWUSR #endif /* CONFIG_IMA_READ_POLICY */ +static inline +struct user_namespace *ima_user_ns_from_file(const struct file *filp) +{ + return file_inode(filp)->i_sb->s_user_ns; +} + #endif /* __LINUX_IMA_H */
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 89d3113ceda1..c41aa61b7393 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c@@ -377,6 +377,9 @@ static const struct seq_operations ima_policy_seqops = { */ static int ima_open_policy(struct inode *inode, struct file *filp) { +#ifdef CONFIG_IMA_READ_POLICY + struct user_namespace *user_ns = ima_user_ns_from_file(filp); +#endif struct ima_namespace *ns = &init_ima_ns; if (!(filp->f_flags & O_WRONLY)) {
@@ -385,7 +388,7 @@ static int ima_open_policy(struct inode *inode, struct file *filp) #else if ((filp->f_flags & O_ACCMODE) != O_RDONLY) return -EACCES; - if (!capable(CAP_SYS_ADMIN)) + if (!mac_admin_ns_capable(user_ns)) return -EPERM; return seq_open(filp, &ima_policy_seqops); #endif
--
2.34.1