Messages in this thread | | | Date | Tue, 31 May 2022 15:26:21 -0400 | Subject | Re: [PATCH v12 21/26] ima: Setup securityfs for IMA namespace | From | Stefan Berger <> |
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On 5/29/22 21:16, Serge E. Hallyn wrote: > On Wed, Apr 20, 2022 at 10:06:28AM -0400, Stefan Berger wrote: >> Setup securityfs with symlinks, directories, and files for IMA >> namespacing support. The same directory structure that IMA uses on the >> host is also created for the namespacing case. >> >> The securityfs file and directory ownerships cannot be set when the >> IMA namespace is initialized. Therefore, delay the setup of the file >> system to a later point when securityfs is in securityfs_fill_super. >> >> Introduce a variable ima_policy_removed in ima_namespace that is used to >> remember whether the policy file has previously been removed and thus >> should not be created again in case of unmounting and again mounting >> securityfs inside an IMA namespace. >> >> This filesystem can now be mounted as follows: >> >> mount -t securityfs /sys/kernel/security/ /sys/kernel/security/ >> >> The following directories, symlinks, and files are available >> when IMA namespacing is enabled, otherwise it will be empty: >> >> $ ls -l sys/kernel/security/ >> total 0 >> lr--r--r--. 1 root root 0 Dec 2 00:18 ima -> integrity/ima >> drwxr-xr-x. 3 root root 0 Dec 2 00:18 integrity >> >> $ ls -l sys/kernel/security/ima/ >> total 0 >> -r--r-----. 1 root root 0 Dec 2 00:18 ascii_runtime_measurements >> -r--r-----. 1 root root 0 Dec 2 00:18 binary_runtime_measurements >> -rw-------. 1 root root 0 Dec 2 00:18 policy >> -r--r-----. 1 root root 0 Dec 2 00:18 runtime_measurements_count >> -r--r-----. 1 root root 0 Dec 2 00:18 violations >> >> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com> >> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> >> Acked-by: Christian Brauner <brauner@kernel.org> >> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> > > Acked-by: Serge Hallyn <serge@hallyn.com> > > but a nit below
Thanks for all the tags, I took all of them. Would I need to worry about the other reviewerss' tags regardig the nit below? I'd rather leave it as-is otherwise.
Stefan
> >> >> --- >> >> v9: >> - rename policy_dentry_removed to ima_policy_removed >> --- >> include/linux/ima.h | 13 ++++++++++ >> security/inode.c | 6 ++++- >> security/integrity/ima/ima.h | 1 + >> security/integrity/ima/ima_fs.c | 46 +++++++++++++++++++++++---------- >> 4 files changed, 52 insertions(+), 14 deletions(-) >> >> diff --git a/include/linux/ima.h b/include/linux/ima.h >> index b9301e2aaa8b..0cbf0434bc93 100644 >> --- a/include/linux/ima.h >> +++ b/include/linux/ima.h >> @@ -41,6 +41,7 @@ extern int ima_measure_critical_data(const char *event_label, >> const char *event_name, >> const void *buf, size_t buf_len, >> bool hash, u8 *digest, size_t digest_len); >> +extern int ima_fs_ns_init(struct user_namespace *user_ns, struct dentry *root); >> >> #ifdef CONFIG_IMA_APPRAISE_BOOTPARAM >> extern void ima_appraise_parse_cmdline(void); >> @@ -227,6 +228,12 @@ void free_ima_ns(struct user_namespace *ns); >> >> void ima_free_ns_status_list(struct list_head *head, rwlock_t *ns_list_lock); >> >> +static inline int ima_securityfs_init(struct user_namespace *user_ns, >> + struct dentry *root) >> +{ >> + return ima_fs_ns_init(user_ns, root); >> +} >> + >> #else >> >> static inline void free_ima_ns(struct user_namespace *user_ns) >> @@ -238,6 +245,12 @@ static inline void ima_free_ns_status_list(struct list_head *head, >> { >> } >> >> +static inline int ima_securityfs_init(struct user_namespace *ns, >> + struct dentry *root) >> +{ >> + return 0; >> +} >> + >> #endif /* CONFIG_IMA_NS */ >> >> #endif /* _LINUX_IMA_H */ >> diff --git a/security/inode.c b/security/inode.c >> index 84c9396792a9..e81f55f054dc 100644 >> --- a/security/inode.c >> +++ b/security/inode.c >> @@ -16,6 +16,7 @@ >> #include <linux/fs_context.h> >> #include <linux/mount.h> >> #include <linux/pagemap.h> >> +#include <linux/ima.h> >> #include <linux/init.h> >> #include <linux/namei.h> >> #include <linux/security.h> >> @@ -82,7 +83,10 @@ static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc) >> sb->s_op = &securityfs_super_operations; >> sb->s_root->d_inode->i_op = &securityfs_dir_inode_operations; >> >> - return 0; >> + if (ns != &init_user_ns) >> + error = ima_securityfs_init(ns, sb->s_root); >> + >> + return error; >> } >> >> static int securityfs_get_tree(struct fs_context *fc) >> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h >> index cb48fc1d5b80..801dc3c8bfde 100644 >> --- a/security/integrity/ima/ima.h >> +++ b/security/integrity/ima/ima.h >> @@ -152,6 +152,7 @@ struct ima_namespace { >> int valid_policy; >> >> struct dentry *ima_policy; >> + bool ima_policy_removed; >> >> struct notifier_block ima_lsm_policy_notifier; >> } __randomize_layout; >> diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c >> index c41aa61b7393..84cd02a9e19b 100644 >> --- a/security/integrity/ima/ima_fs.c >> +++ b/security/integrity/ima/ima_fs.c >> @@ -21,6 +21,7 @@ >> #include <linux/rcupdate.h> >> #include <linux/parser.h> >> #include <linux/vmalloc.h> >> +#include <linux/ima.h> >> >> #include "ima.h" >> >> @@ -433,6 +434,7 @@ static int ima_release_policy(struct inode *inode, struct file *file) >> #if !defined(CONFIG_IMA_WRITE_POLICY) && !defined(CONFIG_IMA_READ_POLICY) >> securityfs_remove(ns->ima_policy); >> ns->ima_policy = NULL; >> + ns->ima_policy_removed = true; >> #elif defined(CONFIG_IMA_WRITE_POLICY) >> clear_bit(IMA_FS_BUSY, &ns->ima_fs_flags); >> #elif defined(CONFIG_IMA_READ_POLICY) >> @@ -449,9 +451,11 @@ static const struct file_operations ima_measure_policy_ops = { >> .llseek = generic_file_llseek, >> }; >> >> -static int __init ima_fs_ns_init(struct ima_namespace *ns) >> +int ima_fs_ns_init(struct user_namespace *user_ns, struct dentry *root) >> { >> - struct dentry *ima_dir; >> + struct ima_namespace *ns = ima_ns_from_user_ns(user_ns); >> + struct dentry *int_dir; >> + struct dentry *ima_dir = NULL; >> struct dentry *ima_symlink = NULL; >> struct dentry *binary_runtime_measurements = NULL; >> struct dentry *ascii_runtime_measurements = NULL; >> @@ -459,11 +463,22 @@ static int __init ima_fs_ns_init(struct ima_namespace *ns) >> struct dentry *violations = NULL; >> int ret; >> >> - ima_dir = securityfs_create_dir("ima", integrity_dir); >> - if (IS_ERR(ima_dir)) >> - return PTR_ERR(ima_dir); >> + /* FIXME: update when evm and integrity are namespaced */ >> + if (user_ns != &init_user_ns) { >> + int_dir = securityfs_create_dir("integrity", root); >> + if (IS_ERR(int_dir)) >> + return PTR_ERR(int_dir); >> + } else { >> + int_dir = integrity_dir; >> + } >> >> - ima_symlink = securityfs_create_symlink("ima", NULL, "integrity/ima", >> + ima_dir = securityfs_create_dir("ima", int_dir); >> + if (IS_ERR(ima_dir)) { >> + ret = PTR_ERR(ima_dir); >> + goto out; >> + } >> + >> + ima_symlink = securityfs_create_symlink("ima", root, "integrity/ima", >> NULL); >> if (IS_ERR(ima_symlink)) { >> ret = PTR_ERR(ima_symlink); >> @@ -505,12 +520,15 @@ static int __init ima_fs_ns_init(struct ima_namespace *ns) >> goto out; >> } >> >> - ns->ima_policy = securityfs_create_file("policy", POLICY_FILE_FLAGS, >> - ima_dir, NULL, >> - &ima_measure_policy_ops); >> - if (IS_ERR(ns->ima_policy)) { >> - ret = PTR_ERR(ns->ima_policy); >> - goto out; >> + if (!ns->ima_policy_removed) { > > It would be nicer to avoid this indent level by just doing > > if (ns->ima_policy_removed) > return 0; > > above the securityfs_create_file(). > >> + ns->ima_policy = >> + securityfs_create_file("policy", POLICY_FILE_FLAGS, >> + ima_dir, NULL, >> + &ima_measure_policy_ops); >> + if (IS_ERR(ns->ima_policy)) { >> + ret = PTR_ERR(ns->ima_policy); >> + goto out; >> + } >> } >> >> return 0; >> @@ -522,11 +540,13 @@ static int __init ima_fs_ns_init(struct ima_namespace *ns) >> securityfs_remove(binary_runtime_measurements); >> securityfs_remove(ima_symlink); >> securityfs_remove(ima_dir); >> + if (user_ns != &init_user_ns) >> + securityfs_remove(int_dir); >> >> return ret; >> } >> >> int __init ima_fs_init(void) >> { >> - return ima_fs_ns_init(&init_ima_ns); >> + return ima_fs_ns_init(&init_user_ns, NULL); >> } >> -- >> 2.34.1 >>
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