lkml.org 
[lkml]   [2022]   [Jul]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v13 11/26] ima: Define mac_admin_ns_capable() as a wrapper for ns_capable()
    Date
    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.

    Cc: Alexander Viro <viro@zeniv.linux.org.uk>
    Cc: linux-fsdevel@vger.kernel.org
    Signed-off-by: Denis Semakin <denis.semakin@huawei.com>
    Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

    ---
    v13:
    - implemented file_sb_user_ns(const struct file *); const is needed so it
    can be called with seq_file's 'const struct file *file'

    v11:
    - use ns_capable_noaudit for CAP_MAC_ADMIN to avoid auditing in this case
    ---
    include/linux/capability.h | 6 ++++++
    include/linux/fs.h | 5 +++++
    security/integrity/ima/ima.h | 6 ++++++
    security/integrity/ima/ima_fs.c | 5 ++++-
    4 files changed, 21 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/include/linux/fs.h b/include/linux/fs.h
    index 9ad5e3520fae..a34b664ed3f1 100644
    --- a/include/linux/fs.h
    +++ b/include/linux/fs.h
    @@ -2595,6 +2595,11 @@ static inline struct user_namespace *file_mnt_user_ns(struct file *file)
    return mnt_user_ns(file->f_path.mnt);
    }

    +static inline struct user_namespace *file_sb_user_ns(const struct file *file)
    +{
    + return i_user_ns(file_inode(file));
    +}
    +
    /**
    * is_idmapped_mnt - check whether a mount is mapped
    * @mnt: the mount to check
    diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
    index 5bf7f080c2be..28a9842c566f 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_sb_user_ns(filp);
    +}
    +
    #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
    --
    2.36.1
    \
     
     \ /
      Last update: 2022-07-07 16:49    [W:3.720 / U:0.224 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site