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author | Casey Schaufler <casey@schaufler-ca.com> | 2021-05-21 11:21:16 -0700 |
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committer | Paul Moore <paul@paul-moore.com> | 2021-09-19 22:40:51 -0400 |
commit | d9d8c93938c40e12de91650d04fceb99d92dad8a (patch) | |
tree | 9b47eec297d798926b22e80ce894e23890bd41e9 /security/smack | |
parent | 740b03414b20e7f1879cd99aae27d8c401bbcbf9 (diff) | |
download | linux-d9d8c93938c40e12de91650d04fceb99d92dad8a.tar.bz2 |
Smack: Brutalist io_uring support
Add Smack privilege checks for io_uring. Use CAP_MAC_OVERRIDE
for the override_creds case and CAP_MAC_ADMIN for creating a
polling thread. These choices are based on conjecture regarding
the intent of the surrounding code.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: make the smack_uring_* funcs static, remove debug code]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'security/smack')
-rw-r--r-- | security/smack/smack_lsm.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index cacbe7518519..f90ab1efeb6d 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -4691,6 +4691,48 @@ static int smack_dentry_create_files_as(struct dentry *dentry, int mode, return 0; } +#ifdef CONFIG_IO_URING +/** + * smack_uring_override_creds - Is io_uring cred override allowed? + * @new: the target creds + * + * Check to see if the current task is allowed to override it's credentials + * to service an io_uring operation. + */ +static int smack_uring_override_creds(const struct cred *new) +{ + struct task_smack *tsp = smack_cred(current_cred()); + struct task_smack *nsp = smack_cred(new); + + /* + * Allow the degenerate case where the new Smack value is + * the same as the current Smack value. + */ + if (tsp->smk_task == nsp->smk_task) + return 0; + + if (smack_privileged_cred(CAP_MAC_OVERRIDE, current_cred())) + return 0; + + return -EPERM; +} + +/** + * smack_uring_sqpoll - check if a io_uring polling thread can be created + * + * Check to see if the current task is allowed to create a new io_uring + * kernel polling thread. + */ +static int smack_uring_sqpoll(void) +{ + if (smack_privileged_cred(CAP_MAC_ADMIN, current_cred())) + return 0; + + return -EPERM; +} + +#endif /* CONFIG_IO_URING */ + struct lsm_blob_sizes smack_blob_sizes __lsm_ro_after_init = { .lbs_cred = sizeof(struct task_smack), .lbs_file = sizeof(struct smack_known *), @@ -4843,6 +4885,10 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(inode_copy_up, smack_inode_copy_up), LSM_HOOK_INIT(inode_copy_up_xattr, smack_inode_copy_up_xattr), LSM_HOOK_INIT(dentry_create_files_as, smack_dentry_create_files_as), +#ifdef CONFIG_IO_URING + LSM_HOOK_INIT(uring_override_creds, smack_uring_override_creds), + LSM_HOOK_INIT(uring_sqpoll, smack_uring_sqpoll), +#endif }; |