[RFC v1 07/14] krsi: Check for premissions on eBPF attachment
From: KP Singh <hidden>
Date: 2019-09-10 11:56:40
Also in:
bpf, lkml
Subsystem:
security subsystem, the rest · Maintainers:
Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
From: KP Singh <redacted> Add validation checks for the attachment of eBPF programs. The following permissions are required: - CAP_SYS_ADMIN to load eBPF programs - CAP_MAC_ADMIN (to update the policy of an LSM) - The securityfs file being a KRSI hook and writable (O_RDWR) Signed-off-by: KP Singh <redacted> --- security/krsi/ops.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)
diff --git a/security/krsi/ops.c b/security/krsi/ops.c
index cf4d06189aa1..a61508b7018f 100644
--- a/security/krsi/ops.c
+++ b/security/krsi/ops.c@@ -23,11 +23,31 @@ static struct krsi_hook *get_hook_from_fd(int fd) goto error; } + /* + * Only CAP_MAC_ADMIN users are allowed to make + * changes to LSM hooks + */ + if (!capable(CAP_MAC_ADMIN)) { + ret = -EPERM; + goto error; + } + if (!is_krsi_hook_file(f.file)) { ret = -EINVAL; goto error; } + /* + * It's wrong to attach the program to the hook + * if the file is not opened for a write. Note that, + * this is an EBADF and not an EPERM because the file + * has been opened with an incorrect mode. + */ + if (!(f.file->f_mode & FMODE_WRITE)) { + ret = -EBADF; + goto error; + } + /* * The securityfs dentry never disappears, so we don't need to take a * reference to it.
--
2.20.1