Re: [PATCH v4 3/20] lsm: Refactor return value of LSM hook inode_getsecurity
From: Paul Moore <paul@paul-moore.com>
Date: 2024-07-19 02:08:03
Also in:
bpf, linux-integrity, linux-kselftest, linux-security-module, selinux
On Jul 11, 2024 Xu Kuohai [off-list ref] wrote:
To be consistent with most LSM hooks, convert the return value of hook inode_getsecurity to 0 or a negative error code. Before: - Hook inode_getsecurity returns size of buffer on success or a negative error code on failure. After: - Hook inode_getsecurity returns 0 on success or a negative error code on failure. An output parameter @len is introduced to hold the buffer size on success. Signed-off-by: Xu Kuohai <redacted> --- fs/xattr.c | 19 ++++++++++--------- include/linux/lsm_hook_defs.h | 3 ++- include/linux/security.h | 12 ++++++------ security/commoncap.c | 9 ++++++--- security/security.c | 11 ++++++----- security/selinux/hooks.c | 16 ++++++---------- security/smack/smack_lsm.c | 14 +++++++------- 7 files changed, 43 insertions(+), 41 deletions(-)
Aside from Simon's concern over variable types, I saw a few other issues when looking at this patch (below).
quoted hunk ↗ jump to hunk
diff --git a/security/commoncap.c b/security/commoncap.c index 17d6188d22cf..ff82e2ab6f8f 100644 --- a/security/commoncap.c +++ b/security/commoncap.c@@ -485,7 +485,10 @@ int cap_inode_getsecurity(struct mnt_idmap *idmap, } out_free: kfree(tmpbuf); - return size; + if (size < 0) + return size; + *len = size; + return 0; }
We should do a better job converting cap_inode_getsecurity(), create a new local variable, e.g. 'int error', and use it to store and return the error code instead of reusing @size. I understand that what you've done is easier, but I'd prefer to see it done properly.
quoted hunk ↗ jump to hunk
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 9cd5a8f1f6a3..70792bba24d9 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c@@ -3407,7 +3407,7 @@ static int selinux_path_notify(const struct path *path, u64 mask, */ static int selinux_inode_getsecurity(struct mnt_idmap *idmap, struct inode *inode, const char *name, - void **buffer, bool alloc) + bool alloc, void **buffer, u32 *len) { u32 size; int error;@@ -3440,14 +3440,14 @@ static int selinux_inode_getsecurity(struct mnt_idmap *idmap, &context, &size); if (error) return error; - error = size; + *len = size;
Depending on how you choose to resolve the variable type issue, you may be able to pass @len directly to security_sid_to_context().
if (alloc) {
*buffer = context;
goto out_nofree;
}
kfree(context);
out_nofree:
- return error;
+ return 0;
}-- paul-moore.com