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authorCasey Schaufler <casey@schaufler-ca.com>2022-01-27 04:51:00 +0000
committerPaul Moore <paul@paul-moore.com>2022-01-27 20:43:02 -0500
commitecff30575b5ad0eda149aadad247b7f75411fd47 (patch)
tree5d8e8802ce75d4c3e43d7dd1a4c5d0c300e401a5 /security
parentcdeea45422f579b9302e377d1ede29133d3fde8e (diff)
LSM: general protection fault in legacy_parse_param
The usual LSM hook "bail on fail" scheme doesn't work for cases where a security module may return an error code indicating that it does not recognize an input. In this particular case Smack sees a mount option that it recognizes, and returns 0. A call to a BPF hook follows, which returns -ENOPARAM, which confuses the caller because Smack has processed its data. The SELinux hook incorrectly returns 1 on success. There was a time when this was correct, however the current expectation is that it return 0 on success. This is repaired. Reported-by: syzbot+d1e3b1d92d25abf97943@syzkaller.appspotmail.com Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'security')
-rw-r--r--security/security.c17
-rw-r--r--security/selinux/hooks.c5
2 files changed, 17 insertions, 5 deletions
diff --git a/security/security.c b/security/security.c
index 3d4eb474f35b..e649c8691be2 100644
--- a/security/security.c
+++ b/security/security.c
@@ -884,9 +884,22 @@ int security_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc)
return call_int_hook(fs_context_dup, 0, fc, src_fc);
}
-int security_fs_context_parse_param(struct fs_context *fc, struct fs_parameter *param)
+int security_fs_context_parse_param(struct fs_context *fc,
+ struct fs_parameter *param)
{
- return call_int_hook(fs_context_parse_param, -ENOPARAM, fc, param);
+ struct security_hook_list *hp;
+ int trc;
+ int rc = -ENOPARAM;
+
+ hlist_for_each_entry(hp, &security_hook_heads.fs_context_parse_param,
+ list) {
+ trc = hp->hook.fs_context_parse_param(fc, param);
+ if (trc == 0)
+ rc = 0;
+ else if (trc != -ENOPARAM)
+ return trc;
+ }
+ return rc;
}
int security_sb_alloc(struct super_block *sb)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 221e642025f5..9e3658e9e7ca 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2859,10 +2859,9 @@ static int selinux_fs_context_parse_param(struct fs_context *fc,
return opt;
rc = selinux_add_opt(opt, param->string, &fc->security);
- if (!rc) {
+ if (!rc)
param->string = NULL;
- rc = 1;
- }
+
return rc;
}