From: Casey Schaufler casey@schaufler-ca.com
[ Upstream commit ecff30575b5ad0eda149aadad247b7f75411fd47 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- security/security.c | 17 +++++++++++++++-- security/selinux/hooks.c | 5 ++--- 2 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/security/security.c b/security/security.c index cf6615b5e820..745a8bf66d91 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 93eac9464c5f..69b0709bd156 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2916,10 +2916,9 @@ 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; }