| Message ID | 20240429114636.123395-1-fuzhen5@huawei.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | BPF |
| Headers | show |
| Series | [-next] lsm: fix default return value for inode_set(remove)xattr | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Mon, Apr 29, 2024 at 7:47 AM felix <fuzhen5@huawei.com> wrote: > > From: Felix Fu <fuzhen5@huawei.com> > > The return value of security_inode_set(remove)xattr should > be 1. If it return 0, cap_inode_setxattr would not be > executed when no lsm exist, which is not what we expected, > any user could set some security.* xattr for a file. > > Before commit 260017f31a8c ("lsm: use default hook return > value in call_int_hook()") was approved, this issue would > still happened when lsm only include bpf, because bpf_lsm_ > inode_setxattr return 0 by default which cause cap_inode_set > xattr to be not executed. > > Fixes: 260017f31a8c ("lsm: use default hook return value in call_int_hook()") > Signed-off-by: Felix Fu <fuzhen5@huawei.com> > --- > include/linux/lsm_hook_defs.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) Adding the LSM list as that is the important list for this patch. I'm also just realizing we don't include lsm_hook_defs.h in the LSM MAINTAINERS entry, I'll submit a patch for that shortly. > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index f804b76cde44..9c768b954264 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -144,14 +144,14 @@ LSM_HOOK(int, 0, inode_setattr, struct mnt_idmap *idmap, struct dentry *dentry, > LSM_HOOK(void, LSM_RET_VOID, inode_post_setattr, struct mnt_idmap *idmap, > struct dentry *dentry, int ia_valid) > LSM_HOOK(int, 0, inode_getattr, const struct path *path) > -LSM_HOOK(int, 0, inode_setxattr, struct mnt_idmap *idmap, > +LSM_HOOK(int, 1, inode_setxattr, struct mnt_idmap *idmap, > struct dentry *dentry, const char *name, const void *value, > size_t size, int flags) > LSM_HOOK(void, LSM_RET_VOID, inode_post_setxattr, struct dentry *dentry, > const char *name, const void *value, size_t size, int flags) > LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name) > LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry) > -LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap, > +LSM_HOOK(int, 1, inode_removexattr, struct mnt_idmap *idmap, > struct dentry *dentry, const char *name) > LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry, > const char *name) > -- > 2.34.1
On Wed, May 1, 2024 at 12:02 PM Paul Moore <paul@paul-moore.com> wrote: > On Mon, Apr 29, 2024 at 7:47 AM felix <fuzhen5@huawei.com> wrote: > > > > From: Felix Fu <fuzhen5@huawei.com> > > > > The return value of security_inode_set(remove)xattr should > > be 1. If it return 0, cap_inode_setxattr would not be > > executed when no lsm exist, which is not what we expected, > > any user could set some security.* xattr for a file. > > > > Before commit 260017f31a8c ("lsm: use default hook return > > value in call_int_hook()") was approved, this issue would > > still happened when lsm only include bpf, because bpf_lsm_ > > inode_setxattr return 0 by default which cause cap_inode_set > > xattr to be not executed. > > > > Fixes: 260017f31a8c ("lsm: use default hook return value in call_int_hook()") > > Signed-off-by: Felix Fu <fuzhen5@huawei.com> > > --- > > include/linux/lsm_hook_defs.h | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > Adding the LSM list as that is the important list for this patch. It's also worth noting the discussion below from earlier this year. I just spent a little bit of time working on a different solution which I personally find more acceptable; I'm building a test kernel now, assuming it works I'll post it as a RFC. https://lore.kernel.org/linux-security-module/20240129133058.1627971-1-omosnace@redhat.com/
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index f804b76cde44..9c768b954264 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -144,14 +144,14 @@ LSM_HOOK(int, 0, inode_setattr, struct mnt_idmap *idmap, struct dentry *dentry, LSM_HOOK(void, LSM_RET_VOID, inode_post_setattr, struct mnt_idmap *idmap, struct dentry *dentry, int ia_valid) LSM_HOOK(int, 0, inode_getattr, const struct path *path) -LSM_HOOK(int, 0, inode_setxattr, struct mnt_idmap *idmap, +LSM_HOOK(int, 1, inode_setxattr, struct mnt_idmap *idmap, struct dentry *dentry, const char *name, const void *value, size_t size, int flags) LSM_HOOK(void, LSM_RET_VOID, inode_post_setxattr, struct dentry *dentry, const char *name, const void *value, size_t size, int flags) LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name) LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry) -LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap, +LSM_HOOK(int, 1, inode_removexattr, struct mnt_idmap *idmap, struct dentry *dentry, const char *name) LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry, const char *name)