| Message ID | 20240711111908.3817636-3-xukuohai@huaweicloud.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Add return value range check for BPF LSM | expand |
Jul 11, 2024 06:14:09 Xu Kuohai <xukuohai@huaweicloud.com>: > From: Xu Kuohai <xukuohai@huawei.com> > > To be consistent with most LSM hooks, convert the return value of > hook inode_need_killpriv to 0 or a negative error code. > > Before: > - Both hook inode_need_killpriv and func security_inode_need_killpriv > return > 0 if security_inode_killpriv is required, 0 if not, and < 0 > to abort the operation. > > After: > - Both hook inode_need_killpriv and func security_inode_need_killpriv > return 0 on success and a negative error code on failure. > On success, hook inode_need_killpriv sets output param @need to true > if security_inode_killpriv is required, and false if not. When @need > is true, func security_inode_need_killpriv sets ATTR_KILL_PRIV flag > in @attr; when false, it clears the flag. > On failure, @need and @attr remains unchanged. > > Signed-off-by: Xu Kuohai <xukuohai@huawei.com> It looks ok - though unnecessary (I'm assuming a later patch works better with this) - , but I'd be more comfortable if it was documented that any callers of the need_killpriv hook must set need to false before calling. Or if the hooks set need to false at start. > --- > fs/attr.c | 5 ++--- > fs/inode.c | 4 +--- > include/linux/lsm_hook_defs.h | 2 +- > include/linux/security.h | 20 ++++++++++++++++---- > security/commoncap.c | 12 ++++++++---- > security/security.c | 29 ++++++++++++++++++++++++----- > 6 files changed, 52 insertions(+), 20 deletions(-) > > diff --git a/fs/attr.c b/fs/attr.c > index 960a310581eb..aaadc721c982 100644 > --- a/fs/attr.c > +++ b/fs/attr.c > @@ -427,11 +427,10 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry, > attr->ia_mtime = timestamp_truncate(attr->ia_mtime, inode); > > if (ia_valid & ATTR_KILL_PRIV) { > - error = security_inode_need_killpriv(dentry); > + error = security_inode_need_killpriv(dentry, &ia_valid); > if (error < 0) > return error; > - if (error == 0) > - ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV; > + attr->ia_valid = ia_valid; > } > > /* > diff --git a/fs/inode.c b/fs/inode.c > index 3a41f83a4ba5..cd335dc3a3bc 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -2012,11 +2012,9 @@ int dentry_needs_remove_privs(struct mnt_idmap *idmap, > return 0; > > mask = setattr_should_drop_suidgid(idmap, inode); > - ret = security_inode_need_killpriv(dentry); > + ret = security_inode_need_killpriv(dentry, &mask); > if (ret < 0) > return ret; > - if (ret) > - mask |= ATTR_KILL_PRIV; > return mask; > } > > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index e6e6f8473955..964849de424b 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -165,7 +165,7 @@ LSM_HOOK(int, 0, inode_remove_acl, struct mnt_idmap *idmap, > struct dentry *dentry, const char *acl_name) > LSM_HOOK(void, LSM_RET_VOID, inode_post_remove_acl, struct mnt_idmap *idmap, > struct dentry *dentry, const char *acl_name) > -LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry) > +LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry, bool *need) > LSM_HOOK(int, 0, inode_killpriv, struct mnt_idmap *idmap, > struct dentry *dentry) > LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct mnt_idmap *idmap, > diff --git a/include/linux/security.h b/include/linux/security.h > index 454f96307cb9..1614ef5b2dd2 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -161,7 +161,7 @@ int cap_inode_setxattr(struct dentry *dentry, const char *name, > const void *value, size_t size, int flags); > int cap_inode_removexattr(struct mnt_idmap *idmap, > struct dentry *dentry, const char *name); > -int cap_inode_need_killpriv(struct dentry *dentry); > +int cap_inode_need_killpriv(struct dentry *dentry, bool *need); > int cap_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry); > int cap_inode_getsecurity(struct mnt_idmap *idmap, > struct inode *inode, const char *name, void **buffer, > @@ -389,7 +389,7 @@ int security_inode_listxattr(struct dentry *dentry); > int security_inode_removexattr(struct mnt_idmap *idmap, > struct dentry *dentry, const char *name); > void security_inode_post_removexattr(struct dentry *dentry, const char *name); > -int security_inode_need_killpriv(struct dentry *dentry); > +int security_inode_need_killpriv(struct dentry *dentry, int *attr); > int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry); > int security_inode_getsecurity(struct mnt_idmap *idmap, > struct inode *inode, const char *name, > @@ -971,9 +971,21 @@ static inline void security_inode_post_removexattr(struct dentry *dentry, > const char *name) > { } > > -static inline int security_inode_need_killpriv(struct dentry *dentry) > +static inline int security_inode_need_killpriv(struct dentry *dentry, int *attr) > { > - return cap_inode_need_killpriv(dentry); > + int rc; > + bool need = false; > + > + rc = cap_inode_need_killpriv(dentry, &need); > + if (rc < 0) > + return rc; > + > + if (need) > + *attr |= ATTR_KILL_PRIV; > + else > + *attr &= ~ATTR_KILL_PRIV; > + > + return 0; > } > > static inline int security_inode_killpriv(struct mnt_idmap *idmap, > diff --git a/security/commoncap.c b/security/commoncap.c > index cefad323a0b1..17d6188d22cf 100644 > --- a/security/commoncap.c > +++ b/security/commoncap.c > @@ -286,21 +286,25 @@ int cap_capset(struct cred *new, > /** > * cap_inode_need_killpriv - Determine if inode change affects privileges > * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV > + * @need: If inode_killpriv() is needed > * > * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV > * affects the security markings on that inode, and if it is, should > * inode_killpriv() be invoked or the change rejected. > * > - * Return: 1 if security.capability has a value, meaning inode_killpriv() > - * is required, 0 otherwise, meaning inode_killpriv() is not required. > + * Return: Always returns 0. If security.capability has a value, meaning > + * inode_killpriv() is required, @need is set to true. > */ > -int cap_inode_need_killpriv(struct dentry *dentry) > +int cap_inode_need_killpriv(struct dentry *dentry, bool *need) > { > struct inode *inode = d_backing_inode(dentry); > int error; > > error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0); > - return error > 0; > + if (error > 0) > + *need = true; > + > + return 0; > } > > /** > diff --git a/security/security.c b/security/security.c > index 3475f0cab3da..a4abcd86eb36 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -2490,17 +2490,36 @@ void security_inode_post_removexattr(struct dentry *dentry, const char *name) > /** > * security_inode_need_killpriv() - Check if security_inode_killpriv() required > * @dentry: associated dentry > + * @attr: attribute flags > * > * Called when an inode has been changed to determine if > * security_inode_killpriv() should be called. > * > - * Return: Return <0 on error to abort the inode change operation, return 0 if > - * security_inode_killpriv() does not need to be called, return >0 if > - * security_inode_killpriv() does need to be called. > + * Return: Return 0 on success, negative error code on failure. > + * On success, set ATTR_KILL_PRIV flag in @attr when @need is true, > + * clears it when false. > */ > -int security_inode_need_killpriv(struct dentry *dentry) > +int security_inode_need_killpriv(struct dentry *dentry, int *attr) > { > - return call_int_hook(inode_need_killpriv, dentry); > + int rc; > + bool need = false; > + struct security_hook_list *hp; > + > + hlist_for_each_entry(hp, &security_hook_heads.inode_need_killpriv, > + list) { > + rc = hp->hook.inode_need_killpriv(dentry, &need); > + if (rc < 0) > + return rc; > + if (need) > + break; > + } > + > + if (need) > + *attr |= ATTR_KILL_PRIV; > + else > + *attr &= ~ATTR_KILL_PRIV; > + > + return 0; > } > > /** > -- > 2.30.2
On 7/11/2024 10:15 PM, Serge Hallyn wrote: > Jul 11, 2024 06:14:09 Xu Kuohai <xukuohai@huaweicloud.com>: > >> From: Xu Kuohai <xukuohai@huawei.com> >> >> To be consistent with most LSM hooks, convert the return value of >> hook inode_need_killpriv to 0 or a negative error code. >> >> Before: >> - Both hook inode_need_killpriv and func security_inode_need_killpriv >> return > 0 if security_inode_killpriv is required, 0 if not, and < 0 >> to abort the operation. >> >> After: >> - Both hook inode_need_killpriv and func security_inode_need_killpriv >> return 0 on success and a negative error code on failure. >> On success, hook inode_need_killpriv sets output param @need to true >> if security_inode_killpriv is required, and false if not. When @need >> is true, func security_inode_need_killpriv sets ATTR_KILL_PRIV flag >> in @attr; when false, it clears the flag. >> On failure, @need and @attr remains unchanged. >> >> Signed-off-by: Xu Kuohai <xukuohai@huawei.com> > > It looks ok - though unnecessary (I'm assuming a later patch works better with this) - , but I'd be more comfortable if it was documented that any callers of the need_killpriv hook must set need to false before calling. Or if the hooks set need to false at start. > > I believe this is the only patch in the set that modifies 'inode_need_killpriv'. I'll add an explanation for the initial value of '@need'. Thanks.
On Jul 11, 2024 Xu Kuohai <xukuohai@huaweicloud.com> wrote: > > To be consistent with most LSM hooks, convert the return value of > hook inode_need_killpriv to 0 or a negative error code. > > Before: > - Both hook inode_need_killpriv and func security_inode_need_killpriv > return > 0 if security_inode_killpriv is required, 0 if not, and < 0 > to abort the operation. > > After: > - Both hook inode_need_killpriv and func security_inode_need_killpriv > return 0 on success and a negative error code on failure. > On success, hook inode_need_killpriv sets output param @need to true > if security_inode_killpriv is required, and false if not. When @need > is true, func security_inode_need_killpriv sets ATTR_KILL_PRIV flag > in @attr; when false, it clears the flag. > On failure, @need and @attr remains unchanged. > > Signed-off-by: Xu Kuohai <xukuohai@huawei.com> > --- > fs/attr.c | 5 ++--- > fs/inode.c | 4 +--- > include/linux/lsm_hook_defs.h | 2 +- > include/linux/security.h | 20 ++++++++++++++++---- > security/commoncap.c | 12 ++++++++---- > security/security.c | 29 ++++++++++++++++++++++++----- > 6 files changed, 52 insertions(+), 20 deletions(-) In general I think a lot of these changes are a good improvement, thank you very much for the time and effort you've spent on this. However, I'm not in favor of passing the new hook parameter as a way of reducing the number of states represented by the security_inode_killpriv() return value. This particular hook may need to remain as one of the odd special cases. > diff --git a/fs/attr.c b/fs/attr.c > index 960a310581eb..aaadc721c982 100644 > --- a/fs/attr.c > +++ b/fs/attr.c > @@ -427,11 +427,10 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry, > attr->ia_mtime = timestamp_truncate(attr->ia_mtime, inode); > > if (ia_valid & ATTR_KILL_PRIV) { > - error = security_inode_need_killpriv(dentry); > + error = security_inode_need_killpriv(dentry, &ia_valid); > if (error < 0) > return error; > - if (error == 0) > - ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV; > + attr->ia_valid = ia_valid; > } > > /* > diff --git a/fs/inode.c b/fs/inode.c > index 3a41f83a4ba5..cd335dc3a3bc 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -2012,11 +2012,9 @@ int dentry_needs_remove_privs(struct mnt_idmap *idmap, > return 0; > > mask = setattr_should_drop_suidgid(idmap, inode); > - ret = security_inode_need_killpriv(dentry); > + ret = security_inode_need_killpriv(dentry, &mask); > if (ret < 0) > return ret; > - if (ret) > - mask |= ATTR_KILL_PRIV; > return mask; > } > > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index e6e6f8473955..964849de424b 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -165,7 +165,7 @@ LSM_HOOK(int, 0, inode_remove_acl, struct mnt_idmap *idmap, > struct dentry *dentry, const char *acl_name) > LSM_HOOK(void, LSM_RET_VOID, inode_post_remove_acl, struct mnt_idmap *idmap, > struct dentry *dentry, const char *acl_name) > -LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry) > +LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry, bool *need) > LSM_HOOK(int, 0, inode_killpriv, struct mnt_idmap *idmap, > struct dentry *dentry) > LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct mnt_idmap *idmap, > diff --git a/include/linux/security.h b/include/linux/security.h > index 454f96307cb9..1614ef5b2dd2 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -161,7 +161,7 @@ int cap_inode_setxattr(struct dentry *dentry, const char *name, > const void *value, size_t size, int flags); > int cap_inode_removexattr(struct mnt_idmap *idmap, > struct dentry *dentry, const char *name); > -int cap_inode_need_killpriv(struct dentry *dentry); > +int cap_inode_need_killpriv(struct dentry *dentry, bool *need); > int cap_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry); > int cap_inode_getsecurity(struct mnt_idmap *idmap, > struct inode *inode, const char *name, void **buffer, > @@ -389,7 +389,7 @@ int security_inode_listxattr(struct dentry *dentry); > int security_inode_removexattr(struct mnt_idmap *idmap, > struct dentry *dentry, const char *name); > void security_inode_post_removexattr(struct dentry *dentry, const char *name); > -int security_inode_need_killpriv(struct dentry *dentry); > +int security_inode_need_killpriv(struct dentry *dentry, int *attr); > int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry); > int security_inode_getsecurity(struct mnt_idmap *idmap, > struct inode *inode, const char *name, > @@ -971,9 +971,21 @@ static inline void security_inode_post_removexattr(struct dentry *dentry, > const char *name) > { } > > -static inline int security_inode_need_killpriv(struct dentry *dentry) > +static inline int security_inode_need_killpriv(struct dentry *dentry, int *attr) > { > - return cap_inode_need_killpriv(dentry); > + int rc; > + bool need = false; > + > + rc = cap_inode_need_killpriv(dentry, &need); > + if (rc < 0) > + return rc; > + > + if (need) > + *attr |= ATTR_KILL_PRIV; > + else > + *attr &= ~ATTR_KILL_PRIV; > + > + return 0; > } > > static inline int security_inode_killpriv(struct mnt_idmap *idmap, > diff --git a/security/commoncap.c b/security/commoncap.c > index cefad323a0b1..17d6188d22cf 100644 > --- a/security/commoncap.c > +++ b/security/commoncap.c > @@ -286,21 +286,25 @@ int cap_capset(struct cred *new, > /** > * cap_inode_need_killpriv - Determine if inode change affects privileges > * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV > + * @need: If inode_killpriv() is needed > * > * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV > * affects the security markings on that inode, and if it is, should > * inode_killpriv() be invoked or the change rejected. > * > - * Return: 1 if security.capability has a value, meaning inode_killpriv() > - * is required, 0 otherwise, meaning inode_killpriv() is not required. > + * Return: Always returns 0. If security.capability has a value, meaning > + * inode_killpriv() is required, @need is set to true. > */ > -int cap_inode_need_killpriv(struct dentry *dentry) > +int cap_inode_need_killpriv(struct dentry *dentry, bool *need) > { > struct inode *inode = d_backing_inode(dentry); > int error; > > error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0); > - return error > 0; > + if (error > 0) > + *need = true; > + > + return 0; > } > > /** > diff --git a/security/security.c b/security/security.c > index 3475f0cab3da..a4abcd86eb36 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -2490,17 +2490,36 @@ void security_inode_post_removexattr(struct dentry *dentry, const char *name) > /** > * security_inode_need_killpriv() - Check if security_inode_killpriv() required > * @dentry: associated dentry > + * @attr: attribute flags > * > * Called when an inode has been changed to determine if > * security_inode_killpriv() should be called. > * > - * Return: Return <0 on error to abort the inode change operation, return 0 if > - * security_inode_killpriv() does not need to be called, return >0 if > - * security_inode_killpriv() does need to be called. > + * Return: Return 0 on success, negative error code on failure. > + * On success, set ATTR_KILL_PRIV flag in @attr when @need is true, > + * clears it when false. > */ > -int security_inode_need_killpriv(struct dentry *dentry) > +int security_inode_need_killpriv(struct dentry *dentry, int *attr) > { > - return call_int_hook(inode_need_killpriv, dentry); > + int rc; > + bool need = false; > + struct security_hook_list *hp; > + > + hlist_for_each_entry(hp, &security_hook_heads.inode_need_killpriv, > + list) { > + rc = hp->hook.inode_need_killpriv(dentry, &need); > + if (rc < 0) > + return rc; > + if (need) > + break; > + } > + > + if (need) > + *attr |= ATTR_KILL_PRIV; > + else > + *attr &= ~ATTR_KILL_PRIV; > + > + return 0; > } > > /** > -- > 2.30.2 -- paul-moore.com
On 7/19/2024 10:08 AM, Paul Moore wrote: > On Jul 11, 2024 Xu Kuohai <xukuohai@huaweicloud.com> wrote: >> >> To be consistent with most LSM hooks, convert the return value of >> hook inode_need_killpriv to 0 or a negative error code. >> >> Before: >> - Both hook inode_need_killpriv and func security_inode_need_killpriv >> return > 0 if security_inode_killpriv is required, 0 if not, and < 0 >> to abort the operation. >> >> After: >> - Both hook inode_need_killpriv and func security_inode_need_killpriv >> return 0 on success and a negative error code on failure. >> On success, hook inode_need_killpriv sets output param @need to true >> if security_inode_killpriv is required, and false if not. When @need >> is true, func security_inode_need_killpriv sets ATTR_KILL_PRIV flag >> in @attr; when false, it clears the flag. >> On failure, @need and @attr remains unchanged. >> >> Signed-off-by: Xu Kuohai <xukuohai@huawei.com> >> --- >> fs/attr.c | 5 ++--- >> fs/inode.c | 4 +--- >> include/linux/lsm_hook_defs.h | 2 +- >> include/linux/security.h | 20 ++++++++++++++++---- >> security/commoncap.c | 12 ++++++++---- >> security/security.c | 29 ++++++++++++++++++++++++----- >> 6 files changed, 52 insertions(+), 20 deletions(-) > > In general I think a lot of these changes are a good improvement, thank > you very much for the time and effort you've spent on this. However, > I'm not in favor of passing the new hook parameter as a way of reducing > the number of states represented by the security_inode_killpriv() return > value. This particular hook may need to remain as one of the odd special > cases. > I learned from previous discussions [1] to use a new output parameter to store odd return values. Actually, I am not in favor of this method either, especially since it requires extra work to enable BPF to access the output parameter. I think we could just keep it as-is. [1] https://lore.kernel.org/bpf/CAHC9VhQ_sTmoXwQ_AVfjTYQe4KR-uTnksPVfsei5JZ+VDJBQkA@mail.gmail.com/
diff --git a/fs/attr.c b/fs/attr.c index 960a310581eb..aaadc721c982 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -427,11 +427,10 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry, attr->ia_mtime = timestamp_truncate(attr->ia_mtime, inode); if (ia_valid & ATTR_KILL_PRIV) { - error = security_inode_need_killpriv(dentry); + error = security_inode_need_killpriv(dentry, &ia_valid); if (error < 0) return error; - if (error == 0) - ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV; + attr->ia_valid = ia_valid; } /* diff --git a/fs/inode.c b/fs/inode.c index 3a41f83a4ba5..cd335dc3a3bc 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -2012,11 +2012,9 @@ int dentry_needs_remove_privs(struct mnt_idmap *idmap, return 0; mask = setattr_should_drop_suidgid(idmap, inode); - ret = security_inode_need_killpriv(dentry); + ret = security_inode_need_killpriv(dentry, &mask); if (ret < 0) return ret; - if (ret) - mask |= ATTR_KILL_PRIV; return mask; } diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index e6e6f8473955..964849de424b 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -165,7 +165,7 @@ LSM_HOOK(int, 0, inode_remove_acl, struct mnt_idmap *idmap, struct dentry *dentry, const char *acl_name) LSM_HOOK(void, LSM_RET_VOID, inode_post_remove_acl, struct mnt_idmap *idmap, struct dentry *dentry, const char *acl_name) -LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry) +LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry, bool *need) LSM_HOOK(int, 0, inode_killpriv, struct mnt_idmap *idmap, struct dentry *dentry) LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct mnt_idmap *idmap, diff --git a/include/linux/security.h b/include/linux/security.h index 454f96307cb9..1614ef5b2dd2 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -161,7 +161,7 @@ int cap_inode_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags); int cap_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, const char *name); -int cap_inode_need_killpriv(struct dentry *dentry); +int cap_inode_need_killpriv(struct dentry *dentry, bool *need); int cap_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry); int cap_inode_getsecurity(struct mnt_idmap *idmap, struct inode *inode, const char *name, void **buffer, @@ -389,7 +389,7 @@ int security_inode_listxattr(struct dentry *dentry); int security_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, const char *name); void security_inode_post_removexattr(struct dentry *dentry, const char *name); -int security_inode_need_killpriv(struct dentry *dentry); +int security_inode_need_killpriv(struct dentry *dentry, int *attr); int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry); int security_inode_getsecurity(struct mnt_idmap *idmap, struct inode *inode, const char *name, @@ -971,9 +971,21 @@ static inline void security_inode_post_removexattr(struct dentry *dentry, const char *name) { } -static inline int security_inode_need_killpriv(struct dentry *dentry) +static inline int security_inode_need_killpriv(struct dentry *dentry, int *attr) { - return cap_inode_need_killpriv(dentry); + int rc; + bool need = false; + + rc = cap_inode_need_killpriv(dentry, &need); + if (rc < 0) + return rc; + + if (need) + *attr |= ATTR_KILL_PRIV; + else + *attr &= ~ATTR_KILL_PRIV; + + return 0; } static inline int security_inode_killpriv(struct mnt_idmap *idmap, diff --git a/security/commoncap.c b/security/commoncap.c index cefad323a0b1..17d6188d22cf 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -286,21 +286,25 @@ int cap_capset(struct cred *new, /** * cap_inode_need_killpriv - Determine if inode change affects privileges * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV + * @need: If inode_killpriv() is needed * * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV * affects the security markings on that inode, and if it is, should * inode_killpriv() be invoked or the change rejected. * - * Return: 1 if security.capability has a value, meaning inode_killpriv() - * is required, 0 otherwise, meaning inode_killpriv() is not required. + * Return: Always returns 0. If security.capability has a value, meaning + * inode_killpriv() is required, @need is set to true. */ -int cap_inode_need_killpriv(struct dentry *dentry) +int cap_inode_need_killpriv(struct dentry *dentry, bool *need) { struct inode *inode = d_backing_inode(dentry); int error; error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0); - return error > 0; + if (error > 0) + *need = true; + + return 0; } /** diff --git a/security/security.c b/security/security.c index 3475f0cab3da..a4abcd86eb36 100644 --- a/security/security.c +++ b/security/security.c @@ -2490,17 +2490,36 @@ void security_inode_post_removexattr(struct dentry *dentry, const char *name) /** * security_inode_need_killpriv() - Check if security_inode_killpriv() required * @dentry: associated dentry + * @attr: attribute flags * * Called when an inode has been changed to determine if * security_inode_killpriv() should be called. * - * Return: Return <0 on error to abort the inode change operation, return 0 if - * security_inode_killpriv() does not need to be called, return >0 if - * security_inode_killpriv() does need to be called. + * Return: Return 0 on success, negative error code on failure. + * On success, set ATTR_KILL_PRIV flag in @attr when @need is true, + * clears it when false. */ -int security_inode_need_killpriv(struct dentry *dentry) +int security_inode_need_killpriv(struct dentry *dentry, int *attr) { - return call_int_hook(inode_need_killpriv, dentry); + int rc; + bool need = false; + struct security_hook_list *hp; + + hlist_for_each_entry(hp, &security_hook_heads.inode_need_killpriv, + list) { + rc = hp->hook.inode_need_killpriv(dentry, &need); + if (rc < 0) + return rc; + if (need) + break; + } + + if (need) + *attr |= ATTR_KILL_PRIV; + else + *attr &= ~ATTR_KILL_PRIV; + + return 0; } /**