[PATCH v6 03/10] ipc: segment key change helper introduced
This patch introduces existent segment key changing infrastructure. New function ipc_update_key() can be used change segment key, cuid, cgid values. It checks for that new key is not used (except IPC_PRIVATE) prior to set it on existent. To make this possible, added copying of this fields from user-space in __get_compat_ipc_perm() and __get_compat_ipc64_perm() functions. Also segment search by key and lock were splitted into different functions, because ipc_update_key() doesn't need to lock the segment during check that new key is not used. Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> --- ipc/compat.c | 6 ++++++ ipc/util.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++--- ipc/util.h | 2 ++ 3 files changed, 56 insertions(+), 3 deletions(-) diff --git a/ipc/compat.c b/ipc/compat.c index ad9518e..af30d13 100644 --- a/ipc/compat.c +++ b/ipc/compat.c @@ -144,6 +144,9 @@ static inline int __get_compat_ipc64_perm(struct ipc64_perm *p64, err = __get_user(p64->uid, &up64->uid); err |= __get_user(p64->gid, &up64->gid); err |= __get_user(p64->mode, &up64->mode); + err |= __get_user(p64->cuid, &up64->cuid); + err |= __get_user(p64->cgid, &up64->cgid); + err |= __get_user(p64->key, &up64->key); return err; } @@ -155,6 +158,9 @@ static inline int __get_compat_ipc_perm(struct ipc64_perm *p, err = __get_user(p->uid, &up->uid); err |= __get_user(p->gid, &up->gid); err |= __get_user(p->mode, &up->mode); + err |= __get_user(p->cuid, &up->cuid); + err |= __get_user(p->cgid, &up->cgid); + err |= __get_user(p->key, &up->key); return err; } diff --git a/ipc/util.c b/ipc/util.c index 503946e..faae296 100644 --- a/ipc/util.c +++ b/ipc/util.c @@ -173,7 +173,7 @@ void __init ipc_init_proc_interface(const char *path, const char *header, * @key: The key to find * * Requires ipc_ids.rw_mutex locked. - * Returns the LOCKED pointer to the ipc structure if found or NULL + * Returns the UNLOCKED pointer to the ipc structure if found or NULL * if not. * If key is found ipc points to the owning ipc structure */ @@ -195,7 +195,6 @@ static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) continue; } - ipc_lock_by_ptr(ipc); return ipc; } @@ -203,6 +202,27 @@ static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) } /** + * ipc_findkey_locked - find and lock a key in an ipc identifier set + * @ids: Identifier set + * @key: The key to find + * + * Requires ipc_ids.rw_mutex locked. + * Returns the LOCKED pointer to the ipc structure if found or NULL + * if not. + * If key is found ipc points to the owning ipc structure + */ + +static struct kern_ipc_perm *ipc_findkey_locked(struct ipc_ids *ids, key_t key) +{ + struct kern_ipc_perm *ipc; + + ipc = ipc_findkey(ids, key); + if (ipc) + ipc_lock_by_ptr(ipc); + return ipc; +} + +/** * ipc_get_maxid - get the last assigned id * @ids: IPC identifier set * @@ -388,7 +408,7 @@ retry: * a new entry + read locks are not "upgradable" */ down_write(&ids->rw_mutex); - ipcp = ipc_findkey(ids, params->key); + ipcp = ipc_findkey_locked(ids, params->key); if (ipcp == NULL) { /* key not used */ if (!(flg & IPC_CREAT)) @@ -755,6 +775,31 @@ int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, } /** + * ipc_update_key - update the key of an IPC. + * @in: the permission given as input. + * @out: the permission of the ipc to set. + * + * Common routine called by sys_shmctl(), sys_semctl(). sys_msgctl(). + */ +int ipc_update_key(struct ipc_ids *ids, struct ipc64_perm *in, + struct kern_ipc_perm *out) +{ + + if (in->key && out->key != in->key) { + /* + * Check for existent segment with the same key. + * Note: ipc_ids.rw_mutex is taken for write already. + */ + if (ipc_findkey(ids, in->key)) + return -EEXIST; + } + out->cuid = in->cuid; + out->cgid = in->cgid; + out->key = in->key; + return 0; +} + +/** * ipc_update_perm - update the permissions of an IPC. * @in: the permission given as input. * @out: the permission of the ipc to set. diff --git a/ipc/util.h b/ipc/util.h index 3a9e558..271bded 100644 --- a/ipc/util.h +++ b/ipc/util.h @@ -126,6 +126,8 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out); +int ipc_update_key(struct ipc_ids *ids, struct ipc64_perm *in, + struct kern_ipc_perm *out); int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out); struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns, struct ipc_ids *ids, int id, int cmd,
Re: [PATCH v6 03/10] ipc: segment key change helper introduced
Quoting Stanislav Kinsbursky (skinsbursky@parallels.com): > This patch introduces existent segment key changing infrastructure. > New function ipc_update_key() can be used change segment key, cuid, cgid > values. It checks for that new key is not used (except IPC_PRIVATE) prior to > set it on existent. > To make this possible, added copying of this fields from user-space in > __get_compat_ipc_perm() and __get_compat_ipc64_perm() functions. Also segment > search by key and lock were splitted into different functions, because > ipc_update_key() doesn't need to lock the segment during check that new key is > not used. > > Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> > --- > ipc/compat.c | 6 ++++++ > ipc/util.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++--- > ipc/util.h | 2 ++ > 3 files changed, 56 insertions(+), 3 deletions(-) > > diff --git a/ipc/compat.c b/ipc/compat.c > index ad9518e..af30d13 100644 > --- a/ipc/compat.c > +++ b/ipc/compat.c > @@ -144,6 +144,9 @@ static inline int __get_compat_ipc64_perm(struct ipc64_perm *p64, > err = __get_user(p64->uid, &up64->uid); > err |= __get_user(p64->gid, &up64->gid); > err |= __get_user(p64->mode, &up64->mode); > + err |= __get_user(p64->cuid, &up64->cuid); > + err |= __get_user(p64->cgid, &up64->cgid); > + err |= __get_user(p64->key, &up64->key); > return err; > } > > @@ -155,6 +158,9 @@ static inline int __get_compat_ipc_perm(struct ipc64_perm *p, > err = __get_user(p->uid, &up->uid); > err |= __get_user(p->gid, &up->gid); > err |= __get_user(p->mode, &up->mode); > + err |= __get_user(p->cuid, &up->cuid); > + err |= __get_user(p->cgid, &up->cgid); > + err |= __get_user(p->key, &up->key); > return err; > } > > diff --git a/ipc/util.c b/ipc/util.c > index 503946e..faae296 100644 > --- a/ipc/util.c > +++ b/ipc/util.c > @@ -173,7 +173,7 @@ void __init ipc_init_proc_interface(const char *path, const char *header, > * @key: The key to find > * > * Requires ipc_ids.rw_mutex locked. > - * Returns the LOCKED pointer to the ipc structure if found or NULL > + * Returns the UNLOCKED pointer to the ipc structure if found or NULL > * if not. > * If key is found ipc points to the owning ipc structure > */ > @@ -195,7 +195,6 @@ static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) > continue; > } > > - ipc_lock_by_ptr(ipc); > return ipc; > } > > @@ -203,6 +202,27 @@ static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) > } > > /** > + * ipc_findkey_locked - find and lock a key in an ipc identifier set > + * @ids: Identifier set > + * @key: The key to find > + * > + * Requires ipc_ids.rw_mutex locked. > + * Returns the LOCKED pointer to the ipc structure if found or NULL > + * if not. > + * If key is found ipc points to the owning ipc structure > + */ > + > +static struct kern_ipc_perm *ipc_findkey_locked(struct ipc_ids *ids, key_t key) > +{ > + struct kern_ipc_perm *ipc; > + > + ipc = ipc_findkey(ids, key); > + if (ipc) > + ipc_lock_by_ptr(ipc); > + return ipc; > +} > + > +/** > * ipc_get_maxid - get the last assigned id > * @ids: IPC identifier set > * > @@ -388,7 +408,7 @@ retry: > * a new entry + read locks are not "upgradable" > */ > down_write(&ids->rw_mutex); > - ipcp = ipc_findkey(ids, params->key); > + ipcp = ipc_findkey_locked(ids, params->key); > if (ipcp == NULL) { > /* key not used */ > if (!(flg & IPC_CREAT)) > @@ -755,6 +775,31 @@ int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, > } > > /** > + * ipc_update_key - update the key of an IPC. > + * @in: the permission given as input. > + * @out: the permission of the ipc to set. > + * > + * Common routine called by sys_shmctl(), sys_semctl(). sys_msgctl(). > + */ > +int ipc_update_key(struct ipc_ids *ids, struct ipc64_perm *in, > + struct kern_ipc_perm *out) > +{ > + > + if (in->key && out->key != in->key) { > + /* > + * Check for existent segment with the same key. > + * Note: ipc_ids.rw_mutex is taken for write already. > + */ > + if (ipc_findkey(ids, in->key)) > + return -EEXIST; > + } > + out->cuid = in->cuid; > + out->cgid = in->cgid; > + out->key = in->key; > + return 0; > +} > + > +/** > * ipc_update_perm - update the permissions of an IPC. > * @in: the permission given as input. > * @out: the permission of the ipc to set. > diff --git a/ipc/util.h b/ipc/util.h > index 3a9e558..271bded 100644 > --- a/ipc/util.h > +++ b/ipc/util.h > @@ -126,6 +126,8 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); > > void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); > void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out); > +int ipc_update_key(struct ipc_ids *ids, struct ipc64_perm *in, > + struct kern_ipc_perm *out); > int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out); > struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns, > struct ipc_ids *ids, int id, int cmd, > > -- > To unsubscribe from this list: send the line "unsubscribe linux-security-module" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html