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 <skinsbur...@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 328abd1..1154245 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 878df18..b48016d 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); void 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, _______________________________________________ Devel mailing list Devel@openvz.org https://openvz.org/mailman/listinfo/devel