diff options
| -rw-r--r-- | block/block-backend.c | 6 | ||||
| -rw-r--r-- | hmp.c | 26 | ||||
| -rw-r--r-- | include/qemu-io.h | 1 | ||||
| -rw-r--r-- | include/sysemu/block-backend.h | 1 | ||||
| -rw-r--r-- | qemu-io-cmds.c | 28 |
5 files changed, 61 insertions, 1 deletions
diff --git a/block/block-backend.c b/block/block-backend.c index 38a3858e96..daa7908d01 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -584,6 +584,12 @@ int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm, return 0; } +void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm) +{ + *perm = blk->perm; + *shared_perm = blk->shared_perm; +} + static int blk_do_attach_dev(BlockBackend *blk, void *dev) { if (blk->dev) { @@ -2051,7 +2051,6 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict) if (!blk) { BlockDriverState *bs = bdrv_lookup_bs(NULL, device, &err); if (bs) { - /* FIXME Use real permissions */ blk = local_blk = blk_new(0, BLK_PERM_ALL); ret = blk_insert_bs(blk, bs, &err); if (ret < 0) { @@ -2065,6 +2064,31 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict) aio_context = blk_get_aio_context(blk); aio_context_acquire(aio_context); + /* + * Notably absent: Proper permission management. This is sad, but it seems + * almost impossible to achieve without changing the semantics and thereby + * limiting the use cases of the qemu-io HMP command. + * + * In an ideal world we would unconditionally create a new BlockBackend for + * qemuio_command(), but we have commands like 'reopen' and want them to + * take effect on the exact BlockBackend whose name the user passed instead + * of just on a temporary copy of it. + * + * Another problem is that deleting the temporary BlockBackend involves + * draining all requests on it first, but some qemu-iotests cases want to + * issue multiple aio_read/write requests and expect them to complete in + * the background while the monitor has already returned. + * + * This is also what prevents us from saving the original permissions and + * restoring them later: We can't revoke permissions until all requests + * have completed, and we don't know when that is nor can we really let + * anything else run before we have revoken them to avoid race conditions. + * + * What happens now is that command() in qemu-io-cmds.c can extend the + * permissions if necessary for the qemu-io command. And they simply stay + * extended, possibly resulting in a read-only guest device keeping write + * permissions. Ugly, but it appears to be the lesser evil. + */ qemuio_command(blk, command); aio_context_release(aio_context); diff --git a/include/qemu-io.h b/include/qemu-io.h index 4d402b9b01..196fde0f3a 100644 --- a/include/qemu-io.h +++ b/include/qemu-io.h @@ -36,6 +36,7 @@ typedef struct cmdinfo { const char *args; const char *oneline; helpfunc_t help; + uint64_t perm; } cmdinfo_t; extern bool qemuio_misalign; diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h index b23f6830db..096c17fce0 100644 --- a/include/sysemu/block-backend.h +++ b/include/sysemu/block-backend.h @@ -107,6 +107,7 @@ bool bdrv_has_blk(BlockDriverState *bs); bool bdrv_is_root_node(BlockDriverState *bs); int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm, Error **errp); +void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm); void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow); void blk_iostatus_enable(BlockBackend *blk); diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c index 7ac1576d4c..2c48f9ce1a 100644 --- a/qemu-io-cmds.c +++ b/qemu-io-cmds.c @@ -83,6 +83,29 @@ static int command(BlockBackend *blk, const cmdinfo_t *ct, int argc, } return 0; } + + /* Request additional permissions if necessary for this command. The caller + * is responsible for restoring the original permissions afterwards if this + * is what it wants. */ + if (ct->perm && blk_is_available(blk)) { + uint64_t orig_perm, orig_shared_perm; + blk_get_perm(blk, &orig_perm, &orig_shared_perm); + + if (ct->perm & ~orig_perm) { + uint64_t new_perm; + Error *local_err = NULL; + int ret; + + new_perm = orig_perm | ct->perm; + + ret = blk_set_perm(blk, new_perm, orig_shared_perm, &local_err); + if (ret < 0) { + error_report_err(local_err); + return 0; + } + } + } + optind = 0; return ct->cfunc(blk, argc, argv); } @@ -918,6 +941,7 @@ static const cmdinfo_t write_cmd = { .name = "write", .altname = "w", .cfunc = write_f, + .perm = BLK_PERM_WRITE, .argmin = 2, .argmax = -1, .args = "[-bcCfquz] [-P pattern] off len", @@ -1093,6 +1117,7 @@ static int writev_f(BlockBackend *blk, int argc, char **argv); static const cmdinfo_t writev_cmd = { .name = "writev", .cfunc = writev_f, + .perm = BLK_PERM_WRITE, .argmin = 2, .argmax = -1, .args = "[-Cfq] [-P pattern] off len [len..]", @@ -1392,6 +1417,7 @@ static int aio_write_f(BlockBackend *blk, int argc, char **argv); static const cmdinfo_t aio_write_cmd = { .name = "aio_write", .cfunc = aio_write_f, + .perm = BLK_PERM_WRITE, .argmin = 2, .argmax = -1, .args = "[-Cfiquz] [-P pattern] off len [len..]", @@ -1556,6 +1582,7 @@ static const cmdinfo_t truncate_cmd = { .name = "truncate", .altname = "t", .cfunc = truncate_f, + .perm = BLK_PERM_WRITE | BLK_PERM_RESIZE, .argmin = 1, .argmax = 1, .args = "off", @@ -1653,6 +1680,7 @@ static const cmdinfo_t discard_cmd = { .name = "discard", .altname = "d", .cfunc = discard_f, + .perm = BLK_PERM_WRITE, .argmin = 2, .argmax = -1, .args = "[-Cq] off len", |