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Merged
cjihrig merged 1 commit into from
Jan 22, 2020
Merged

prevent locking fd table while holding a mutex #90

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9 changes: 8 additions & 1 deletion include/fd_table.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -46,17 +46,24 @@ uvwasi_errno_t uvwasi_fd_table_insert_preopen(struct uvwasi_s* uvwasi,
const uv_file fd,
const char* path,
const char* real_path);
uvwasi_errno_t uvwasi_fd_table_get(const struct uvwasi_fd_table_t* table,
uvwasi_errno_t uvwasi_fd_table_get(struct uvwasi_fd_table_t* table,
const uvwasi_fd_t id,
struct uvwasi_fd_wrap_t** wrap,
uvwasi_rights_t rights_base,
uvwasi_rights_t rights_inheriting);
uvwasi_errno_t uvwasi_fd_table_get_nolock(struct uvwasi_fd_table_t* table,
const uvwasi_fd_t id,
struct uvwasi_fd_wrap_t** wrap,
uvwasi_rights_t rights_base,
uvwasi_rights_t rights_inheriting);
uvwasi_errno_t uvwasi_fd_table_remove(struct uvwasi_s* uvwasi,
struct uvwasi_fd_table_t* table,
const uvwasi_fd_t id);
uvwasi_errno_t uvwasi_fd_table_renumber(struct uvwasi_s* uvwasi,
struct uvwasi_fd_table_t* table,
const uvwasi_fd_t dst,
const uvwasi_fd_t src);
uvwasi_errno_t uvwasi_fd_table_lock(struct uvwasi_fd_table_t* table);
uvwasi_errno_t uvwasi_fd_table_unlock(struct uvwasi_fd_table_t* table);

#endif /* __UVWASI_FD_TABLE_H__ */
67 changes: 49 additions & 18 deletions src/fd_table.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -252,44 +252,57 @@ uvwasi_errno_t uvwasi_fd_table_insert_preopen(uvwasi_t* uvwasi,
}


uvwasi_errno_t uvwasi_fd_table_get(const struct uvwasi_fd_table_t* table,
uvwasi_errno_t uvwasi_fd_table_get(struct uvwasi_fd_table_t* table,
const uvwasi_fd_t id,
struct uvwasi_fd_wrap_t** wrap,
uvwasi_rights_t rights_base,
uvwasi_rights_t rights_inheriting) {
struct uvwasi_fd_wrap_t* entry;
uvwasi_errno_t err;

if (table == NULL || wrap == NULL)
if (table == NULL)
return UVWASI_EINVAL;

uv_rwlock_rdlock((uv_rwlock_t *)&table->rwlock);
uv_rwlock_wrlock(&table->rwlock);
err = uvwasi_fd_table_get_nolock(table,
id,
wrap,
rights_base,
rights_inheriting);
uv_rwlock_wrunlock(&table->rwlock);
return err;
}

if (id >= table->size) {
err = UVWASI_EBADF;
goto exit;
}

/* uvwasi_fd_table_get_nolock() retrieves a file descriptor and locks its mutex,
but does not lock the file descriptor table like uvwasi_fd_table_get() does.
*/
uvwasi_errno_t uvwasi_fd_table_get_nolock(struct uvwasi_fd_table_t* table,
const uvwasi_fd_t id,
struct uvwasi_fd_wrap_t** wrap,
uvwasi_rights_t rights_base,
uvwasi_rights_t rights_inheriting) {
struct uvwasi_fd_wrap_t* entry;

if (table == NULL || wrap == NULL)
return UVWASI_EINVAL;

if (id >= table->size)
return UVWASI_EBADF;

entry = table->fds[id];

if (entry == NULL || entry->id != id) {
err = UVWASI_EBADF;
goto exit;
}
if (entry == NULL || entry->id != id)
return UVWASI_EBADF;

/* Validate that the fd has the necessary rights. */
if ((~entry->rights_base & rights_base) != 0 ||
(~entry->rights_inheriting & rights_inheriting) != 0) {
err = UVWASI_ENOTCAPABLE;
goto exit;
return UVWASI_ENOTCAPABLE;
}

uv_mutex_lock(&entry->mutex);
*wrap = entry;
err = UVWASI_ESUCCESS;
exit:
uv_rwlock_rdunlock((uv_rwlock_t *)&table->rwlock);
return err;
return UVWASI_ESUCCESS;
}


Expand Down Expand Up @@ -389,3 +402,21 @@ uvwasi_errno_t uvwasi_fd_table_renumber(struct uvwasi_s* uvwasi,
uv_rwlock_wrunlock(&table->rwlock);
return err;
}


uvwasi_errno_t uvwasi_fd_table_lock(struct uvwasi_fd_table_t* table) {
if (table == NULL)
return UVWASI_EINVAL;

uv_rwlock_wrlock(&table->rwlock);
return UVWASI_ESUCCESS;
}


uvwasi_errno_t uvwasi_fd_table_unlock(struct uvwasi_fd_table_t* table) {
if (table == NULL)
return UVWASI_EINVAL;

uv_rwlock_wrunlock(&table->rwlock);
return UVWASI_ESUCCESS;
}
106 changes: 56 additions & 50 deletions src/uvwasi.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1763,37 +1763,41 @@ uvwasi_errno_t uvwasi_path_link(uvwasi_t* uvwasi,
if (uvwasi == NULL || old_path == NULL || new_path == NULL)
return UVWASI_EINVAL;

if (old_fd == new_fd) {
err = uvwasi_fd_table_get(&uvwasi->fds,
old_fd,
&old_wrap,
UVWASI_RIGHT_PATH_LINK_SOURCE |
UVWASI_RIGHT_PATH_LINK_TARGET,
0);
if (err != UVWASI_ESUCCESS)
return err;
uvwasi_fd_table_lock(&uvwasi->fds);

if (old_fd == new_fd) {
err = uvwasi_fd_table_get_nolock(&uvwasi->fds,
old_fd,
&old_wrap,
UVWASI_RIGHT_PATH_LINK_SOURCE |
UVWASI_RIGHT_PATH_LINK_TARGET,
0);
new_wrap = old_wrap;
} else {
err = uvwasi_fd_table_get(&uvwasi->fds,
old_fd,
&old_wrap,
UVWASI_RIGHT_PATH_LINK_SOURCE,
0);
if (err != UVWASI_ESUCCESS)
return err;

err = uvwasi_fd_table_get(&uvwasi->fds,
new_fd,
&new_wrap,
UVWASI_RIGHT_PATH_LINK_TARGET,
0);
err = uvwasi_fd_table_get_nolock(&uvwasi->fds,
old_fd,
&old_wrap,
UVWASI_RIGHT_PATH_LINK_SOURCE,
0);
if (err != UVWASI_ESUCCESS) {
uv_mutex_unlock(&old_wrap->mutex);
uvwasi_fd_table_unlock(&uvwasi->fds);
return err;
}

err = uvwasi_fd_table_get_nolock(&uvwasi->fds,
new_fd,
&new_wrap,
UVWASI_RIGHT_PATH_LINK_TARGET,
0);
if (err != UVWASI_ESUCCESS)
uv_mutex_unlock(&old_wrap->mutex);
}

uvwasi_fd_table_unlock(&uvwasi->fds);

if (err != UVWASI_ESUCCESS)
return err;

err = uvwasi__resolve_path(uvwasi,
old_wrap,
old_path,
Expand Down Expand Up @@ -1922,12 +1926,11 @@ uvwasi_errno_t uvwasi_path_open(uvwasi_t* uvwasi,
}

r = uv_fs_open(NULL, &req, resolved_path, flags, 0666, NULL);
uv_mutex_unlock(&dirfd_wrap->mutex);
uv_fs_req_cleanup(&req);

if (r < 0) {
uv_mutex_unlock(&dirfd_wrap->mutex);
if (r < 0)
return uvwasi__translate_uv_error(r);
}

/* Not all platforms support UV_FS_O_DIRECTORY, so get the file type and check
it here. */
Expand Down Expand Up @@ -1960,11 +1963,9 @@ uvwasi_errno_t uvwasi_path_open(uvwasi_t* uvwasi,

*fd = wrap->id;
uv_mutex_unlock(&wrap->mutex);
uv_mutex_unlock(&dirfd_wrap->mutex);
return UVWASI_ESUCCESS;

close_file_and_error_exit:
uv_mutex_unlock(&dirfd_wrap->mutex);
uv_fs_close(NULL, &req, r, NULL);
uv_fs_req_cleanup(&req);
return err;
Expand Down Expand Up @@ -2079,36 +2080,41 @@ uvwasi_errno_t uvwasi_path_rename(uvwasi_t* uvwasi,
if (uvwasi == NULL || old_path == NULL || new_path == NULL)
return UVWASI_EINVAL;

uvwasi_fd_table_lock(&uvwasi->fds);

if (old_fd == new_fd) {
err = uvwasi_fd_table_get(&uvwasi->fds,
old_fd,
&old_wrap,
UVWASI_RIGHT_PATH_RENAME_SOURCE |
UVWASI_RIGHT_PATH_RENAME_TARGET,
0);
if (err != UVWASI_ESUCCESS)
return err;
err = uvwasi_fd_table_get_nolock(&uvwasi->fds,
old_fd,
&old_wrap,
UVWASI_RIGHT_PATH_RENAME_SOURCE |
UVWASI_RIGHT_PATH_RENAME_TARGET,
0);
new_wrap = old_wrap;
} else {
err = uvwasi_fd_table_get(&uvwasi->fds,
old_fd,
&old_wrap,
UVWASI_RIGHT_PATH_RENAME_SOURCE,
0);
if (err != UVWASI_ESUCCESS)
return err;

err = uvwasi_fd_table_get(&uvwasi->fds,
new_fd,
&new_wrap,
UVWASI_RIGHT_PATH_RENAME_TARGET,
0);
err = uvwasi_fd_table_get_nolock(&uvwasi->fds,
old_fd,
&old_wrap,
UVWASI_RIGHT_PATH_RENAME_SOURCE,
0);
if (err != UVWASI_ESUCCESS) {
uv_mutex_unlock(&old_wrap->mutex);
uvwasi_fd_table_unlock(&uvwasi->fds);
return err;
}

err = uvwasi_fd_table_get_nolock(&uvwasi->fds,
new_fd,
&new_wrap,
UVWASI_RIGHT_PATH_RENAME_TARGET,
0);
if (err != UVWASI_ESUCCESS)
uv_mutex_unlock(&old_wrap->mutex);
}

uvwasi_fd_table_unlock(&uvwasi->fds);

if (err != UVWASI_ESUCCESS)
return err;

err = uvwasi__resolve_path(uvwasi,
old_wrap,
old_path,
Expand Down