Message ID | 1440714454-29878-1-git-send-email-laurent@vivier.eu |
---|---|
State | New |
Headers | show |
On 27 August 2015 at 23:27, Laurent Vivier <laurent@vivier.eu> wrote: > This patch allows to run example given by open_by_handle_at(2): > > The following shell session demonstrates the use of these two programs: > > $ echo 'Can you please think about it?' > cecilia.txt > $ ./t_name_to_handle_at cecilia.txt > fh > $ ./t_open_by_handle_at < fh > open_by_handle_at: Operation not permitted > $ sudo ./t_open_by_handle_at < fh # Need CAP_SYS_ADMIN > Read 31 bytes > $ rm cecilia.txt > > Now we delete and (quickly) re-create the file so that it has the same > content and (by chance) the same inode.[...] > > $ stat --printf="%i\n" cecilia.txt # Display inode number > 4072121 > $ rm cecilia.txt > $ echo 'Can you please think about it?' > cecilia.txt > $ stat --printf="%i\n" cecilia.txt # Check inode number > 4072121 > $ sudo ./t_open_by_handle_at < fh > open_by_handle_at: Stale NFS file handle > > See the man page for source code. > > Signed-off-by: Laurent Vivier <laurent@vivier.eu> > --- > linux-user/syscall.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 97 insertions(+) > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index f62c698..725ed66 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -5246,6 +5246,93 @@ static int do_futex(target_ulong uaddr, int op, int val, target_ulong timeout, > return -TARGET_ENOSYS; > } > } > +#if defined(TARGET_NR_name_to_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) > +static abi_long do_name_to_handle_at(abi_long arg1, abi_long arg2, > + abi_long arg3, abi_long arg4, > + abi_long arg5) Since this is in its own function you have the opportunity to give the input parameters more meaningful names than arg1..arg5. > +{ > + struct file_handle *target_fh; > + struct file_handle *fh; > + int mount_id = 0; > + abi_long ret; > + char *name; > + unsigned int size; > + > + if (get_user_s32(size, arg3)) { > + return -TARGET_EFAULT; > + } > + > + name = lock_user_string(arg2); > + if (!name) { > + return -TARGET_EFAULT; > + } > + > + target_fh = lock_user(VERIFY_WRITE, arg3, > + sizeof(struct file_handle) + size, 0); > + if (!target_fh) { > + unlock_user(name, arg2, 0); > + return -TARGET_EFAULT; > + } > + > + fh = g_malloc0(sizeof(struct file_handle) + size); > + fh->handle_bytes = size; I was going to suggest just using target_fh, since we know the host and guest have the same sized struct here. But I guess they might have different alignment restrictions. > + > + ret = get_errno(name_to_handle_at(arg1, path(name), fh, &mount_id, arg5)); > + unlock_user(name, arg2, 0); > + > + /* man name_to_handle_at(2): > + * Other than the use of the handle_bytes field, the caller should treat > + * the file_handle structure as an opaque data type > + */ > + > + memcpy(target_fh, fh, fh->handle_bytes); > + target_fh->handle_bytes = tswap32(fh->handle_bytes); You need to swap the handle_type field too (to match the swap you do in do_open_by_handle_at()). (I think swapping in both places is better than doing so in neither.) Otherwise looks good. thanks -- PMM
diff --git a/linux-user/syscall.c b/linux-user/syscall.c index f62c698..725ed66 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -5246,6 +5246,93 @@ static int do_futex(target_ulong uaddr, int op, int val, target_ulong timeout, return -TARGET_ENOSYS; } } +#if defined(TARGET_NR_name_to_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) +static abi_long do_name_to_handle_at(abi_long arg1, abi_long arg2, + abi_long arg3, abi_long arg4, + abi_long arg5) +{ + struct file_handle *target_fh; + struct file_handle *fh; + int mount_id = 0; + abi_long ret; + char *name; + unsigned int size; + + if (get_user_s32(size, arg3)) { + return -TARGET_EFAULT; + } + + name = lock_user_string(arg2); + if (!name) { + return -TARGET_EFAULT; + } + + target_fh = lock_user(VERIFY_WRITE, arg3, + sizeof(struct file_handle) + size, 0); + if (!target_fh) { + unlock_user(name, arg2, 0); + return -TARGET_EFAULT; + } + + fh = g_malloc0(sizeof(struct file_handle) + size); + fh->handle_bytes = size; + + ret = get_errno(name_to_handle_at(arg1, path(name), fh, &mount_id, arg5)); + unlock_user(name, arg2, 0); + + /* man name_to_handle_at(2): + * Other than the use of the handle_bytes field, the caller should treat + * the file_handle structure as an opaque data type + */ + + memcpy(target_fh, fh, fh->handle_bytes); + target_fh->handle_bytes = tswap32(fh->handle_bytes); + g_free(fh); + unlock_user(target_fh, arg3, size); + + if (put_user_s32(mount_id, arg4)) { + return -TARGET_EFAULT; + } + + return ret; + +} +#endif + +#if defined(TARGET_NR_open_by_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) +static abi_long do_open_by_handle_at(abi_long arg1, abi_long arg2, + abi_long arg3) +{ + struct file_handle *target_fh; + struct file_handle *fh; + unsigned int size; + abi_long ret; + + if (get_user_s32(size, arg2)) { + return -TARGET_EFAULT; + } + + target_fh = lock_user(VERIFY_READ, arg2, + sizeof(struct file_handle) + size, 1); + if (!target_fh) { + return -TARGET_EFAULT; + } + + fh = g_malloc0(sizeof(struct file_handle) + size); + memcpy(fh, target_fh, size); + fh->handle_bytes = size; + fh->handle_type = tswap32(target_fh->handle_type); + + ret = get_errno(open_by_handle_at(arg1, fh, + target_to_host_bitmask(arg3, fcntl_flags_tbl))); + + g_free(fh); + + unlock_user(target_fh, arg2, sizeof(struct file_handle) + size); + + return ret; +} +#endif /* Map host to target signal numbers for the wait family of syscalls. Assume all other status bits are the same. */ @@ -5655,6 +5742,16 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, arg4)); unlock_user(p, arg2, 0); break; +#if defined(TARGET_NR_name_to_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) + case TARGET_NR_name_to_handle_at: + ret = do_name_to_handle_at(arg1, arg2, arg3, arg4, arg5); + break; +#endif +#if defined(TARGET_NR_open_by_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) + case TARGET_NR_open_by_handle_at: + ret = do_open_by_handle_at(arg1, arg2, arg3); + break; +#endif case TARGET_NR_close: ret = get_errno(close(arg1)); break;
This patch allows to run example given by open_by_handle_at(2): The following shell session demonstrates the use of these two programs: $ echo 'Can you please think about it?' > cecilia.txt $ ./t_name_to_handle_at cecilia.txt > fh $ ./t_open_by_handle_at < fh open_by_handle_at: Operation not permitted $ sudo ./t_open_by_handle_at < fh # Need CAP_SYS_ADMIN Read 31 bytes $ rm cecilia.txt Now we delete and (quickly) re-create the file so that it has the same content and (by chance) the same inode.[...] $ stat --printf="%i\n" cecilia.txt # Display inode number 4072121 $ rm cecilia.txt $ echo 'Can you please think about it?' > cecilia.txt $ stat --printf="%i\n" cecilia.txt # Check inode number 4072121 $ sudo ./t_open_by_handle_at < fh open_by_handle_at: Stale NFS file handle See the man page for source code. Signed-off-by: Laurent Vivier <laurent@vivier.eu> --- linux-user/syscall.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+)