On Sun, May 21, 2017 at 04:03:55PM +0200, Jilles Tjoelker wrote: > On Sun, May 21, 2017 at 03:31:18PM +0300, Konstantin Belousov wrote: > > On Sun, May 21, 2017 at 02:14:56PM +0200, Jilles Tjoelker wrote: > > > We have another type in this area which is too small in some situations: > > > uint8_t for struct dirent.d_namlen. For filesystems that store filenames > > > as upto 255 UTF-16 code units, the name to be stored in d_name may be > > > upto 765 bytes long in UTF-8. This was reported in PR 204643. The code > > > currently handles this by returning the short (8.3) name, but this name > > > may not be present or usable, leaving the file inaccessible. > > > > Actually allowing longer names seems too complicated to add to the ino64 > > > change, but changing d_namlen to uint16_t (using d_pad0 space) and > > > skipping entries with d_namlen > 255 in libc may be helpful. > > > > Note that applications using the deprecated readdir_r() will not be able > > > to read such long names, since the API does not allow specifying that a > > > larger buffer has been provided. (This could be avoided by making struct > > > dirent.d_name 766 bytes long instead of 256.) > > > > Unfortunately, the existence of readdir_r() also prevents changing > > > struct dirent.d_name to the more correct flexible array. > > > Yes, changing the size of d_name at this stage of the project is out of > > question. My reading of your proposal is that we should extend the size > > of d_namlen to uint16_t, am I right ? Should we go to 32bit directly > > then, perhaps ? > > Yes, my proposal is to change d_namlen to uint16_t. > > Making it 32 bits is not useful with the 16-bit d_reclen, and increasing > d_reclen does not seem useful to me with the current model of > getdirentries() where the whole dirent must fit into the caller's > buffer. Bumping it now might cause less churn later, even if unused, but ok. > > > I did not committed the change below, nor did I tested or even build it. > > I'd like to skip overlong names in the native readdir_r() as well, so > that long name support can be added to the kernel later without causing > buffer overflows with applications using FreeBSD 12.0 libc. > > The native readdir() does not seem to have such a problem. Again, not even compiled. diff --git a/lib/libc/gen/readdir-compat11.c b/lib/libc/gen/readdir-compat11.c index 1c52f563c75..a865ab9157e 100644 --- a/lib/libc/gen/readdir-compat11.c +++ b/lib/libc/gen/readdir-compat11.c _at__at_ -41,6 +41,7 _at__at_ __FBSDID("$FreeBSD$"); #define _WANT_FREEBSD11_DIRENT #include <dirent.h> #include <errno.h> +#include <stdbool.h> #include <stddef.h> #include <stdlib.h> #include <string.h> _at__at_ -53,10 +54,12 _at__at_ __FBSDID("$FreeBSD$"); #include "gen-compat.h" -static void +static bool freebsd11_cvtdirent(struct freebsd11_dirent *dstdp, struct dirent *srcdp) { + if (srcdp->d_namelen >= sizeof(dstdp->d_name)) + return (false); dstdp->d_type = srcdp->d_type; dstdp->d_namlen = srcdp->d_namlen; dstdp->d_fileno = srcdp->d_fileno; /* truncate */ _at__at_ -65,6 +68,7 _at__at_ freebsd11_cvtdirent(struct freebsd11_dirent *dstdp, struct dirent *srcdp) bzero(dstdp->d_name + dstdp->d_namlen, dstdp->d_reclen - offsetof(struct freebsd11_dirent, d_name) - dstdp->d_namlen); + return (true); } struct freebsd11_dirent * _at__at_ -75,13 +79,15 _at__at_ freebsd11_readdir(DIR *dirp) if (__isthreaded) _pthread_mutex_lock(&dirp->dd_lock); - dp = _readdir_unlocked(dirp, 1); + dp = _readdir_unlocked(dirp, RDU_SKIP); if (dp != NULL) { if (dirp->dd_compat_de == NULL) dirp->dd_compat_de = malloc(sizeof(struct freebsd11_dirent)); - freebsd11_cvtdirent(dirp->dd_compat_de, dp); - dstdp = dirp->dd_compat_de; + if (freebsd11_cvtdirent(dirp->dd_compat_de, dp)) + dstdp = dirp->dd_compat_de; + else + dstdp = NULL; } else dstdp = NULL; if (__isthreaded) _at__at_ -101,8 +107,10 _at__at_ freebsd11_readdir_r(DIR *dirp, struct freebsd11_dirent *entry, if (error != 0) return (error); if (xresult != NULL) { - freebsd11_cvtdirent(entry, &xentry); - *result = entry; + if (freebsd11_cvtdirent(entry, &xentry)) + *result = entry; + else /* should not happen due to RDU_SHORT */ + *result = NULL; } else *result = NULL; return (0); diff --git a/lib/libc/gen/readdir.c b/lib/libc/gen/readdir.c index dc7b0df18b2..c30d48273b8 100644 --- a/lib/libc/gen/readdir.c +++ b/lib/libc/gen/readdir.c _at__at_ -49,7 +49,7 _at__at_ __FBSDID("$FreeBSD$"); * get next entry in a directory. */ struct dirent * -_readdir_unlocked(DIR *dirp, int skip) +_readdir_unlocked(DIR *dirp, int flags) { struct dirent *dp; long initial_seek; _at__at_ -80,10 +80,13 _at__at_ _readdir_unlocked(DIR *dirp, int skip) dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc) return (NULL); dirp->dd_loc += dp->d_reclen; - if (dp->d_ino == 0 && skip) + if (dp->d_ino == 0 && (flags & RDU_SKIP) != 0) continue; if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW)) continue; + if (dp->d_namlen >= sizeof(d_namlen) && + (flags & RDU_SHORT) != 0) + continue; return (dp); } } _at__at_ -91,15 +94,13 _at__at_ _readdir_unlocked(DIR *dirp, int skip) struct dirent * readdir(DIR *dirp) { - struct dirent *dp; + struct dirent *dp; - if (__isthreaded) { + if (__isthreaded) _pthread_mutex_lock(&dirp->dd_lock); - dp = _readdir_unlocked(dirp, 1); + dp = _readdir_unlocked(dirp, RDU_SKIP); + if (__isthreaded) _pthread_mutex_unlock(&dirp->dd_lock); - } - else - dp = _readdir_unlocked(dirp, 1); return (dp); } _at__at_ -111,14 +112,13 _at__at_ __readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result) saved_errno = errno; errno = 0; - if (__isthreaded) { + if (__isthreaded) _pthread_mutex_lock(&dirp->dd_lock); - if ((dp = _readdir_unlocked(dirp, 1)) != NULL) - memcpy(entry, dp, _GENERIC_DIRSIZ(dp)); - _pthread_mutex_unlock(&dirp->dd_lock); - } - else if ((dp = _readdir_unlocked(dirp, 1)) != NULL) + dp = _readdir_unlocked(dirp, RDU_SKIP | RDU_SHORT); + if (dp != NULL) memcpy(entry, dp, _GENERIC_DIRSIZ(dp)); + if (__isthreaded) + _pthread_mutex_unlock(&dirp->dd_lock); if (errno != 0) { if (dp == NULL) diff --git a/lib/libc/gen/telldir.h b/lib/libc/gen/telldir.h index 96ff669a312..50adb351e91 100644 --- a/lib/libc/gen/telldir.h +++ b/lib/libc/gen/telldir.h _at__at_ -66,4 +66,7 _at__at_ void _reclaim_telldir(DIR *); void _seekdir(DIR *, long); void _fixtelldir(DIR *dirp, long oldseek, long oldloc); +#define RDU_SKIP 0x0001 +#define RDU_SHORT 0x0002 + #endif diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c index 784af836aee..27b2635030d 100644 --- a/sys/kern/vfs_syscalls.c +++ b/sys/kern/vfs_syscalls.c _at__at_ -3733,7 +3733,8 _at__at_ freebsd11_kern_getdirentries(struct thread *td, int fd, char *ubuf, u_int count, if (dp->d_reclen == 0) break; MPASS(dp->d_reclen >= _GENERIC_DIRLEN(0)); - /* dp->d_namlen <= sizeof(dstdp.d_name) - 1 always */ + if (dp->d_namlen >= sizeof(dstdp.d_name)) + continue; dstdp.d_type = dp->d_type; dstdp.d_namlen = dp->d_namlen; dstdp.d_fileno = dp->d_fileno; /* truncate */ diff --git a/sys/sys/dirent.h b/sys/sys/dirent.h index 341855d0530..472142f960b 100644 --- a/sys/sys/dirent.h +++ b/sys/sys/dirent.h _at__at_ -58,8 +58,7 _at__at_ typedef __off_t off_t; * * Explicit padding between the last member of the header (d_namelen) and * d_name avoids ABI padding at the end of dirent on LP64 architectures. - * There is code depending on d_name being last. Also, retaining this - * padding on ILP32 architectures simplifies the compat32 layer. + * There is code depending on d_name being last. */ struct dirent { _at__at_ -67,8 +66,9 _at__at_ struct dirent { off_t d_off; /* directory offset of entry */ __uint16_t d_reclen; /* length of this record */ __uint8_t d_type; /* file type, see below */ - __uint8_t d_namlen; /* length of string in d_name */ - __uint32_t d_pad0; + __uint8_t d_pad0; + __uint16_t d_namlen; /* length of string in d_name */ + __uint16_t d_pad1; #if __BSD_VISIBLE #define MAXNAMLEN 255 char d_name[MAXNAMLEN + 1]; /* name must be no longer than this */Received on Sun May 21 2017 - 12:25:42 UTC
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