diff options
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 116 |
1 files changed, 45 insertions, 71 deletions
diff --git a/fs/namei.c b/fs/namei.c index 86512b4d38f..e70ebab9624 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -116,47 +116,37 @@ * POSIX.1 2.4: an empty pathname is invalid (ENOENT). * PATH_MAX includes the nul terminator --RR. */ -static int do_getname(const char __user *filename, char *page) -{ - int retval; - unsigned long len = PATH_MAX; - - if (!segment_eq(get_fs(), KERNEL_DS)) { - if ((unsigned long) filename >= TASK_SIZE) - return -EFAULT; - if (TASK_SIZE - (unsigned long) filename < PATH_MAX) - len = TASK_SIZE - (unsigned long) filename; - } - - retval = strncpy_from_user(page, filename, len); - if (retval > 0) { - if (retval < len) - return 0; - return -ENAMETOOLONG; - } else if (!retval) - retval = -ENOENT; - return retval; -} - static char *getname_flags(const char __user *filename, int flags, int *empty) { - char *result = __getname(); - int retval; + char *result = __getname(), *err; + int len; - if (!result) + if (unlikely(!result)) return ERR_PTR(-ENOMEM); - retval = do_getname(filename, result); - if (retval < 0) { - if (retval == -ENOENT && empty) + len = strncpy_from_user(result, filename, PATH_MAX); + err = ERR_PTR(len); + if (unlikely(len < 0)) + goto error; + + /* The empty path is special. */ + if (unlikely(!len)) { + if (empty) *empty = 1; - if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { - __putname(result); - return ERR_PTR(retval); - } + err = ERR_PTR(-ENOENT); + if (!(flags & LOOKUP_EMPTY)) + goto error; + } + + err = ERR_PTR(-ENAMETOOLONG); + if (likely(len < PATH_MAX)) { + audit_getname(result); + return result; } - audit_getname(result); - return result; + +error: + __putname(result); + return err; } char *getname(const char __user * filename) @@ -1150,12 +1140,25 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, */ if (nd->flags & LOOKUP_RCU) { unsigned seq; - *inode = nd->inode; - dentry = __d_lookup_rcu(parent, name, &seq, inode); + dentry = __d_lookup_rcu(parent, name, &seq, nd->inode); if (!dentry) goto unlazy; - /* Memory barrier in read_seqcount_begin of child is enough */ + /* + * This sequence count validates that the inode matches + * the dentry name information from lookup. + */ + *inode = dentry->d_inode; + if (read_seqcount_retry(&dentry->d_seq, seq)) + return -ECHILD; + + /* + * This sequence count validates that the parent had no + * changes while we did the lookup of the dentry above. + * + * The memory barrier in read_seqcount_begin of child is + * enough, we can use __read_seqcount_retry here. + */ if (__read_seqcount_retry(&parent->d_seq, nd->seq)) return -ECHILD; nd->seq = seq; @@ -1403,18 +1406,9 @@ static inline int can_lookup(struct inode *inode) */ #ifdef CONFIG_DCACHE_WORD_ACCESS -#ifdef CONFIG_64BIT +#include <asm/word-at-a-time.h> -/* - * Jan Achrenius on G+: microoptimized version of - * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56" - * that works for the bytemasks without having to - * mask them first. - */ -static inline long count_masked_bytes(unsigned long mask) -{ - return mask*0x0001020304050608ul >> 56; -} +#ifdef CONFIG_64BIT static inline unsigned int fold_hash(unsigned long hash) { @@ -1424,15 +1418,6 @@ static inline unsigned int fold_hash(unsigned long hash) #else /* 32-bit case */ -/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */ -static inline long count_masked_bytes(long mask) -{ - /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */ - long a = (0x0ff0001+mask) >> 23; - /* Fix the 1 for 00 case */ - return a & mask; -} - #define fold_hash(x) (x) #endif @@ -1443,7 +1428,7 @@ unsigned int full_name_hash(const unsigned char *name, unsigned int len) unsigned long hash = 0; for (;;) { - a = *(unsigned long *)name; + a = load_unaligned_zeropad(name); if (len < sizeof(unsigned long)) break; hash += a; @@ -1460,17 +1445,6 @@ done: } EXPORT_SYMBOL(full_name_hash); -#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x)) -#define ONEBYTES REPEAT_BYTE(0x01) -#define SLASHBYTES REPEAT_BYTE('/') -#define HIGHBITS REPEAT_BYTE(0x80) - -/* Return the high bit set in the first byte that is a zero */ -static inline unsigned long has_zero(unsigned long a) -{ - return ((a - ONEBYTES) & ~a) & HIGHBITS; -} - /* * Calculate the length and hash of the path component, and * return the length of the component; @@ -1484,9 +1458,9 @@ static inline unsigned long hash_name(const char *name, unsigned int *hashp) do { hash = (hash + a) * 9; len += sizeof(unsigned long); - a = *(unsigned long *)(name+len); + a = load_unaligned_zeropad(name+len); /* Do we have any NUL or '/' bytes in this word? */ - mask = has_zero(a) | has_zero(a ^ SLASHBYTES); + mask = has_zero(a) | has_zero(a ^ REPEAT_BYTE('/')); } while (!mask); /* The mask *below* the first high bit set */ |