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proc: calculate and initialize size of /proc/<PID>/auxv

PATCH In review Takayuki Nagata 2 participants 2 messages Aug 17, 2011

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Takayuki Nagata

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#0 lore raw

PATCH 1/1 proc: calculate and initialize size of /proc/<PID>/auxv

An ls and a wc commands show 0 size for some of /proc/<PID>/* files, because getattr methods and inode->i_size variables are not implemented for these files. These files are known pseudo, but some peoples may need size of the files.

To calculate and return the size of each /proc/<PID>/auxv, proc_pid_auxv_getattr() is added. It is used when getattr() system call for the /proc/<PID>/auxv is called.

To initialize inode->i_size of each /proc/<PID>/* file, isize_initializer member of pid_entry and some macros are added, and proc_pid_auxv_isize() is added for i_size of each /proc/<PID>/auxv.

BugLink https://bugzilla.redhat.com/show_bug.cgi?id=155943
Signed-off-by Takayuki Nagata <[email protected]>
---
 fs/proc/base.c |   66 +++++++++++++++++++++++++++++++++++++++++++------------
 1 files changed, 51 insertions(+), 15 deletions(-)
fs/proc/base.c +51 -15
index fc5bc27..e45afd3 100644
@@ -105,33 +105,37 @@ struct pid_entry {
 	const struct inode_operations *iop;
 	const struct file_operations *fop;
 	union proc_op op;
+	loff_t (*isize_initializer)(struct task_struct*);
 };
 
-#define NOD(NAME, MODE, IOP, FOP, OP) {			\
+#define NOD(NAME, MODE, IOP, FOP, OP, ISIZE) {		\
 	.name = (NAME),					\
 	.len  = sizeof(NAME) - 1,			\
 	.mode = MODE,					\
 	.iop  = IOP,					\
 	.fop  = FOP,					\
 	.op   = OP,					\
+	.isize_initializer = ISIZE,			\
 }
 
 #define DIR(NAME, MODE, iops, fops)	\
-	NOD(NAME, (S_IFDIR|(MODE)), &iops, &fops, {} )
+	NOD(NAME, (S_IFDIR|(MODE)), &iops, &fops, {}, NULL )
 #define LNK(NAME, get_link)					\
 	NOD(NAME, (S_IFLNK|S_IRWXUGO),				\
 		&proc_pid_link_inode_operations, NULL,		\
-		{ .proc_get_link = get_link } )
+		{ .proc_get_link = get_link }, NULL )
 #define REG(NAME, MODE, fops)				\
-	NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})
+	NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {}, NULL )
+#define INF_WITH_IOP(NAME, MODE, read, iop, isize)	\
+	NOD(NAME, (S_IFREG|(MODE)),			\
+		iop, &proc_info_file_operations,	\
+		{ .proc_read = read }, isize )
 #define INF(NAME, MODE, read)				\
-	NOD(NAME, (S_IFREG|(MODE)), 			\
-		NULL, &proc_info_file_operations,	\
-		{ .proc_read = read } )
+	INF_WITH_IOP(NAME, MODE, read, NULL, NULL )
 #define ONE(NAME, MODE, show)				\
 	NOD(NAME, (S_IFREG|(MODE)), 			\
 		NULL, &proc_single_file_operations,	\
-		{ .proc_show = show } )
+		{ .proc_show = show }, NULL )
 
 /*
  * Count the number of hardlinks for the pid_entry table, excluding the .

@@ -309,9 +313,8 @@ out:
 	return res;
 }
 
-static int proc_pid_auxv(struct task_struct *task, char *buffer)
+inline static int count_mm_saved_auxv(struct mm_struct *mm)
 {
-	struct mm_struct *mm = mm_for_maps(task);
 	int res = PTR_ERR(mm);
 	if (mm && !IS_ERR(mm)) {
 		unsigned int nwords = 0;

@@ -321,12 +324,43 @@ static int proc_pid_auxv(struct task_struct *task, char *buffer)
 		res = nwords * sizeof(mm->saved_auxv[0]);
 		if (res > PAGE_SIZE)
 			res = PAGE_SIZE;
-		memcpy(buffer, mm->saved_auxv, res);
-		mmput(mm);
 	}
 	return res;
 }
 
+static int proc_pid_auxv(struct task_struct *task, char *buffer)
+{
+	int size;
+	struct mm_struct *mm = get_task_mm(task);
+	size = count_mm_saved_auxv(mm);
+	if (mm) {
+		if(buffer)
+			memcpy(buffer, mm->saved_auxv, size);
+		mmput(mm);
+	}
+	return size;
+}
+
+static loff_t proc_pid_auxv_isize(struct task_struct *task)
+{
+	struct mm_struct *mm = get_task_mm(task);
+	return count_mm_saved_auxv(mm);
+}
+
+static int proc_pid_auxv_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
+{
+	struct inode *inode = dentry->d_inode;
+	struct task_struct *task = get_proc_task(inode);
+	struct mm_struct *mm = get_task_mm(task);
+
+	generic_fillattr(inode, stat);
+	stat->size = count_mm_saved_auxv(mm);
+	return 0;
+}
+
+static struct inode_operations proc_pid_auxv_inode_operations = {
+	.getattr	= proc_pid_auxv_getattr,
+};
 
 #ifdef CONFIG_KALLSYMS
 /*

@@ -2253,6 +2287,8 @@ static struct dentry *proc_pident_instantiate(struct inode *dir,
 
 	ei = PROC_I(inode);
 	inode->i_mode = p->mode;
+	if (p->isize_initializer)
+		inode->i_size = p->isize_initializer(task);
 	if (S_ISDIR(inode->i_mode))
 		inode->i_nlink = 2;	/* Use getattr to fix if necessary */
 	if (p->iop)

@@ -2617,7 +2653,7 @@ static const struct inode_operations proc_self_inode_operations = {
  */
 static const struct pid_entry proc_base_stuff[] = {
 	NOD("self", S_IFLNK|S_IRWXUGO,
-		&proc_self_inode_operations, NULL, {}),
+		&proc_self_inode_operations, NULL, {}, NULL),
 };
 
 static struct dentry *proc_base_instantiate(struct inode *dir,

@@ -2774,7 +2810,7 @@ static const struct pid_entry tgid_base_stuff[] = {
 	DIR("net",        S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
 #endif
 	REG("environ",    S_IRUSR, proc_environ_operations),
-	INF("auxv",       S_IRUSR, proc_pid_auxv),
+	INF_WITH_IOP("auxv",       S_IRUSR, proc_pid_auxv, &proc_pid_auxv_inode_operations, proc_pid_auxv_isize),
 	ONE("status",     S_IRUGO, proc_pid_status),
 	ONE("personality", S_IRUGO, proc_pid_personality),
 	INF("limits",	  S_IRUGO, proc_pid_limits),

@@ -3123,7 +3159,7 @@ static const struct pid_entry tid_base_stuff[] = {
 	DIR("fdinfo",    S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
 	DIR("ns",	 S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
 	REG("environ",   S_IRUSR, proc_environ_operations),
-	INF("auxv",      S_IRUSR, proc_pid_auxv),
+	INF_WITH_IOP("auxv",      S_IRUSR, proc_pid_auxv, &proc_pid_auxv_inode_operations, proc_pid_auxv_isize),
 	ONE("status",    S_IRUGO, proc_pid_status),
 	ONE("personality", S_IRUGO, proc_pid_personality),
 	INF("limits",	 S_IRUGO, proc_pid_limits),
Signature · 1 line
1.7.4.4
maintainer
#1 lore raw
Quoted 4 lines · Takayuki Nagata

An ls and a wc commands show 0 size for some of /proc/<PID>/* files, because getattr methods and inode->i_size variables are not implemented for these files. These files are known pseudo, but some peoples may need size of the files.

"Some people may need" is far to vague...

Quoted 1 line
BugLink https://bugzilla.redhat.com/show_bug.cgi?id=155943

Containing unanswered question by mingo, again along the lines of "WTF is that needed at all?"...

fs/proc/base.c static int proc_pid_auxv(struct task_struct *task, char *buffer) · line 340

Quoted 10 lines
fs/proc/base.c +10 -0
+static int proc_pid_auxv(struct task_struct *task, char *buffer)
+{
+	int size;
+	struct mm_struct *mm = get_task_mm(task);
+	size = count_mm_saved_auxv(mm);
+	if (mm) {
+		if(buffer)
+			memcpy(buffer, mm->saved_auxv, size);
+		mmput(mm);
+	}

Oh, lovely - so we are allowing anybody to read it, suid exec be damned.

fs/proc/base.c static int proc_pid_auxv(struct task_struct *task, char *buffer) · line 347

Quoted 4 lines
fs/proc/base.c +4 -0
+static loff_t proc_pid_auxv_isize(struct task_struct *task)
+{
+	struct mm_struct *mm = get_task_mm(task);
+	return count_mm_saved_auxv(mm);

... and that simply leaks.

fs/proc/base.c static int proc_pid_auxv(struct task_struct *task, char *buffer) · line 357

Quoted 8 lines
fs/proc/base.c +8 -0
+static int proc_pid_auxv_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
+{
+	struct inode *inode = dentry->d_inode;
+	struct task_struct *task = get_proc_task(inode);
+	struct mm_struct *mm = get_task_mm(task);
+
+	generic_fillattr(inode, stat);
+	stat->size = count_mm_saved_auxv(mm);

... and so does this, both mm and task.

Ancient bz entry with unanswered objections in it, broken patch, no rationale in sight... NAK with extreme prejudice.